A landscape and policy perspective on forest conversion: Long-tailed tit (<Emphasis Type="Italic">Aegithalos caudatus</Emphasis>) and the allocation of deciduous forests in southern Sweden

As resources allocated specifically for conservation are limited, there is a need to ensure conservation policy initiatives lead to effective conservation outcomes. In this study, we investigated the potential conservation benefits from alternative spatial allocations of old deciduous stands to a landscape dominated by coniferous production forests owned primarily by non-industrial private forest owners. As a target species, we used the long-tailed tit (Aegithalos caudatus), a species associated with deciduous forests and known to be sensitive to isolation. We used a previously published model based on empirical data on the occurrence of this species, to assess the probability of occurrence of the bird in a 4,000 km² area in southern Sweden for which we possess detailed spatial GIS data (kNN data) of tree species composition and age. We assessed alternative scenarios where old deciduous forest was allocated with or without respect to distance from existing old deciduous forests. Due to the long-tailed tit’s habitat requirement increasing the amount of old deciduous forests close to existing habitats was the most effective strategy. However, the potential advantages of this strategy may in fact be overturned in favor of the other scenarios if ownership structures and probable uptake rates of policy initiatives are also considered. If a policy initiative is targeted toward owners with properties in close proximity to existing suitable habitat, when compared to if all forest owners are targeted, a higher proportion of owners is needed to participate in order to achieve the same degree of habitat creation for the species. Here, we discuss the potential benefits for effective conservation policy formulation from integrating spatially explicit datasets and detailed ecological knowledge with land-ownership structures and policy uptake scenarios.     

Distribution modelling of Japanese honeysuckle (Lonicera japonica) invasion in the Cumberland Plateau and Mountain Region, USA

Predicting the potential distribution of invasive plants within a specific region is pivotal to planning effective management but is challenged by attempting to model expanding populations that are rarely at equilibrium with their environment. We adopt an ensemble modelling approach to assess the potential distribution of Japanese honeysuckle (Lonicera japonica), a vine invasive to forests of the Cumberland Plateau and Mountain Region in the southeast of USA. The influence of disturbance, spatial and temporal heterogeneity and other landscape characteristics were assessed by creating regional level models based on occurrence records from the United States Department of Agriculture, Forest Service, Forest Inventory and Analysis (FIA) database. Logistic regression and maximum entropy (MaxEnt) models were assessed independently and evaluated as predictive tools to test the value of presence/absence and presence only data in predicting species distributions. Ensemble models were also developed that combined the predictions of the two modelling approaches to obtain a more robust prediction. While logistic and MaxEnt models were similar in their predictive ability and dominant input variables, the ensemble approach derived the best fitting model overall. The regional distribution of Japanese honeysuckle was influenced greatly by environmental conditions such as elevation, slope, and temperature with anthropogenic activity having significant, though lesser, influence. The ensemble models predict that Japanese honeysuckle has nearly reached its potential distribution. However, given the critical role of minimum temperature on Japanese honeysuckle distribution, future occupancy at higher elevations is likely to increase since January temperatures for this region are predicted to rise by 1-4 °C over the next 100 years. The models also give some indication of the likely effect of land cover change on its distribution. Japanese honeysuckle tended to be associated with a high component of farming or low component of forest within the local neighbourhood. This suggests disturbed forest and/or high fragmentation has a higher invasion potential and given past trends and expected continued population growth this disturbance and fragmentation will only increase. The models can be integrated into forest management decision support systems and assist in the development of long term management plans, integrating the impact of potential climate and land cover change scenarios.     

Effects of historic wildfire and prescribed fire on site occupancy of bats in Shenandoah National Park,Virginia,USA

Given the likelihood of regional extirpation of several once-common bat species in eastern North America from white-nose syndrome,it is critical that the impacts of forest management activities,such as prescribed fire,are known in order to minimize potentially additive negative effects on bat populations.Historic wildfires may offer a suitable surrogate to assess long-term burn impacts on bats for planning,implementing and assessing burn programs.To examine the effects of historic fire on bats,we sampled bat activities at 24 transect locations in burned and unburned forest stands in the central Appalachian Mountains of Shenandoah National Park(SNP),Virginia,USA.There was limited evidence of positive fire effects over time on hoary bats(Lasiurus cinereus Beauvois) and big brown bats(Eptesicus fuscus Beauvois) occupancy.Overall,there were few or mostly equivocal relationships of bat occupancy relative to burn conditions or time since fire in SNP across species using a false-positive occupancy approach.Our results suggest that fire does not strongly affect bat site occupancy short-or long-term in the central Appalachians.     

