The Response of Vegetation Phenology and Productivity to Drought in Semi-Arid Regions of Northern China

Abstract

A major disturbance in nature, drought, has a significant impact on the vulnerability and resilience of semi-arid ecosystems by shifting phenology and productivity. However, due to the various disturbance mechanisms, phenology and primary productivity have remained largely ambiguous until now. This paper evaluated the spatio-temporal changes of phenology and productivity based on GIMMS NDVI3g time series data, and demonstrated the responses of vegetation phenology and productivity to drought disturbances with the standardized precipitation evapotranspiration index (SPEI) in semi-arid ecosystems of northern China. The results showed that (1): vegetation phenology exhibited dramatic spatial heterogeneity with different rates, mostly presented in the regions with high chances of land cover type variation. The delayed onset of growing season (SOS) and advanced end of growing season (EOS) occurred in Horqin Sandy Land and the eastern Ordos Plateau with a one to three days/decade (p < 0.05) rate and in the middle and east of Inner Mongolia with a two days/decade rate, respectively. Vegetation productivity presented a clear pattern: south increased and north decreased. (2) Spring drought delayed SOS in grassland, barren/sparsely vegetated land, and cropland, while autumn drought significantly advanced EOS in grassland and barren/sparsely vegetated lands. Annual drought reduced vegetation productivity and the sensitivity of productivity regarding drought disturbance was higher than that of phenology.

Heterogeneous spring phenology shifts affected by climate: supportive evidence from two remotely sensed vegetation indices

“…The water stress can limit phenology response to the preseason daily maximum temperature (Shen et al 2016). The spring droughts can ever delay the spring phenology in grassland (Kang et al 2018).…”

Responses of Seasonal Indicators to Extreme Droughts in Southwest China

“…Regarding the influence of drought, response of vegetation to drought is one of hot topics. Some studies have documented the influence or recovery of drought to different types of vegetation, different periods of growth time, different stages of drought and different places [33][34][35][36]. For example, savannas, croplands and mixed forests were more vulnerable to drought than deciduous forests and grasslands, while evergreen forests were more resistant to droughts and even were not influenced in the early period of drought [10,36].…”

A Spatio-Temporal Analysis of Rainfall and Drought Monitoring in the Tharparkar Region of Pakistan

“…These variables include the start, length, and end of the growing season, drought periods, and the nature of rainfall, whether early, late, frequent, intense, or well-distributed. Such variables can potentially be mapped using satellite images and their trends identified [12][13][14]. However, different methodologies have been shown to give significantly different seasonal transition dates [14] and The increase in frequency and severity of droughts in recent decades reduced agricultural yield, leading to increased poverty and food insecurity.…”

“…Such variables can potentially be Remote Sens. 2020, 12, 580 3 of 16 mapped using satellite images and their trends identified [12][13][14]. However, different methodologies have been shown to give significantly different seasonal transition dates [14] and algorithms effective in one study area may not apply in others.…”

“…Since temperature is the most common limiting factor to growth, many studies used temperature thresholds to define growing season days such as daily average above 5 • C [16]. Landscapes in more arid regions and/or those with low seasonal amplitude of vegetation indices were shown by several studies to give the lowest agreement between satellite normalized difference vegetation index (NDVI) and ground-measured phenology [12][13][14]. Kang et al [12] also demonstrated uncertainty in phenology measurement arising from the spatial resolutions of different satellite sensors.…”