Recent trends in vegetation greenness in China significantly altered annual evapotranspiration and water yield

There has been growing evidence that vegetation greenness has been increasing in many parts of the northern middle and high latitudes including China during the last three to four decades. However, the effects of increasing vegetation greenness particularly afforestation on the hydrological cycle have been controversial. We used a process-based ecosystem model and a satellite-derived leaf area index (LAI) dataset to examine how the changes in vegetation greenness affected annual evapotranspiration (ET) and water yield for China over the period from 2000 to 2014. Significant trends in vegetation greenness were observed in 26.1% of China\u27s land area. We used two model simulations driven with original and detrended LAI, respectively, to assess the effects of vegetation \u27greening\u27 and \u27browning\u27 on terrestrial ET and water yield. On a per-pixel basis, vegetation greening increased annual ET and decreased water yield, while vegetation browning reduced ET and increased water yield. At the large river basin and national scales, the greening trends also had positive effects on annual ET and had negative effects on water yield. Our results showed that the effects of the changes in vegetation greenness on the hydrological cycle varied with spatial scale. Afforestation efforts perhaps should focus on southern China with larger water supply given the water crisis in northern China and the negative effects of vegetation greening on water yield. Future studies on the effects of the greenness changes on the hydrological cycle are needed to account for the feedbacks to the climate

Three Essays in Forest Resource Management: Landowners’ Considerations in Ecosystem Services, Forest Certification, and Timber Supply

Forest ecosystems provide a wide range of timber and non-timber ecosystem services that play a vital role in supporting human health, well-being, and economy. Sustaining forest ecosystem will depend on landowners’ interest and willingness to responsibly manage forests, and provide timber and non-timber services for public benefit. Despite a substantial research in understanding how forest resources are managed by landowners, several literature gaps still exist regarding how landowners’ behavior/activities associated with sustaining the supply of ecosystem services and timber, and participating in best management practices such as forest certification. By applying methods grounded in economic and human dimension theory, this dissertation finds empirical evidences to answer key questions relevant in landowners’ perspectives in supply of timber and non-timber benefits and adoption of certification practices. The first essay investigates the interest of nonindustrial private forest (NIPF) landowners in managing their forests for provision of ecosystem services (carbon storage, water quality protection, and aesthetics) and summarizes the corresponding influencing factors by using the survey data collected from the Cumberland Plateau, Tennessee. The second essay analyzes the landowners’ perceived barriers and opportunities in adopting forest certification in China. Using a meta-analysis method, the third essay highlights how price responsiveness of timber supply responds to market price, and other factors representing landowners’ characteristics. The essays in this dissertation provide some insights in understanding the decision-making behavior of landowners relative to providing both timber and non-timber services and sustaining forest management. Findings add significantly to the forest economic and management literature. In addition, conceptual frameworks and estimation techniques adopted in some of these essays could be extended or improved upon in future studies

Impacts of climate change and human activities on vegetation coverage variation in mountainous and hilly areas in Central South of Shandong Province based on tree-ring

IntroductionIt is of great significance to understand the characteristics and influencing factors of vegetation coverage variation in the warm temperate zone. As a typical region of the warm temperate zone in eastern China, the mountainous and hilly region in central-south Shandong Province has fragile ecological environment and soil erosion problem. Studying on vegetation dynamics and its influencing factors in this region will help to better understand the relationship between climate change and vegetation cover change in the warm temperate zone of eastern China, and the influence of human activities on vegetation cover dynamics.MethodsBased on dendrochronology, a standard tree-ring width chronology was established in the mountainous and hilly region of central-south Shandong Province, and the vegetation coverage from 1905 to 2020 was reconstructed to reveal the dynamic change characteristics of vegetation cover in this region. Secondly, the influence of climate factors and human activities on the dynamic change of vegetation cover was discussed through correlation analysis and residual analysis.Results and discussionIn the reconstructed sequence, 23 years had high vegetation coverage and 15 years had low vegetation coverage. After low-pass filtering, the vegetation coverage of 1911–1913, 1945–1951, 1958–1962, 1994–1996, and 2007–2011 was relatively high, while the vegetation coverage of 1925–1927, 1936–1942, 2001–2003, and 2019–2020 was relatively low. Although precipitation determined the variation of vegetation coverage in this study area, the impacts of human activities on the change of vegetation coverage in the past decades cannot be ignored. With the development of social economy and the acceleration of urbanization, the vegetation coverage declined. Since the beginning of the 21st century, ecological projects such as Grain-for-Green have increased the vegetation coverage

