74 research outputs found
Deserts and Desertification
A desert is an ecosystem in an arid zone in which sand dunes cover the land and sandstorms often occur. Although desert vegetation is sparse, it plays an important role in ecosystem structure and function. Desertification is one of the most severe environmental problems today. Land desertification can be controlled through many measures, such as eco-villages, eco-agriculture, biodiversity conservation, and the combination of engineering and biology. This edited volume provides new insights into the pattern of desert ecosystems and the progress of desertification control. It is a useful resource for researchers in ecology, forestry, and land desertification control
Integrated Applications of Geo-Information in Environmental Monitoring
This book focuses on fundamental and applied research on geo-information technology, notably optical and radar remote sensing and algorithm improvements, and their applications in environmental monitoring. This Special Issue presents ten high-quality research papers covering up-to-date research in land cover change and desertification analyses, geo-disaster risk and damage evaluation, mining area restoration assessments, the improvement and development of algorithms, and coastal environmental monitoring and object targeting. The purpose of this Special Issue is to promote exchanges, communications and share the research outcomes of scientists worldwide and to bridge the gap between scientific research and its applications for advancing and improving society
Linkages between Atmospheric Circulation, Weather, Climate, Land Cover and Social Dynamics of the Tibetan Plateau
The Tibetan Plateau (TP) is an important landmass that plays a significant role in both regional and global climates. In recent decades, the TP has undergone significant changes due to climate and human activities. Since the 1980s anthropogenic activities, such as the stocking of livestock, land cover change, permafrost degradation, urbanization, highway construction, deforestation and desertification, and unsustainable land management practices, have greatly increased over the TP. As a result, grasslands have undergone rapid degradation and have altered the land surface which in turn has altered the exchange of heat and moisture properties between land and the atmosphere. But gaps still exist in our knowledge of land-atmosphere interactions in the TP and their impacts on weather and climate around the TP, making it difficult to understand the complete energy and water cycles over the region. Moreover, human, and ecological systems are interlinked, and the drivers of change include biophysical, economic, political, social, and cultural elements that operate at different temporal and spatial scales. Current studies do not holistically reflect the complex social-ecological dynamics of the Tibetan Plateau. To increase our understanding of this coupled human-natural system, there is a need for an integrated approach to rendering visible the deep interconnections between the biophysical and social systems of the TP. There is a need for an integrative framework to study the impacts of sedentary and individualized production systems on the health and livelihoods of local communities in the context of land degradation and climate change. To do so, there is a need to understand better the spatial variability and landscape patterns in grassland degradation across the TP. Therefore, the main goal of this dissertation is to contribute to our understanding of the changes over the land surface and how these changes impact the plateau\u27s weather, climate, and social dynamics. This dissertation is structured as three interrelated manuscripts, which each explore specific research questions relating to this larger goal. These manuscripts constitute the three primary papers of this dissertation. The first paper documents the significant association of surface energy flux with vegetation cover, as measured by satellite based AVHRR GIMMS3g normalized difference vegetation index (NDVI) data, during the early growing season of May in the western region of the Tibetan Plateau. In addition, a 1°K increase in the temperature at the 500 hPa level was observed. Based on the identified positive effects of vegetation on the temperature associated with decreased NDVI in the western region of the Tibetan Plateau, I propose a positive energy process for land-atmosphere associations. In the second paper, an increase in Landsat-derived NDVI, i.e., a greening, is identified within the TP, especially during 1990 to 2018 and 2000 to 2018 time periods. Larger median growing season NDVI change values were observed for the Southeast Tibet shrublands and meadows and Tibetan Plateau Alpine Shrublands and Meadows grassland regions, in comparison to the other three regions studied. Land degradation is prominent in the lower and intermediate hillslope positions in comparison to the higher relative topographic positions, and change is more pronounced in the eastern Southeast Tibet shrublands and meadows and Tibetan Plateau Alpine Shrublands and Meadows grasslands. Geomorphons were found to be an effective spatial unit for analysis of hillslope change patterns. Through the extensive literature review presented in third paper, this dissertation recommends using critical physical geography (CPG) to study environmental and social issues in the TP. The conceptual model proposed provides a framework for analysis of the dominant controls, feedback, and interactions between natural, human, socioeconomic, and governance activities, allowing researchers to untangle climate change, land degradation, and vulnerability in the Tibetan Plateau. CPG will further help improve our understanding of the exposure of local people to climate and socio-economic and political change and help policy makers devise appropriate strategies to combat future grassland degradation and to improve the lives and strengthen livelihoods of the inhabitants of the TP
