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Ohsawa, M., P. H. J. Nainggolan, N. Tanaka et C. Anwar. « Altitudinal zonation of forest vegetation on Mount Kerinci, Sumatra : with comparisons to zonation in the temperate region of east Asia ». Journal of Tropical Ecology 1, no 3 (août 1985) : 193–216. http://dx.doi.org/10.1017/s0266467400000286.
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ABSTRACTThe altitudinal zonation of forests on Mount Kerinci, Sumatra (3800 m) is described and compared with that in the temperate region of east Asia. Nine plots were selected between 1750 m in altitude and the upper limit of vegetation at 3250 m, at intervals of about 200 m in altitude. The plots are distinguished according to their main dominants, and the population structure of the dominant species is examined. The lower forests have species showing the whole range of size classes as well as solitary giants as dominants, but the upper forests lack these giants and are floristically poorer. Between 1750 m (the start of well preserved natural vegetation) and 2950 m (the forest limit) three forest zones are distinguished, and between 2950 and 3250 m a scrub zone. Upper forest zones tend to be dominated by species of the same genus or family which form important understory components of the zone below. Based on floristic comparisons with mountains of higher latitudes (i.e. Himalayas and Japan), the two lower forest zones (up to 2400 m) represent a subtropical zone, and the upper forest zone a warm-temperate zone. Climatic conditions at the forest limit on Mount Kerinci are similar to those at the latitudinal limit of warm-temperate evergreen trees; in the Himalayas the forest limit represents the latitudinal limit of the cool-temperate, and in Japan of the subarctic Altitudinal zonation patterns change with latitude, reaching their most complex on subtropical mountains where the two floristic realms, the Boreal and Palaeotropical, meet. A scheme for the pattern of vegetation zonation in east Asia is proposed.
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Wang, Jing, Baiping Zhang et Yonghui Yao. « The Spatial Pattern of the Upper Limit of Montane Deciduous Broad-Leaved Forests and Its Geographical Interpretation in the East Monsoon Realm of China ». Forests 12, no 9 (9 septembre 2021) : 1225. http://dx.doi.org/10.3390/f12091225.
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Montane deciduous broad-leaved forests (MDB) are mainly distributed in the east monsoon realm of China. The upper limit of MDB significantly varies from mountain to mountain. However, the spatial pattern of the upper limit of MDB and its underlying drivers are still unknown. In this study, we conducted hierarchical multiple regression to quantify the effect of climatic factors, peak elevation, and cold tolerance of dominant species on the geographical distribution of the upper limit of MDB on 75 mountains in the east monsoon realm of China. The results show that: (1) the upper limit of MDB in the east monsoon realm of China, 2800 m, is the highest in Taibai peak of the Qinling mountain ranges, from where it tends to decrease both northward and southward. (2) The upper limit of MDB on the mountains with climatic treeline is mainly affected by climatic factors, the minimum temperature of the coldest month (MinT), and the precipitation seasonality (PS), with an R2 of 0.733. (3) The upper limit of MDB on both temperate and subtropical mountains without climatic treeline is affected by MinT, PS, peak elevation, and cold tolerance of dominant species together, with an R2 of 0.793 and 0.748, respectively. (4) The dominant species of the upper limit of MDB significantly differ temperate and subtropical ranges, the former of which is mainly in the genus Betula, and the latter of which is in the genus Quercus. The upper limit of MDB with the genus Fagus as dominant species is only distributed in the mountains towards the south of the Qinling mountain ranges. (5) The warmth index (WI) at the upper limit of deciduous broad-leaved forest on the mountains with climatic treeline is about 60 °C month, which is lower than that at the northernmost boundary of the latitudinal distributed deciduous broad-leaved forest (90 °C month). Our study revealed the spatial pattern and geographical drivers of the upper limit of MDB, improved our understanding of differences in MDB vegetation among different mountain ranges, and provided climatic correlates for predicting the dynamics of the upper limit of MDB under climate change.
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Kenney, W. A. « Leaf Area Density as an urban forestry planning and management tool ». Forestry Chronicle 76, no 2 (1 avril 2000) : 235–39. http://dx.doi.org/10.5558/tfc76235-2.
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Many of the benefits that we derive from urban forests are directly or indirectly related to the leaf area of the forest. If we are to consider these multiple benefits at the level of the forest, the use of Leaf Area Density (LAD) provides some advantages over other often used measures. Since many factors in the urban landscape can limit leaf area, Potential Leaf Area Density (PLAD) can provide a measure of the upper limit to leaf area density. Using these two measures, urban forest planners and managers can integrate many of the issues associated with broader aspects of the structure and benefits of the forest under their jurisdiction. Some planning, policy, and educational applications of LAD and PLAD are discussed. Key words: urban forestry management and planning, leaf area density
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Klinge, M., J. Böhner et S. Erasmi. « Modeling forest lines and forest distribution patterns with remote-sensing data in a mountainous region of semiarid central Asia ». Biogeosciences 12, no 10 (20 mai 2015) : 2893–905. http://dx.doi.org/10.5194/bg-12-2893-2015.
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Abstract. Satellite images and digital elevation models provide an excellent database to analyze forest distribution patterns and forest limits in the mountain regions of semiarid central Asia on the regional scale. For the investigation area in the northern Tien Shan, a strong relationship between forest distribution and climate conditions could be found. Additionally areas of potential human impact on forested areas are identified at lower elevations near the edge of the mountains based on an analysis of the differences in climatic preconditions and the present occurrence of forest stands. The distribution of spruce (Picea schrenkiana) forests is hydrologically limited by a minimum annual precipitation of 250 mm and thermally by a minimum monthly mean temperature of 5 °C during the growing season. While the actual lower forest limit increases from 1600 m a.s.l. (above sea level) in the northwest to 2600 m a.s.l. in the southeast, the upper forest limit rises in the same direction from 1800 m a.s.l. to 2900 m a.s.l.. In accordance with the main wind directions, the steepest gradient of both forest lines and the greatest local vertical extent of the forest belt of 500 to 600 m to a maximum of 900 m occur at the northern and western mountain fronts. The forests in the investigation area are strongly restricted to north-facing slopes, which is a common feature in semiarid central Asia. Based on the presumption that variations in local climate conditions are a function of topography, the potential forest extent was analyzed with regard to the parameters slope, aspect, solar radiation input and elevation. All four parameters showed a strong relationship to forest distribution, yielding a total potential forest area that is 3.5 times larger than the present forest remains of 502 km2.
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Klinge, M., J. Böhner et S. Erasmi. « Modelling forest lines and forest distribution patterns with remote sensing data in a mountainous region of semi-arid Central Asia ». Biogeosciences Discussions 11, no 10 (13 octobre 2014) : 14667–98. http://dx.doi.org/10.5194/bgd-11-14667-2014.
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Abstract. Satellite images and digital elevation models provide an excellent database to analyse forest distribution patterns and forest limits in the mountain regions of semi-arid Central Asia at the regional scale. For the investigation area in the northern Tien Shan a strong relation between forest distribution and climate conditions could be found. Additionally areas of potential human impact on forested areas are identified at lower elevations near the mountain border based on an analysis of the differences of climatic preconditions and present occurrence of forest stands. The distribution of spruce (Picea schrenkiana) forests is hydrologically limited by a minimum annual precipitation of 250 mm and thermally by a minimum monthly mean temperature of 5 °C during the growing season. While the actual lower forest limit increases from 1600 m a.s.l. in the northwest to 2600 m a.s.l. in the southeast, the upper forest limit takes the same course from 1800 to 2900 m a.s.l. In accordance with the main wind directions, the steepest gradient of both forest lines and the greatest local vertical extent of the forest belt of 500 to 600 m and maximum 900 m occur at the northern and western mountain fronts. The forests in the investigation area are strongly restricted to north facing-slopes, which is a common feature in semi-arid Central Asia. Based on the presumption that variations in local climate conditions are a function of topography, the potential forest extent was analysed with regard to the parameters slope, aspect, solar radiation input and elevation. All four parameters showed a strong relationship to forest distribution, yielding a total potential forest area that is 3.5 times larger than the present forest remains of 502 km2.
