Revisiting the cumulative effects of drought on global gross primary productivity based on new long‐term series data (1982–2018)

Abstract

Drought has broad and deep impacts on vegetation. Studies on the effects of drought on vegetation have been conducted over years. Recently, the cumulative effect of drought is recognized as another key factor affecting plant growth. However, globalscale studies on this phenomenon are still lacking. Thus, based on new satellite based gross primary productivity (GPP) and multi-temporal scale Standardized Precipitation Evapotranspiration Index data sets, we explored the cumulative effect duration (CED) of drought on global vegetation GPP and analyzed its variability across elevations and climatic zones. The main findings were as follows: (1) The cumulative effect of drought on GPP was widespread, with an average CED of 4.89 months. (2) CED of drought on GPP varied among vegetation types. Specifically, grasslands showed the longest duration, with an average value of 5.28 months, followed by shrublands (5.09 months), wetlands (5.03 months), croplands (4.85 months), savannas (4.58 months), and forestlands (4.57 months). (3) CED of drought on GPP changes with climate conditions. It decreased with the decrease of precipitation in the driest month (P dry ) and mean annual precipitation in tropical and arid climate zones, respectively. In both temperate and cold climate zones, CED of drought on GPP was shorter in areas with dry winter than that in areas with dry summer. It increased with the decrease of mean annual air temperature in tropical climate zones and decreased with the increase of summer temperature in temperate and cold climatic zones. (4) With increasing elevation, CED of drought on GPP showed a pattern of increasing (0-3000 m), then decreasing (3000-5000 m), and increasing again (>5000 m). Our findings highlight the heterogeneity of CED of drought on GPP, owing to differences in vegetation types, long-term hydrothermal conditions, elevation, etc. The results could deepen our understanding of the effects of drought on global vegetation.

Drought legacies and ecosystem responses to subsequent drought

“…In grasslands, most C‐cycle related legacies return to pre‐disturbance level roughly within the first year after the drought and can last several years for forests (Figure 3a). This is in line with the suggestion by Wu et al (2018), and Zhang et al (2022) that drought legacies tend to be longer for forest and woody species compared to grasslands and non‐woody/herbaceous species.…”

Soil moisture determines the recovery time of ecosystems from drought

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Drought refers to the climate extreme caused by moisture deficiency that affects the hydrological cycle, increases the risk of forest death, causes land degradation and even reduces the biodiversity of terrestrial ecosystems (Sturm et al, 2022;Vicente-Serrano et al, 2020;Zhang et al, 2022). Previous research pointed that negatively affected by warm drought, negative gross primary productivity (GPP) extremes of northern mid-latitude ecosystems increased by 10.6% in 2000-2016 compared with the period from 1982 to 1998 (Gampe et al, 2021), which greatly weakened the carbon sink of ecosystems and increased the risks to ecosystems.

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Probabilistic assessment of drought stress vulnerability in grasslands of Xinjiang, China

“…In addition to climatic factors, other environmental factors (e.g., elevation, slope and aspect) can influence the drought patterns in a region ( Kumari et al., 2020 ). Because elevation is a direct control factor affecting temperature, slope orientation affects solar exposure time and solar radiation (P. Zhang et al., 2022 ), both of which are important factors affecting vegetation drought ( Yang et al., 2022 ). The only highly significant correlation (r = -0.52519) found in our study was between elevation and the probability of meadow decline to the 30th percentile of the land during severe drought, with a smaller effect of slope and slope orientation on meadow drought ( Figure 15 ).…”