Estimating potential habitat for 134 eastern US tree species under six climate scenarios

We modeled and mapped, using the predictive data mining tool Random Forests, 134 tree species from the eastern United States for potential response to several scenarios of climate change. Each species was modeled individually to show current and potential future habitats according to two emission scenarios (high emissions on current trajectory and reasonable conservation of energy implemented) and three climate models: the Parallel Climate Model, the Hadley CM3 model, and the Geophysical Fluid Dynamics Laboratory model. Since we model potential suitable habitats of species, our results should not be interpreted as actual changes in ranges of the species. We also evaluated both emission scenarios under an “average” future climate from all three models. Climate change could have large impacts on suitable habitat for tree species in the eastern United States, especially under a high emissions trajectory. Of the 134 species, approximately 66 species would gain and 54 species would lose at least 10% of their suitable habitat under climate change. A lower emission pathway would result in lower numbers of both losers and gainers. When the mean centers, i.e. center of gravity, of current and potential future habitat are evaluated, most of the species habitat moves generally northeast, up to 800 km in the hottest scenario and highest emissions trajectory. The models suggest a retreat of the spruce-fir zone and an advance of the southern oaks and pines. In any case, our results show that species will have a lot less pressure to move their suitable habitats if we follow the path of lower emissions of greenhouse gases. The information contained in this paper, and much more, is detailed on our website: http://www.nrs.fs.fed.us/atlas.     

Responses of small mammals to clear-cutting in temperate and boreal forests of Europe: a meta-analysis and review

We analyzed the responses of small mammals to clear-cutting in temperate and boreal forests in Europe. We conducted a meta-analysis of published research on most often studied small mammal species (the striped field mouse, the yellow-necked mouse, the wood mouse, the field vole, the common vole, the bank vole, the Eurasian harvest mouse, the common shrew and the Eurasian pygmy shrew), comparing their abundance on clear-cuts and in unharvested stands. For four other species (the gray-sided vole, the Siberian flying squirrel, the Eurasian red squirrel and the hazel dormouse), we provide a qualitative review of their responses to forest harvest. Results of the meta-analysis suggest that common species of small mammals usually increase in abundance after clear-cutting or are unaffected by this disturbance. As an exception, the yellow-necked mouse declines after clear-cutting in boreal but not in temperate forest. The qualitative review suggests that the responses of more specialized (e.g., arboreal) species to forest harvest are more varied than the responses of generalist species included in the meta-analysis. For some species of small mammals (e.g., the Siberian flying squirrel), habitat loss resulting from forest harvest is a major threat.     

Can habitat prediction models contribute to the restoration and conservation of the threatened tree Abies pinsapo Boiss. in Southern Spain?

We examined the association between habitat variables and the relative impacts of topographic microclimates as a valuable tool for restoration and conservation of Abies pinsapo in southern Spain. We used presence–absence data from A. pinsapo and 79 environmental variables and biomod species distribution models to describe the current and future species habitat across the Sierra de las Nieves Natural Park (southern Spain). A. pinsapo habitat was most strongly associated with microtopographic (solar incidence) and temperature variables, indicating climate-driven changes in microhabitat use. Most of the temperature variation among the study site was attributable to topographic microclimates rather than regional temperature differences, such that differences in microhabitat associations occurred principally between north- and south-facing slopes within the same region. The current potential distribution suggests that around 8.7% (56.44 km²) of the study area is highly suitable for A. pinsapo, with 9.7% (62.84 km²) being moderately suitable. Under different global circulation models and climate change scenarios, the net decrease in suitable habitat is predicted to be 93% of the current distribution by 2040, disappearing altogether by 2099. Our findings also show a sharp reduction of potential restoration areas (1.8% of the current areas). Microclimatic variation generated by the topography offers the microclimate-driven locations of habitat suitability which could shape species’ distribution restoration actions and their responses to environmental change. The approach presented here can provide a rapid assessment of the future conservation status of other important forest tree species in Spain, improving our understanding of the vulnerability of endangered species under climate change, and can be an effective tool for biodiversity conservation, restoration, and management.

