Dryland vegetation functional response to altered rainfall amounts and variability derived from satellite time series data

Abstract

Abstract. Vegetation net productivity is a key variable in ecosystem functioning. Understanding how its functional response to rainfall in drylands is affected by altered rainfall amounts and variability is therefore vitally important to understand consequences of climatic change for those water-limited ecosystems. Here, we show how this functional response is affected by below and above 30-year-average rainfall conditions in two arid to semi arid subtropical regions in West and South West during dry periods for mean annual precipitation < 500 mm and spatially more variable, the responses to climate for West Africa are generally low and spatially less dynamic. Those patterns follow differences in interannual rainfall amount variability (higher in South West Africa). Regional peaks of vegetation response to rainfall along mean annual precipitation are found at precipitation values with similar interannual variability in growing season length. Vegetation type (MODIS MCD12C) specific response to rainfall mostly follows observed responses along rainfall gradients leading to region specific 25 responses for each vegetation type. We conclude that higher rainfall amount variability enhances regional-scale vegetation response to rainfall plasticity and thus dryland ecosystem resilience to dry periods. Those results apply irrespective of vegetation type and thus evidence the fundamental role of rainfall variability in ecosystem functioning. Presented results moreover imply that the Sahel region (West Africa) although currently recovering from drought might be highly susceptible to future dry periods. 30

Estimation des rendements fourragers des pâturages dans les espaces climatiques du Burkina Faso à partir de données satellitaires

“…Au Burkina Faso, la densité de la végétation ligneuse diminue avec le gradient pluviométrique, à l'exception des zones de conservation forestière qui présentent une densité plus importante (Fontes et Guinko, 1995). La végétation herbacée est dominée par les herbacées annuelles et les cultures annuelles (Ratzmann et al, 2016 ;Abdi et al, 2017).…”

The effect of biological soil crusts on soil moisture dynamics under different rainfall conditions in the Tengger Desert, China

“…Desert ecosystem is characterized as a water‐limited ecosystem with low water input (Noy‐Meir, ). In desert ecosystems, soil moisture, especially soil water availability, is of critical importance in sustaining ecological processes and vegetation dynamics (Loik, Breshears, Lauenroth, & Belnap, ; Ratzmann, Gangkofner, Tietjen, & Fensholt, ; Zhang, Zhao, Liu, Fang, & Feng, ). Therefore, the reasonable management of limited rainfall into soil water has always been the central issue in arid desert areas.…”