Probability distributions,vulnerability and sensitivity in Fagus crenata forests following predicted climate changes in Japan

Question: How much is the probability distribution of Fagus crenata forests predicted to change under a climate change scenario by the 2090s, and what are the potential impacts on these forests? What are the main factors inducing such changes? Location: The major islands of Japan. Methods: A predictive distribution model was developed with four climatic factors (summer precipitation, PRS; winter precipitation, PRW; minimum temperature of the coldest month, TMC; and warmth index, WI) and five non‐climatic factors (topography, surface geology, soil, slope aspect and inclination). A climate change scenario was applied to the model. Results: Areas with high probability (> 0.5) were predicted to decrease by 91%, retreating from the southwest, shrinking in central regions, and expanding northeastwards beyond their current northern limits. A vulnerability index (the reciprocal of the predicted probability) suggests that Kyushu, Shikoku, the Pacific Ocean side of Honshu and southwest Hokkaido will have high numbers of many vulnerable F. crenata forests. The forests with high negative sensitivity indices (the difference between simulated probabilities of occurrence under current and predicted climates) mainly occur in southwest Hokkaido and the Sea of Japan side of northern Honshu. Conclusion: F. crenata forest distributions may retreat from some islands due to a high WI. The predicted northeastward shift in northern Hokkaido is associated with increased TMC and PRS. High vulnerability and negative sensitivity of the forests in southern Hokkaido are due to increased WI.     

Assessing the impact of land use and climate change on the evergreen broad-leaved species of <Emphasis Type="Italic">Quercus acuta</Emphasis> in Japan

To assess the impact of Quercus acuta, a dominant species in the evergreen broad-leaved forests of Japan, and its habitat shifts as a result of climate change, we predicted the potential habitats under the current climate and two climate change scenarios using a random forest (RF). The presence/absence records of Q. acuta were extracted from the Phytosociological Relevè Data Base as response variables, and four climatic variables (warmth index, WI; minimum temperature of the coldest month, TMC; summer precipitation, PRS; and winter precipitation, PRW) were used as predictor variables. The mean decrease in the Gini criterion revealed that WI was the most influential factor followed by TMC. The RF revealed a considerable increase in potential habitats (PHs) under the climate change scenarios for 2081–2100 (RCM20, 180,141 km²; MIROC, 175,635 km²) relative to the current climate (150,542 km²). The land use variables were used for masking PH. The PH masked by land use (PHLU) was approximately half of the PH under the current conditions (74,567 km²). Under the climate change scenarios and 1 km migration options, the PHLU were not increased relative to its value under the current conditions. The distribution of Q. acuta was restricted by the northward shift in northern Honshu, but expanded as a result of the upward shift into the mountain areas of Western Japan. Habitat fragmentation reduced the ability of migration to respond to climate change in the lowland areas of Japan.     

Climatic limits for the present distribution of beech (Fagus L.) species in the world

Aim Beech (Fagus L., Fagaceae) species are representative trees of temperate deciduous broadleaf forests in the Northern Hemisphere. We focus on the distributional limits of beech species, in particular on identifying climatic factors associated with their present range limits. Location Beech species occur in East Asia, Europe and West Asia, and North America. We collated information on both the southern and northern range limits and the lower and upper elevational limits for beech species in each region. Methods In total, 292 lower/southern limit and 310 upper/northern limit sites with available climatic data for all 11 extant beech species were collected by reviewing the literature, and 13 climatic variables were estimated for each site from climate normals at nearby stations. We used principal components analysis (PCA) to detect climatic variables most strongly associated with the distribution of beech species and to compare the climatic spaces for the different beech species. Results Statistics for thermal and moisture climatic conditions at the lower/southern and upper/northern limits of all world beech species are presented. The first two PCA components accounted for 70% and 68% of the overall variance in lower/southern and upper/northern range limits, respectively. The first PCA axis represented a thermal gradient, and the second a moisture gradient associated with the world‐wide distribution pattern of beech species. Among thermal variables, growing season warmth was most important for beech distribution, but winter low temperature (coldness and mean temperature for the coldest month) and climatic continentality were also coupled with beech occurrence. The moisture gradient, indicated by precipitation and moisture indices, showed regional differences. American beech had the widest thermal range, Japanese beeches the most narrow; European beeches occurred in the driest climate, Japanese beeches the most humid. Climatic spaces for Chinese beech species were between those of American and European species. Main conclusions The distributional limits of beech species were primarily associated with thermal factors, but moisture regime also played a role. There were some regional differences in the climatic correlates of distribution. The growing season temperature regime was most important in explaining distribution of Chinese beeches, whilst their northward distribution was mainly limited by shortage of precipitation. In Japan, distribution limits of beech species were correlated with summer temperature, but the local dominance of beech was likely to be dependent on snowfall and winter low temperature. High summer temperature was probably a limiting factor for southward extension of American beech, while growing season warmth seemed critical for its northward distribution. Although the present distribution of beech species corresponded well to the contemporary climate in most areas, climatic factors could not account for some distributions, e. g., that of F. mexicana compared to its close relative F. grandifolia. It is likely that historical factors play a secondary role in determining the present distribution of beech species. The lack of F. grandifolia on the island of Newfoundland, Canada, may be due to inadequate growing season warmth. Similarly, the northerly distribution of beech in Britain has not reached its potential limit, perhaps due to insufficient time since deglaciation to expand its range.     