Dynamics of land use and land cover changes in China

A key contribution of environmental economics to policy making has been to provide empirical indicators of sustainable economic development. An economy is (weakly) sustainable if it saves more than the combined depreciation of its stocks of natural capital and produced capital. Thus, these indicators allow trade-offs where, for example, natural capital might be depreciated in order to build up other forms of capital, such as in the built environment or in the form of human capital. As an application of this general idea, this thesis focuses on the trade-offs between ecosystem services, provided by natural capital, and certain land use and land cover changes (LUCC) in China. With better understanding of these trade-offs, this thesis contributes to optimum management for sustaining ecosystem services and supporting socio-economic development. The three case study areas are Hebei, Qinghai and Shandong provinces. I study trade-offs between landscape diversity and crop production, between grassland quality and livestock production, and between net primary productivity (NPP, a measure of the energy that enters ecosystems) and urbanization. After reviewing trade-off analyses of ecosystem services for sustainable land-use management (Chapter 2), the case studies are presented, with two chapters on Hebei, one on Qinghai, and three on Shandong. These chapters have econometric models for monitoring and assessing LUCC-induced ecosystem service changes, to enable quantitative analysis of the mechanisms available for policy-oriented optimum land-use management. The case study areas each have different policy interventions that are designed to preserve or restore natural capital. For example, Hebei has ecological restoration programs, such as the Green for Grain program, that are implemented in an attempt to conserve landscape diversity. Qinghai province has policies of enhancing ecological restoration for grassland conservation, in order to improve livestock production. Shandong province has enforced a prime cropland preservation policy in order to ensure high cropland productivity. Collectively, the case studies add to the literature on the use of sustainable land-use management strategies, while helping to illustrate some of the trade-offs that are central to environmental economics. The results highlight issues created by conversion of cultivated land to urban use, in both Hebei and Shandong. In Qinghai province, grassland degradation, livestock production and farmers’ income interact and affect LUCC and changes in ecosystem services. Restorative interventions, such as nature reserves, seem to have a positive effect on NPP, as a measure of ecosystem productivity. On the other hand, in Shandong province there is relatively low land productivity, as measured by the NPP, in regions covered by built-up area. While this thesis does not calculate a value for the produced capital and human capital in built-up areas, the reduction in the value of natural capital as a result of urbanization highlights the potential trade-offs and the need for careful measurement to help whether China is on a sustainable development path. In summary, the research in this thesis examines various land-use practices and management regimes for conserving ecosystem services, and contributes to the literature on how management of land use change and land cover change can influence ecosystem services in rapidly urbanizing China

Land Quality and Landscape Processes

This monograph contains a selection of scientific papers presented on the conference on Land Quality and Landscape Processes, hold in Keszthely, Hungary. It covers topics related to various aspects of land quality including : concepts of assessment; evaluation of biomass productivity ; bioindicators of land quality ; quality assessment of degraded land ; land use related data processingJRC.H.5-Land Resources Managemen

Regional estimation of daily to annual regional evapotranspiration with MODIS data in the Yellow River Delta wetland

Evapotranspiration (ET) from the wetland of the Yellow River Delta (YRD) is one of the important components in the water cycle, which represents the water consumption by the plants and evaporation from the water and the non-vegetated surfaces. Reliable estimates of the total evapotranspiration from the wetland is useful information both for understanding the hydrological process and for water management to protect this natural environment. Due to the heterogeneity of the vegetation types and canopy density and of soil water content over the wetland (specifically over the natural reserve areas), it is difficult to estimate the regional evapotranspiration extrapolating measurements or calculations usually done locally for a specific land cover type. Remote sensing can provide observations of land surface conditions with high spatial and temporal resolution and coverage. In this study, a model based on the Energy Balance method was used to calculate daily evapotranspiration (ET) using instantaneous observations of land surface reflectance and temperature from MODIS when the data were available on clouds-free days. A time series analysis algorithm was then applied to generate a time series of daily ET over a year period by filling the gaps in the observation series due to clouds. A detailed vegetation classification map was used to help identifying areas of various wetland vegetation types in the YRD wetland. Such information was also used to improve the parameterizations in the energy balance model to improve the accuracy of ET estimates. This study showed that spatial variation of ET was significant over the same vegetation class at a given time and over different vegetation types in different seasons in the YRD wetlan

Rodent Biology and Management; Abstracts of papers presented at the International Conference on Rodent Biology and Management, held at Beijing, China, 5-9 October 1998

Farm Management,

Comparative transcriptomic analysis reveals the coordinated mechanisms of Populus × canadensis ‘Neva’ leaves in response to cadmium stress

Cadmium (Cd), a heavy metal element has strong toxicity to living organisms. Excessive Cd accumulation directly affects the absorption of mineral elements, inhibits plant tissue development, and even induces mortality. Populus × canadensis ‘Neva’, the main afforestation variety planted widely in northern China, was a candidate variety for phytoremediation. However, the genes relieving Cd toxicity and increasing Cd tolerance of this species were still unclear. In this study, we employed transcriptome sequencing on two Cd?treated cuttings to identify the key genes involved in Cd stress responses of P. × canadensis ‘Neva’ l induced by 0 (CK), 10 (C10), and 20 (C20) mg/L Cd(NO3)2 4H2O. We discovered a total of 2,656 (1,488 up-regulated and 1,168 downregulated) and 2,816 DEGs (1,470 up-regulated and 1,346 down-regulated) differentially expressed genes (DEGs) between the CK vs C10 and CK vs C20, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses in response to the Cd stress indicated that many DEGs identified were involved in the catalytic activity, the oxidoreductase activity, the transferase activity, and the biosynthesis of secondary metabolites. Based on the enrichment results, potential candidate genes were identified related to the calcium ion signal transduction, transcription factors, the antioxidant defense system, and transporters and showed divergent expression patterns under the Cd stress. We also validated the reliability of transcriptome data with the real-time PCR. Our findings deeper the understanding of the molecular responsive mechanisms of P. × canadensis ‘Neva’ lon Cd tolerance and further provide critical resources for phytoremediation applications