Predicting occurrence of wolf territories in Scandinavia

We used logistic regression to compare a set of habitat features inside known Scandinavian wolf Canis lupus territories with the same habitat features in areas outside known territories, but still close enough to be available for wolf colonization. In addition, we analysed changes in habitat variables over time within wolf territories. Wolf territories had lower densities of roads, built-up areas and open land than areas outside wolf territories, but there was no difference in the density of the wolves' main prey, elk Alces alces . The logistic regression model classified 79% of Scandinavia outside the reindeer husbandry area as suitable wolf habitat, that is with a probability of wolf occurrence >0.5. The proportion of built-up areas within the wolf territory decreased as the 'borders' of the wolf territory changed over time. Our model had a reasonably high predictive power, with correct classification in 90% (18 of 20) of the observed wolf territories in the study area. Polygons, randomly distributed outside the observed wolf territories, were correctly classified as not being occupied by wolves in 85% of the cases (17 of 20). This allows a more effective use of resources to, for example, prevent wolf depredation on livestock and dogs.     

Predicting bycatch hotspots for endangered leatherback turtles on longlines in the Pacific Ocean

Fisheries bycatch is a critical source of mortality for rapidly declining populations of leatherback turtles, Dermochelys coriacea. We integrated use-intensity distributions for 135 satellite-tracked adult turtles with longline fishing effort to estimate predicted bycatch risk over space and time in the Pacific Ocean. Areas of predicted bycatch risk did not overlap for eastern and western Pacific nesting populations, warranting their consideration as distinct management units with respect to fisheries bycatch. For western Pacific nesting populations, we identified several areas of high risk in the north and central Pacific, but greatest risk was adjacent to primary nesting beaches in tropical seas of Indo-Pacific islands, largely confined to several exclusive economic zones under the jurisdiction of national authorities. For eastern Pacific nesting populations, we identified moderate risk associated with migrations to nesting beaches, but the greatest risk was in the South Pacific Gyre, a broad pelagic zone outside national waters where management is currently lacking and may prove difficult to implement. Efforts should focus on these predicted hotspots to develop more targeted management approaches to alleviate leatherback bycatch.     

流域生态系统服务热点与冷点时空格局特征

生态系统服务热冷点的识别及其空间格局特征研究对生态保护规划有着重要的意义。目前有关生态系统服务热冷点的识别多采用直接分类法,缺乏对空间关系特征的综合研究。以延河流域为例,综合集成多源数据来模拟4种生态系统服务(土壤保持、植被碳固定、产水、洪水调节)的热点与冷点时空格局变化特征。主要结论为:(1)2001—2012年,延河流域土壤保持服务在流域下游高于上游,中游地区增长较快。植被碳固定服务和洪水调节服务在流域南部地区较强,且在中下游呈上升趋势。产水服务呈现"南北低、中间高"的分布格局,在流域上游呈下降趋势,在中下游呈上升趋势。(2)生态系统服务热点主要分布在延河中下游南部地区,冷点主要分布在延河上游地区。延河中下游南部地区4种生态系统服务均较强。生态系统服务保护效率最高的是延河上游。(3)延河流域林地的土壤保持服务、植被碳固定服务和洪水调节服务均强于其他土地利用类型,而产水服务较弱,湿地则相反。草地的土壤保持服务和植被碳固定服务相对较强。耕地的4种服务强于裸露地,裸露地的4种服务均较弱。湿地的土壤保持服务、植被碳固定服务和洪水调节服务保护效率最高,林地的产水服务保护效率最高。研究结果以期为流域生态系统服务保护与恢复决策提供理论支撑。     

Predicting the time of occurrence of decompression sickness.

Probabilistic models and maximum likelihood estimation have been used to predict the occurrence of decompression sickness (DCS). We indicate a means of extending the maximum likelihood parameter estimation procedure to make use of knowledge of the time at which DCS occurs. Two models were compared in fitting a data set of nearly 1,000 exposures, in which greater than 50 cases of DCS have known times of symptom onset. The additional information provided by the time at which DCS occurred gave us better estimates of model parameters. It was also possible to discriminate between good models, which predict both the occurrence of DCS and the time at which symptoms occur, and poorer models, which may predict only the overall occurrence. The refined models may be useful in new applications for customizing decompression strategies during complex dives involving various times at several different depths. Conditional probabilities of DCS for such dives may be reckoned as the dive is taking place and the decompression strategy adjusted to circumstance. Some of the mechanistic implications and the assumptions needed for safe application of decompression strategies on the basis of conditional probabilities are discussed.     

