Effects of nitrogen deposition on forest biodiversity

Humans have altered global and regional cycles of nitrogen (N) more than any other elements. Increasing N emissions to the atmosphere from accelerating industrialization and production and use of fertilizer N now make N deposition significant not only in densely populated regions of Europe and North America, but also in other parts of the world (e.g., Asia and Latin America). Increased atmospheric N deposition is known to be able to reduce biodiversity in natural and semi-natural ecosystems. It is suggested that N deposition will be the third greatest driver of biodiversity loss on the global scale in this century, after land use and climate change. Based on published study results, we reviewed the impacts of N deposition on forest biodiversity by emphasizing 3 aspects: (1) plant diversity, including arborous plants, understory plants and cryptogam plants; (2) soil microorganism diversity; (3) animal diversity, including underground soil fauna and aboveground herbivores. In general, it was found that N deposition could alter species diversity, and excessive N could reduce species diversity, such as richness and abundance, and even lose special species. We also identified specific mechanisms on how excessive N deposition affected forest biodiversity. Finally, we summarized the current status of research on N deposition in China and in other countries, and proposed potential research activities and recommendations.     

Detecting the footprint of changing atmospheric nitrogen deposition loads on acid grasslands in the context of climate change

Although atmospheric nitrogen (N) deposition and climate changes are both recognized as major components of global change, their interaction at ecosystem level is less well understood. A stratified resampling approach was used to investigate the potential impact of changing levels of atmospheric nitrogen deposition and climate change on species composition of nutrient‐poor acid grasslands within the French Atlantic Domain (FAD). The study was based on a comparison, over a period of 25 years, of 162 past and present vegetation records assigned to the species‐rich Nardus grasslands and distributed in regional community types (CTs). Similarly, the characterization of N deposition and climate was stratified according to (i) past (1980–1990) and present (1995–2005) periods, and (ii) FAD and CT scales. Despite the relatively short time span between sampling periods, significant N deposition and climate changes were detected as well as vegetation changes. Correspondence analysis showed that the relative importance of N deposition and climate in explaining vegetation changes depended on the spatial scale of investigation (FAD vs. local CTs) and the CT. At the FAD scale, the increase of annual mean temperature and decrease of water availability were clearly related to the changes in floristic composition. At the local scale, the most stable CT experienced no significant climate change and a stable load of N deposition, whereas the CTs characterized by the largest floristic changes were associated with dramatic climate changes and moderate loads in both oxidized and reduced N deposition. Despite the narrow gradient of deposition investigated, N deposition was related to significant grassland community changes, depending on the region, i.e. climate context, and on whether N deposition was in the oxidized or reduced form. Our results suggest that N deposition drives grassland composition at the local scale, in interaction with climate, whereas climate changes remain the predominant driver at the FAD scale.     

Impacts of changing climate and atmospheric deposition on N and S drainage losses from a forested watershed of the Adirondack Mountains, New York State

