Modeling the multi‐functionality of African savanna landscapes under global change

Rötter, Reimund P.; Scheiter, Simon; Hoffmann, Munir P.; Pfeiffer, Mirjam; Nelson, William; Ayisi, Kingsley Kwabena; Taylor, Peter J.; Feil, Jan‐Henning; Bakhsh, Sara Yazdan; Isselstein, J.; Lindstädter, Anja; Behn, Kai; Westphal, Catrin; Odhiambo, Jude J. O.; Twine, Wayne; Graß, Ingo; Merante, Paolo; Bracho‐Mujica, Gennady; Bringhenti, Thomas; Lamega, Sala; Abdulai, Issaka; Lam, Q.D.; Anders, Mina; Linden, Valerie M.G.; Weier, Sina M.; Foord, Stefan H.; Erasmus, Barend

doi:10.1002/ldr.3925

Cited by 11 publications

(7 citation statements)

References 20 publications

(37 reference statements)

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“…Targeted experimental work and environmental monitoring allows for the evaluation of model components for new scenarios. Subsequently, an updated integrative modeling framework, as suggested by Rötter et al (2021), can be applied to test different climate change and management scenarios. Further development should include an animal physiology model to simulate the dynamics of animal growth, reproduction, and health condition based on nutrition status.…”

Section: Discussionmentioning

confidence: 99%

“…Average daily maximum temperatures are 30.6 and 32.4 • C in January and 24.3 and 25.9 • C in July for Gabaza and Selwana, respectively (Table 1). Both villages are part of research projects (SALLnet, Rötter et al, 2021, https://www.uni-goettingen.de/en/ 592566.html, last access: 24 August 2022) and have been under survey since 2013 (Table 1).…”

Section: Study Regionmentioning

confidence: 99%

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Modeling the effects of alternative crop–livestock management scenarios on important ecosystem services for smallholder farming from a landscape perspective

Pfeiffer

Hoffmann²,

Scheiter³

et al. 2022

Biogeosciences

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Abstract. Smallholder farming systems in southern Africa are characterized by low-input management and integrated livestock and crop production. Low yields and dry-season feed shortages are common. To meet growing food demands, sustainable intensification (SI) of these systems is an important policy goal. While mixed crop–livestock farming may offer greater productivity, it implies trade-offs between feed supply, soil nutrient replenishment, soil carbon accumulation, and other ecosystem functions (ESFs) and ecosystem services (ESSs). Such settings require a detailed system understanding to assess the performance of prevalent management practices and identify potential SI strategies. Models can evaluate different management scenarios on extensive spatiotemporal scales and help identify suitable management strategies. Here, we linked the process-based models APSIM (Agricultural Production Systems sIMulator) for cropland and aDGVM2 (Adaptive Dynamic Global Vegetation Model) for rangeland to investigate the effects of (i) current management practices (minimum input crop–livestock agriculture), (ii) an SI scenario for crop production (with dry-season cropland grazing), and (iii) a scenario with separated rangeland and cropland management (livestock exclusion from cropland) in two representative villages of the Limpopo Province, South Africa, for the period from 2000 to 2010. We focused on the following ESFs and ESSs provided by cropland and rangeland: yield and feed provision, soil carbon storage, cropland leaf area index (LAI), and soil water. Village surveys informed the models of farming practices, livelihood conditions, and environmental circumstances. We found that modest SI measures (small fertilizer quantities, weeding, and crop rotation) led to moderate yield increases of between a factor of 1.2 and 1.6 and reduced soil carbon loss, but they sometimes caused increased growing-season water limitation effects. Thus, SI effects strongly varied between years. Dry-season crop residue grazing reduced feed deficits by approximately a factor of 2 compared with the rangeland-only scenario, but it could not fully compensate for the deficits during the dry-to-wet season transition. We expect that targeted deficit irrigation or measures to improve water retention and the soil water holding capacity may enhance SI efforts. Off-field residue feeding during the dry-to-wet season transition could further reduce feed deficits and decrease rangeland grazing pressure during the early growing season. We argue that integrative modeling frameworks are needed to evaluate landscape-level interactions between ecosystem components, evaluate the climate resilience of landscape-level ecosystem services, and identify effective mitigation and adaptation strategies.

