Land management: data availability and process understanding for global change studies

In the light of daunting global sustainability challenges such as climate change, biodiversity loss and food security, improving our understanding of the complex dynamics of the Earth system is crucial. However, large knowledge gaps related to the effects of land management persist, in particular those human‐induced changes in terrestrial ecosystems that do not result in land‐cover conversions. Here, we review the current state of knowledge of ten common land management activities for their biogeochemical and biophysical impacts, the level of process understanding and data availability. Our review shows that ca. one‐tenth of the ice‐free land surface is under intense human management, half under medium and one‐fifth under extensive management. Based on our review, we cluster these ten management activities into three groups: (i) management activities for which data sets are available, and for which a good knowledge base exists (cropland harvest and irrigation); (ii) management activities for which sufficient knowledge on biogeochemical and biophysical effects exists but robust global data sets are lacking (forest harvest, tree species selection, grazing and mowing harvest, N fertilization); and (iii) land management practices with severe data gaps concomitant with an unsatisfactory level of process understanding (crop species selection, artificial wetland drainage, tillage and fire management and crop residue management, an element of crop harvest). Although we identify multiple impediments to progress, we conclude that the current status of process understanding and data availability is sufficient to advance with incorporating management in, for example, Earth system or dynamic vegetation models in order to provide a systematic assessment of their role in the Earth system. This review contributes to a strategic prioritization of research efforts across multiple disciplines, including land system research, ecological research and Earth system modelling.     

The fate of Amazonian ecosystems over the coming century arising from changes in climate,atmospheric CO2, and land use

There is considerable interest in understanding the fate of the Amazon over the coming century in the face of climate change, rising atmospheric CO₂ levels, ongoing land transformation, and changing fire regimes within the region. In this analysis, we explore the fate of Amazonian ecosystems under the combined impact of these four environmental forcings using three terrestrial biosphere models (ED2, IBIS, and JULES) forced by three bias‐corrected IPCC AR4 climate projections (PCM1, CCSM3, and HadCM3) under two land‐use change scenarios. We assess the relative roles of climate change, CO₂ fertilization, land‐use change, and fire in driving the projected changes in Amazonian biomass and forest extent. Our results indicate that the impacts of climate change are primarily determined by the direction and severity of projected changes in regional precipitation: under the driest climate projection, climate change alone is predicted to reduce Amazonian forest cover by an average of 14%. However, the models predict that CO₂ fertilization will enhance vegetation productivity and alleviate climate‐induced increases in plant water stress, and, as a result, sustain high biomass forests, even under the driest climate scenario. Land‐use change and climate‐driven changes in fire frequency are predicted to cause additional aboveground biomass loss and reductions in forest extent. The relative impact of land use and fire dynamics compared to climate and CO₂ impacts varies considerably, depending on both the climate and land‐use scenario, and on the terrestrial biosphere model used, highlighting the importance of improved quantitative understanding of all four factors – climate change, CO₂ fertilization effects, fire, and land use – to the fate of the Amazon over the coming century.     

Meeting Europe's climate change commitments: quantitative estimates of the potential for carbon mitigation by agriculture