Biogeochemical responses to changing climate and atmospheric deposition were investigated using nitrogen (N) and sulfur (S) mass balances, including dry deposition and organic solutes in the Arbutus Lake watershed in the Adirondack Mountains, New York State. Long‐term monitoring of wet‐only precipitation (NADP/NTN, 1983–2001) and dry deposition (AIRMoN, 1990–2001) at sites adjacent to the watershed showed that concentrations of SO₄^2? in precipitation, SO₄^2? in particles,and SO₂ vapor all declined substantially (P<0.005) in contrast to no marked temporal changes observed for most N constituents (NH₄⁺ in precipitation, HNO₃ vapor, and particulate NO₃^?), except for NO₃^? in precipitation, which showed a small decrease in the late 1990s. From 1983 to 2001, concentrations of SO₄^2? in the lake outlet significantly decreased (?2.1 μeq L^?1 yr^?1, P<0.0001), whereas NO₃^? and dissolved organic N (DON) concentrations showed no consistent temporal trends. With the inclusion of dry deposition and DON fluxes into the mass balance, the retained portion of atmospheric N inputs within the main subcatchment increased from 37% to 60%. Sulfur outputs greatly exceeded inputs even with the inclusion of dry S deposition, while organic S flux represented another source of S output, implying substantial internal S sources. A significant relationship between the annual mean concentrations of SO₄^2? in lake discharge and wet deposition over the last two decades (r=0.64, P<0.01) suggested a considerable influence of declining S deposition on surface water SO₄^2? concentrations, despite substantial internal S sources. By contrast, interannual variations in both NO₃^? concentrations and fluxes in lake discharge were significantly related to year‐to‐year changes in air temperature and runoff. Snowmelt responses to winter temperature fluctuations were crucial in explaining large portions of interannual variations in watershed NO₃^? export during the months preceding spring snowmelt (especially, January–March). Distinctive response patterns of monthly mean concentrations of NO₃^? and DON in the major lake inlet to seasonal changes in air temperature also suggested climatic regulation of seasonal patterns in watershed release of both N forms. The sensitive response of N drainage losses to climatic variability might explain the synchronous patterns of decadal variations in watershed NO₃^? export across the northeastern USA.     

氮沉降对森林生物多样性的影响

从3个方面论述了氮沉降对森林生物多样性影响：（1）森林植物多样性,包括乔木层植物、林下层植物和隐花植物;（2）土壤微生物多样性,主要是细菌和真菌;（3）森林动物多样性：主要包括地下土壤动物和地上草食动物。综合来看,氮沉降改变了物种组成,过量氮沉降降低了生物多样性。同时,也对氮沉降影响生物多样性的机理进行了分析。最后,还探讨了当前在氮沉降对森林生物多样性影响的研究方面存在的问题以及今后研究的方向。     

蝴蝶对全球气候变化响应的研究综述

全球气候变化以及生物对其响应已引起人们的广泛关注。在众多生物中,蝴蝶被公认为是对全球气候变化最敏感的指示物种之一。已有大量的研究结果表明,蝴蝶类群已经在地理分布范围、生活史特性以及生物多样性变化等方面对全球气候变化作出了响应。根据全球范围内蝴蝶类群对气候变化响应的研究资料,尤其是欧美一些长期监测的研究成果,综述了蝴蝶类群在物种分布格局、物候、繁殖、形态特征变化、种群动态以及物种多样性变化等方面对气候变化的响应特征,认为温度升高和极端天气是导致蝴蝶物种分布格局和种群动态变化的主要因素。在此基础上,展望了我国开展蝴蝶类群对气候变化响应方面研究的未来发展趋势。     

The impact of global climate change on tropical forest biodiversity in Amazonia

Aim To model long‐term trends in plant species distributions in response to predicted changes in global climate. Location Amazonia. Methods The impacts of expected global climate change on the potential and realized distributions of a representative sample of 69 individual Angiosperm species in Amazonia were simulated from 1990 to 2095. The climate trend followed the HADCM2GSa1 scenario, which assumes an annual 1% increase of atmospheric CO₂ content with effects mitigated by sulphate forcing. Potential distributions of species in one‐degree grid cells were modelled using a suitability index and rectilinear envelope based on bioclimate variables. Realized distributions were additionally limited by spatial contiguity with, and proximity to, known record sites. A size‐structured population model was simulated for each cell in the realized distributions to allow for lags in response to climate change, but dispersal was not included. Results In the resulting simulations, 43% of all species became non‐viable by 2095 because their potential distributions had changed drastically, but there was little change in the realized distributions of most species, owing to delays in population responses. Widely distributed species with high tolerance to environmental variation exhibited the least response to climate change, and species with narrow ranges and short generation times the greatest. Climate changed most in north‐east Amazonia while the best remaining conditions for lowland moist forest species were in western Amazonia. Main conclusions To maintain the greatest resilience of Amazonian biodiversity to climate change as modelled by HADCM2GSa1, highest priority should be given to strengthening and extending protected areas in western Amazonia that encompass lowland and montane forests.     

