Gotowe bibliografie tematyczne / Exclosure

Gotowa bibliografia na temat „Exclosure”

Autor: Grafiati

Data publikacji: 4 czerwca 2021

Data aktualizacji: 4 lutego 2022

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Artykuły w czasopismach na temat "Exclosure"

Ibrahim, Temima, Fikrey Tesfay i Bethel Geremew. "Diversity of Woody Species and Biomass Carbon Stock in Response to Exclosure Age in Central Dry Lowlands of Ethiopia". Open Environmental Research Journal 14, nr 1 (20.04.2021): 1–12. http://dx.doi.org/10.2174/2590277602114010001.

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Objective: Empirical evidence on the potential of area exclosure in the restoration of severely degraded lands is crucially important. Thus, a study was conducted to examine the influence of exclosure age on vegetation structure, diversity, and biomass carbon stock in the central dry lowland of Ethiopia. Methods: Exclosures of 5, 15, >20 years old, and adjacent open grazing land were selected. Data on vegetation were collected using 20 × 20 m sampling quadrats which were laid along parallel transect lines. Results: The result showed that 17 woody species which represent 9 families were recorded at exclosures and open grazing lands. Shannon-Wiener (H') diversity index ranged from 0.74 (open grazing land) to 2.12 (middle age exclosure). Shannon evenness (E) index was higher in the middle age exclosure (0.80). Woody species basal area and tree density significantly (p < 0.05) increased with increasing exclosure age. The Aboveground woody biomass significantly (p < 0.05) varied from 12.60 (open grazing land) to 68.61 Mg ha-1 (middle age exclosure). Similarly, the aboveground biomass (AGB) carbon stocked was significantly (p < 0.05) higher in the middle (32 Mg ha-1) and old age exclosures (31 Mg ha-1). Conclusion: This study indicated that exclusion can restore the degraded vegetation and sequester and stock more atmospheric carbon dioxide in the aboveground biomass. Therefore, open degraded grazing land of the lowland areas can be restored into a promising stage through area exclosure land use management.

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Bastin, Gary, John Ludwig, Robert Eager, Adam Liedloff, Reginald Andison i Michael Cobiac. "Vegetation changes in a semiarid tropical savanna, northern Australia: 1973 - 2002". Rangeland Journal 25, nr 1 (2003): 3. http://dx.doi.org/10.1071/rj03001.

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We measured vegetation changes inside and outside two exclosures built in 1973 on red calcareous loam soils located in Conkerberry Paddock on Victoria River Research Station in northern Australia. These two exclosures were unburnt since their establishment in 1973 until exclosure 1 was unintentionally burnt late in the dry season (October) of 2001. Data from permanent transects and examples from photopoints illustrate that from mostly bare soils in 1973, total pasture biomass recovered relatively rapidly both inside and outside exclosures (in about five years). This initial recovery was primarily due to the establishment of annual grasses and forbs. After this five year period, there was a consistent increase in the biomass of perennial grasses, such as Heteropogon contortus and Dichanthium spp. Also in the first five years after exclosure, the exotic shrub, Calotropis procera,invaded the study area, but then largely disappeared in a period of lower wet-season rainfall in the late 1980s. The density of native tree species, particularly Hakea arborescens, Eucalyptus pruinosa and Lysiphyllum cunninghamii increased in general, but more so inside one or other of the exclosures. Although the late dry-season fire of 2001 reduced the density of larger H. arborescens and L. cunninghamii inside the exclosure at Site 1, this effect was not apparent for smaller trees and for trees outside this exclosure. Our findings show that savanna vegetation can change massively in the medium term (29 years) and that exclosure from cattle grazing can contribute to our understanding of the role of livestock in such change. However, exclosures by themselves do not provide adequate information about the processes leading to vegetation change replicated experimental studies are needed. That substantial increase in the biomass and proportion of perennial grasses occurred with light to moderate cattle grazing implies that these rangelands can be managed for production, although control of woody vegetation is an issue.

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Mekuria, Wolde. "Changes in Regulating Ecosystem Services following Establishing Exclosures on Communal Grazing Lands in Ethiopia: A Synthesis". Journal of Ecosystems 2013 (26.06.2013): 1–12. http://dx.doi.org/10.1155/2013/860736.