Under the Kyoto Protocol, the European Union is committed to a reduction in CO₂ emissions to 92% of baseline (1990) levels during the first commitment period (2008–2012). The Kyoto Protocol allows carbon emissions to be offset by demonstrable removal of carbon from the atmosphere. Thus, land‐use/land‐management change and forestry activities that are shown to reduce atmospheric CO₂ levels can be included in the Kyoto targets. These activities include afforestation, reforestation and deforestation (article 3.3 of the Kyoto Protocol) and the improved management of agricultural soils (article 3.4). In this paper, we estimate the carbon mitigation potential of various agricultural land‐management strategies and examine the consequences of European policy options on carbon mitigation potential, by examining combinations of changes in agricultural land‐use/land‐management. We show that no single land‐management change in isolation can mitigate all of the carbon needed to meet Europe's climate change commitments, but integrated combinations of land‐management strategies show considerable potential for carbon mitigation. Three of the combined scenarios, one of which is an optimal realistic scenario, are by themselves able to meet Europe's emission limitation or reduction commitments. Through combined land‐management scenarios, we show that the most important resource for carbon mitigation in agriculture is the surplus arable land. We conclude that in order to fully exploit the potential of arable land for carbon mitigation, policies will need to be implemented to allow surplus arable land to be put into alternative long‐term land‐use. Of all options examined, bioenergy crops show the greatest potential for carbon mitigation. Bioenergy crop production also shows an indefinite mitigation potential compared to other options where the mitigation potential is finite. We suggest that in order to exploit fully the bioenergy option, the infrastructure for bioenergy production needs to be significantly enhanced before the beginning of the first Kyoto commitment period in 2008. It is not expected that Europe will attempt to meet its climate change commitments solely through changes in agricultural land‐use. A reduction in CO₂‐carbon emissions will be key to meeting Europe's Kyoto targets, and forestry activities (Kyoto Article 3.3) will play a major role. In this study, however, we demonstrate the considerable potential of changes in agricultural land‐use and ‐management (Kyoto Article 3.4) for carbon mitigation and highlight the policies needed to promote these agricultural activities. As all sources of carbon mitigation will be important in meeting Europe's climate change commitments, agricultural carbon mitigation options should be taken very seriously.     

A review of the relationships between drought and forest fire in the United States

The historical and presettlement relationships between drought and wildfire are well documented in North America, with forest fire occurrence and area clearly increasing in response to drought. There is also evidence that drought interacts with other controls (forest productivity, topography, fire weather, management activities) to affect fire intensity, severity, extent, and frequency. Fire regime characteristics arise across many individual fires at a variety of spatial and temporal scales, so both weather and climate – including short‐ and long‐term droughts – are important and influence several, but not all, aspects of fire regimes. We review relationships between drought and fire regimes in United States forests, fire‐related drought metrics and expected changes in fire risk, and implications for fire management under climate change. Collectively, this points to a conceptual model of fire on real landscapes: fire regimes, and how they change through time, are products of fuels and how other factors affect their availability (abundance, arrangement, continuity) and flammability (moisture, chemical composition). Climate, management, and land use all affect availability, flammability, and probability of ignition differently in different parts of North America. From a fire ecology perspective, the concept of drought varies with scale, application, scientific or management objective, and ecosystem.     

Land cover change and management implications for the conservation of a seabird in an urban coastal zone under climate change

Little Penguin (Eudyptula minor) is one of the most ecologically important seabirds in New Zealand and depends strongly on terrestrial ecosystems for nesting, moulting and breeding. Wellington, New Zealand, is one of the world's most important biodiversity hot spots for this species, mostly in confluence with human urban settlements. This species is currently suffering from the local impacts of climate change associated with urbanisation. Two suburbs of Wellington, New Zealand, that are used seasonally by Little Penguin as terrestrial habitat were selected as the study area to address two issues: (i) how local impacts of climate change may affect the population and habitat structure of species in urban coastal zones where land cover change occurs; and (ii) how landscape management practices may help to mitigate the impacts imposed by climate change on the species in such a context. Remote Sensing and Geographical Information Systems techniques were applied to quantify and measure the extent of the prehuman forests and current land cover classes in the study area to reveal the degree to which land cover has changed from predevelopment to the present time. The research shows that land cover change in the study area has been widespread and partly irreversible, particularly in areas covered by the class Built‐up Area. Results reveal that there are still spatial opportunities to safeguard this vulnerable species against the ill effects of climate change through landscape management practices.     