Grasses and browsers reinforce landscape heterogeneity by excluding trees from ecosystem hotspots

Spatial heterogeneity in woody cover affects biodiversity and ecosystem function, and may be particularly influential in savanna ecosystems. Browsing and interactions with herbaceous plants can create and maintain heterogeneity in woody cover, but the relative importance of these drivers remains unclear, especially when considered across multiple edaphic contexts. In African savannas, abandoned temporary livestock corrals (bomas) develop into long-term, nutrient-rich ecosystem hotspots with unique vegetation. In central Kenya, abandoned corral sites persist for decades as treeless ‘glades’ in a wooded matrix. Though glades are treeless, areas between adjacent glades have higher tree densities than the background savanna or areas near isolated glades. The mechanisms maintaining these distinctive woody cover patterns remain unclear. We asked whether browsing or interactions with herbaceous plants help to maintain landscape heterogeneity by differentially impacting young trees in different locations. We planted the mono-dominant tree species (Acacia drepanolobium) in four locations: inside glades, far from glades, at edges of isolated glades and at edges between adjacent glades. Within each location, we assessed the separate and combined effects of herbivore exclusion (caging) and herbaceous plant removal (clearing) on tree survival and growth. Both caging and clearing improved tree survival and growth inside glades. When herbaceous plants were removed, trees inside glades grew more than trees in other locations, suggesting that glade soils were favorable for tree growth. Different types of glade edges (isolated vs. non-isolated) did not have significantly different impacts on tree performance. This represents one of the first field-based experiments testing the separate and interactive effects of browsing, grass competition and edaphic context on savanna tree performance. Our findings suggest that, by excluding trees from otherwise favorable sites, both herbaceous plants and herbivores help to maintain functionally important landscape heterogeneity in African savannas.     

海洋生态系统服务价值研究热点及主题演化——基于文献计量研究

海洋生态系统能够为人类供应食品、调节环境、提供文化支持,研究其服务价值对实现可持续发展具有重大意义。基于Web of Science核心合集数据库,利用R语言及VOSviewer计量可视化工具,对1995-2021年间海洋生态系统服务价值研究进展进行全面分析,结果表明:该领域在全球范围内受到广泛关注,自2008年起发文量呈指数式增长,美国具有绝对领先地位。相关研究发表在Ecosystem Services、Ecological Economics、Journal of Environmental Management及Science of the Total Environment等高水平期刊。研究主要集中于全球变化下海洋生态系统服务的动态变化、海洋生态系统服务价值分类及其量化、海洋生态系统服务价值评估及其应用。各研究主题之间紧密联系,经过多阶段发展,最终形成ecosystem services、management、restoration等三个主要方向。梳理了海洋生态系统服务价值领域研究现状、研究热点及演化趋势,为后续研究提供参考。     

应用马尔科夫链模型对草地螟发生程度的预测

草地螟Loxostege stictialis L.是我国北方农牧业生产上一种重要迁飞性、暴发性害虫,一旦暴发会给当地农牧生产造成严重危害.根据康保县1977-2008年1代草地螟幼虫发生程度的时间序列资料,应用马尔科夫链的转移概率预测法,构建了1～3阶转移概率矩阵,组建模型对该县2009-2011年1代草地螟发生程度进行了预测,结果与大田实际发生情况完全一致,准确率100％.对1980-2011年的历史资料进行回检,历史符合率89.9％,该方法可对草地螟进行长期预报,为草地螟长期预报提供了一种准确有效的方法,对草地螟发生程度的长期预报具有重要指导意义.     

Predicting physiognomic vegetation types with climate variables

A quantitative terrestrial vegetation model was produced which consists of:

1. A world classification of important terrestrial plant growth forms (life forms);
2. A set of predictive variables representing the main climatic correlates of these forms; and
3. Empirically obtained hypothetical limiting values defining an ecoclimatic envelope for each plant form (relative to the climatic variables).