     

Assessing forest vulnerability and the potential distribution of pine beetles under current and future climate scenarios in the Interior West of the US

The aim of our study was to estimate forest vulnerability and potential distribution of three bark beetles (Curculionidae: Scolytinae) under current and projected climate conditions for 2020 and 2050. Our study focused on the mountain pine beetle (Dendroctonus ponderosae), western pine beetle (Dendroctonus brevicomis), and pine engraver (Ipspini). This study was conducted across eight states in the Interior West of the US covering approximately 2.2 million km² and encompassing about 95% of the Rocky Mountains in the contiguous US. Our analyses relied on aerial surveys of bark beetle outbreaks that occurred between 1991 and 2008. Occurrence points for each species were generated within polygons created from the aerial surveys. Current and projected climate scenarios were acquired from the WorldClim database and represented by 19 bioclimatic variables. We used Maxent modeling technique fit with occurrence points and current climate data to model potential beetle distributions and forest vulnerability. Three available climate models, each having two emission scenarios, were modeled independently and results averaged to produce two predictions for 2020 and two predictions for 2050 for each analysis. Environmental parameters defined by current climate models were then used to predict conditions under future climate scenarios, and changes in different species’ ranges were calculated. Our results suggested that the potential distribution for bark beetles under current climate conditions is extensive, which coincides with infestation trends observed in the last decade. Our results predicted that suitable habitats for the mountain pine beetle and pine engraver beetle will stabilize or decrease under future climate conditions, while habitat for the western pine beetle will continue to increase over time. The greatest increase in habitat area was for the western pine beetle, where one climate model predicted a 27% increase by 2050. In contrast, the predicted habitat of the mountain pine beetle from another climate model suggested a decrease in habitat areas as great as 46% by 2050. Generally, 2020 and 2050 models that tested the three climate scenarios independently had similar trends, though one climate scenario for the western pine beetle produced contrasting results. Ranges for all three species of bark beetles shifted considerably geographically suggesting that some host species may become more vulnerable to beetle attack in the future, while others may have a reduced risk over time.     

Additions of landscape metrics improve predictions of occurrence of species distribution models

Species distribution models are used to aid our understanding of the processes driving the spatial patterns of species’ habitats. This approach has received criticism, however, largely because it neglects landscape metrics. We examined the relative impacts of landscape predictors on the accuracy of habitat models by constructing distribution models at regional scales incorporating environmental variables (climate, topography, vegetation, and soil types) and secondary species occurrence data, and using them to predict the occurrence of 36 species in 15 forest fragments where we conducted rapid surveys. We then selected six landscape predictors at the landscape scale and ran general linear models of species presence/absence with either a single scale predictor (the probabilities of occurrence of the distribution models or landscape variables) or multiple scale predictors (distribution models + one landscape variable). Our results indicated that distribution models alone had poor predictive abilities but were improved when landscape predictors were added; the species responses were not, however, similar to the multiple scale predictors. Our study thus highlights the importance of considering landscape metrics to generate more accurate habitat suitability models.     

基于最大熵模型的气候变化情景下澳洲坚果潜在适宜生境研究

为了研究气候变化情景下澳洲坚果在云南省的潜在适宜生境,采用当前和未来2050年RCP45气候变化情景下的19个生物气候因子及最大熵模型MaxEnt进行澳洲坚果生境模型构建,并进行适宜生境等级划分及空间变化特点分析。结果表明,2050年RCP45气候变化情景下3个等级的适宜生境大体上仍然保持与当前相似的空间分布格局,即高度适宜生境主要分布在云南西南部和南部,中、低度适宜生境分布在高度适宜生境区以北及以东区域。未来气候变化引起高度和中度适宜生境面积小幅度缩减(5.6%和2.4%),低度适宜生境面积增加22.5%。气候变化同时引起高度适宜生境景观格局破碎化。未来气候变化引起的澳洲坚果在云南高、中度适宜种植区总面积略有缩减,虽幅度不大,但空间分布上发生位移,且呈现破碎化趋势,产业规划时应考虑产业生命周期内气候变化造成对适宜生境迁移的影响。     

