Climate Change, Growing Season Water Deficit And Vegetation Activity Along The North-South Transect Of Eastern China From 1982 Through 2006

Considerable work has been done to examine the relationship between environmental constraints and vegetation activities represented by the remote sensing-based normalized difference vegetation index (NDVI). However, the relationships along either environmental or vegetational gradients are rarely examined. The aim of this paper was to identify the vegetation types that are potentially susceptible to climate change through examining their interactions between vegetation activity and evaporative water deficit. We selected 12 major vegetation types along the north–south transect of eastern China (NSTEC), and tested their time trends in climate change, vegetation activity and water deficit during the period 1982–2006. The result showed significant warming trends accompanied by general precipitation decline in the majority of vegetation types. Despite that the whole transect increased atmospheric evaporative demand (ET<sub>0</sub>) during the study period, the actual evapotranspiration (ET<sub>a</sub>) showed divergent trends with ET<sub>0</sub> in most vegetation types. Warming and water deficit exert counteracting controls on vegetation activity. Our study found insignificant greening trends in cold temperate coniferous forest (CTCF), temperate deciduous shrub (TDS), and three temperate herbaceous types including the meadow steppe (TMS), grass steppe (TGS) and grassland (TG), where warming exerted more effect on NDVI than offset by water deficit. The increasing growing season water deficit posed a limitation on the vegetation activity of temperate coniferous forest (TCF), mixed forest (TMF) and deciduous broad-leaved forest (TDBF). Differently, the growing season brownings in subtropical or tropical forests of coniferous (STCF), deciduous broad-leaved (SDBF), evergreen broad-leaved (SEBF) and subtropical grasslands (STG) were likely attributed to evaporative energy limitation. The growing season water deficit index (GWDI) has been formulated to assess ecohydrological equilibrium and thus indicating vegetation susceptibility to water deficit. The increasing GWDI trends in CTCF, TCF, TDS, TG, TGS and TMS indicated their rising susceptibility to future climate change

Climate change, growing season water deficit and vegetation activity along the north–south transect of eastern China from 1982 through 2006

Considerable work has been done to examine the relationship between environmental constraints and vegetation activities represented by the remote sensing-based normalized difference vegetation index (NDVI). However, the relationships along either environmental or vegetational gradients are rarely examined. The aim of this paper was to identify the vegetation types that are potentially susceptible to climate change through examining their interactions between vegetation activity and evaporative water deficit. We selected 12 major vegetation types along the north–south transect of eastern China (NSTEC), and tested their time trends in climate change, vegetation activity and water deficit during the period 1982–2006. The result showed significant warming trends accompanied by general precipitation decline in the majority of vegetation types. Despite that the whole transect increased atmospheric evaporative demand (ET0) during the study period, the actual evapotranspiration (ETa) showed divergent trends with ET0 in most vegetation types. Warming and water deficit exert counteracting controls on vegetation activity. Our study found insignificant greening trends in cold temperate coniferous forest (CTCF), temperate deciduous shrub (TDS), and three temperate herbaceous types including the meadow steppe (TMS), grass steppe (TGS) and grassland (TG), where warming exerted more effect on NDVI than offset by water deficit. The increasing growing season water deficit posed a limitation on the vegetation activity of temperate coniferous forest (TCF), mixed forest (TMF) and deciduous broad-leaved forest (TDBF). Differently, the growing season brownings in subtropical or tropical forests of coniferous (STCF), deciduous broad-leaved (SDBF), evergreen broad-leaved (SEBF) and subtropical grasslands (STG) were likely attributed to evaporative energy limitation. The growing season water deficit index (GWDI) has been formulated to assess ecohydrological equilibrium and thus indicating vegetation susceptibility to water deficit. The increasing GWDI trends in CTCF, TCF, TDS, TG, TGS and TMS indicated their rising susceptibility to future climate change

Drought characterization: A systematic literature review

This study examined the worsening severity of global droughts caused by climate change. However, the multiple definitions and varied range of drought indices pose challenges in effectively monitoring and assessing the prevalence and severity of droughts. This study aims to give a comprehensive overview of the various drought definitions found in the literature and how they have evolved based on their applications. Specifically, the focus was to shed light on the dynamic nature of drought characterization and offer insights into the factors that shaped its conceptualization over time. Within this context, this study explored three primary categories of drought indices: climatic, remote sensing, and composite. Each category was discussed in relation to its utility in specific fields, such as meteorological, agricultural, and hydrological drought assessments, along with an analysis of their strengths and limitations. Furthermore, this study presents modified meteorological drought indices that have been adapted to better monitor agricultural droughts. Additionally, the authors used geographic information systems to create a map showing the distribution of drought-related publications globally over the past decade. The findings showed that countries with arid and semi-arid climates are more actively involved in drought research, highlighting their particular interest and concern regarding the subject matter. The implications of this study emphasize the urgent need for immediate and coordinated efforts to address the escalating issue of droughts caused by climate change. By improving monitoring and assessment methods and focusing on tailored strategies in vulnerable regions, it is possible to mitigate the far-reaching consequences of drought and to build more resilient communities and ecosystems

