Changes In Vegetation Cover Research Articles

Long-Term Variability of Vegetation Cover and Its Driving Factors and Effects over the Zuli River Basin in Northwest China

Vegetation information is a critical factor in regional environment management under climate change. In this study, a typical arid and semi-arid watershed on the Loess Plateau, the Zu Li River Basin (ZRB), was selected to study the long-term changes in vegetation cover and its drivers and impacts. Unlike existing normalized vegetation index (NDVI) products, which have coarse spatial resolution and short time horizons, this study used the 30 m Landsat dataset analyzed in the Google Earth Engine (GEE) to generate high-resolution and long-term NDVI data, which are the most ideal for monitoring vegetation dynamics using long-time-series data products. The results showed that the annual mean maximum NDVI (normalized vegetation index) in the ZRB increased during 1987–2021, with a significant (p < 0.05) increasing trend in most areas. Upstream vegetation cover increased more than midstream and downstream, but the increase was smaller. Precipitation in the ZRB area was significantly (p < 0.05) correlated with the NDVI series, except for the upstream pass area, where human activities played an important role. NDVI was significantly (p < 0.05) negatively correlated with runoff coefficient and sand content, indicating that vegetation cover was an important reason for the decrease in runoff coefficient and sand content.

Estimating fractional vegetation cover and aboveground biomass for land degradation assessment in eastern Mongolia steppe: combining ground vegetation data and remote sensing

ABSTRACT Fractional vegetation cover (FVC) and aboveground biomass (AGB) are critically important for monitoring grassland degradation, and their accurate estimation can be used as key proxies for assessing land degradation. The main purpose of this study was to estimate the FVC and AGB in the eastern Mongolian steppe using remote sensing and machine learning. In this context, spectral bands and vegetation indices were extracted from the processed Sentinel-2 data and used as predictors. The field vegetation data were derived from the Mongolian pasture-monitoring database, which consisted of 256 plots with FVC and AGB measurements. Consequently, we derived FVC and AGB from Sentinel-2 imagery using 256 field vegetation measurements in the vast eastern Mongolian steppe as a reference for random forest (RF) models (R2 FVC = 0.81, R²AGB = 0.76). Among the variables, the predictor variables derived from spectral vegetation and soil indices, especially NDVI, Simple Ratio (SR), and OSAVI, were highly important for predicting FVC and AGB. As expected, a comparison among the map values showed that the spatial distribution of FVC and AGB was consistent with the landscapes and ecoregions in the study area. As the FVC and AGB maps only showed the current condition of vegetation cover, we also analysed NDVI trends to explain vegetation cover changes. We tested temporal trends in vegetation using Landsat NDVI time series data and the Mann-Kendall trend test. This revealed that in 7.3% of the area, the NDVI significantly increased, whereas a significant decrease was observed in 58% of the area.

Hydrological and botanical diversity of a raised bog and its evaluation using in situ and remote sensing methods

Peatland vegetation requires water-logged conditions for peat-forming plant communities to survive. Changes in water regimes have been found to alter the soil environment and cause shifts in species composition. Occasionally, the spatial and chronological constraints in water table monitoring impede the correct evaluation of the status of these sensitive ecohydrological systems. Therefore, it is important to combine in situ and remote sensing methods to assess ecohydrological diversity over large areas of threatened peatland ecosystems. The present study assessed the relationship between hydrological indicators (the in situ water table fluctuations of 57 measurement wells and five study plots in the 2019 and 2020 growing seasons); botanical indicators (in situ species composition in three raised bog habitat types, namely, bog woodland, a semi-open raised bog, and an open raised bog); and spectral indices (NDVI – Normalised Difference Vegetation Index and NDWI – Normalised Difference Water Index, 2015–2020, Sentinel 2) for the evaluation of heterogeneous raised bog spatial patterns and temporal change. There were statistically significant relationships between vegetation and water table depth in different raised bog habitat types. Deeper water tables prevailed in woodland habitats (trees, green mosses, Rhododendron tomentosum) and vice versa in areas where open raised bog plants (Sphagnum) occupied the surface. Moderate relationships (r > |0.4|, p <.05) were detected between some of the botanical and hydrological indicators and spectral indices. The application of high-resolution remote sensing data may be useful for raised bog measurements, and changes in vegetation cover and related spectral indices may become hydroclimatic indicators.