Pinus chiapensis, a keystone species: Genetics,ecology, and conservation

We present an overview of recent studies carried out on Pinus chiapensis (Mart.) Andresen (Pinus strobus var. chiapensis Mart.) and provide management and conservation recommendations. Because of its wood quality, and being commonly used by 12 ethnic groups, this pine is an outstanding forest resource at mid-altitude humid mountains of southern Mexico and Guatemala. P. chiapensis appears to be a distinctive species, closely related with North American white pines, and a potential valuable resource for establishing breeding programs with such species. P. chiapensis is the most abundant tree species in early successional stands of the tropical montane cloud forest playing a key role in ecosystem regeneration particularly in areas managed under slash-and-burn practices. However, many natural stands of this pine are severely reduced. Molecular studies based on isozymes and DNA markers reveal low genetic diversity, the lowest compared with its closest relatives (P. ayacahuite, P. monticola and P. strobus). Heterozygosity and seed viability increase significantly with population size, and inbreeding depression appears to significantly decrease seed viability, suggesting the involvement of genetic factors on population decline. Low population size is associated with both lack of perturbation in well-preserved habitats and high deforestation rates in severely disturbed habitats. Conservation and management practices require preserving and restoring connections between suitable habitats to enhance gene flow between populations, and on careful programs that monitor and control slash-and-burn practices. Restoration practices should use seeds from as many tree sources as possible to reduce inbreeding risks. Spline climate models predict significant increases in temperature, decreases in precipitation and consequently an increase of aridity along the range of P. chiapensis. Thus, assisted migration would be needed to match present genotypes to forecasted climate changes.     

Usefulness of biophysical proxy data for modelling habitat of an endangered forest species: The white-backed woodpecker Dendrocopos leucotos

Abstract

Efficient conservation planning in managed forest landscapes requires knowledge about the location of functional habitat for specialised species. We explored the importance of different variables to predict habitat suitability for the white-backed woodpecker (Dendrocopos leucotos Bechstein), a proposed umbrella species in deciduous forest. Specifically, we tested whether biophysical proxy variables indicating management intensity and the occurrence of natural processes constituted a useful complement to traditional remotely sensed data on tree species composition and forest stand age for modelling the woodpecker's habitat. Presence–absence of the woodpecker during the study period (1986–2006) in southwestern Sweden was explained by the area of edge habitats (forest bordering water or farmland) and wetland forest, and location relative to the historical marine limit. The number of years with occurrence of the woodpecker in a territory was explained by the area of forest bordering water and wetland forest. Among traditional forest variables, the area of deciduous forest had a strong positive effect on both woodpecker presence–absence and the number of years with occurrence. The results support the hypothesis that edge habitats and forest types subject to natural processes favouring deciduous trees and dead wood creation are valuable to the woodpecker and should be prioritised in conservation planning.     

气候变化情景下河北省3个优势树种适宜分布区预测

【目的】探究河北省3个优势树种分布与气候因子的关系,并进行适宜分布区预测,以期为评估气候变化的影响及制定适宜未来气候变化的森林经营策略提供理论依据。【方法】依据河北省森林资源调查数据,选取华北落叶松、蒙古栎和油松这3个主要树种,采用ClimateAP气候模型生成当前及未来(2040—2069年和2070—2099年)与降水和温度相关的10个气候因子,利用MaxEnt生态位模型和基于3个气候变化情景(温室气体最低排放,RCP2.6;中度稳定排放,RCP4.5;高度排放,RCP8.5)的一致性预测,模拟3个树种当前和未来的潜在适宜分布区,并采取响应曲线分析主要气候因子对3个树种适宜分布区的影响。【结果】3个树种MaxEnt模型的受试者工作特征曲线下面积(AUC值)都大于0.85,具有较好的预测能力;当前3个树种主要适宜分布在燕山和太行山地区;影响3个树种分布的主导气候因子存在差异,华北落叶松主要受小于0℃年积温和湿季降水量的影响,蒙古栎则主要受最热月平均气温、Hargreaves水分亏缺和湿季降水量的影响,而最热月平均气温、湿季降水量、大于5℃年积温和年均气温是影响油松分布的主要气候因子;一致性预测表明,在2040—2069年,河北省华北落叶松分布面积明显扩大,蒙古栎分布面积变化较小,而油松分布面积显著缩小;在2070—2099年,3个树种的适宜分布面积都显著缩小,幅度均超过3%。【结论】随着气候变化,3个树种均有向高海拔地区迁移的趋势,但在经纬度方向上的分布变化不大。在未来3个树种的适宜分布区,采取人工手段(如造林)辅助树种扩散以适应气候变化,有利于提高森林生产力,构建健康稳定的森林生态系统。     

