Artykuły w czasopismach na temat „Forest fragments”
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Shen, Chunyu, Nannan Shi, Shenglei Fu, Wanhui Ye, Lei Ma i Dongsheng Guan. "Decline in Aboveground Biomass Due to Fragmentation in Subtropical Forests of China". Forests 12, nr 5 (13.05.2021): 617. http://dx.doi.org/10.3390/f12050617.
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Fragmentation has long been considered the primary cause for ecosystem degradation and biodiversity loss worldwide. Forest fragmentation affects ecosystem functioning and biodiversity in multiple ways. Here, we ask how forest fragmentation influences aboveground biomass storage (AGB) in sub-tropical forests in China. We established 207 20 m × 20 m plots within 69 forest fragments of varying size. Forest fragmentation process simulation was carried out via repeated quadrat sampling using different sized quadrats in two non-fragmented stands. AGB was estimated and compared across forest fragments and quadrats with different sizes within two non-fragmented stands. Our results indicate that AGB is significantly lower in forest fragments than in quadrats within two non-fragmented forests. In addition, species richness and abundance were lower in fragmented stands, respectively. In fragmented forests, the average diameter at breast height (DBH) increased with decreasing patch size, while declined for non-fragmented plots. Species richness, abundance, and mean DBH have strongly positive effects on AGB. This was the case both in forest fragments and quadrats within two non-fragmented forests. Forest fragmentation leads to lower richness, lower abundance, and higher mean DBH in forest fragments than in the two non-fragmented forests. Our results suggest that forest fragmentation increases edge habitats, which drastically decreases forests aboveground biomass storage. These results show that land degradation not only reduces the area of forests, but also reduces the aboveground biomass carbon density of forests.
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MARINI, MIGUEL Â. "Effects of forest fragmentation on birds of the cerrado region, Brazil". Bird Conservation International 11, nr 1 (marzec 2001): 13–25. http://dx.doi.org/10.1017/s0959270901001034.
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Bird surveys were conducted through observations and mist-netting in six forest fragments in the cerrado region of central Brazil, to evaluate the effects of fragmentation on bird species richness and community composition. Smaller forest fragments had fewer species than larger fragments. The proportion of species in most foraging guilds did not change with forest size, except for that of granivores, which decreased as fragment size increased. The proportion of forest-dependent species increased significantly with increasing fragment size while that of semi-dependent species significantly decreased. Forest-dependent endemic birds, however, were not area sensitive, but appeared to be partially dependent on the flooded forests of the region. Conservation policies for the region should conserve both large and small forest fragments urgently, and flooded forests especially.
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Rodríguez-Mendoza, Clara, i Eduardo Pineda. "Importance of riparian remnants for frog species diversity in a highly fragmented rainforest". Biology Letters 6, nr 6 (16.06.2010): 781–84. http://dx.doi.org/10.1098/rsbl.2010.0334.
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Tropical forests undergo continuous transformation to other land uses, resulting in landscapes typified by forest fragments surrounded by anthropogenic habitats. Small forest fragments, specifically strip-shaped remnants flanking streams (referred to as riparian remnants), can be particularly important for the maintenance and conservation of biodiversity within highly fragmented forests. We compared frog species diversity between riparian remnants, other forest fragments and cattle pastures in a tropical landscape in Los Tuxtlas, Mexico. We found similar species richness in the three habitats studied and a similar assemblage structure between riparian remnants and forest fragments, although species composition differed by 50 per cent. Frog abundance was halved in riparian remnants compared with forest fragments, but was twice that found in pastures. Our results suggest that riparian remnants play an important role in maintaining a portion of frog species diversity in a highly fragmented forest, particularly during environmentally stressful (hot and dry) periods. In this regard, however, the role of riparian remnants is complementary, rather than substitutive, with respect to the function of other forest fragments within the fragmented forest.
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Calle-Rendón, Bayron R., Renato R. Hilário i José Julio de Toledo. "Effect of Site Attributes and Matrix Composition on Neotropical Primate Species Richness and Functional Traits: A Comparison Among Regions". Diversity 11, nr 5 (25.05.2019): 83. http://dx.doi.org/10.3390/d11050083.
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Fragmentation threatens biodiversity and forest-dwelling animals can be especially vulnerable. Neotropical primates inhabit forests and play ecological roles in maintaining forest biodiversity. Currently, many primate communities are restricted to forest fragments. We (1) evaluated the influence of environmental, matrix, and site attributes on species richness and functional traits of primates in the Neotropics; and (2) evaluated the effect of the sub-region on the relationships between primates and environmental, matrix, and site attributes. We conducted literature searches to find published data on primate communities in forest fragments throughout the Neotropics. Each fragment was assigned to 1 of 11 sub-regions: Mesoamerica, Tumbes-Chocó-Magdalena, Caribbean, Orinoco, Amazon, Atlantic Forest, Cerrado, Chaco, Andes, Caatinga, and Pampa. Based on actual and expected species occurrences, we calculated the proportion of primate species retained in the fragments, the mass retained, and dietary items retained considering reproductive and vegetative plant parts and prey. We used linear mixed models to correlate primate variables with environmental, matrix, and site attributes. Fragment area was more important for primate retention than environmental, matrix, and site attributes, with primate retention being higher in larger fragments. Fragment size was positively correlated with all primate variables, except for retention of prey consumption, whose retention decreased as water bodies and density of buildings in the matrix increased. Fragments within protected areas retained larger species than unprotected fragments. The proportion of extant mass retained and vegetative plant parts in the diet were highest in Mesoamerica and lowest in the Atlantic Forest. Conservation planning of Neotropical primates should consider both the differences among sub-regions, forest restoration to increase fragment size, and the creation of new protected areas, even in fragmented landscapes.
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Hansen, Matthew C., Lei Wang, Xiao-Peng Song, Alexandra Tyukavina, Svetlana Turubanova, Peter V. Potapov i Stephen V. Stehman. "The fate of tropical forest fragments". Science Advances 6, nr 11 (marzec 2020): eaax8574. http://dx.doi.org/10.1126/sciadv.aax8574.
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Tropical forest fragmentation results in habitat and biodiversity loss and increased carbon emissions. Here, we link an increased likelihood of tropical forest loss to decreasing fragment size, particularly in primary forests. The relationship holds for protected areas, albeit with half the rate of loss compared with all fragments. The fact that disturbance increases as primary forest fragment size decreases reflects higher land use pressures and improved access for resource extraction and/or conversion in smaller fragments. Large remaining forest fragments are found in the Amazon and Congo Basins and Insular Southeast Asia, with the majority of large extent/low loss fragments located in the Amazon. Tropical areas without large fragments, including Central America, West Africa, and mainland Southeast Asia, have higher loss within and outside of protected areas. Results illustrate the need for rigorous land use planning, management, and enforcement in maintaining large tropical forest fragments and restoring regions of advanced fragmentation.
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Bayne, Erin, i Keith Hobson. "Relative use of contiguous and fragmented boreal forest by red squirrels (Tamiasciurus hudsonicus)". Canadian Journal of Zoology 78, nr 3 (1.04.2000): 359–65. http://dx.doi.org/10.1139/z99-219.
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We examined whether forest fragmentation by agriculture influenced the abundance of North American red squirrels (Tamiasciurus hudsonicus) in the southern boreal mixedwood forest of Saskatchewan. During the summers of 1995 and 1997, we determined the relative abundance of red squirrels in 43 forest fragments ranging in size from 0.2 to 82 ha and in 15 sites in nearby contiguous forest. Relative abundance was determined using acoustic point count surveys, in which all squirrel vocalizations were recorded. Within the fragmented agricultural landscape, we found that red squirrel abundance increased slightly with forest-fragment size, whereas the abundance of red squirrels was negatively correlated with the amount of forest cover within 1 km of a site. We also compared squirrel abundance in forest fragments with that in contiguous forest and found that red squirrels were significantly more abundant in forest fragments than in contiguous forest. We speculate that changes in dispersal patterns in fragmented forest habitats, higher squirrel survival in forest fragments, and differences in diet between contiguous and fragmented forest habitats contributed to this pattern. Our results suggest that forest fragmentation may not be particularly detrimental to habitat generalists like the red squirrel. However, an increased abundance of red squirrels in forest fragments may result in negative effects on other species, such as forest songbirds.
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HARRINGTON, G. N., A. N. D. FREEMAN i F. H. J. CROME. "The effects of fragmentation of an Australian tropical rain forest on populations and assemblages of small mammals". Journal of Tropical Ecology 17, nr 2 (marzec 2001): 225–40. http://dx.doi.org/10.1017/s0266467401001158.
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Small mammals were trapped in four rain forest fragments (3, 8, 20 and 97 ha), in an agricultural landscape, and in comparable continuous tropical rain forest in north Queensland, Australia over 2 y. The most frequently captured species were four murid rodents. Melomys cervinipes were captured in similar numbers in both continuous and fragmented forest. This species achieves greatest abundance at forest edges and this study suggests that edges of fragments and edges of continuous forest will support similar densities. Abundance of Uromys caudimaculatus was positively correlated with size of fragment and peaked in continuous forest. This species had a home range larger than the smaller fragments and was thus disadvantaged but its ability to utilize the agricultural matrix between fragments mitigated the effect. Rattus leucopus and R. fuscipes were most abundant in fragments and continuous forest respectively but both species occurred in similar abundance in the 97-ha fragment. This suggests their population size is related to habitat rather than competitive exclusion as previously postulated. Ordination of the populations of the nine most commonly captured mammals, separated the fragment and continuous sites but placed the largest fragment closest to the continuous sites. The contrasting response of the two Rattus spp. was the primary influence on the ordination. Second in importance was Trichosurus vulpecula, a folivorous possum, which was absent from the continuous sites. The fragments may have had more nutrient-rich, pioneer tree foliage than continuous forest. Isoodon macrourus, Perameles nasuta, Antechinus godmani and Uromys hadrourus also showed positive or negative response to fragmentation. Species utilizing the matrix between forest fragments and species adapted to forest edge are advantaged by the fragmentation process whereas forest specialists tend to extinction in fragments, particularly where the home range of the animal is not many times smaller than the fragment.
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Wang, Zhenning, Jianping Yin, Xudong Li i Jianya Yi. "Effect of Wood Medium on Dispersion Parameters of Prefabricated Spherical Fragments in Forest". Applied Sciences 12, nr 22 (8.11.2022): 11333. http://dx.doi.org/10.3390/app122211333.