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In four separate studies undertaken in the northern highlands of Ethiopia, changes in regulating ecosystem services, economic viability, and the perception of local communities following establishing exclosures on communal grazing lands were investigated. Replicated 5-, 10-, 15-, and 20-year-old exclosures were selected and paired each exclosure with an adjacent grazing land. All exclosures displayed higher ecosystem services than communal grazing lands. Differences between exclosures and grazing lands varied between 29 (±4.9) and 61 (±6.7) Mg C ha−1 for ecosystem carbon stock (ECS), 2.4 (±0.6) and 6.9 (±1.8) Mg ha−1 for total soil N stock, and 17 (±3) to 39 (±7) Kg ha−1 for the available P stock, and all differences increased with exclosure duration. Differences in plant species richness and biomass between an exclosure age and communal grazing land were higher in oldest than in youngest exclosures. Over a period of 30 years, sequestered carbon dioxide was 246 Mg ha−1, total soil nitrogen increased by 7.9 Mg ha−1, and additional available phosphorous stocks amounted to 40 kg ha−1. The Net Present Value of exclosures ecosystem services under consideration was about 28% (837 US$) higher than alternative wheat production indicating that exclosures are competitive to alternative land uses. There are substantial opportunities to mobilize the local communities in efforts to establish exclosures, given that more than 75% had a positive view on exclosures effectiveness to restore degraded ecosystems. Establishing exclosures on communal grazing lands can be effective for restoring degraded ecosystems and the services that they provide.

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Kirkpatrick, J. B., i K. L. Bridle. "Comparative Effects of Stock and Wild Vertebrate Herbivore Grazing on Treeless Subalpine Vegetation, Eastern Central Plateau, Tasmania". Australian Journal of Botany 47, nr 6 (1999): 817. http://dx.doi.org/10.1071/bt98029.

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The existence of two 25-year-old grazing exclosures on Liawenee Moor, Eastern Central Plateau, Tasmania, created an opportunity to investigate the impacts of vertebrate herbivores on treeless subalpine vegetation. There were three treatments: sheep-, native herbivore- and rabbit-grazed; native herbivore- and rabbit-grazed; no grazing. The amount of bare ground was highest in the sheep-grazed plots, while vegetation cover was greatest in the ungrazed exclosure. The cover of all lifeform groups, except small herbs, was greater in the exclosures than in the sheep-grazed plots. The percentage frequency of tall herbs was significantly less in the sheep-grazed plots than either of the grazing exclosures. Tall herbs were more likely to be found under the canopy of other vegetation in the sheep-grazed plots while the same species were found to be growing in locations with no other vegetation cover in the ungrazed exclosure. Revegetation of bare ground averaged 1% per year over a 20-year period in the ungrazed exclosure. While percentage bare ground has also decreased in the native- and rabbit-grazed exclosure, it has increased in the sheep-grazed plots. Domestic stock grazing appears to have a much greater impact on vegetation cover, species composition and community structure than grazing by native herbivores and rabbits. No grazing allows for the fastest rehabilitation of the area. Our results are consistent with those from alpine and treeless subalpine areas of the Australian mainland.

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Bode, Michael, Karl E. C. Brennan, Keith Morris, Neil Burrows i Neville Hague. "Choosing cost-effective locations for conservation fences in the local landscape". Wildlife Research 39, nr 3 (2012): 192. http://dx.doi.org/10.1071/wr11106.

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Context Exclosure fences are widely used to reintroduce locally extinct animals. These fences function either as permanent landscape-scale areas free from most predators, or as small-scale temporary acclimatisation areas for newly translocated individuals to be ‘soft released’ into the wider landscape. Existing research can help managers identify the best design for their exclosure fence, but there are currently no methods available to help identify the optimal location for these exclosures in the local landscape (e.g. within a property). Aims We outline a flexible decision-support tool that can help managers choose the best location for a proposed exclosure fence. We applied this method to choose the site of a predator-exclusion fence within the proposed Lorna Glen (Matuwa) Conservation Park in the rangelands of central Western Australia. Methods The decision was subject to a set of economic, ecological and political constraints that were applied sequentially. The final exclosure fence location, chosen from among those sites that satisfied the constraints, optimised conservation outcomes by maximising the area enclosed. Key results From a prohibitively large set of potential exclosure locations, the series of constraints reduced the number of candidates down to 32. When ranked by the total area enclosed, one exclosure location was clearly superior. Conclusions By describing the decision-making process explicitly and quantitatively, and systematically considering each of the candidate solutions, our approach identifies an efficient exclosure fence location via a repeatable and transparent process. Implications The construction of an exclusion fence is an expensive management option, and therefore needs to convincingly demonstrate a high expected return-on-investment. A systematic approach for choosing the location of an exclosure fence provides managers with a decision that can be justified to funding sources and stakeholders.

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Otsu, Chiaki, Hayato Iijima i Takuo Nagaike. "Plant community recovery from intense deer grazing depends on reduction of graminoids and the time after exclosure installation in a semi-natural grassland". PeerJ 7 (1.10.2019): e7833. http://dx.doi.org/10.7717/peerj.7833.

