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Journal ArticleDOI

The Importance of Land-Use Legacies to Ecology and Conservation

TL;DR: In this article, the importance of land-use history and its legacies in most ecological systems has been recognized as a legitimate and essential subject of environmental science, and recognition of these historical legacies adds explanatory power to our understanding of modern conditions at scales from organisms to the globe and reduces missteps in anticipating or managing for future conditions.
Abstract: Recognition of the importance of land-use history and its legacies in most ecological systems has been a major factor driving the recent focus on human activity as a legitimate and essential subject of environmental science. Ecologists, conservationists, and natural resource policymakers now recognize that the legacies of land-use activities continue to influence ecosystem structure and function for decades or centuries—or even longer—after those activities have ceased. Consequently, recognition of these historical legacies adds explanatory power to our understanding of modern conditions at scales from organisms to the globe and reduces missteps in anticipating or managing for future conditions. As a result, environmental history emerges as an integral part of ecological science and conservation planning. By considering diverse ecological phenomena, ranging from biodiversity and biogeochemical cycles to ecosystem resilience to anthropogenic stress, and by examining terrestrial and aquatic ecosyst...

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Journal ArticleDOI
TL;DR: In this paper, the authors presented the first characterization of terrestrial biomes based on global patterns of sustained, direct human interaction with ecosystems and identified the anthropogenic biomes through empirical analysis of global population, land use, and land cover.
Abstract: Humans have fundamentally altered global patterns of biodiversity and ecosystem processes. Surprisingly, existing systems for representing these global patterns, including biome classifications, either ignore humans altogether or simplify human influence into, at most, four categories. Here, we present the first characterization of terrestrial biomes based on global patterns of sustained, direct human interaction with ecosystems. Eighteen “anthropogenic biomes” were identified through empirical analysis of global population, land use, and land cover. More than 75% of Earth's ice-free land showed evidence of alteration as a result of human residence and land use, with less than a quarter remaining as wildlands, supporting just 11% of terrestrial net primary production. Anthropogenic biomes offer a new way forward by acknowledging human influence on global ecosystems and moving us toward models and investigations of the terrestrial biosphere that integrate human and ecological systems.

1,452 citations

Journal ArticleDOI
TL;DR: The herb layer has a significance that belies its diminutive stature and can provide important information regarding the site characteristics of forests, including patterns of past land-use practices.
Abstract: Despite a growing awareness that the herbaceous layer serves a special role in maintaining the structure and function of forests, this stratum remains an underappreciated aspect of forest ecosystems. In this article I review and synthesize information concerning the herb layer's structure, composition, and dynamics to emphasize its role as an integral component of forest ecosystems. Because species diversity is highest in the herb layer among all forest strata, forest biodiversity is largely a function of the herb-layer community. Competitive interactions within the herb layer can determine the initial success of plants occupying higher strata, including the regeneration of dominant overstory tree species. Furthermore, the herb layer and the overstory can become linked through parallel responses to similar environmental gradients. These relationships between strata vary both spatially and temporally. Because the herb layer responds sensitively to disturbance across broad spatial and temporal scal...

929 citations

Journal ArticleDOI
TL;DR: The interaction of the cultivation legacy with inherent soil and vegetation characteristics will determine the dynamics of plant community assembly on old fields and indicate the level of effort required to restore historical vegetation states.
Abstract: Environmental and socio-economic changes are leading to increased levels of land abandonment worldwide. The assembly of plant communities on old fields has informed much ecological theory, which in turn has facilitated efforts at ecological restoration. The interaction of the cultivation legacy with inherent soil and vegetation characteristics will determine the dynamics of plant community assembly on old fields and indicate the level of effort required to restore historical vegetation states. The abandonment of traditional agricultural lands in some areas will create old fields that require limited or no restoration. Yet intensification of agriculture and rapid environmental change will lead to increasing numbers of old fields that show little recovery towards an historic vegetation state. The restoration of these old fields will pose significant scientific and policy challenges.