Models meet data: Challenges and opportunities in implementing land management in Earth system models

As the applications of Earth system models (ESMs) move from general climate projections toward questions of mitigation and adaptation, the inclusion of land management practices in these models becomes crucial. We carried out a survey among modeling groups to show an evolution from models able only to deal with land‐cover change to more sophisticated approaches that allow also for the partial integration of land management changes. For the longer term a comprehensive land management representation can be anticipated for all major models. To guide the prioritization of implementation, we evaluate ten land management practices—forestry harvest, tree species selection, grazing and mowing harvest, crop harvest, crop species selection, irrigation, wetland drainage, fertilization, tillage, and fire—for (1) their importance on the Earth system, (2) the possibility of implementing them in state‐of‐the‐art ESMs, and (3) availability of required input data. Matching these criteria, we identify “low‐hanging fruits” for the inclusion in ESMs, such as basic implementations of crop and forestry harvest and fertilization. We also identify research requirements for specific communities to address the remaining land management practices. Data availability severely hampers modeling the most extensive land management practice, grazing and mowing harvest, and is a limiting factor for a comprehensive implementation of most other practices. Inadequate process understanding hampers even a basic assessment of crop species selection and tillage effects. The need for multiple advanced model structures will be the challenge for a comprehensive implementation of most practices but considerable synergy can be gained using the same structures for different practices. A continuous and closer collaboration of the modeling, Earth observation, and land system science communities is thus required to achieve the inclusion of land management in ESMs.     

Temporal patterns in the stability, persistence and condition of stream macroinvertebrate communities: relationships with catchment land-use and regional climate

1. A spatially‐extensive data set of stream macroinvertebrate communities from 49 northern New Zealand sites sampled over a 10‐year period was analysed to assess relationships between the environment (catchment land‐cover, landscape position and regional‐scale weather patterns), and (i) community persistence and stability based on the constancy of species occurrence (presence–absence) and abundance (per cent composition), respectively and (ii) the temporal variability of various community condition metrics. 2. No significant relationship was evident between community stability or persistence within sites and a gradient of increasing land‐use stress (LUS) based on types of upstream land‐cover, with interannual mean similarities at all sites falling within the standard deviations recorded at long‐term reference sites. In contrast, condition metrics were inversely related to LUS. Land‐use appeared to be a key factor influencing community composition among sites whereas climate influenced stability and persistence within sites. 3. Three response trajectories of community variability to increasing LUS were distinguished based on the coefficient of variation of mean interannual similarities, such that (i) persistence and stability appeared to be more variable at developed sites with low LUS and at sites with high stress relative to the variability experienced naturally, but similar to the natural range at intermediate levels of stress (‘sinusoidal response’); (ii) variability in Ephemeroptera, Plecoptera and Trichoptera metrics increased at low‐to‐moderate stress and then accelerated rapidly at highly developed sites (‘stepped‐exponential response’) and (iii) variability in a pollution tolerance metric increased rapidly and then maintained a similar level of variability along the remaining stress gradient (‘plateau response’). 4. The results of this study have implications for biomonitoring approaches that assume high temporal persistence and stability of communities to define site impairment. Misclassifications caused by interannual variability could lead to misinterpretation of site condition, if conclusions are based on single annual surveys. Temporal variability in stability and persistence may help distinguish low levels of impairment where a predominantly healthy fauna experiences increased environmental fluctuations.     

A continent under stress: interactions, feedbacks and risks associated with impact of modified land cover on Australia's climate

Global climate change is the major and most urgent global environmental issue. Australia is already experiencing climate change as evidenced by higher temperatures and more frequent and severe droughts. These impacts are compounded by increasing land use pressures on natural resources and native ecosystems. This paper provides a synthesis of the interactions, feedbacks and risks of natural climate variability, climate change and land use/land cover change (LUCC) impacting on the Australian continent and how they vary regionally. We review evidence of climate change and underlying processes resulting from interactions between global warming caused by increased concentration of atmospheric greenhouse gases and modification of the land surface. The consequences of ignoring the effect of LUCC on current and future droughts in Australia could have catastrophic consequences for the nation's environment, economy and communities. We highlight the need for more integrated, long-term and adaptive policies and regional natural resource management strategies that restore the beneficial feedbacks between native vegetation cover and local-regional climate, to help ameliorate the impact of global warming.     

