Biological invasions and climate change amplify each other’s effects on dryland degradation

Climate models predict that, in the coming decades, many arid regions will experience increasingly hot conditions and will be affected more frequently by drought. These regions are also experiencing rapid vegetation change, notably invasion by exotic grasses. Invasive grasses spread rapidly into native desert ecosystems due, in particular, to interannual variability in precipitation and periodic fires. The resultant destruction of non-fire-adapted native shrub and grass communities and of the inherent soil resource heterogeneity can yield invader-dominated grasslands. Moreover, recurrent droughts are expected to cause widespread physiological stress and mortality of both invasive and native plants, as well as the loss of soil resources. However, the magnitude of these effects may differ between invasive and native grasses, especially under warmer conditions, rendering the trajectory of vegetated communities uncertain. Using the Biosphere 2 facility in the Sonoran Desert, we evaluated the viability of these hypothesized relationships by simulating combinations of drought and elevated temperature (+5°C) and assessing the ecophysiological and mortality responses of both a dominant invasive grass (Pennisetum ciliare or buffelgrass) and a dominant native grass (Heteropogan contortus or tanglehead). While both grasses survived protracted drought at ambient temperatures by inducing dormancy, drought under warmed conditions exceeded the tolerance limits of the native species, resulting in greater and more rapid mortality than exhibited by the invasive. Thus, two major drivers of global environmental change, biological invasion and climate change, can be expected to synergistically accelerate ecosystem degradation unless large-scale interventions are enacted.     

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。     

Species and community responses to short‐term climate manipulation: Microarthropods in the sub‐Antarctic

Abstract: Both species and community‐level investigations are important for understanding the biotic impacts of climate change, because current evidence suggests that individual species responses are idiosyncratic. However, few studies of climate change impacts have been conducted on entire terrestrial arthropod communities living in the same habitat in the southern Hemisphere, and the effects of precipitation changes on them are particularly poorly understood. Here we investigate the species‐ and community‐level responses of microarthropods inhabiting a keystone plant species, on sub‐Antarctic Marion Island, to experimental reduction in precipitation, warming and shading. These climate manipulations were chosen based on observed climate trends and predicted indirect climate change impacts on this system. The dry‐warm and shade inducing treatments that were imposed effected significant species‐ and community‐level responses after a single year. Although the strongest community‐level trends included a dramatic decline in springtail abundance and total biomass under the dry‐warm and shade treatments, species responses were generally individualistic, that is, springtails responded differently to mites, and particular mite and springtail species responded differently to each other. Our results therefore provide additional support for the dynamic rather than static model for community responses to climate change, in the first such experiment in the sub‐Antarctic. In conclusion, these results show that an ongoing decline in precipitation and increase in temperature is likely to have dramatic direct and indirect effects on this microarthropod community. Moreover, they indicate that while at a broad scale it may be possible to make generalizations regarding species responses to climate change, these generalizations are unlikely to translate into predictable effects at the community level.     

Changes in biocrust cover drive carbon cycle responses to climate change in drylands

Dryland ecosystems account for ca. 27% of global soil organic carbon (C) reserves, yet it is largely unknown how climate change will impact C cycling and storage in these areas. In drylands, soil C concentrates at the surface, making it particularly sensitive to the activity of organisms inhabiting the soil uppermost levels, such as communities dominated by lichens, mosses, bacteria and fungi (biocrusts). We conducted a full factorial warming and rainfall exclusion experiment at two semiarid sites in Spain to show how an average increase of air temperature of 2–3 °C promoted a drastic reduction in biocrust cover (ca. 44% in 4 years). Warming significantly increased soil CO₂ efflux, and reduced soil net CO₂ uptake, in biocrust‐dominated microsites. Losses of biocrust cover with warming through time were paralleled by increases in recalcitrant C sources, such as aromatic compounds, and in the abundance of fungi relative to bacteria. The dramatic reduction in biocrust cover with warming will lessen the capacity of drylands to sequester atmospheric CO₂. This decrease may act synergistically with other warming‐induced effects, such as the increase in soil CO₂ efflux and the changes in microbial communities to alter C cycling in drylands, and to reduce soil C stocks in the mid to long term.     