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In order to study the influence of the forest environment on the killing power of prefabricated fragments, the relationship between the wood medium in the forest and the residual velocity of prefabricated fragments and a simple calculation model were obtained. The impact test of 300 mm thick pine target plate was carried out with 6 mm and 11 mm diameter tungsten alloy spherical fragments. The LS-DYNA finite element modeling of wood was carried out and compared with the experimental parameters, which verified the reliability of the numerical simulation method on the residual velocity of fragments. Based on this, a simple mathematical calculation method for the forest environment is constructed to calculate the penetration track length of fragments in the forest environment. Combined with the model and the formula for calculating the residual velocity of wood, the impact of forests on fragments within a certain radius can be evaluated. According to the characteristics of the forest environment, the boundary effects of the multi-layer spacing targets and trees were further studied. The research shows that the wood reduces the fragment power mainly by affecting the penetration length. The influence of forest density, tree diameter, and other parameters on the fragment velocity attenuation in the forest environment is analyzed. Using this method, the influence of forest environmental parameters on fragment dispersion parameters can be simply evaluated.
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CÂNDIDO, Maria Eliene Maia Braga, Patrícia Nakayama MIRANDA i Elder Ferreira MORATO. "Orchid bees in riparian and terra-firme forest fragments in an urban matrix in southwestern Brazilian Amazonia". Acta Amazonica 51, nr 3 (wrzesień 2021): 214–23. http://dx.doi.org/10.1590/1809-4392202003781.
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ABSTRACT Riparian forests are important ecosystems that support an enormous biodiversity in Brazil. Despite being protected under Brazilian legislation, these forests suffer great impact from the fragmentation of habitats. Orchid bees are a key group of pollinators in the Neotropical region, yet few data are available on the assamblage structure of these bees in riparian forests. We evaluated the role of fragments of riparian and terra-firme forest on the conservation and maintenance of orchid bees in an urban landscape in the southwestern Amazon basin. Specifically, we evaluated whether bee assemblages in riparian and terra-firme forests differed significantly in abundance, species richness and composition. We also evaluated whether species richness and abundance of bees vary with the size of the forest fragment. Male bees were attracted using odoriferous baits and collected with entomological nets in 10 forest fragments. There was no significant difference between riparian and terra-firme fragments in species abundance, richness and composition, but there was a positive correlation between fragment size and species richness and abundance. Our results suggest that, in an urban landscape, the remaining riparian and terra-firme forest fragments still could maintain 62.7% of the orchid bee species known to occur in the region, reinforcing the conservation value of these forest remnants. Our findings indicate that these fragments provide a potentially important habitat for the maintenance of local bee populations in the landscape.
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Šipek, Mirjana, Lado Kutnar, Aleksander Marinšek i Nina Šajna. "Contrasting Responses of Alien and Ancient Forest Indicator Plant Species to Fragmentation Process in the Temperate Lowland Forests". Plants 11, nr 23 (6.12.2022): 3392. http://dx.doi.org/10.3390/plants11233392.
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Fragmentation is one of the major threats to biodiversity. In a fragmented landscape, forest specialists are losing suitable forest habitats with specific site and microclimate conditions, which results in their local extinction. Conversely, the invasion of alien species is facilitated by open forest areas and increased boundaries between forest fragments and adjacent land. We studied the effect of fragmentation in terms of fragment size impact on overall plant species richness and on selected ecologically important groups’ richness, composition, and diversity. We surveyed vegetation in the interior of 47 fragments of various sizes and one unfragmented reference forest. Our results reveal that the effect of fragmentation is complex and differs for studied plant groups. Decreasing fragment size negatively affects the overall plant richness and richness of native and ancient forest indicator plants as well as their diversity, while the effect is positive for alien plants. The highest proportion of ancient forest indicator plant species and the lowest proportion of alien plants in the unfragmented forest underline the great conservation value of forest fragments. At the same time, our results reveal that large and diverse forest ecosystems are susceptible to biological invasions as well.
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Gerber, Brian D., Sarah M. Karpanty i Johny Randrianantenaina. "The impact of forest logging and fragmentation on carnivore species composition, density and occupancy in Madagascar's rainforests". Oryx 46, nr 3 (lipiec 2012): 414–22. http://dx.doi.org/10.1017/s0030605311001116.
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AbstractForest carnivores are threatened globally by logging and forest fragmentation yet we know relatively little about how such change affects predator populations. This is especially true in Madagascar, where carnivores have not been extensively studied. To understand better the effects of logging and fragmentation on Malagasy carnivores we evaluated species composition, density of fossa Cryptoprocta ferox and Malagasy civet Fossa fossana, and carnivore occupancy in central-eastern Madagascar. We photographically-sampled carnivores in two contiguous (primary and selectively-logged) and two fragmented rainforests (fragments <2.5 and >15 km from intact forest). Species composition varied, with more native carnivores in the contiguous than fragmented rainforests. F. fossana was absent from fragmented rainforests and at a lower density in selectively-logged than in primary rainforest (mean 1.38±SE 0.22 and 3.19±SE 0.55 individuals km−2, respectively). C. ferox was detected in fragments <2.5 km from forest and had similar densities in primary and selectively-logged forests (0.12±SE 0.05 and 0.09±SE 0.04 adults km−2, respectively) but was absent in fragments >15 km from forest. We identified only two protected areas in Madagascar that may maintain >300 adult C. ferox. Occupancy of broad-striped mongoose Galidictis fasciata was positively related to fragment size whereas occupancy of ring-tailed mongoose Galidia elegans elegans was negatively associated with increasing exotic wild cat (Felis spp.) activity at a camera site. Degraded rainforest fragments are difficult environments for Malagasy carnivores to occupy; there is a need to prioritize the reconnection and maintenance of contiguous forest tracts.
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AMARAL, Iêda Leão do, William Ernest MAGNUSSON, Francisca Dionízia de Almeida MATOS, Ana Luisa K. ALBERNAZ, Yuri Oliveira FEITOSA i Jean-Louis GUILLAUMET. "Disentangling structural patterns of natural forest fragments in a savanna matrix in the eastern Brazilian Amazon". Acta Amazonica 47, nr 2 (czerwiec 2017): 111–22. http://dx.doi.org/10.1590/1809-4392201601923.
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ABSTRACT Natural fragments are an important source of richness for the management and conservation of a local flora. The objective of this study was to evaluate the effect of fragmentation on the structure and composition of the plant communities of forest fragments (FF) in Alter do Chão, eastern Brazilian Amazonia. The study sample consisted of 25 FF and nine continuous forest (CF) sites. We compared plant density and species richness between site categories by t-tests, analyzed the differences in composition by cluster analysis, and assessed the effect of fragment size and distance to CF on the basal area and diameter of FF assemblages by linear regression. Individual trees and shrubs with DBH ≥1.27 cm were measured in 2x250 m plots. 17,078 individuals were recorded - 75.32% in FF and 24.68% in CF, comprising 475 species, 216 genera and 64 families. Myrtaceae and Fabaceae were the most abundant families in both FF and CF. Average species richness in FF and CF was statistically different. The 20 species with the highest importance values were similar in FF and CF. The average plant diameter was similar in FF and CF, suggesting that both are "mature" forests composed of thin individuals. Average diameter and total basal area showed a negative relationship with distance to CF and fragment area, respectively. Similarity analysis revealed two groups, one composed exclusively of portions of fragmented forest. Fragments and continuous forest differed in species composition, but were similar in structure. Diameter distribution in fragments was similar to that of primary forests.
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Martínez-Natarén, Daniela A., Víctor Parra-Tabla i Miguel A. Munguía-Rosas. "Genetic diversity and structure of the treeManilkara zapotain a naturally fragmented tropical forest". Journal of Tropical Ecology 33, nr 4 (lipiec 2017): 285–94. http://dx.doi.org/10.1017/s0266467417000268.
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Abstract:Forest fragmentation, habitat loss and isolation may have a strong effect on biodiversity in tropical forests. This can include modification of the genetic diversity and structure of plant populations. In this study, we assessed the genetic diversity and structure of the treeManilkara zapotain 15 naturally formed fragments of semi-evergreen tropical forest, as well as in an adjacent continuous forest for comparison. Forest fragments were scattered within a matrix of wetlands and were highly variable in terms of size and degree of isolation. The naturally fragmented populations ofM.zapotahad slightly less allelic diversity (Ar: 3.4) than those of the continuous forest (Ar: 3.6), when corrected for sample size. However, populations in the fragments and continuous forest had very similar heterozygosity levels (HE: 0.59 in both cases). Low levels of genetic differentiation were observed among populations (FST: 0.026) and genetic structure was not consistent with isolation by distance, indicating high levels of gene flow. Genetic diversity was not explained by fragment size or degree of isolation. The relatively high genetic diversity and low inter-population genetic differentiation observed inM. zapotamay be the result of long-distance pollen and seed dispersal, as well as the high proximity among patches.
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Virgós, Emilio. "Factors affecting wild boar (Sus scrofa) occurrence in highly fragmented Mediterranean landscapes". Canadian Journal of Zoology 80, nr 3 (1.03.2002): 430–35. http://dx.doi.org/10.1139/z02-028.
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This paper is an analysis of the effects of forest fragmentation on wild boar (Sus scrofa) occurrence in coarse-grained fragmented landscapes (<20% forestscrubland cover on a landscape scale; N = 140 forest fragments, four regions) in central Spain. Occurrence was examined in relation to forest size, isolation, habitat quality, and region. Wild boar occurrence was mainly explained by the location of the forest fragments on the northern or southern plateau. Wild boars were more abundant on the northern plateau than on the southern plateau. In addition, wild boars are more frequent in large forest fragments adjacent to other large forests near mountains or riparian woodlands. The percent presence of wild boars in fragments varied among the four regions sampled (regional effect). Although wild boars occurred more frequently in large than in small forests, this pattern was less pronounced than that found in badgers (Meles meles), roe deer (Capreolus capreolus), and stone martens (Martes foina) and similar to that found in red foxes (Vulpes vulpes). The spatial distribution of wild boars may be affected by forest fragmentation despite their typical generalist life-history traits and potential use of agricultural areas as food habitats. These results support the idea that landscape pattern (degree of fragmentation and grain pattern) may be a determinant of species' abundance and distribution in fragmented landscapes.
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De Santo, Toni L., Mary F. Willson, Kathryn E. Sieving i Juan J. Armesto. "Nesting Biology of Tapaculos (Rhinocryptidae) in Fragmented South-Temperate Rainforests of Chile". Condor 104, nr 3 (1.08.2002): 482–95. http://dx.doi.org/10.1093/condor/104.3.482.
