Emergent Vegetation Coverage and Human Activities Influence Oviposition Microhabitat Selection by Invasive Bullfrogs (Lithobates catesbeianus) in Southwestern China

2016 ◽  
Vol 50 (1) ◽  
pp. 57 ◽  
Author(s):  
Xuan Liu ◽  
Yisong Guo ◽  
Yu Luo ◽  
Yiming Li
Keyword(s):  
Human Activities ◽  
Emergent Vegetation ◽  
Southwestern China ◽  
Vegetation Coverage ◽  
Microhabitat Selection ◽  
Lithobates Catesbeianus

scholarly journals Effect of Check Dam on Sediment Load Under Vegetation Restoration in the Hekou-Longmen Region of the Yellow River

2022 ◽  
Vol 9 ◽  
Author(s):  
Zeyu Zhang ◽  
Junrui Chai ◽  
Zhanbin Li ◽  
Li Chen ◽  
Kunxia Yu ◽  
...  
Keyword(s):  
Human Activities ◽  
Sediment Load ◽  
Yellow River ◽  
Reduction Rate ◽  
Vegetation Restoration ◽  
Vegetation Coverage ◽  
Dam Construction ◽  
Check Dam ◽  
Reduction Effect ◽  
Sediment Reduction

With years of vegetation restoration and check dam construction on the Loess Plateau, the sediment load of the middle reaches of the Yellow River have decreased sharply; however, the effects of check dam on this decrease of sediment load with such extensive vegetation restoration remains unclear. In order to further clarify the effects of check dam on sediment load reduction under vegetation restoration, we calculated vegetation coverage and check dam index based on multi-source remote sensing data, and calculated sediment reduction rate caused by human activities by Mann-Kendall statistical test and double cumulative curve, then established regression equations incorporating the check dam index and the sediment reduction rate using data from different geomorphic regions with different vegetation coverages. The results showed that sediment load in the Hekou-Longmen region and its 17 tributaries decreased significantly every year, and the change in sediment load could be divided into 3 typical periods: the base period (P1), the period mainly impacted by check dam construction (P2) and the period with comprehensive impact of check dam construction and vegetation restoration (P3). Compared with sediment load of the tributaries during P1, the sediment load decreased by 60.96% during P2 and by 91.76% during P3. Compared with the contribution of human activities to the reduction in sediment load in P2, the contribution of human activities in P3 increased significantly, while that of precipitation decreased slightly. The sediment reduction effect of check dams is greater in basins with low vegetation coverage than in basins with high vegetation coverage. There are differences in sediment reduction effect of vegetation restorations in different geomorphic regions, and the effect of vegetation restoration alone have certain upper limits. Such as, the upper limit of sediment reduction rate of vegetation restoration for rivers flowing through the sandstorm region is 47.86%. Hence, only combined the construction of check dam with vegetation restoration can it achieve more significant sediment reduction benefit and control soil erosion more effectively.

scholarly journals Spatiotemporal Variation of Vegetation Coverage and Its Response to Climate Factors and Human Activities in Arid and Semi-Arid Areas: Case Study of the Otindag Sandy Land in China

2020 ◽  
Vol 12 (12) ◽  
pp. 5214 ◽  
Author(s):  
Hao Wang ◽  
Fei Yao ◽  
Huasheng Zhu ◽  
Yuanyuan Zhao
Keyword(s):  
Human Factors ◽  
Human Activities ◽  
Vegetation Dynamics ◽  
Spatiotemporal Variation ◽  
Vegetation Coverage ◽  
Arid Areas ◽  
Climate Factors ◽  
Sandy Land ◽  
Otindag Sandy Land ◽  
Semi Arid

