Dryland ecosystems cover 41% of Earth's land surfaces, account for 44% of cultivated lands and 60% of food sources, and make large contributions to the global water and carbon cycles. However, these ecosystems are experiencing unprecedented extremes including heatwaves, floods, and droughts as well as hotter temperatures and often declining water resource availability. These ecosystems are some of the most challenging to monitor given their high temporal variability with rapid response to their environment as well as vast spatial variability with intermixing of different plant species and life forms amongst bare soil coverage. The Adaptation and Response in Drylands (ARID) campaign was selected by National Aeronautics and Space Administration (NASA) as a scoping study to develop a research agenda for a dryland field campaign. Here, we detail our ARID science research agenda and implementation plan that were developed based on an extensive community engagement effort in over 160 events with over a thousand scientists, land managers, and Tribal communities between 2023 and 2024. The selected science themes cover drought and climate variability, ecosystem structure, function, and biodiversity, carbon cycle interannual variability and trends, and social ecological systems (land management and adaptation). We then detail our remote sensing, modeling, and field-based strategies to capture high temporal and high spatial resolution processes. Finally, our implementation strategy is presented which includes focus area selections in a core intensive western U.S. domain and distributed international domains. This strategy includes our overarching guiding principles of using multi-temporal airborne acquisitions and super sites as well as enhancing land management in co-development with end-user partners. While originally developed for NASA, our ARID report creates a blueprint for any future dryland field campaign, at any scale, that can be implemented widely for foundational and applied science objectives.

Drylands cover 41% of Earth's land surface, support 36% of the global population and contribute 60% of global food production. Despite these ecosystems' importance and high vulnerability to droughts and heatwaves, drylands remain some of the most understudied systems on Earth. Monitoring drylands is challenging due to their complex ecosystem structure of visible soil mixed with diverse plant species that respond rapidly to weather and climate. In 2023 and 2024, a NASA scoping study was conducted for a proposed dryland terrestrial ecology field campaign called Adaptation and Response in Drylands (ARID). Thereafter, the NASA ARID scoping team submitted their campaign proposal to NASA Headquarters, providing a study design for how field, aircraft and satellite measurements, as well as modeling, could address the most critical fundamental and applied science questions in drylands. The extensive strategic vision was created by and for the drylands research community, including remote sensors, modelers, experimentalists and ecologists from across the world, and the overall approach can be further utilized and altered for different uses and data information needs. Here, we summarize the final ARID research agenda, including its main objectives, field campaign strategy, data end-user support strategy, and U.S. and global community engagement.

Global terrestrial ecosystems exhibit substantial interannual variability (IAV) in net carbon (C) flux. Determining the biogeographic origin of this variability is essential for the understanding and forecasting of global C cycling and carbon-climate feedbacks. Currently, most studies identify either global drylands or moist tropical forests as the dominant source of IAV. Considering this, we investigated whether the use of three different global ecosystem classifications of drylands and moist tropical forests, as well as two alternative geographical scales, could alter which ecosystem is the dominant contributor to terrestrial net C flux IAV. Using the simulation results of 18 dynamic global vegetation models from the TRENDY v11 model intercomparison, we calculated the absolute and area-weighted contributions of net C flux IAV for: individual 0.5° grid cells, global ecosystem classifications, and ecoregions (intermediate scale between grid cells and global ecosystems). For all three of the global ecosystem classification schemes, we found the drylands IAV contributions of 41%, 32%, and 37% were significantly greater than the associated IAV contributions of 20%, 19%, and 24% from the moist tropical forests ( p < 0.001). However, the moist tropical forests had a higher IAV contribution per unit area across all three classification schemes (∼3% versus ∼1%–2% ( p < 0.001)). At the ecoregion scale, this switch between drylands and moist tropical forests was absent; as seven of the ten highest absolute and nine of the ten highest area-weighted contributing ecoregions were drylands. Specifically, we found tropical and subtropical grasslands, savannas, and shrublands to be particularly substantial contributors to global terrestrial net C flux IAV, with the Cerrado’s absolute IAV contribution of 3.52% exceeding all but one of the other 763 global ecoregions IAV contributions (all p < 0.05). Our findings demonstrate that drylands persist as the dominant contributor to global terrestrial net C flux IAV, irrespective of different global ecosystem classifications or geographic scales.