Climate change-integrated conservation strategies

Aim Conservation strategies currently include little consideration of climate change. Insights about the biotic impacts of climate change from biogeography and palaeoecology, therefore, have the potential to provide significant improvements in the effectiveness of conservation planning. We suggest a collaboration involving biogeography, ecology and applied conservation. The resulting Climate Change‐integrated Conservation Strategies (CCS) apply available tools to respond to the conservation challenges posed by climate change. Location The focus of this analysis is global, with special reference to high biodiversity areas vulnerable to climate change, particularly tropical montane settings. Methods Current tools from climatology, biogeography and ecology applicable to conservation planning in response to climate change are reviewed. Conservation challenges posed by climate change are summarized. CCS elements are elaborated that use available tools to respond to these challenges. Results Five elements of CCS are described: regional modelling; expanding protected areas; management of the matrix; regional coordination; and transfer of resources. Regional modelling uses regional climate models, biotic response models and sensitivity analysis to identify climate change impacts on biodiversity at a regional scale appropriate for conservation planning. Expansion of protected areas management and systems within the planning region are based on modelling results. Management of the matrix between protected areas provides continuity for processes and species range shifts outside of parks. Regional coordination of park and off‐park efforts allows harmonization of conservation goals across provincial and national boundaries. Finally, implementation of these CCS elements in the most biodiverse regions of the world will require technical and financial transfer of resources on a global scale. Main conclusions Collaboration across disciplines is necessary to plan conservation responses to climate change adequately. Biogeography and ecology provide insights into the effects of climate change on biodiversity that have not yet been fully integrated into conservation biology and applied conservation management. CCS provide a framework in which biogeographers, ecologists and conservation managers can collaborate to address this need. These planning exercises take place on a regional level, driven by regional climate models as well as general circulation models (GCMs), to ensure that regional climate drivers such as land use change and mesoscale topography are adequately represented. Sensitivity analysis can help address the substantial uncertainty inherent in projecting future climates and biodiversity response.     

The future of South East Asian rainforests in a changing landscape and climate

With a focus on the Danum Valley area of Sabah, Malaysian Borneo, this special issue has as its theme the future of tropical rainforests in a changing landscape and climate. The global environmental context to the issue is briefly given before the contents and rationale of the issue are summarized. Most of the papers are based on research carried out as part of the Royal Society South East Asia Rainforest Research Programme. The issue is divided into five sections: (i) the historical land-use and land management context; (ii) implications of land-use change for atmospheric chemistry and climate change; (iii) impacts of logging, forest fragmentation (particularly within an oil palm plantation landscape) and forest restoration on ecosystems and their functioning; (iv) the response and resilience of rainforest systems to climatic and land-use change; and (v) the scientific messages and policy implications arising from the research findings presented in the issue.     

Climate change decreases the cooling effect from postfire albedo in boreal North America

Fire is a primary disturbance in boreal forests and generates both positive and negative climate forcings. The influence of fire on surface albedo is a predominantly negative forcing in boreal forests, and one of the strongest overall, due to increased snow exposure in the winter and spring months. Albedo forcings are spatially and temporally heterogeneous and depend on a variety of factors related to soils, topography, climate, land cover/vegetation type, successional dynamics, time since fire, season, and fire severity. However, how these variables interact to influence albedo is not well understood, and quantifying these relationships and predicting postfire albedo becomes increasingly important as the climate changes and management frameworks evolve to consider climate impacts. Here we developed a MODIS‐derived ‘blue sky’ albedo product and a novel machine learning modeling framework to predict fire‐driven changes in albedo under historical and future climate scenarios across boreal North America. Converted to radiative forcing (RF), we estimated that fires generate an annual mean cooling of ?1.77 ± 1.35 W/m² from albedo under historical climate conditions (1971–2000) integrated over 70 years postfire. Increasing postfire albedo along a south–north climatic gradient was offset by a nearly opposite gradient in solar insolation, such that large‐scale spatial patterns in RF were minimal. Our models suggest that climate change will lead to decreases in mean annual postfire albedo, and hence a decreasing strength of the negative RF, a trend dominated by decreased snow cover in spring months. Considering the range of future climate scenarios and model uncertainties, we estimate that for fires burning in the current era (2016) the cooling effect from long‐term postfire albedo will be reduced by 15%–28% due to climate change.     