Vegetation coverage is a key variable in terrestrial ecosystem monitoring and climate change research and is closely related to soil erosion and land desertification. In this article, we aimed to resolve two key scientific issues: (1) quantifying the spatial-temporal vegetation dynamics in the Otindag Sandy Land (OSL); and (2) identifying the relative importance of climate factors and human activities in impacting vegetation dynamics. Based on correlation analysis, simple regression analysis, and the partial derivative formula method, we examined the spatiotemporal variation of vegetation coverage in the OSL, belonging to the arid and semiarid region of northern China, and their interaction with climate-human factors. The results showed that the vegetation coverage of the area showed a downward trend with a rate of −0.0006/a during 2001–2017, and gradually decreased from east to west. Precipitation was the main climate factor controlling the overall distribution pattern of vegetation coverage, while the human factors had a more severe impact on the vegetation coverage than the climate factors in such a short period, and the overall impact was negative. Among the human factors, population pressure, urbanization, industrialization, pastoral production activities, and residents’ lifestyles had a negative impact. However, ecological restoration polices alleviated the contradiction between human development and vegetation deterioration. The results of this article provide a scientific basis for restoring grassland systems in arid and semi-arid areas

scholarly journals Copula-Based Abrupt Variations Detection in the Relationship of Seasonal Vegetation-Climate in the Jing River Basin, China

2019 ◽  
Vol 11 (13) ◽  
pp. 1628 ◽  
Author(s):  
Jing Zhao ◽  
Shengzhi Huang ◽  
Qiang Huang ◽  
Hao Wang ◽  
Guoyong Leng ◽  
...  
Keyword(s):  
River Basin ◽  
Human Activities ◽  
Urban Areas ◽  
Large Scale ◽  
Vegetation Index ◽  
Climatic Factors ◽  
Potential Evapotranspiration ◽  
Change Points ◽  
Vegetation Coverage ◽  
The Relationship

Understanding the changing relationships between vegetation coverage and precipitation/temperature (P/T) and then exploring their potential drivers are highly necessary for ecosystem management under the backdrop of a changing environment. The Jing River Basin (JRB), a typical eco-environmentally vulnerable region of the Loess Plateau, was chosen to identify abrupt variations of the relationships between seasonal Normalized Difference Vegetation Index (NDVI) and P/T through a copula-based method. By considering the climatic/large-scale atmospheric circulation patterns and human activities, the potential causes of the non-stationarity of the relationship between NDVI and P/T were revealed. Results indicated that (1) the copula-based framework introduced in this study is more reasonable and reliable than the traditional double-mass curves method in detecting change points of vegetation and climate relationships; (2) generally, no significant change points were identified during 1982–2010 at the 95% confidence level, implying the overall stationary relationship still exists, while the relationships between spring NDVI and P/T, autumn NDVI and P have slightly changed; (3) teleconnection factors (including Arctic Oscillation (AO), Pacific Decadal Oscillation (PDO), Niño 3.4, and sunspots) have a more significant influence on the relationship between seasonal NDVI and P/T than local climatic factors (including potential evapotranspiration and soil moisture); (4) negative human activities (expansion of farmland and urban areas) and positive human activities (“Grain For Green” program) were also potential factors affecting the relationship between NDVI and P/T. This study provides a new and reliable insight into detecting the non-stationarity of the relationship between NDVI and P/T, which will be beneficial for further revealing the connection between the atmosphere and ecosystems.

scholarly journals Assessment of soil erosion in the Dongting Lake Basin, China: Patterns, drivers, and implications

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261842
Author(s):  
Jianyong Xiao ◽  
Binggeng Xie ◽  
Kaichun Zhou ◽  
Shana Shi ◽  
Junhan Li ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Soil Erosion ◽  
Human Activities ◽  
Dongting Lake ◽  
Vegetation Coverage ◽  
Lake Basin ◽  
Driving Mechanism ◽  
Land Use Types ◽  
Key Factor