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Abstract We studied the effect of forest fragmentation on the nesting biology and reproductive success of three species of tapaculos (Rhinocryptidae) in relation to forest size, edge effects, and disturbance from livestock or logging over a 6-year period (1993–1999) in Chilean temperate rainforest. Overall, Mayfield nest success (n = 360) among the three species ranged from 64% to 85%, and predation accounted for 64% of nest losses. Considering all types of losses, nest mortality was similar in fragmented and unfragmented forest, but predation was higher in fragmented forest. Successful nest sites of the Chucao Tapaculo (Sclerochilus rubecula; the species with the largest sample size) were nearer forest edges, better concealed, closer to the ground, and had longer entrance tunnels, on average, than depredated nests. Reuse of nest sites by chucaos was more common in forest fragments with livestock or logging than in undisturbed forests, but reuse was independent of forest size. Success of second broods was lower in reused nest sites than in new nest sites. Nestling growth in fragmented forest and forest with livestock or logging activity was similar to that in unfragmented and undisturbed forest. Clutch size was typically two, but birds nesting at low densities in forest fragments often laid three-egg clutches following a nest failure. In addition to negative effects of forest fragmentation during nesting (greater use of less-successful nest sites, higher nest predation), there was an indication that early juvenile survival was lower in forest fragments. Biología de Nidificación de Tapaculos (Rhinocryptidae) en la Selva Lluviosa Templada Fragmentada de Chile Resumen. Durante seis años (1993–1999) estudiamos los efectos de la fragmentación de bosques templados del sur de Chile sobre la biología y éxito reproductivo de tres especies de tapaculos (Rhynocriptidae) en relación al tamaño del fragmento boscoso, efectos de borde, y perturbación por ganado doméstico y tala de árboles. En general, el éxito de nidificación (n = 360) estimado por el método Mayfield para las tres especies varió entre 64% y 85%. La depredación explicó un 64% de las pérdidas de nidos. Tomando en cuenta todas las causas de mortalidad, la pérdida de nidos fue equivalente en bosques fragmentados y continuos, pero la depredación fue mayor en bosques fragmentados. Los sitios de nidificación exitosa de Sclerochilus rubecula (chucao; la especie con el mayor número de muestras) se encontraron, en promedio, más cerca de los bordes, mejor ocultos, más cerca del suelo y con túneles de entrada más largos que los nidos depredados. La reutilización de nidos por parte de los chucaos fue más común en los fragmentos perturbados por tala de árboles o pisoteo de ganado que en bosques no perturbados, pero fue independiente del tamaño del fragmento. El éxito de la segunda nidada fue menor en nidos re-utilizados que en nidos nuevos. El crecimiento de los juveniles en los nidos ubicados en bosques fragmentados y perturbados fue similar al del observado en los bosques continuos no perturbados. El número de crías de los chucaos fue típicamente dos, pero las aves que anidaron en fragmentos boscosos, donde la densidad local era baja, frecuentemente pusieron tres huevos por nido luego de un intento de nidificación fallido. Además de los efectos negativos de la fragmentación del bosque durante el período de nidificación (i.e., mayor uso de sitios de nidificación inseguros, mayor depredación de nidos), la sobrevivencia temprana de los juveniles sería menor en fragmentos boscosos.
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Delciellos, Ana C., Marcus V. Vieira, Carlos E. V. Grelle, Priscilla Cobra i Rui Cerqueira. "Habitat quality versus spatial variables as determinants of small mammal assemblages in Atlantic Forest fragments". Journal of Mammalogy 97, nr 1 (30.10.2015): 253–65. http://dx.doi.org/10.1093/jmammal/gyv175.
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Abstract Fragment size, isolation, and matrix properties have received considerable attention as predictors of species richness, abundance, and composition in habitat patches. However, measurements of habitat attributes or habitat quality are more directly related to the proximate effects of habitat fragmentation and may be more determinant of assemblages than traditional explanatory variables at local scales. We determine how habitat structure in fragments—a measure of habitat quality—compares to fragment size, isolation, and matrix properties as determinants of richness, abundance, and composition of non-volant small mammals in a fragmented landscape of Atlantic Forest. Small mammals were surveyed once in 25 fragments in the Macacu River watershed, Rio de Janeiro, Brazil, from 1999 to 2001 and 2005 to 2009. A total of 83 candidate models were formulated and compared by Akaike Information Criteria. Habitat structure was one of the main determinants of small mammal assemblages in fragments, as important as fragment isolation for species composition and climatic season for species richness. Rodents were more abundant in fragments with increased overstory and understory vegetation density and more fallen logs. The contrary pattern was found for overall species richness and for species of terrestrial habit, which were more abundant in fragments with more open forest: decreased overstory and understory vegetation density and less fallen logs. Habitat quality in fragments may be a more important determinant of assemblages of small mammals and other vertebrates than previously considered in landscape and land use studies. O tamanho e isolamento dos fragmentos e as propriedades da matriz têm recebido considerável atenção como preditores da riqueza, abundância e composição de espécies em manchas de habitat. Entretanto, medidas dos atributos do habitat ou da qualidade do habitat são mais diretamente relacionadas aos efeitos imediatos da fragmentação de habitat, e seriam mais determinantes das comunidades do que as variáveis explicativas tradicionais. Determinamos como a estrutura do habitat nos fragmentos—uma medida da qualidade do habitat—se compara ao tamanho e isolamento dos fragmentos, e às propriedades da matriz como determinantes da riqueza, abundância e composição de espécies de pequenos mamíferos não-voadores em uma paisagem fragmentada de Mata Atlântica. Os pequenos mamíferos foram amostrados uma vez em 25 fragmentos na Bacia do Rio Macacu, Rio de Janeiro, Brasil, de 1999 a 2001 e de 2005 a 2009. Um total de 83 modelos foram formulados e comparados utilizando o Critério de Informação de Akaike. A estrutura do habitat foi um dos principais determinantes das comunidades de pequenos mamíferos nos fragmentos de mata, tão importante quanto o isolamento entre fragmentos para a composição de espécies e os efeitos das estações climáticas sobre a riqueza de espécies. Os roedores foram mais abundantes nos fragmentos com estratificação vertical e sub-bosque mais densos e com maior presença de troncos caídos. O padrão contrário foi encontrado para a riqueza total de espécies e para espécies de hábito terrestre, que foram mais abundantes em fragmentos com estratificação vertical e sub-bosque menos densos e menor presença de troncos caídos. A qualidade do habitat em fragmentos pode ser determinante das comunidades de pequenos mamíferos e outros vertebrados, mais importante do que considerado previamente em estudos de paisagens e uso da terra.
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Guariz, Hugo Roldi, i Francisco Roldi Guariz. "Avaliação do Tamanho e Forma de Fragmentos Florestais por Meio de Métricas de Paisagem para o Município de São Roque do Canaã, Noroeste do Estado do Espírito Santo". Revista Brasileira de Geografia Física 13, nr 5 (29.07.2020): 2139. http://dx.doi.org/10.26848/rbgf.v13.5.p2139-2153.
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Após um século de intensas produções agropecuárias, baseadas na monocultura do café, pecuária bovina extensiva e intenso ciclo madeireiro, as florestas do município de São Roque do Canaã se restringiram a pequenos fragmentos isolados, rodeados por ambientes não florestados. Mediante tal constatação, objetivou-se realizar o levantamento da cobertura florestal e caracterizar os fragmentos florestais localizados em São Roque do Canaã/ES utilizando métricas de ecologia de paisagem com uso de Sistema de Informação Geográfica (SIG), atrelado a uma análise ambiental desses fragmentos. Tais objetivos foram alcançados através da quantidade e frequência de classe de tamanhos dos fragmentos, Índice de Diversidade de Patton (DI), Índice de circularidade (C) e o Índice Perimetral (IP). Com base nos resultados, concluímos que o município possui 17,6% de sua área coberta por florestas, sendo que deste total, 67,7% possui área inferior a 3 ha e 91,8% possuem área inferior a 15 ha. Por meio do mapeamento dos fragmentos florestais, verificamos que os fragmentos tendem para formatos irregulares com bordas dentadas, correspondendo a 49% do total. Cerca de 76% dos fragmentos tendem para formatos alongados e isolados, o que contribui para a perda de biodiversidade. Conclui-se que a vegetação florestal remanescente encontra-se fragmentada e a maioria dos fragmentos florestais observados apresentam tamanho considerado insatisfatório para manter a estabilidade e a autossustentabilidade ambiental. Evaluation of the Size and Shape of Forest Fragments Using Landscape Metrics for the Municipality of São Roque do Canaã, Northwest of Espírito Santo State A B S T R A C TAfter a century of intense coffee monoculture-based agricultural production, extensive cattle ranching and intense timber cycle, the forest cover of São Roque do Canaã (ES) were reduced to small, isolated fragments surrounded by non-forested environments. From this observation, this paper aims carrying out a survey of the forest cover and characterize the forest fragments located in São Roque do Canaã by metrics of landscape ecology approach, using the Geographic Information System (GIS) linked to the environmental analysis of the fragments. Main data was obtained by calculating the quantity and frequency of the size class of the fragments, Patton's Diversity Index (DI), Circularity Index (C) and the Perimeter Index (IP). We concluded that the municipality has 17.6% of its area covered by forests, of which 91.8% is 15 ha or smaller, and 67.7% is lesser than 3 ha. The fragments tend to irregular shapes with jagged edges, with a tendency to elongated shapes, characteristics that foster the deleterious consequences of the edge effect. In conclusion, the remaining forest vegetation is highly fragmented, mainly composed by very small and isolated fragments, which is considered unsatisfactory to maintain stability and environmental self-sustainability. Actions to recover vegetation, such as the implementation of ecological corridors, the creation of conservation units and agroforestry production systems are recommended ways to increase the percentage of forests in São Roque do Canaã.Keywords: Fragmentation, landscape ecology, edge effect, biodiversity, deforestation.
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Santiago, Graziele Da Silva, B. R. F. Campos i Carla Rodrigues Ribas. "How does landscape anthropization affect the myrmecofauna of urban forest fragments?" Sociobiology 65, nr 3 (2.10.2018): 441. http://dx.doi.org/10.13102/sociobiology.v65i3.3042.
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We evaluate whether landscape variables surrounding urban remnant forest fragments influence ant diversity and its components in urban areas. The study was conducted in six riparian forest fragments in midwestern Minas Gerais State, Brazil, by sampling epigaeic and arboreal ants. Arboreal ants respond to fragmente isolation with changes in alpha, beta and gamma diversities. Isolation likely hinders dispersion and re-colonization such that the more isolated a fragment is, the less likely that new species arrive there. On other hand, epigaeic diversity did not show any response to variables of the surroundings or fragments, probably because natural periodic floods constitute a more severe disturbance for these ants. In addition, throughout the process of urbanization, anthropogenic improvements, such as paving, that prevent the natural percolation of water, increase the flooding of riparian soil. Arboreal ant species composition responds to percentage of urban area, fragment area and distance from the urban center, while epigaeic ants respond only to fragment area and percentage of urban area. We believe that even with the loss of species diversity and anthropogenic influences on fragments within urban centers, these areas are still important for species conservation. We also suggest the development of environmental protection projects for riparian áreas within urban centers, including investments in ecological corridors connecting fragments and public policies seeking to preserve these areas.