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Minďaš, Jozef, et Jana Škvareninová. « Biodiversity and climate change : consequences for upper tree line in Slovakia ». Forestry Journal 62, no 3 (1 septembre 2016) : 181–85. http://dx.doi.org/10.1515/forj-2016-0022.
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Abstract Study of the effects of climate change on upper tree limit has mainly focused on the diversity of tree species as a result of the ability of species to tolerate temperature and moisture changes as well as some effects of disturbance regime changes. The tree species diversity changes due to climate change has been analysed via gap model and biodiversity indices. Gap models are individually based on simulations of establishment, growth, and mortality of each tree on the forest plot. Input ecological data for model calculations have been taken from the permanent research plots located in primeval forests in mountainous regions in Slovakia. The results of regional scenarios of the climatic change for the territory of Slovakia have been used, from which the values according to the CGCM3.1 (global) model, KNMI and MPI (regional) models. Model results for conditions of the climate change scenarios suggest a shift of the upper forest limit to the region of the present subalpine zone, in supramontane zone. The most significant tree species diversity changes have been identified for the upper tree line and current belt of dwarf pine (Pinus mugo) occurrence. Hill’s index of biodiversity in the upper forest line increased by 30 – 35% for horizon of 2050, resp. by 45 – 50% modeled for the horizon of 2075. Calculated values of Shannon’s index show an even higher increase due to climate change. For horizon 2050 is a roughly of three fold increase and horizon for 2075 by almost fivefold increase in the value of the index. Results from the gap model indicate the increase of tree species diversity 2 – 2,5 times.
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Markgraf, Vera. « Paleoenvironmental Changes at the Northern Limit of the Subantarctic Nothofagus Forest, lat 37°S, Argentina ». Quaternary Research 28, no 1 (juillet 1987) : 119–29. http://dx.doi.org/10.1016/0033-5894(87)90037-8.
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AbstractPaleoenvironmental changes dating back to before 10,000 yr B.P. at the northernmost occurrences of Nothofagus forests in Argentina at about latitude 37°S permit the reconstruction of past changes in the intensity of the winter rains, related to the southern westerlies that appear to determine the forest boundary. The paleoenvironmental interpretation is based on changes in the proportions of different Nothofagus species and changes in the ratio betwen forest and steppe taxa. The relatively most diverse and dense Nothofagus forest developed only during the last 4500 yr, prior to human impact during the last 300 yr. Before the middle Holocene, climatic conditions must have been different from the modern ones, with less overall precipitation judging from the overall lower amount of tree pollen and the reduction to primarily Nothfagus pumilio. An interval dated to older than 10,000 yr B.P. is characterized by co-occurrence of Prumnopitys andina, Nothofagus pumilio, and shrub-steppe taxa. Prumnopitys andina is known today only from scattered upper montane forest sites in Chile between 36° and 43°S lat and its ecological requirements are essentially unknown. The taxa combination, however, suggests that late-glacial climate must have been drier, and probably cooler than today. This implies that the winter rains and, consequently, the seasonal shift of the westerly circulation was reduced during the late Pleistocene and did not reach modern levels before 8500 yr B.P.
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Novotný, R., D. Černý et V. Šrámek. « Nutrition of silver fir (Abies alba Mill) growing at the upper limit of its occurrence in the Šumava National Park and Protected Landscape Area ». Journal of Forest Science 56, No. 9 (30 septembre 2010) : 381–88. http://dx.doi.org/10.17221/87/2009-jfs.
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In the second half of 20<sup>th</sup> century silver fir regeneration has been observed throughout all of the Europe, including the Czech Republic. The Bohemian Forest – Šumava Mts. is one of the regions where the silver fir percentage in forest stands is supposed to be increased from the present 2% to nearly 12%. During the period 2006–2007, in the Czech part of the Bohemian Forest, samples of silver fir were taken mainly in the upper altitudinal limit of silver fir occurrence. In the present paper the results of performed analyses are compared with similar surveys conducted in the other European regions. Samples from the Bohemian Forest, in contrast to other results, differ in higher phosphorus content and lower contents of calcium and manganese. Nitrogen content is slightly higher. Our values for the other elements (magnesium, potassium, zinc, sulphur) are comparable to those reported in Poland and Slovakia. In Germany, aside from the above mentioned differences, higher magnesium content was also found within the locality sampled.
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Silva, Lucas C. R., Geng Sun, Xia Zhu-Barker, Qianlong Liang, Ning Wu et William R. Horwath. « Tree growth acceleration and expansion of alpine forests : The synergistic effect of atmospheric and edaphic change ». Science Advances 2, no 8 (août 2016) : e1501302. http://dx.doi.org/10.1126/sciadv.1501302.
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Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems.
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Moravčík, M. « Derivation of target stocking for forests of Norway spruce vegetation zone in Slovakia ». Journal of Forest Science 53, No. 8 (7 janvier 2008) : 352–58. http://dx.doi.org/10.17221/2183-jfs.
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The present paper deals with derivation of target stocking in forests of Norway spruce vegetation zone. Target stocking in forests with prevailing ecological and social functions is the stocking when the forest fulfils demanded functions in the best way. For forests in the Norway spruce vegetation zone target stocking was derived by original procedures as an optimum stocking in harmonization of demands on the fulfilment of ecological functions (especially erosion control, hydrological and water protection ones), securing static stability and preconditions for the formation and growth of natural regeneration. We investigated the relations between stocking and indicators of static stability (slenderness coefficient and ratio of crown length to tree height), natural regeneration phases, ground and non-wood vegetation coverage and natural regeneration coverage. The most favourable status of these indicators was found out in stocking 0.7 and in the upper forest limit 0.6.
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Vacek, S., I. Nosková, L. Bílek, Z. Vacek et O. Schwarz. « Regeneration of forest stands on permanent research plots in the Krkonoše Mts. » Journal of Forest Science 56, No. 11 (1 décembre 2010) : 541–54. http://dx.doi.org/10.17221/65/2010-jfs.
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The article describes natural, combined and artificial regeneration on 38 permanent research plots in both Czech and Polish part of the Krkonoše Mts. The attention is paid to species composition, spatial (horizontal and vertical) and age structure of forest regeneration according to different stand and site conditions. Concerning the structure and dynamics of forest stands and their regeneration, the potential and prospects of regeneration according to particular developmental stages and stand types (beech stands; mixed stands: spruce-beech, fir-beech, spruce-fir-beech; spruce stands, stands in the ecotone of the upper forest limit and relict pine woods) were evaluated. In many aspects the plots show several similarities, nevertheless the regeneration in different site and stand conditions show clear differences in dynamics of development. The main differences are result of different ecological conditions, environmental limits and biological characteristics of dominant tree species.
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Ziegler, Justin P., Chad M. Hoffman, Brandon M. Collins, Jonathan W. Long, Christa M. Dagley et William Mell. « Simulated Fire Behavior and Fine-Scale Forest Structure Following Conifer Removal in Aspen-Conifer Forests in the Lake Tahoe Basin, USA ». Fire 3, no 3 (9 septembre 2020) : 51. http://dx.doi.org/10.3390/fire3030051.
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Quaking aspen is found in western forests of the United States and is currently at risk of loss due to conifer competition at within-stand scales. Wildfires in these forests are impactful owing to conifer infilling during prolonged fire suppression post-Euro-American settlement. Here, restoration cuttings seek to impact wildfire behavior and aspen growing conditions. In this study, we explored how actual and hypothetical cuttings with a range of conifer removal intensity altered surface fuel and overstory structure at stand and fine scales. We then simulated wildfires, examining fire behavior and effects on post-fire forest structures around aspen trees. We found that conifer removal constrained by lower upper diameter limits (<56 cm) had marginal effects on surface fuel and overstory structure, likely failing to enhance resource conditions sufficiently to sustain aspen. Increasing the diameter limit also led to a higher likelihood of fire spread and a higher rate of spread, owing to greater within-canopy wind speed, though crown fire activity decreased. Our simulations suggest heavier treatments could facilitate reintroduction of fire while also dampening the effects of wildfires on forest structure. Cutting specifications that relax diameter limits and remove a substantial portion of conifer overstory could better promote aspen restoration and mitigate fire hazard.