Soil loss caused by erosion is a global problem. Therefore, the assessment of soil erosion and the its driving mechanism are of great significance to soil conservation. However, soil erosion is affected by both climate change and human activities, which have not been quantified, and few researchers studied the differences in the driving mechanisms of soil erosion depending on the land use type. Therefore, the spatiotemporal characteristics and changing trends of soil erosion in the Dongting Lake Basin were analyzed in this study. Geographic detectors were used to identify the dominant factors affecting soil erosion in different land use types. In this study, a sensitivity experiment was conducted to clarify the relative contributions of climate change and human activities to soil erosion changes. In addition, we studied the effects of different land use types and vegetation cover restoration on soil erosion. The results show that soil erosion in the Dongting Lake Basin decreased from 2000 to 2018. Human activities represented by land use types and vegetation coverage significantly contributed to the alleviation of soil erosion in the Dongting Lake Basin, whereas climate change represented by rainfall slightly aggravated soil erosion in the study area. The restoration of grassland vegetation and transfer of cultivated land to woodlands in the study area improved the soil erosion. The slope steepness is the key factor affecting the intensity of soil erosion in dry land, paddy fields, and unused land, whereas the vegetation coverage is the key factor affecting the intensity of soil erosion in woodland, garden land, and grassland. Detailed spatiotemporally mapping of soil erosion was used to determine the connections between soil erosion and potential drivers, which have important implications for vegetation restoration and the optimization of land use planning.

scholarly journals Quantifying the Influences of Natural Factors and Human Activities on NDVI Changes in the Hanjiang River Basin, China

2020 ◽  
Vol 12 (22) ◽  
pp. 3780
Author(s):  
Ting Chen ◽  
Jun Xia ◽  
Lei Zou ◽  
Si Hong
Keyword(s):  
River Basin ◽  
Human Activities ◽  
Urban Areas ◽  
Vegetation Index ◽  
Vegetation Coverage ◽  
Vegetation Growth ◽  
Natural Factors ◽  
Range Type ◽  
Hanjiang River ◽  
The Impact

The Hanjiang River Basin (HJRB) is an important source area for drinking water in Hubei Province, China, and the vegetation coverage there is important to the ecological system. Due to the spatial heterogeneity and synergistic effect of various factors, it is very difficult to identify the main factors affecting vegetation growth in the HJRB. With the normalized difference vegetation index (NDVI) data from 2001 to 2018 in the HJRB, the spatiotemporal patterns of NDVI and the influences of natural factors and human activities on NDVI were investigated and quantified based on the Mann-Kendall (M-K) test, partial correlation analysis, and Geographical Detector. The individual factors and their interactions and the range/type of factor attributes suitable for vegetation growth were also examined. NDVI in the HJRB increased from 2001 to 2018, and the variation rate was 0.0046 year−1. NDVI was increasing in 81.17% of the area (p < 0.05). Elevation and slope can effectively explain the vegetation distribution. The interactions of factors on NDVI were significant, and the interactions of the elevation and precipitation can maximize the impact among all factors. The range of available landforms is thought to be highly conducive to vegetation growth. The rates of the annual precipitation and annual mean temperature changed from 2001 to 2018, which were 3.665 mm/year and 0.017 °C/year, and the regions where NDVI positively correlated with them were over 85%. Contrary to the general trend, NDVI has obviously decreased in urban areas since 2010. The quantitative findings of this study can help us better understand the effects of various factors on vegetation growth and provide appropriate suggestions for vegetation protection and restoration in the HJRB.

scholarly journals Does Climate Change or Human Activity Lead to the Degradation in the Grassland Ecosystem in a Mountain-Basin System in an Arid Region of China?

