scholarly journals Topographic Controls on Vegetation Changes in Alpine Tundra of the Changbai Mountains

Forests ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 756 ◽  
Author(s):  
Miaomiao Wu ◽  
Hong He ◽  
Shengwei Zong ◽  
Xinyuan Tan ◽  
Haibo Du ◽  
...  
Keyword(s):  
High Altitude ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Scale Effects ◽  
Alpine Tundra ◽  
Changbai Mountains ◽  
Vegetation Changes ◽  
Tundra Vegetation ◽  
Topographic Controls ◽  
Low Altitude

The vegetation of alpine tundra is undergoing significant changes and topography has played a significant role in mediating such changes. The roles of topography varied at different scales. In this study, we intended to identify topographic controls on tundra vegetation changes within the Changbai Mountains of Northeast China and reveal the scale effects. We delineated the vegetation changes of the last three decades using the normalized difference vegetation index (NDVI) time series. We conducted a trend analysis for each pixel to reveal the spatial change and used binary logistic regression models to analyze the relationship between topographic controls at different scales and vegetation changes. Results showed that about 30% of tundra vegetation experienced a significant (p < 0.05) change in the NDVI, with 21.3% attributable to the encroachment of low-altitude plants resulting in a decrease in the NDVI, and 8.7% attributable to the expansion of tundra endemic plants resulting in an increase in the NDVI. Plant encroachment occurred more severely in low altitude than in high altitude, whereas plant expansion mostly occurred near volcanic ash fields at high altitude. We found that plant encroachment tended to occur in complex terrains and the broad-scale mountain aspect had a greater effect on plant encroachment than the fine-scale local aspect. Our results suggest that it is important to include the mountain aspect in mountain vegetation change studies, as most such studies only use the local aspect.

scholarly journals Vegetation Dynamic Assessment by NDVI and Field Observations for Sustainability of China’s Wulagai River Basin

2021 ◽  
Vol 18 (5) ◽  
pp. 2528
Author(s):  
Panpan Chen ◽  
Huamin Liu ◽  
Zongming Wang ◽  
Dehua Mao ◽  
Cunzhu Liang ◽  
...  
Keyword(s):  
Species Diversity ◽  
River Basin ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Dynamic Assessment ◽  
Indicator System ◽  
Vegetation Changes ◽  
Vegetation Dynamic ◽  
Management Policies ◽  
The Impact

Accurate monitoring of grassland vegetation dynamics is essential for ecosystem restoration and the implementation of integrated management policies. A lack of information on vegetation changes in the Wulagai River Basin restricts regional development. Therefore, in this study, we integrated remote sensing, meteorological, and field plant community survey data in order to characterize vegetation and ecosystem changes from 1997 to 2018. The residual trend (RESTREND) method was utilized to detect vegetation changes caused by human factors, as well as to evaluate the impact of the management of pastures. Our results reveal that the normalized difference vegetation index (NDVI) of each examined ecosystem type showed an increasing trend, in which anthropogenic impact was the primary driving force of vegetation change. Our field survey confirmed that the meadow steppe ecosystem increased in species diversity and aboveground biomass; however, the typical steppe and riparian wet meadow ecosystems experienced species diversity and biomass degradation, therefore suggesting that an increase in NDVI may not directly reflect ecosystem improvement. Selecting an optimal indicator or indicator system is necessary in order to formulate reasonable grassland management policies for increasing the sustainability of grassland ecosystems.

scholarly journals Detecting Spatiotemporal Changes in Vegetation with the BFAST Model in the Qilian Mountain Region during 2000–2017

2019 ◽  
Vol 11 (2) ◽  
pp. 103 ◽  
Author(s):  
Liying Geng ◽  
Tao Che ◽  
Xufeng Wang ◽  
Haibo Wang
Keyword(s):  
Large Scale ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Anthropogenic Activities ◽  
Western China ◽  
Qinghai Lake ◽  
Vegetation Changes ◽  
Qilian Mountain ◽  
Modis Ndvi ◽  
Positive Effects

The Qilian Mountain ecosystems play an irreplaceable role in maintaining ecological security in western China. Vegetation, as an important part of the ecosystem, has undergone considerable changes in recent decades in this area, but few studies have focused on the process of vegetation change. A long normalized difference vegetation index (NDVI) time series dataset based on remote sensing is an effective tool to investigate large-scale vegetation change dynamics. The MODerate resolution Imaging Spectroradiometer (MODIS) NDVI dataset has provided very detailed regional to global information on the state of vegetation since 2000. The aim of this study was to explore the spatial-temporal characteristics of abrupt vegetation changes and detect their potential drivers in the Qilian Mountain area using MODIS NDVI data with 1 km resolution from 2000 to 2017. The Breaks for Additive Season and Trend (BFAST) algorithm was adopted to detect vegetation breakpoint change times and magnitudes from satellite observations. Our results indicated that approximately 80.1% of vegetation areas experienced at least one abrupt change from 2000 to 2017, and most of these areas were distributed in the southern and northern parts of the study area, especially the area surrounding Qinghai Lake. The abrupt browning changes were much more widespread than the abrupt greening changes for most years of the study period. Environmental factors and anthropogenic activities mainly drove the abrupt vegetation changes. Long-term overgrazing is likely the main cause of the abrupt browning changes. In addition, our results indicate that national ecological protection policies have achieved positive effects in the study area.