Long-Term Tibetan Alpine Vegetation Responses to Elevation-Dependent Changes in Temperature and Precipitation in an Altered Regional Climate: A Case Study for the Three Rivers Headwaters Region, China

Recent studies offer more evidence that the rate of warming is amplified with elevation, indicating thereby that high-elevation ecosystems tend to be exposed to more accelerated changes in temperature than ecosystems at lower elevations. The phenomenon of elevation-dependent warming (EDW), as one of the regional climate-change impacts, has been observed across the Tibetan Plateau. Studies have often found large-scale greening trends, but the drivers of vegetation dynamics are still not fully understood in this region, such that the local implications of vegetation change have been infrequently discussed. This study was designed to quantify and characterize the seasonal changes in vegetation across the Three Rivers Headwaters Region (TRHR), where the land cradles the headwaters of the Yangtze, the Yellow, and the Lancang (Mekong). By mapping the normalized difference vegetation index (NDVI) over the growing season from 1982 to 2015, we were able to evaluate seasonal changes in vegetation cover over time. The results show a slightly increased tendency in green vegetation cover, which could possibly be attributed to sustained warming in this region over the past three decades, whereas a decline in the green-up rate with elevation was found, indicating an inconsistent trend of vegetation greening with EDW. The cause of the green-up rate decline at high elevations could be linked to the reduced soil water availability induced by the fast increase in warming rates associated with EDW. The findings of this study have important implications for devising adaptation strategies for alpine ecosystems in a changing climate.

The vegetation cover dynamics and potential drivers of habitat change over 30 years in the Free State National Botanical Garden, South Africa

As a conservation strategy, the South African National Biodiversity Institute (SANBI) establishes biodiversity gardens in areas with unique vegetation types that are vulnerable to extinction. The study aimed to (1) determine the vegetation cover dynamics of the Free State National Botanical Garden (FSNBG) over a 30-year period (1987–2017), focusing on different vegetation classes; (2) evaluate the ecological integrity of the Critical Biodiversity Area 1 (CBA1) vegetation using species abundance and vegetation cover; and (3) quantify potential conservation threats that may be drivers of vegetation cover changes. The “moderate vegetation cover” and “dense vegetation cover” had increased by 25.1 ha and 8.6 ha respectively in the FSNBG. Woody vegetation cover expanded significantly over the past 30-year period, suggesting “bush” encroachment. Shannon–Wiener diversity indices showed high overall plant species diversity of CBA1 vegetation type (H = 3.5), with the vegetation cover remaining high (79.6 ± 15.9%), 50 plant species no longer existing, suggesting reduced taxonomic richness. Major conservation threats included the presence of 27 alien and invasive plant species interspersed within different vegetation patches and anthropogenic habitat fragmentation in the past 19 years (i.e. covering ~ 18% of the buffer zone). We conclude that increased vegetation cover is associated with bush encroachment and we recommend interventions to reduce the population density of woody plants and establish permanent vegetation monitoring plots.

Unveiling the impact of traditional land practices on natural vegetation using large-scale exclosures: National borders and military bases

Attributing the extent of changes in vegetation cover which are the result of human actions or of climate variability is challenging. The Negev Desert, bordered by two countries and the Palestinian Authority and crossing three climate zones, provides a natural laboratory for unveiling the impact of land practices on natural vegetation. Desert vegetation on both sides of the border was traditionally subject to herds grazing and bush gathering, but in recent decades; grazing policy, military training areas, and nature protection have excluded traditional uses. We used remotely sensed derived proxies of vegetation (the Normalized Difference Vegetation Index) and surface albedo from satellite images inside and outside of the large exclosures to estimate the anthropogenic impact on vegetation cover in the past four decades, and ultimately isolate the effect of traditional land uses on vegetation cover. Our results showed that the cross-border differences in land use led to a significant impact on vegetation cover outside the exclosed areas. These cross-border differences were more pronounced in the semi-arid - arid climate regions and decreased in the hyper-arid climate region. Exclosures provide a natural experiment which enables us the testing of the factors driving changes in natural vegetation.

