Potential host colonization by insect herbivores in a warmer climate: a transplant experiment

We conducted a transplant experiment to investigate the potential colonization of a plant species by insect herbivores under a warmer climate. Acacia falcata seeds collected from four latitudes, encompassing the current coastal range of the species (1150 km), were grown in the same soil type and climatic conditions in a glasshouse. Plants were then transplanted to two sites, 280 km north of A. falcata's current coastal range; the transplant sites were 1.2 and 5.5°C warmer than the northernmost and southernmost boundaries of the species' current range, respectively. We compared the structure and composition of the herbivorous Hemiptera and Coleoptera communities on the transplants (i) to that of A. falcata within its current distribution, (ii) to a closely related Acacia species (Acacia leptostachya) that naturally occurred at the transplant sites, and (iii) among the A. falcata transplants originating from seeds collected at different latitudes. Herbivory on A. falcata was also compared between the transplants and the current distribution, and among transplant originating from different latitudes. Thirty species of externally feeding herbivorous Coleoptera and Hemiptera were collected from the transplanted A. falcata over a period of 12 months following transplantation. Guild structure of this herbivore community (based on the proportion of species within each of seven groups based on taxonomy and feeding style) did not significantly differ between the transplants and that found on A. falcata within its natural range, but did differ between the transplants and A. leptostachya. Rates of herbivory did not significantly differ between the transplants and plants at sites within the natural range. There were no significant differences in herbivore species richness or overall rates of herbivory on the transplants originating from different latitudes. In conclusion, host plant identity was apparently more important than climate in influencing the structure of the colonizing herbivore community. If this result holds for other plant–herbivore systems, we might expect that under a warmer climate, broad patterns in insect community structure and rates of herbivory may remain similar to that at present, even though species composition may change substantially.     

昆虫植食对植物有性生殖的影响

植物在个体发育的各个阶段都与不同的群落成员相互作用,如竞争的植物、有益的传粉者和敌对的植食动物。昆虫植食在各类生态系统中普遍存在,并可能对植物有性生殖产生各种影响。植食昆虫可通过对植物有性生殖结构的消耗直接对植物生殖产生影响,也可通过影响植物资源分配和花性状等改变传粉者服务,从而间接对植物有性生殖带来正面、负面或中性的影响。同一植物的植食昆虫和传粉者往往对植物的吸引性状 （如花大小、气味、颜色等）有相同的偏好,因此植食者与传粉者均能对植物有性生殖性状施加选择压力。本文从昆虫植食对植物有性生殖的直接影响、间接影响以及植食昆虫对植物有性生殖性状选择的影响三个方面进行综述,以期为昆虫植食和生物资源多样性保护相关研究提供参考。     

Water stress and insect herbivory interactively reduce crop yield while the insect pollination benefit is conserved

Climate change is predicted to hamper crop production due to precipitation deficits and warmer temperatures inducing both water stress and increasing herbivory due to more abundant insect pests. Consequently, crop yields will be impacted simultaneously by abiotic and biotic stressors. Extensive yield losses due to such climate change stressors might, however, be mitigated by ecosystem services such as insect pollination. We examined the single and combined effects of water stress, insect herbivory and insect pollination on faba bean yield components and above‐ and belowground plant biomass under realistic field conditions. We used rainout shelters to simulate a scenario in line with climate change projections, with adequate water supply at sowing followed by a long period without precipitation. This induced a gradually increasing water stress, culminating around crop flowering and yield formation. We found that gradually increasing water stress combined with insect herbivory by aphids interactively shaped yield in faba beans. Individually, aphid herbivory reduced yield by 79% and water stress reduced yield by 52%. However, the combined effect of water stress and aphid herbivory reduced yield less (84%) than the sum of the individual stressor effects. In contrast, insect pollination increased yield by 68% independently of water availability and insect herbivory. Our results suggest that yield losses can be greatly reduced when both water stress and insect herbivory are reduced simultaneously. In contrast, reducing only one stressor has negligible benefits on yield as long as the crop is suffering from the other stressor. We call for further exploration of interactions among ecosystem services and biotic and abiotic stressors that simulate realistic conditions under climate change.     