Disturbance history mediates climate change effects on subtropical forest biomass and dynamics

The responses of forest communities to interacting anthropogenic disturbances like climate change and logging are poorly known. Subtropical forests have been heavily modified by humans and their response to climate change is poorly understood. We investigated the 9‐year change observed in a mixed conifer‐hardwood Atlantic forest mosaic that included both mature and selectively logged forest patches in subtropical South America. We used demographic monitoring data within 10 1 ha plots that were subjected to distinct management histories (plots logged until 1955, until 1987, and unlogged) to test the hypothesis that climate change affected forest structure and dynamics differentially depending on past disturbances. We determined the functional group of all species based on life‐history affinities as well as many functional traits like leaf size, specific leaf area, wood density, total height, stem slenderness, and seed size data for the 66 most abundant species. Analysis of climate data revealed that minimum temperatures and rainfall have been increasing in the last few decades of the 20th century. Floristic composition differed mainly with logging history categories, with only minor change over the nine annual census intervals. Aboveground biomass increased in all plots, but increases were higher in mature unlogged forests, which showed signs of forest growth associated with increased CO₂, temperature, and rainfall/treefall gap disturbance at the same time. Logged forests showed arrested succession as indicated by reduced abundances of Pioneers and biomass‐accumulators like Large Seeded Pioneers and Araucaria, as well as reduced functional diversity. Management actions aimed at creating regeneration opportunities for long‐lived pioneers are needed to restore community functional diversity, and ecosystem services such as increased aboveground biomass accumulation. We conclude that the effects of climate drivers on the dynamics of Brazilian mixed Atlantic forests vary with land‐use legacies, and can differ importantly from the ones prevalent in better known tropical forests.     

The effects of climate change on species composition,succession and phenology: a case study

Climate change and its role in altering biological interactions and the likelihood of invasion by introduced species in marine systems have received increased attention in recent years. It is difficult to forecast how climate change will influence community function or the probability of invasion as it alters multiple marine environmental parameters including rising water temperature, lower salinity and pH. In the present study, we correlate changes in environmental parameters to shifts in species composition in a subtidal community in Newcastle, NH through comparison of two, 3‐year periods separated by 23 years (1979–1981 and 2003–2005). We observed concurrent shifts in climate related factors and in groups of organisms that dominate the marine community when comparing 1979–1981 to 2003–2005. The 1979–1981 community was dominated by perennial species (mussels and barnacles). In contrast, the 2003–2005 community was dominated by annual native and invasive tunicates (sea‐squirts). We also observed a shift in the environmental factors that characterized both communities. Dissolved inorganic nitrogen and phosphate characterized the 1979–1981 community while sea surface temperature, pH, and chlorophyll a characterized the 2003–2005 community. Elongated warmer water temperatures, through the fall and early winter months of the 2000s, extended the growing season of native organisms and facilitated local dominance of invasive species. Additionally, beta‐diversity was greater between 2003–2005 than 1979–1981 and driven by larger numbers of annual species whose life‐history characteristics (e.g., timing and magnitude of recruitment, growth and mortality) are driven by environmental parameters, particularly temperature.     

Balance between climate change mitigation benefits and land use impacts of bioenergy: conservation implications for European birds