Insights from modeling studies on how climate change affects invasive alien species geography

Climate change and biological invasions are threatening biodiversity and ecosystem services worldwide. It has now been widely acknowledged that climate change will affect biological invasions. A large number of studies have investigated predicted shifts and other changes in the geographic ranges of invasive alien species related to climate change using modeling approaches. Yet these studies have provided contradictory evidence, and no consensus has been reached. We conducted a systematic review of 423 modeling case studies included in 71 publications that have examined the predicted effects of climate change on those species. We differentiate the approaches used in these studies and synthesize their main results. Our results reaffirm the major role of climate change as a driver of invasive alien species distribution in the future. We found biases in the literature both regarding the taxa, toward plants and invertebrates, and the areas of the planet investigated. Despite these biases, we found for the plants and vertebrates studied that climate change will more frequently contribute to a decrease in species range size than an increase in the overall area occupied. This is largely due to oceans preventing terrestrial invaders from spreading poleward. In contrast, we found that the ranges of invertebrates and pathogens studied are more likely to increase following climate change. An important caveat to these findings is that researchers have rarely considered the effects of climate change on transport, introduction success, or the resulting impacts. We recommend closing these research gaps, and propose additional avenues for future investigations, as well as opportunities and challenges for managing invasions under climate change.     

森林凋落物分解及其对全球气候变化的响应

凋落物分解是重要的森林生态系统过程之一,受到气候、凋落物质量、土壤生物群落等生物和非生物因素的综合调控．迄今,有关不同森林生态系统和不同树种地上部分的凋落物动态、凋落物分解过程中的养分释放动态、生物和非生物因素对凋落物分解的影响等研究报道较多,但对地下凋落物的分解研究相对较少．近年来,森林凋落物分解对以大气CO2浓度增加和温度升高为主要特征的全球变化的响应逐步受到重视,但其研究结果仍具有很多不确定性．因此,未来凋落物生态研究的重点应是凋落物分解对土壤有机碳固定的贡献、地上／地下凋落物的物理、化学和生物学过程及其对各种生态因子（例如冻融、干湿交替）及交互作用的响应、凋落物特别是地下凋落物分解对全球气候变化的响应机制等方面．     

Leaf‐trait plasticity and species vulnerability to climate change in a Mongolian steppe

Climate change is expected to modify plant assemblages in ways that will have major consequences for ecosystem functions. How climate change will affect community composition will depend on how individual species respond, which is likely related to interspecific differences in functional traits. The extraordinary plasticity of some plant traits is typically neglected in assessing how climate change will affect different species. In the Mongolian steppe, we examined whether leaf functional traits under ambient conditions and whether plasticity in these traits under altered climate could explain climate‐induced biomass responses in 12 co‐occurring plant species. We experimentally created three probable climate change scenarios and used a model selection procedure to determine the set of baseline traits or plasticity values that best explained biomass response. Under all climate change scenarios, plasticity for at least one leaf trait correlated with change in species performance, while functional leaf‐trait values in ambient conditions did not. We demonstrate that trait plasticity could play a critical role in vulnerability of species to a rapidly changing environment. Plasticity should be considered when examining how climate change will affect plant performance, species' niche spaces, and ecological processes that depend on plant community composition.     

Response of nitrogen cycling to simulated climate change: differential responses along a subalpine ecotone

In situ nitrogen (N) transformations and N availability were examined over a four‐year period in two soil microclimates (xeric and mesic) under a climate‐warming treatment in a subalpine meadow/sagebrush scrub ecotone. Experimental plots that spanned the two soil microclimates were exposed to an in situ infrared (IR) climate change manipulation at the Rocky Mountain Biological Laboratory, near Crested Butte, Colorado. Although the two microclimates did not differ significantly in their rates of N transformations in the absence of heating, they differed significantly in their response to increased IR. Under a simulated warming in the sagebrush‐dominated xeric microclimate, gross N mineralization rates doubled and immobilization rates increased by up to 60% over the first 2 years of the study but declined to predisturbance rates by the fourth year. This temporal pattern of gross mineralization rates correlated with a decline in SOM. Concurrently, rates of net mineralization rates in the heated plots were 60% higher than the controls after the first year. There were no differences in gross or net nitrification rates with heating in the xeric soils. In contrast to the xeric microclimate, there were no significant effects of heating on any N transformation rates in the mesic microclimate. The differing responses in N cycling rates of the two microclimate to the increased IR is most certainly the result of differences in initial soil moisture conditions and vegetation type and cover.     

Thermal plasticity of photosynthesis: the role of acclimation in forest responses to a warming climate