面向生态系统服务的森林生态系统经营:现状、挑战与展望

森林生态系统是地球陆地生态系统的主体,它具有很高的生物生产力和生物量以及丰富的生物多样性,对全球生态系统和人类经济社会发展起着至关重要和无可替代的作用。伴随着人口的不断增长和经济社会的迅猛发展,对森林资源和森林生态系统服务的需求不断高涨,而且人类对森林资源价值的认识也发生了很大程度的改变。推进森林资源可持续经营,增加森林总量、提高森林质量、增强生态功能,已成为中国林业可持续发展乃至推进中国生态文明建设和建设美丽中国的战略任务。本文全面综述了森林生态系统经营发展历程,分析了森林生态系统经营的现状和存在问题,在此基础上,提出整合基于生态系统管理与满足现代人类福祉对森林多重需求的新的森林生态系统经营理念,面向生态系统服务的森林生态系统经营理念是未来的发展趋势。森林经营发展战略表现为:1)从单纯的森林面积数量扩张,转变到提高单位面积的森林生产力和森林质量;2)从单一追求木材生产逐步转变为多目标经营,将森林林产品单一的经营目标转变为广泛的生态、经济和社会等多目标经营;3)森林经营重点从林分水平转变为森林景观的经营,强调森林景观的时空异质性和动态变化,权衡和协同多种生态系统的服务功能,倡导森林景观的多样性和连通性,提高森林与其它土地利用模式镶嵌构成的复合景观的可持续性和稳定性,增强森林生态系统对气候变化影响的适应能力;4)森林生态系统经营将从依赖传统经验的主观决策转变为信息化、数字化和智能化的决策,发展森林生态系统经营决策支持系统和森林景观恢复与空间经营规划系统。     

A Multilevel Analysis of the Impact of Land Use on Interannual Land-Cover Change in East Africa

Abstract The aim of this study was to characterize the short-term land-cover change processes that were detected in Eastern Africa, based on a set of change metrics that allow for the quantification of interannual changes in vegetation productivity, changes in vegetation phenology and a combination of both. We tested to what extent land use, fire activity and livestock grazing modified the vegetation response to short-term rainfall variability in East Africa and how this is reflected in change metrics derived from MODerate Imaging Spectrometer (MODIS) time series of remote sensing data. We used a hierarchical approach to disentangle the contribution of human activities and climate variability to the patterns of short-term vegetation change in East Africa at different levels of organization. Our results clearly show that land use significantly influences the vegetation response to rainfall variability as measured by time series of MODIS data. Areas with different types of land use react in a different way to interannual climate variability, leading to different values of the change indices depending on the land use type. The impact of land use is more reflected in interannual variability of vegetation productivity and overall change in the vegetation, whereas changes in phenology are mainly driven by climate variability and affect most vegetation types in similar ways. Our multilevel approach led to improved models and clearly demonstrated that climate influence plays at a different scale than land use, fire and herbivore grazing. It helped us to understand dynamics within and between biomes in the study area and investigate the relative importance of different factors influencing short-term variability in change indices at different scales.     