756 citations

Journal ArticleDOI
TL;DR: This article proposed six hypotheses about local to continental effects of urbanization and pollution, and an operational research approach to test them, focusing on analysis of megapolitan areas that have emerged across North America, but also including diverse wildland-to-urban gradients and spatially continuous coverage of land change.
Abstract: Urbanization, an important driver of climate change and pollution, alters both biotic and abiotic ecosystem properties within, surrounding, and even at great distances from urban areas. As a result, research challenges and environmental problems must be tackled at local, regional, and global scales. Ecosystem responses to land change are complex and interacting, occurring on all spatial and temporal scales as a consequence of connectivity of resources, energy, and information among social, physical, and biological systems. We propose six hypotheses about local to continental effects of urbanization and pollution, and an operational research approach to test them. This approach focuses on analysis of “megapolitan” areas that have emerged across North America, but also includes diverse wildland-to-urban gradients and spatially continuous coverage of land change. Concerted and coordinated monitoring of land change and accompanying ecosystem responses, coupled with simulation models, will permit robust foreca...

648 citations


Cites background from "The Importance of Land-Use Legacies..."

  • ...Historical resources are of particular value, as many cur rent dynamics and future responses are conditioned by ecological legacies (eg soil, vegetation, biotic patterns and processes) resulting from past human or natural changes (Foster et al. 2003; Lewis et al. 2006)....

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Journal ArticleDOI
TL;DR: The role of agroforestry systems can play an important role in biodiversity conservation in human-dominated landscapes and alleviating resource-use pressure on conservation areas is examined.
Abstract: As rates of deforestation continue to rise in many parts of the tropics, the international conservation community is faced with the challenge of finding approaches which can reduce deforestation and provide rural livelihoods in addition to conserving biodiversity. Much of modern-day conservation is motivated by a desire to conserve 'pristine nature' in protected areas, while there is growing recognition of the long-term human involvement in forest dynamics and of the importance of conservation outside protected areas. Agroforestry - intentional management of shade trees with agricultural crops - has the potential for providing habitats outside formally protected land, connecting nature reserves and alleviating resource-use pressure on conservation areas. Here we examine the role of agroforestry systems in maintaining species diversity and conclude that these systems can play an important role in biodiversity conservation in human-dominated landscapes.

637 citations

References
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Journal ArticleDOI
TL;DR: In this article, a model of soil organic matter (SOM) quantity and composition was used to simulate steady-state organic matter levels for 24 grassland locations in the U.S. Great Plains.
Abstract: We analyzed climatic and textural controls of soil organic C and N for soils of the U.S. Great Plains. We used a model of soil organic matter (SOM) quantity and composition to simulate steady-state organic matter levels for 24 grassland locations in the Great Plains. The model was able to simulate the effects of climatic gradients on SOM and productivity. Soil texture was also a major control over organic matter dynamics. The model adequately predicted above-ground plant production and soil C and N levels across soil textures (sandy, medium, and fine); however, the model tended to overestimate soil C and N levels for fine textured soil by 10 to 15%. The impact of grazing on the system was simulated and showed that steady-state soil C and N levels were sensitive to the grazing intensity, with soil C and N levels decreasing with increased grazing rates. Regional trends in SOM can be predicted using four site-specific variables, temperature, moisture, soil texture, and plant lignin content. Nitrogen inputs must also be known. Grazing intensity during soil development is also a significant control over steady-state levels of SOM, and since few data are available on presettlement grazing, some uncertainty is inherent in the model predictions

3,594 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe ways in which excess nitrogen from fossil fuel combustion may stress the biosphere, and the complexity of these effects on water quality and on forest nutrition is discussed.
Abstract: This article describes ways in which excess nitrogen from fossil fuel combustion may stress the biosphere. Nitrogen emissions can have a direct effect on air quality through both the oxidizing potential of nitrogen oxides and the role these compounds play in the formation of ozone. The complexity of these effects on water quality and on forest nutrition is discussed.

