Critical role of multidimensional biodiversity in contributing to ecosystem sustainability under global change

The 21st century has seen an acceleration of global change,including climate change,elevated carbon dioxide,nitrogen deposition,and land-use intensification,which poses a significant threat to ecosystem functioning.Nev-ertheless,studies on the relationship between biodiversity and ecosystem functioning(BEF)have consistently demonstrated that biodiversity enhances ecosystem functioning and its stability,even in variable environmental conditions.These findings potentially indicate the critical role of biodiversity in promoting sustainable provi-sioning of ecosystem functioning under global change.Our paper provides a comprehensive review of current BEF research and the response of BEF to multiple global change factors.We demonstrate that(1)assessing the effects of biodiversity on ecosystem functioning requires consideration of multiple dimensions of diversity,such as diversity across multiple trophic levels(plants,animals,and microbes),multiple facets(taxonomy,functional traits,and phylogeny),and multiple spatial scales(local,regional,and landscape scales).(2)The interaction of multiple global change factors may lead to a greater reduction in biodiversity and ecosystem functioning than a single global change factor.(3)Multidimensional biodiversity regulates the response of ecosystem functioning to global change factors,indicating that high levels of multidimensional biodiversity can mitigate the negative impacts of global change on ecosystem functioning.Overall,we emphasize that recognizing the importance of multidimensional biodiversity is critical for sustaining ecosystem functioning.Therefore,prioritizing conserva-tion efforts to maintain and enhance all dimensions of biodiversity is essential to address the challenges of future global change.

Forest biodiversity, relationships to structural and functional attributes, and stability in New England forests

Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although many hypotheses have been developed to interpret global gradients of biodiversity, there has not been complete agreement on mechanisms controlling biodiversity patterns and distributions. Differences may be due to limited observation data and inconsistencies of spatial scales in analysis. Methods： In this study, we take advantage of USDA Forest Service forest inventory and analysis （FIA） data for exploring regional forest biodiversity and BEF in New England forests. The FIA data provide detailed information of sampled plots and trees for the region, including 6000 FIA plots and more than 33,000 individual trees. Biodiversity models were used to analyze the data. Results： Tree species diversity increases from the north to the south at a rate about 2-3 species per latitudinal degree. Tree species diversity is better predicted by tree height than forest age or biomass. Very different distribution patterns of two common maple species, sugar maple （Acer sdcchorum） and red maple （Acer rubrum）, highlight the vulnerability of sugar maple and its potential replacement by red maple on New England landscapes. Red maple generally already outperforms sugar maple, and will likely and continuously benefit from a changing climate in New England. Conclusions： We conclude that forest structure （height） and resources （biomass） are more likely foundational characteristics supporting biodiversity rather than biodiversity determining forest productivity and/or biomass. The potential replacement of red maple for sugar maple in the New England areas could affect biodiversity and stability of forest ecosystem functioning because sugar maple plays important ecological roles distinct from red maple that are beneficial to other tree species in northern hardwood forests. Such a change may not affect forest resilience in terms of forest productivity and biomass as these are similar in red maple and sugar maple, however, it would almost certainly alter forest structure across the landscape.

Changes in biodiversity and ecosystem function during the restoration of a tropical forest in south china

Tropical forests continue to vanish rapidly,but few long-term studies have ever examined if and how the lost forests can be restored.Based on a 45-year restoration study in south China,we found that a tropical rain forest,once completely destroyed,could not recover naturally without deliberate restoration efforts.We identified two kinds of thresholds that must be overcome with human ameliorative measures before the ecosystem was able to recover.The first threshold was imposed primarily by extreme physical conditions such as exceedingly high surface temperature and impoverished soil,while the second was characterized by a critical level of biodiversity and a landscape context that accommodates dispersal and colonization processes.Our three treatment catchments(un-restored barren land,single-species plantation,and mixed-forest stand)exhibited dramatically different changes in biodiversity and ecosystem functioning over 4 decades.The mixed forest,having the highest level of biodiversity and ecosystem functioning,possesses several major properties of tropical rain forest.These findings may have important implications for the restoration of many severely degraded or lost tropical forest ecosystems.