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Exclosures that exclude large herbivores are effective tools for the protection and restoration of grazed plant communities. However, previous studies have shown that the installation of an exclosure does not ensure plant community recovery. Our study aimed to determine the effects of the domination of unpalatable plants and the timing of exclosure installation on the plant community recovery process in montane grassland overgrazed by sika deer (Cervus nippon) in Japan. In this study we compared plant species composition and their cover with inside and outside exclosures installed at different times. Furthermore, we also compared them with those in 1981, when density of sika deer was very low. We used quadrats inside and outside fenced areas established in 2010 and 2011 to record both the cover and the height of species in each quadrat between 2011 and 2015. Plant cover, with the exception of graminoid species, increased in later years in all treatments. Non-metric multidimensional scaling (NMDS) plots showed significantly differentiated treatment trends. The species composition within the 2010 fenced area gradually shifted to greater similarity with the species composition reported in 1981. The plant community in the 2011 fenced area was slower to recover. Compositions of plant communities outside the fenced areas hardly changed from 2011 to 2015. Chao’s dissimilarity index decreased over time between the plant community surveyed between 2011 and 2015 and the past plant community in 1981 within the exclosures, and was higher in the 2011 fenced area than in the 2010 fenced area. In conclusion, we show that the reduction of graminoids and the time after exclosure installation were important for plant community recovery from deer grazing damage. A delay in exclosure installation of one year could result in a delay in plant community recovery of more than one year.

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Gerke, Madlen, Daniel Cob Chaves, Marc Richter, Daniela Mewes, Jörg Schneider, Dirk Hübner i Carola Winkelmann. "Benthic grazing in a eutrophic river: cascading effects of zoobenthivorous fish mask direct effects of herbivorous fish". PeerJ 6 (14.02.2018): e4381. http://dx.doi.org/10.7717/peerj.4381.

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Benthic grazing strongly controls periphyton biomass. The question therefore arises whether benthic grazing could be used as a tool to reduce excessive growth of periphyton in nutrient-enriched rivers. Although benthic invertebrate grazers reduce the growth of periphyton, this is highly context dependent. Here we assessed whether the only obligate herbivorous fish in European rivers, the common nase (Chondrostoma nasus L.), is able to reduce periphyton biomass in a eutrophic river. We conducted three consecutive in situ experiments at low, intermediate and high densities of nase in the river using standard tiles on the river bottom naturally covered with periphyton that were accessible to fish and tiles that excluded fish foraging with electric exclosures. The biomass of benthic invertebrate grazers was very low relative to nase. We hypothesised that nase would reduce periphyton biomass on accessible tiles and therefore expected higher periphyton biomass on the exclosure tiles, at least at intermediate and high densities of nase in the river. Contrary to our expectation, the impact of fish grazing was low even at high fish density, as judged by the significantly lower chlorophyll a concentration on exclosure tiles even though the ash-free dry mass on accessible and exclosure tiles did not differ. The lower chlorophyll a concentrations on exclosure tiles might be explained by a higher biomass of invertebrate grazers on the exclosure tiles, which would indicate that the effect of invertebrate grazers was stronger than that of herbivorous fish grazers. The high biomass of invertebrate grazers on exclosure tiles likely arose from the exclusion of zoobenthivorous fish, which occur in the river at high densities. The results of our small-scale experiments suggested that cascading top-down effects of zoobenthivorous fish have a higher impact on periphyton biomass than direct effects of herbivorous nase.

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Abendroth, Emily. "Exclosure ]12[". WSQ: Women's Studies Quarterly 41, nr 3-4 (2013): 151–53. http://dx.doi.org/10.1353/wsq.2013.0096.

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Christianini, AV, i M. Galetti. "Toward reliable estimates of seed removal by small mammals and birds in the Neotropics". Brazilian Journal of Biology 67, nr 2 (maj 2007): 203–8. http://dx.doi.org/10.1590/s1519-69842007000200004.

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Birds are often considered seed predators of less importance when compared to rodents or granivorous ants in studies of seed predation using selective exclosures. However, it is possible that the role of granivorous birds interacting with seeds on the floor of Neotropical forests is being underestimated, if the selective exclosures designed to allow exclusive access to small rodents do not work properly in the Neotropics. We used an experimental approach to evaluate whether birds could remove seeds from selective exclosures designed to allow exclusive access to rodents. We compared seed removal from two paired treatments in the field: an open treatment (control) allowing the access to all vertebrates, and a selective exclosure treatment, where seeds were placed under a cage staked to the ground and covered on top and on the laterals by wire mesh of varying sizes. Treatments were placed in the center of a sand quadrat in order to record the visit of vertebrates from their footprints. Although the selective exclosures are used to tell apart the small mammal seed removal from that of other animals, birds could persistently remove seeds from selective exclosures. Thus, the role of birds interacting with seeds on the floor of tropical forests may be underestimated for some plant species, due to an artifact of the exclosure method employed. Exclosures of 40 x 40 x 40 cm should be efficient to deter the removal of seeds by birds, allowing the consumption of the seeds by small mammals at the same time.

