Quantitative contributions of climate change and human activities to vegetation changes over multiple time scales on the Loess Plateau

2021 ◽  
Vol 755 ◽  
pp. 142419 ◽  
Author(s):  
Shangyu Shi ◽  
Jingjie Yu ◽  
Fei Wang ◽  
Ping Wang ◽  
Yichi Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Loess Plateau ◽  
Human Activities ◽  
Multiple Time Scales ◽  
Vegetation Changes ◽  
Multiple Time ◽  
The Loess Plateau ◽  
Quantitative Contributions

scholarly journals Are We Doing ‘Systems’ Research? An Assessment of Methods for Climate Change Adaptation to Hydrohazards in a Complex World

2019 ◽  
Vol 11 (4) ◽  
pp. 1163 ◽  
Author(s):  
Melissa Bedinger ◽  
Lindsay Beevers ◽  
Lila Collet ◽  
Annie Visser
Keyword(s):  
Climate Change ◽  
Human Nature ◽  
Climate Change Adaptation ◽  
Time Scales ◽  
Spatial Scales ◽  
Local Context ◽  
Multiple Time Scales ◽  
Future Research ◽  
Multiple Time ◽  
Systems Research

Climate change is a product of the Anthropocene, and the human–nature system in which we live. Effective climate change adaptation requires that we acknowledge this complexity. Theoretical literature on sustainability transitions has highlighted this and called for deeper acknowledgment of systems complexity in our research practices. Are we heeding these calls for ‘systems’ research? We used hydrohazards (floods and droughts) as an example research area to explore this question. We first distilled existing challenges for complex human–nature systems into six central concepts: Uncertainty, multiple spatial scales, multiple time scales, multimethod approaches, human–nature dimensions, and interactions. We then performed a systematic assessment of 737 articles to examine patterns in what methods are used and how these cover the complexity concepts. In general, results showed that many papers do not reference any of the complexity concepts, and no existing approach addresses all six. We used the detailed results to guide advancement from theoretical calls for action to specific next steps. Future research priorities include the development of methods for consideration of multiple hazards; for the study of interactions, particularly in linking the short- to medium-term time scales; to reduce data-intensivity; and to better integrate bottom–up and top–down approaches in a way that connects local context with higher-level decision-making. Overall this paper serves to build a shared conceptualisation of human–nature system complexity, map current practice, and navigate a complexity-smart trajectory for future research.

scholarly journals Detecting the Dominant Cause of Streamflow Decline in the Loess Plateau of China Based onthe Latest Budyko Equation

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1277 ◽  
Author(s):  
Jing Zhao ◽  
Shengzhi Huang ◽  
Qiang Huang ◽  
Hao Wang ◽  
Guoyong Leng
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Human Activities ◽  
Soil Conservation ◽  
Potential Evaporation ◽  
The Loess Plateau ◽  
Study Region ◽  
Water And Soil Conservation ◽  
The Wei River Basin ◽  
Streamflow Change

Quantifying the relative contributions of climate variability and human activity to streamflow change is important for effective water resource use and management. Four sub-catchments of the Wei River Basin (WRB) in the Loess Plateau in China were selected as the study region, where the evolution of parameter α from the latest Budyko equation (Wang-Tang equation) was explored using an 11-year moving window. The elasticity of streamflow was derived from the climatic aridity index, represented by the ratio of annual potential evaporation ( E P ) to annual precipitation ( P ), and catchment characteristics as represented by α . The effects of climate change and human activities on streamflow change during 1971–2010 were quantified with climate elasticity and decomposition methods. The contributions of different types of human activities to streamflow were further empirically determined using the water and soil conservation method. Results indicate that (1) under the same climate condition ( P and E P ), a higher value of α caused an increase in evaporation rate ( E / P ) and a decrease in runoff. Changes in these hydrological variables led to a subsequent reduction in streamflow in the WRB; (2) The absolute value of the precipitation elasticity was larger than the potential evaporation elasticity, indicating that streamflow change was more sensitive to precipitation; (3) The results based on the two methods were consistent. Climate change and human activities contributed to the decrease in streamflow by 29% and 71%, respectively, suggesting that human activities have exerted more profound impacts on streamflow in the study region; (4) Contributions of different water and soil conservation measures to streamflow reduction were calculated and sorted in descending order: Irrigation, industrial and domestic consumption, terrace, afforestation, reservoirs, check-dams, then grass-planting.

scholarly journals Spatial and Temporal Analyses of Vegetation Changes at Multiple Time Scales in the Qilian Mountains

2021 ◽  
Vol 13 (24) ◽  
pp. 5046
Author(s):  
Lifeng Zhang ◽  
Haowen Yan ◽  
Lisha Qiu ◽  
Shengpeng Cao ◽  
Yi He ◽  
...  
Keyword(s):  
Time Scales ◽  
Qilian Mountains ◽  
Dominant Factor ◽  
Multiple Time Scales ◽  
Vegetation Changes ◽  
Multiple Time ◽  
Temperature And Precipitation ◽  
The Qilian Mountains ◽  
Vegetation Variation