AbstractAmerican drylands account for circa 20% of the global drylands and form a critical part of the global ecosystems. This study comprehensively assessed the ecology and socio-economic status of American drylands by analyzing original and published data. The research findings reveal that North and South American drylands have more differences than commonness. In terms of commonness, both North and South American drylands have higher productivity and soil fertility than other drylands of the globe. Under this high ecosystem productivity context, North American drylands are the high agricultural productivity regions and South America is the largest beef exporter in the world. There are several aspects of differences between North and South American drylands. North American drylands possess an ecosystem productivity twice that of South American drylands. Precipitation has significantly decreased in North America drylands, while South American drylands have become wetting over the past three decades. Population in both North and South American drylands have increased. Vegetation coverage trends exhibit a weak rising trend in South America, while North America drylands have become significantly greener, mainly due to croplands irrigation. The driving forces on land use change and ecosystem productivity in North American drylands comprise a variety of factors, while those on South American drylands are relatively simpler, mostly caused by one driving agent. In dealing with the dual pressures of climate change and socio-economic developments, countries in both North and South America have implemented a series of drylands ecosystem protection measures, such as setting national park and conservation agriculture. These efficient and successful experiences can be examples for other dryland ecosystem protection around the world.

Abstract Dryland ecosystems cover 40% of our planet's land surface, support billions of people, and are responding rapidly to climate and land use change. These expansive systems also dominate core aspects of Earth's climate, storing and exchanging vast amounts of water, carbon, and energy with the atmosphere. Despite their indispensable ecosystem services and high vulnerability to change, drylands are one of the least understood ecosystem types, partly due to challenges studying their heterogeneous landscapes and misconceptions that drylands are unproductive “wastelands.” Consequently, inadequate understanding of dryland processes has resulted in poor model representation and forecasting capacity, hindering decision making for these at‐risk ecosystems. NASA satellite resources are increasingly available at the higher resolutions needed to enhance understanding of drylands' heterogeneous spatiotemporal dynamics. NASA's Terrestrial Ecology Program solicited proposals for scoping a multi‐year field campaign, of which Adaptation and Response in Drylands (ARID) was one of two scoping studies selected. A primary goal of the scoping study is to gather input from the scientific and data end‐user communities on dryland research gaps and data user needs. Here, we provide an overview of the ARID team's community engagement and how it has guided development of our framework. This includes an ARID kickoff meeting with over 300 participants held in October 2023 at the University of Arizona to gather input from data end‐users and scientists. We also summarize insights gained from hundreds of follow‐up activities, including from a tribal‐engagement focused workshop in New Mexico, conference town halls, intensive roundtables, and international engagements.

The Bulletin of the Ecological Society of America is the official record of business of the Ecological Society of America, publishing non-refereed articles that cover ecological events, news and reports.

Land use is central to addressing sustainability issues, including biodiversity conservation, climate change, food security, poverty alleviation, and sustainable energy. In this paper, we synthesize knowledge accumulated in land system science, the integrated study of terrestrial social-ecological systems, into 10 hard truths that have strong, general, empirical support. These facts help to explain the challenges of achieving sustainability in land use and thus also point toward solutions. The 10 facts are as follows: 1) Meanings and values of land are socially constructed and contested; 2) land systems exhibit complex behaviors with abrupt, hard-to-predict changes; 3) irreversible changes and path dependence are common features of land systems; 4) some land uses have a small footprint but very large impacts; 5) drivers and impacts of land-use change are globally interconnected and spill over to distant locations; 6) humanity lives on a used planet where all land provides benefits to societies; 7) land-use change usually entails trade-offs between different benefits-"win-wins" are thus rare; 8) land tenure and land-use claims are often unclear, overlapping, and contested; 9) the benefits and burdens from land are unequally distributed; and 10) land users have multiple, sometimes conflicting, ideas of what social and environmental justice entails. The facts have implications for governance, but do not provide fixed answers. Instead they constitute a set of core principles which can guide scientists, policy makers, and practitioners toward meeting sustainability challenges in land use.