The implications of predicted climate change for insect pests in the UK, with emphasis on non-indigenous species

Recent estimates for global warming predict increases in global mean surface air temperatures (relative to 1990) of between 1 and 3.5 °C, by 2100. The impact of such changes on agricultural systems in mid- to high-latitude regions are predicted to be less severe than in low-latitude regions, and possibly even beneficial, although the influence of pests and diseases is rarely taken into account. Most studies have concluded that insect pests will generally become more abundant as temperatures increase, through a number of inter-related processes, including range extensions and phenological changes, as well as increased rates of population development, growth, migration and over-wintering. A gradual, continuing rise in atmospheric CO₂ will affect pest species directly (i.e. the CO₂ fertilization effect) and indirectly (via interactions with other environmental variables). However, individual species responses to elevated CO₂ vary: consumption rates of insect herbivores generally increase, but this does not necessarily compensate fully for reduced leaf nitrogen. The consequent effects on performance are strongly mediated via the host species. Some recent experiments under elevated CO₂ have suggested that aphids may become more serious pests, although other studies have discerned no significant effects on sap-feeding homopterans. However, few, if any of these experiments have fully considered the effects on pest population dynamics. Climate change is also considered from the perspective of changes in the distribution and abundance of species and communities. Marked changes in the distribution of well-documented species – including Odonata, Orthoptera and Lepidoptera – in north-western Europe, in response to unusually hot summers, provide useful indications of the potential effects of climate change. Migrant pests are expected to respond more quickly to climate change than plants, and may be able to colonize newly available crops/habitats. Range expansions, and the removal of edge effects, could result in the increased abundance of species presently near the northern limits of their ranges in the UK. However, barriers to range expansions, or shifts, may include biotic (competition, predation, parasitism and disease), as well as abiotic, factors. Climatic phenomena, ecosystem processes and human activities are interactive and interdependent, making long-term predictions extremely tenuous. Nevertheless, it appears prudent to prepare for the possibility of increases in the diversity and abundance of pest species in the UK, in the context of climate change.     

Multigenerational experimental simulation of climate change on an economically important insect pest

Long‐term multigenerational experimental simulations of climate change on insect pests of economically and socially important crops are crucial to anticipate challenges for feeding humanity in the not‐so‐far future. Mexican bean weevil Zabrotes subfasciatus, is a worldwide pest that attacks the common bean Phaseolus vulgaris seeds, in crops and storage. We designed a long term (i.e., over 10 generations), experimental simulation of climate change by increasing temperature and CO₂ air concentration in controlled conditions according to model predictions for 2100. Higher temperature and CO₂ concentrations favored pest''s egg‐to‐adult development survival, even at high female fecundity. It also induced a reduction of fat storage and increase of protein content but did not alter body size. After 10 generations of simulation, genetic adaptation was detected for total lipid content only, however, other traits showed signs of such process. Future experimental designs and methods similar to ours, are key for studying long‐term effects of climate change through multigenerational experimental designs.     

Global patterns of insect herbivory in gap and understorey environments,and their implications for woody plant carbon storage