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Cicuzza, Daniele, i Christos Mammides. "Soil, Topography and Forest Structure Shape the Abundance, Richness and Composition of Fern Species in the Fragmented Tropical Landscape of Xishuangbanna, Yunnan, China". Forests 13, nr 9 (9.09.2022): 1453. http://dx.doi.org/10.3390/f13091453.
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Understanding how forest fragment size, topography, forest structure, and soil properties affect plant diversity remains a crucial question in conservation biology, with ferns often being understudied. To address this knowledge gap, we surveyed the abundance, species richness, and composition of ferns in a tropical landscape in south China using 75 sites in 42 forest fragments. We then used a multi-model inference approach to assess whether fern abundance, richness, and composition were better explained by (a) fragment size, (b) topography (slope, aspect), (c) forest structure (tree basal area, light availability), or (d) soil properties (pH, Carbon, Nitrogen, Phosphorous, Calcium, Magnesium, water availability, and proportion of clay, silt, and sand). We also conducted a nestedness analysis to examine whether the composition of the fern communities in smaller fragments (0.4–1 km²) differed or represented a subset of the communities found in larger fragments (e.g., >10 km²). We found that (a) fern abundance was mostly influenced by soil properties, slope, and aspect, (b) fern species richness by soil properties and slope, and (c) fern species composition by forest structure, specifically, tree basal area. We also found that fern species composition was not nested in the landscape, suggesting that smaller forest fragments had different communities from larger fragments. Our results suggest also that soil properties play an important role in maintaining fern abundance and diversity and therefore protecting soil can help conserve ferns in fragmented landscapes.
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Roik, Mailson, Afonso Figueiredo Filho, Tiago Grespan, Thiago Floriani Stepka i Rodrigo Otávio Veiga de Miranda. "DINÂMICA DA FLORÍSTICA E DA ESTRUTURA HORIZONTAL EM UM FRAGMENTO DE FLORESTA OMBRÓFILA MISTA MONTANA". Nativa 7, nr 6 (11.11.2019): 748. http://dx.doi.org/10.31413/nativa.v7i6.7835.
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Este trabalho objetivou analisar as alterações na composição florística e estrutura horizontal em um fragmento de Floresta Ombrófila Mista, localizado na Floresta Nacional (FLONA) de Irati, Paraná, Brasil, assim como compará-lo quanto à florística e estrutura de outros fragmentos florestais localizados em FLONAs da região sul do país. Todos os indivíduos com diâmetro à altura do peito maior ou igual a 10 cm (DAP ≥ 10 cm) foram identificados e mensurados ao longo de nove anos. A floresta apresentou elevada riqueza de espécies ao longo do período de monitoramento e pequenas alterações em relação a sua composição florística e estrutura horizontal. As divergências florístico-estruturais entre os fragmentos utilizados para comparação com o presente estudo se devem principalmente à grande heterogeneidade intrínseca a esta fitofisionomia, como também ao aumento da dissimilaridade em função do distanciamento geográfico.Palavras-chave: análise multivariada; composição florística; fitossociologia; Floresta com Araucária. DYNAMICS OF FLORISTIC AND HORIZONTAL STRUCTURE IN A FRAGMENT OF MONTANE MIXED OMBROPHYLOUS FOREST ABSTRACT: The aim of this research was to analyze the changes on the floristic composition and horizontal structure in an Araucaria Forest fragment, located in the Irati National Forest (FLONA), Paraná State, Brazil, as well as comparing it to the floristic and structure of other forest fragments located in FLONAs of the southern region of the country. All the individuals with diameter at breast height equal or larger than 10 cm (DBH ≥ 10 cm) were identified and measured for nine years. The forest presented a high number of species during the monitoring period and few changes in floristic composition and horizontal structure. The floristic-structural divergences among the fragments used for comparison with the present study are mainly due to the great heterogeneity intrinsic to this phytophysiognomy, as well as to the increase of dissimilarity due to geographic distance.Keywords: Araucaria forest; floristic composition; multivariate analysis; phytosociology.
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Nehru, Prabakaran, G. Gnanasekaran, N. Muthu Karthick i D. Narasimhan. "Angiosperms of Nanmangalam Reserve Forest, an urban forest in Metropolitan Chennai, India". Check List 8, nr 1 (1.02.2012): 057. http://dx.doi.org/10.15560/8.1.057.
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Humans have altered the forests of urban regions drastically, thereby reducing the original forests to isolated fragments. Such fragments may contain remnants of the original vegetation. Nanmangalam Reserve Forest (NRF), located in the Metropolitan Chennai, Tamil Nadu, India, is an example of such a forest fragment, covering an area of 321 ha. A total of 449 angiosperm species belonging to 313 genera representing 83 families were recorded from NRF. Amongst the species, 79% were dicots and 21% were monocots. The most genera/species rich families were Fabaceae (37/69) and Poaceae (34/52). The species rich genera included Cassia (10), Crotalaria (7), Erogrostis, Hedyotis and Phyllanthus (6 each). Six endemic species were recorded. This diversity amidst a rapidly expanding city has to be protected in order to enable the conservation agenda of urban areas.
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Klass, Keren, Sarie Van Belle, Alvaro Campos-Villanueva, Fernando Mercado Malabet i Alejandro Estrada. "Effects of variation in forest fragment habitat on black howler monkey demography in the unprotected landscape around Palenque National Park, Mexico". PeerJ 8 (10.08.2020): e9694. http://dx.doi.org/10.7717/peerj.9694.
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Habitat loss and fragmentation are leading threats to biodiversity today, and primates are particularly vulnerable to anthropogenic habitat disturbance. However, few studies have examined how differential effects of variation in forest fragment characteristics on males and females in a primate population may affect demography and population persistence. We quantified the effects of variation in forest fragment characteristics on the within-fragment demography of black howler monkeys (Alouatta pigra) in forest fragments around Palenque National Park, Mexico, and how these effects differed between adult males and females. We quantified forest loss in the landscape between 2000 and 2017, and used a redundancy analysis to examine the effects of 15 variables quantifying fragment dimensions, forest composition and physical structure, and isolation on fragment population size and density, the proportion of adult males and females in the fragment population, and the mean number of adult males and females per group in 34 fragments (N = 393 monkeys). We hypothesized that (i) population size is positively correlated with fragment area, while population density is negatively correlated, and (ii) the composition of fragment populations results from differential effects of fragment variables on adult males and females. Forest cover decreased by 23.3% from 2000 to 2017. Our results showed a significant effect of fragment variables on population demography in fragments, accounting for 0.69 of the variance in the demographic response variables. Population size increased with fragment area and connectivity, while density decreased. Larger, less isolated fragments with better connectivity, characteristics indicative of abundant secondary growth, and those with more diverse vegetation but lower Simpson’s evenness indices tended to have more adult females per group and a higher proportion of adult females in the population. In contrast, fragments that were largely similar in characteristics of forest composition and structure, but that were more isolated from nearby fragments, had more adult males per group and a higher proportion of adult males. These results may stem from black howler females preferentially remaining in natal groups and fragments when possible, and dispersing shorter distances when they disperse, while males may be more likely to disperse between fragments, traveling longer distances through the matrix to more isolated fragments. These differential effects on males and females have important conservation implications: if females are more abundant in larger, less isolated fragments, while males are more abundant in more isolated fragments, then to effectively conserve this population, both landscape connectivity and fragment areas should be maintained and increased.
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Marchesan, Juliana, Rudiney Soares Pereira, Elisiane Alba i Letícia Daiane Pedrali. "Spatial Analysis of Forest Fragmentation in the Atlantic Forest Bioma Areas". Journal of Agricultural Science 10, nr 12 (15.11.2018): 294. http://dx.doi.org/10.5539/jas.v10n12p294.
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The goal of this work was to calculate landscape ecology metrics using the R language, allowing the analysis of forest fragments under the Atlantic Forest domain located in the sub-basin of Arroio Jaquirana, Rio Grande do Sul, Brazil. For the mapping of the forest fragments, we used images from the REIS/RapidEye sensor dated 2016, and the classification was supervised through the Bhattacharya algorithm. The fragments were analyzed in seven size classes, to separate them and to calculate the landscape metrics it was used R language. The results attained demonstrated that the native forest occupied 34.01% of the study area, covering a total of 1,995 fragments, of which 93.43% were less than 5 ha. The highest values of edge and perimeter-area ratio were found in the small fragments indicating a greater edge effect, with the central areas of these remnants being exposed to the external matrix effects. Thus, it is concluded that the Atlantic Forest is highly fragmented and is extremely important to establish measures to minimize the effects and/or increase the connectivity between the fragments through ecological corridors using the smaller fragments, in addition, it makes necessary the development of public policies and research for the management of the region in order to preserve the remnants.
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Walter, Scott T., Luke Browne, Juan Freile, Nelson González, Julio Loor, Michael Darkes, Thomas W. Gillespie i Jordan Karubian. "Nocturnal bird diversity in forest fragments in north-west Ecuador". Journal of Tropical Ecology 33, nr 6 (listopad 2017): 357–64. http://dx.doi.org/10.1017/s0266467417000372.
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Abstract:Habitat preferences and response to habitat conversion remain under-studied for many groups in the tropics, limiting our understanding of how environmental and anthropogenic factors may interact to shape patterns of diversity. To help fill this knowledge gap, we surveyed nocturnal birds such as owls, nightjars and potoos through auditory transect surveys in 22 forest fragments (2.7 to 33.6 ha) in north-west Ecuador. We assessed the relative effect of habitat characteristics (e.g. canopy height and openness, and density of large trees) and fragment attributes (e.g. area, altitude and proportion of surrounding forest cover) on species richness and community composition. Based on our previous work, we predicted that nocturnal bird richness would be highest in relatively larger fragments with more surrounding forest cover. We recorded 11 total species with an average ± SD of 3.4 ± 1.4 (range = 2–7) species per fragment, with higher richness in fragments that were larger, at lower altitudes, and characterized by more open canopies. Nocturnal bird community similarity was not significantly correlated with any measured environmental variable. These results indicate that both landscape (e.g. altitude) and fragment-specific (e.g. size, forest structure) attributes are likely to interact to shape patterns of diversity among this poorly known but ecologically important guild in fragmented tropical landscapes.
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Zambrano, Jenny, Rosamond Coates i Henry F. Howe. "Seed predation in a human-modified tropical landscape". Journal of Tropical Ecology 31, nr 4 (8.06.2015): 379–83. http://dx.doi.org/10.1017/s026646741500019x.