Diversity of forest vegetation across a strong gradient of climatic continentality: Western Sayan Mountains, southern Siberia

Southern Siberian mountain ranges encompass strong climatic contrasts from the relatively oceanic northern foothills to strongly continental intermountain basins in the south. Landscape-scale climatic differences create vegetation patterns, which are analogous to the broad-scale vegetation zonation over large areas of northern Eurasia. In their southern, continental areas, these mountains harbour forest types which potentially resemble the full-glacial forests recently reconstructed for Central Europe. To identify forest vegetation–environment relationships in the southern Siberian mountain ranges, forest vegetation of the Western Sayan Mountains was sampled on a 280 km transect running from the northern foothills with oceanic climatic features to the continental Central Tuvinian Basin in the south. Based on the species composition, vegetation was classified into hemiboreal forests, occurring at drier and summer-warm sites with high-pH soil, and taiga, occurring at wetter, summer-cool sites with acidic soil. Hemiboreal forests included Betula pendula-Pinus sylvestris mesic forest, Larix sibirica dry forest and Pinus sylvestris dry forest. Taiga included Abies sibirica-Betula pendula wet forest, Abies sibirica-Pinus sibirica mesic forest and Pinus sibirica-Picea obovata continental forest. Hemiboreal forests were richer in vascular plant species, while taiga was richer in ground-dwelling cryptogams. Vegetation–environment relationships were analysed by indirect and direct ordination. Winter and summer temperatures and precipitation exerted a dominant influence on species composition. Soil pH was also an important correlate of species composition, but this factor itself was probably controlled by precipitation. At a more local scale, the main source of variation in species composition was topography, producing landscape patterns of contrasting plant communities on slopes of different aspects and valley bottoms. The response of tree species to major environmental factors was expressed with Huisman–Olff–Fresco models. Larix sibirica appeared to be most resistant to drought and winter frosts, Pinus sibirica was adapted to low temperatures both in winter and summer, and Picea obovata had an intermediate response to climate. Betula pendula, Pinus sylvestris and Populus tremula were associated with the warmest sites with intermediate precipitation, while Abies sibirica was the most moisture-demanding species, sensitive to deep winter frosts.     

On the distributional limits of the lucidophyllous forest in the Japanese Archipelago

The distribution of the lucidophyllous forest and its transition to the summergreen broadleaf forest were studied in relation to such environmental factors as temperature and precipitation. The distribution is primarily affected by low temperatures during winter and secondarily by precipitation and sea wind. The upper and northern limits of the forest most closely correlated with the coldness index within four thermal indices. Because of much snow, the forest is more suppressed at a lower altitude in the region with high snowfall than in other regions. The area at its upper limit is dominated by the evergreenQuercus forest while the area at its northern limit is occupied by thePersea forest. Moreover, CI values in these distributional limits are significantly different. This phenomenon appeared to result from the resistance ability of dominant lucidophyllous trees not only to the thermal conditions but also to sea wind. In both the region with high snowfall and the region with high rainfall there is a zone where the evergreenQuercus forest overlaps theFagus crenata forest. In contrast, in the region with little rainfall, these two forests do not overlap but form a gap dominated by forests such as theFagus japonica forest. Thus, precipitation factors largely affect the altitudinal forest zones in Japan.     