全球变化与生态系统研究现状与展望

全球变化与生态系统研究是一个宏观与微观相互交叉、多学科相互渗透的前沿科学领域, 重点研究生态系统结构和功能对全球变化的响应及反馈作用, 其目标是实现人类对生态系统服务的可持续利用。《植物生态学报》的《全球变化与生态系统》专辑在对国内外全球变化研究进行历史回顾和综合分析的基础上, 总结了全球变化与生态系统研究的阶段性重大进展及存在的主要问题, 并对全球变化研究的前沿方向进行展望和建议。根据研究内容和对象, 该专辑系统地综述了不同全球变化因子, 包括CO₂和O₃浓度升高、气候变暖、降水格局改变、氮沉降增加、土地利用变化等对陆地植物生理生态、群落结构及生态系统功能等的影响以及全球变化对海洋生态系统的影响; 探讨生态系统关键过程以及生物多样性的变化; 在明确全球变化生态效应的基础上, 阐明这些影响对气候和环境变化的反馈机制, 为构筑全球变化的适应对策提供生态学理论基础。     

Co‐benefits,trade‐offs,barriers and policies for greenhouse gas mitigation in the agriculture,forestry and other land use (AFOLU) sector

The agriculture, forestry and other land use (AFOLU) sector is responsible for approximately 25% of anthropogenic GHG emissions mainly from deforestation and agricultural emissions from livestock, soil and nutrient management. Mitigation from the sector is thus extremely important in meeting emission reduction targets. The sector offers a variety of cost‐competitive mitigation options with most analyses indicating a decline in emissions largely due to decreasing deforestation rates. Sustainability criteria are needed to guide development and implementation of AFOLU mitigation measures with particular focus on multifunctional systems that allow the delivery of multiple services from land. It is striking that almost all of the positive and negative impacts, opportunities and barriers are context specific, precluding generic statements about which AFOLU mitigation measures have the greatest promise at a global scale. This finding underlines the importance of considering each mitigation strategy on a case‐by‐case basis, systemic effects when implementing mitigation options on the national scale, and suggests that policies need to be flexible enough to allow such assessments. National and international agricultural and forest (climate) policies have the potential to alter the opportunity costs of specific land uses in ways that increase opportunities or barriers for attaining climate change mitigation goals. Policies governing practices in agriculture and in forest conservation and management need to account for both effective mitigation and adaptation and can help to orient practices in agriculture and in forestry towards global sharing of innovative technologies for the efficient use of land resources. Different policy instruments, especially economic incentives and regulatory approaches, are currently being applied however, for its successful implementation it is critical to understand how land‐use decisions are made and how new social, political and economic forces in the future will influence this process.     

Steps to a sustainable Northern Australia

Summary Northern Australia's globally significant savannas and rivers face major threats, from cattle to weeds to land clearing to climate change. In the face of imperatives and pressures such as reducing carbon emissions, nature conservation, alleviating Indigenous disadvantage, the resources boom and global food security, how should development be managed to protect its globally significant ecosystems? Nine planks in a ‘Sustainable Northern Australia’ agenda are proposed: (i) enhance investment in mitigating pervasive landscape threats; (ii) strengthen support for Indigenous Caring for Country activities and incorporation of Traditional Ecological Knowledge into land management; (iii) align and strengthen invasive species control and management; (iv) facilitate new economic development pathways focused on sustainability; (v) build climate resilience by maintaining and enhancing landscape‐scale connectivity; (vi) protect free‐flowing rivers from dams and major water resource development; (vii) establish and effectively manage a large interconnected network of protected areas; (viii) develop cooperative governance arrangements; and (ix) enhance knowledge generation and research and monitoring capacity.     

Global change and ecosystems research progress and prospect

全球变化与生态系统研究是一个宏观与微观相互交叉、多学科相互渗透的前沿科学领域, 重点研究生态系统结构和功能对全球变化的响应及反馈作用, 其目标是实现人类对生态系统服务的可持续利用。《植物生态学报》的《全球变化与生态系统》专辑在对国内外全球变化研究进行历史回顾和综合分析的基础上, 总结了全球变化与生态系统研究的阶段性重大进展及存在的主要问题, 并对全球变化研究的前沿方向进行展望和建议。根据研究内容和对象, 该专辑系统地综述了不同全球变化因子, 包括CO₂和O₃浓度升高、气候变暖、降水格局改变、氮沉降增加、土地利用变化等对陆地植物生理生态、群落结构及生态系统功能等的影响以及全球变化对海洋生态系统的影响; 探讨生态系统关键过程以及生物多样性的变化; 在明确全球变化生态效应的基础上, 阐明这些影响对气候和环境变化的反馈机制, 为构筑全球变化的适应对策提供生态学理论基础。     