Finding Food Security through Changing the Agricultural Model to Sustain Insect Biodiversity

Worldwide biodiversity is being threatened by human activities to a greater level wherein the natural ecosystems are reaching the verge of collapsing. We are faced with four major interrelated challenges namely a changing climate, biodiversity loss, human population growth and food production for this growing population. Agricultural intensification contributes significantly to biodiversity loss. The agricultural model for our current food production systems is mainly based on the Green Revolution, which promoted the cultivation of crops in extensive monoculture fields and intensified external inputs of agrochemicals. This model resulted in biodiversity loss, particularly in insect populations. A model based on ecological intensification as an alternative to agricultural intensification with minimized use of agro-inputs may slow the rate of biodiversity loss resulting in more sustainable agricultural ecosystems.

Selective logging enhances ecosystem multifunctionality via increase of functional diversity in a Pinus yunnanensis forest in Southwest China

Background:The impacts of selective logging on ecosystem multifunctionality(EMF)remain largely unexplored.In this study,we analyzed the response of nine variables related to four ecosystem functions(i.e.nutrient cycling,soil carbon stocks,decomposition,and wood production)to five selective logging intensities in a Pinus yunnanensisdominated forest.We included a control group with no harvest to evaluate the potential shifts in EMF of the P.yunnanensis forests.We also assessed the relationship between above-and belowground biodiversity and EMF under these different selective logging intensities.Additionally,we evaluated the effects of biotic and abiotic factors on EMF using a structural equation modeling(SEM)approach.Results:Individual ecosystem functions(EFs)all had a significant positive correlation with selective logging intensity.Different EFs showed different patterns with the increase of selective logging intensity.We found that EMF tended to increase with logging intensity,and that EMF significantly improved when the stand was harvested at least twice.Both functional diversity and soil moisture had a significant positive correlation with EMF,but soil fungal operational taxonomic units(OTUs)had a significant negative correlation with EMF.Based on SEM,we found that selective logging improved EMF mainly by increasing functional diversity.Conclusion:Our study demonstrates that selective logging is a good management technique from an EMF perspective,and thus provide us with potential guidelines to improve forest management in P.yunnanensis forests in this region.The functional diversity is maximized through reasonable selective logging measures,so as to enhance EMF.

Evaluating alternative hypotheses behind biodiversity and multifunctionality relationships in the forests of Northeastern China

Background:The importance of biodiversity in maintaining multiple ecosystem functions has been widely accepted.However,the specific mechanisms affecting biodiversity and ecosystem multifunctionality(BEMF)relationships in forests are largely unknown.This is particularly evident for the macroscale of a large forested landscape.Methods:Based on 412 one-tenth hectare field plots distributed over forested areas across northeastern China,we evaluated three alternative hypotheses explaining the relationships between BEMF,namely:niche complementarity,mass ratio,and vegetation quantity effect.We used Rao's quadratic entropy and community weighted mean trait values to quantify forest“biodiversity”.These two variables represent two complementary aspects of functional properties,which are in line with niche complementary and mass ratio effects,respectively.Results:Ecosystem multifunctionality was negatively associated with the community weighted mean values of acquisitive traits(a proxy of mass ratio effect).Rao's quadratic entropy(a proxy of niche complementarity)had no relationship with ecosystem multifunctionality.Higher stand biomass greatly increased ecosystem multifunctionality,which is in line with the vegetation quantity effect.Our results confirm that in the temperate forests of northeastern China,the relationship of BEMF was primarily affected by vegetation quantity,followed by mass ratio effects.Conclusions:The results of this study contribute to a better understanding of the main drivers of ecosystem multifunctionality in forest ecosystems.The results of this study provide additional evidence to support the vegetation quantity and mass ratio hypotheses in forest ecosystems.

