Dryland Vegetation Functional Response to Altered Rainfall Amounts and Variability Derived from Satellite Time Series Data

Ratzmann, Gregor; Gangkofner, Ute; Tietjen, Britta; Fensholt, Rasmus

doi:10.3390/rs8121026

Cited by 14 publications

(8 citation statements)

References 77 publications

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“…9d), and hence spatio-temporal changes in rainfall intensity (but characterized by the same amount of seasonal rainfall) will impact vegetation productivity. This has important implications for the use of the rain use efficiency (RUE) (Houerou, 1984) or residual trend analysis (RESTREND) approach (regressing NDVI from annual precipitation and subsequently calculating the residuals as the difference between observed NDVI and NDVI as predicted from annual precipitation) (Evans and Geerken, 2004), which is derived from annually or seasonally summed rainfall and commonly used as an indicator for land degradation (Archer, 2004;Bai et al, 2008;Fensholt and Kjeld, 2011;Prince et al, 1998;Ratzmann et al, 2016;Wessels et al, 2007) as discussed in Ratzmann et al (2016). Interestingly, a limited impact of rainfall seasonality on growing season ANPP was found in arid lands below 300 mm yr −1 rainfall, suggesting that the species composition was adapted to rainfall variation and that the rather sparse vegetation cover was able to effectively utilize rainfall independent of the seasonal distribution.…”

Section: Discussionmentioning

confidence: 99%

Impacts of the seasonal distribution of rainfall on vegetation productivity across the Sahel

et al. 2018

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Abstract. Climate change in drylands has caused alterations in the seasonal distribution of rainfall including increased heavy-rainfall events, longer dry spells, and a shifted timing of the wet season. Yet the aboveground net primary productivity (ANPP) in drylands is usually explained by annual-rainfall sums, disregarding the influence of the seasonal distribution of rainfall. This study tested the importance of rainfall metrics in the wet season (onset and cessation of the wet season, number of rainy days, rainfall intensity, number of consecutive dry days, and heavy-rainfall events) for growing season ANPP. We focused on the Sahel and northern Sudanian region (100-800 mm yr −1 ) and applied daily satellite-based rainfall estimates (CHIRPS v2.0) and growing-season-integrated normalized difference vegetation index (NDVI; MODIS) as a proxy for ANPP over the study period: 2001-2015. Growing season ANPP in the arid zone (100-300 mm yr −1 ) was found to be rather insensitive to variations in the seasonal-rainfall metrics, whereas vegetation in the semi-arid zone (300-700 mm yr −1 ) was significantly impacted by most metrics, especially by the number of rainy days and timing (onset and cessation) of the wet season. We analysed critical breakpoints for all metrics to test if vegetation response to changes in a given rainfall metric surpasses a threshold beyond which vegetation functioning is significantly altered. It was shown that growing season ANPP was particularly negatively impacted after > 14 consecutive dry days and that a rainfall intensity of ∼ 13 mm day −1 was detected for optimum growing season ANPP. We conclude that the number of rainy days and the timing of the wet season are seasonal-rainfall metrics that are decisive for favourable vegetation growth in the semiarid Sahel and need to be considered when modelling primary productivity from rainfall in the drylands of the Sahel and elsewhere.

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Section: Discussionmentioning

confidence: 99%

Impacts of the seasonal distribution of rainfall on vegetation productivity across the Sahel

et al. 2018

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“…Vegetation productivity in drylands is related to the soil-water status [37]. Therefore, the significantly and almost tenfold higher value for mean cover by the predominant shrub species (H. scoparium) in intact-terrace plots, compared to collapsed-terrace plots (Table 1), is attributed to the effective harvest of runoff water in the former, compared to the leaking of runoff water through gaps in the plots' downslope terraces in the latter.…”

Section: Ground Surface Cover and Implications For Surface Processesmentioning

confidence: 99%

Failure and Collapse of Ancient Agricultural Stone Terraces: On-Site Effects on Soil and Vegetation

Stavi

Rozenberg

Al-Ashhab

et al. 2018

Water

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Ancient agricultural stone terraces, dated to the Roman and Byzantine ages, are prevalent across the Negev drylands of Southern Israel. The goal of these structures was to reduce hydrological connectivity by harvesting water runoff and controlling soil erosion, thus allowing cultivation of cereals. Land abandonment and the lack of maintenance have led to the failure and collapse of many of these stone terraces. The objective of this study was to assess the effect of failure and collapse of terraces on the on-site (on-field) geo-ecosystem functioning, as determined by vegetation cover and soil quality parameters. This was achieved by studying vegetal and soil properties in shrubby vegetation patches and inter-shrub spaces of intact-terrace plots and collapsed-terrace plots, as well as in the surrounding ‘natural’ lands. Mean cover of both shrubby and herbaceous vegetation was highest in intact terraces, intermediate in ‘natural’ lands, and lowest in collapsed terraces. The overall soil quality followed the same trend as the vegetation cover. Additionally, this study shows that the anthropogenic impact on geo-ecosystem functioning can be either beneficial or detrimental. While well maintained stone terraces benefit the soil and vegetation, abandoned and unmaintained terraces may result in accelerated soil erosion and land degradation.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Shi

Wang

Zhang

et al. 2018

Hydrological Processes

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Rainfall is considered as the dominant water replenishment in desert ecosystems, and the conversion of rainfall into soil water availability plays a central role in sustaining the ecosystem function. In this study, the role of biological soil crusts (BSCs), typically formed in the revegetated desert ecosystem in the Tengger Desert of China, in converting rainfall into soil water, especially for the underlying soil moisture dynamics, was clarified by taking into account the synthetic effects of BSCs, rainfall characteristics, and antecedent soil water content on natural rainfall conditions at point scale. Our results showed that BSCs retard the infiltration process due to its higher water holding capacity during the initial stage of infiltration, such negative effect could be offset by the initial wet condition of BSCs. The influence of BSCs on infiltration amount was dependent on rainfall regime and soil depth. BSCs promoted a higher infiltration through the way of prolonged water containing duration in the ground surface and exhibited a lower infiltration at deep soil layer, which were much more obvious under small and medium rainfall events for the BSCs area compared with the sand area. Generally, the higher infiltration at top soil layer only increased soil moisture at 0.03 m depth; in consequence, there was no water recharge for the deep soil, and thus, BSCs had a negative effect on soil water effectiveness, which may be a potential challenge for the sustainability of the local deep‐rooted vegetation under the site specific rainfall conditions in northwestern China.

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Dryland Vegetation Functional Response to Altered Rainfall Amounts and Variability Derived from Satellite Time Series Data

Cited by 14 publications

References 77 publications

Impacts of the seasonal distribution of rainfall on vegetation productivity across the Sahel

Impacts of the seasonal distribution of rainfall on vegetation productivity across the Sahel

Failure and Collapse of Ancient Agricultural Stone Terraces: On-Site Effects on Soil and Vegetation

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

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