2,333 citations

Journal ArticleDOI
TL;DR: In the US, nitrogen deposition remains relatively constant in the northeastern United States and is increasing in the Southeast and the West (Fenn et al. as mentioned in this paper, 2003), while acid acid deposition is increasing.
Abstract: N itrogen emissions to the atmosphere due to human activity remain elevated in industrialized regions of the world and are accelerating in many developing regions (Galloway 1995). Although the deposition of sulfur has been reduced over much of the United States and Europe by aggressive environmental protection policies, current nitrogen deposition reduction targets in the US are modest. Nitrogen deposition remains relatively constant in the northeastern United States and is increasing in the Southeast and the West (Fenn et al. in press). The US acid deposition effects

1,734 citations

Journal ArticleDOI
TL;DR: A montane grassland restoration project in northern New Mexico is described that was justified and guided by an historical sequence of aerial photographs showing progressive tree invasion during the 20th century, and a south- western network of fire histories illustrates the power of aggregating historical time series across spatial scales.
Abstract: Applied historical ecology is the use of historical knowledge in the man- agement of ecosystems. Historical perspectives increase our understanding of the dynamic nature of landscapes and provide a frame of reference for assessing modern patterns and processes. Historical records, however, are often too brief or fragmentary to be useful, or they are not obtainable for the process or structure of interest. Even where long historical time series can be assembled, selection of appropriate reference conditions may be com- plicated by the past influence of humans and the many potential reference conditions encompassed by nonequilibrium dynamics. These complications, however, do not lessen the value of history; rather they underscore the need for multiple, comparative histories from many locations for evaluating both cultural and natural causes of variability, as well as for characterizing the overall dynamical properties of ecosystems. Historical knowledge may not simplify the task of setting management goals and making decisions, but 20th century trends, such as increasingly severe wildfires, suggest that disregarding history can be perilous. We describe examples from our research in the southwestern United States to illustrate some of the values and limitations of applied historical ecology. Paleoecological data from packrat middens and other natural archives have been useful for defining baseline conditions of vegetation communities, determining histories and rates of species range expansions and contractions, and discriminating between natural and cultural causes of environmental change. We describe a montane grassland restoration project in northern New Mexico that was justified and guided by an historical sequence of aerial photographs showing progressive tree invasion during the 20th century. Likewise, fire scar chronologies have been widely used to justify and guide fuel reduction and natural fire reintroduction in forests. A south- western network of fire histories illustrates the power of aggregating historical time series across spatial scales. Regional fire patterns evident in these aggregations point to the key role of interannual lags in responses of fuels and fire regimes to the El Nino-Southern Oscillation (wet/dry cycles), with important implications for long-range fire hazard fore- casting. These examples of applied historical ecology emphasize that detection and expla- nation of historical trends and variability are essential to informed management.

1,372 citations

Journal ArticleDOI
TL;DR: It is concluded that natural variability concepts provide a framework for improved un- derstanding of ecological systems and the changes occurring in these systems, as well as for evaluating the consequences of proposed management actions.
Abstract: Natural resource managers have used natural variability concepts since the early 1960s and are increasingly relying on these concepts to maintain biological diversity, to restore ecosystems that have been severely altered, and as benchmarks for assessing anthropogenic change. Management use of natural variability relies on two concepts: that past conditions and processes provide context and guidance for managing ecological systems today, and that disturbance-driven spatial and temporal variability is a vital attribute of nearly all ecological systems. We review the use of these concepts for managing ecological systems and landscapes. We conclude that natural variability concepts provide a framework for improved un- derstanding of ecological systems and the changes occurring in these systems, as well as for evaluating the consequences of proposed management actions. Understanding the history of ecological systems (their past composition and structure, their spatial and temporal variability, and the principal processes that influenced them) helps managers set goals that are more likely to maintain and protect ecological systems and meet the social values desired for an area. Until we significantly improve our understanding of ecological systems, this knowledge of past ecosystem functioning is also one of the best means for predicting impacts to ecological systems today. These concepts can also be misused. No a priori time period or spatial extent should be used in defining natural variability. Specific goals, site-specific field data, inferences derived from data collected elsewhere, simulation models, and explicitly stated value judg- ment all must drive selection of the relevant time period and spatial extent used in defining natural variability. Natural variability concepts offer an opportunity and a challenge for ecologists to provide relevant information and to collaborate with managers to improve the management of ecological systems.

1,104 citations