A summary of Symposium 2, held at the 2021 ESA Annual Meeting Part 1. Looking Beyond Stockholm +50: The Ecological Science: What have we learned and How is ecology being applied Part 2. Looking Beyond Stockholm +50: Moving toward Solutions: System Approaches to Sustaining Human-environment systems The first United Nations conference on the Human Environment was held in Stockholm, Sweden June 1972. This 1972 conference set the stage for international and national efforts to reduce human-driven activities resulting in pollution of the air, water, and land; destruction of irreplaceable natural resources; and the degradation of the environment’s capacity to support life and societies around the world. In article 6, the UN report states that: “For the purpose of attaining freedom in the world of nature, man must use knowledge to build, in collaboration with nature, a better environment … for present and future generations…”. In essence, this conference began to document the human actions that together are a signature of the Anthropocene. The Stockholm Conference initiated a call for action to improve the stewardship of our planet. The outcome of the Stockholm Conference was an ambitious agenda to guide nations to deal with a complex array of global environmental challenges as well as to design pathways toward sustainable development to improve human well-being and restore nature. These challenges are far from being met although we have made progress in a number of these areas. The research community in partnership with decision-makers and practitioners is committed to the development of strategies among nations to envision sustainable development pathways that would improve the human-environment relationship to restore the biosphere and natural capital that supports society. Our symposium was designed to recognize scientific advances but to also identify solutions to these and emerging human-environmental challenges that are on the horizon. Our speakers were as follows: F. Stuart Chapin, III (Institute of Arctic Biology, University of Alaska Fairbanks); Paty Romero-Lankao (DOE-National Renewable Energy Laboratory); Moffat Ngugi (US-AID); and Richard Moss (Pacific Northwest National Laboratory – Joint Global Change Research Institute). Associated with the symposium was a companion Special Session that focused on the state of research to address the challenges society is currently contending with and how these can be used to inform decision-makers and practitioners. The panelists contributing to the special session were as follows: Gretchen Daily (Stanford Woods Institute for the Environment, Stanford University); Patrick Keys (School of Global Environmental Sustainability, Colorado State University); James Randerson (Earth System Science, University of California, Irvine); David Schimel (NASA-Jet Propulsion Laboratory). Topics covered included; aspects of stewardship, collaborative efforts, urban sustainability, food security, carbon cycle, water security, natural capital, and scales of challenges in space and time dealing with path dependencies and multi-century effects of global environmental change. Presentations and background material can be found at the 2021 Annual Meeting website until July 2022 (https://www.eventscribe.net/2021/ESA/index.asp). Across the two sessions, a set of common frameworks were invoked, such as the Planetary Boundaries (Rockström et al. 2009), to illustrate the environmental state of the earth system. Integrating social dimensions within the Planetary Boundaries was invoked by several speakers (Chapin, Keys, Moffat) through exploration of the “Donut Economy” (Raworth 2017) and InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs; https://naturalcapitalproject.stanford.edu/software/invest). There was a call for enhanced engagement with the social sciences and with practitioners, especially related to the coproduction of solutions (Moss). Speakers also elaborated on the need to integrate ecosystem services with livelihood goals in a way that develops more suitable actions (Chapin). The Global Ecosystem Product (GEP; Ouyang et al. 2020) was presented to illustrate novel methodologies to assess the state of natural capital and ecosystem services to decision-making (Daily). A topic that received considerable discussion in our session was nature-based solutions that integrate cultural and local knowledge systems in the development of solutions strategies related to food production (Moffat) and urban access to renewable energy (Romero-Lankao). Moss also called for the need to develop a platform to support knowledge sharing and creation to foster transformative changes using real-world experiences to shape these strategies and practices. All of the symposium’s participants recognized the need to reach out to the disenfranchised members of society to ensure greater equity and to reduce the harm of disproportionate access to ecosystem services and services to enhance well-being. Our Special Session panel members stressed the need for interdisciplinary approaches and systems analysis in support of expanding our understanding of the earth system and to provide insights on the complexity of the changes taking place. In addition, the panelists provided information regarding new advances in our science and assessment activities. Carbon issues were a central theme. The first point was that as we study the consequences of elevated CO2 affecting our climate, there is a need to look beyond the next century but also consider millennial consequences on the earth system and society in future (Randerson). A second issue raised by the panelists was related to the pernicious nature of CO2 behavior in response to reducing the atmospheric loading of the compound. The ocean and terrestrial ecosystems have stored extensive amounts of carbon in past 150 years in response to the rising availability of CO2 in the atmosphere. However, as we successfully reduce these levels in the coming decades, these natural sinks will respond by degassing CO2 from the oceans and respiring these from the terrestrial pools (Schimel). So the task of reducing atmosphere levels of CO2 as we work to stabilize the climate is made more difficult. Another common theme among all of the panelists and speakers is the urgency of taking action now and to engage in transdisciplinary approaches that pull together expertise and knowledge from appropriate sectors of society and science. We all acknowledge that the pace of change has continued to accelerate, but that the pace of finding sustainable solutions has also increased over the past decade. However, we also recognize that implementation of adaptation and mitigation strategies are not being applied evenly across the globe and that greater effort needs to be placed on serving the most vulnerable. Deployment of these solutions and access to emerging research knowledge needs to be shared to create a safe and just operating space (Keys). In summary, as we look forward into the coming decade, our panelists pointed to the need for joint efforts to develop an anticipatory research agenda that encompasses multifaceted scales of space and time, is multiculturally inclusive, and representative across sectors. This research agenda embraces the complexity of the times and interwoven nature of the issues we are facing throughout the globe. This research agenda must, therefore, be based on greater collaboration with the social sciences, as well as with other members of civil society. The solutions we develop should be equitable, sustainable, and accessible, so that a safe and just operating space is created. Solution science needs inclusion of members of not only the scientific and technocrats, but members of civil society and practitioners that have greater knowledge of the local needs and conditions. The coproduction of these solutions should be derived from experiential activities that are place-based and serve as a platform to share knowledge and skills, as well as to create new knowledge to deal with the “wicked problems” communities face. Going forward, it is critical to develop a training program in which the needed skill- and knowledge-sets are brought together in a way that allows for developing appropriate solutions at the granularity of the communities they are aimed to serve. Finding the resources to do this in a scalable fashion is an immediate need.