The Importance of Insects in Agricultural Ecosystems

Sufficient food production for a growing human population has become an issue of global concern. Almost all of the world’s fertile land is currently in use and arable land areas cannot be expanded significantly. The global challenge is to secure high and quality yields and to make agricultural production environmentally compatible. Insects have been hugely successful in terms of both species richness and abundance. Insects make up the most numerous group of organisms on earth, around 66% of all animal species, and being good dispersers and exploiters of virtually all types of organic matter, can be found almost everywhere, forming an important part of every ecosystem and are vital within our food supply chains performing valuable ecosystem services. Insects have been predominantly perceived as competitors in the race for survival. Herbivorous insects damage 18% of world agricultural production. Despite this damage less than 0.5 percentage of the total number of the known insect species are considered pests. Insect pests are created through the manipulation of habitats by humans, where crops are selected for larger size, higher yields, nutritious value, and are cultivated in monocultures for maximum production. This provides a highly favourable environment for the population increase of herbivorous insects. To ensure stable crop yields we need to change the management strategies of agroecosystems. We need to manage these systems in such a way that insects performing valuable ecosystem services are also incorporated into the system. This will ensure stable, resilient and sustainable systems in a constantly changing environment and will go a long way to ensure future food security. This paper examines the important role that insects generally play in ecosystems and how the services that insects provide can improve agricultural ecosystems.

基于InVEST-Biodiversity模型的闽江流域生境质量变化评价

基于InVEST模型的Biodiversity模块,测定闽江流域的生物多样性生态服务功能,运用模型结果中的生境质量指数和生境稀缺度指数评估闽江流域生态环境质量,对区域生态环境保护具有参考价值。经模型运算得到:2000年、2005年、2010年闽江流域生境质量指数得分分别为27.90、27.82、27.79,10年间下降了0.39%,2005—2010年期间较2000—2005年期间下降速率降低了62.50%;台江、鼓楼、仓山、长乐地区是生境质量较低的地域,其生境质量指数得分10年间均值为0.15、0.23、0.33、0.53;道路、居住地、工业用地、采矿场4种地类对闽江流域生态环境的干扰是生境质量变化的主要驱动因素;森林地类生境稀缺度指数下降了89.80%,生境质量指数10年间均值为0.99,占地面积增加了0.09%。研究表明,10年间闽江流域整体生境质量处于良好水平,且保持稳定。

A set of ecosystem service indicators for European grasslands based on botanical surveys

Background:Grasslands provide a wide range of ecosystem services(ESs).However,there is currently no method for easily diagnosing the level of ESs produced.Our aim was to develop ES indicators based on botanical surveys,which are readily available data and integrative of grassland spatiotemporal variability.Methods:Based on academic knowledge and expertise,we identified several simple vegetation criteria that we aggregated using a multicriteria analysis tool to construct indicators of the level of ESs provided by grasslands.In this study,the indicators were calculated from over 2000 botanical surveys spread over a wide biogeographical gradient.Results:Analyses of correlation between the various indicators show that“forage supply”and“diversity conservation”were not correlated.“Forage availability”and“nitrogen availability for the vegetation”were positively linked together and negatively linked to the robustness of the plant community to extreme events.A temporal approach highlights that the“biodiversity conservation”score decreased from 1970 to 2010 and that“nitrogen availability for the vegetation”was lower in 1970 and 1980 than in 2000 and 2010.Conclusions:These results show that our aggregation method based on a large data set of botanical surveys could be appropriate for studying temporal dynamics of ESs.

Tree structure and diversity shape the biomass of primary temperate mountain forests

Primary forests are spatially diverse terrestrial ecosystems with unique characteristics,being naturally regenerative and heterogeneous,which supports the stability of their carbon storage through the accumulation of live and dead biomass.Yet,little is known about the interactions between biomass stocks,tree genus diversity and structure across a temperate montane primary forest.Here,we investigated the relationship between tree structure(variability in basal area and tree size),genus-level diversity(abundance,tree diversity)and biomass stocks in temperate primary mountain forests across Central and Eastern Europe.We used inventory data from726 permanent sample plots from mixed beech and spruce across the Carpathian Mountains.We used nonlinear regression to analyse the spatial variability in forest biomass,structure,and genus-level diversity and how they interact with plot-level tree age,disturbances,temperature and altitude.We found that the combined effects of genus and structural indices were important for addressing the variability in biomass across different spatial scales.Local processes in disturbance regimes and uneven tree age support forest hete rogeneity and the accumulation of live and dead biomass through the natural regeneration,growth and decay of the forest ecosystem.Structural complexities in basal area index,supporte d by genus-level abundance,positively influence total biomass stocks,which was modulated by tree age and disturbances.Spruce forests showed higher tree density and basal area than mixed beech forests,though mixed beech still contributes significantly to biomass across landscapes.Forest heterogeneity was strongly influenced by complexities in forest composition(tree genus diversity,structure).We addressed the importance of primary forests as stable carbon stores,achieved through structure and diversity.Safeguarding such ecosystems is critical for ensuring the stability of the primary forest,carbon store and biodiversity into the future.

