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In the Shuklaphanta National Park (Nepal), we sampled the spatial distributions and diel activity patterns of tigers and leopards during three winter (dry) seasons. Densities of both predators were similar and rather low (≤ 3/100 km2), but total prey base was high (> 150 animals/km2). From camera trapping, 20 different tigers and leopards were identified. While leopards (9) were confined to areas along the reserve border, tigers (11) were located significantly farther inside, where the abundance of large-sized wild prey was higher and that of small-sized prey lower than closer to the border. In the inter-specific spatial overlap zones, the two species were never photographed at the same locations. Diel activity patterns did not differ. Normally, leopards avoid tigers owing to social interference. In our study, the spatial segregation was interpreted to be due to low predator-prey ratios (e.g., food not limiting for either species), with each species distributed in areas with highest densities of their preferred prey. Social interference behavior – although probably occurring – played a minor role. The concentration of leopards along the reserve border, coupled with a diet that included domestic dogs, suggest that different behavioral adaptations to anthropogenic factors might also have played a role.
Historical forests in the Southeastern Mixed Forest province of the United States have been less researched than other regions using historical tree surveys. We used 81,000 tree records from surveys during the 1800s to quantify composition of this ecological province. Upland oaks and pines comprised about 75% of all trees, with relatively equal composition. Oak composition may have comprised ≥ 45% to the northern and eastern sides of the province. Hickories were about 10% of composition and a few species were present at 1% to 2% composition. Currently, pine has increased to 49% composition; loblolly pine was 46% of all trees. Upland oaks decreased to 8% composition. Paralleling other historically oak- or pinedominated regions, fire-intolerant species increased to 40% of composition, particularly early-successional sweetgum. Historical oak-pine forests mostly have converted to loblolly pine plantations and broadleaf forests in this region. A large extent of the eastern United States historically was dominated by oak or pine forests, which likely were open old growth forests due to a frequent, low-to-moderate severity fire regime that reduced tree densities and infrequently disturbed overstory trees. Open old growth forests should be recognized as distinct ecosystems with unique characteristics, ecological functioning, and associated management practices.
Human disturbance causes behavioral responses in wildlife, including large carnivores. Previous research in Scandinavia has documented that brown bears (Ursus arctos) show a variety of behavioral reactions to different human activities. We investigated how proximity to human settlements and roads, as proxies of human influence, affected brown bears' reactions to encountering humans. We analyzed experimental approaches to GPS collared bears, 18 males and 23 single females, in Sweden (n = 148 approaches) and Finland (n = 33), conducted between 2004 and 2012. The bears in Finland inhabited areas with higher human density compared to Sweden. However, the proportion of bears staying or moving when approached and the flight initiation distances were similar in both countries. In Sweden, the flight responses were not dependent on human densities or roads inside the bears' home ranges or the distances from the bears to roads and settlements. Brown bears in Fennoscandia live in areas with relatively low human population densities, but in many areas with high forestry road densities. Our results show that bears' flight reactions were consistent between areas, which is an important message for management, reinforcing previous studies that have documented human avoidance by bears at different spatial and temporal scales.
We developed a model of hardwood tree colonization in forest patches. We began with a basic model of species' recruitment density calculated as a function of seed production and juvenile survivorship. Survivorship probability was expressed as a function of seed size, using seed-sowing data for a wide variety of species. To account for dispersal, we used an exponential distancedecay function based on empirical colonization data for species classified by dispersal mechanism and seed mass. The basic model reasonably predicted observed recruitment densities at or near forest edges, except for small seeded, wind-dispersed species with strong establishment constraints, for which it over-predicts. Our dispersal term yielded predictions that were not statistically different from observed colonization. However, species with large seeds and unspecialized dispersal mechanism appear to have distinct thresholds beyond which no dispersal occurs. Further research should better account for establishment constraints among small-seeded species, dispersal constraints among large-seeded species and unspecialized dispersers, and improve the dispersal functions to better reflect vectors such as birds. Nevertheless, the present model is adequate for the prediction of colonization probabilities in fragmented forests, requiring only an estimate of the abundance of source trees of a species and the mean inter-fragment distances.
The growth rate of most tree species in boreal forests will increase with changing climate. This increase is counterbalanced by an increased risk of damage due to extreme weather events. It is believed that the risk of storm damage will increase over time, especially if forests continue to be managed as they are today. In this study, a new landscape-level hybrid forest growth model 3PG-Heureka was developed and simulations were performed to predict the damage caused by storm events in Kronoberg county, over a period of 91 years (2010–2100) with different alternative management regimes under various climatic scenarios (historic, RCP4.5 and RCP8.5). The results indicate that damage caused by storm events could drastically reduce the annual volume increment and annual net revenue obtained from forest landscapes if current forest management regimes are used. These problems can be reduced by adopting alternative management strategies involving avoiding thinning, shorter rotation periods and planting alternative tree species. Alternative management strategies could potentially improve annual volume increments and net revenue obtained while reducing storm-felling. Planting Scots pine instead of Norway spruce across the landscape to minimize storm damage is predicted to be less effective than reducing rotation periods.
KEYWORDS: Annual average insolation, aridity index, endorheic basin, mean temperature of the warmest month, mean annual evapotranspiration, vegetation conservation
Understanding the response of vegetation to a changing global climate is important. The relationships among 33 topographic, soil and climatic variables and 74 vegetation assemblages were analyzed by detrended canonical correspondence analysis (DCCA) to determine the most important variables that affect vegetation patterns and their distribution in different reaches of the Heihe River Basin. Altitude was the most significant factor across the entire basin and in the middle reach (oasis-desert area, 1289–3920 m). Mean temperature of the warmest month and mean annual evapotranspiration were the most significant factors in the upper reach (mountain area, 2180–547 m) and the lower reach (desert area, 820–2593 m), respectively. The annual average insolation and the aridity index also had significant relationships with vegetation distribution in the mountain area. Mean temperature of the coldest month and annual cumulated temperatures ≥ 10°C also were important in the oasis-desert area, and soil organic matter and groundwater depth in the desert area. Conservation of varying tree, shrub and grass species should be considered based on their thermal and water requirements in the mountain area.
From September 2015 to February 2016, we collected field data to study the tree species diversity, population structure and regeneration potential of five sacred forests of western Odisha, India, that differ in size, associated deities, and local communities. The close association of sacred forests with local people represents a community-based, participatory approach to conservation. Our quantitative analysis in five sites documented 78 tree species of 66 genera and 33 families. Tree density and species diversity were higher than previously reported for the forests of the Eastern Ghats, India. Population structure and regeneration potential in four out of five study sites showed a higher percentage of density in the seedling and sapling layers, demon-strating that these sites are regenerating. However, in the Gugarpat sacred forest, the population structure revealed large numbers of mature trees with a stable population structure. In our study, large proportions of species had either poor regeneration potential or were not regenerating. Hence, management strategies are needed to conserve these species. Our study documents the diversity, population patterns, and regeneration of the tree species of five sacred forests, which may help in further management and conservation of the biodiversity of sacred forests in India and globally.
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