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Courchesne, Milène, Stéphanie Pellerin, Marianne Bachand, Steeve D. Côté i Monique Poulin. "Chronic deer browsing leads to biotic homogenization of minerotrophic peatlands". Botany 96, nr 8 (sierpień 2018): 499–509. http://dx.doi.org/10.1139/cjb-2017-0145.

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Peatlands could become important foraging habitats, and their plant communities threatened, in areas with an overabundance of large herbivores. Peatland response to herbivore exclusion may vary widely according to abiotic conditions and associated species because of a strong minerotrophic gradient. We assessed the impact of white-tailed deer (Odocoileus virginianus Zimm.) on peatland vegetation using an exclosure experiment. A total of 53 pairs of exclosures and unprotected plots were set up in bogs (13 pairs), sedge fens (20), shrub fens (7), and laggs (13), and surveyed prior to exclosure construction as well as three, five, and eight years after. Vascular plant composition of exclosures diverged from that of unprotected plots through time only in shrub fens and laggs. Bryophytes remained constant in all habitats. On average, shrub cover was 30% higher in exclosures in all habitats after five years, whereas herb cover increased only in laggs, by 43%, after eight years. Reclassification of sites by pH showed deer exclusion promoted alpha diversity in low- and high-moderate rich fens (pH 5.3–6.8) and beta diversity in the latter as well as in rich fens (pH 6.3–7.5). Overall, our results suggest that conservation efforts in areas with overabundant large herbivores should target richer peatland habitats since they showed a higher resilience and fostered alpha and beta diversity.

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Rozprawy doktorskie na temat "Exclosure"

Ter, Beest Julia M. "EFFECTS OF A RESTORED ELK POPULATION ON SOILS, VEGETATION, AND WATER QUALITY IN EASTERN KENTUCKY". UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_theses/284.

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A restored elk (Cervus elaphus) population in eastern Kentucky may be affecting ecosystem processes in a landscape composed of reclaimed grassland expanses and isolated forest remnants. Elk routinely select forested ridge-tops as resting and ruminating sites. These locations are characterized by sparse or absent leaf litter, trampled and diminished vegetation, large deposits of dung, and urine-saturated soils. In fall 2003, a series of fenced ungulate exclosures were constructed; 8 on highly disturbed forested ridge-tops and 8 on reclaimed grasslands. Soil analyses measured % moisture, pH, total nitrogen, total carbon, ammonium, nitrate, phosphorus, and major extractable cations in 0-10 cm and 10-20 cm cores. Litter depths and percentages of bare ground, vegetative cover, litter cover, and woody debris were measured. Sediment and water samples were collected monthly from sediment traps on reference and experimental ridge-tops. Studentfs t-tests were used to determine significance (p . 0.10) between treatments. Disturbed ridge-tops had higher soil ammonium (0.68 mg/kg, 10-20 cm) than reference sites (0.25 mg/kg) in spring 2004 and lower ammonium (0.72 mg/kg, 0-10 cm; 0.44 mg/kg, 10-20 cm) than reference sites (1.80 mg/kg, 0-10 cm; 0.94 mg/kg, 10-20 cm) in summer 2004. Total carbon was higher inside (67.57 g/kg, 0-10 cm) than outside (45.38 g/kg) of ridge-top exclosures in fall 2004. Soil moisture, litter depths, and vegetative cover were generally lower, while % bare ground was higher on disturbed ridge-tops. Sediment collected from traps averaged 2.21g/m2 inside exclosures, 2.86 g/m2 outside exclosures, and 0.39 g/m2 on reference ridge-tops. These data suggest that this reintroduced species is changing several attributes of the Cumberland Plateau landscape. The lack of a predator such as the gray wolf (Canis lupis) or cougar (Puma concolor) likely contributes to the development of habitual elk use of landscape features such as remnant ridge-top forests. Such concentrated use may create conditions for the colonization of certain plant species including rare natives and invasive exotics. Continued monitoring of high use areas is recommended so that managers can fully understand the long-term impact of the return of this large, gregarious herbivore, and that appropriate management actions can be developed to promote native biodiversity.

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Adkins, Nicholas. "Vegetation Assessment to Understand the Effect of Feral Goat Populations on Native Flora Composition". Thesis, University of Canterbury. School of Forestry, 2012. http://hdl.handle.net/10092/7466.

