Rewilding complex ecosystems Perino, Andrea; Pereira, Henrique M; Navarro, Laetitia M ...
Science (American Association for the Advancement of Science),
04/2019, Volume:
364, Issue:
6438
Journal Article
Peer reviewed
Open access
The practice of rewilding has been both promoted and criticized in recent years. Benefits include flexibility to react to environmental change and the promotion of opportunities for society to ...reconnect with nature. Criticisms include the lack of a clear conceptualization of rewilding, insufficient knowledge about possible outcomes, and the perception that rewilding excludes people from landscapes. Here, we present a framework for rewilding that addresses these concerns. We suggest that rewilding efforts should target trophic complexity, natural disturbances, and dispersal as interacting processes that can improve ecosystem resilience and maintain biodiversity. We propose a structured approach to rewilding projects that includes assessment of the contributions of nature to people and the social-ecological constraints on restoration.
Farmland abandonment is a widespread land-use change in temperate regions, due to increasing yields on productive lands, conservation policies, and the increasing imports of agricultural products ...from other regions. Assessing the environmental outcomes of abandonment and the potential for recultivation hinges on incomplete knowledge about the spatial patterns of fallow and abandoned farmland, especially at broad geographic scales. Our goals were to develop a methodology to map active and fallow land using MODIS Normalized Differenced Vegetation Index (NDVI) time series and to provide the first European-wide map of the extent of abandoned farmland (cropland and grassland) and recultivation. We used a geographically well-distributed training dataset to classify active and fallow farmland annually from 2001 to 2012 using a Random Forests classifier and validated the maps using independent observations from the field and from satellite images. The annual maps had an average overall accuracy of 90.1% (average user's accuracy of the fallow class was 73.9%), and we detected an average of 128.7 million hectares (Mha) of fallow land (24.4% of all farmland). Using the fallow/active time series, we mapped fallow frequency and hotspots of farmland abandonment and recultivation of unused farmland. We found a total of 46.1Mha of permanently fallow farmland, much of which may be linked to abandonment that occurred after the dissolution of the Eastern Bloc. Up to 7.6Mha of farmland was additionally abandoned from 2001 to 2012, mainly in Eastern Europe, Southern Scandinavia, and Europe's mountain regions. Yet, recultivation is widespread too (up to 11.2Mha) and occurred predominantly in Eastern Europe (e.g., European Russia, Poland, Belarus, Ukraine, and Lithuania) and in the Balkans. We also tested the robustness of our maps in relation to different abandonment and recultivation definitions, highlighting the usefulness of time series approaches to overcome problems when mapping transient land-use change. Our maps provide, to our knowledge, the first European-wide assessment of fallow, abandoned and recultivated farmland, thereby forming a basis for assessing the environmental outcomes of abandonment and recultivation and the potential of unused land for food production, bioenergy, and carbon storage.
•Mapping active and fallow farmland across Europe using MODIS NDVI time series•Translating land-use information into management intensity and land-use change trajectories•Approach allows various definitions of farmland abandonment and recultivation.•Farmland abandonment continues to be a crucial land change process in Europe.•Recultivation of unused farmland increasingly outweighs farmland abandonment.
Aligning food production with biodiversity conservation is one of the greatest challenges of our time. One framing of this challenge is the land-sharing vs. land-sparing debate. Much empirical ...research has focused on identifying the relationship between agricultural yields and species populations, and using the relative number of species with particular relationships to inform landscape-level management. We feel this is misguided, as such an approach does not guarantee the existence of every species of conservation concern. Here, we show that constrained optimization methods can be used to identify landscape-level solutions which maximize agricultural yields and populations for any number of species. Our results suggest that the relative number of species with particular yield-density curves is not a good indicator as to how landscapes should be managed. Likewise, choosing between blanket sharing or sparing strategies leads to suboptimal outcomes at the landscape scale in many cases. Our framework makes maximum use of the rich information contained in yield-density curves to move beyond black-and-white choices and toward more nuanced, context-specific solutions to aligning biodiversity conservation and agricultural production. Such optimal landscapes will likely have features of both sharing and sparing strategies.
Many traditional farming landscapes have high conservation value. Conservation policy in such landscapes typically follows a “preservation strategy,” most commonly by providing financial incentives ...for farmers to continue traditional practices. A preservation strategy can be successful in the short term, but it fails to acknowledge that traditional farming landscapes evolved as tightly coupled social–ecological systems. Traditionally, people received direct benefits from the environment, which provided a direct incentive for sustainable land use. Globalization and rural development programs increasingly alter the social subsystem in traditional farming landscapes, whereas conservation seeks to preserve the ecological subsystem. The resulting decoupling of the social–ecological system can be counteracted only in part by financial incentives, thus inherently limiting the usefulness of a preservation strategy. An alternative way to frame conservation policy in traditional farming landscapes is a “transformation strategy.” This strategy acknowledges that the past cannot be preserved, and assumes that direct links between people and nature are preferable to indirect links based on incentive payments. A transformation strategy seeks to support community‐led efforts to create new, direct links with nature. Such a strategy could empower rural communities to embrace sustainable development, providing a vision for the future rather than attempting to preserve the past.
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Research on landscape change drivers covers multiple disciplines, methods, and scales.Research biases are revealed related to biogeographic regions and land systems.Land ...abandonment is the most frequent driver of landscape change in Europe.Combinations of underlying drivers determine landscape change, not single drivers.