The increasing air temperatures central to climate change predictions have the potential to alter forest ecosystem function and structure by exceeding temperatures optimal for carbon gain. Such changes are projected to threaten survival of sensitive species, leading to local extinctions, range migrations, and altered forest composition. This study investigated photosynthetic sensitivity to temperature and the potential for acclimation in relation to the climatic provenance of five species of deciduous trees, Liquidambar styraciflua, Quercus rubra, Quercus falcata, Betula alleghaniensis, and Populus grandidentata. Open‐top chambers supplied three levels of warming (+0, +2, and +4 °C above ambient) over 3 years, tracking natural temperature variability. Optimal temperature for CO₂ assimilation was strongly correlated with daytime temperature in all treatments, but assimilation rates at those optima were comparable. Adjustment of thermal optima was confirmed in all species, whether temperatures varied with season or treatment, and regardless of climate in the species' range or provenance of the plant material. Temperature optima from 17° to 34° were observed. Across species, acclimation potentials varied from 0.55 °C to 1.07 °C per degree change in daytime temperature. Responses to the temperature manipulation were not different from the seasonal acclimation observed in mature indigenous trees, suggesting that photosynthetic responses should not be modeled using static temperature functions, but should incorporate an adjustment to account for acclimation. The high degree of homeostasis observed indicates that direct impacts of climatic warming on forest productivity, species survival, and range limits may be less than predicted by existing models.     

入侵昆虫对全球气候变化的响应

生物入侵已成为一个影响深远的全球性问题,其对我国的生态系统、环境和社会经济的负面影响日益明显。全球气候变化对入侵昆虫有着深刻的影响,它正改变着一些昆虫本地种与入侵昆虫的组成、分布、种群动态和种间关系。本文分析了气候变化与生物入侵之间的互作关系,综述了全球气候变化因子(如温度、湿度及其它气候因子)对入侵昆虫生物学及生态学的影响,探讨了气候变化导致入侵昆虫定殖和传播的原因,并提出了气候变化下入侵昆虫的防治对策。     

Predicting species distribution and abundance responses to climate change: why it is essential to include biotic interactions across trophic levels

Current predictions on species responses to climate change strongly rely on projecting altered environmental conditions on species distributions. However, it is increasingly acknowledged that climate change also influences species interactions. We review and synthesize literature information on biotic interactions and use it to argue that the abundance of species and the direction of selection during climate change vary depending on how their trophic interactions become disrupted. Plant abundance can be controlled by aboveground and belowground multitrophic level interactions with herbivores, pathogens, symbionts and their enemies. We discuss how these interactions may alter during climate change and the resulting species range shifts. We suggest conceptual analogies between species responses to climate warming and exotic species introduced in new ranges. There are also important differences: the herbivores, pathogens and mutualistic symbionts of range-expanding species and their enemies may co-migrate, and the continuous gene flow under climate warming can make adaptation in the expansion zone of range expanders different from that of cross-continental exotic species. We conclude that under climate change, results of altered species interactions may vary, ranging from species becoming rare to disproportionately abundant. Taking these possibilities into account will provide a new perspective on predicting species distribution under climate change.     

生物土壤结皮对全球气候变化的响应

生物土壤结皮在干旱、半干旱区和极地、亚极地区等脆弱生态区广泛存在,生物土壤结皮对脆弱生态系统的稳定、碳氮循环和生态平衡等具有重要的生态意义.概述了脆弱生态区生物结皮的碳氮循环与气候变化关系,综合分析了脆弱生态区生物结皮对气候变暖、降水变化和UV-B增加的响应.分析认为应该加强区域尺度下干旱与半旱区生物结皮对气候变化响应研究.     

Breathing life into climate change adaptation

The exploration of evolutionary biology and biological adaptation can inform society's adaptation to climate change, particularly the mechanisms that bring about adaptability, such as phenotypic plasticity, epigenetics, and horizontal gene transfer. Learning from unplanned autonomous biological adaptation may be considered undesirable and incompatible with human endeavor. However, it is argued that there is no need for agency, and planned adaptation is not necessarily preferable over autonomous adaptation. What matters is the efficacy of adaptive mechanisms and their capacity to increase societal resilience to current and future impacts. In addition, there is great scope for industrial ecology (IE) to contribute approaches to climate change adaptation that generate system models and baseline data to inform decision making. The problem of “uncertainty” was chosen as an example of a challenge that is shared by biological systems, IE, and climate change adaptation to show how biological adaptation might contribute solutions. Finally, the Coastal Climate Adaptation Decision Support tool was used to demonstrate how IE and biological adaptation approaches may be mainstreamed in climate change adaptation planning and practice. In conclusion, there is close conceptual alignment between evolutionary biology and IE. The integration of biological adaptation thinking can enrich IE, add new perspectives to climate change adaptation science, and support IE's engagement with climate change adaptation. There should be no major obstacles regarding the collaboration of industrial ecologists with the climate change adaptation community, but mainstreaming of biological adaptation solutions depends greatly on successful knowledge transfer and the engagement of open‐minded and informed adaptation stakeholders.     