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A vegetation assessment was conducted to understand the effect of feral goats (Capra hircus) on the vegetation of Isolated Hill Scenic Reserve located in Southern Marlborough. New Zealand forests evolved without the pressure of mammalian herbivores but following human settlement they became subject to intensive browsing following the introduction of exotic mammals. This study focuses on the presence of feral goats. Interest arises from the settlement of other countries and the subsequent liberations of feral goats which are now considered to be responsible for the significant removal of native vegetation as well as playing a dominant role in erosion. Changes in plant communities have occurred with the pressure of goat browsing as well as secondary effects such as habitat degradation The purpose of this research was to investigate the changes in plant species composition since the initial and subsequent research conducted in 1985 and 1994. An analysis of previous work on the diet of multiple introduced ungulate species was also conducted. Previous studies were not limited to only feral goat studies and included other introduced herbivores to provide a broad overview of diets. The New Zealand Forest Service implemented a programme for monitoring the seral forest in Isolated Hill Scenic Reserve using standard Forest Service vegetation quadrants. 32 quadrants were established, including three exclosures, in various locations around the Reserve to allow assessment of feral goat impacts on seral forests (forest whose constituents are of varied age classes). Nine forest service plots, including three exclosures were re-measured and an additional nine plots were measured. Given the progression of vegetation change that has been observed during the course of this study, both analytically and observationally, Isolated Hill Scenic Reserve in its current state, involving the notable presence of feral goats and the vegetation types will continue to diminish in diversity.

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Leeson, Ryan Elizabeth. "Interactions between white-tailed deer and vegetation in southern Illinois". OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2314.

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White-tailed deer (Odocoileus virginianus) have considerable impacts on woody and herbaceous vegetation. Many oak-hickory forests in the eastern U.S. are experiencing a lack of oak (Quercus) and hickory (Carya) regeneration, with deer being a likely culprit. Furthermore, few have studied deer use of different herbaceous food plot mixtures. I addressed these gaps in the literature by assessing deer impacts on forest and herbaceous vegetation in southern Illinois. I established 150 paired plots (enclosed and control) in June 2015 and measured 25 habitat variables to assess impacts of deer herbivory from August 2015 to August 2016. Oak seedlings were present more often and in higher numbers within enclosed plots (F1,299 = 6.25, P < 0.050 and F1,387 = 4.50, P < 0.050, respectively). There were no differences in the height of oak seedlings or the presence, number, or height of hickory seedlings in enclosed versus control plots (F1,53 = 0.010, P = 0.938; F1,299 = 0.850, P = 0.357; F1,267 = 1.16, P = 0.282; and F1,15 = 0.030, P = 0.855; respectively). During September-November 2015, I counted and marked fallen acorns within 50 random paired plots; the number of acorns discovered or lost did not differ between enclosed and control plots (F1,94 = 0.310, P = 0.578 and F1,8 = 0.120, P = 0.736, respectively). I suggest managers incorporate potential deer impacts when designing management plans to best encourage oak regeneration. During September-November 2015, I established 16 food plots (half tilled; each 0.05 ha in size), planted to 4 food plot types. I compared Big Tine Buck Brunch, Evolved Harvest Throw & Gro, Antler King No Sweat, and a food plot mixture that I created. I measured deer use via 2 methods: vegetation growth in exclosures versus control (i.e., unfenced) areas and camera traps. Deer used all 4 food plot mixtures (n = 292 – 2,522 pictures/plot over 9 weeks), having a negative impact on mean vegetation height outside of exclosures (F3,1148 = 6.71, P < 0.001). Analysis of camera data indicated that deer did not preferentially use any one food plot mixture over the others (F3,12 = 0.090, P > 0.050). There also was no difference in the proportion of deer pictured in the process of eating within each food plot mixture (F3,12 = 0.592, P > 0.050). I suggest any of these 4 food plot varieties could be planted by a hunter or wildlife manager in the Midwest and observe similar use by deer.

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au, k. maher@murdoch edu, i Kellie Maher. "Encroachment of sandplain heathland (kwongan) by Allocasuarina huegeliana in the Western Australian wheatbelt: the role of herbivores, fire and other factors". Murdoch University, 2008. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20081211.92011.