Incorporating novelty and novel ecosystems into restoration planning and practice in the 21st century

Novelty pervades the biosphere.In some cases,potentially irreversible abiotic and/or biotic changes have led to the crossing of thresholds and thus the formation of“novel ecosystems.”Their widespread emergence(particularly on land)and the presence of continued environmental change challenge a traditional restoration goal of restoring an historical ecosystem.Instead,we argue that restoration could broaden its frame of reference to consider how novel ecosystems might be used to maintain global biodiversity and provide ecosystem services and,in doing so,save potentially wasted efforts in attempting to fulfil traditional goals.Here we explore this contention in more depth by addressing:Are novel ecosystems innovative planning or lowering the bar?We show that novel ecosystems were not innovative planning in their original conception.On the contrary,they were recognized as ecosystems that were recalcitrant to traditional restoration approaches,coupled with an awareness that they had arisen inadvertently through deliberate human activity,either on-or off-site.Their recalcitrance to traditional restoration suggests that alternative goals may exist for these ecosystems using sometimes innovative intervention.This management may include biodiversity conservation or restoration for ecological function.We elucidate the latter aspect with reference to an experiment in the wheatbelt of Western Australia—The Ridgefield Multiple Ecosystem Services Experiment—the design of which has been informed by ecological theory and the acceptance of novelty as an ecosystem component.Although novel ecosystems do provide opportunities to broaden restoration planning and practice,and ultimately maintain and conserve global biodiversity in this era of environmental change,they necessarily“lower the bar”in restoration if the bar is considered to be the historical ecosystem.However,in these times of flux,such a bar is increasingly untenable.Instead,careful and appropriate interventions are required at local,regional,and global scales.These interventions need to take history into account,use ecological and evolutionary theory to inform their design,and be mindful of valid concerns such as hubris.Careful interventions thus provide an opportunity for broadening restoration’s framework to focus on maintaining global biodiversity and delivering ecosystem services as well as the traditional goals of restoring historical ecosystems.

Estimation of Throughfall Erosivity in a Highly Diverse Forest Ecosystem Using Sand-Filled Splash Cups

Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open field conditions and forest vegetation. The splash cups were exposed to specific forest stands of different ages and to selected species （Schima superba, Castanopsis eyrei, Daphniphyllum oldhamii, Lithocarpus glaber） in the Gutianshan （古田山） National Nature Reserve （GNNR）. The results of the measurements under forest vegetation show that the erosive power of throughfall drops to be 2.59 times higher compared to the open field. This accentuates the importance of shrub, herb and litter layers in forest ecosystems to protect the soil against erosion. Coalescing drops from leaves and branches （drips） are responsible for this notable gain in erosive power. Moreover, differences in sandloss between the investigated tree species （deciduous, evergreen） revealed that the erosion potential and the spatial heterogeneity of throughfall are species-specific. This highlights the importance of selecting specific species for afforestation projects considering the prevention of soil erosion.

Interspecific and intraspecific variation in specific root length drives aboveground biodiversity effects in young experimental forest stands

Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by interspecific and intraspecific trait variation.Methods We measured tree height of 2493 living individuals in 57 plots and specific root length(SRL)on first-order roots of 368 of these individuals across different species richness levels(1,2,4,8 species)in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China(BEF-China)established in 2009.We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity(RaoQ)and further effects of species interactions by variable components of interspecific and intraspecific functional diversity(community weighted trait similarity and trait dissimilarity,CWS and CWD).Finally,we examined the relationships between biodiversity effects on stand-level tree height and functional diversity(RaoQ,CWS and CWD)in SRL using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.Important Findings Our results show that species richness significantly affected SRL in five and tree height in ten out of 16 species.A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in SRL.A positive CE was related to high values of all three components of root functional diversity(RaoQ,CWS and CWD).Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.