The model was applied to a world climatic data-base (1 225 sites) in order to substantiate the hypothesized life-form status of the plant types by accurately predicting their actual world distributions. Particular combinations of forms are interpreted as vegetation formation types by reference to growth-form dominance considerations. Model validation was attempted by comparing predicted and actually occurring vegetation at independent sites on all continents. Prediction accuracy of 85% for individual plant types and 50% for vegetation structure (exact combination of actually occurring dominant forms) suggests that general macroclimatic conditions are much more important than any other factors (such as complex specific interactions) in determining general ecological structure on most sites.     

Predicting ecosystem stability from community composition and biodiversity

As biodiversity is declining at an unprecedented rate, an important current scientific challenge is to understand and predict the consequences of biodiversity loss. Here, we develop a theory that predicts the temporal variability of community biomass from the properties of individual component species in monoculture. Our theory shows that biodiversity stabilises ecosystems through three main mechanisms: (1) asynchrony in species’ responses to environmental fluctuations, (2) reduced demographic stochasticity due to overyielding in species mixtures and (3) reduced observation error (including spatial and sampling variability). Parameterised with empirical data from four long‐term grassland biodiversity experiments, our prediction explained 22–75% of the observed variability, and captured much of the effect of species richness. Richness stabilised communities mainly by increasing community biomass and reducing the strength of demographic stochasticity. Our approach calls for a re‐evaluation of the mechanisms explaining the effects of biodiversity on ecosystem stability.     

Predicting coral bleaching hotspots: the role of regional variability in thermal stress and potential adaptation rates

Sea surface temperature fields (1870–2100) forced by CO₂-induced climate change under the IPCC SRES A1B CO₂ scenario, from three World Climate Research Programme Coupled Model Intercomparison Project Phase 3 (WCRP CMIP3) models (CCSM3, CSIRO MK 3.5, and GFDL CM 2.1), were used to examine how coral sensitivity to thermal stress and rates of adaption affect global projections of coral-reef bleaching. The focus of this study was two-fold, to: (1) assess how the impact of Degree-Heating-Month (DHM) thermal stress threshold choice affects potential bleaching predictions and (2) examine the effect of hypothetical adaptation rates of corals to rising temperature. DHM values were estimated using a conventional threshold of 1°C and a variability-based threshold of 2σ above the climatological maximum Coral adaptation rates were simulated as a function of historical 100-year exposure to maximum annual SSTs with a dynamic rather than static climatological maximum based on the previous 100 years, for a given reef cell. Within CCSM3 simulations, the 1°C threshold predicted later onset of mild bleaching every 5 years for the fraction of reef grid cells where 1°C > 2σ of the climatology time series of annual SST maxima (1961–1990). Alternatively, DHM values using both thresholds, with CSIRO MK 3.5 and GFDL CM 2.1 SSTs, did not produce drastically different onset timing for bleaching every 5 years. Across models, DHMs based on 1°C thermal stress threshold show the most threatened reefs by 2100 could be in the Central and Western Equatorial Pacific, whereas use of the variability-based threshold for DHMs yields the Coral Triangle and parts of Micronesia and Melanesia as bleaching hotspots. Simulations that allow corals to adapt to increases in maximum SST drastically reduce the rates of bleaching. These findings highlight the importance of considering the thermal stress threshold in DHM estimates as well as potential adaptation models in future coral bleaching projections.     

淡水湖泊生态系统中砷的赋存与转化行为研究进展

砷(As)是一种无处不在的元素,目前已有很多关于湖泊水体、沉积物、浮游生物、底栖动物、鱼类及水生植物中As的含量分布与赋存形态的研究报道.As在全球淡水湖泊中分布不均,区域差异性较大;湖泊沉积物中As含量水平对底栖动物的自然生境影响很大,甚至造成底栖物种生物区系的改变;水生植物普遍具有富集As的能力,一般表现为沉水植物＞浮水植物＞挺水植物;水生动物中As含量一般为底栖动物＞浮游动物＞鱼类.相对于海洋生态系统,目前对湖泊生态系统环境与生物质中砷的赋存形态及其转化的认识还很不足,今后应加强人类活动影响下我国重要湖泊As的迁移、富集与转化行为的研究.     