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Kwongan, also known as sandplain heathland, occurs in remnant vegetation throughout the fragmented landscape of the Western Australian wheatbelt. This vegetation community has high levels of species richness and endemism, and is of high conservation value. In many vegetation remnants in the wheatbelt the native tree species Allocasuarina huegeliana (rock sheoak) is expanding out from its normal range and encroaching into kwongan. A. huegeliana may ultimately dominate the kwongan, causing a decline in floristic diversity. Altered disturbance regimes, particularly the absence of fire and reduced or absent browsing mammal herbivores, are likely to be responsible for causing A. huegeliana encroachment. This study used experimental and observational data from patches of kwongan in three Nature Reserves in the central and southern wheatbelt to investigate the role of fire, native mammal activities and interactions between these two factors in shaping A. huegeliana woodlandkwongan community boundaries. Investigations were carried out into the characteristics of encroaching A. huegeliana populations; the environmental factors affecting the extent of encroachment, naturally recruited juveniles, and seedling emergence and establishment; historical and current abundances of native mammals; and the effects of mammal herbivores on seedling establishment during inter-fire and post-fire periods. Results from this study confirm that A. huegeliana has encroached into kwongan throughout the wheatbelt region and recruitment appears likely to continue in most areas. Few of the environmental factors measured in this study affected the extent of encroachment, the locations of naturally recruited A. huegeliana juveniles, and seedling germination and establishment. Western grey kangaroos (Macropus fuliginosus) browsed extensively on seedlings, which largely prevented them from establishing in open areas of kwongan. However, numerous A. huegeliana seedlings escaped browsing herbivores by establishing in perennial shrubs, where they appeared to be tolerant of increased levels of inter-specific competition. There was no native mammal common to all three Reserves that declined around the time that A. huegeliana encroachment most likely began in the 1970s. In addition, tammar wallabies (Macropus eugenii) had little effect even where their densities were high. It is therefore unlikely that the decline of an individual mammal species initiated encroachment. A. huegeliana encroachment appears to be driven by increased propagule pressure, which is in turn caused by increased inter-fire intervals. Long periods of time without fire have enabled fire-sensitive A. huegeliana trees to produce increasing quantities of seed that are continuously released into kwongan. A range of other factors may interact synergistically with this process to affect encroachment and these are also discussed. This study considered the implications of these findings for management of remnant vegetation in fragmented landscapes, particularly kwongan in the Western Australian wheatbelt, and areas for further research are suggested.

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Lemessa, Debissa. "Pests and pest controlling organisms across tropical agroecological landscapes in relation to forest and tree-cover". Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-102849.

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A major challenge in agroecosystems is how to manage the systems so that it reduces crop pests and enhances natural pest control. This thesis investigates patterns of crop pests and top-down effects of birds and arthropod predators in relation to land-use composition across spatial scales. In paper (I) I examined the crop distribution and land-use types in relation to the crop raiding patterns in 15 transectsin sites close to and far from forests along with a questionnaire survey at household level. I found severe crop raiding close to forests, but it had no impact on crop composition growing between the two sites. In paper (II) I examined the effect of forest and tree cover, at local and landscape scales, on the abundance of arthropod predators by collecting specimens from 40 home gardens. My result showed higher abundance of arthropod predators when either the home garden or the surroundings had a high tree-cover, compared to when tree-cover at both scales was similarly either high or low. In paper (III) I investigated the effect of excluding birds and arthropod predators on leaf damage on rape seed in 26 home gardens. I found stronger top-down impacts from arthropod predators on crop pests in tree-poor gardens than in tree-rich gardens. There was no effect of birds. In paper (IV) I explored the effect of landscape complexity on bird and arthropod predation using plasticine caterpillars in 36 home gardens across landscapes. The rate of arthropod predation on caterpillars was higher in simple than in complex landscapes. The rate of bird predation did not vary between complex and simple landscapes. In simple landscapes, arthropod predation was higher than that of birds. The overall results suggest that simplified gardens/landscapes still have enough habitat heterogeneity to support arthropod predators for the significant top-down controlling effect on crop pests. However, I did not find clear effect of complexityon the top-down effect of birds.

At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 1: Manuscript; Paper 3: Manuscript; Paper 4: Manuscript

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Burkholder, Derek A. "Top Down Control in a Relatively Pristine Seagrass Ecosystem". FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/799.

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The loss of large-bodied herbivores and/or top predators has been associated with large-scale changes in terrestrial, freshwater, and marine ecosystems around the world. Understanding the consequences of these declines has been hampered by a lack of studies in relatively pristine systems. To fill this gap, I investigated the dynamics of the relatively pristine seagrass ecosystem of Shark Bay, Australia. I began by examining the seagrass species distributions, stoichiometry, and patterns of nutrient limitation across the whole of Shark Bay. Large areas were N-limited, P-limited, or limited by factors other than nutrients. Phosphorus-limitation was centered in areas of restricted water exchange with the ocean. Nutrient content of seagrasses varied seasonally, but the strength of seasonal responses were species-specific. Using a cafeteria-style experiment, I found that fast-growing seagrass species, which had higher nutrient content experienced higher rates of herbivory than slow-growing species that are dominant in the bay but have low nutrient content. Although removal rates correlated well with nutrient content at a broad scale, within fast-growing species removal rates were not closely tied to N or P content. Using a combination of stable isotope analysis and animal borne video, I found that green turtles (Chelonia mydas) – one of the most abundant large-bodied herbivores in Shark Bay – appear to assimilate little energy from seagrasses at the population level. There was, however, evidence of individual specialization in turtle diets with some individuals foraging largely on seagrasses and others feeding primarily on macroalgae and gelatinous macroplankton. Finally, I used exclusion cages, to examine whether predation-sensitive habitat shifts by megagrazers (green turtles, dugongs) transmitted a behavior-mediated trophic cascade (BMTC) between sharks and seagrasses. In general, data were consistent with predictions of a behavior-mediated trophic cascade. Megaherbivore impacts on seagrasses were large only in the microhabitat where megaherbivores congregate to reduce predation risk. My study highlights the importance of large herbivores in structuring seagrass communities and, more generally, suggests that roving top predators likely are important in structuring communities - and possibly ecosystems - through non-consumptive pathways.