Insect herbivory is thought to favour carbon allocation to storage in juveniles of shade‐tolerant trees. This argument assumes that insect herbivory in the understorey is sufficiently intense as to select for storage; however, understoreys might be less attractive to insect herbivores than canopy gaps, because of low resource availability and – at temperate latitudes – low temperatures. Although empirical studies show that shade‐tolerant species in tropical forests do allocate more photosynthate to storage than their light‐demanding associates, the same pattern has not been consistently observed in temperate forests. Does this reflect a latitudinal trend in the relative activity of insect herbivory in gap versus understorey environments? To date there has been no global review of the effect of light environment on insect herbivory in forests. We postulated that if temperature is the primary factor limiting insect herbivory, the effect of gaps on rates of insect herbivory should be more evident in temperate than in tropical forests; due to low growing season temperatures in the oceanic temperate forests of the Southern Hemisphere, the effect of gaps on insect herbivory rates should in turn be stronger there than in the more continental temperate climates of the Northern Hemisphere. We examined global patterns of insect herbivory in gaps versus understories through meta‐analysis of 87 conspecific comparisons of leaf damage in contrasting light environments. Overall, insect herbivory in gaps was significantly higher than in the understorey; insect herbivory was 50% higher in gaps than in understoreys of tropical forests but did not differ significantly between gaps and understories in temperate forests of either hemisphere. Results are consistent with the idea that low resource availability – and not temperature – limits insect herbivore activity in forest understoreys, especially in the tropics, and suggest the selective influence of insect herbivory on late‐successional tree species may have been over‐estimated.     

Potential effects of climate change on plant species in the Faroe Islands

Aim To identify the effect of climate change on selected plant species representative of the main vegetation types in the Faroe Islands. Due to a possible weakening of the North Atlantic Current, it is difficult to predict whether the climate in the Faroe Islands will be warmer or colder as a result of global warming. Therefore, two scenarios are proposed. The first scenario assumes an increase in summer and winter temperature of 2 °C, and the second a decrease in summer and winter temperature of 2 °C. Location Temperate, low alpine and alpine areas in the northern and central part of the Faroe Islands. Methods The responses of 12 different plant species in the Faroe Islands were tested against measured soil temperature, expressed as T_min, T_max, snow cover and growing degree days (GDD), using generalised linear modelling (GLM). Results The tolerance to changes in winter soil temperature (0.3–0.8 °C) was found to be lower than the tolerance to changing summer soil temperature (0.7–1.0 °C), and in both cases lower than the predicted climate changes. Conclusions The species most affected by a warming scenario are those that are found with a limited distribution restricted to the uppermost parts of the mountains, especially Salix herbacea, Racomitrium fasciculare, and Bistorta vivipara. For other species, the effect will mainly be a general upward migration. The most vulnerable species are those with a low tolerance, especially Calluna vulgaris, and also Empetrum nigrum, and Nardus stricta. If the climate in the Faroe Islands should become colder, the most vulnerable species are those at low altitudes. A significantly lower temperature would be expected to produce a serious reduction in the extent of Vaccinium myrtillus and Galium saxatilis. Species like Empetrum nigrum, Nardus stricta, and Calluna vulgaris may also be vulnerable. In any case, these species can be expected to migrate downwards.     

Elevational gradients in plant defences and insect herbivory: recent advances in the field and prospects for future research

Classic research on elevational gradients in plant–herbivore interactions holds that insect herbivore pressure is stronger under warmer, less seasonal climates characteristic of low elevations, and that this in turn selects for increased defence in low‐ (relative to high‐) elevation plants. However, recent work has questioned this paradigm, arguing that it overly simplifies the ecological complexity in which plant–insect herbivore interactions are embedded along elevational gradients. Numerous biotic and abiotic factors vary with elevation, and their simultaneous influences are the focus of current work on elevational gradients in insect herbivory and plant defences. The present review 1) synthesizes current knowledge on elevational gradients in plant–insect herbivore interactions; 2) critically analyses research gaps and highlights recent advances that contribute to filling these gaps; and 3) outlines new research opportunities to uncover underlying mechanisms and build towards a unified theory on elevational gradients. We conclude that the next generation of studies should embrace community complexity – including multi‐trophic dynamics and the multivariate nature of plant defence – and to do so by combining observational data, manipulative experiments and emerging analytical tools.     