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Section: Discussionmentioning

confidence: 99%

Section: Study Regionmentioning

confidence: 99%

Modeling the effects of alternative crop–livestock management scenarios on important ecosystem services for smallholder farming from a landscape perspective

Pfeiffer

Hoffmann²,

Scheiter³

et al. 2022

Biogeosciences

Self Cite

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“…Although Gabaza and Mafarana are neighbouring villages and have the same climate we treat them as different due to soil variability. All villages are part of an ongoing research project SALLnet (www.unigoettingen.de/de/592566.html) (Rötter et al 2021). All research activities within the project relevant to the results presented were approved by the ethical research committee at the University of Limpopo (UL).…”

Section: Case Study Region: Climatic Conditions and Cropping Systemmentioning

confidence: 99%

Tackling climate risk to sustainably intensify smallholder maize farming systems in southern Africa

Nelson

Hoffmann²,

May

et al. 2022

Environ. Res. Lett.

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Sustainable intensification (SI) of low input farming systems is promoted as a strategy to improve smallholder farmer food security in southern Africa. Using the Limpopo province South Africa as a case study (four villages across a climate gradient), we combined survey data (140 households) and quantitative agronomic observations to understand climate-induced limitations for SI of maize-based smallholder systems. Insights were used to benchmark the agroecosystem model APSIM, which was setup to ex ante evaluate technology packages (TPs) over 21-seasons (1998-2019): TP1 Status quo (no input, broadcast sowing), TP2 Fertiliser (micro dosing), TP3 Planting density (recommended), TP4 Weeding (all removed), TP5 Irrigation, TP6 Planting date (early, recommended), and TP6 All combined (TPs 1 to 5). An additional TP7 (Forecasting) investigated varying planting density and fertiliser in line with weather forecasts. Input intensity levels were low and villages expressed similar challenges to climate risk adaptation, with strategies mostly limited to adjusted planting dates and densities, with less than 2% of farmers having access to water for irrigation. Simulations showed that combining all management interventions would be expected to lead to the highest mean maize grain yields (3200 kg ha-1 across villages) and the lowest harvest failure risk compared to individual interventions. Likewise, simulations suggested that irrigation alone would not result in yield gains and simple agronomic adjustments in line with weather forecasts indicated that farmers could expect to turn rainfall variability into an opportunity well worth taking advantage of. Our study emphasises the need for a cropping systems approach that addresses multiple crop stresses simultaneously.

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“…Thus, the information previously derived from isotope analyses could be extended to draw conclusions on feed digestibility as a second approach to feed OMD in semiarid rangeland-based diets. We assume that comparisons of faecal isotopic signatures are a potential indicator to assess the nutritive feed value, and we present the first results of a positive correlation between OMD and faecal 15 N and the inverse relationship for OMD and faecal 13 C. This case study as part of the ongoing research project SALLnet ( [42]) and draws from fieldwork on private ranches and communal rangelands in semiarid South Africa. The work complements information on the above indicators with social perceptions to elicit the magnitude of drought-feed deficits and the differential perceptions of challenges related to drought between two social classes of livestock farmers.…”

Section: Of 14mentioning

confidence: 99%

Drought-Induced Challenges and Different Responses by Smallholder and Semicommercial Livestock Farmers in Semiarid Limpopo, South Africa—An Indicator-Based Assessment

2022

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Increased seasonal climatic variability is a major contributor to uncertainty in livestock-based livelihoods across Southern Africa. Erratic rainfall patterns and prolonged droughts have resulted in the region being identified as a climate ‘vulnerability hotspot’. Based on fieldwork conducted in the dry seasons in a semiarid region of South Africa, we present an interdisciplinary approach to assess the differential effects of drought on two types of livestock systems. Organic matter digestibility, faecal crude protein, C/N ratio and the natural abundance of faecal 15N and 13C isotopes were used as ecophysiological feed quality indicators between smallholder and semicommercial systems. These measurements were complemented with qualitative surveys. In a novel approach, we tested the potential of the isotopic signature to predict feed quality and present a significant relationship between organic matter digestibility and isotopic ratios. Indicators assessed smallholder feed quality to be significantly higher than semicommercial feed. However, animals from semicommercial farms were in significantly better condition than those from smallholding farms. Differential access to feed resources suggests that a complex feed–water–land nexus pushes smallholders into high reliance on off-farm supplements to bridge drought-induced feed deficits. The paper thus offers a contribution to intersectional work on drought effects on livestock keepers of semiarid South Africa and illustrates how ecophysiological indicators mirror socioeconomic differences.

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Modeling the multi‐functionality of African savanna landscapes under global change

Cited by 11 publications

References 20 publications

Modeling the effects of alternative crop–livestock management scenarios on important ecosystem services for smallholder farming from a landscape perspective

Modeling the effects of alternative crop–livestock management scenarios on important ecosystem services for smallholder farming from a landscape perspective

Tackling climate risk to sustainably intensify smallholder maize farming systems in southern Africa

Drought-Induced Challenges and Different Responses by Smallholder and Semicommercial Livestock Farmers in Semiarid Limpopo, South Africa—An Indicator-Based Assessment

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