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Grubh, Archis R. "Effects of anthropogenic disturbances and biotic interactions on stream biota in gulf coastal plain streams". The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1155753270.

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Brandenburg, Marci D. "Effects of deer exclosures on forest floor mammals". Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1097606609.

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Brandenburg, Marci. "Effects of deer exclosures on forest floor mammals". Ohio University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1097606609.

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Bunn, Victoria Jeanne. "The effects of riparian grazing exclosures on adjacent riverine ecosystems". Thesis, Montana State University, 2011. http://etd.lib.montana.edu/etd/2011/bunn/BunnV0811.pdf.

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In the western U.S., riparian ecosystems cover 1% of land area while supporting 70-80% of native species. 70% of this land area is available as range for livestock, who use riparian areas preferentially. Ecological concerns have led to numerous studies of the effects grazing has on these ecologically important, easily damaged ecosystems. Exclosure-based research has thoroughly examined the effects of livestock on riparian ecosystem health and function, but failed to investigate the potential for exclosures to intensify adverse effects of use at their boundaries, which could lead to overestimation of their benefits and impair their efficacy in management. This study attempts to supplement existing research by characterizing potential impacts, making exclosures a more informed and effective management strategy. Study exclosures were located on grazed public lands in southwest Montana. Riparian vegetative cover and channel morphology response variables were measured inside the exclosure and in two grazed reaches, one placed 0 to 20 m and one >50 m from the exclosure to capture differences in the spatial extent and severity of any impacts due to differences in livestock behavior caused by the exclosure's influence. Findings were that (1) results were consistent with previous exclosure studies using the same response variables to compare grazed and exclosed areas, (2) significant differences in herbaceous cover, bare ground cover, channel width, and bank angle between the two grazed subreaches were greater than corresponding grazed/exclosed comparisons, indicating that impacts to the subreach adjacent to the exclosure that are greater than corresponding improvements within, (3) spatially inconsistent impact zones within and among sites made it impossible to describe an overall impact zone adjacent to exclosures, but impacts to channel morphology, herbaceous cover, and bare ground occurred within 8 m of the exclosure, and within 2 m for bank angle, (4) data didn't support predicted relationships between impact severity and exclosure duration, size, or stocking rates, most likely due to the many other influencing factors that were not measured. Evidence supporting existence of exclosure-caused impacts should inform exclosure use and make it a more effective management tool, especially when considered in the context of how these impacts might encumber specific management goals.

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Książki na temat "Exclosure"

Roe, Lisa Schassberger. Establishment report for exclosure studies of Arabis fecunda. Helena, Mont: Montana Natural Heritage Program, 1992.

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McCullough, Dale A. Monitoring of streambank stability and streamside vegetation in a livestock exclosure on the Warm Springs River, Oregon: Comparison of ground-based surveys with aerial photographic analysis. Portland, Or: Columbia River Inter-Tribal Fish Commission, 1999.

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Johnson, Charles G. Rangeland exclosures of northeastern Oregon: Stories they tell (1936-2004). Portland, OR: U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station, 2007.

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Bartos, Dale L. Pine Hollow exclosures: Effect of browsing on an Aspen community sprayed with 2,4-D. Ogden, Utah] (324 25th St., Ogden 84401): U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station, 1990.

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Bartos, Dale L. Pine Hollow exclosures: Effect of browsing on an Aspen community sprayed with 2,4-D. [Ogden, Utah (324 25th St., Ogden 84401)]: U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station, 1990.

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Exclosures. Ahsahta Press, 2014.

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Impact of cattle on Department of Conservation grazing leases in South Westland: Results from monitoring 1989-99, and recommendations. Wellington, N.Z: Dept. of Conservation, 2001.

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Engley, Lance. Use of Predator Exclosures to Protect Piping Plover Nests in Alberta, 1998-2001. Alberta Conservation Association, 2005.

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Części książek na temat "Exclosure"

Shimelse, Samson, Tamrat Bekele i Sileshi Nemomissa. "Area Exclosure as a Strategy for Climate Change Mitigation: Case Study from Tigray Region, Northern Ethiopia". W Handbook of Climate Change Resilience, 403–28. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-93336-8_123.

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Shimelse, Samson, Tamrat Bekele i Sileshi Nemomissa. "Area Exclosure as a Strategy for Climate Change Mitigation: Case Study from Tigray Region, Northern Ethiopia". W Handbook of Climate Change Resilience, 1–26. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-71025-9_123-1.