A 20-year vegetation cover change and its response to climate factors in the Guangdong-Hong Kong-Macao Greater Bay Area under the background of climate change

IntroductionThe Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is located in the south subtropical area along the southeast coast of China, which is one of the world-class urban agglomerations and an important part for economic development. In order to investigate the change of vegetation indexes and its response to climate factors in such circumstance of climate change, this study is an important component in the protection and establishment of the ecological environment in the GBA.MethodsThe Moderate Resolution Imaging Spectroradiometer-Enhanced Vegetation Index (MODIS-EVI) and climate data were recorded from National Aeronautics and Space Administration (NASA) and Resource and Environment Science Data Center of the Chinese Academy of Sciences. Trend analysis, Mann-Kendall (MK) Test and rescaled range analysis (R/S Analysis) offer an effective way of analyzing the correlation between the vegetation cover change and climate factors.ResultsThe results provide important insights into the following aspects: (1) The changes of climate factors (temperature, precipitation, wind speed, humidity, and sunshine radiation) are fluctuated in GBA, with no obvious increasing or decreasing trend. It comprehensively exhibited an extremely slow development of humidify and warming. (2) It presents an increasing trend of EVI in GBA, with the rate of 0.0045/a. The range of increase is in the middle level (0.4 ≤ EVI&amp;lt;0.6) based on the EVI. The vegetation cover in GBA is improved comprehensively, the area of vegetation improvement is larger than the area of vegetation degression, with the extremely improved vegetation cover area (66.98%) and the extremely degraded vegetation cover area (5.70%). There are obvious differences and agglomerations in the distribution of the EVI trends. (3) In future, the changing trends will be combinedly affected be various factors, and there is no obvious factor temporarily. The improved vegetation cover area (over 80%) are predicted. (4) There are significant spatiotemporal differences in the annual effects of EVI on various climate factors comprehensively. Wind speed and relative humidity have the strongest correlations with EVI; the area of significant correlation is more than 40% of the pixels. The correlation between temperature and EVI is second, with the area of significant correlation over 20% of the pixels. The precipitation and sunshine radiation weakly correlated with EVI, with the area of significant correlation is less than 5% of the pixels.DiscussionThe result of this study indicated that the EVI changing trend in the future by R/S analysis method is affected by climate and human factors together and there are no significant factors. The result indicated precipitation has no significant correlation with EVI trends in the Hot and humid area with mean precipitation of 1800mm. However, there is a significant positive correlation between the EVI trend and two climate factors (relative humidity and wind speed). In the terms of spatial distribution, the influence of temperature to EVI is complex in GBA, the spatial distribution of correlation is scattered.

Attribution analysis of runoff evolution in Kuye River Basin based on the time-varying budyko framework

The underlying surface parameters in the Budyko framework (such as parameter n in the Choudhury–Yang equation) are crucial for studying the relationship between precipitation, evapotranspiration, and runoff. It is important to accurately quantify the influence of climate and human activities on the evolution of underlying surface characteristic parameters. However, due to the spatiotemporal heterogeneity of underlying surface parameters, it is often difficult to accurately quantify these relationships. In this study, taking the Kuye River Basin located in the northern Loess Plateau as the research object, we first used trend analysis and non-linear regression methods to estimate the evolution characteristics of runoff and underlying surface parameter n. We then determined the contribution of runoff changes by using the elasticity coefficient method under the 9-year moving average window. The results showed that: 1) the Kuye River Basin runoff underwent a sudden change in 1997, and the complex human activities are the main reasons for the sharp runoff decrease. 2) In addition to precipitation and potential evapotranspiration, temperature changes will alter the basin’s underlying surface parameters, ultimately changing the runoff. Moreover, climate change first inhibited and then promoted the runoff reduction trend. 3) Human activities, represented by changes in vegetation coverage and coal mining, considerably influenced runoff evolution in Kuye River Basin. More importantly, the change of runoff in the Kuye River Basin caused by coal mining is approximately four times that of the normalized vegetation index. This study can improve the applicability of the Budyko framework in the Loess Plateau sub-basin and provide scientific guidance for water resource management.