Effects of land-use change on grassland ecosystem services in Inner Mongolia and their implications for livelihoods and sustainable management
Grassland degradation has become a major challenge in many parts of the world, especially in arid or semi-arid areas, such as the Chinese Inner Mongolian Autonomous Region (IMAR). Previous studies of the grassland ecosystems in IMAR focused on climate change and its environmental consequences or on the land-use conflicts between agrarian communities and nomads. For better planning and management, a more integrated analysis of the consequences of land-use change for the livelihood dependence and other benefits (services) of the grasslands in IMAR is needed. Studies on ecosystem services of IMARâs grasslands are usually based on remote sensing data (TM images) to assess the total value of the grassland ecosystem services using benefit transfer. Thus far, to my knowledge no study collected original data on the detailed use of ecosystem services by pastoralists on the Mongolian Plateau or on their livelihood dependence on these services at the household level. Also, no data is available on the changes over time in contrasting situations for different grassland types (like meadow, steppe and desert steppe). I therefore aim to analyse the interactions between the people and the ecosystems in IMAR in an integrated manner, and especially focus on analysing the different utilization patterns of ecosystem services and the livelihood dependence of local herders and other stakeholders in selected study sites. The ultimate goal of my study is to contribute to sustainable management of the IMARâs ecosystems. To achieve the goal of my PhD study, the changes in land use, household consumption patterns and their impacts have been addressed and investigated for four selected study sites: Hulun Buir, Xilin Gol, Ordos and Alxa Right. These sites are in a âtransectâ from southwest to northeast to capture the gradient in use of ecosystem services in IMAR. The methodological framework of this research combines quantitative and qualitative tools to analyse ecosystem services. It specifies an integrative approach in specific spatial and temporal contexts to evaluate trade-offs between human activities, use of ecosystem services and human well-being. This framework enables to analyse the effects of multiple factors (e.g. policies or climate and geographic conditions) on utilization patterns of ecosystem services and the influence on society. The data used to apply the framework stems from a bottom-up approach by using household surveys and other local field data. The results show that the householdersâ intake comprised a low amount of crops, including staple foods, vegetables and fruit with a high amount of meat. However, more crops and less meat are increasingly preferred now. From 1995 to 2010, fuel consumption patterns changed from bio-fuels (especially dung) to mainly electricity and gas. Beside the influences of different environmental conditions and economic development, the grassland restoration policy measures changed grazing activities and basic household consumption patterns. Grazing activities were less affected by seasonal grazing and rotational grazing measures than other policy measures. However, when grazing was prohibited, immigration and livestock rearing control policy measures (e.g. in Xilin Gol and Ordos) fundamentally changed the basic household consumption patterns (especially for food and fuel). Livelihoodâs food-consumption highly links to potential water consumption. The results show that compared to the direct water consumption, the indirect water consumption through food production was a major share of total water consumption. From 1995 to 2010, indirect water consumption decreased in Xilin Gol and Ordos because meat consumption decreased and fruit and vegetable consumption increased. The grassland ecosystem degradation in IMAR leads to a shortage of meat production and this causes people to purchase food from outside, but the ability to purchase food also depends on income levels. The implementation of the grassland conservation policies significantly affected household livelihoods and this in turn, affected household use of natural assets (primarily the land), their agricultural assets (farming and grazing activities) and their financial assets (income and consumption). The households developed adaptation measures to account for the dependence of their livelihoods on local ecosystems by initializing strategies (e.g. seeking off-farm work, leasing pasture land, increasing purchases of fodder for stall-fed animals and altering their diet and fuel consumption) to compensate for their changing livelihoods. In general, the household dependence on local grasslands decreased. This indicates a transition from traditional pastoral grazing to control grazing, rising of modern dairy cattle (intensive animal husbandry), diversification of income sources and decreases in land-based employment and in the household food and fuel consumption. These changes increased the diversity of livelihoods, household resilience and environmental sustainability. Five grassland utilization patterns were identified, including no use (natural grasslands), light use, moderate use, intensive use and recovery sites (degraded sites protected from further use). The results show that light use generally provided higher levels of ecosystem services than intensive use and no use. Only supporting ecosystem services differed. Surprisingly, I found no consistently positive effects of the strict conservation activities across the sites, since the results varied spatially and with respect to differences in the land-use patterns. My results suggest that appropriate grassland-utilization patterns likely enhance the supply of ecosystem services and reduce negative effects on both household livelihoods and the environment. For example, in the Hulun Buir grasslands, the