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Abstract:Contemporary defaunation of fragmented forests potentially alters patterns of seed predation and dispersal. Alternatively, the remaining fauna may compensate for missing animals, resulting in equivalent rates of seed dispersal and predation. In the Los Tuxtlas region of southern Mexico, populations of large terrestrial fruit-eating mammals are diminished or absent from many forest remnants. This study reports fruit removal and seed predation patterns of Poulsenia armata (Moraceae), in forest fragments and a continuous forest (LTBS). Contrary to expectation, we found no differences in seed predation (mean ± SD) between LTBS (7.2 ± 1.8 seeds per station) and forest fragments (5.6 ± 1.1). However more fruits were removed in the LTBS (11.4 ± 0.9 fruits per station) than in forest fragments (8.1 ± 0.8). Animal activity, recorded by camera traps, differed between animal guild with fewer seed dispersers in forest fragments (mean = 0.43 ± 0.02 photos wk−1) than in the LTBS (mean = 0.68 ± 0.05). Fruits and seeds attracted many species of mammal (n = 12) in both habitats, indicating substantial redundancy. Remnant forest patches in the Los Tuxtlas landscape retain great ecological value, both as refuges for mammals and habitats for trees, such as P. armata.
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Gálvez, Nicolás, Felipe Hernández, Jerry Laker, Horacio Gilabert, Robert Petitpas, Cristián Bonacic, Alessandro Gimona, Alison Hester i David W. Macdonald. "Forest cover outside protected areas plays an important role in the conservation of the Vulnerable guiña Leopardus guigna". Oryx 47, nr 2 (kwiecień 2013): 251–58. http://dx.doi.org/10.1017/s0030605312000099.
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AbstractHabitat loss and fragmentation are affecting populations of forest dwelling mammalian carnivores worldwide. In southern Chile, a biodiversity hotspot, anthropogenic activities have resulted in high loss of native forest cover. The guiña, or kodkod cat, Leopardus guigna is a small forest-dwelling felid with a narrow range in the temperate forest of southern Chile. The few existing studies of the species have suggested that it is almost exclusively restricted to large tracts of native forest. This paper reports a study in the temperate forest within a fragmented Andean piedmont landscape which demonstrates that smaller forest fragments in the farmland matrix are playing a key role in the persistence of the guiña. We estimated occupancy in both continuous native forest and remnant forest fragments and, with single-species/single-season models, evaluated the extent to which forest cover, habitat type and proximity to protected areas have a modulating effect on occupancy. A continuous survey during 2008–2009, in three seasons of 90–100 days each, accumulated 6,200 camera trap days and returned 47 photographs of guiña. Total detection in fragments was higher than in continuous forests, with detection confirmed in almost 70% of studied fragments. We found that probability of a site being occupied significantly increased with forest cover (adult/secondary forest, scrubland) and probability was low (< 0.2) in sites with < 50% of surrounding forest cover. Our study highlights the importance of remnant forest fragments in the mosaic of extensive agriculture for the spatial dynamics of a guiña population and hence for the future conservation of the species.
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Magalhaes, Ivo Augusto Lopes, Carlos Roberto Lima Thiago i Alexandre Rosa Dos Santos. "Identificação de Fragmentos Florestais Potencias para a delimitação de Corredores Ecológicos na bacia hidrográfica do Rio Itapemirim, ES por meio técnicas de Sensoriamento Remoto". Revista Brasileira de Geografia Física 13, nr 2 (7.04.2020): 595. http://dx.doi.org/10.26848/rbgf.v13.2.p595-612.
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Os corredores ecológicos surgem como alternativa para mitigar os efeitos da fragmentação florestal permitindo entre eles o fluxo gênico de fauna e flora e a recolonização de áreas degradadas. Diante do exposto o presente estudo teve como objetivo, identificar para a bacia hidrográfica do rio Itapemirim, ES, por meio de metodologia desenvolvida em Sistemas de Informações Geográficas, a delimitação de corredores ecológicos que propiciem a interligação de fragmentos florestais, identificados mediante análise das métricas da paisagem como fragmentos florestais com atributos espaciais, que sugerem maior conservação. A metodologia consistiu no mapeamento dos fragmentos florestais por meio de técnicas de classificação supervisionada utilizando imagem do satélite LANDSAT 8 OLI, obtidas junto ao Instituto Nacional de Pesquisas Espaciais. Realizou-se o cálculo dos índices de ecologia, por meio do software ArcGis 10.2, com a extensão de domínio público V-LATER 2.0. Identificou-se 11.749 fragmentos florestais, que representam 22% de cobertura florestal na bacia hidrográfica. Os fragmentos pequenos (< 5 ha) foram encontrados em maior número, 8.394, seguidos pelos fragmentos de tamanho médio (5 a 50 ha), 2.995, e grandes (> 50 ha), 360. O número de fragmentos apresentaram relação inversa com sua contribuição na área. O bioma Mata Atlântica presente na bacia hidrográfica do rio Itapemirim, é representado, em sua maioria, por fragmentos florestais pequenos, menores que 5 ha, indicando um alto grau de fragmentação. Identification of Forest Fragments Potential for the delimitation of Ecological Corridors in the Itapemirim, ES River Basin through Remote Sensing techniques A B S T R A C TEcological corridors emerge as an alternative to mitigate the effects of forest fragmentation, allowing for the gene flow of fauna and flora and the recolonization of degraded areas. Given the above, the present study aimed to identify, for the Itapemirim river basin, ES, through a methodology developed in Geographic Information Systems, the delimitation of ecological corridors that allow the interconnection of forest fragments, identified through the analysis of the metrics. landscape as forest fragments with spatial attributes, which suggest greater conservation. The methodology consisted of mapping forest fragments by supervised classification techniques using LANDSAT 8 OLI satellite imagery, obtained from the National Institute for Space Research. Ecology indices were calculated using the ArcGis 10.2 software, with the public domain extension V-LATER 2.0. A total of 11,749 forest fragments were identified, representing 22% of forest cover in the watershed. Smaller fragments (<5 ha) were found in larger numbers, 8,394, followed by medium sized fragments (5 to 50 ha), 2,995, and large fragments (> 50 ha), 360. The number of fragments was inversely related to their size. contribution in the area. The Atlantic Forest biome present in the Itapemirim river basin is mostly represented by small forest fragments, smaller than 5 ha, indicating a high degree of fragmentation.Keywords: Indexes of landscape ecology, Atlantic Forest, Geoprocessing.
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MacIntosh, T., B. J. M. Stutchbury i M. L. Evans. "Gap-crossing by Wood Thrushes (Hylocichla mustelina)in a fragmented landscape". Canadian Journal of Zoology 89, nr 11 (listopad 2011): 1091–97. http://dx.doi.org/10.1139/z11-090.
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We used radio-telemetry to study the movement patterns of Wood Thrushes ( Hylocichla mustelina (J.F. Gmelin, 1789)) occupying small forest fragments (<5 ha) to examine gap-crossing between fragments and edge use within fragments. We found that 82% (8/11) of males and 33% (2/6) of females made at least one foray off of its resident forest fragment and we documented a total of 26 off-fragment forays (n = 79 h tracking). Males spent, on average, 23.5% of their time off their fragment, while females were gone 12.8% of the time tracked. Most forays were >150 m in distance and foray rate to adjacent fragments declined with increasing gap width. Males on fragments spent more time off their territory (23.5%) and traveled farther (392 m) than males occupying territories within a continuous forest (4.8% and 99 m, respectively). In fragments, 10 out of 17 individuals spent >80% of their time within 20 m of the fragment edge and edge use was significantly more than expected based on the amount of edge available in each fragment. This study adds to the growing evidence for migratory songbirds that during the breeding season, forest fragmentation may increase rather than impede daily movements.
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Solís-Hernández, Wendy, i Eric-J. Fuchs. "Effective gene flow patterns across a fragmented landscape in southern Costa Rica for Symphonia globulifera (Clusiaceae); a species with mobile seed and pollen dispersers". Revista de Biología Tropical 67, nr 2SUPL (13.05.2019): S95—S111. http://dx.doi.org/10.15517/rbt.v67i2supl.37209.
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In tropical trees, forest fragmentation has been shown to affect mating and gene flow patterns. Mobile dispersal vectors should be less sensitive to fragmented landscapes and may ameliorate the genetic effects of forest fragmentation on plant populations. To test this hypothesis, we analyzed gene flow patterns in Symphonia globulifera, a tropical tree species with highly mobile pollinators and seed dispersers in the Osa Peninsula in southern Costa Rica. We used microsatellites to study genetic diversity and realized gene flow patterns between a continuous forest and a forest fragment. We found high levels of genetic diversity in adults and seedlings at both sites. Parentage analyses suggest near-neighbor matings and frequent long-distance gene flow events. Half the progeny beneath an adult was not sired by that tree and the majority of established seedlings were the result of long-distance gene dispersal. Gene flow from the forest into the fragment was more common than from the fragment into the continuous forests. Despite long distance gene flow events, seedling spatial genetic structure was stronger and extended further in the forest fragment likely due to limited seed dispersal. We conclude that fragmentation affects gene flow in this tropical tree and may compromise its genetic diversity in forest fragments even for a species with mobile pollen and seed vectors.
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Wingate, Vladimir R., Felicia O. Akinyemi, Chima J. Iheaturu i Chinwe Ifejika Speranza. "A Remote Sensing-Based Inventory of West Africa Tropical Forest Patches: A Basis for Enhancing Their Conservation and Sustainable Use". Remote Sensing 14, nr 24 (9.12.2022): 6251. http://dx.doi.org/10.3390/rs14246251.
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The rate of tropical deforestation is increasing globally, and the fragmentation of remaining forests is particularly high in arable landscapes of West Africa. As such, there is an urgent need to map and monitor these remnant forest patches/fragments and so identify their multiple benefits and values. Indeed, recognizing their existence will help ensure their continued provision of ecosystem services while facilitating their conservation and sustainable use. The aim of this study is therefore to inventory and characterise the current extent and change of remnant forest patches of West Africa, using multi-source remote sensing products, time-series analyses, and ancillary datasets. Specifically, we collate and analyse descriptive and change metrics to provide estimates of fragment size, age, biophysical conditions, and relation to social-ecological change drivers, which together provide novel insights into forest fragment change dynamics for over four decades. We map forests patches outside protected areas with a tree cover ≥30%, a tree height of ≥5 m, an area ≥1 km2 and ≤10 km2. Appended to each patch are descriptive and change dynamics attributes. We find that most fragments are small, secondary forest patches and these cumulatively underwent the most forest loss. However, on average, larger patches experience more loss than smaller ones, suggesting that small patches persist in the landscape. Primary forest patches are scarce and underwent fewer losses, as they may be less accessible. In 1975 most patches were mapped as secondary, degraded forests, savanna, woodland, and mangrove, and relatively few comprised cropland, settlements, and agriculture, suggesting that new forest patches rarely emerged from arable land over the past 45 years (1975–2020), but rather are remnants of previously forested landscapes. Greening is widespread in larger secondary fragments possibly due to regrowth from land abandonment and migration to urban areas. Forest loss and gain are greater across fragments lying in more modified landscapes of secondary forests, while forest loss increases with distance to roads. Finally, larger forest patches harbour a denser tree cover and higher trees as they may be less impacted by human pressures. The number and extent of West African forest patches are expected to further decline, with a concurrent heightening of forest fragmentation and accompanying edge effects. Lacking any conservation status, and subject to increasing extractive demands, their protection and sustainable use is imperative.