The Qilian Mountains (QLMs), an important ecological protective barrier and major water resource connotation area in the Hexi Corridor region, have an important impact on ecological security in western China due to their ecological changes. However, most existing studies have investigated vegetation changes and their main driving forces in the QLMs on the basis of a single scale. Thus, the interactions among multiple environmental factors in the QLMs are still unclear. This study was based on normalised difference vegetation index (NDVI) data from 2000 to 2019. We systematically analysed the spatial and temporal characteristics of the QLMs at multiple time scales using trend analysis, ensemble empirical mode decomposition, Geodetector, and correlation analysis methods. At different time scales under single-factor and multi-factor interactions, we examined the mechanisms of the vegetation changes and their drivers. Our results showed that the vegetation in the QLMs showed a trend of overall improvement in 2000–2019, at a rate of 0.88 × 10−3, mainly in the central western regions. The NDVI in the QLMs showed a short change cycle of 3 and 5 years and a long-term trend. Sunshine time and wind speed were the main drivers of the vegetation variation in the QLMs, followed by temperature. Precipitation affected the vegetation spatial variation within a certain altitude range. However, temperature and precipitation had stronger explanatory powers for the vegetation variation in the western QLMs than in the eastern part. Their interaction was the dominant factor in the regional differences in vegetation. The responses of the NDVI to temperature and precipitation were stronger in the long time series. The main drivers of vegetation variation were land surface temperature and precipitation in the east and temperature and evapotranspiration in the west. Precipitation was the main driver of vegetation growth in the northern and southwestern QLMs on both the short- and long-term scales. Vegetation changes were more significantly influenced by short-term temperature changes in the east but by a combination of temperature and precipitation in most parts of the QLMs on a 5-year time scale.

scholarly journals Climate change effects on drought severity

2008 ◽  
Vol 17 ◽  
pp. 23-29 ◽  
Author(s):  
A. Loukas ◽  
L. Vasiliades ◽  
J. Tzabiras
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Standardized Precipitation Index ◽  
Precipitation Index ◽  
Geographical Information ◽  
Multiple Time Scales ◽  
Drought Severity ◽  
Multiple Time ◽  
Monthly Precipitation ◽  
Climate Change Effects

Abstract. This paper evaluates climate change effects on drought severity in the region of Thessaly, Greece. The Standardized Precipitation Index (SPI) has been used for estimation of drought severity. A geographical information system is applied for the division of Thessaly region to twelve hydrological homogeneous areas based on their geomorphology. Mean monthly precipitation values from 50 precipitation stations of Thessaly for the hydrological period October 1960–September 1990 were used for the estimation of mean areal precipitation. These precipitation timeseries have been used for the estimation of Standardized Precipitation Index (SPI) for multiple time scales (1-, 3-, 6-, 9-, and 12-months) for each sub-basin or area. The outputs of Global Circulation Model CGCM2 were applied for two socioeconomic scenarios, namely, SRES A2 and SRES B2 for the assessment of climate change impact on droughts. The GCM outputs were downscaled to the region of Thessaly using a statistical methodology to estimate precipitation time series for two future periods 2020–2050 and 2070–2100. A method has been proposed for the estimation of annual cumulative drought severity-time scale-frequency curves. These curves integrate the drought severity and frequency for various types of drought. The SPI timeseries and annual weighted cumulative drought severity were estimated and compared with the respective timeseries and values of the historical period 1960–1990. The results showed that the annual drought severity is increased for all hydrological areas and SPI time scales, with the socioeconomic scenario SRES A2 being the most extreme.

scholarly journals Comparative Assessment of Vegetation Dynamics under the Influence of Climate Change and Human Activities in Five Ecologically Vulnerable Regions of China from 2000 to 2015

Forests ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 317 ◽  
Author(s):  
Hao Wang ◽  
Guohua Liu ◽  
Zongshan Li ◽  
Pengtao Wang ◽  
Zhuangzhuang Wang
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Ecological Restoration ◽  
Loess Plateau ◽  
Human Activities ◽  
Vegetation Dynamics ◽  
Karst Region ◽  
The Tibetan Plateau ◽  
The Loess Plateau ◽  
Arid Desert

Ongoing climate change and human activities have a great effect on vegetation dynamics. Understanding the impact of climate change and human activities on vegetation dynamics in different ecologically vulnerable regions has great significance in ecosystem management. In this study, the predicted NPP (Net Primary Productivity) and the actual NPP based on different ecological process data and models were combined to estimate the vegetation dynamics and their driving forces in the Northern Wind-sand, Loess Plateau, Arid Desert, Tibetan Plateau, and Karst regions from 2000 to 2015. The results indicated that the NPP in all ecologically vulnerable regions showed a restoration trend, except for that in the Karst region, and the percentage of areas in which NPP increased were, in order, 78% for the Loess Plateau, 71% for the Northern Wind-sand, 69% for the Arid Desert, 54% for the Tibetan Plateau, and 31% for the Karst regions. Vegetation restorations in the Northern Wind-sand and Arid Desert regions were primarily attributable to human activities (86% and 61% of the restoration area, respectively), indicating the success of ecological restoration programs. The Loess Plateau had the largest proportion of vegetation restoration area (44%), which was driven by combined effects of climate and human factors. In the Tibetan Plateau, the vegetation changes due to climate factors were primarily distributed in the west, while those due to human factors were primarily distributed in the east. Human activities caused nearly 60% of the vegetation degradation in the Karst region. Based on these results, it is recognizable that regional climate conditions are the key factor that limits ecological restoration. Therefore, future policy-making should pay more attention to the local characteristics of different ecological vulnerable regions in regional ecosystem management to select reasonable restoration measures, improve restoration efficiency, and maximize the benefits of ecological restoration programs.

SOME REMARKS ON THE MULTIPLE TIME SCALES OF DIFFUSION IN MINERALS AND MELTS

2018 ◽  
Author(s):  
Yan Liang ◽  
◽  
Daniele J. Cherniak ◽  
Chenguang Sun
Keyword(s):  
Time Scales ◽  
Multiple Time Scales ◽  
Multiple Time
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