With the liftoff of the Landsat 1 satellite on July 23, 1972, the Landsat Program started a so far uninterrupted exploration of the Earth, which has – over the past 50 years – enabled ecologists to better understand rapid changes across terrestrial ecosystems on a global scale. According to Sam Goward, an early contributor to Landsat science, “it was the early vision in the late 1960s of William Pecora, then-director of USGS [US Geological Survey], and Stuart Udall, then-Secretary of the Interior, that led to the conceptual development of Landsat, which was launched by NASA [National Aeronautics and Space Administration]” (Goward et al. 2017). Little did they and the early developers at the time foresee the tremendous future success of the mission, its influence on subsequent ecological studies and resource decision making, and its operational lifetime of 50+ years, with the launch of Landsat 9 in 2021 and plans near approval for Landsat 10, both of which will extend the mission into the coming decades (Figure 1). “The Landsat mission almost never got started with its instrument of choice: when the preferred Return Beam Vidicon [RBV] sensor failed, and the more experimental Multispectral Scanner [MSS] proved to be a useful workhorse”, added Goward. The initial 79-m pixel resolution of the MSS observations by Landsats 1, 2, and 3 was upgraded with Thematic Mapper (TM) sensors coming online with Landsat 4 in 1982, thereby commencing the era of 30-m pixel observations, which continues to this day. At spatial scales useful to researchers and natural resource managers, those early observations provided the first opportunities to remotely detect widespread changes in land cover and to document global patterns of ecological features. Over the years, Landsat data products have been used to examine forest phenology, wetland spatial dynamics, land-cover conversions, disturbance patterns related to wildfires and storm effects, and efficacy of conservation efforts (Pasquarella et al. 2016). Resource managers and policy makers have relied on Landsat-derived analyses to highlight the rate of land-cover changes occurring in desired regions and to identify areas for further study and protection. Landsat-based observations have been an effective tool in monitoring deforestation rates in the Amazon Basin (Figure 2) and other tropical regions. Conservation groups and government agencies routinely depend on these datasets to evaluate policies related to biodiversity loss and global environmental change. For instance, concerns over uncertainties in rates of tropical deforestation in the Amazon Basin reported during the late 1980s led to one of the initial investigations of the Landsat Pathfinder Program (namely, the Humid Tropical Forest Inventory Project) in the early 1990s. Headed by David Skole and Compton Tucker, this early study (Skole and Tucker 1993) was able to pull together massive sets of Landsat data spanning the Brazilian Amazon between 1978 and 1988 to objectively quantify the decadal rate of deforestation across the region. Critical in characterizing the scope of Amazon deforestation rates during the 1980s and subsequent decades, these observations and analyses led to the Brazilian government recognizing the extent of deforestation taking place and pledging to reduce the rate of deforestation across the region. Matt Hansen (University of Maryland), current Landsat science team member, highlighted the importance of the Landsat Pathfinder Program, which changed how satellite images were selected. Before this time, documenting tropical forest coverage at sites in Central Africa and Southeast Asia required the acquisition of cloud-free observations, which was challenging. With the program’s implementation of a pixel selection process that rendered cloud-free composite images, the utility of the Landsat image archive in detecting deforestation in remote regions of the tropics was greatly enhanced, allowing for decadal land-cover change analyses (over the 1970–1980 and 1980–1990 periods). The 1990s also represented the era when Landsat data were increasingly utilized for conservation purposes, especially to investigate the encroachment of land conversion on protected areas. Early adopters of the 30-m Landsat TM data included researchers such as Andy Hansen (Montana State University) and Ruth DeFries (then with the University of Maryland). In collaboration with Warren