precipitation is 50% higher than in the other areas. Therefore the area tolerates a higher grazing intensity before degradation occurs and its grasslands provide more provisioning services but at the cost of decreased regulating and supporting services. After implementing grassland conservation policies, income from cultivation and animal grazing decreased, whereas income from compensation and off-farm activities increased. The herders preferred an annual payment of 99.2 US ha-1, resulting in an annual gap of 15.4 US$ ha-1. These currently too low payments probably lead some herders to expand their grazing into restricted grasslands or increase their number of animals, particularly if such payment program ends. To create an improved and sustainable payment scheme, solutions are needed that enable the herders to sustain their livelihood, while conserving the grasslands. My findings can help to establish appropriate grassland-utilization patterns and more effective payment schemes for the grasslands of IMAR and similar regions.</p
INVESTIGATING THE IMPACTS OF ANTHROPOGENIC AND CLIMATIC CHANGES ON THE STEPPE ECOSYSTEM IN CHINAâS LOESS PLATEAU AND THE MIXED-GRASS PRAIRIE REGION IN SOUTHWEST OKLAHOMA, USA
Grassland ecosystems occupy approximately 40% of the earthâs terrestrial area and represent one of most important ecosystems on Earth in terms of its impacts on global food supply, carbon sequestration and maintaining biodiversity. Grassland ecosystems are very sensitive to disturbances caused by either climatic or anthropogenic changes such as changes in precipitation regimes or management practices. The objective of this dissertation is to investigate the impacts imposed by grassland restoration activities and changes in precipitation anomalies on the steppe in Chinaâs Loess Plateau and the mixed-grass prairie in southwest Oklahoma. In chapter two, I analyzed how large-scale vegetation conservation programs affected the grassland dynamics in Chinaâs Loess Plateau by combining remotely sensed data with socio-economic statistics. The results of this study showed that the impact of vegetation conservation programs on vegetation change in the Loess Plateau is twofold. On the one hand, vegetation conservation programs target marginal lands. Thus, significant vegetation increases due to cropland conversion and afforestation can be found in these regions. On the other hand, intensified agricultural production can be found in croplands with suitable topography and well-established irrigation systems which were not enrolled in conservation programs to offset the agricultural production loss caused by vegetation conservation programs elsewhere. In chapter three, I demonstrated a new methodology on mapping the historical distribution of grassland species in southwest Oklahoma based on the Random Forest classification algorithm. In this study, elevation, soil pH and soil clay content were found to be significant variables for predicting the distribution of C3 and C4 grassland species. With the mapped distribution of grassland species between 1981 and 2010, in chapter four, I examined the relationship between changes in precipitation anomalies and the dynamics of relative abundance of C3 and C4 grassland species in southwest Oklahoma. In this study, significant decreases of C3/C4 ratio were identified in pasture/hay fields due to the increases in C4 abundance resulting from the decreases of sparsely vegetated area between 2005 and 2010. I suspect that the increase in C4 abundance was a drought adaptation strategy adopted by ranchers. Because C4 species are more tolerant of drought conditions and thus can help to maintain stable forage/hay production when negative precipitation anomalies prevailed during the growing season of C3 species
Environmental controls, morphodynamic processes, and ecogeomorphic interactions of barchan to parabolic dune transformations
The transformation of barchans into parabolic dunes has been observed in various dune systems around the world. Precise details of how environmental controls influence the dune transformation and stabilisation mechanism, however, remain poorly understood. A âhorns-anchoringâ mechanism and a ânebkhas-initiationâ mechanism have previously been proposed and selected environmental controls on the transformation have been explored by some modelling efforts, but the morphodynamic processes and eco-geomorphic interactions involved are unclear and comparison between different dune systems is challenging. This study extends a cellular automaton model, informed by empirical data from fieldwork and remote sensing, to fully explore how vegetation characteristics, boundary conditions, and wind regime influence the transformation process and the resulting dune morphologies. A âdynamic growth functionâ is introduced for clump-like perennials to differentiate between growing and non-growing seasons and to simulate the development of young plants into mature plants over multiple years. Modelling results show that environmental parameters interact with each other in a complex manner to impact the transformation process. The study finds a fundamental power-law relation between a non-dimensional parameter group, so-called the âdune stabilising indexâ (Sâ), and the normalised migration distance of the transforming dune, which can be used to reconstruct paleo-environmental conditions and monitor the impacts of changes in climate or land-use on a dune system. Four basic eco-geomorphic interaction zones are identified which bear different functionality in the barchan to parabolic dune transformation. The roles of different environmental controls in changing the eco-geomorphic interaction zones, transforming processes, and resulting dune morphologies are also clarified
Desertification
IPCC SPECIAL REPORT ON CLIMATE CHANGE AND LAND (SRCCL)
Chapter 3: Climate Change and Land: An IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystem
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