A National Key R&D Program: Technologies and Guidelines for Monitoring Ecological Quality of Terrestrial Ecosystems in China

Ecological quality is defined as the stability, adaptability and resilience of an ecosystem. Monitoring and assessing ecological quality are important bases for China’s ecological civilization construction. The national key research and development program "Technologies and guidelines for monitoring ecological quality of terrestrial ecosystems in China", launched in July 2017, includes plans to study the observation technologies and provide guidelines on the ecological in-situ observation, the regional biodiversity and ecosystem function monitoring and its applications, all of which contribute to national ecological quality assessment. A year after its implementation,some important progress has been achieved, such as building the indicator system for comprehensive monitoring of ecological quality and improvement of the methods, mass data transmission, infrared camera-based monitoring of biodiversity, multi-angle automatic spectral observation systems, and unmanned aerial vehicle(UAV) based desert monitoring. We have organized this special issue and attempted to introduce the monitoring techniques and assessment methods on ecological quality from different perspectives in order to further promote the development of ecology and its observation methods.

Effects of biodiversity,stand factors and functional identity on biomass and productivity during the restoration of subtropical forests in Central China

Biodiversity is found to have a significant promotion effect on ecosystem functions in manipulation experiments on grassland communities.However,its relative role compared with stand factors or functional identity is still controversial in natural forests.Here,we examined their relative effects on biomass and productivity during forest restoration.We investigated stand biomass and productivity for 24 plots(600 m2)across restoration stages in the subtropical forests of Mt.Shennongjia,Central China.We measured five key functional traits and calculated functional diversity(functional richness,evenness and dispersion)and community-weighted mean of traits.We used general linear models,variation partitioning methods to test the relative importance of stand factors(density,stand age,maximum height,etc.),functional identity,species and functional diversity on biomass and productivity.Our results illustrated that stand biomass and productivity increased significantly as forest restoration,and that community species richness increased,while functional dispersion decreased significantly.Variation partitioning analyses showed that diversity had no significant pure effects on biomass and productivity.However,diversity may affect biomass and productivity through the joint effect with stand factors and functional identity.Overall,we found that stand factors had the strongest effect on biomass and productivity,while functional identity significantly affects productivity but not biomass,suggesting that modulating stand structure and species identity are effective ways to enhance forest carbon storage and sequestrations potential in forest management.

一类考虑空间异质环境的湖泊生态系统模型的全局稳定性

本文研究一类空间异质环境下具有扩散的湖泊生态系统模型.引入空间异质环境影响,模型中浮游动物的扩散及相互作用系数具有空间依赖性.本文首先证明了模型解的全局存在和唯一性以及共存平衡解的存在唯一性,通过构造Lyapunov泛函,建立了模型非齐次共存平衡解的全局渐近稳定性条件,并通过数值模拟验证了理论结果.本文推广了含有外来有机物的湖泊生态系统模型,进一步证明了空间异质环境下的扩散不会改变湖泊生态系统共存平衡解的稳定性.

A combination of climate,tree diversity and local human disturbance determine the stability of dry Afromontane forests