Temporal Variations of Sediment Provenance in a Karst Watershed, China

The environmental quality of the sediments in karst areas is a common concern, and it is of great significance to analyze the sources of the sediments. This study investigates the sources and its temporal variations of catchment sediments in a typical small karst watershed area. Toxic metal concentrations in the catchment area were monitored via three geochemical baseline projects in China. The sediment identification fingerprint tool (SIFT) was used to establish a geochemical model for tracing the main source contributions and its temporal variations of catchment sediments over the past 28 years (1992–2019). The catchment sediments in the small karst catchment area were mainly sourced from the background lithologies, among which limestone contributed the most, followed by dolomite, sand-shale, and mudstone; however, the anthropogenic lead–zinc tailings contributed the least. The contributions and temporal variations of each source were closely related to the lithology, topography, and landform, as well as the change in land-use and vegetation cover and the degree of rocky desertification. Moreover, the implementation of vegetation restoration and control of rocky desertification decreased the contributions of the upstream geological bodies, and the toxic metal content of the catchment sediment decreased accordingly. This study is of great significance for environmental governance in karst areas.

Pollution and Climatic Influence on Trees in the Siberian Arctic Wetlands

Siberian Arctic wetlands located within the planetary “warming hotspot” experience pronounced climate-driven vegetation cover changes. Together with warming, wetlands, which are located within the influence of Norilsk copper and nickel industry (69.35° N, 88.12° E), have been strongly influenced by industrial pollutions (sulfur dioxide mostly) since the 1940s. In addition, petroleum products release occurred in 2020 that potentially influenced vegetation vigor. We studied the combined effect of climate warming and pollution on the larch (Larix sibirica Ledeb.) and shrubs’ (Salix spp. and alder, Duschekia fruticosa) growth. Using satellite data (MODIS and Sentinel) processing, we mapped wetlands within the study area. We used on-ground survey, and applied dendrochronology, climate variables, and emissions rate analysis. We sampled woods (kerns) and, based on the tree ring analysis, generated trees and shrubs growth index (GI) chronologies. We analyzed the influence of the SO2 emissions and eco-climate variables (air temperatures, precipitation, soil moisture, and drought index SPEI) on the larch and shrubs GI. We mapped GPP and NPP (gross and net primary productivity) and vegetation index NDVI and temporal trends of these indexes based on the MODIS-derived products. We found that chronic SO2 influence led to larch trees GI decrease that was followed by tree mortality, which was observed until the end of 1990. Since the beginning of the 2000s, the GI of larch and shrubs has increased, which is correlated with elevated air and soil temperature and growth season prolongation, whereas excessive soil moisture negatively influenced GI. Together with that, increasing trends of vegetation indexes (GPP, NPP, and NDVI) were observed on the part of wetland within the zone of former trees’ heavy damage and mortality. The trends began mostly in 2003–2005 and were caused by emissions volume decrease and warming, together with resistant species’ (willows, graminoids, bushes, and birch) growth and invasion. We suggested that increasing productivity trends might partly be attributed to nitrogen fertilization caused by NOx emissions. Finally, we found that diesel fuel spill which happened in 2020 caused no influence on the larch, whereas some aquatic species (mosses mostly) were damaged.

Research on the Establishment of Carbon Inversion Model in Engebei Ecological Demonstration Area of the Kubuqi Desert Based on Remote Sensing Data

Studying the changes of vegetation coverage and carbon storage in terrestrial ecosystem will provide important information for ecosystem optimization. The Kubuqi Desert is a typical ecological fragile area, and its ecological construction is not only to build an ecological barrier to protect northern China, but also to be a case of similar regions in the world. Engebei ecological demonstration area, located in the northern margin of the central Kubuqi Desert, was selected as the study area. The objective is to establish a carbon inversion model through the LASSO regression model in this area which can promote its ecological development. Taking Landsat, Sentinel-2A remote sensing data and field sample data as data sources. The vegetation coverage was calculated through the remote sensing data. The carbon reserves in plots were calculated through the biomass equation. Then, the appropriate carbon storage estimation model was found out, which was established by the LASSO regression model and the Sentinel-2A remote sensing images. Finally, the carbon reserves over the years were calculated by this estimation model. Research shows that: first, the overall vegetation coverage of the study area was not high, which was around 27% – 37%; second, the proportion of lower (Ⅰ) level vegetation coverage in the study area decreased overall, and the proportion of higher (Ⅴ) level vegetation coverage generally stabilized; third, carbon reserves remain roughly above 71752.64t, up by 20,209.61t in 2021 compared to 2020, and up by 14,867.02t in 2021 compared to 1991.