Forecasting the potential distribution of Spodoptera exigua and S. littoralis (Lepidoptera,Noctuidae) in Iran

The beet armyworm, Spodoptera exigua (Hübner, 1808) and the Egyptian cotton leafworm, S. littoralis (Boisduval, 1833), are amongst the most notorious agricultural pest species in Iran. Spodoptera exigua is considered a serious pest of different crops, whereas S. littoralis is known as an important pest of cotton.In this paper, the potential distribution areas of these species in Iran and the important climatic factors affecting their distribution were predicted using the MaxEnt model and the ArcGIS. The results indicate that the main environmental variables contributing to S. exigua’s distribution were precipitation of the coldest quarter (bio19), average wind speed in April (wind4), and annual precipitation (bio12). Also, minimum temperature of the coldest month (bio6), mean temperature of coldest quarter (bio11), altitude and average wind speed in May (wind5) were dominant climatic factors that affected the potential distribution of S. littoralis. These species overlapped in most parts of coastal areas in the southern and northern parts of Iran, with an average overlapping range of 33.2%. Considering their preferred host plants in Iran, it is necessary to strengthen biosurveillance programes and management of these two species in their suitable areas to prevent further invasion, which endangers agricultural security.     

Shifts in potential geographical distribution of Pterocarya stenoptera under climate change scenarios in China

Climate change poses a serious threat to biodiversity. Predicting the effects of climate change on the distribution of a species' habitat can help humans address the potential threats which may change the scope and distribution of species. Pterocarya stenoptera is a common fast‐growing tree species often used in the ecological restoration of riverbanks and alpine forests in central and eastern China. Until now, the characteristics of the distribution of this species' habitat are poorly known as are the environmental factors that influence its preferred habitat. In the present study, the Maximum Entropy Modeling (Maxent) algorithm and the Genetic Algorithm for Ruleset Production (GARP) were used to establish the models for the potential distribution of this species by selecting 236 sites with known occurrences and 14 environmental variables. The results indicate that both models have good predictive power. Minimum temperature of coldest month (Bio6), mean temperature of warmest quarter (Bio10), annual precipitation (Bio12), and precipitation of driest month (Bio14) were important environmental variables influencing the prediction of the Maxent model. According to the models, the temperate and subtropical regions of eastern China had high environmental suitability for this species, where the species had been recorded. Under each climate change scenario, climatic suitability of the existing range of this species increased, and its climatic niche expanded geographically to the north and higher elevation. GARP predicted a more conservative expansion. The projected spatial and temporal patterns of P. stenoptera can provide reference for the development of forest management and protection strategies.     

Geographical distribution ofSporidesmium goidanichii in pine forests of Japan

The geographical distribution of a saprotrophic hyphomycete,Sporidesmium goidanichii was studied in pine forests of Japan. Using the data of 282 fungal communitles of pine leaf litter collected over a wide range of climatic conditions, the relationships among two indexes of distribution of the species (constancy and abundance) and three climatic variables were analyzed by the multiple regression analysis. The results demonstrated that the mean annual air temperature and the mean annual range (the difference in monthly mean air temperatures between the coldest and warmest months at the study sites) were necessary variables for the prediction of the values of indexes ofS. goidanichii in pine forests of Japan, while the mean annual precipitation was an unimportant factor. The distribution patterns of the fungus along the gradients of two temperature variables were analyzed graphically. The fungus has an optimal climatic area with high values of indexes where is restricted to the center of the warm temperate regions of the main islands. The relationship between the life strategy of the fungus and its temperature-dependent distribution pattern in Japan was also discussed. Contributions to Sugadaira Montane Research Center No. 179.     

Geographical and climatic gradients of evergreen versus deciduous broad‐leaved tree species in subtropical China: Implications for the definition of the mixed forest