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Mekuria, Wolde, Edzo Veldkamp, Marife D. Corre i Mitiku Haile. "Carbon Changes Following the Establishment of Exclosure on Communal Grazing Lands in the Semi-Arid Lowlands of Tigray, Ethiopia". W Climate Change Management, 111–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-22315-0_7.

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Ptatscheck, Christoph. "Role of nematodes in the food web: nematodes as predator and prey." W Ecology of freshwater nematodes, 216–46. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0007.

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Abstract This chapter provides information on the role of nematodes in the food web, including their participation in matter and energy fluxes within ecosystems. It highlights that nematodes are both predators and prey for organisms ranging from protozoans to vertebrates, based on gut analyses and direct observations. Functional response experiments, microcosm studies, and enclosures/exclosures in the field can be used to investigate the intensity of these trophic interactions and their impact on individual species as well as entire communities.

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Jacob, Miro, Sil Lanckriet i Katrien Descheemaeker. "Exclosures as Primary Option for Reforestation in Dogu’a Tembien". W Geo-trekking in Ethiopia’s Tropical Mountains, 251–59. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-04955-3_16.

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"Paternity Exclosure". W Encyclopedia of Genetics, Genomics, Proteomics and Informatics, 1453. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6754-9_12392.

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Bond, William J. "Vertebrate herbivory and open ecosystems". W Open Ecosystems, 121–40. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198812456.003.0008.

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Can herbivores account for the widespread occurrence of open ecosystems? Some suggest that Pleistocene megafauna did so, and large mammal herbivory is still important in some regions today. Exclosure studies have been widely used to test herbivore impacts on trees, but global patterns of the ‘brown world’ are not readily seen from satellites. Areas of mammal consumer dominance occur in cool temperate/boreal regions (e.g. Tibetan montane grasslands) and savannas in Africa, but not in those in Australia or South America. Herbivores vary in their impact on openness of vegetation because of differences in body size, feeding mode, predator avoidance behaviour while plants also differ in their defences and accessibility. Unlike fire, proxies are lacking for how extinct herbivores, even giant sauropods, impacted vegetation. Very few studies deal explicitly with how vertebrate herbivores help create and maintain open ecosystems where climates are suitable for forests, and there is an urgent need to find out more.

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Streszczenia konferencji na temat "Exclosure"

Westin, Emelie. "Regeneration of deciduous trees – Variable success of moose exclosures in central Sweden". W 5th European Congress of Conservation Biology. Jyväskylä: Jyvaskyla University Open Science Centre, 2018. http://dx.doi.org/10.17011/conference/eccb2018/107942.

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"Soil Organic Carbon and Nutrient Contents are not Influenced by Exclosures Established in Communal Grazing Land in Nile Basin, Northern Ethiopia". W International Conference on Advances in Agricultural, Biological & Environmental Sciences. International Institute of Chemical, Biological & Environmental Engineering, 2014. http://dx.doi.org/10.15242/iicbe.c1014045.

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Raporty organizacyjne na temat "Exclosure"

Kuck, Todd. Grande Ronde Model Watershed Project; Dark Canyon Riparian Exclosure, Completion Report 2002. Office of Scientific and Technical Information (OSTI), marzec 2003. http://dx.doi.org/10.2172/963057.

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Epiphan, Jean, i Steven Handel. Assessment of vegetation in six long-term deer exclosure investigations at Morristown National Historical Park: Data synthesis & management recommendations. National Park Service, październik 2020. http://dx.doi.org/10.36967/nrr-2279121.

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Ehrenfield, Joan G., Kristen A. Ross, Manisha Patel, Jean N. Epiphan i Steven N. Handel. Recovery of native plant species after initial management of non-native plant invaders: Vegetation monitoring in an exclosure in Morristown National Historical Park. National Park Service, sierpień 2020. http://dx.doi.org/10.36967/nrr-2278124.

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Johnson, Charles Grier. Rangeland exclosures of northeastern Oregon: stories they tell (1936–2004). Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, 2007. http://dx.doi.org/10.2737/pnw-gtr-724.

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Mekuria, W., G. Gebregziabher i N. Lefore. Exclosures for landscape restoration in Ethiopia: business model scenarios and suitability. International Water Management Institute (IWMI), 2020. http://dx.doi.org/10.5337/2020.201.

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Bartos, Dale L., i Roy O. Harniss. Pine hollow exclosures: Effect of browsing on an aspen community sprayed with 2,4-D. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, 1990. http://dx.doi.org/10.2737/int-rn-393.

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Kauffman, J. Boone. Research/Evaluate Restoration of NE Oregon Streams: Effects of Livestock Exclosures (Corridor Fencing) on Riparian Vegetation, Stream Geomorphic Features and Fish Populations; Final Report 2002. Office of Scientific and Technical Information (OSTI), wrzesień 2002. http://dx.doi.org/10.2172/812705.

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