Elevated air temperature alters an old-field insect community in a multifactor climate change experiment

To address how multiple, interacting climate drivers may affect plant–insect community associations, we sampled insects that naturally colonized a constructed old‐field plant community grown for over 2 years under simultaneous CO₂, temperature, and water manipulation. Insects were sampled using a combination of sticky traps and vacuum sampling, identified to morphospecies and the insect community with respect to abundance, richness, and evenness quantified. Individuals were assigned to four broad feeding guilds in order to examine potential trophic level effects. Although there were occasional effects of CO₂ and water treatment, the effects of warming on the insect community were large and consistent. Warming significantly increased Order Thysanoptera abundance and reduced overall morphospecies richness and evenness. Nonmetric multidimensional scaling found that only temperature affected insect community composition, while a Sørensen similarity index showed less correspondence in the insect community between temperature treatments compared with CO₂ or soil water treatments. Within the herbivore guild, elevated temperature significantly reduced richness and evenness. Corresponding reductions of diversity measures at higher trophic levels (i.e. parasitoids), along with the finding that herbivore richness was a significant predictor of parasitoid richness, suggest trophic‐level effects within the insect community. When the most abundant species were considered in temperature treatments, a small number of species increased in abundance at elevated temperature, while others declined compared with ambient temperature. Effects of temperature in the dominant insects demonstrated that treatment effects were limited to a relatively small number of morphospecies. Observed effects of elevated CO₂ concentration on whole‐community foliar N concentration did not result in any effect on herbivores, which are probably the most susceptible guild to changes in plant nutritional quality. These results demonstrate that climatic warming may alter certain insect communities via effects on insect species most responsive to a higher temperature, contributing to a change in community structure.     

Historical and projected interactions between climate change and insect voltinism in a multivoltine species

Climate change can cause major changes to the dynamics of individual species and to those communities in which they interact. One effect of increasing temperatures is on insect voltinism, with the logical assumption that increases in surface temperatures would permit multivoltine species to increase the number of generations per year. Though insect development is primarily driven by temperature, most multivoltine insect species rely on photoperiodic cues, which do not change from year‐to‐year or in response to climate warming, to initiate diapause. Thus, the relationship between climate change and voltinism could be complex. We use a phenology model for grape berry moth, Paralobesia viteana (Clemens), which incorporates temperature‐dependent development and diapause termination, and photoperiod‐dependent diapause induction, to explore historical patterns in year‐to‐year voltinism fluctuations. We then extend this model to predict voltinism under varying scenarios of climate change to show the importance of both the quality and quantity of accumulated heat units. We also illustrate that increases in mean surface temperatures > 2 °C can have dramatic effects on insect voltinism by causing a shift in the ovipositional period that currently is subject to diapause‐inducing photoperiods.     

Temperature effects on forest understorey plants in hedgerows: a combined warming and transplant experiment

Background and AimsHedgerows have been shown to improve forest connectivity, leading to an increased probability of species tracking the shifting bioclimatic envelopes. However, it is still unknown how species in hedgerows respond to temperature changes, and whether effects differ compared with those in nearby forests. We aimed to elucidate how ongoing changes in the climate system will affect the efficiency of hedgerows in supporting forest plant persistence and migration in agricultural landscapes.MethodsHere we report results from the first warming experiment in hedgerows. We combined reciprocal transplantation of plants along an 860-km latitudinal transect with experimental warming to assess the effects of temperature on vegetative growth and reproduction of two common forest herbs (Anemone nemorosa and Geum urbanum) in hedgerows versus forests.Key ResultsBoth species grew taller and produced more biomass in forests than in hedgerows, most likely due to higher competition with ruderals and graminoids in hedgerows. Adult plant performance of both species generally benefitted from experimental warming, despite lower survival of A. nemorosa in heated plots. Transplantation affected the species differently: A. nemorosa plants grew taller, produced more biomass and showed higher survival when transplanted at their home site, indicating local adaptation, while individuals of G. urbanum showed greater height, biomass, reproductive output and survival when transplanted northwards, likely owing to the higher light availability associated with increasing photoperiod during the growing season.ConclusionsThese findings demonstrate that some forest herbs can show phenotypic plasticity to warming temperatures, potentially increasing their ability to benefit from hedgerows as ecological corridors. Our study thus provides novel insights into the impacts of climate change on understorey plant community dynamics in hedgerows, and how rising temperature can influence the efficiency of these corridors to assist forest species’ persistence and colonization within and beyond their current distribution range.     