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Anjos, Luiz dos. "Species richness and relative abundance of birds in natural and anthropogenic fragments of Brazilian Atlantic forest". Anais da Academia Brasileira de Ciências 76, nr 2 (czerwiec 2004): 429–34. http://dx.doi.org/10.1590/s0001-37652004000200036.
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Bird communities were studied in two types of fragmented habitat of Atlantic forest in the State of Paraná, southern Brazil; one consisted of forest fragments that were created as a result of human activities (forest remnants), the other consisted of a set of naturally occurring forest fragments (forest patches). Using quantitative data obtained by the point counts method in 3 forest patches and 3 forest remnants during one year, species richness and relative abundance were compared in those habitats, considering species groups according to their general feeding habits. Insectivores, omnivores, and frugivores presented similar general tendencies in both habitats (decrease of species number with decreasing size and increasing isolation of forest fragment). However, these tendencies were different, when considering the relative abundance data: the trunk insectivores presented the highest value in the smallest patch while the lowest relative abundance was in the smallest remnant. In the naturally fragmented landscape, time permitted that the loss of some species of trunk insectivores be compensated for the increase in abundance of other species. In contrast, the remnants essentially represented newly formed islands that are not yet at equilibrium and where future species losses would make them similar to the patches.
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Hernández-Pérez, Ezequiel, i Eloy Solano. "Effects of habitat fragmentation on the diversity of epiphytic orchids from a montane forest of southern Mexico". Journal of Tropical Ecology 31, nr 2 (28.11.2014): 103–15. http://dx.doi.org/10.1017/s0266467414000662.
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Abstract:Epiphytic orchids are very diverse in montane forests, but fragmentation modifies this diversity. Twenty fragments were quantified to evaluate the effects of fragmentation on the alpha and beta diversities of epiphytic orchids in a montane forest located in southern Mexico. The following factors were evaluated: area, core area, shape, edge density, Euclidean nearest-neighbour distance fragment and contrast index. In each fragment, two transects of 2 × 50 m were drawn, and the trees with a diameter at breast height ≥ 20 cm were recorded. In each tree, the orchid species present were identified and quantified. Twenty-three species of epiphytic orchid in 234 phorophytes corresponding to 20 species were recorded. The epiphytic orchid richness per tree and species turnover was different between the phorophytes. The edge density and the contrast index had significant effects on the alpha diversity, while the isolation of the fragments significantly affected the beta diversity. The edge density positively affected the alpha diversity of the epiphytic orchids, likely through microclimatic changes caused by fragmentation. Drought-tolerant species were common on the edges of the fragments, and shade-tolerant species established on the core area of the fragments. This pattern most likely depends on the ecological range of the taxa, which is crucial to their development and persistence in fragmented habitats.
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Cardoso-Leite, Eliana, Emerson Martins Arruda, Fabricio Macedo Galvani i Roberta Averna Valente. "Relationship between forest integrity, drainage headboards and patch-level metrics as subsidy for planning and conservation in fragmented Atlantic Forest areas". Research, Society and Development 11, nr 9 (20.07.2022): e33211931744. http://dx.doi.org/10.33448/rsd-v11i9.31744.
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Forests worldwide are essential goods for humanity as they provide support, provision, regulation, and cultural ecosystem services. In Brazil, the Atlantic Forest has lost much of its original cover, is currently represented by relatively small fragments in an anthropized matrix. Therefore, it is very relevant to analyze if forest fragments change in related the fragmentation of the original native vegetation and how they maintain their quality. This study aimed to analyze whether patch-level metrics are related to forest quality (biotic integrity) and whether relief features such as headboards are related to forest fragmentation patterns to provide subsidies for public planning and environmental conservation policies. The methodology involved mapping forest fragments (F) and drainage headboards (DH), calculating patch-level metrics (AREA, SHAPE, PROX), and the biotic integrity (BII) of the forest. Spearman's Correlation Coefficient was used to test the relationship between variables. The results showed a significative robust relationship between AREA and BII and significative medium relationship between SHAPE and DH, confirming partially the initial assumptions of the research. We concluded that the integrity of the forest fragment and the presence of drainage headboards must be considered in public planning and environmental conservation policies.
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Fernández-Juricic, Esteban. "Local and Regional Effects of Pedestrians on Forest Birds in a Fragmented Landscape". Condor 102, nr 2 (1.05.2000): 247–55. http://dx.doi.org/10.1093/condor/102.2.247.
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Abstract I assessed the effects of pedestrians on the distribution of forest bird species in wooded parks in the city of Madrid within and between fragments. Within fragments, increasing levels of pedestrians reduced species richness and overall abundance of individuals within circular plots. The abundance of foraging individuals of four species (Magpies Pica pica, Blackbirds Turdus merula, Starlings Sturnus unicolor, and Woodpigeon Columba palumbus) diminished when pedestrians walked near sampling plots, as well as their breeding densities in relation to increasing disturbance levels. Between fragments, after controlling for fragment size effects, pedestrian rate was negatively related to species richness in two breeding seasons. Species turnover was positively associated to mean pedestrian rate and inter-annual variability in pedestrian rate. At the species level, pedestrian rate negatively affected the probabilities of fragment occupation of 16 species beyond the effects of fragment size and isolation. Locally, the short-term behavioral responses to visitors may reduce the suitability of highly disturbed parks in such a way as to decrease breeding densities and the probabilities of fragment occupation and persistence. The effects of human disturbance in fragmented landscapes should be incorporated into management decisions as another relevant factor that may reduce habitat quality.
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Rheault, Héloïse, Pierre Drapeau, Yves Bergeron i Per-Anders Esseen. "Edge effects on epiphytic lichens in managed black spruce forests of eastern North America". Canadian Journal of Forest Research 33, nr 1 (1.01.2003): 23–32. http://dx.doi.org/10.1139/x02-152.
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We studied the spatial and temporal response of three epiphytic lichens (Bryoria spp., Evernia mesomorpha Nyl., and Usnea spp.) to edge effects in conifer forests of northwestern Quebec. Lichen abundance and substrate variables were sampled at four distances (5, 25, 50, and 100 m) from the edge in 15 edgeinterior transects in managed black spruce (Picea mariana (Mill.) BSP) forests. Responses to edge effects were assessed for short-term (13 years) and long-term (8 and 1623 years) periods. We also assessed the effect of forest fragment size on lichen abundance in 27 forest fragments ranging in size from 0.03 ha to >4 ha. We found a significant effect of distance to edge on mass of E. mesomorpha and Usnea spp. Lichen mass was lower in the first 50 m of edge compared with the forest interior (100 m). Size of forest fragments had no significant effect in any of the three lichens. However, mass of Usnea spp. was low in the seven smallest (<0.5 ha) fragments. Our results suggest that the response of epiphytic lichens to edge conditions could be used by forest managers as an indicator in determining the size of remnant stands that should be left to increase the proportion of interior forest habitat in harvested forest landscapes.
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Mello, José Marcio de, Henrique Ferraço Scolforo, Marcel Régis Raimundo, José Roberto Soares Scolforo, Antônio Donizette de Oliveira i Antônio Carlos Ferraz Filho. "ESTIMATING PRECISION OF SYSTEMATIC SAMPLING IN FOREST INVENTORIES". Ciência e Agrotecnologia 39, nr 1 (luty 2015): 15–22. http://dx.doi.org/10.1590/s1413-70542015000100002.
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The sampling technique commonly used in forest inventories is the systematic sampling. This study aimed to evaluate the estimator of the variance of the mean proposed by Cochran for a systematic sampling technique in forests with high and low percentages of the sampled area. The study areas comprised native vegetation in Minas Gerais. To assess the efficiency of the estimators in situations involving high sampling rates (determined as the percentage of the area sampled), a fragment where a census was conducted was used. The remaining fragments comprised situations involving low sampling rates, and for these fragments, inventory accuracy was determined using the Cochran estimator. As a result it was observed, in the fragment where the census was conducted, that the structure of the correlation coefficient proposed by Cochran remained approximately constant for the area, and to the extent that sampling rate reduced, the impact of the Cochran estimator on the inventory accuracy decreased. For the fragments with a low sampling rate, it could be inferred that the sampling rate was a key factor for the correlation proposed by Cochran to have an impact on the forest inventory accuracy. The use of this estimator is indicated for fragments with a sampling rate greater than 10% of the area.
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Zambrano, Jenny, Rosamond Coates i Henry F. Howe. "Effects of forest fragmentation on the recruitment success of the tropical tree Poulsenia armata at Los Tuxtlas, Veracruz, Mexico". Journal of Tropical Ecology 30, nr 3 (22.04.2014): 209–18. http://dx.doi.org/10.1017/s0266467414000108.
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Abstract:Recruitment success of individual plants is limited by an array of biotic and abiotic factors. Seedling survival may experience high mortality due to negative density dependence or altered microclimatic conditions. This study reports regeneration of Poulsenia armata (Moraceae), in the fragmented landscape of the Los Tuxtlas region in south-eastern Mexico. Density, survival and growth of seedlings (<1 y) and juveniles (<150 cm height) of P. armata were predicted to be significantly lower in forest fragments compared with extensive continuous forest. Contrary to expectation, density did not vary between habitats; however, we found twice the number of seedlings (n = 82) in forest fragments than in the continuous forest (n = 35). Forest fragments were associated with higher seedling densities close to adult trees. Unexpectedly, we found no evidence for negative density dependence in plant survival or growth. Survival and growth of P. armata were negatively impacted in forest fragments, with desiccation by warmer daily temperatures likely the cause of mortality, independent of density. Of the 111 individuals recorded in 2010 in forest fragments, 38% died over 2 y of census (n = 42), while 9% (n = 12) of the 127 individuals from the continuous forest died. Higher rates of mortality suggest that conditions in forest fragments are detrimental to seedling cohorts over time. Low juvenile recruitment jeopardizes persistence of P. armata, in fragmented populations of this rain-forest tree.
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Silva, Inês, Ricardo Rocha, Adrià López-Baucells, Fábio Z. Farneda i Christoph F. J. Meyer. "Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats". Diversity 12, nr 2 (7.02.2020): 67. http://dx.doi.org/10.3390/d12020067.
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Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages.