The NSW Environmental Services Scheme: Results for the biodiversity benefits index, lessons learned, and the way forward

Summary   In 2002 the Environmental Services Scheme (ESS) was launched in New South Wales, Australia. Its aim was to pilot a process to provide financial incentives to landholders to undertake changes in land use or land management that improved the status of environmental services (e.g. provision of clean water, healthy soils, biodiversity conservation). To guide the direction of incentive funds, metrics were developed for use by departmental staff to score the benefits of land use or land management changes to a range of environmental services. The purpose of this paper is to (i) report on the development of one of these metrics – the biodiversity benefits index; (ii) present the data generated by field application of the metric to 20 properties contracted to the ESS; and (iii) discuss the lessons learned and recent developments of the metric that aim to make it accessible to a wider range of end-users and applications.     

The effects of land use and climate change on the carbon cycle of Europe over the past 500 years

The long residence time of carbon in forests and soils means that both the current state and future behavior of the terrestrial biosphere are influenced by past variability in climate and anthropogenic land use. Over the last half‐millennium, European terrestrial ecosystems were affected by the cool temperatures of the Little Ice Age, rising CO₂ concentrations, and human induced deforestation and land abandonment. To quantify the importance of these processes, we performed a series of simulations with the LPJ dynamic vegetation model driven by reconstructed climate, land use, and CO₂ concentrations. Although land use change was the major control on the carbon inventory of Europe over the last 500 years, the current state of the terrestrial biosphere is largely controlled by land use change during the past century. Between 1500 and 2000, climate variability led to temporary sequestration events of up to 3 Pg, whereas increasing atmospheric CO₂ concentrations during the 20th century led to an increase in carbon storage of up to 15 Pg. Anthropogenic land use caused between 25 Pg of carbon emissions and 5 Pg of uptake over the same time period, depending on the historical and spatial pattern of past land use and the timing of the reversal from deforestation to afforestation during the last two centuries. None of the currently existing anthropogenic land use change datasets adequately capture the timing of the forest transition in most European countries as recorded in historical observations. Despite considerable uncertainty, our scenarios indicate that with limited management, extant European forests have the potential to absorb between 5 and 12 Pg of carbon at the present day.     

Global environmental change effects on ecosystems: the importance of land‐use legacies

One of the major challenges in ecology is to predict how multiple global environmental changes will affect future ecosystem patterns (e.g. plant community composition) and processes (e.g. nutrient cycling). Here, we highlight arguments for the necessary inclusion of land‐use legacies in this endeavour. Alterations in resources and conditions engendered by previous land use, together with influences on plant community processes such as dispersal, selection, drift and speciation, have steered communities and ecosystem functions onto trajectories of change. These trajectories may be modulated by contemporary environmental changes such as climate warming and nitrogen deposition. We performed a literature review which suggests that these potential interactions have rarely been investigated. This crucial oversight is potentially due to an assumption that knowledge of the contemporary state allows accurate projection into the future. Lessons from other complex dynamic systems, and the recent recognition of the importance of previous conditions in explaining contemporary and future ecosystem properties, demand the testing of this assumption. Vegetation resurvey databases across gradients of land use and environmental change, complemented by rigorous experiments, offer a means to test for interactions between land‐use legacies and multiple environmental changes. Implementing these tests in the context of a trait‐based framework will allow biologists to synthesize compositional and functional ecosystem responses. This will further our understanding of the importance of land‐use legacies in determining future ecosystem properties, and soundly inform conservation and restoration management actions.