Understanding climatic influences on the proportion of evergreen versus deciduous broad‐leaved tree species in forests is of crucial importance when predicting the impact of climate change on broad‐leaved forests. Here, we quantified the geographical distribution of evergreen versus deciduous broad‐leaved tree species in subtropical China. The Relative Importance Value index (RIV ) was used to examine regional patterns in tree species dominance and was related to three key climatic variables: mean annual temperature (MAT ), minimum temperature of the coldest month (MinT), and mean annual precipitation (MAP ). We found the RIV of evergreen species to decrease with latitude at a lapse rate of 10% per degree between 23.5 and 25°N, 1% per degree at 25–29.1°N, and 15% per degree at 29.1–34°N. The RIV of evergreen species increased with: MinT at a lapse rate of 10% per °C between ?4.5 and 2.5°C and 2% per °C at 2.5–10.5°C; MAP at a lapse rate of 10% per 100 mm between 900 and 1,600 mm and 4% per 100 mm between 1,600 and 2,250 mm. All selected climatic variables cumulatively explained 71% of the geographical variation in dominance of evergreen and deciduous broad‐leaved tree species and the climatic variables, ranked in order of decreasing effects were as follows: MinT > MAP  > MAT . We further proposed that the latitudinal limit of evergreen and deciduous broad‐leaved mixed forests was 29.1–32°N, corresponding with MAT of 11–18.1°C, MinT of ?2.5 to 2.51°C, and MAP of 1,000–1,630 mm. This study is the first quantitative assessment of climatic correlates with the evergreenness and deciduousness of broad‐leaved forests in subtropical China and underscores that extreme cold temperature is the most important climatic determinant of evergreen and deciduous broad‐leaved tree species’ distributions, a finding that confirms earlier qualitative studies. Our findings also offer new insight into the definition and distribution of the mixed forest and an accurate assessment of vulnerability of mixed forests to future climate change.     

印度块菌在未来气候变化情景下的空间分布模式——以云南省为例

以印度块菌（Tuber indicum）丰产区云南省为例,利用地理信息系统和物种分布模型,并通过影响印度块菌分布的主要环境因子和气候因子,共同模拟现在及未来生境分布模式。结果表明结合环境因子和气候因子,在建模过程中能提高模型预测准确度,在几类物种分布模型中,MAXENT模型具有最优的拟合效果。在大的空间尺度上,年降水,最湿季度降水,最冷月份最低温、地貌类型及土壤类型对印度块菌的生境分布影响最大。此外,在模型模拟的A2和B2未来气候变化情景下,印度块菌未来的新增生境均呈北上趋势,且B2情景下生境的适生程度低于A2情景。     

基于最大熵模型的狸尾豆属植物在中国的潜在分布区模拟

基于19个气候因子和203条狸尾豆属（Uraria）植物地理分布记录，采用最大熵模型（MaxEnt）对植物当前分布点的气候变量进行分析，推断其在末次盛冰期（LGM）、当前和未来气候（2070s）情景下的潜在分布；采用受试者工作曲线和刀切法对模型的准确性进行检验并探明影响该属在中国分布的气候因子。结果显示：最大熵模型模拟结果极准确，测试集和训练集假阳性值（AUC）分别达到0.934和0.936；影响该属植物分布的主要气候因子是最暖季节降水和最冷月份最低温度；广西、广东及台湾地区为该属在中国的起源中心。在全球气候变暖背景下，狸尾豆属植物的适生环境将向中国北部及东部沿海地区推移，且面积逐渐增加。     

Ecological response surfaces for North American boreal tree species and their use in forest classification

Abstract. Empirical ecological response surfaces were derived for eight dominant tree species in the boreal forest region of Canada. Stepwise logistic regression was used to model species dominance as a response to five climatic predictor variables. The predictor variables (annual snowfall, degree-days, absolute minimum temperature, annual soil moisture deficit, and actual evapotranspiration summed over the summer months) influence the response of plants more directly than the annual or monthly measures of temperature and precipitation commonly used in response surface modeling. The response surfaces provided estimates of the probability of species dominance across the spatial extent of North America with a high degree of success. Much of the variation in the probability of dominance is apparently related to the species' individualistic response to climatic constraints within different airmass regions. A forest type classification for the Canadian boreal forest region was derived by a cluster analysis based on the probability estimates. Five major forest types were distinguished by the application of a stopping rule. The predicted forest types showed a high degree of geographic correspondence with the distribution of forest types in the actual vegetation mosaic. The distribution of the predicted types also bears a direct relationship to seasonal airmass dynamics in the boreal forest region.     