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Aguirre-Jaimes, Armando, Juan Carlos López-Acosta i Rodolfo Dirzo. "Tropical rainforest fragmentation affects plant species richness, composition and abundance depending on plant-size class and life history". Botanical Sciences 99, nr 1 (27.10.2020): 92–103. http://dx.doi.org/10.17129/botsci.2679.
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Background: Tropical rain forests have been impacted by land use change, leading to major deforestation and fragmentation. Understanding how fragmentation impacts plant communities is central for tropical conservation.
Questions: i) How does species richness vary across a range of fragment sizes, and does it vary with plant size-structure? ii) how are species composition and floristic similarity affected by forest fragmentation? iii) does habitat fragmentation affect the representation of species with different life-history and regeneration patterns?
Studied species: We sampled overall plant communities and calculated diversity metrics of mature-forest and light-demanding species, considering plants of different size-categories (defined by diameter at breast height, DBH).
Study site: This study was carried out at Los Tuxtlas, Veracruz, Mexico. An area originally dominated extensive evergreen tropical forest, but currently highly fragmented
Methods: We sampled plants in five forest fragments representing (2 - 36 ha), and a large patch of continuous forest (700 ha). Within each site we established ten-50 × 2 m transects and registered all woody plants with DBH > 1 cm.
Results: Species richness declined as fragment size became smaller. Such decline was significant considering all plants (DBH > 1.0 cm) but became non-significant as plant size-category increased (DBH > 2.5, or > 10 cm.). Small fragments had distinguishable assemblages compared to continuous forest and also a reduction in the representation of mature-forest species compared to light-demanding species.
Conclusions: Our findings confirm that fragmentation affects tropical plant species diversity, but the effect is differential, depending on plant size-category and life history.
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Jardim Leite, Raissa Iana, i João Carlos Ferreira Melo Júnior. "Reconhecimento de grupos funcionais em um fragmento de Mata Atlântica em Santa Catarina, Brasil". Revista Brasileira de Geografia Física 13, nr 2 (20.04.2020): 821. http://dx.doi.org/10.26848/rbgf.v13.2.p821-833.
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Compreender a complexidade funcional de fragmentos florestais urbanos é uma medida fundamental para a conservação da biodiversidade. O presente estudo reconheceu grupos funcionais de subosque num fragmento de Mata Atlântica localizado na cidade de Joinville, Santa Catarina. Foram avaliados atributos relacionados a ecologia de 31 espécies lenhosas. A estatística apresentou a formação de quatro grupos funcionais: G1 composto por Bathysa australis, espécie megafanerófita, mesófita e megáfila; G2 composto por 7 espécies secundárias tardias ou climáxicas; G3 integrado por 13 espécies de mesofanerófitas, polinizadas por abelhas e dispersas por aves; e G4 formado por 9 espécies macrófilas, secundárias iniciais e tardias. O fragmento apresentou baixa diversidade de grupos funcionais, com sobreposição destes em função da similaridade de requerimentos ecológicos, corroborando a tendência à redundância funcional em áreas florestais fragmentadas. Os resultados obtidos podem subsidiar medidas mitigatórias para a conservação e recuperação de áreas relictuais da Mata Atlântica. Recognition of functional groups in a fragment of Atlantic Forest in Santa Catarina, Brazil A B S T R A C TUnderstanding the functional complexity of urban forest fragments is a key measure for biodiversity conservation. The present study recognized functional groups of undersory in a fragment of Atlantic Forest located in Joinville city, Santa Catarina. Ecological attributes of 31 woody species were evaluated. The statistic presented the formation of four functional groups: G1 composed by Bathysa australis, megafanerophyte, mesophyte and megaphilic species; G2 composed by 7 late secondary or climactic species; G3 composed by 13 species of mesophanerophytes, pollinated by bees and dispersed by birds; and G4 formed by 9 macrophyll species, initial and late secondary. The fragment presented low diversity of functional groups, with overlapping of these due to the similarity of ecological requirements, corroborating the tendency to functional redundancy in fragmented forest areas. The results obtained can support mitigating measures for the conservation and recovery of relict areas of the Atlantic Forest.Key-words: functional ecology, rain forest, biodioversity conservation
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Zanette, Liana, i Bert Jenkins. "Nesting Success and Nest Predators in Forest Fragments: A Study Using Real and Artificial Nests". Auk 117, nr 2 (1.04.2000): 445–54. http://dx.doi.org/10.1093/auk/117.2.445.
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Abstract Area sensitivity in songbirds is commonly attributed to increased nest predation in forest fragments. In 1995 and 1996, we tested whether the nest predators and nesting success of an area-sensitive forest bird, the Eastern Yellow Robin (Eopsaltria australis), varied with fragment size, and we also conducted an artificial nest experiment. The study occurred in two small (55 ha) and two large (>400 ha) forest fragments in a matrix of agricultural land in New South Wales, Australia. Predation accounted for 95% of all failures of 282 robin nests, and the survival of robin nests was negatively correlated with how frequently we observed avian nest predators near nests (i.e. nest-predator activity). Of 461 artificial nests, 84% were depredated, nearly all (99%) by birds. Thus, birds were important predators of nests. The abundance, species richness, and activity of avian nest predators were not related to fragment size. Survival of robin nests averaged 19%; nests in small fragments had a 22% chance of producing at least one fledgling compared with 15% in large fragments, but the difference was not significant. Survival of artificial nests averaged 12% in both small and large fragments. Nest-predator activity accounted for the most variation (68%) in the fate of robin nests, followed by the cumulative density of open-cup nesters (16%). The placement of robin nests had no influence on nest fate. We conclude that nest predation was not area dependent and propose food supply as an alternative hypothesis to explain area sensitivity. We suggest that, rather than being related to fragment size, nest predation increases with decreasing forest cover in a landscape. Increased nest predation in fragmented compared with contiguous landscapes may lower the population viability of songbirds in a region, and hence regional numbers. Therefore, the spatial scale at which fragmentation influences nest predation and songbird populations must be considered carefully.
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Viswanathan, Ashwin, Jaboury Ghazoul, Ganesh Honwad, N. Arun Kumar i Robert Bagchi. "The effects of rainforest fragment area on the strength of plant–pathogen interactions". Biology Letters 15, nr 1 (styczeń 2019): 20180493. http://dx.doi.org/10.1098/rsbl.2018.0493.
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Pathogenic interactions between fungi and plants facilitate plant species coexistence and tropical rainforest diversity. Such interactions, however, may be affected by forest fragmentation as fungi are susceptible to anthropogenic disturbance. To examine how fragmentation affects fungus-induced seed and seedling mortality, we sowed seeds of six plant species in soils collected from 21 forest fragments. We compared seedling establishment in unmanipulated soils to soils treated with fungicides. Fungicides increased germination of Toona ciliata seeds and decreased mortality of Syzygium rubicundum and Olea dioica seedlings. The fungus-induced mortality of one of these species, S. rubicundum , decreased with decreasing fragment size, indicating that its interactions with pathogenic fungi may weaken as fragments become smaller. We provide evidence that a potential diversity-maintaining plant–fungus interaction weakens in small forest fragments and suggest that such disruptions may have important long-term consequences for plant diversity. However, we emphasize the need for further research across rainforest plant communities to better understand the future of diversity in fragmented rainforest landscapes.
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Barrantes, Gilbert, Diego Ocampo, José D. Ramírez-Fernández i Eric J. Fuchs. "Effect of fragmentation on the Costa Rican dry forest avifauna". PeerJ 4 (13.09.2016): e2422. http://dx.doi.org/10.7717/peerj.2422.
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Deforestation and changes in land use have reduced the tropical dry forest to isolated forest patches in northwestern Costa Rica. We examined the effect of patch area and length of the dry season on nestedness of the entire avian community, forest fragment assemblages, and species occupancy across fragments for the entire native avifauna, and for a subset of forest dependent species. Species richness was independent of both fragment area and distance between fragments. Similarity in bird community composition between patches was related to habitat structure; fragments with similar forest structure have more similar avian assemblages. Size of forest patches influenced nestedness of the bird community and species occupancy, but not nestedness of assemblages across patches in northwestern Costa Rican avifauna. Forest dependent species (species that require large tracts of mature forest) and assemblages of these species were nested within patches ordered by a gradient of seasonality, and only occupancy of species was nested by area of patches. Thus, forest patches with a shorter dry season include more forest dependent species.
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Ozório, Jefferson Matheus Barros, Jean Sérgio Rosset, Jolimar Antonio Schiavo, Camila Beatriz da Silva Souza, Paulo Guilherme da Silva Farias, Naelmo De Souza Oliveira, Roniedison Da Silva Menezes i Eloi Panachuki. "Physical fractions of organic matter and mineralizable soil carbon in forest fragments of the Atlantic Forest". Ambiente e Agua - An Interdisciplinary Journal of Applied Science 15, nr 6 (11.11.2020): 1. http://dx.doi.org/10.4136/ambi-agua.2601.
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This study determined the physical granulometric fractionation evaluated the mineralizable carbon within and around forest fragments of the Atlantic Forest biome located in the state of Paraná. Soil samples were collected at three three internal points of the fragments: the edge (E), the half radius (HR) and the center (CF); and one point in no-tillage system (NTS) areas around the fragments, in four replicates. The contents of total organic carbon (TOC), particulate fraction carbon (C-POM) and mineral fraction (C-MOM) were determined, and the %POM and %MOM and the stocks of POM (StockPOM) and MOM (StockMOM) were calculated, in addition to the indices: carbon stock index (CSI), lability (L), lability index (LI) and carbon management index (CMI), also evaluating CO2 emission, daily and accumulated. The highest TOC levels were observed in the CF point. The highest C-POM contents were observed in the E and CF points of fragment 1, in the CF point of fragment 2, and the highest C-MOM contents were expressed in the CF points of both fragments. CMI showed a distinct pattern among the fragments. The NTS areas showed lower C-CO2 emissions, with 39.8% and 28.3% less total emission compared to CF. The results of physical granulometric fractionation show the CF point favors the quality of SOM and the mineralizable carbon analysis indicated that the conversion of native areas into NTS compromises soil microbial activity.
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Bähner, K. W., K. A. Zweig, I. R. Leal i R. Wirth. "Robustness of plant–insect herbivore interaction networks to climate change in a fragmented temperate forest landscape". Bulletin of Entomological Research 107, nr 5 (10.02.2017): 563–72. http://dx.doi.org/10.1017/s0007485317000062.