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Anderson, Patricia M., Anatoly V. Lozhkin, Berta V. Belaya, Olga Yu Glushkova et Linda B. Brubaker. « A lacustrine pollen record from near altitudinal forest limit, Upper Kolyma Region, northeastern Siberia ». Holocene 7, no 3 (septembre 1997) : 331–35. http://dx.doi.org/10.1177/095968369700700309.
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Dhaundiyal, Alok, et Suraj B. Singh. « Parametric Study of NTH Order Distributed Activation Energy Model for Isothermal Pyrolysis of Forest Waste Using Gaussian Distribution ». Acta Technologica Agriculturae 20, no 1 (1 mars 2017) : 23–28. http://dx.doi.org/10.1515/ata-2017-0005.
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Abstract This paper deals with the influence of some factors relevant to isothermal pyrolysis of residual leaves of Cedrus deodara on the asymptotic solution of the non-isothermal nth order distributed activation energy model (DAEM) using Gaussian distribution. Frequency factor, integral upper limit, the reaction order and the variance of Gaussian distribution are the parameters taken under purview of this study. In order to determine the kinetic parameters of the isothermal nth order Gaussian DAEM from thermoanalytical data of loose biomass pyrolysis, the variation of these factors has been considered. The obtained results show that the predicted results for nth order DAEM hold good at upper limit of dE, E∞ = 39 kJ mol-1.
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Cierjacks, Arne, Juan Enrique Iglesias, Karsten Wesche et Isabell Hensen. « Impact of sowing, canopy cover and litter on seedling dynamics of two Polylepis species at upper tree lines in central Ecuador ». Journal of Tropical Ecology 23, no 3 (24 avril 2007) : 309–18. http://dx.doi.org/10.1017/s0266467407004051.
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Failure of reproduction is hypothesized as being a main reason for the formation of upper tree lines but there is, as yet, little supportive evidence of such. This study investigates the effects of experimental sowing, canopy cover and litter depth on seedling emergence and survival of Polylepis incana and Polylepis pauta at the upper distribution limit of the species in the Páramo de Papallacta, central Ecuador. We established 18 study plots located in the interior, at the edge and at the exterior of closed forests at the upper tree line and analysed seedling dynamics for 1 y following experimental sowing with four different litter treatments. For both species, seedling numbers were significantly higher in the forest interior than outside, and higher in the treatments with the litter layer removed. In P. pauta, sowing significantly increased seedling number, which was more pronounced within and at the edge of the forest than outside. In contrast, there was no impact of sowing on seedling emergence in P. incana. First-year seedling survival and mean growth rate per month were low in both species. Log-linear models did not reveal significant interactions between survival and canopy cover or litter removal. Our data show that seedling recruitment is limited at the upper tree line – presumably due to extreme climatic conditions – which indicates the importance of constraints in sexual regeneration for tree-line formation in central Ecuador.
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Rosmaeni, Rosmaeni, Daud Malamassam, Hazairin Zubair et Mursyid Mursyid. « SOIL EROSION OVER DIFFERENT SLOPES UNDER PINE STANDS ». Indonesian Journal of Forestry Research 9, no 2 (31 octobre 2022) : 265–76. http://dx.doi.org/10.20886/ijfr.2022.9.2.265-276.
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Forests have an important role in controlling soil erosion. Pine stands are considered effective in controlling erosion due to high interception and thick litter. This study compares the level of erosion on land with a slope > 40% to land with a slope <40%, as one of the references used in reviewing standards for determining the slope of a protected forest area. The study was conducted from November 2016 to February 2017, under Pinus merkusii stand in the Education Forest of Hasanuddin University in Maros Regency. Erosion was measured in a land of 22 m x 4 m having long slopes > 40% and < 40% with 3 replicates. Surface runoff was measured during rain and suspension levels was determined based on a dry oven heated at 105°C. Actual erosion (gr) is calculated by multiplying total runoff volume (m3/plot) by suspension level (gr/m3). The results show the average erosion on the slopes >40% was 54.94 g/plot or 0.006 tons/ha while on the slopes <40% was 36.74 g/plot or 0.004 tons/ha. The average difference of the two test results, with a 95% confidence interval, shows differences in the erosion average on the slopes> 40% and <40%. However, when there is an increase in the percentage of canopy cover the erosion becomes smaller even on the slopes > 40%. This research can be used as a reference for considering the increase in the upper limit of the slope of the protected forest area, and the need for further evaluation on the existing upper limit value.
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Moravčík, M. « Derivation of target structure for forests of Norway spruce vegetation zone in Slovakia ». Journal of Forest Science 53, No. 6 (7 janvier 2008) : 267–77. http://dx.doi.org/10.17221/2018-jfs.
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Forests of the Norway spruce altitudinal vegetation zone occur on the upper limit of tree vegetation and they fulfil important ecological and social functions. A great part of these forests are man-made ones with changed age and spatial structure. The basic objective of the care of these forests is improvement or regeneration of their structure so that it will approach the structure of natural and primeval forests. Maximum fulfilment of their basic functions should be ensured in this way. Therefore following the analysis of our own empirical material the target structure of these forests was derived. Outlook target structure was derived so that it would correspond to the state of the most preserved forest ecosystems occurring in the spruce vegetation zone. Achievable target structure was defined for man-made forests with entirely changed structure.
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Gotsch, S. G., S. D. Crausbay, T. W. Giambelluca, A. E. Weintraub, R. J. Longman, H. Asbjornsen, S. C. Hotchkiss et T. E. Dawson. « Water relations and microclimate around the upper limit of a cloud forest in Maui, Hawai'i ». Tree Physiology 34, no 7 (1 juillet 2014) : 766–77. http://dx.doi.org/10.1093/treephys/tpu050.
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Kranabetter, J. M., A. Banner et A. de Groot. « An assessment of phosphorus limitations to soil nitrogen availability across forest ecosystems of north coastal British Columbia ». Canadian Journal of Forest Research 35, no 3 (1 mars 2005) : 530–40. http://dx.doi.org/10.1139/x04-192.
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The wet, slow-growing forests of western redcedar (Thuja plicata Donn ex D. Don) and salal (Gaultheria shallon Pursh) on the north coast of British Columbia are characteristically low in available phosphorus (P) compared with more productive forest ecosystems. It has been suggested that declining P availability can eventually limit soil biological activity and restrict nitrogen (N) cycling. We investigated this potential link between P availability and N cycling for three forest types (cedarsalal, hemlock lanky moss and spruce sword fern) covering a wide gradient in site productivity. Forest floors (upper 20 cm) and mineral soils (20 cm depth) were collected from five replicate sites of each forest type and incubated for 20 weeks at field moisture content with and without an amendment of NaH2PO4. We found that organic P concentrations of both forest floors and mineral soils were positively correlated to extractable inorganic N concentrations (unamended soils over 20 weeks). The addition of P to the low-productivity cedarsalal soils led to significant increases in extractable inorganic N in the forest floors and mineral soils. P amendments led to either a smaller or nonsignificant increase in extractable N for moderately and highly productive soils. Soil respiration of CO2 and respiration quotients were substantially reduced in forest floors with a P amendment, suggesting N mineralization was governed by exoenzyme allocation rather than decomposition rates. These results demonstrate a possible enhancement in N supplies with an application of P to low-productivity cedarsalal forests.
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Chiodi, Andrew M., Narasimhan K. Larkin, J. Morgan Varner et J. Kevin Hiers. « Sensitivity of prescribed burn weather windows to atmospheric dispersion parameters over southeastern USA ». International Journal of Wildland Fire 28, no 8 (2019) : 589. http://dx.doi.org/10.1071/wf18209.
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Prescribed burning is an essential tool for forest and rangeland management that requires specific weather conditions to enable the efficient and safe application of fire. Prescribed burning is often limited by the ability to find suitable burn-days that fit within the identified weather parameters that balance good smoke dispersion and erratic fire behaviour. We analysed the sensitivity of the occurrence of widely used weather windows in the southeastern USA to modest changes in how they are defined. This analysis identified the most limiting prescription components and assessed where small changes in the prescription window can yield the greatest gains in additional burn-days. In the growing season (April–September), adjustments to mixing height offered the greatest such opportunity: a 12.5% increase in the upper-limit yields ~25% more burn-days during this period. During the dormant season (November–January), a 12.5% change in the upper-limit of transport wind yields ~20% more burn-days. Performing this analysis on the ventilation index revealed that comparable increases in burn-days were available by changing its upper limits. These results help inform ongoing discussions on potential changes to regional prescribed burn weather parameters that might help meet smoke management and treatment objectives in the southeastern USA and more broadly.