Regeneration dynamics, causal factors, and characteristics of pacific ocean-type beech (Fagus crenata) forests in Japan: A review

This paper reviews the differences in the distribution and regeneration ofFagus crenata between two types of Japanese beech forests, the Japan Sea (JS)-type and the Pacific Ocean (PO)-type, and discusses the causal factors and characteristics of these forests, particularly the PO-type.F. crenata in PO-type forests regenerates sporadically rather than constantly, whereas regeneration in the JS-type forests is relatively constant with gap dynamics.F. crenata has dominated in snowy areas both in the past, after the last glacial age, when there was less human disturbance, and in the present. Snow accumulation facilitates beech regeneration in snowy JS-type forests, but not in the less snowy PO-type. Snow protects beechnuts from damage caused by rodents, desiccation, and freezing. In addition, snow suppresses dwarf bamboo in the spring, thus increasing the amount of sunlight available for beech seedlings on the forest floor. Snow also supplies melt water during the growing season and limits the distribution of herbivores. Moreover, snow reduces the number of forest fires during the dry winter and early spring seasons. The low densities ofF. crenata impede its regeneration, because disturbed wind pollination lowers seed fertility and predators are less effectively satiated. In snowy JS-type beech forests,F. crenata dominates both at the adult and the juvenile stages because it regenerates well, while other species are eliminated by heavy snow pressure. On the less snowy PO-side, deciduous broad-leaved forests with various species are a primary feature, althoughF. crenata dominates because of its large size and long lifespan.     

Composition,dynamics and disturbance regime of temperate deciduous forests in Monsoon Asia

Temperate deciduous forests in Monsoon Asia are classified into three forest types which differ in floristic composition, dynamics and disturbance regime. The cool temperate mixed deciduous broadleaf/conifer forest, dominated by Quercus spp. (mainly Q. mongolica or Q. crispula) and conifers, is distributed in northern parts of the temperate zone. The cool temperate deciduous forest, dominated by Fagus crenata, is distributed in Honshu, Japan under a humid climate through the year. The warm temperate deciduous forest dominated by Quercus spp. (mainly Q. acutissima or Q. serrata) occurs in the continental areas, the Korean Peninsula, and the Pacific Ocean side of Japan. The species diversity of cool temperate deciduous forest was lower than the other two types because of the intensive dominance of Fagus crenata. The disturbance regimes also varies among the three types; small scale treefall gaps are prevailing in the cool temperate deciduous forest, while larger scaled disturbances are important in the other two forest types. Fire seems to be important in the warm temperate deciduous forest, and both fire and large scale blowdowm seems important in the cool temperate mixed broadleaf/conifer forest. These differences in forest composition and disturbance regimes associated with climatic conditions and ancient human impacts have a close analogy with the Northeastern Hardwood forests in North America.     

Spatial variation and temporal instability in climate-growth relationships of sessile oak (<Emphasis Type="Italic">Quercus petraea</Emphasis> [Matt.] Liebl.) under temperate conditions

Temporal instability of forest climate-growth relationships has been evidenced at high elevations and latitudes, and in Mediterranean contexts. Investigations under temperate conditions, where growth is under the control of both winter frost and summer water stress, are scarce and could provide valuable information about the ability of forest to cope with climate change. To highlight the main climatic factors driving the radial growth of Quercus petraea forests and to detect their possible evolutions over the last century, dendroecological analyses were performed along a longitudinal gradient of both decreasing summer water stress and increasing winter frost in northern France (from oceanic to semi-continental conditions). The climate-growth relationships were evaluated from 31 tree-ring chronologies (720 trees) through the calculation of moving correlation functions. Q. petraea displayed a rather low sensitivity to climate. High temperature in March and water stress from May to July appeared to be the main growth limiting factors. The sensitivity to winter precipitation and summer water stress decreased from oceanic to semi-continental conditions, whilst the correlation to winter frost tended to increase. Moving correlations revealed a general instability of climate-growth relationships, with a moderate synchronicity with climatic fluctuations. The main changes occurred during previous autumn for both temperature and precipitation whilst climatic trends were rather low or non-significant. The most coherent trends were pointed out (i) in April with a cooling (−0.9°C) leading to positive correlation to temperature at the end of the century, and (ii) in July with a decreasing inter-annual variability of precipitation resulting in a loss of correlation. On the contrary, the decreasing temperature and increasing precipitation in May and June led to few significant changes climate-growth relationships.     