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AbstractForest fragmentation and climate change are among the most severe and pervasive forms of human impact. Yet, their combined effects on plant–insect herbivore interaction networks, essential components of forest ecosystems with respect to biodiversity and functioning, are still poorly investigated, particularly in temperate forests. We addressed this issue by analysing plant-insect herbivore networks (PIHNs) from understories of three managed beech forest habitats: small forest fragments (2.2–145 ha), forest edges and forest interior areas within three continuous control forests (1050–5600 ha) in an old hyper-fragmented forest landscape in SW Germany. We assessed the impact of forest fragmentation, particularly edge effects, on PIHNs and the resulting differences in robustness against climate change by habitat-wise comparison of network topology and biologically realistic extinction cascades of networks following scores of vulnerability to climate change for the food plant species involved. Both the topological network metrics (complexity, nestedness, trophic niche redundancy) and robustness to climate change strongly increased in forest edges and fragments as opposed to the managed forest interior. The nature of the changes indicates that human impacts modify network structure mainly via host plant availability to insect herbivores. Improved robustness of PIHNs in forest edges/small fragments to climate-driven extinction cascades was attributable to an overall higher thermotolerance across plant communities, along with positive effects of network structure. The impoverishment of PIHNs in managed forest interiors and the suggested loss of insect diversity from climate-induced co-extinction highlight the need for further research efforts focusing on adequate silvicultural and conservation approaches.
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Quinteiro, Tamara, José Lopes i Ivan Carlos Fernandes Martins. "Diversidade de Carabidae (Coleoptera) Amostrados em Áreas de Reflorestamento de Mata Ciliar e Fragmento Florestal, no Estado do Paraná". EntomoBrasilis 5, nr 3 (12.12.2012): 217–22. http://dx.doi.org/10.12741/ebrasilis.v5i3.255.
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Carabidae são Coleoptera com a maioria de suas espécies apresentando hábito alimentar predatório. O objetivo do presente trabalho foi estudar a diversidade e abundância da família Carabidae (Coleoptera) em áreas de fragmento florestal e em áreas de reflorestamento de mata ciliar, evidenciando a importância deste grupo como indicador da biodiversidade em relação ao sucesso do reflorestamento. Os besouros foram amostrados por meio de armadilhas de solo pitfall, em fragmentos florestais e reflorestamentos de mata ciliar em três municípios do estado do Paraná. A abundância de Carabidae foi maior nos reflorestamentos de mata ciliar. A espécie Odontochila nodicornis (Dejean) foi, significativamente, a mais abundante e encontrada em todas as áreas estudadas. Houve similaridade da riqueza de carabídeos encontrada no fragmento florestal remanescente com a riqueza constatadas nos reflorestamentos, mesmo naqueles onde as coletas foram realizadas distante 3 Km do fragmento ou nas áreas de reflorestamento que não apresentavam conexão com o fragmento remanescente. Tetracha brasiliensis (Kirby) foi coletado quase que exclusivamente no reflorestamento sem conexão com o fragmento. Utilizando-se o teste de Kruskal-Wallis, não se constatou atratividade pelas diferentes iscas, no entanto verificou-se diferença significativa entre o número coletado nas armadilhas com iscas, quando comparado com o controle. A maior concentração de carabídeos coletados foi no período de dezembro a fevereiro, estação correspondente ao verão para a região estudada. A similaridade da riqueza de carabídeos encontrada entre os fragmentos de floresta e os reflorestamentos de mata ciliar, pode sugerir sucesso do método de reflorestamento, estando avançando para condições de característica primária.
Diversity of Carabidae (Coleoptera) Samples in Areas of Riparian Reforestation and Forest Fragment, in the State of Paraná
Abstract. Carabidae are Coleoptera whose most species have a predatory eating habit. The purpose of this paper was to study the diversity and abundance of Carabidae (Coleoptera) family in forest fragment areas and in reforestation areas of riparian vegetation, evidencing the importance of this group as a biodiversity indicator regarding the reforestation success. Beetles were sampled using soil pitfall traps in forest fragments and reforestation of riparian vegetation in three municipalities the state of Parana. The abundance of Carabidae was higher in riparian reforestation. The species Odontochila nodicornis (Dejean) was the most significantly abundant and found in all studied areas. There was a similarity in richness of Carabidae found in the remaining forest fragment, being the wealth found in reforestation, even where samples were collected 3km away from the fragment or in reforestation areas that did not have any connection with the remaining fragment. Tetracha brasiliensis (Kirby) was almost exclusively collected in reforestation unrelated to the fragment. Using the Kruskal-Wallis test, it was not noted any attraction of different baits, but there was a significant difference between the collection number in baited traps compared with the control. The highest concentration of Carabidae was collected from December to February, period corresponding to the summer season for the studied region. The similarity on the richness of Carabidae found between forest fragments and reforestation of riparian vegetation may suggest the reforestation method success, being able to advance to the primary characteristic.
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Secco, Helio, Clara Grilo i Alex Bager. "Habitat selection by the black-tufted marmoset Callithrix penicillata in human-disturbed landscapes". Journal of Tropical Ecology 34, nr 2 (marzec 2018): 135–44. http://dx.doi.org/10.1017/s026646741800007x.
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Abstract:There are several primate species with high risk of extinction in small forest fragments disturbed by human activities. However, some species exhibit high ecological plasticity, which allows them to persist in human-modified landscapes. The main goal of this study is to examine the relative roles of vegetation (mean distance among trees and mean canopy cover), human disturbance (distance to the road, distance to the fragment edge and edge type), and habitat spatial configuration (spatial autocorrelation index, category of quadrat – position within the fragment/fragment type) on the habitat selection of the black-tufted marmoset Callithrix penicillata in forest patches. We selected forest patches near and away from roads/urban areas, in southern Minas Gerais state, south-eastern Brazil. We used generalized linear mixed models to explain the presence of black-tufted marmoset in those patches. Our results show that black-tufted marmoset tend to occupy forest fragments closer to roads/urban areas, and consequently are under the influence of anthropic disturbance. In addition to the area delimited by these fragments, there is a preference for edge environments, where disturbances are exacerbated and the ecological conditions are suitable for exploitation by the black-tufted marmoset (supply of gum trees and reduced risk of competition). We suggest that a cross-habitat spillover by marmoset occur from forests to small habitat patches close to human-modified areas, such as those in proximity to roads and urban zones.
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Rodrigues, Diego Resende, Yves Rafael Bovolenta, José Antonio Pimenta i Edmilson Bianchini. "HEIGHT STRUCTURE AND SPATIAL PATTERN OF FIVE TROPICAL TREE SPECIES IN TWO SEASONAL SEMIDECIDUOUS FOREST FRAGMENTS WITH DIFFERENT CONSERVATION HISTORIES". Revista Árvore 40, nr 3 (czerwiec 2016): 395–405. http://dx.doi.org/10.1590/0100-67622016000300003.
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ABSTRACT Anthropogenic disturbances in forests modify survival conditions and development of plants, which has direct effect on the height and spatial structure of tree populations. This study aimed to compare the height structure and spatial pattern of five tree species in two distinct fragments of seasonal semideciduous forest with different histories of conservation. We studied shade-intolerant (Astronium graveolens Jacq., Gallesia integrifolia (Spreng.) Harms) and shade-tolerant species (Chrysophyllum gonocarpum (Mart. & Eichler ex Miq.) Engl., Euterpe edulis Mart. and Holocalyx balansae Micheli). Sixty plots of 100 m2 (10 m x 10 m) were allocated, being 30 contiguous plots in each fragment. All individuals of five species were marked, assessed for total height data and mapped using Cartesian coordinates. We observed differences in height structure between fragments. All populations had a random spatial pattern, except to H. balansae in the less conserved fragment and E. edulis in the conserved fragment that showed a clumped spatial pattern. There were evidences of forest regeneration due to the establishment of shade-tolerant species in less conserved fragment and coexistence of functional groups in both fragments. The height structure and spatial pattern analyses indicating that anthropogenic exploitation changed the environment and population structure in the less conserved area when compared to conserved area. The anthropic exploitation was ceased few years ago, so it is expected that the less conserved fragment reach the stability of an old-growth forest.
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Stein, Katharina, Christoph Rosche, Heidi Hirsch, Anke Kindermann, Julia Köhler i Isabell Hensen. "The influence of forest fragmentation on clonal diversity and genetic structure in Heliconia angusta, an endemic understorey herb of the Brazilian Atlantic rain forest". Journal of Tropical Ecology 30, nr 3 (24.02.2014): 199–208. http://dx.doi.org/10.1017/s0266467414000030.
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Abstract:Fragmented populations are usually exposed to the negative effects of reduced gene flow, genetic drift and population differentiation. These effects result in the collective loss of genetic variation, thereby reducing the probability of population adaptation to new environmental conditions and increasing the risk of extinction. Forest fragments commonly exhibit suboptimal site conditions, which can result in enhanced clonal reproduction, and a potential reduction in clonal diversity due to increased selfing and inbreeding depression. The clonal diversity, genetic diversity and structure of Heliconia angusta (Heliconiaceae) were assessed using AFLP-markers. We analysed six patches in the continuous forest (Atlantic rain forest, State of Rio de Janeiro) and eight patches (155 leaf samples in total) in five nearby forest fragments (age of oldest fragment: c. 50 y; size range: < 5–100 ha). Clonal diversity (Pd) of patches was slightly, yet significantly, lower in forest fragments compared with continuous forest. Measures of genetic diversity of patches in forest fragments did not differ from those in the continuous forest. A STRUCTURE analysis did not show any clear clustering of patches in the continuous forest and forest fragments. Our results suggest that H. angusta has not yet suffered from the anticipated negative effects of fragmentation.
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Weiskopf, Sarah R., Jennifer L. McCarthy, Kyle P. McCarthy, Alexey N. Shiklomanov, Hariyo T. Wibisono i Wulan Pusparini. "The conservation value of forest fragments in the increasingly agrarian landscape of Sumatra". Environmental Conservation 46, nr 4 (22.07.2019): 340–46. http://dx.doi.org/10.1017/s0376892919000195.
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SummaryDestruction of tropical rainforests reduces many unprotected habitats to small fragments of remnant forests within agricultural matrices. To date, these remnant forest fragments have been largely disregarded as wildlife habitat, and little is known about mammalian use of these areas in Sumatra. Here, we conducted camera trap surveys (2285 trap-nights) within Bukit Barisan Selatan National Park and five surrounding remnant forest fragments during 2010–2013 and used species composition metrics to compare use. We found 28 mammal species in the protected forest and 21 in the fragments. The fragments harboured a subset of species found in the protected forest and several species not observed in the protected forest. Critically endangered species such as Sunda pangolin (Manis javanica) and Sumatran tiger (Panthera tigris sumatrae) were found in the forest fragments, along with species of conservation concern such as marbled cat (Pardofelis marmorata) and Asiatic golden cat (Pardofelis temminckii). The biodiversity found within the fragments suggests that these small patches of remnant forest may have conservation value to certain mammal species and indicates the importance of further research into the role these habitats may play in landscape-level, multispecies conservation planning.