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Dhaundiyal, Alok, et Suraj B. Singh. « Distributed activation energy modelling for pyrolysis of forest waste using Gaussian distribution ». Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. 70, no 2 (1 avril 2016) : 64–70. http://dx.doi.org/10.1515/prolas-2016-0011.
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Abstract The paper focuses on the influences of some factors significant to pyrolysis of forestry biomass on the asymptotic solution of the non-isothermal nth-order distribution energy model (DAEM) using Gaussian distribution. Investigated parameters are the integral upper limit, the frequency factor, and the heating rate parameters of the Gaussian distribution. The influence of these factors has been used for evaluating the kinetic parameters of the non-isothermal nth-order Gaussian distribution from thermogravimetric analysis of forest waste.
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Nikolaeva, Svetlana, Dmitry Savchuk, Aleksandr Kuznecov et Elena Filimonova. « Structure of high elevation forests in Katunsky Range (the Altai Mountains) ». Forestry Engineering Journal 13, no 4 (17 avril 2024) : 137–55. http://dx.doi.org/10.34220/issn.2222-7962/2023.4/21.
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High elevation forests are both a good natural object for studying the forest dynamics and a sensitive indicator of the impact of various external factors on them. These forests on the Katunsky Range of the Altai Mountains have been studied extremely poorly. The purpose of the work is to describe the size and age structure of tree stands of forest communities and to reveal the effect of environmental factors on them in the upper part of the forest belt of the Katunsky Range (the Altai Mountains) using the Akkem glacial basin as an example. Six sample areas of 0.05-0.12 ha were used at two altitude levels (2065-2080 and 2220-2240 m a.s.l.). A total of 232 adult trees and 209 saplings and seedlings were examined, aged 86 and 180, respectively. The size and age structure of the forest stand and saplings and seedlings has been established. Three main generations of trees that established on the valley slopes have been identified in the forest stand (the first generation is trees of 530-580 years old, the second is the trees of 270-410 years old, and the third is trees of 30-120 years old) and one additional generation (130-170 years old). They established at the end of the Medieval warming (XV-XVI centuries), during the Little Ice Age (XVII-mid-XIX centuries), and during the warming which began in the mid-XIX centuries. Factors have been identified that limit the spread and the structure of the high elevation forests: geomorphological, wildfires, logging.
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Savchuk, D. A., E. E. Timoshok, E. O. Filimonova et S. A. Nikolaev. « Dynamics of the upper forest limit on the Katunsky ridge (Altai Mountains) over the past 120 years ». Экология, no 6 (1 novembre 2023) : 416–21. http://dx.doi.org/10.31857/s0367059723060082.
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The temporal dynamics of the upper forest boundary in the oroclimatic conditions of the Katunsky Range is described using the example of the Akkem mountain-glacial basin over the past 120 years. Changes in the density of trees and undergrowth of cedar and larch on the eastern and western slopes, the origin and features of the formation of dense and sparse groups and external factors influencing their formation are considered.
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Burrows, N. D. « Flame residence times and rates of weight loss of eucalypt forest fuel particles ». International Journal of Wildland Fire 10, no 2 (2001) : 137. http://dx.doi.org/10.1071/wf01005.
Texte intégralRésumé :
Shape, size, composition and arrangement of fuel particles within a fuel array significantly affect the way in which wildland fires behave. Australian eucalypt forest fire behaviour models characterise fine fuels according to the quantity burnt in the flaming zone, and the upper size limit for fine fuel particles is somewhat arbitrarily set at 6 mm for the McArthur Forest Fire Danger Meter and 10 mm for the Forest Fire Behaviour Tables for Western Australia. Flame residence time and rate of weight loss during combustion of dry eucalypt leaves and different dimensions of round wood were measured to provide a scientific basis for standardising litter fuel sampling in dry eucalypt forests. Eucalypt leaves burnt at a rate equivalent to a piece of 4 mm diameter round wood, with smaller diameter round wood being the most flammable component of the fuel array. Based on flame residence times of individual fuel particles measured in the laboratory, and eucalypt surface fuel arrays observed in the field, fine litter fuel sampling should be standardised to leaves and round wood less than 6 mm in diameter. This study also enables the determination of the contribution of larger fuel particles to flaming zone combustion and intensity.
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Kucsicsa, Gheorghe, et Dan Bălteanu. « The influence of man-induced land-use change on the upper forest limit in the Romanian Carpathians ». European Journal of Forest Research 139, no 6 (29 mai 2020) : 893–914. http://dx.doi.org/10.1007/s10342-020-01293-5.
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Chiu, Ching-An, Chyi-Rong Chiou, Jian-Rong Lin, Po-Hsiung Lin et Cheng-Tao Lin. « Coldness index does not indicate the upper limit of evergreen broad-leaved forest on a subtropical island ». Journal of Forest Research 19, no 1 (février 2014) : 115–24. http://dx.doi.org/10.1007/s10310-013-0396-z.
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Suetina, Yulia G. « Distribution of lichen thalli Pseudevernia furfuracea (L.) Zopf along Pinus sylvestris trunk in different types of pine forests with different relief positions ». Samara Journal of Science 9, no 3 (20 novembre 2020) : 137–41. http://dx.doi.org/10.17816/snv202093122.
Texte intégralRésumé :
The research of the Pseudevernia furfuracea population was carried out in the Mari El Republic on the territory of the Mari Chodra National Park. The lichen-mossy and cowberry pine forests were studied with different relief positions: uplands and lowlands. The paper discusses the use of two indicators of population density: D₁ is a number of thalli on the tree; D₂ is a number of thalli in the substrate area. The distribution of thalli along the trunk of Pinus sylvestris depends on the characteristics of the stand, characteristics of the tree and the position of the trees in the relief. In a well-lightened lichen-mossy pine forest the distribution of the number of thallus is equal at different exposures, but it is different due to the heights of the trunk. The maximum number of thalli is typical for a height of 0,51 m. The most number of thallus grows at the southern and western expositions in less lightened cowberry pine forests. There is a shift in the height of the number of thallus to a height of 11,5 m. There is a dependence of the upper boundary of the thallus distribution along the trunk on the height of the lamellar bark. The highest upper limit of thallus growth (a height of 4,8 m) is typical for the lowering of the lichen-mossy pine forest, where the lamellar bark rises to a height of 7,2 m. The lower boundary of the thallus settlement depends on microclimatic factors. Among them the decisive factor is light. The smallest lower boundary of a thallus settlement (a height of 0,2 m) is typical for an elevation in a lichen-mossy pine forest. This habitat has the highest population density of P. furfuracea.
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Luther, Joan E., Richard A. Fournier, Mélanie Houle, Antoine Leboeuf et Douglas E. Piercey. « Application of shadow fraction models for estimating attributes of northern boreal forests ». Canadian Journal of Forest Research 42, no 9 (septembre 2012) : 1750–57. http://dx.doi.org/10.1139/x2012-118.
Texte intégralRésumé :
A shadow fraction method was developed previously for mapping forest attributes of northern black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) forests. This paper evaluates application of the method for (i) balsam fir stands ( Abies balsamea (L.) Mill.), (ii) stands with higher volume and biomass than those of previous studies, and (iii) stands with a higher composition of deciduous trees and steeper slopes. Models developed for new test sites in (i) central Labrador and (ii) western Newfoundland were not statistically different from previous models for biomass, volume, and basal area. Relative root mean square errors (RMSEr) for central Labrador were slightly lower than those found in other test sites (RMSEr: 24%–29%) but higher for western Newfoundland (RMSEr = 37%–43%), attributed to the higher upper limit of measured attributes and increased presence of deciduous trees. Results suggest that reasonable estimates can be generated for conifer forests of northeastern Canada; however, an alternative solution is needed where mixed and deciduous stands are prevalent. Measurement of ground plots over a wider range of species composition and forest structure is recommended for broader application to northern boreal forests and to further assess the potential role of the shadow fraction method in national-scale inventory programs.