祁连山国家公园植被时空变化及其对人类活动的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 祁连山国家公园植被时空变化及其对人类活动的响应 DOI: 10.5846/stxb202107221990 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 甘肃省创新群体项目（20JR10RA038）；中国科学院"西部之光"交叉团队项目-重点实验室合作研究专项；国家重点研发计划项目（2019YFC0507401） Spatial and temporal changes in vegetation cover and response to human activities in Qilian Mountain National Park Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:祁连山国家公园地处青藏、蒙新、黄土三大高原交汇地带的祁连山北麓，作为国家公园体制试点之一，是我国重要的生态功能区、水源涵养地和生物多样性保护优先区域，其生态功能不可忽视。以祁连山国家公园2000-2019年归一化植被指数（NDVI）和净初级生产力（NPP）数据为基础，结合气温、降水、土地利用、矿产开采和旅游发展数据，利用泰尔-森趋势分析（Theil-Sen趋势分析）、曼-肯德尔检验（Mann-Kendall显著性检验）、土地转移概率矩阵和多元残差分析方法，分析该区域的植被时空分布特征、变化趋势特征及其对气候变化和人类活动的响应。结果表明：（1）2000-2019年祁连山国家公园内NDVI和NPP在空间上呈现出东南高西北低，由东南向西北递减的格局。时间上呈现上升趋势，上升速率分别为0.0053/a和0.0014/a；（2）祁连山国家公园内NPP提高、降低和稳定区域分别占总面积的87.29%、0.40%和12.30%。降低区域零星分布于整个国家公园，其中在走廊南山和冷龙岭交汇处，靠近甘青两省交界边缘分布最为集中。提高区域分布广泛，尤其以国家公园东部最为明显；（3）祁连山国家公园NDVI与气温呈现显著正相关区域约占40.18%，与降水呈现正相关区域约占25.70%，气温上升、降水增多促进了国家公园植被生长，适宜的水热组合对植被生长更有利；（4）人类活动对植被变化的影响具有两面性：约有28.91%矿业、旅游和水电站在整改、规范之后植被生长状况仍较差，生态环境没有明显恢复；退耕还林还草工程、生态林建设工程成效显著，近3年林地、草地面积增多。（5）祁连山国家公园大部分植被覆盖变化是由气候变化和人类活动共同导致。 Abstract:Qilian Mountain National Park is located in the north piedmont of Qilian Mountains at the intersection of Qinghai-Tibet, Mongolian-Xinjiang and Loess. As one of the national park system pilots, Qilian Mountain National park is an important ecological function area, a water retention area and a priority area for biodiversity conservation in China, and its ecological functions cannot be ignored. Based on the Normalized Difference Vegetation Index (NDVI) and Net Primary Productivity (NPP) of Qilian Mountain National Park from 2000-2019, combined with temperature, precipitation, land use, mineral extraction and tourism development data, we used the Theil-Sen slope estimation, Mann-Kendall test, land transfer matrix and multivariate residual analysis methods to analyze the spatial and temporal distribution characteristics of vegetation, change trend characteristics and its response to climate change and human activities. The results showed that (1) NDVI and NPP in Qilian Mountain National Park from 2000 to 2019 showed a spatial pattern of high in the southeast and low in the northwest, decreasing from southeast to northwest. Temporally, they showed an increasing trend, with an increase rate of 0.0053/a and 0.0014/a, respectively. (2) The improved, decreased and stable areas of NPP in Qilian Mountain National Park accounted for 87.29%, 0.40% and 12.30% of the total area, respectively. Decreased areas are scattered throughout the national park, with the most concentrated distribution at the intersection of Zoulang South Mountains and Lenglongling, near the border edge of Gansu and Qinghai provinces. The improved areas are widely distributed, especially the most obvious in the eastern part of the national park. (3) The NDVI of Qilian Mountain National Park shows a significant positive correlation with temperature in about 40.18% of the area, and a positive correlation with precipitation in about 25.70% of the area, the increase in temperature and precipitation promotes the growth of vegetation in the national park, and a suitable combination of hydrothermal conditions is more favorable to the growth of vegetation.(4) The impact of human activities on vegetation changes was two-sided:Approximately 28.91% of mining, tourism and hydroelectric power stations in the national park still had poor vegetation growth after rectification and regulation, and the ecological environment has not recovered significantly; The cropland to forest and grassland conversion projects and ecological forest projects have been effective, the area of forest and grassland has increased, in the past three years.(5) Most of the vegetation cover changes in Qilian Mountain National Park were caused by a combination of climate change and human activity. 参考文献 相似文献 引证文献