Predicting upslope expansion of sub-alpine forest in the Makalu Barun National Park,Eastern Nepal,with a hybrid cartographic model

The natural upper boundary of a forest (forest line) in mountain environments is an indicator of climate conditions. An increase in global average temperatures has resulted in an upward advance of the forest line. This advance may result in fragmentation of the alpine ecosystem and a loss of biodiversity. Therefore, it is important to identify potential areas where current forests can advance under scenarios of future climate change. I used expert knowledge and cartographic modeling to create a hybrid cartographic model considering five topographic variables to predict areas where forest line can expand in the future. The prediction accuracy of the model is around 82%. The model is able to predict areas above the current forest line that are suitable or unsuitable for future forest advance. Further inclusion of high-resolution satellite imagery and digital elevation models, as well as field-based information into the model can help to improve the model accuracy.     

Projected long-term response of Southeastern birds to forest management

Numerous studies have explored the influence of forest management on avian communities empirically, but uncertainty about causal relationships between landscape patterns and temporal dynamics of bird communities calls into question how observed historical patterns can be projected into the future, particularly to assess consequences of differing management alternatives. We used the Habplan harvest scheduler to project forest conditions under several management scenarios mapped at 5-year time steps over a 40-year time span. We used empirical models of overall avian richness, richness of selected guilds, and probability of presence for selected species to predict avian community characteristics for each of the mapped landscapes generated for each 5-year time step for each management scenario. We then used time series analyses to quantify relationships between changes in avian community characteristics and management-induced changes to forest landscapes over time. Our models of avian community and species characteristics indicated habitat associations at multiple spatial scales, although landscape-level measures of habitat were generally more important than stand-level measures. Our projections showed overall avian richness, richness of Neotropical migrants, and the presence of Blue-gray Gnatcatchers and Eastern Wood-pewees varied little among management scenarios, corresponding closely to broad, overall landscape changes over time. By contrast, richness of canopy nesters, richness of cavity nesters, richness of scrub-successional associates, and the presence of Common Yellowthroats showed high temporal variability among management scenarios, likely corresponding to short-term, fine-scale changes in the landscape. Predicted temporal variability of both interior-forest and early successional birds was low in the unharvested landscape relative to that in the harvested landscape. Our results also suggested that early successional species can be sensitive to both availability and connectivity of habitat on the landscape. To increase or maintain the avian diversity, our projections indicate that forest managers need to consider landscape-scale configuration of stands, maintaining a spatially heterogeneous distribution of age classes. Our findings suggest which measures of richness or species presence may be appropriate indicators for monitoring effects of forest management on avian communities, depending on management objectives.     

Simulating the effects of climate change on forest dynamics on Gongga Mountain,Southwest China

Forest gap models are important tools for assessing the impact of global climate change on forest dynamics of tree species composition and size structure. In this study, the FAREAST gap model was used to examine the response of forest dynamics on Gongga Mountain, which is located on the southeastern fringe of the Tibetan Plateau, under three climate change scenarios. The simulated results showed that the climax community of the deglaciation slash would be mixed species of Picea brachytyla, Tsuga chinensis, and Pinus densata under climate change scenarios, as opposed to the pure Abies fabri forest under the current climate. Climate change also drove replacement of Populus purdomiis by Betula utilis, which became the most abundant pioneer tree species on the deglaciation slash. Under scenarios of climate change, three responses of the four typical forests distributed between 2200 and 3580 m above sea level are observed, such as dieback of today’s forest at 2200 and 3150 m, gradual change of the species composition at 2780 m, and afforestation at 3580 m. It is worth noting that the scenarios of climatic change are of inherent uncertainty, in the same way as the formulation of the ecological factors used in the models. It is suggested that simulations not be interpreted as predictions of the future development of the forest, but as a means of assessing their sensitivity to climate change. It is concluded that mountainous forests are quite sensitive to climate change.     