Both climate change and habitat modification exert serious pressure on biodiversity. Although climate change mitigation has been identified as an important strategy for biodiversity conservation, bioenergy remains a controversial mitigation action due to its potential negative ecological and socio-economic impacts which arise through habitat modification by land use change. While the debate continues, the separate or simultaneous impacts of both climate change and bioenergy on biodiversity have not yet been compared. We assess projected range shifts of 156 European bird species by 2050 under two alternative climate change trajectories: a baseline scenario, where the global mean temperature increases by 4 °C by the end of the century, and a 2 degrees scenario, where global concerted effort limits the temperature increase to below 2 °C. For the latter scenario, we also quantify the pressure exerted by increased cultivation of energy biomass as modelled by IMAGE2.4, an integrated land use model. The global bioenergy use in this scenario is in the lower end of the range of previously estimated sustainable potential. Under the assumptions of these scenarios, we find that the magnitude of range shifts due to climate change is far greater than the impact of land conversion to woody bioenergy plantations within the European Union, and that mitigation of climate change reduces the exposure experienced by species. However, we identified potential for local conservation conflict between priority areas for conservation and bioenergy production. These conflicts must be addressed by strict bioenergy sustainability criteria that acknowledge biodiversity conservation needs beyond existing protected areas and apply also to biomass imported from outside the European Union.     

Projected climate change effects on Rocky Mountain and Great Plains birds: generalities of biodiversity consequences

Climate change effects on biodiversity are already manifested, and yet no predictive knowledge characterizes the likely nature of these effects. Previous studies suggested an influence of topography on these effects, a possibility tested herein. Bird species with distributions restricted to montane (26 species) and Great Plains (19 species) regions of central and western North America were modeled, and climate change effects on their distributions compared: in general, plains species were more heavily influenced by climate change, with drastic area reductions (mode 35% of distributional area lost under assumption of no dispersal) and dramatic spatial movements (0–400 km shift of range centroid under assumption of no dispersal) of appropriate habitats. These results suggest an important generality regarding climate change effects on biodiversity, and provide useful guidelines for conservation planning.     

Sensitivity of continental United States atmospheric budgets of oxidized and reduced nitrogen to dry deposition parametrizations

Reactive nitrogen (N_r) is removed by surface fluxes (air–surface exchange) and wet deposition. The chemistry and physics of the atmosphere result in a complicated system in which competing chemical sources and sinks exist and impact that removal. Therefore, uncertainties are best examined with complete regional chemical transport models that simulate these feedbacks. We analysed several uncertainties in regional air quality model resistance analogue representations of air–surface exchange for unidirectional and bi-directional fluxes and their effect on the continental N_r budget. Model sensitivity tests of key parameters in dry deposition formulations showed that uncertainty estimates of continental total nitrogen deposition are surprisingly small, 5 per cent or less, owing to feedbacks in the chemistry and rebalancing among removal pathways. The largest uncertainties (5%) occur with the change from a unidirectional to a bi-directional NH₃ formulation followed by uncertainties in bi-directional compensation points (1–4%) and unidirectional aerodynamic resistance (2%). Uncertainties have a greater effect at the local scale. Between unidirectional and bi-directional formulations, single grid cell changes can be up to 50 per cent, whereas 84 per cent of the cells have changes less than 30 per cent. For uncertainties within either formulation, single grid cell change can be up to 20 per cent, but for 90 per cent of the cells changes are less than 10 per cent.     

A global assessment of forest surface albedo and its relationships with climate and atmospheric nitrogen deposition

We present a global assessment of the relationships between the short‐wave surface albedo of forests, derived from the MODIS satellite instrument product at 0.5° spatial resolution, with simulated atmospheric nitrogen deposition rates (N_dep), and climatic variables (mean annual temperature T_m and total annual precipitation P), compiled at the same spatial resolution. The analysis was performed on the following five forest plant functional types (PFTs): evergreen needle‐leaf forests (ENF); evergreen broad‐leaf forests (EBF); deciduous needle‐leaf forests (DNF); deciduous broad‐leaf forests (DBF); and mixed‐forests (MF). Generalized additive models (GAMs) were applied in the exploratory analysis to assess the functional nature of short‐wave surface albedo relations to environmental variables. The analysis showed evident correlations of albedo with environmental predictors when data were pooled across PFTs: T_m and N_dep displayed a positive relationship with forest albedo, while a negative relationship was detected with P. These correlations are primarily due to surface albedo differences between conifer and broad‐leaf species, and different species geographical distributions. However, the analysis performed within individual PFTs, strengthened by attempts to select ‘pure’ pixels in terms of species composition, showed significant correlations with annual precipitation and nitrogen deposition, pointing toward the potential effect of environmental variables on forest surface albedo at the ecosystem level. Overall, our global assessment emphasizes the importance of elucidating the ecological mechanisms that link environmental conditions and forest canopy properties for an improved parameterization of surface albedo in climate models.     