气候变化对中国农作物虫害发生的影响

基于1961—2010年全国农区527个气象站点气象资料、全国病虫害资料以及农作物种植面积等资料,对全国虫害发生面积与气象因子采用相关分析法,分析了气象要素变化对虫害发生的影响。结果表明:气候变化背景下,年平均温度、平均降水强度分别以0.27℃.10a-1、0.24mm.(d.10a)-1的速度增长,年日照时数以47.40h.10a-1的速度减小;年降水量增长速率为0.14mm.10a-1,但波动较大;虫害发生面积率距平与平均温度、平均降水强度距平呈显著正相关,平均温度、平均降水强度分别每增加1℃、1mm.d-1,虫害发生面积率增加0.648、0.713,虫害发生面积将增加0.96、1.06亿hm2次;虫害发生面积率距平与年日照时数距平呈显著负相关,其每降低100h,虫害发生面积率增加0.40,虫害发生面积将增加0.59亿hm2次;总体上,虫害发生面积率距平与年降水量距平的关系不明显。虫害发生面积率距平与年平均小雨量、微雨量雨日数、小雨量雨日数距平呈显著负相关,3个因子分别每减少1mm、1d、1d,虫害发生面积率增加0.014、0.066、0.052,发生面积将增加0.02、0.10、0.08亿hm2次。     

Weak latitudinal gradients in insect herbivory for dominant rangeland grasses of North America

Patterns of insect herbivory may follow predictable geographical gradients, with greater herbivory at low latitudes. However, biogeographic studies of insect herbivory often do not account for multiple abiotic factors (e.g., precipitation and soil nutrients) that could underlie gradients. We tested for latitudinal clines in insect herbivory as well as climatic, edaphic, and trait‐based drivers of herbivory. We quantified herbivory on five dominant grass species over 23 sites across the Great Plains, USA. We examined the importance of climate, edaphic factors, and traits as correlates of herbivory. Herbivory increased at low latitudes when all grass species were analyzed together and for two grass species individually, while two other grasses trended in this direction. Higher precipitation was related to more herbivory for two species but less herbivory for a different species, while higher specific root length was related to more herbivory for one species and less herbivory for a different species. Taken together, results highlight that climate and trait‐based correlates of herbivory can be highly contextual and species‐specific. Patterns of insect herbivory on dominant grasses support the hypothesis that herbivory increases toward lower latitudes, though weakly, and indicates that climate change may have species‐specific effects on plant–herbivore interactions.     

浙江天童常绿阔叶林中11种常绿乔灌木叶片虫食状分析

为探讨昆虫对植物叶片的取食行为和伤害方式,作者选择浙江天童常绿阔叶林内的11种常绿乔灌木为对象,对叶片虫食状类型和格局进行分析。结果如下:(1)共发现16种虫食状类型,每种植物叶片虫食状类型数在10–13种之间,每种虫食状出现频率在0.5–28.7%之间。缘食状出现频率最高(28.7%),虫瘿和泡状出现频率最低(0.5%)。(2)叶片虫食状分布格局可分为3种类型,即一种虫食状占绝对优势的单优格局,如马银花(Rhododendronovatum)和檵木(Loropetalumchinense);两种虫食状(缘食状和顶食状)共占优势的双优格局,仅有木荷(Schimasu-perba);3种及3种以上虫食状占优势的多优格局(其余8种植物)。(3)叶片虫食状多样性指数变化在1.57–2.23之间,最高为苦槠(Castanopsissclerophylla),最低为马银花;乔木的多样性指数(2.040)高于灌木(1.882),优势种多样性指数高于伴生种,但差异均不显著;多样性指数反映了虫食状类型和出现频率的综合差异。(4)16种虫食状类型中有8对显著正相关,4对显著负相关,可能反映出不同类型昆虫取食植物的趋同和差异。     