Over the past decades, landscapes worldwide have experienced changes (e.g., urbanization, agricultural intensification, expansion of renewable energy uses) at magnitudes that put their sustainability at risk. The understanding of the drivers of these landscape changes remains challenging, partly because landscape research is spread across many domains and disciplines. We here provide a systematic synthesis of 144 studies that identify the proximate and underlying drivers of landscape change across Europe. First, we categorize how driving forces have been addressed and find that most studies consider medium-term time scales and local spatial scales. Most studies assessed only one case study area, one spatial scale, and less than four points in time. Second, we analyze geographical coverage of studies and reveal that countries with a non-European Union/European Free Trade Association membership; low Gross Domestic Product; boreal, steppic, and arctic landscapes; as well as forestland systems are underrepresented in the literature. Third, our review shows that land abandonment/extensification is the most prominent (62% of cases) among multiple proximate drivers of landscape change. Fourthly, we find that distinct combinations of mainly political/institutional, cultural, and natural/spatial underlying drivers are determining landscape change, rather than single key drivers. Our systematic review indicates knowledge gaps that can be filled by: (a) expanding the scope of studies to include underrepresented landscapes; (b) clarifying the identification and role of actors in landscape change; (c) deploying more robust tools and methods to quantitatively assess the causalities of landscape change; (d) setting up long-term studies that go beyond mapping land-cover change only; (e) strengthening cross-site and cross-country comparisons of landscape drivers; (f) designing multi-scale studies that consider teleconnections; (g) considering subtle and novel processes of landscape change.
Global agricultural production will likely need to increase in the future due to population growth, changing diets, and the rising importance of bioenergy. Intensifying already existing cropland is ...often considered more sustainable than converting more natural areas. Unfortunately, our understanding of cropping patterns and intensity is weak, especially at broad geographic scales. We characterized and mapped cropping systems in Europe, a region containing diverse cropping systems, using four indicators: (a) cropping frequency (number of cropped years), (b) multi-cropping (number of harvests per year), (c) fallow cycles, and (d) crop duration ratio (actual time under crops) based on the MODIS Normalized Difference Vegetation Index (NDVI) time series from 2000 to 2012. Second, we used these cropping indicators and self-organizing maps to identify typical cropping systems. The resulting six clusters correspond well with other indicators of agricultural intensity (e.g., nitrogen input, yields) and reveal substantial differences in cropping intensity across Europe. Cropping intensity was highest in Germany, Poland, and the eastern European Black Earth regions, characterized by high cropping frequency, multi-cropping and a high crop duration ratio. Contrarily, we found lowest cropping intensity in eastern Europe outside the Black Earth region, characterized by longer fallow cycles. Our approach highlights how satellite image time series can help to characterize spatial patterns in cropping intensity-information that is rarely surveyed on the ground and commonly not included in agricultural statistics: our clustering approach also shows a way forward to reduce complexity when measuring multiple indicators. The four cropping indicators we used could become part of continental-scale agricultural monitoring in order to identify target regions for sustainable intensification, where trade-offs between intensification and the environmental should be explored.
Widespread changes of agricultural land use occurred in Eastern Europe since the collapse of socialism and the European Union’s eastward expansion, but the rates and patterns of recent land changes ...remain unclear. Here we assess agricultural land change for the entire Carpathian ecoregion in Eastern Europe at 30 m spatial resolution with Landsat data and for two change periods, between 1985–2000 and 2000–2010. The early period is characterized by post-socialist transition processes, the late period by an increasing influence of EU politics in the region. For mapping and change detection, we use a machine learning approach (random forests) on image composites and variance metrics which were derived from the full decadal archive of Landsat imagery. Our results suggest that cropland abandonment was the most prevalent change process, but we also detected considerable areas of grassland conversion and forest expansion on non-forest land. Cropland abandonment was most extensive during the transition period and predominantly occurred in marginal areas with low suitability for agriculture. Conversely, we observed substantial recultivation of formerly abandoned cropland in high-value agricultural areas since 2000. Hence, market forces increasingly adjust socialist legacies of land expansive production and agricultural land use clusters in favorable areas while marginal lands revert to forest.
Agriculture is the leading driver of biodiversity loss. However, its future impact on biodiversity remains unclear, especially because agricultural intensification is often neglected, and high ...path-dependency is assumed when forecasting agricultural development-although the past suggests that shock events leading to considerable agricultural change occur frequently. Here, we investigate the possible impacts on biodiversity of pathways of expansion and intensification. Our pathways are not built to reach equivalent production targets, and therefore they should not be directly compared; they instead highlight areas at risk of high biodiversity loss across the entire option space of possible agricultural change. Based on an extensive database of biodiversity responses to agriculture, we find 30% of species richness and 31% of species abundances potentially lost because of agricultural expansion across the Amazon and Afrotropics. Only 21% of high-risk expansion areas in the Afrotropics overlap with protected areas (compared with 43% of the Neotropics). Areas at risk of biodiversity loss from intensification are found in India, Eastern Europe and the Afromontane region (7% species richness, 13% abundance loss). Many high-risk regions are not adequately covered by conservation prioritization schemes, and have low national conservation spending and high agricultural growth. Considering rising agricultural demand, we highlight areas where timely land-use planning may proactively mitigate biodiversity loss.
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