Normalized Difference Vegetation Index‐based assessment of climate change impact on vegetation growth in the humid‐arid transition zone in northern China during 1982–2013

Abstract

As an ecologically sensitive region, the humid‐to‐arid climate transition zone in the eastern and central north China (ECNC) has experienced varied vegetation change in recent decades, but the exact impacts of climate change and human activities remain uncertain. Based on the Normalized Difference Vegetation Index (NDVI), we established the trend of vegetation change in the past three decades (1982–2013) in the ECNC, and examined the impact of climate and nonclimate factors on vegetation growth within the different eco‐regions. For the study period, the climate in ECNC became significantly warmer and slightly drier, and the overall NDVI increased significantly, but with great spatial variations. Our results suggest that temperature increase has promoted vegetation growth in places that are colder and/or wetter, and with higher vegetation coverage. Precipitation increase has promoted vegetation growth in drier places with sparse vegetation and inhibited growth in wet places with high vegetation coverage. As different eco‐regions typically have different vegetation coverage and occupy different climate zones, their response to climate change also varies. For the study period, increasing temperature and decreasing precipitation promoted vegetation growth in the forest of northern ECNC. Increasing temperature and precipitation led to NDVI increase in the grassland in the south, whereas grassland in the north and west showed no significant change despite temperature increase and precipitation decrease. Cropland responded mostly positively to temperature increase, although correlations between NDVI and climate factors were generally weaker. Using multiple regression models, we found that 60% of the NDVI increase was attributed to climate factors whereas the remaining 40% was likely caused by human activities. Although farming practices and crop rotations might have caused significant decrease in NDVI in small areas, human impact largely led to significant NDVI increase in the grass‐crop transition zones, most likely due to ecological restoration programs.

Spatiotemporal Pattern and Aggregation Effects of Poplar Canker in Northeast China

“…Considering that the actual host area and total incidence area of each county have no records available, we assumed the mean value of the maximum NDVI for each month from March to July (i.e., the period when trees are luxuriant, and poplar canker is prone to occur) to approximately represent vegetation coverage, as the positive relationship between NDVI and vegetation coverage [22]. It is a typical representation in regional geographic analyses [23,24]. Under the premise that a variety of host plants (around 59 species of Populus and Salix) are widely distributed in the study area, the vegetation coverage was approximately considered as the host vegetation coverage.…”

Projecting Future Vegetation Change for Northeast China Using CMIP6 Model

“…The greening of terrestrial ecosystems has been reported at both global and regional scales, usually based on long-term satellite-derived vegetation indexes compiled over the past several decades [5,6]. Previous studies have shown a general greening trend since the 1980s in NE China as a result of both a shift toward a warmer and wetter climate and human efforts, such as widespread restoration projects [7][8][9][10]. However, great uncertainties still exist as to whether this greening trend will continue in the future under projected climate change [11,12].…”

The sensitivity of vegetation in the lower Tigris basin landscapes to regional and global climate variability

“…Global climate change has the potential to increase the frequency of ecosystem disturbances such as fire and drought, threatening the terrestrial ecological environment and food security (Yuan, Wu, Hou, Xu & Lu, 2019). Most of the Euphrates-Tigris basin, especially in southeastern Turkey as well as in northern Syria and Iraq (the lower Tigris basin), has a Mediterranean climate that is characterized by wet winters and dry summers (Food and Agriculture Organization of the United Nations [FAO], 2009).…”

“…Since the 1970s, monitoring vegetation has been improved using several remote sensing-based indices. The normalized difference vegetation index (NDVI) (Tucker, 1979), specifically, is the most popular and has been used successfully to detect vegetation and climate conditions interactions worldwide at various temporal and spatial scales (Wu et al, 2015;Xu, Yang & Chen, 2016;Yuan et al, 2019;Luo, Mao, Wen & Liu, 2020). In the study of Luo et al (2020), the dynamic characteristics of drought characterized using the standardized precipitation evapotranspiration index (SPEI) and the NDVI were investigated and evaluated on an interannual scale from 1998 to 2015.…”

“…Two NDVI datasets were used in the work of Xu et al (2016) to study vegetation growth and its response to climate change reflected by the precipitation, minimum, maximum, and mean temperatures at yearly and monthly time scales from 1982 to 2013. Yuan et al (2019) established the trend of NDVI vegetation change in the past three decades and examined the effect of climate (monthly temperature and precipitation) and non-climate (population, gross domestic product, and live-stock) factors on vegetation growth. Note that the temporal delay in the vegetation response to environmental changes should be considered when looking for the sensitivity of ecosystems to climate variability (Wu et al, 2015).…”