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Treml, Václav, Jan Wild, Tomáš Chuman et Markéta Potůčková. « Assessing the Change in Cover of Non-Indigenous Dwarf-Pine Using Aerial Photographs, a Case Study from the Hrubý Jeseník Mts., the Sudetes ». Journal of Landscape Ecology 3, no 2 (1 janvier 2010) : 90–104. http://dx.doi.org/10.2478/v10285-012-0029-9.
Texte intégralRésumé :
Assessing the Change in Cover of Non-Indigenous Dwarf-Pine Using Aerial Photographs, a Case Study from the Hrubý Jeseník Mts., the SudetesIn addition to ongoing climate change, alpine ecosystems are also threatened by the expansion of non-indigenous species. Expansion of dwarf pine (Pinus mugoTurra) in the Hrubý Jeseník Mts. is an excellent example of the interactions between a planted alpine shrub and alpine ecosystems dominated by grassland species. Based on a comparison of aerial photographs taken in two different periods (1971/73 and 2003) we analyzed spatial changes in the dwarf pine cover. We focused on an evaluation of the current proportion of dwarf pine stands above the upper forest limit, as well as on the effects of stand texture and environmental variables on dwarf pine expansion over this 30 year period. During this time, dwarf pine stands increased their extent by 63%. Small forest-free areas above the upper forest limit in the northern part of the Hrubý Jeseník ridge are currently covered by dwarf pine on more than 30% of their surface. Expansion of dwarf pine was fastest in open, fine-grained stands, often situated in lower altitudes and on north- to east-facing slopes. The dwarf pine expansion was more intense than predicted by simple model of vegetative growth, especially within open stands with short polycormon margins in low altitudes. This might be explained by more intensive growth in less extreme environment and/or by higher generative reproduction on these sites. Finally, we suggest that expanding dwarf pine shrubs and recessing grassland patches negatively affects the abundance of heliophilous alpine plants and insects. We believe that the results of this study could be relevant to ongoing discussions on the management of summit forest-free areas in the Hrubý Jeseník Mts.
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Zymaroieva, Anastasiia, Oleksandr Zhukov, Tetiana Fedoniuk, Tetyana Pinkina et Volodymyr Vlasiuk. « Edaphoclimatic factors determining sunflower yields spatiotemporal dynamics in northern Ukraine ». OCL 28 (2021) : 26. http://dx.doi.org/10.1051/ocl/2021013.
Texte intégralRésumé :
The climate and soil conditions have a significant impact on sunflower yields. Sunflower yield dynamics in the Central European mixed forests (Polissya) and Eastern European forest-steppe ecoregions in Ukraine from 1991 to 2017 was proved to fit a log-logistic model most adequately. The model has four characteristic parameters: the Lower Limit indicates the lowest level of yield over the study period; the Slope indicates the rate of yield increase over time; the ED50 is the time required to reach half of the maximum yield level and simultaneously the point with the highest rate of yield increase; the Upper Limit shows the highest yield level. The parameters of the yield model are used to meaningfully interpret the causes of yield dynamics. Edaphoclimatic factors account for 34 to 58% of the variation in the yield trend parameters. The soil texture and soil organic carbon (SOC) predominate among the edaphic factors that determine the variability of sunflower yield. Continentality of climate and degree of temperature variability during the growing season are the main climatic determinants of sunflower yield parameters.
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Pasha, Ghufran Ahmed, et Norio Tanaka. « Effectiveness of Finite Length Inland Forest in Trapping Tsunami-Borne Wood Debris ». Journal of Earthquake and Tsunami 10, no 04 (octobre 2016) : 1650008. http://dx.doi.org/10.1142/s1793431116500081.
Texte intégralRésumé :
Debris produced by coastal forest destruction due to the tsunami after the Great East Japan Earthquake caused secondary damage to buildings by collision. To limit such destruction, the trapping action of a finite-length forest was examined in a flume considering the effects of ‘forest density’, ‘debris length to forest width ratio’, and ‘forest width-length ratio (aspect ratio)’ because the trapping height greatly affects the rate of damage to the forest itself. Higher forest density and a higher aspect ratio decrease the velocity in front of the forest. Debris having a specific gravity up to 0.80 floated after collision but oscillated vertically as forest density was increased. With debris of a higher specific gravity (0.90–1.05), increased forest density resulted in debris attachment closer to the ground, which reached a plateau beyond a forest density of 0.48 cylinders/cm2. In sparse forest, when debris was longer than the forest width; most debris fell at the foot of trees, while it was caught in the upper half of water depth in dense forest. The flow structure in front of and around a forest greatly affected the debris trapping capacity. It was deducted that the inland forest with a density of 0.48 cylinders/cm2 and an aspect ratio of 1.7 trapped most of the debris of all lengths at the foot of trees.
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Enzi, Wolfgang, Riccardo Murgia, Oliver Newton, Simona Vegetti, Carlos Frenk, Matteo Viel, Marius Cautun et al. « Joint constraints on thermal relic dark matter from strong gravitational lensing, the Ly α forest, and Milky Way satellites ». Monthly Notices of the Royal Astronomical Society 506, no 4 (10 juillet 2021) : 5848–62. http://dx.doi.org/10.1093/mnras/stab1960.
Texte intégralRésumé :
ABSTRACT We derive joint constraints on the warm dark matter (WDM) half-mode scale by combining the analyses of a selection of astrophysical probes: strong gravitational lensing with extended sources, the Ly α forest, and the number of luminous satellites in the Milky Way. We derive an upper limit of λhm = 0.089 Mpc h−1 at the 95 per cent confidence level, which we show to be stable for a broad range of prior choices. Assuming a Planck cosmology and that WDM particles are thermal relics, this corresponds to an upper limit on the half-mode mass of Mhm < 3 × 107 M⊙ h−1, and a lower limit on the particle mass of mth > 6.048 keV, both at the 95 per cent confidence level. We find that models with λhm > 0.223 Mpc h−1 (corresponding to mth > 2.552 keV and Mhm < 4.8 × 108 M⊙ h−1) are ruled out with respect to the maximum likelihood model by a factor ≤1/20. For lepton asymmetries L6 > 10, we rule out the 7.1 keV sterile neutrino dark matter model, which presents a possible explanation to the unidentified 3.55 keV line in the Milky Way and clusters of galaxies. The inferred 95 percentiles suggest that we further rule out the ETHOS-4 model of self-interacting DM. Our results highlight the importance of extending the current constraints to lower half-mode scales. We address important sources of systematic errors and provide prospects for how the constraints of these probes can be improved upon in the future.
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Kučera, Peter. « On the Occurrence of Natural Norway Spruce Woodland in the Pieniny Mts (Western Carpathians) ». Acta Silvatica et Lignaria Hungarica 11, no 2 (1 décembre 2015) : 123–38. http://dx.doi.org/10.1515/aslh-2015-0010.
Texte intégralRésumé :
Abstract According to Kulczyński (1928), a natural Picea abies forest occurs in the mountain range of the Pieniny Mts on the slopes of the mountain Vysoke skalky. Later, various data on the altitudinal range of this stand (and thus on the locality itself) were published: (1) 890 (900) - 950 m, (2) 1000 - 1050 m or (3) around 1000 m. The aim of the field research was to verify published data on the occurrence of a woodland of Upper Mountain Norway spruce (association Polysticho-Piceetum) in the territory of Vysoke skalky. A field study in the area has revealed that most of published data on the occurrence of the Kulczyński’s Picea woodland are incorrect, as its real upper altitudinal limit reaches ± 940 m. The main result is the confirmation of the real existence of a Vaccinium myrtillus-Homogyne alpina-Picea abies phytocoenosis in the territory of Vysoke skalky. However, tree species other than Picea abies (e.g. Fagus sylvatica, Abies alba, Acer pseudoplatanus) could persist in the special habitat of Kulczyński’s ‘Picea woodland’. The natural vegetation of this place was formed by mixed forest stand.