2001-2019年黄土高原植被覆盖度时空演化特征及地理因子解析

PDF HTML阅读 XML下载 导出引用 引用提醒 2001-2019年黄土高原植被覆盖度时空演化特征及地理因子解析 DOI: 10.5846/stxb202106241686 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国博士后科学基金特别资助项目(2020T130074);国家自然科学基金重大项目(41790445);中国博士后科学基金面上资助项目(2017M622982) Spatio-temporal variations of vegetation coverage and its geographical factors analysis on the Loess Plateau from 2001 to 2019 Author: Affiliation: Fund Project: China Postdoctoral Science Foundation 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:探究黄土高原植被覆盖度变化及其与地理因子之间的关系有助于区域植被恢复政策的优化以及人地关系的协调发展。因此,以MOD13 A1数据作为数据基础,采用趋势分析、标准差和重心迁移模型,研究2001-2019年黄土高原植被覆盖度FVC(Fractional Vegetation Cover)时空演化特征,并结合地理探测器和相关分析对影响FVC的地理因子进行解析。结果表明:(1)2001-2019年黄土高原植被覆盖度恢复状况较好,FVC平均增速为0.0095/a,呈东南高西北低分布,极显著、显著增加的区域面积占比为84.37%,研究区各年FVC重心位于陕北一带,19年向北推进55.1km;(2)各地理因子对FVC的解释力存在显著差异,降水、土壤类型、气温、土地利用类型和坡度是FVC空间分布的主要驱动因子,且各因子之间交互作用的解释力高于单因子;(3)FVC与气温、降水相关系数均以正相关为主;FVC均值与变化趋势存在地形、土壤、人口密度、土地利用分异特征;土地利用转移可体现人类活动特征,其退耕还林还草、未利用地绿化等积极效应促使区域植被得到显著改善,城市扩张等消极效应则抑制植被增长。 Abstract:Exploring the relationship between vegetation coverage change and geographical factors on the Loess Plateau is conducive to the optimization of regional vegetation restoration policies and the coordinated development of man-land relations. Therefore, based on MOD13A1 data, using trend analysis, standard deviation and gravity migration model, the temporal and spatial evolution characteristics of FVC (Fractional Vegetation Cover) in Loess Plateau from 2001 to 2019 were studied, and the geographical factors affecting FVC were analyzed with GeoDetector and correlation analysis. The results show that: (1) the vegetation coverage recovery of the Loess Plateau was good from 2001 to 2019, and the average growth rate of FVC was 0.0095/a, with a high distribution rate in southeast and low distribution rate in northwest, and the area proportion of extremely significant and significantly increased was 84.37%. The center of gravity of FVC in the study area each year was located in northern Shaanxi, and it advanced 55.1km northward in 19 years. (2) There were significant differences in the explanatory power of each geographical factor on FVC. Precipitation, soil type, air temperature, land use type and slope were the main driving factors of FVC spatial distribution, and the explanatory power of interaction among the factors was higher than that of the single factor. (3) The correlation coefficient of FVC with temperature and precipitation was mainly positive, and the mean value and trend of FVC were characterized by terrain, soil, population density and land use differentiation. Land use transfer can reflect the characteristics of human activities, and its positive effects, such as returning farmland to forest and grassland, greening unused land and so on, can significantly improve regional vegetation, while the negative effects, such as urban expansion, can inhibit vegetation growth. 参考文献 相似文献 引证文献

Approach for Monitoring Spatiotemporal Changes in Fractional Vegetation Cover Through Unmanned Aerial System-Guided-Satellite Survey: A Case Study in Mining Area

Approach for Monitoring Spatiotemporal Changes in Fractional Vegetation Cover Through Unmanned Aerial System-Guided-Satellite Survey: A Case Study in Mining Area