Background:Anthropogenic disturbances are increasingly affecting the vitality of tropical dry forests.The future condition of this important biome will depend on its capability to resist and recover from these disturbances.So far,the temporal stability of dryland forests is rarely studied,even though identifying the important factors associated with the stability of the dryland forests could serve as a basis for forest management and restoration.Methodology:In a degraded dry Afromontane forest in northern Ethiopia,we explored remote sensing derived indicators of forest stability,using MODIS satellite derived NDVI time series from 2001 to 2018.Resilience and resistance were measured using the anomalies(remainders)after time series decomposition into seasonality,trend and remainder components.Growth stability was calculated using the integral of the undecomposed NDVI data.These NDVI derived stability indicators were then related to environmental factors of climate,topography,soil,tree species diversity,and local human disturbance,obtained from a systematic grid of field inventory plots,using boosted regression trees in R.Results:Resilience and resistance were adequately predicted by these factors with an R^(2) of 0.67 and 0.48,respectively,but the model for growth stability was weaker.Precipitation of the wettest month,distance from settlements and slope were the most important factors associated with resilience,explaining 51%of the effect.Altitude,temperature seasonality and humus accumulation were the significant factors associated with the resistance of the forest,explaining 61%of the overall effect.A positive effect of tree diversity on resilience was also important,except that the impact of species evenness declined above a threshold value of 0.70,indicating that perfect evenness reduced the resilience of the forest.Precipitation of the wettest month was the most important factor explaining 43.52%of the growth stability variation.Conclusion:A combination of climate,topographic factors and local human disturbance controlled the stability of the dry forest.Also tree diversity is an important stability component that should be considered in the management and restoration programs of such degraded forests.If local disturbances are alleviated the recovery time of dryland forests could be shortened,which is vital to maintain the ecosystem services these forests provide to local communities and global climate change.

保护农业生物多样性建设集约化生态田园

农业集约化引发的农业生物多样性下降及农田系统生态功能失衡退化是农业绿色高质量可持续发展的重要威胁。破解集约化农田系统所存在的问题已成为国内外研究的热点,更是我国农业现代化能否如期实现的关键。本文从我国农业现代化的任务出发,结合农业生态科技发展趋势,从集约化农田系统生态功能减弱、生物多样性维持农田生态系统功能和集约化农田生物多样性保护意识欠缺三个方面分析了集约化农田生物多样性保护现状及存在的问题。针对目前集约化农田系统存在的不可持续的问题,提出了四点工作建议,旨在打造新阶段具有中国特色的集约化生态田园建设范式,向世界提供基于农业生物多样性保护的集约化农业可持续绿色发展的中国智慧和中国方案。

玉溪市生态系统服务功能重要性评价及机理

以玉溪市为研究对象,结合其生态环境的实际情况及数据,对玉溪市生态系统服务功能重要性进行评价,并探究其形成重要性格局的内在机理。结果表明,玉溪市生态系统服务功能重要性主要是极重要,其面积为13556.94 km2,占玉溪市总面积的90.74%;一般重要地区分布较少,分布在玉溪市西南地区,主要分布在元江县;重要地区分布较离散,多分布在玉溪市东部地区,主要分布在红塔区、江川区、海通县、澄江市;极重要地区分布较广,涵盖了玉溪市各县区,主要分布在峨山县、易门县、新平县、华宁县;在不同重要性等级中,耕地和林地的总面积占比较大,耕地面积占比与生态系统服务功能重要性等级呈负相关,林地面积占比与生态系统服务功能重要性等级呈正相关,随着重要性等级的变化,二者呈此消彼长的规律。

An experimental approach to addressing ecological questions related to the conservation of plant biodiversity in China

We briefly introduce and describe seven questions related to community structure and biodiversity conservation that can be addressed using field experiments,and provide the context for using the vast geographic diversity,biodiversity,and network of Nature Reserves in China to perform these experiments.China is the world's third largest country,has a diverse topography,covers five climatic zones from cold-temperate to tropical,has 18 vegetation biomes ranging from Arctic / alpine tundra and desert to Tropical rain forest,and supports the richest biodiversity in the temperate northern hemisphere( > 10%of the world total). But this tremendous natural resource is under relentless assault that threatens to destroy biodiversity and negatively impact the services ecosystems provide. In an attempt to prevent the loss of biodiversity,China has established 2,729 nature reserves which cover 14.84% of the nation' s area. Unfortunately underfunding,mismanagement,illegal activities,invasive species and global climate change threaten the effectiveness of these protected areas. Attention has focused on protecting species and their habitats before degradation and loss of either species or habitats occur. Here we argue that we must move beyond the simple protection of ecosystems,beyond their description,and by using experiments,try to understand how ecosystems work. This new understanding will allow us to design conservation programs,perform restoration of damaged or degraded areas,and address resource management concerns( e.g.,agriculture,logging,mining,hunting) more effectively than with the current approach of ad hoc reactions to ecological and environmental problems. We argue that improving our understanding of nature can best be done using well designed,replicated,and typically manipulative field experiments.