2019 ◽  
Vol 11 (9) ◽  
pp. 2618 ◽  
Author(s):  
Junjie Yan ◽  
Guangpeng Zhang ◽  
Xiaoya Deng ◽  
Hongbo Ling ◽  
Hailiang Xu ◽  
...  
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Arid Region ◽  
Vegetation Coverage ◽  
Soil Drought ◽  
Grassland Ecosystem ◽  
Grassland Vegetation ◽  
Irrigated Area ◽  
The Impact ◽  
Basin System

In mountain-basin systems in the arid region, grasslands are sensitive to the impacts of climate change and human activities. In this study, we aimed to resolve two key scientific issues: (1) distinguish and explain the laws of grassland ecosystem deterioration in a mountain-basin system and identify the key factors related; and (2) evaluate whether damaged grasslands ecosystem have the potential for natural revegetation. Hence, by combining spatial analysis with statistical methods, we studied the trends of the deterioration of the grassland ecosystem and its spatial characteristics in Kulusitai, a mountain-basin system in the arid region of Northwest China. According to our results, vegetation coverage and productivity exhibited significant decreasing trends, while the temperature vegetation drought index (TVDI) exhibited a significant increasing trend. Drainage of groundwater, because of increase in irrigation for the expanded irrigated area around Kulusitai, and climate warming were the critical triggers that leaded to the soil drought. Soil drought and overgrazing, resulting from the impact of human activities, were the main factors responsible for the deterioration of the grassland ecosystems. However, limiting the number of livestock to a reasonable scale and reducing the irrigated area may help to increase the soil moisture, thus promoting the germination of soil seed banks and facilitating the normal growth of grassland vegetation. Furthermore, based on analysis of the phenology of the grassland vegetation, the reasonable period for harvesting and storage is from July 29 to August 5. The results of this study provide a scientific basis and practical guide for restoring mountain-basin grassland systems in arid regions.

Climate and human induced 2000-year vegetation diversity change in Yunnan, southwestern China

The Holocene ◽  
2021 ◽  
pp. 095968362110417
Author(s):  
Yongbo Wang ◽  
Ying Xie ◽  
Xingqi Liu ◽  
Ji Shen ◽  
Yong Wang ◽  
...  
Keyword(s):  
Human Activities ◽  
Vegetation History ◽  
Southwestern China ◽  
Fossil Pollen ◽  
Pollen Assemblage ◽  
Vegetation Diversity ◽  
Climate Fluctuations ◽  
Isotope Record ◽  
Hill Numbers ◽  
Dominant Condition

Understanding long-term vegetation diversity patterns and their potential responses to climate and/or human driven processes are important for ecosystem modeling and conservation. Late-Holocene fossil pollen assemblage and associated vegetation diversity estimates provide an opportunity to explore the interactions among vegetation, climate, and human activities. A continuous 2000-year palynological record was obtained from the Beihai Wetland, southwestern China, to represent regional vegetation history, particularly the vegetation diversity changes. The results indicate that regional vegetation was dominated by deciduous broadleaved forest components (e.g. Alnus, deciduous Quercus), which showed a gradual decrease accompanied by expansion of herbaceous taxa (mainly Poaceae) after AD 800. Such progressive decline of forest was attributed to regional deforestation driven by intensified human activities, which was further confirmed by the increasing non-pollen polymorph abundance, particularly an abrupt rise after AD 1350. Vegetation diversity based on the Hill numbers ( N0, N1, and N2) showed a dramatic decline between ca. AD 200–400, which was triggered by regional fire events as shown by increased charcoal abundance from a nearby lake. The vegetation diversity reduced gradually after AD 800, especially the vegetation richness reflected by N0, revealing the transitional process from climate-driven to human-dominated vegetation changes. Minor increases of vegetation diversity occurred during Chinese dynastical transitions, probably due to reduced human activities following war-induced population crises. On the multidecadal scale, variations in vegetation diversity correlated significantly with climate fluctuations (revealed by synthesized temperature of China and stable oxygen isotope record from Dongge Cave) before AD 800, indicating a climate dominant condition. Then, the correlation between vegetation diversity and climate declined after AD 800, representing a progressive transition to human-dominant condition. In addition, the compositional turnover based on DCCA of the fossil pollen assemblage revealed a stepwise decrease, indicating reduced vegetation turnovers under anthropogenic influences.