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Raspopina, Svitlana, Yuriy Debryniuk et Yuriy Hayda. « Forest plantation productivity – soil interactions within Western Forest-Steppe of Ukraine : effects of pH and cations ». Folia Forestalia Polonica 62, no 4 (1 décembre 2020) : 233–45. http://dx.doi.org/10.2478/ffp-2020-0023.
Texte intégralRésumé :
AbstractDark grey podzolized soils on the loess like loams, which are represented in the soil cover within fresh and humidity gradients in the Western Forest Steppe of Ukraine, are characterized by high forest vegetation potential, which ensure the formation of mostly pure and mixed larch and spruce stands with high level of the productivity. Despite the fact that both species are coniferous, their effect on the soil, in particular, on its acid-base indicators (actual and potential forms of acidity, sum of absorbed bases, degree of saturation of bases, content of mobile aluminium), which are important components of soil fertility, are specific. Due to the fact that there is a close interaction between forest plantations and soil properties, changing the participation of species in the stand, it is possible to adjust the actual soil fertility.The soils under both pure and mixed spruce and larch stands are characterized by a high level of potential acidity that reaches the high acidic values in the upper horizons. A similar reaction of soil solution under coniferous forests is caused by acid hydrolysis of aluminosilicates and accumulation of mobile Al in the rhizosphere zone. Simultaneously, the same acidic characteristics, including the presence of movable aluminium, are also found in soils under broadleaved plantations. In general, acid-exchange properties of soils (high potential acidity, unsaturation of bases and availability of movable aluminium) traditionally are considered as unfavourable for vegetation. However, our researches refute it and prove that within certain values, these indicators do not limit the productivity of pure and mixed spruce and larch stands.
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Campbell, Jocelyn, et Darwyn S. Coxson. « Canopy microclimate and arboreal lichen loading in subalpine spruce-fir forest ». Canadian Journal of Botany 79, no 5 (1 mai 2001) : 537–55. http://dx.doi.org/10.1139/b01-025.
Texte intégralRésumé :
Hair lichen communities in Engelmann spruce (Picea engelmannii) subalpine fir (Abies lasiocarpa) forests of the northern Cariboo Mountains (British Columbia) show distinct vertical zonation. Alectoria sarmentosa reaches peak abundance in the lower canopy (over 35 kg/ha) whereas Bryoria spp. lichens reach peak abundance in the upper canopy (over 250 kg/ha). These distribution patterns are accentuated by stand structure with trees growing in clumps retaining significantly higher lichen loading on a per branch basis compared to solitary trees. The vertical zonation of lichen communities is accompanied by distinct trends in canopy microclimate. Snowmelt events account for the largest proportion of observed thallus hydration in both Alectoria and Bryoria. Although canopy microclimate is surprisingly isothermal during rainfall events, the attenuation of thallus hydration after wetting is typically greater for lower canopy exposures. An important exception to this pattern is seen under midwinter conditions, when solar insolation is insufficient to sustain prolonged lower canopy snowmelt. Our data support the hypothesis that ventilation in upper canopy exposures is a contributing factor in the vertical zonation of Alectoria and Bryoria communities. Upper canopy Bryoria rely more heavily on snowmelt events to sustain thallus hydration, whereas lower canopy Alectoria utilize summer rainfall events to a greater extent. We hypothesize that physiological mechanisms, through which these patterns of canopy microclimate influence lichen zonation, may include an intolerance to prolonged wetting by Bryoria and higher resaturation respiration costs in Alectoria, which would limit it to more mesic canopy exposures. We believe that the observed distribution of canopy lichens ultimately reflects the long-term interaction of both physiological and successional processes (lichen colonization and dispersal) within the canopy.Key words: canopy, epiphytes, lichens, microclimate.
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Quizhpe, Wilson, Ángel Benítez, Klever Cuenca, Hernán Uvidia, Isau Huamantupa, Jesús Muñoz et Omar Cabrera. « Forest Diversity and Structure in the Amazonian Mountain Ranges of Southeastern Ecuador ». Diversity 11, no 10 (17 octobre 2019) : 196. http://dx.doi.org/10.3390/d11100196.
Texte intégralRésumé :
We analyze the structure of diameter, richness, and diversity of the forests in the upper limit of the great Amazon basin located in the Ecuadorian territory of the Cordilleras del Cóndor and Cutucú. Our hypothesis was that the forests of the eastern mountain ranges are not homogeneous, but rather present differences in their structure, richness, and floristic diversity. Our main objective was to classify the types of forests based on the characteristics of the diameter structure and the species composition of the Amazonian forests of the eastern mountain ranges in southern Ecuador, and we determined the influence of critical edaphic, environmental, and geomorphological factors, For this we installed eight permanent plots of one hectare in homogeneous and well preserved forest stands, four plots in the province of Zamora Chinchipe and four in the province of Morona Santiago. We identified and measured all trees >10 cm at chest height and for each plot, soil samples, as well as environmental and slope data were taken. We performed an non-metric multidimensional scaling analysis (NMDS) analysis to evaluate changes in climatic and geomorphological gradients, and used the CCA analysis to assess the relationship between the composition of the species at the plot level and the edapho-climatic variables. Finally, we modeled the change in diversity ad species (Fisher’s alpha) in relation to climatic, altitudinal, and geomorphological gradients using a GLM. We determined the existence of two different types of forest, the first called Terra Firme, characterized by the presence of a greater number of species and individuals per plot as compared to the second type of forest called Tepuy or Sandstone forest. Species richness was negatively correlated with the phosphorus content of the soil and the pH, annual average temperature, annual rainfall, and altitude. Terra Firme forests, settled in more stable and nutrient-rich climatic areas, were more diverse and Sandstone forests are poor in nutrients and develop in areas with greater seasonality.
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Belousov, Igor A., et Ilya I. Kabak. « Yalongaphaenops erwini gen. et sp. nov., the world’s most high-altitude hypogean trechine beetle from China (Coleoptera, Carabidae, Trechinae) ». ZooKeys 1044 (16 juin 2021) : 197–220. http://dx.doi.org/10.3897/zookeys.1044.62572.
Texte intégralRésumé :
A new genus and new species of carabid beetle, Yalongaphaenops erwinigen. et sp. nov., is described from mountains SW of Mianning City, Sichuan Province, China. This finding, from one side, extends the known distribution of Chinese hypogean trechines, and from another, it raises the upper limit of their vertical distribution to nearly 4000 m. Photographs of the habitus and major taxonomic characters, including the male genitalia, right mandible, and microsculpture patterns of the integument are supplied. The type locality of the new taxon is mapped. Yalongaphaenopsgen. nov. shows some similarities with the genus Shiqianaphaenops Tian, 2016 from eastern Guizhou and the genus Boreaphaenops Uéno, 2002 described from Hubei, China. However, the direct relationships of the new genus remain unclear. Further new discoveries of hypogean trechines in Sichuan are necessary to evaluate possible variation of major characters in allied taxa. Although Y. erwinisp. nov. was collected at an elevation exceeding 3800 m a.s.l., it conforms to the upper limit of the forest zone being approximately on par with the vertical distribution of some high altitude hypogean trechine species in other parts of the globe.
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Bonnefille, Raymonde, et Guy Riollet. « The Kashiru Pollen Sequence (Burundi) Palaeoclimatic Implications for the Last 40,000 yr B.P. in Tropical Africa ». Quaternary Research 30, no 1 (juillet 1988) : 19–35. http://dx.doi.org/10.1016/0033-5894(88)90085-3.
Texte intégralRésumé :
A continuous pollen record from a central African highland site (3°28′S, 29°34′E) with 15 radio-carbon dates spans at least the last 40,000 yr. Both modern and fossil pollen have been investigated. A clear pattern of changes in vegetation and climate is suggested. Prior to 30,000 yr B.P., the occurrence of the montane conifer forest, including the upper forest limit, indicates climatic conditions colder and drier than now, but more humid than in late-glacial time. Between 30,000 and 15,000 yr B.P., grassland with afroalpine indicators expanded down to 2500-2000 m altitude as a result of dry, and most probably cool, climate; the montane forest persisted in refuges, although much reduced. Forest vegetation with the same floristic composition as today appeared after 13,250 ± 200 yr B.P., suggesting more humid conditions. The occurrence of a possible short-term humid episode about 21,500 yr B.P. is correlated with some high lake-level stages in East Africa and with organic deposits in deep-sea cores from the Mediterranean and the Atlantic Ocean.