Potential impacts of climate change on the winter distribution of Afro-Palaearctic migrant passerines

We modelled the present and future sub-Saharan winter distributions of 64 trans-Saharan migrant passerines to predict the potential impacts of climate change. These predictions used the recent ensemble modelling developments and the latest IPCC climatic simulations to account for possible methodological uncertainties. Results suggest that 37 species would face a range reduction by 2100 (16 of these by more than 50%); however, the median range size variation is −13 per cent (from −97 to +980%) under a full dispersal hypothesis. Range centroids were predicted to shift by 500±373 km. Predicted changes in range size and location were spatially structured, with species that winter in southern and eastern Africa facing larger range contractions and shifts. Predicted changes in regional species richness for these long-distance migrants are increases just south of the Sahara and on the Arabian Peninsula and major decreases in southern and eastern Africa.     

Potential impacts of climate change on Sub-Saharan African plant priority area selection

The Global Strategy for Plant Conservation (GSPC) aims to protect 50% of the most important areas for plant diversity by 2010. This study selects sets of 1-degree grid cells for 37 sub-Saharan African countries on the basis of a large database of plant species distributions. We use two reserve selection algorithms that attempt to satisfy two of the criteria set by the GSPC. The grid cells selected as important plant cells (IPCs) are compared between algorithms and in terms of country and continental rankings between cells. The conservation value of the selected grid cells are then considered in relation to their future species complement given the predicted climate change in three future periods (2025, 2055, and 2085). This analysis uses predicted climate suitability for individual species from a previous modelling exercise.
We find that a country-by-country conservation approach is suitable for capturing most, but not all, continentally IPCs. The complementarity-based reserve selection algorithms suggest conservation of a similar set of grid cells, suggesting that areas of high plant diversity and rarity may be well protected by a single pattern of conservation activity.
Although climatic conditions are predicted to deteriorate for many species under predicted climate change, the cells selected by the algorithms are less affected by climate change predictions than non-selected cells. For the plant species that maintain areas of climatic suitability in the future, the selected set will include cells with climate that is highly suitable for the species in the future. The selected cells are also predicted to conserve a large proportion of the species richness remaining across the continent under climate change, despite the network of cells being less optimal in terms of future predicted distributions.
Limitations to the modelling are discussed in relation to the policy implications for those implementing the GSPC.     

Adaptations to water gradient in three Rorippa plant species correspond with plant resistance against insect herbivory under drought and waterlogged conditions

1. Plants live in environments where they are constantly, and often simultaneously, exposed to different types of biotic and abiotic stress, such as insect herbivory and water availability. How plants are adapted to abiotic conditions may determine how a surplus or shortage of water affects plant resistance to insect herbivory. Moreover, this effect may vary depending on the feeding mode of the herbivore.
2. We explored how three closely related Rorippa plant species that vary in adaptations to different water levels, resist herbivory by four different insects (aphids: Myzus persicae, Lipaphis erysimi, and caterpillars: Pieris brassicae, Plutella xylostella) under waterlogging or drought conditions. We hypothesized that plants that are differently adapted to water availability will be disparately affected by water availability in their resistance to insect herbivory.
3. On the semi-aquatic plant species Rorippa amphibia, both aphid species reached a larger colony size under drought conditions. This indicates that R. amphibia was compromised in resistance to aphid feeding when under drought conditions, to which it is less well adapted. Water conditions did not affect aphid performance on the flood-plain species Rorippa palustris. On the terrestrial plant species Rorippa sylvestris, aphids performed worse on waterlogged than drought-treated plants. Neither caterpillar species was significantly affected by the water availability of their food plant.
4. Our findings suggest that water availability can have distinct effects on plant–insect interactions. We propose that plant adaptations to water conditions can be a major predictor towards explaining the variation of effects that water availability can have on plant–insect interactions.