Analysis on Terrain Effects to Vegetation Coverage by Quantitative Remote Sensing

2012 ◽  
Vol 518-523 ◽  
pp. 5673-5677 ◽  
Author(s):  
Zheng Zheng Yu ◽  
Jun Ge Zhu ◽  
Yue Lei Qian
Keyword(s):  
Remote Sensing ◽  
High Altitude ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Vegetation Coverage ◽  
Mountain Area ◽  
Binary Model ◽  
Quantitative Remote Sensing ◽  
Terrain Effects ◽  
Low Altitude

In this paper,we use SPOT VEGETATION dataset of west mountain area of Henan provience in year 1998,2003 and 2008, calculated the vagetation coverage based on the normalized difference vegetation index and improved pixel binary model. And then, combine with the DEM, we quantitatively analysed the terrain effects to vegetation coverage,the result shows that: The vegetation coverage in high altitude areas was steady- going. But in the low altitude areas, the change of vegetation coverage is very sharp, and the ecosystem is fragile in the heavy gradient area. In the small slope areas, the probability of degradation and resoration both relative high; In a same phases,the vegetation coverage in south and north aspect is relatively high but lower in east and west aspect.The vegetation degradation in southwest aspect was more seriously than in southeast aspect.

scholarly journals Potential Distribution Shifts of Plant Species under Climate Change in Changbai Mountains, China

Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 498 ◽  
Author(s):  
Lei Wang ◽  
Wen J. Wang ◽  
Zhengfang Wu ◽  
Haibo Du ◽  
Shengwei Zong ◽  
...  
Keyword(s):  
Climate Change ◽  
Plant Species ◽  
Vegetation Change ◽  
Dwarf Shrub ◽  
Alpine Tundra ◽  
Changbai Mountains ◽  
Herbaceous Species ◽  
Data Set ◽  
Rcp 8.5 ◽  
Species Shifts

Shifts in alpine tundra plant species have important consequences for biodiversity and ecosystem services. However, recent research on upward species shifts have focused mainly on polar and high-latitude regions and it therefore remains unclear whether such vegetation change trends also are applicable to the alpine tundra at the southern edges of alpine tundra species distribution. This study evaluated an alpine tundra region within the Changbai Mountains, China, that is part of the southernmost alpine tundra in eastern Eurasia. We investigated plant species shifts in alpine tundra within the Changbai Mountains over the last three decades (1984–2015) by comparing contemporary survey results with historical ones and evaluated potential changes in the distribution of dwarf shrub and herbaceous species over the next three decades (2016–2045) using a combination of observations and simulations. The results of this study revealed that the encroachment of herbaceous plants had altered tundra vegetation to a significant extent over the last three decades, especially within low and middle alpine tundra regions in Changbai Mountains, China. The herbaceous species would continue shifting upward and expanding while their dwarf shrub counterparts would continue shifting upward and shrinking over the next three decades under the RCP 4.5 and RCP 8.5 scenarios. The upward shifts of plant species would not keep up with the rate of climate warming under the RCP 8.5 scenarios. The dominant plant tundra species may transform from dwarf shrubs to herbaceous varieties. The results of this study provide a scientific basis for biodiversity protection under climate change and a reference data set for additional research on alpine vegetation dynamics.

scholarly journals Soil Mesofauna Respond to the Upward Expansion of Deyeuxia purpurea in the Alpine Tundra of the Changbai Mountains, China

Plants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 615
Author(s):  
Yan Tao ◽  
Zhongqiang Wang ◽  
Chen Ma ◽  
Hongshi He ◽  
Jiawei Xu ◽  
...  
Keyword(s):  
Northeast China ◽  
Taxonomic Composition ◽  
Alpine Tundra ◽  
Changbai Mountains ◽  
Herbaceous Plant ◽  
Native Plant ◽  
Soil Mesofauna ◽  
Faunal Communities ◽  
Low Altitude ◽  
Different Levels