Assessing effects of forecasted climate change on the diversity and distribution of European higher plants for 2050

The rapidly increasing atmospheric concentrations of greenhouse gases may lead to significant changes in regional and seasonal climate patterns. Such changes can strongly influence the diversity and distribution of species and, therefore, affect ecosystems and biodiversity. To assess these changes we developed a model, called euromove. The model uses climate data from 1990 to 2050 as compiled from the image 2 model, and determines climate envelopes for about 1400 plant species by multiple logistic regression analysis. The climate envelopes were applied to the projected climate to obtain predictions about plant diversity and distributions by 2050. For each European grid cell, euromove calculates which species would still occur in forecasted future climate conditions and which not. The results show major changes in biodiversity by 2050. On average, 32% of the European plant species that were present in a cell in 1990 would disappear from that cell. The area, in which 32% or more of the 1990 species will disappear, takes up 44% of the modelled European area. Individual responses of the plant species to the forecasted climate change were diverse. In reviewing possible future trends, we found that plant species, in general, would find their current climate envelopes further northeast by 2050, shifting ranges that were comparable with those ranges in other studies.     

Impacts of climate change on natural forest productivity – evidence since the middle of the 20th century

Changes to forest production drivers (light, water, temperature, and site nutrient) over the last 55 years have been documented in peer‐reviewed literature. The main objective of this paper is to review documented evidence of the impacts of climate change trends on forest productivity since the middle of the 20th century. We first present a concise overview of the climate controls of forest production, provide evidence of how the main controls have changed in the last 55 years, followed by a core section outlining our findings of observed and documented impacts on forest productivity and a brief discussion of the complications of interpreting trends in net primary production (NPP). At finer spatial scales, a trend is difficult to decipher, but globally, based on both satellite and ground‐based data, climatic changes seemed to have a generally positive impact on forest productivity when water was not limiting. Of the 49 papers reporting forest production levels we reviewed, 37 showed a positive growth trend, five a negative trend, three reported both a positive and a negative trend for different time periods, one reported a positive and no trend for different geographic areas, and two reported no trend. Forests occupy ≈52% of the Earth's land surface and tend to occupy more temperature and radiation‐limited environments. Less than 7% of forests are in strongly water‐limited systems. The combined and interacting effects of temperature, radiation, and precipitation changes with the positive effect of CO₂, the negative effects of O₃ and other pollutants, and the presently positive effects of N will not be elucidated with experimental manipulation of one or a few factors at a time. Assessments of the greening of the biosphere depend on both accurate measurements of rates (net ecosystem exchange, NPP), how much is stored at the ecosystem level (net ecosystem production) and quantification of disturbances rates on final net biome production.     

Effects of climate change on biodiversity: a review and identification of key research issues

Current knowledge of effects of climate change on biodiversity is briefly reviewed, and results are presented of a survey of biological research groups in the Netherlands, aimed at identifying key research issues in this field. In many areas of the world, biodiversity is being reduced by humankind through changes in land cover and use, pollution, invasions of exotic species and possibly climate change. Assessing the impact of climate change on biodiversity is difficult, because changes occur slowly and effects of climate change interact with other stress factors already imposed on the environment. Research issues identified by Dutch scientists can be grouped into: (i) spatial and temporal distributions of taxa; (ii) migration and dispersal potentials of taxa; (iii) genetic diversity and viability of (meta) populations of species; (iv) physiological tolerance of species; (v) disturbance of functional interactions between species; and (vi) ecosystem processes. Additional research should be done on direct effects of greenhouse gases, and on interactions between effects of climate change and habitat fragmentation. There are still many gaps in our knowledge of effects of climate change on biodiversity. An interdisciplinary research programme could possibly focus only on one or few of the identified research issues, and should generate input data for predictive models based on climate change scenarios.     