     

两种不同种植方式对龙葵叶片虫食状的影响研究

昆虫与植被之间相互关系的深入研究,有助于更好的理解生态系统结构与功能之间的关系以及生态系统生物多样性维持机理。本文通过对集中种植和分块种植下两种不同种植方式龙葵叶片虫食状进行调查分析,以期对龙葵的栽培和养护提供理论基础和技术建议。研究结果表明:龙葵叶片中共识别出11种虫食状类型,其中,集中种植方式有10种,分块种植方式有11种,各种虫食状类型出现频率在0.4%-24.7%;集中种植样地的龙葵叶片虫食状种类数、Shannon-Wiener指数和Pielou均匀度指数均低于分块种植;分块种植的龙葵叶片受到植食性昆虫的伤害频率较高,但是集中种植的龙葵叶片受到的伤害程度却明显高于分块种植方式。因此,种植龙葵应尽量避免大规模集中种植方式,不同生态系统边界之间边缘效应的尺度和强弱的关系是未来研究的重点和核心问题。     

Hydrologic effects on riparian vegetation in a boreal river: an experiment testing climate change predictions

Climate change is expected to alter the magnitude and variation of flow in streams and rivers, hence providing new conditions for riverine communities. We evaluated plant ecological responses to climate change by transplanting turfs of riparian vegetation to new elevations in the riparian zone, thus simulating expected changes in water‐level variation, and monitored the results over 6 years. Turfs moved to higher elevations decreased in biomass and increased in species richness, whereas turfs transplanted to lower elevations gained biomass but lost species. Transplanted plant communities responded slowly to the new hydrologic conditions. After 6 years, biomass of transplanted turfs was statistically indistinguishable from target level controls, but species richness and species composition of transplants were intermediate between original and target levels. By using projections of future stream flow according to IPCC climate change scenarios, we predict likely changes to riparian vegetation in boreal rivers. Climate‐driven hydrologic changes are predicted to result in narrower riparian zones along the studied Vindel River in northern Sweden towards the end of the 21st century. Present riparian plant communities are projected to be replaced by terrestrial communities at high elevations as a result of lower‐magnitude spring floods, and by amphibious or aquatic communities at low elevations as a result of higher autumn and winter flows. Changes to riparian vegetation may be larger in other boreal climate regions: snow melt fed spring floods are predicted to disappear in southern parts of the boreal zone, which would result in considerable loss of riparian habitat. Our study emphasizes the importance of long‐term ecological field experiments given that plant communities often respond slowly and in a nonlinear fashion to external pressures.     

典型高寒植物生长繁殖特征对模拟气候变化的短期响应

高寒植物的生长繁殖策略对气候变化的响应十分敏感但研究较少。在青藏高原东北的祁连山南麓坡地,于2007年沿3200～3800m海拔进行了植被的等距双向移栽实验并研究了典型高寒植物的生长繁殖策略对模拟气候变化的响应。结果表明,移栽样线年平均气温随海拔升高的递减率为0.51℃/100m。高寒植物移栽到高海拔后,其株高、基叶数、最大(小)叶面积等生长性状指标均发生显著变化,呈现出在3400m海拔处最高,其余3海拔处较低的趋势;而生殖枝数、花数和有性繁殖投入等生殖策略的响应则不明显,但具有随海拔升高而降低,最后在3800m处升高的变化。结果印证了气候变化对高寒植物生长性状的影响比生殖策略快速的假说。