Deyeuxia purpurea, a low-altitude species, has been expanding upwards into alpine tundra, and this upward expansion is causing serious ecological consequences. However, few studies have been performed regarding its effects on soil faunal communities. We examine how the upward expansion of D. purpurea affects the abundance, richness, and diversity of soil mesofauna, and evaluate how different taxa of soil mesofauna respond to the upward expansion of D. purpurea in the alpine tundra of Changbai Mountains, northeast China. A total of 128 soil mesofaunal samples were collected from four treatments, namely high upward expansion (HU), medium upward expansion (MU), low upward expansion (LU), and native plant habitats (NP). The results revealed that the abundance of soil mesofauna was increased with the rise of D. purpurea upward expansion, and the taxonomic composition varied with the different levels of D. purpurea upward expansion in the alpine tundra of the Changbai Mountains. No unique taxa were collected in the native plant habitats, and the upward expansion of D. purpurea promoted the colonization of predatory invertebrates. Isotomidae and Gamasida responded positively to the herbaceous plant upward expansion, and thus they were considered to be a positive indicator of upward expansion. Hypogastruridae and Enchytraeidae responded relatively negatively, while Oribatida, Actinedida, and Pseudachorutidae had ambivalent responses to the upward expansion. Overall, the abundance of soil mesofauna can indicate the levels of the upward expansion of D. purpurea. Soil mesofaunal guild characteristics were altered by the upward expansion. The different taxa of soil mesofauna responded to herbaceous plants’ upward expansion to various degrees. Therefore, this study provide evidence supporting the fact that the abundance of soil mesofauna can indicate the levels of upward expansion of D. purpurea, but the responses of soil mesofauna to the upward expansion of D. purpurea differ among their taxa.

scholarly journals Biophysical Determinants of Shifting Tundra Vegetation Productivity in the Beaufort Delta Region of Canada

Ecosystems ◽  
2022 ◽  
Author(s):  
Jordan H. Seider ◽  
Trevor C. Lantz ◽  
Txomin Hermosilla ◽  
Michael A. Wulder ◽  
Jonathan A. Wang
Keyword(s):  
Random Forests ◽  
Climate Warming ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Future Research ◽  
Delta Region ◽  
Vegetation Productivity ◽  
Tundra Vegetation ◽  
Glaciofluvial Deposits ◽  
The Impact

AbstractTemperature increases across the circumpolar north have driven rapid increases in vegetation productivity, often described as ‘greening’. These changes have been widespread, but spatial variation in their pattern and magnitude suggests that biophysical factors also influence the response of tundra vegetation to climate warming. In this study, we used field sampling of soils and vegetation and random forests modeling to identify the determinants of trends in Landsat-derived Enhanced Vegetation Index, a surrogate for productivity, in the Beaufort Delta region of Canada between 1984 and 2016. This region has experienced notable change, with over 71% of the Tuktoyaktuk Coastlands and over 66% of the Yukon North Slope exhibiting statistically significant greening. Using both classification and regression random forests analyses, we show that increases in productivity have been more widespread and rapid at low-to-moderate elevations and in areas dominated by till blanket and glaciofluvial deposits, suggesting that nutrient and moisture availability mediate the impact of climate warming on tundra vegetation. Rapid greening in shrub-dominated vegetation types and observed increases in the cover of low and tall shrub cover (4.8% and 6.0%) also indicate that regional changes have been driven by shifts in the abundance of these functional groups. Our findings demonstrate the utility of random forests models for identifying regional drivers of tundra vegetation change. To obtain additional fine-grained insights on drivers of increased tundra productivity, we recommend future research combine spatially comprehensive time series satellite data (as used herein) with samples of high spatial resolution imagery and integrated field investigations.

scholarly journals Digital Examination of Vegetation Changes in River Floodplain Wetlands Based on Remote Sensing Images: A Case Study Based on the Downstream Section of Hailar River

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1206
Author(s):  
Xi Dong ◽  
Zhibo Chen
Keyword(s):  
Remote Sensing ◽  
Water Supply ◽  
Plant Community ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Forest Vegetation ◽  
High Rate ◽  
Vegetation Changes ◽  
Herbaceous Plant ◽  
Sparse Vegetation

The Hailar River is an important river in the Inner Mongolia Autonomous Region, China. It plays an extremely important role in maintaining the ecological balance of the region. However, in recent decades, the Hailar River and its surrounding areas have been developed at a high rate and its wetland resources have faced various threats. In this study, vegetation changes in the Hailar River wetlands were analyzed using remote sensing data from the Landsat TM (1987, 2001, and 2010) and Landsat OLI-TIRS (2019) satellites. A vegetation change model was developed using Matlab software to assess vegetation changes in the area. There were significant changes in the wetland vegetation of the lower Hailar River study site between 1987 and 2019. There was an increase in open sand habitat with a sparse vegetation area of 1.08 km2, a decrease in grassland area of 13.17 km2, and an increase in the forest area of 15.91 km2. The spatial distribution of the normalized difference vegetation index (NDVI) varied across the study site and was high overall. The vegetation types varied with distance from the river. There are two possible explanations for positive and negative vegetation change trends. In areas where the water supply is sufficient and relatively stable, the cover of forest vegetation was gradually increasing and the herbaceous plant community is gradually evolving into a scrub woodland plant community. In areas where the water supply is lacking, there are changes in the sense of a decrease of forest vegetation and an increase of open sand habitat with sparse vegetation. Therefore, this study suggests that the existing wetlands should be protected, used wisely, and developed rationally to provide sustainable resources for the next generation.

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