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Gaffarova, Liliya. « DYNAMICS OF HUMUS RESERVES AND FORECAST OF CARBON-INVESTING POTENTIAL OF ZONAL SOILS OF THE REPUBLIC OF TATARSTAN ». Vestnik of Kazan State Agrarian University 16, no 3 (21 novembre 2021) : 27–31. http://dx.doi.org/10.12737/2073-0462-2021-27-31.
Texte intégralRésumé :
The article analyzes the results of statistical processing of morphometric and agrochemical indicators of zonal soils of the Republic of Tatarstan based on the accumulated information of large-scale soil studies. The boundaries of genetic horizons are examined, the content of humus and its reserves within the limits of heavy loamy and clay varieties of arable soil subtypes is estimated. Arithmetic averages allow us to generalize the humus content in soils. So, in the series of sod-podzolic soils – light gray forest-gray forest – dark gray forest-podzolic chernozems – leached chernozems-typical soils in a layer of 0-30 cm on average contains 2,20; 2,58; 3,76; 4,76; 6,8; 7,6; 7,2 % humus. The observed patterns of humus accumulation in soils are also preserved in the distribution of its reserves – 85; 97; 140; 162; 233; 257; 240 tons per he-1. It is proposed to characterize the general population along the boundaries of typical values that fit into the 50% confidence interval to assess the overall range of spatial variability of humus indicators. The upper limit of the typicity will correspond to the greatest accumulation of humus with a combination of local features of soil formation factors and can serve as a guide for predicting carbon sequestration in the soils of this region. Accordingly, the carbon-sequestering potential of sod-podzolic soil and typical chernozem is-20 tons per he-1, light gray forest soil-22 tons per he-1, gray forest soil and leached chernozem-27 tons per he-1, the highest values in dark gray forest soil are more than 30 tons per he-1
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Rivest, Sébastien, et Mark Vellend. « Herbivory and pollen limitation at the upper elevational range limit of two forest understory plants of eastern North America ». Ecology and Evolution 8, no 2 (12 décembre 2017) : 892–903. http://dx.doi.org/10.1002/ece3.3397.
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Erickson, Michael D., David D. Reed et Gleen D. Morz. « Stand Development and Economic Analysis of Alternative Cutting Methods in Northern Hardwoods : 32-Year Results ». Northern Journal of Applied Forestry 7, no 4 (1 décembre 1990) : 153–58. http://dx.doi.org/10.1093/njaf/7.4.153.
Texte intégralRésumé :
Abstract Changes in stand quality and financial returns are evaluated for Upper Michigan northern hardwood stands managed for 32 years under eight alternative cutting techniques. Improvements in tree grade and stand soundness were greatest under a light improvement cutting method which support recommendations that bole quality improvement can be attained through selection type cuttings. Harvest revenues were maximized by a 12-in. diameter limit cut, followed by a 16-in. diameter limit and a light improvement cutting. In contrast, the managed forest value, assuming sustainable stand conditions have been achieved for all treatments, was maximized by the 16-in. diameter limit cut, followed closely by the light improvement treatment. Although the 16-in. diameter limit cut provided returns slightly greater than the light improvement cut and had a more even flow of revenues, it did not lead to quality improvements. These results support those of other studies which indicate the importance of considering economic criteria in developing silvicultural recommendations. North. J. Appl. For. 7:153-158, December 1990.
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Piergiacomo, Federica, Luigimaria Borruso, Sonia Ciccazzo, Stefano Rizzi, Stefan Zerbe et Lorenzo Brusetti. « Environmental Distribution of AR Class 1 Integrons in Upper Adige River Catchment (Northern Italy) ». International Journal of Environmental Research and Public Health 17, no 7 (30 mars 2020) : 2336. http://dx.doi.org/10.3390/ijerph17072336.
Texte intégralRésumé :
The source of antibiotic residuals can be directly related to the presence of municipal or industrial wastewater and agricultural activities. Antibiotics can trigger the dissemination of antibiotic resistance genes within bacterial communities. The mobile genetic elements Class 1 integrons (intl1 region) has been already found to be correlated with a wide range of pollutants (i.e., antibiotics, heavy metals), and hence, it has been proposed as a proxy for environmental health. This study aimed to assess the presence of intl1 in different environmental matrices, including agricultural and forest soils, freshwater and unpolluted sediments in the upper Adige River catchment (N Italy), in order to identify the spread of pollutants. Intl1 was detected by direct PCR amplification at different frequencies. The urban and agricultural areas revealed the presence of intl1, except for apple orchards, where it was below the detection limit. Interestingly, intl1 was found in a presumed unpolluted environment (glacier moraine), maybe because of the high concentration of metal ions in the mineral soil. Finally, intl1 was absent in forest fresh-leaf litter samples and occurred with low rates in soil. Our results provide new data in supporting the use of intl1 to detect the environmental health of different land-use systems.
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Yang, Da, Ai-Ying Wang, Jiao-Lin Zhang, Corey J. A. Bradshaw et Guang-You Hao. « Variation in Stem Xylem Traits is Related to Differentiation of Upper Limits of Tree Species along an Elevational Gradient ». Forests 11, no 3 (20 mars 2020) : 349. http://dx.doi.org/10.3390/f11030349.
Texte intégralRésumé :
The distribution limits of many plants are dictated by environmental conditions and species’ functional traits. While many studies have evaluated how plant distribution is driven by environmental conditions, there are not many studies investigating xylem vessel properties with altitude, and whether these traits correlate with altitudinal distribution of tree. Here, we investigated the upper limits of distribution for ten deciduous broadleaf tree species from three temperate montane forest communities along a large elevational gradient on the north-facing slope of Changbai Mountain in Northeast China. We measured stem xylem traits associated with a species’ ability to transport water and resist freezing-induced cavitation that theoretically represent important adaptations to changes in climatic conditions along the elevational gradient. Hydraulically weighted vessel diameter (Dh) was negatively correlated with with the upper limit across the ten studied tree species; however, the correlation seems to be driven by the large differences between ring- and diffuse-porous tree species groups. The ring-porous tree species (e.g., Fraxinus mandshurica Rupr., Maackia amurensis Rupr. et Maxim., and Phellodendron amurense Rupr.) had considerably wider vessels than the diffuse-porous species and were all limited to low-elevation communities. The coefficient of variation (CV) for Dh was 0.53 among the 10 studied species, while the intraspecific analysis showed that the highest CV was only 0.22 among the 10 species. We found no evidence of a relationship between Dh and the upper limits across the seven diffuse-porous species. In contrast to elevation, hydraulic-related xylem traits had no clear patterns of change with precipitation, indicating that hydraulic functionality was largely decoupled from the influences of precipitation in the study area. This finding suggests that xylem traits are associated with altitudinal limits of species distribution, which is mostly evidenced by the contrasts between ring- and diffuse-porous species in xylem anatomy and their altitudinal distributions.
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Creão-Duarte, Antonio José, Alessandre Pereira-Colavite, Wellington Emanuel Dos Santos, Suênia Alcântara Barbosa, Valberta Alves Cabral, Aline Lourenço, Izabela Souza Braga et Wylma Regina Da Silva. « Membracidae diversity (Hemiptera : Auchenorrhyncha) in an Atlantic Forest area, Paraíba, Brazil, with preliminary comments on collection methods, spatial distribution and estimated species richness ». Boletim do Museu Paraense Emílio Goeldi - Ciências Naturais 12, no 1 (15 septembre 2020) : 11–21. http://dx.doi.org/10.46357/bcnaturais.v12i1.402.