Analyse spatiale pour l'hydrogéologie en milieu boréal québécois : bilan hydrologique et gestion du territoire

Quantifier la ressource en eau stockée dans les aquifères peu profonds et déterminer leurs interactions avec l’eau de surface est essentiel pour mieux évaluer la sensibilité de l’eau souterraine et des écosystèmes qui en dépendent découlant du changement climatique et des impacts de l’activité humaine. Cependant, l'évaluation de la ressource en eau est complexe sur des territoires vastes éloignés où les données préexistantes sont rares et limitées. Cette étude se concentre sur l'utilisation d'approches SIG à grande échelle pour produire de nouvelles informations sur les ressources en eaux souterraines peu profondes. La zone d'étude couvre 185 000 km2 englobant de vastes bassins versants boréaux du bassin de la Baie-James (Canada). Une analyse spatiale multicritères (AMC) basée sur des données géologiques et hydrogéologiques a été couplée à des calculs géométriques afin d'évaluer le volume des aquifères granulaires peu profonds et d'identifier les zones où la protection des eaux souterraines doit être prioritaire. Des données satellitaires et des modèles spatiaux combinés à des données in situ, telles que des mesures de débit et la composition géochimique de l’eau (isotopes stables [δ2H-δ18O] et conductivité électrique), ont ensuite été utilisés pour calculer le bilan hydrologique terrestre et estimer les composantes du cycle de l'eau. Enfin, un nouvel indice calculé à partir de 290 images thermiques du satellite Landsat 8, a été créé pour révéler l'emplacement de potentiels occurrences d’écosystèmes dépendant des eaux souterraines (POEDES). Les résultats ont suggéré que les aquifères potentiels (AP) les plus importants sont principalement associés à des formations fluvioglaciaires. Ils contiennent en moyenne 8,5 m de sédiments saturés pour une évaluation globale d’environ 40 km3 ± 10%. La contribution annuelle des eaux souterraines au débit des rivières est généralement inférieure à 12% des précipitations. La contribution de l’eau provenant des pluies et de la fonte des neiges est de 30 à 61% et de 18 à 40%, respectivement, avec des ratios évaporation sur les apports de 2 à 10%. Le débit présente des cycles saisonniers avec une contribution plus élevée d’eau de fonte des neiges pendant la crue printanière et de l'eau de pluie à l'automne, une composition évoluant vers celle des eaux souterraines pendant la période de glace et une contribution relativement stable de l’eau souterraine tout au long de l'année. Les terres proches des cours d'eau dans les vallées principales présentent les plus haut POEDES. Une analyse en composantes principales des caractéristiques des bassins versants révèle des corrélations significatives entre les paramètres des eaux souterraines estimés au cours de cette étude. Une topologie de bassins versants est proposée à partir des deux premières composantes qui expliquent 77% de la variance. Les bassins versants au sud du territoire dépendent plus des écoulements souterrains que ceux situés au nord qui montrent une surface plus imperméable. Quatre regroupements de bassins versants identifient les secteurs où une vigilance accrue des eaux souterraines est nécessaire pour préserver la ressource en eau et la biodiversité qui dépend des eaux souterraines

Climate Change and Environmental Sustainability-Volume 4

Anthropogenic activities are significant drivers of climate change and environmental degradation. Such activities are particularly influential in the context of the land system that is an important medium connecting earth surface, atmospheric dynamics, ecological systems, and human activities. Assessment of land use land cover changes and associated environmental, economic, and social consequences is essential to provide references for enhancing climate resilience and improving environmental sustainability. On the one hand, this book touches on various environmental topics, including soil erosion, crop yield, bioclimatic variation, carbon emission, natural vegetation dynamics, ecosystem and biodiversity degradation, and habitat quality caused by both climate change and earth surface modifications. On the other hand, it explores a series of socioeconomic facts, such as education equity, population migration, economic growth, sustainable development, and urban structure transformation, along with urbanization. The results of this book are of significance in terms of revealing the impact of land use land cover changes and generating policy recommendations for land management. More broadly, this book is important for understanding the interrelationships among life on land, good health and wellbeing, quality education, climate actions, economic growth, sustainable cities and communities, and responsible consumption and production according to the United Nations Sustainable Development Goals. We expect the book to benefit decision makers, practitioners, and researchers in different fields, such as climate governance, crop science and agricultural engineering, forest ecosystem, land management, urban planning and design, urban governance, and institutional operation.Prof. Bao-Jie He acknowledges the Project NO. 2021CDJQY-004 supported by the Fundamental Research Funds for the Central Universities and the Project NO. 2022ZA01 supported by the State Key Laboratory of Subtropical Building Science, South China University of Technology, China. We appreciate the assistance of Mr. Lifeng Xiong, Mr. Wei Wang, Ms. Xueke Chen, and Ms. Anxian Chen at School of Architecture and Urban Planning, Chongqing University, China