scholarly journals Vegetation Determines Lake Sediment Carbon Accumulation during Holocene in the Forest–Steppe Ecotone in Northern China

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 696
Author(s):  
Qian Hao ◽  
Shilei Yang ◽  
Zhaoliang Song ◽  
Zhengang Wang ◽  
Changxun Yu ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Human Activities ◽  
Accumulation Rate ◽  
Carbon Accumulation ◽  
Vegetation Coverage ◽  
Soil Conditions ◽  
Forest Steppe ◽  
Organic Carbon Content ◽  
The Past ◽  
Local Soil

To understand the past carbon accumulation of forest–steppe ecotone and to identify the main drivers of the long-term carbon dynamics, we selected Huangqihai Lake and analyzed the sediment records. We measured the organic carbon content (TOC; %) of sedimentary samples and quantified the carbon accumulation rate (CAR; g C m−2 yr−1). Furthermore, the climate, soil erosion, and vegetation development of the past 6800 years were reconstructed using physicochemical parameters and pollen records. Human activities were also obtained from a 2200-year history record. Our results showed that the CAR was high during 5800~4100 cal yr BP (40~60 g C m-2 yr-1), which is mainly attributed to the high sediment accumulation rate (SAR) during this period. Pearson’s correlation, redundancy analysis and hierarchical variation partitioning analyses suggested that the CAR was influenced by the SAR and TOC, while vegetation dynamics (broadleaved tree percentage and vegetation coverage) and local soil erosion were the main drivers of the TOC and SAR. Especially when the vegetation was dominated by broadleaved forests, the CAR was significantly high due to the high gross primary productivity and carbon density of forest compared with steppe. Our study highlights the direct influence of local vegetation and soil erosion on the CAR, whereas climate might influence indirectly by changing local vegetation and soil conditions. Moreover, our results showed that human activities had positive influences on the carbon accumulation dynamics in this region since 2200 cal yr BP by influencing the SAR.

scholarly journals Formation-Evolutionary Mechanism Analysis and Impacts of Human Activities on the 20 August 2019 Clustered Debris Flows Event in Wenchuan County, Southwestern China

2021 ◽  
Vol 9 ◽  
Author(s):  
Yu Li ◽  
Xing-nian Liu ◽  
Bin-rui Gan ◽  
Xie-kang Wang ◽  
Xing-guo Yang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Human Activities ◽  
Debris Flows ◽  
Large Scale ◽  
Field Investigation ◽  
Mitigation Measures ◽  
Southwestern China ◽  
Economic Losses ◽  
Mechanism Analysis ◽  
Prediction And Prevention

Characterized by large scale, high frequency, and strong destructiveness, debris flow has become the most noticeable geohazards throughout the world, especially in the mountainous areas of southwestern China. On August 20, 2019, large-scale heavy rainfall pummeled Wenchuan County, Sichuan Province, Southwestern China, which resulted in a cluster of debris flows (the “8·20” clustered debris flows event), and caused considerable economic losses (approximately 3.4 billion RMB were lost) and heavy casualties (48,862 people were displaced, 16 people died and 22 people went missing). Based on field investigation, image data interpretation, mechanism analysis, and other methods, this study reveals the formation mechanism, dynamic evolutionary process, and impacts of human activities on the “8·20” clustered debris flows event. Results from a comprehensive analysis indicate that the occurrence of short-term, high-intensity rainfall and the excessive supply of solid material were the main factors that triggered this catastrophic event. With the debris flow flowing into the main river, this event presented an extremely apparent disaster chain effect. It is also found that improper site selection and inadequate design of human activities played a crucial role in the movement process of the debris flow that directly aggravated the losses. Finally, to improve debris flow prediction and prevention, some early warning and mitigation measures are discussed.

Sign in / Sign up

Export Citation Format

Share Document