Climate and vegetation in China V. Effect of climatic factors on the upper limit of distribution of evergreen broadleaf forest

In order to clarify correlations between the upper limit of distribution of evergreen broadleaf forest and climatic factors, 62 stands distributed at the upper limit of the forest were collected from various parts of China, and their thermal and precipitation factors were estimated. Among six thermal climatic indices, i.e., warmth index (WI), coldness index (CI) and annual mean (AMT), January mean (JMT), mean minimum (MMT) and minimum (MT) temperatures, the CI at the stands showed the smallest range of variance, and it was therefore considered to be the most significant for interpreting the upward distribution of the forest. However, the distribution of the forest in mountain areas in southwestern China could not be explained by lower temperatures in winter such as CI but by a cumulative temperature such as WI. The continentality and precipitation factors were also important for delimiting the distribution of the forest. In addition, the relation between the distribution of the forest and the MMT was noted, and it was concluded that the MMT was an effective thermal index for explaining the upper limit of distribution of evergreen broadleaf forest in China.     

Predicting the distribution of shrub species in southern California from climate and terrain-derived variables

Abstract. Generalized additive, generalized linear, and classification tree models were developed to predict the distribution of 20 species of chaparral and coastal sage shrubs within the southwest ecoregion of California. Mapped explanatory variables included bioclimatic attributes related to primary environmental regimes: averages of annual precipitation, minimum temperature of the coldest month, maximum temperature of the warmest month, and topographically-distributed potential solar insolation of the wettest quarter (winter) and of the growing season (spring). Also tested for significance were slope angle (related to soil depth) and the geographic coordinates of each observation. Models were parameterized and evaluated based on species presence/absence data from 906 plots surveyed on National Forest lands. Although all variables were significant in at least one of the species’ models, those models based only on the bioclimatic variables predicted species presence with 3–26% error. While error would undoubtedly be greater if the models were evaluated using independent data, results indicate that these models are useful for predictive mapping – for interpolating species distribution data within the ecoregion. All three methods produced models with similar accuracy for a given species; GAMs were useful for exploring the shape of the response functions, GLMs allowed those response functions to be parameterized and their significance tested, and classification trees, while some-times difficult to interpret, yielded the lowest prediction errors (lower by 3–5%).     

全球气候变化下贵州省青冈林的潜在生境动态

为了解贵州省青冈林在全球气候变化下的潜在分布特征,基于现状分布数据,结合当前气候数据和未来气候变化情景(RCP8.5情景,2070-2099年)构建Maxent潜在分布模型,预测贵州省青冈林的潜在分布变化。结果表明,最冷季均温(bio11)、最冷月最低温度(bio6)和年均降水量(bio12)为控制贵州省青冈林潜在生境的主导气候因子;RCP8.5情景下贵州省青冈林的潜在分布面积相较当前气候条件增加,中度适宜生境增加19 419 km2,高度适宜生境增加9 944 km2;中度适宜生境平均海拔较当前气候条件上升126 m,高度适宜生境平均上升85 m。总的来说,贵州省青冈林对全球气候变化的响应不十分敏感。     

Influence of climate on Bonelli's eagle's (Hieraaetus fasciatus V. 1822) breeding success through the Western Mediterranean

Aim To assess the impact of certain climatic variables on the breeding success of some populations of Bonelli's eagle (Hieraaetus fasciatus V. 1822) throughout its latitudinal distribution range, in order to account for recent and differential declines in populations. Location Western Mediterranean, from southern Morocco to southern France. Methods Seven populations were considered for the latitudinal distribution range of the species. Data from 1052 breeding attempts were taken from the literature and, for each population, breeding success was measured as the mean number of fledglings per pair per year. Breeding success, as a dependent variable, was related to five geographical and climatic variables (latitude, mean annual temperature, mean minimum temperature of the coldest month, mean maximum temperature of the hottest month and mean annual precipitation) as independent variables, through some regression models, which take into account the multicolinearity of the variables. Results All the analyses agreed that average annual temperature was an important factor associated with the breeding success of the species in each region, and accounted for up to 97% of the variance of the breeding success throughout a latitudinal gradient in the study area. Main conclusions The low breeding success of the northern populations (probably because of climatic constraints) and the tendency of juveniles to disperse southwards, diminishes recruitment in those populations. Therefore, as human pressure and habitat destruction causes high adult and pre‐adult mortality of the species throughout its entire latitudinal range, disturbances in the northern populations have more profound effects, thereby explaining observed population declines.