The impact of climate change and wildfire on decadal alpine vegetation dynamics

Context Climate-induced changes of alpine vegetation diversity, cover and composition have been recorded globally, but most insights have been gleaned from field studies over small spatiotemporal scales. Aims We assess dynamics in climate and vegetation of Australia’s highest and most biologically diverse alpine area that surrounds Mount Kosciuszko (~455 km2), as well as recovery following the 2003 wildfires. Methods Climatic changes were analysed using gridded climate data for mean annual temperature (1910–2019) and seasonal precipitation (1900–2019), and changes in snow cover were assessed from snow course records (1954–2021). A vegetation cover time series (1990, 2000, 2010, 2020) was modelled with an optimised random forest classification using recursive feature selection, and the LandTrendr algorithm was used to detect areas burnt during wildfires. Key results Over time, temperatures and summer precipitation increased, whereas snow cover and winter precipitation decreased. Subsequently, vegetation dynamics were dominated by the densification of subalpine woodlands at lower elevations, replacing dry and wet heathlands. There was treeline stasis but upslope advancement of dry and wet shrublines but grassland vegetation types were relatively stable. However, in burnt areas there was suppressed upslope advancement of shrublines, treeline recession and relatively less expansion of subalpine woodlands. Conclusions Alpine vegetation may be impacted by climate change incrementally through relatively gradual changes in climatic conditions, and transformatively through landscape-level disturbance from wildfires. Implications Higher temperatures and altered precipitation regimes increase the frequency and severity of wildfires, which may be amplified by increasing fuel loads and dryness from the proliferation and advance of woody vegetation in alpine areas.

Multiple ecological effects and their drivers of ecological restoration programmes in the Qinghai‐Tibet Plateau, China

AbstractA series of ecological restoration programmes (ERPs) have been implemented in the Qinghai‐Tibet Plateau to reverse ecological deterioration. However, the multiple ecological benefits of these ERPs and their driving factors remain unclear. This study analyzed the dynamic changes in fractional vegetation cover (FVC), ecosystem services [water yield (WY), net primary productivity (NPP), and soil conservation (SC)], and sustainable development goals (SDGs) in the Forest Protection and Construction Programme (FPCP), Grassland Protection and Construction Programme (GPCP), Sandy Land Control Programme (SLCP), and Soil Erosion Control Programme (SECP) in the Qinghai‐Tibet Plateau from 2000 to 2015. The geographically weighted regression model was used to reveal the spatial differences of drivers of various ecological benefits. The results showed that ecological benefits increased synergistically in the GPCP and SLCP, while trade‐offs between NPP and WY were observed for the FPCP and SECP. ERPs resulted in a significant increase (p &lt; 0.05) in FVC, SDG 15.1.1, and SDG 15.3.1 and a significant decrease (p &lt; 0.01) in SDG 15.4.2, except for the SLCP. ERPs improved the FVC, WY, and SC, but did not reverse grassland degradation. The ecological benefits of the FPCP and SLCP were poor after 2010, while the ecological benefits of the SLCP have been better since 2012. FVC and WY were dominated by precipitation, and NPP was dominated by FVC. Slope dominated SC in the GPCP, SECP, and SLCP, while precipitation dominated SC in the FPCP. This study can provide scientific support for sustainable vegetation management.

Evaluating the impacts of Payment for Ecosystem Services (water supplies) in an agricultural system of the Brazilian Cerrado.

In this study, we investigated the effects of the Payment for Ecosystem Services (PES) in an agrisystem located in the Brazilian Midwest. This PES benefits the owners of rural properties that encompass springs that feed the Abóbora River microbasin which supplies water for consumption in the city of Rio Verde, Goiás. We evaluated the percentage of native vegetation cover around the springs of the watercourses and also estimated its change over time (2005, 2011 and 2017). The vegetation cover of the Areas of Permanent Preservation (APP) increased by 2.24% on average, seven years after the implantation of the PES. There was little difference in the change of vegetation cover maintained over the study years (2005, 2011, and 2017), however, the vegetation cover increased for 17 springs, decreased for 11 springs, and was completely degraded for other two. To improve the performance of this PES, we recommend (1) expanding the program to include the APPs surrounding the springs, together with the legal reserves of each property, (2) implementing measures to ensure that properties are environmentally adequate, (3) including the properties in the Brazilian Rural Environment Register (CAR), and (4) obtaining environmental licensing for the activities undertaken within the Abóbora River basin.