Invertebrates,ecosystem services and climate change

The sustainability of ecosystem services depends on a firm understanding of both how organisms provide these services to humans and how these organisms will be altered with a changing climate. Unquestionably a dominant feature of most ecosystems, invertebrates affect many ecosystem services and are also highly responsive to climate change. However, there is still a basic lack of understanding of the direct and indirect paths by which invertebrates influence ecosystem services, as well as how climate change will affect those ecosystem services by altering invertebrate populations. This indicates a lack of communication and collaboration among scientists researching ecosystem services and climate change effects on invertebrates, and land managers and researchers from other disciplines, which becomes obvious when systematically reviewing the literature relevant to invertebrates, ecosystem services, and climate change. To address this issue, we review how invertebrates respond to climate change. We then review how invertebrates both positively and negatively influence ecosystem services. Lastly, we provide some critical future directions for research needs, and suggest ways in which managers, scientists and other researchers may collaborate to tackle the complex issue of sustaining invertebrate‐mediated services under a changing climate.     

Biodiversity as a solution to mitigate climate change impacts on the functioning of forest ecosystems

Forest ecosystems are critical to mitigating greenhouse gas emissions through carbon sequestration. However, climate change has affected forest ecosystem functioning in both negative and positive ways, and has led to shifts in species/functional diversity and losses in plant species diversity which may impair the positive effects of diversity on ecosystem functioning. Biodiversity may mitigate climate change impacts on (I) biodiversity itself, as more‐diverse systems could be more resilient to climate change impacts, and (II) ecosystem functioning through the positive relationship between diversity and ecosystem functioning. By surveying the literature, we examined how climate change has affected forest ecosystem functioning and plant diversity. Based on the biodiversity effects on ecosystem functioning (B→EF), we specifically address the potential for biodiversity to mitigate climate change impacts on forest ecosystem functioning. For this purpose, we formulate a concept whereby biodiversity may reduce the negative impacts or enhance the positive impacts of climate change on ecosystem functioning. Further B→EF studies on climate change in natural forests are encouraged to elucidate how biodiversity might influence ecosystem functioning. This may be achieved through the detailed scrutiny of large spatial/long temporal scale data sets, such as long‐term forest inventories. Forest management strategies based on B→EF have strong potential for augmenting the effectiveness of the roles of forests in the mitigation of climate change impacts on ecosystem functioning.     

入侵与本地植物对气候变暖和氮沉降交互效应的动态响应

入侵与本地植物对气候变暖和氮沉降交互效应的动态响应 在全球气候变暖背景下,对入侵物种扩张的预测往往并未考虑到同时出现的氮沉降变化。因此,气候变暖和氮沉降的复杂交互将如何改变入侵物种和本地物种的生长动态尚需进一步探索。在此,本研究假设氮沉降和温度的同时增加可能对入侵植物的生长促进效应大于本地植物。本研究在模拟气候变暖、氮沉降及其交互处理下,对入侵植物加拿大一枝黄花(Solidago canadensis L.)及其本地共存物种艾草(Artemisia argyi Levl. et Van)的生长响应进行温室对照试验。结果表明：由于氮沉降对物种生长的显著促进效应,温度升高和氮沉降的交互作用导致入侵物种和本地物种的生长适应性显著提高,即温氮交互可能使区域微生境更加有利于植物生长。然而,在生物量、高度和直径等生态适应特征方面,入侵物种加拿大一枝黄花的相对增加幅度显著低于本地物种艾草,这表明入侵物种加拿大一枝黄花相对于本地物种艾草的生长优势会在未来气候变暖与氮沉降持续增强的背景下逐渐减弱。因此,纳入氮沉降因素可能会缓解入侵物种加拿大一枝黄花在气候变暖条件下的入侵扩张。