Landscape fragmentation affects responses of avian communities to climate change

Forecasting the consequences of climate change is contingent upon our understanding of the relationship between biodiversity patterns and climatic variability. While the impacts of climate change on individual species have been well‐documented, there is a paucity of studies on climate‐mediated changes in community dynamics. Our objectives were to investigate the relationship between temporal turnover in avian biodiversity and changes in climatic conditions and to assess the role of landscape fragmentation in affecting this relationship. We hypothesized that community turnover would be highest in regions experiencing the most pronounced changes in climate and that these patterns would be reduced in human‐dominated landscapes. To test this hypothesis, we quantified temporal turnover in avian communities over a 20‐year period using data from the New York State Breeding Atlases collected during 1980–1985 and 2000–2005. We applied Bayesian spatially varying intercept models to evaluate the relationship between temporal turnover and temporal trends in climatic conditions and landscape fragmentation. We found that models including interaction terms between climate change and landscape fragmentation were superior to models without the interaction terms, suggesting that the relationship between avian community turnover and changes in climatic conditions was affected by the level of landscape fragmentation. Specifically, we found weaker associations between temporal turnover and climatic change in regions with prevalent habitat fragmentation. We suggest that avian communities in fragmented landscapes are more robust to climate change than communities found in contiguous habitats because they are comprised of species with wider thermal niches and thus are less susceptible to shifts in climatic variability. We conclude that highly fragmented regions are likely to undergo less pronounced changes in composition and structure of faunal communities as a result of climate change, whereas those changes are likely to be greater in contiguous and unfragmented habitats.     

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。     

气候变化背景下生物入侵研究态势的文献计量分析

生物入侵严重威胁生物多样性与生态系统健康,对全球环境、经济造成极大损失,而快速的气候变化显著影响外来生物的扩散和入侵进程。探讨气候变化背景下生物入侵研究态势能够从宏观上把握该领域的国际研究现状与热点,为深入理解外来种入侵机制和制定合理的防治策略提供参考。该文基于最近27 a间(1990—2016年)科学文献数据库Web of Science中科学引文索引扩展版(SCI-E)数据,利用TDA等统计工具对气候变化下生物入侵方面的研究进行了文献计量分析。结果表明:27 a间共发表论文1 736篇,论文数量整体保持增长态势,2009年开始进入快速发展阶段;该领域的研究涉及环境科学与生态学、生物多样性保护、植物学等多个学科;澳大利亚莫纳什大学Chown SL教授发文量最高(35篇);美国的总发文量(708篇)和高被引、高影响因子论文数量均居世界首位;发文量最多的研究机构是加利福尼亚大学(93篇),中国科学院发文量居世界第10位(27篇);Biological Invasions是刊文量最大的学术杂志;物种分布模型、生物多样性、全球变暖、风险评估等是近年来该领域的研究热点;中国共发表论文52篇,中国科学院是国内最大的发文机构,其中,动物研究所、武汉植物园、植物研究所的发文量居中科院科研系统前三名;中国在气候变化下生物入侵领域的高被引、高影响因子论文数量及国际合作强度亟待提升。未来需重点关注气候变化下生物入侵的预测与风险评估、生物入侵与生物多样性关系、入侵物种的系统进化、入侵生态系统的多营养级关系、海洋生物入侵、生物入侵与人类健康等问题。     

Penguin responses to climate change in the Southern Ocean

Penguins are adapted to live in extreme environments, but they can be highly sensitive to climate change, which disrupts penguin life history strategies when it alters the weather, oceanography and critical habitats. For example, in the southwest Atlantic, the distributional range of the ice‐obligate emperor and Adélie penguins has shifted poleward and contracted, while the ice‐intolerant gentoo and chinstrap penguins have expanded their range southward. In the Southern Ocean, the El Niño‐Southern Oscillation and the Southern Annular Mode are the main modes of climate variability that drive changes in the marine ecosystem, ultimately affecting penguins. The interaction between these modes is complex and changes over time, so that penguin responses to climate change are expected to vary accordingly, complicating our understanding of their future population processes. Penguins have long life spans, which slow microevolution, and which is unlikely to increase their tolerance to rapid warming. Therefore, in order that penguins may continue to exploit their transformed ecological niche and maintain their current distributional ranges, they must possess adequate phenotypic plasticity. However, past species‐specific adaptations also constrain potential changes in phenology, and are unlikely to be adaptive for altered climatic conditions. Thus, the paleoecological record suggests that penguins are more likely to respond by dispersal rather than adaptation. Ecosystem changes are potentially most important at the borders of current geographic distributions, where penguins operate at the limits of their tolerance; species with low adaptability, particularly the ice‐obligates, may therefore be more affected by their need to disperse in response to climate and may struggle to colonize new habitats. While future sea‐ice contraction around Antarctica is likely to continue affecting the ice‐obligate penguins, understanding the responses of the ice‐intolerant penguins also depends on changes in climate mode periodicities and interactions, which to date remain difficult to reproduce in general circulation models.