Cohen (Oregon State University), Andy Hansen remarked that access to 30-m datasets was critical to address changes in the Greater Yellowstone Ecosystem and Yellowstone National Park (YNP). By quantifying changes in evergreen forest cover within the YNP and thereby having the ability to evaluate potential changes in the fragmentation of and carbon storage in the YNP’s forested areas, this research helped to advance our understanding of human pressures on a key ecosystem. In the late 1990s, DeFries and her colleagues combined Landsat analysis with global tree cover from Advanced Very High Resolution Radiometer (AVHRR) data to calibrate a carbon emissions product (DeFries and Townshend 1999). Following this, in 2008 Matt Hansen and his team used a combination of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and Landsat imagery to analyze forest conversion globally, developing a fused data product of the two sets of observations. This important application promoted efforts to automate the processing stream and exploit massive amounts of digital Landsat imagery and pixel selection (Hansen et al. 2013), which continues today as Global Forest Watch (www.globalforestwatch.org). As part of NASA’s Earth Observing System Project, these interdisciplinary studies enabled ecologists to study land-cover changes and evaluate climate and carbon-cycle changes affecting the Earth system. The launch of Landsat 7 in 1999 provided some additional upgrades with the inclusion of the Enhanced Thematic Mapper Plus (ETM+) sensor, which offered high spatial resolution with a panchromatic band and additional spectral bands, and maintained the continuity of core measurements. The Landsat 7 science team also developed several long-term procedures to integrate past Landsat observations with imagery from current and future missions. After more lenient data policies were introduced by USGS in 2008, an explosion in the use of Landsat data followed. Free and unrestricted access to the TM datasets allowed researchers to expand their studies of land-surface changes to larger regional domains over the period of data collection. Increased reliance on the Landsat data archive was also associated with the Analysis Ready Datasets (ARDs) created by the USGS Earth Resources Observation and Science (EROS) Data Center in 2018 and the ARD developed by the University of Maryland’s Global Land Analysis and Discovery laboratory in 2019. These datasets facilitate use by creating a spatially consistent, geometrically and atmospherically corrected, cloud-free data collection for the detection of land-cover change. Landsat data continue to be used and advanced by groups such as Jody Vogeler’s research team at Colorado State University. She and her colleagues are incorporating data from the recent spaceborne-lidar (light detection and ranging) mission – NASA’s Global Ecosystem Dynamics Investigation (GEDI) – along with Landsat and other Earth observations to characterize forest structure across broad spatial and temporal extents for a variety of applications. The synergistic use of lidar imagery of forest structure and topography around the world will enhance the interpretative power of the long-term data available through Landsat observations. Further collaborations with other (multi-)national initiatives, such as the Sentinel Program of the European Space Agency (the other ESA), are integrating Landsat’s long-term imagery with additional multispectral observations to advance our understanding of changes occurring across the Earth’s terrestrial surfaces. The Landsat mission continued its saga with the launch of Landsat 8 in 2013, which introduced next-generation Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) instruments (www.usgs.gov/landsat-missions/landsat-8). Likewise, Landsat 9 became operational in 2021 and plans for Landsat 10 are nearing completion, to ensure years of consistent, uninterrupted observations. The ecological community has greatly benefitted from the vision and fortitude of the researchers, developers, and mission managers to maintain this valuable set of observations, and we are grateful for their continued diligence in preserving the observations’ continuity while simultaneously making technological advancements. Any opinions, findings, and conclusions or recommendations expressed in this article are those of the authors and do not necessarily reflect the views of the USGS.