Texte intégralRésumé :
In order to document the Membracidae of an area of the Brazilian Atlantic Forest in Paraíba, four collection methods were employed, distributed in 100 sample units during ten days in November 2014. A total of 1,182 membracids of 27 species were collected. The assemblages were marked with a high dominance, since six species accounted for 80.63% of the total number of individuals captured. Species with more than ten individuals were associated with the three environments of the forest: canopy, understory, and edge. The importance of the four sampling methods in the final membracid composition was evaluated through the Jaccard similarity index and its complement, where the values of complementarity were superior to the values of similarity, suggesting the dissimilarity of assemblages inventoried by each method. The observed richness corresponds to 90.0% and 79.4% of the richness estimated by Chao1 and Chao2. The richness estimated by Chao1 is within the upper limit of the confidence interval (95%) in the last plot of the species accumulation curve, while the richness estimated by Chao2 is above this limit. The additional sampling effort needed to collect 95% of the estimated richness is 969 individuals for Chao1 and 317 sample units for Chao2.
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Gabbasova, D. T., P. S. Shirokikh, I. G. Bikbaev et N. I. Fedorov. « TEMPERATURE AND MOISTURE CHANGES IN FOREST COMMUNITIES ALONG THE ELEVATION GRADIENT ON BOLSHOI SHATAK MOUNTAIN ». ÈKOBIOTEH 6, no 3 (2023) : 166–74. http://dx.doi.org/10.31163/2618-964x-2023-6-3-166-174.
Texte intégralRésumé :
Due to climate change, there is an increase in mean annual temperatures, which affects the altitudinal distribution of vegetation in the mountains. The purpose of this study was to investigate temperature and humidity changes along the altitudinal gradient on the Bolshoi Shatak mountain range from the foot of the mountain to the upper limit of forest distribution. Temperature and relative humidity data were collected using DS1923-F5 loggers in pine-broadleaf, birch-pine and larch forest located at altitudes of 631, 831 and 966,46 m msl, respectively. No abnormal winter temperatures were observed during the study period. The duration of the frost-free period was 157 days in the pine-broadleaf forest, 151 days in the birch-pine forest and 143 days in the larch forest. In the summer period of 2021 there was a summer drought, which was manifested to an equal extent in the sample plots in pine-birch and larch forest and to a lesser extent in pine-broadleaved forest. In the rainfall-normal year 2022, humidity content was significantly higher in pine-birch forest than in larch forest. Thus, the factors influencing the distribution of broad-leaved species at present may be the humidity regime and shorter frost-free period above the boundary of their current distribution. Further monitoring using loggers is needed to make a final conclusion on the contribution of individual factors to the current distribution of broad-leaved species.
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Korpela, Ilkka Sakari, et Timo Erkki Tokola. « Potential of Aerial Image-Based Monoscopic and Multiview Single-Tree Forest Inventory : A Simulation Approach ». Forest Science 52, no 2 (1 avril 2006) : 136–47. http://dx.doi.org/10.1093/forestscience/52.2.136.
Texte intégralRésumé :
Abstract Two aerial image-based estimation chains were compared for their potential in the assessment of timber resources. The two chains consisted of two- and three-dimensional image measurements followed by indirect model estimation. The effects of various errors at both the single-tree and stand levels were examined with Monte Carlo simulation. The three-dimensional multiview estimation chain with height measurements of individual trees proved less prone to random and systematic errors than the monoscopic chain. An upper limit of accuracy at the single-tree level is determined mainly by the allometric correlations. Volume estimates of single trees showed estimation accuracies (root-mean-square error, RMSE) of 15–20% and 35–40% in the multiview and monoscopic chains, respectively. This is lower than the accuracy achievable in the field, which is 6%. Image-based single-tree forest inventory is prone to systematic measurement and model errors, and in a simulation for the total effect of error sources, upper estimation accuracies (RMSE) of 15% and 30% for stand volume were computed using full mapping of the stand with the multiview and monoscopic estimation chains, respectively.
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He-si, PAN, et LIU Hong-zhi. « The evolutionary game analysis of cross-regional ecological compensation - based on the perspective of the main functional area ». E3S Web of Conferences 53 (2018) : 04043. http://dx.doi.org/10.1051/e3sconf/20185304043.
Texte intégralRésumé :
Under the new normal, the carrying capacity of ecological environment in China has reached or approached the upper limit. The root cause is the lack of an endogenous mechanism for the protection and compensation of forest resources. Therefore, clarifying the game relationship between stakeholders can help to break through the dilemma. An evolutionary game model between beneficiary regions and the protected regions was constructed, based on the “restraint-encouragement” mechanism of the central government.The results show that in cross-regional ecological compensation, the optimal strategy of “ protectioncompensation” depend on the net profits of local governments and the central government's fines.
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Mikhailovich, Anna, et Valery Fomin. « Quantitative Assessment of Forest–Tundra Patch Dynamics in Polar Urals Due to Modern Climate Change ». Forests 14, no 12 (29 novembre 2023) : 2340. http://dx.doi.org/10.3390/f14122340.
Texte intégralRésumé :
The spatial and temporal dynamics of the Siberian larch (Larix sibirica Ledeb.) at the upper limit of its growth on the south-eastern macroslope of the Rai-Iz massif (Polar Urals, Russia) during the second half of the 20th to the beginning of the 21st century were analyzed. Current climate changes were accompanied by increased stand density on previously wooded parts of the mountain slopes and the appearance of new forest generations in lightly wooded or unforested parts of the studied area. Our original method for the automated recognition of boundaries among the key phytocoenohoras (closed forest, open forest, light forest, and tundra with single trees) is universally applicable and improves objectivity in selecting boundaries for these phytocoenohora types. With regard to the total area of the study site, the area of closed forest, open forest, and light forest, respectively, increased from 2.9% to 6.8%, from 9.6% to 13.1%, and from 7.5% to 15.6%, while the area of tundra lots with single trees decreased from 79.9% to 64.5%. Phytocoenohora type replacement in the course of the study period was characterized by a transition from forms with lower density to higher-density forms. Changes in the opposite direction were not discovered. Natural wind protection barriers for young larch tree generations included hummocks and groups of grown trees. The process of gradual tundra and forest tundra forestation then began on the leeward side of the barrier close to seed-producing trees.
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Demers, Jason D., Thomas D. Lee et James P. Barrett. « Substrate type and the distribution of sugar maple at its elevational limit in the White Mountains, New Hampshire ». Canadian Journal of Forest Research 28, no 3 (1 mars 1998) : 494–98. http://dx.doi.org/10.1139/x98-008.
Texte intégralRésumé :
The relationships between tree species distribution and substrate characteristics were examined at the upper elevational limit of sugar maple (Acer saccharum Marsh.) in the White Mountain National Forest, New Hampshire. Four tree species were studied: sugar maple, balsam fir (Abies balsamea (L.) Mill.), red spruce (Picea rubens Sarg.), and yellow birch (Betula alleghaniensis Britton). At 51 individual trees (>=2.5 cm diameter at breast height) of each species, "substrate type" was described based on the parent material, soil horizons, depth and texture of the B and C horizons, nature of surface boulders, and the depth to and type of impermeable layer. Substrate type was significantly (p < 0.001) associated with tree species. Sugar maple was relatively more frequent on deep fine and compact tills, less frequent on washed or shallow till, and absent on shallow, organic, or grus (weathered granite) substrates. Red spruce, balsam fir, and yellow birch were less sensitive to substrate type. Red spruce and yellow birch were most frequent on organic material or grus over rock. Balsam fir most frequently occurred on washed till. As the frequency of substrates favorable to sugar maple declined with elevation, it is possible that the upper elevational range limit of this species is influenced by substrate availability.
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Satria, Iman. « Portable Fire Pump To Handle Forest Fires and Densely Populated Urban Areas ». Jurnal Teknik Industri Terintegrasi 6, no 3 (31 juillet 2023) : 813–18. http://dx.doi.org/10.31004/jutin.v6i3.17340.
Texte intégralRésumé :
A portable fire pump is an innovative fire extinguisher with high mobility because this tool can be carried by the user. This tool can answer the problem of fires that often occur in areas that are difficult to reach by fire extinguishers in general, such as in forests or densely populated urban areas. This portable fire pump can be operated by utilizing water pressure from a pump that is placed near a water source and then the pressure is added by this tool to reach hotspots. Based on testing, this tool is capable of spraying water as far as 10 meters with a height of 15 meters. In terms of ergonomics and the risk of muscle injury from the user, this tool has been tested using anthropometry methods, Rapid Upper Limb Assessment (RULA), and Recommended Weight Limit (RWL) with results that can be used by users without risking muscle injury