Predicting the occurrence of rare Brazilian birds with species distribution models

Species distribution models (SDMs) yield reliable and needed predictions to identify regions that have similar environmental conditions and were used here to predict potential ranges of rare species to identify new localities were they might occur based on their occurrence probability (i.e. niche suitability). We modeled the potential distribution ranges of ten endangered or rare birds from the South American Cerrado biome, using four temperature- and four precipitation-related bioclimatic variables, three topographical variables, and nine different niche modeling methods for each species. We used an ensemble-forecasting approach to reach a consensus scenario to obtain the average distribution for each species based on the five best models generating a distribution map of each species. Model efficiency was related to sample size and not appropriate below ten independent spatial occurrences. The potential distributions of seven species revealed that their occurrence ranges might go beyond their known ranges, but that most of them seem to occur near the regions where they have already been reported. The models of only three species were considered unsatisfactory in helping identify their potential distribution. Models created maps with higher occurrence probability regions where rare Cerrado birds might occur. These range projections can potentially decrease the costs and improve the efficiency of future field searches. On methodological terms, the application of SDMs to predict species ranges should compare different modeling methods and evaluate the effect of sample size on their performance.     

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%).     

Predicting the occurrence of host-associated differentiation in parasitic arthropods: a quantitative literature review

Parasite populations associated with different host species can encounter a variety of isolating reproductive barriers, leading to each population independently accumulating genome-wide genetic differences due to their host associations. This phenomenon is called host-associated differentiation (HAD) and has been proposed as an indicator of early diversification among parasitic arthropods. Although many parasite–host case study systems have been tested for the genetic signature of HAD (e.g., F_ST≥0.15 between sympatric, host-associated populations in the absence of allopatry), it is unknown which isolating reproductive barriers best predict the general occurrence of HAD. HAD development has been attributed to biological and ecological factors that either directly generate reproductive isolation between parasites living on different hosts, such as ‘immigrant inviability’ (i.e., lower fitness of immigrants in non-native environments), or that promote the accumulation of host-specific genetic adaptations, such as the gallmaking feeding mode. In fact, some of these factors are shared across multiple case studies, suggesting that the occurrence of HAD is generalizable and can be predicted based on the incidence of significant biological and ecological factors. By means of a discriminant function analysis (DFA), this research assessed 108 arthropod parasite–host case studies for ecological and biological factors significantly correlated with the occurrence of HAD and whether these factors could be used to distinguish the presence of HAD from its absence. The DFA demonstrated that case studies that developed HAD could be distinguished from case studies that did not develop HAD. The results of the DFA were corroborated by a ‘non-iterative partial least squares’ (NIPALS) discriminant model and a nominal logistic regression. Case studies with HAD could be robustly separated from case studies without HAD based on the incidence of these predictive factors: immigrant inviability, gallmaking, endophagy, recent range invasions of either hosts or parasites, differential host phenology, and differential parasite morphology. These results were used in an infinite random forest analysis to generate a hierarchy of conditional probabilities that separated HAD presence from absence. The results provide researchers with a tool for reliably predicting which untested parasite–host system would likely develop HAD. Immigrant inviability, gallmaking, and their combination were strongly correlated with the presence of HAD, which indicated parasite–host systems with these traits were highly likely to develop HAD. Contrary to expectation, endophagous feeding was negatively correlated with HAD presence, which indicated phytophagous endophagous feeders (excepting gallmakers) were highly unlikely to develop HAD. Furthermore, parasitoids were shown to be just as likely to develop HAD as not. Unfortunately, potentially significant predictive factors (e.g., allochrony) were excluded from analysis because too few case studies have been specifically tested for these factors. Furthermore, this analysis was biased by the lack of ‘negative’ publication results and the overrepresentation of research laboratories that primarily study HAD. Future research should accumulate novel HAD case studies that specifically test for allochrony, differential microbial associations, and morphological differentiation.