Weathers et al explains that disruptions like the lockdown implementation in response to the emerging COVID-19 pandemic have catapulted us into the "anthropause", providing a glimpse of how the Earth system rapidly adjusts to dramatic reductions in human activity. This anthropause is both a cultural and ecological inflection point. We now have a choice, which is to return to our pre-pandemic lives and livelihoods, or to leverage the anthropause to address ecological imbalances and injustices to change how, when, where, and with whom we create ecological knowledge. Meanwhile, three actions for bolstering social and ecological resilience, inspired by this unique moment in time, are suggested. These include bringing ecological knowledge to bear on complex problems, expanding and refocusing the lenses through which we view and practice ecology, and focusing on feedbacks within and among social and ecological systems.

National and international agencies and organizations have published reports outlining critical natural resource, environmental, and societal challenges facing global inhabitants. These reports include the UN Sustainability Goals, Future Earth, Global Land Project, and the Resilience Alliance. Recognizing many of the topics listed in these reports are broad and aspirational, the authors of this chapter have disaggregated many topics into research and management challenges for which the systems ecology paradigm is well suited. Disaggregation is based on challenges at different spatial hierarchical scales: organisms/populations; ecological sites; landscapes; small regions/watersheds; regions/nations; continents; and the globe. Emphasis is placed on research needs at landscape and larger hierarchical levels. Biophysical knowledge acquired during the past 50 years about organism/population and ecological site levels is available now to better manage ecosystems and natural resources. However, research blending the ecosystem knowledge base with behavioral, learning, organizational, and marketing sciences is vitally needed to affect management practice change at scales where people manage land and waters. The goal is to engage managers, policy makers, thought leaders, and concerned citizens to resolve critical problems and adopt best management practices to meet current and future environmental challenges (e.g., provision of ecosystem services and climate change effects on ecosystem).

The Great Plains region plays an important role in providing water and land resources and habitat for wildlife and livestock, crops, energy production, and other critical ecosystem services to support rural livelihoods. The semiarid conditions of the region and tight coupling of livelihood enterprises with ecosystem services creates a situation of increased sensitivity to climate changes and enhanced vulnerability among the rural communities and Native American nations across the region. Recent climate conditions associated with warming trends, and altered atmospheric flows have resulted in rapid onset of drought conditions and other extreme weather events across the region that are changing seasonal patterns of temperature and precipitation and warming trends. Projected climate changes provided in the fourth US National Climate Assessment indicate that potential warming and variability of precipitation will further increase drought and extreme weather events. Recent research and assessment efforts of current and projected climate changes in the Great Plains indicate that rural communities and ecosystems are becoming more vulnerable to changes associated with warming trends, droughts, and increased variability in precipitation. These climate changes are having differential impacts on ecosystem services that are critical to livelihood enterprises. Strategies for how resource managers and the research community can better collaborate and more effectively codesign and coproduce efforts to understand and to respond to these challenges are needed. (C) 2021 The Society for Range Management. Published by Elsevier Inc. All rights reserved.

The Northern Great Plains (NGP) region plays a very important role in providing water and land resources and other critical ecosystem services to support rural livelihoods. Semi-arid conditions and the tight coupling of livelihood enterprises with ecosystem services increases sensitivity to climate change. The changing climate and social-economic situations across the NGP have further challenged current management practices. Recent climate stresses has indicated that changing seasonality and extreme events (e.g., droughts, floods, ice storms) are impacting ecosystem services and increasing vulnerability to rural livelihoods. In particular, the emergence of rapid on-set of drought has been problematic to resource managers and operators due the shortened period to respond to these drought events. This paper provides a regional example for the North American Great Plains to illustrate how emerging climate impacts affect the ability to respond within the social-ecological system capabilities to manage for these impacts. This paper is a contribution to an international effort, the Global Dryland Ecosystem Programme (Fu et al. this issue), to develop regional research and engagement efforts to further understand the impacts of climate change on ecosystem processes and to enable this knowledge to guide further development of adaptive management options.

The systems ecology paradigm (SEP) emerged in the late 1960s at a time when societies throughout the world were beginning to recognize that our environment and natural resources were being threatened by their activities. Management practices in rangelands, forests, agricultural lands, wetlands, and waterways were inadequate to meet the challenges of deteriorating environments, many of which were caused by the practices themselves. Scientists recognized an immediate need was developing a knowledge base about how ecosystems function. That effort took nearly two decades (1980s) and concluded with the acceptance that humans were components of ecosystems, not just controllers and manipulators of lands and waters. While ecosystem science was being developed, management options based on ecosystem science were shifting dramatically toward practices supporting sustainability, resilience, ecosystem services, biodiversity, and local to global interconnections of ecosystems. Emerging from the new knowledge about how ecosystems function and the application of the systems ecology approach was the collaboration of scientists, managers, decision-makers, and stakeholders locally and globally. Today’s concepts of ecosystem management and related ideas, such as sustainable agriculture, ecosystem health and restoration, consequences of and adaptation to climate change, and many other important local to global challenges are a direct result of the SEP.