Seasonal divergence of evapotranspiration sensitivity to vegetation changes – A proportionality-hypothesis-based analytical solution

Seasonal variation of vegetation profoundly affects the water cycle. However, the seasonal divergence of evapotranspiration (ET) sensitivity in response to vegetation variations has not been fully understood. Here we derived an analytical solution to examine the impact of seasonal vegetation changes on ET with an extended Budyko framework based on an improved ET algorithm with improved water balance constraints. Results reveal a clear seasonal divergence of ET sensitivity to vegetation coverage changes across climate regimes and biomes. Generally, the high ET sensitivity to vegetation coverage has a clear north-south shift trajectory from spring to winter. For moderate-humid regions (0.7 < aridity index < 1.0), vegetation exhibits higher importance in altering ET in March-September. While for moderate-dry regions (1.0 < aridity index < 1.4), the sensitivity of ET to vegetation changes is the highest in September-November. Moreover, the spatial-temporal pattern of ET sensitivity to seasonal vegetation changes is different between short vegetation cover and forest. Additionally, negative ET sensitivity to vegetation coverage changes was discovered in regions with seasonal precipitation of less than 500 mm and sparse vegetation coverage (predominant land cover types of grassland, scrubland, and savannas). In summary, our study provides an analytical solution to estimate ET sensitivity to seasonal vegetation changes within the extended Budyko framework. The results highlight the difference in hydrological response to vegetation dynamics across seasons and vegetation types.

Change Detection of Vegetative Covers in Kalara Nala Watershed of Damoh District Using Remote Sensing and GIS

Remote sensing and GIS technologies have proven to be effective tools to analyse land use land cover (LULC) changes on watershed basis. The evaluation and monitoring of watershed development programmes are of prime importance to assess the conservation of natural resources and the efficiency of their utilization. The investigation aims to detect changes in vegetative cover due to water harvesting and recharging structures of the study watershed situated in Patharia block of Damoh district, Madhya Pradesh. The watershed development programme was executed during the period 2018-2022. All the processes related to the evaluation of watershed development activities were performed using remote sensing and GIS tools through pre and post development data in the GIS environment. The change detection in vegetative cover was done based on land use land cover patterns. By adopting unsupervised classification approach, high-resolution satellite data of Sentinel-2B for the years 2018 and 2022 were used for land use land cover (LULC) mapping and further analysis. During the year 2018, it was observed that the vegetative cover in the watershed was 37% of the watershed area however after the implementation of the watershed development programme total vegetative cover increased to 60% of the total watershed area in the year 2022. From the study, it can be concluded that remote sensing and GIS can prove to be viable tool for the evaluation of watershed development programmes.

Vegetation cover variations associated with climate change and human activities in Nanjing metropolitan area of China.

Quantify the relative effects of climate change and human activities on vegetation cover can help us understand the vegetation cover change and its drivers. Residual analysis, defined as the difference between potential normalized difference vegetation index (NDVIpot) and observed normalized difference vegetation index (NDVIact), was used to solve this problem. The estimation of NDVIpot is one of the important issues faced by ecologists. Due to the strictly protection of environment and ecosystems, the ecosystems in nature reserves are rarely disturbed by human activities. Therefore, establishing NDVIpot estimation model based on nature reserves can improve the estimation accuracy of NDVIpot. However, the estimation of NDVIpot based on nature reserves has not yet been reported. In this paper, the NDVIpot estimation model was established based on nature reserves, and residual analysis was used to quantify the impact of human activities on NDVIact. The results show that the NDVIact in Nanjing metropolitan area (NJMA) showed a significant upward trend from 2000 to 2019, and 74.20% of NJMA showed greening trends, while 24.47% showed browning trends. The temperature and precipitation were positively correlated with normalized difference vegetation index (NDVI), and the impact of the temperature on NDVI was greater than that of precipitation. The promotion of human activities on NDVI had become more and more significant. There was 51.88% of NJMA where the human activities had a positive promotion effect on NDVI, while there was 46.29% of the regional where the human activities had a negative inhibitory effect on NDVI. The population density (POP) and gross domestic product (GDP) were mainly positively correlated with NDVI, and the impact of the POP on NDVI was greater than that of GDP. The conversion of cropland to forests and the increase of the sown area of crops also caused the NDVI to increase, while the disorderly expansion of urban land caused the NDVI to decrease.