Potential redistribution of tree species habitat under five climate change scenarios in the eastern US

Global climate change could have profound effects on the Earth’s biota, including large redistributions of tree species and forest types. We used DISTRIB, a deterministic regression tree analysis model, to examine environmental drivers related to current forest-species distributions and then model potential suitable habitat under five climate change scenarios associated with a doubling of atmospheric CO₂. Potential shifts in suitable habitat for 76 common tree species in the eastern US were evaluated based on more than 100,000 plots and 33 environmental variables related to climate, soils, land use, and elevation. Regression tree analysis was used to devise prediction rules from current species–environment relationships. These rules were used to replicate the current distribution and predict the potential suitable habitat for more than 2100 counties east of the 100th meridian. The calculation of an importance value-weighted area score, averaged across the five climate scenarios, allowed comparison among species for their overall potential to be affected by climate change. When this score was averaged across all five climate scenarios, 34 tree species were projected to expand by at least 10%, while 31 species could decrease by at least 10%. Several species (Populus tremuloides, P. grandidentata, Acer saccharum, Betula papyrifera, Thuja occidentalis) could have their suitable habitat extirpated from US. Depending on the scenario, the optimum latitude of suitable habitat moved north more than 20 km for 38–47 species, including 8–27 species more than 200 km or into Canada. Although the five scenarios were in general agreement with respect to the overall tendencies in potential future suitable habitat, significant variations occurred in the amount of potential movement in many of the species. The five scenarios were ranked for their severity on potential tree habitat changes. Actual species redistributions, within the suitable habitat modeled here, will be controlled by migration rates through fragmented landscapes, as well as human manipulations.     

Predicting Potential Density and Basal Area Development in the Social Forestry Plantations of Acacia nilotica in Gujarat State of India

ABSTRACT

Growth modelling is an important and effective tool for evaluating the effects of a particular management action on the future development of a forest ecosystem. However, such necessary growth models are not available for many indigenous tree species in India. Acacia nilotica is an important multipurpose tree species found in India and growth models are required for proper management of the species in the region. This paper presents equations for estimating potential stand density and predicting basal area in pure even-aged stands of A. nilotica in Gujarat State of India. Although no thinning was suggested, decrease in the number of trees in the stands was observed because of mortality due to overcrowding and some biotic factors. Relationships between quadratic mean diameter and stems per hectare were developed, which was used to establish the limiting density line. Eight different stand level models, belonging to the path invariant algebraic difference form of a non-linear growth function, were compared for projecting basal area. They can be used to predict future basal area as a function of stand variables like dominant height and stem number per hectare and are crucial for evaluating different silvicultural treatment options. The performance of the models was evaluated using different statistical criteria to recommend the suitable model for projecting the basal area in A. nilotica stands.     

大巴山区笋竹产业潜力与资源培植配置

川陕革命老区大巴山区拥有优良乡土竹种资源和生产绿色食品的山地立体生态环境资源优势,竹林经营类型转换是发挥区域比较优势,实现区域竹业发展的根本。山地立体生态环境是竹林类型分布和资源培植配置的主导因素,是大巴山笋竹产业发展的优势潜力。在分析大巴山区竹资源基础与笋用开发潜力的基础上,围绕周年产笋的区域基地建设进行了笋用竹资源培植配置设计,涉及11个竹种,3种培植经营模式。     

Goshawk breeding densities in relation to mature forest in southeastern Norway

Forest harvesting practices have been assumed to be the main reason for the decrease in Goshawk Accipiter gentilis populations in Fennoscandia during the late 1900s, by reducing prey density, especially grouse and Red Squirrel (Sciurus vulgaris), and preferred hunting habitats (mature forest). In Norway, the highest breeding densities are now found in areas with a high proportion of farmland and urban areas where corvids and pigeons are important prey. To assess the importance of mature forest for Goshawk populations in southeastern Norway, we compared breeding densities from 20 municipalities with different percentages of farmland and mature forest. In multiple regression models, regional breeding densities were positively related to both the percentage of mature forest, and the percentage of farmland and urban areas. We conclude that the recommendation of establishing buffer zones around nest sites will not be sufficient to maintain Goshawk populations if the proportion of mature forest is reduced at a landscape level.