The evolution of ecosystem science and systems ecology as legitimate branches of science has occurred since the late 1960s. They have flourished because of their essential contributions to understanding and management of natural resources and the environment. Scientific knowledge about the structure and functioning of ecosystems, the services ecosystems provide to people, and the roles people play therein, have become commonplace. Scientists know what challenges face Earth’s environments and they know many of the solutions available to resolve them. But scientific knowledge alone is insufficient to implement change. Knowledge transfer to people who manage our lands, waters, and other natural resources is essential and they must become engaged in implementing solutions to major natural resource and environmental challenges. Adoption of new concepts and technologies is critical. Overcoming the barriers to adoption of best management practices is critically needed. Many of the barriers are created by adherence to dogmatic cultural norms and ideologies by landowners, managers, and policy makers. Behavioral, organizational, learning, and marketing professionals study behavioral change. The systems ecology paradigm must incorporate behavioral, organizational, learning, and marketing professionals as partners in implementing concepts of adoption cycles and community-based social marketing to solve wicked problems.

The problems of today cannot be solved by the level of thinking that caused them.

Ecosystem modeling, a pillar of the systems ecology paradigm (SEP), addresses questions such as, how much carbon and nitrogen are cycled within ecological sites, landscapes, or indeed the earth system? Or how are human activities modifying these flows? Modeling, when coupled with field and laboratory studies, represents the essence of the SEP in that they embody accumulated knowledge and generate hypotheses to test understanding of ecosystem processes and behavior. Initially, ecosystem models were primarily used to improve our understanding about how biophysical aspects of ecosystems operate. However, current ecosystem models are widely used to make accurate predictions about how large-scale phenomena such as climate change and management practices impact ecosystem dynamics and assess potential effects of these changes on economic activity and policy making. In sum, ecosystem models embedded in the SEP remain our best mechanism to integrate diverse types of knowledge regarding how the earth system functions and to make quantitative predictions that can be confronted with observations of reality. Modeling efforts discussed are the Century ecosystem model, DayCent ecosystem model, Grassland Ecosystem Model ELM, food web models, Savanna model, agent-based and coupled systems modeling, and Bayesian modeling.

Emerging from the warehouse of knowledge about terrestrial ecosystem functioning and the application of the systems ecology paradigm, exemplified by the power of simulation modeling, tremendous strides have been made linking the interactions of the land, atmosphere, and water locally to globally. Through integration of ecosystem, atmospheric, soil, and more recently social science interactions, plausible scenarios and even reasonable predictions are now possible about the outcomes of human activities. The applications of that knowledge to the effects of changing climates, human-caused nitrogen enrichment of ecosystems, and altered UV-B radiation represent challenges addressed in this chapter. The primary linkages addressed are through the C, N, S, and H2O cycles, and UV-B radiation. Carbon dioxide exchanges between land and the atmosphere, N additions and losses to and from lands and waters, early studies of SO2 in grassland ecosystem, and the effects of UV-B radiation on ecosystems have been mainstays of research described in this chapter. This research knowledge has been used in international and national climate assessments, for example the IPCC, US National Climate Assessment, and Paris Climate Accord. Likewise, the knowledge has been used to develop concepts and technologies related to sustainable agriculture, C sequestration, and food security.

This chapter discusses the soil organic matter (SOM) models have been used as tools to improve our understanding about nutrient cycling and SOM dynamics, and how these models have been used as policy and management tools to evaluate the long-term implication of different management practices. One of the difficulties encountered in studies of SOM dynamics has been the lack of a physical or chemical methods to isolate directly the various organic matter pools suggested by various decomposition studies. Field and model results suggest that the major impact of tillage on SOM dynamics isincreased decay rates due to stirring of the soil and alterations of soil microclimate which impacts the decomposition rate of the SOM pools. The direct effect of climatic change on plant production is to increase production for most regions with the exception of the extreme continental steppe regions where production decreased dramatically.

A Correction to this paper has been published: https://doi.org/ https://doi.org/10.1007/s10584-020-02948-3