CRC TRR 228 Project A01
Future Carbon Storage
Synergies and trade-offs of carbon storage along pathways of land transformation
A01 Future Carbon Storage
Vision
Improve our understanding of how heterogeneous patterns of rural wealth interact with the natural resource base, and to what extent environment constrains future development possibilities.
Project Summary
This interdisciplinary project continues to view the future-making in rural Africa through a carbon lens, focusing on two conflicting visions: wildlife conservation and agricultural intensification.
During Phase I, we have used space-for-time substitutions and combined biophysical and socio-economic data at different scales to analyse effects of conservation and intensification on (1) carbon-stock dynamics in soil and vegetation and carbon-related ecosystem services, (2) the composition of farm-household income, including detailed environmental sources. At the local scale of ecological observation plots we were able to show that carbon losses in the vegetation due to increased densities of large herbivores can be offset by carbon gains in soils. Surprisingly, soil carbon stocks under agriculture were not smaller than under conservation. This phenomenon may be driven by two aspects of farmers’ future-making: a future-oriented soil fertility management, and a preferential selection of fertile land for agriculture. The implications for respective social-ecological coupling will be further explored in Phase II. At the regional scale, we found that Community-Based Natural Resource Management (CBNRM), although positively affecting the presence of large herbivores, also led to net losses in carbon-dense woodland cover in the region. We assume that the heterogeneous impacts of CBNRM are driven by tourism opportunities. In sub-regions with relevant wildlife presence, wildlife conservation has synergistic effects on woodland cover, while in regions without opportunities for tourism, agriculture-dominated livelihood strategies have detrimental effects on vegetation cover and corresponding carbon storage.
In Phase II, we will address three hypotheses, keeping carbon as the common currency within our project. We aim to understand how (1) historical settlement processes have co-determined current land-access and land-use patterns, as well as related rural wealth dynamics and variations in soil and vegetation quality. At the farm scale, we plan to study how (2) farmers actively shape their future by spatially modulating land management to improve soil and vegetation quality in the vicinity of their farms. At the regional scale and beyond, we will finally analyse (3) to what extent external shocks (e.g. COVID-19 pandemic) and spatio-temporal variations in policy regimes affect biophysical and socio-economic outcomes.
Research Regions: KAZA TFCA
Problem Statement
We investigate social-ecological coupling mechanisms involved in three ongoing transformation pathways: conservation, agricultural intensification, and restoration. Potential impacts of these transformations are investigated both on the socio-economic and bio-physical level as they are expected to concurrently change e.g. rural welfare, carbon sequestration, and other ecosystem services.
Key Questions
How is rural farm-household wealth related to soil and vegetation quality and carbon storage under consideration of interactions with wildlife?
Hypothesis H1: Lack of bargaining power among poor and marginalized rural population groups during historical settlement processes partially explains current correlations between inherent (permanent) soil properties and rural wealth.
Hypothesis H2: At the farm scale, the spatial modulation of soil and vegetation characteristics via a future-oriented farm management depends on wealth and investment constraints.
Hypothesis H3: At the village and regional scale (and beyond), external factors such as economic shocks, policies and non-agricultural income flows shape rural households’ future-making, and thus their interactions with soils, vegetation, and wildlife.
Methodology
Our methodological approach to answer these questions relies on primary data from soil and vegetation samples as well as on household survey data and remote sensing analyses.
Key Findings from Phase I
Unfortunately, current methods to quantify woody biomass and the carbon stored therein are not well-suited for ecosystems that are shaped by frequent disturbances such as elephant browsing. In Phase I, we thus developed a novel methodology to estimate woody biomass and carbon in disturbed dryland ecosystems. The methodological toolbox also comprises a detailed damage assessment, harnessing the ecological archive of trees for past disturbances. Results indicate that in highly disturbed African savannas, previous methods may underestimate woody biomass and the C (carbon) stored therein by up to 90 %. With the aid of this novel methodology, we were able to attribute elephant browsing in Namibia’s KAZA area to reduced C storage in woody biomass by 6.4 t C ha-1. However, the soil science team found that these C losses were almost compensated by increased C storage in soils (4.7 t C ha-1). Hence, rewilding with elephants seems to only have marginal effects on total carbon storage. With increasing elephant densities, though, community composition changed considerably, hinting at a non-linear relationship between conservation and biodiversity.
Intensification efforts are preferably focused on areas, which are relatively rich in soil organic matter and clay content, contain even more C than is lost with cultivation, thus raising novel questions about how these sites were selected by local farmers. At a regional scale, community-based natural resource management (CBNRM), the dominant conservation strategy in Namibia, reduced woodland cover by 2.1% between 1994 and 2009, corresponding to an annual change of -0.14% (Meyer et al., 2021). Heterogeneous treatment effect analysis indicated that CBNRM does work for woodland conservation when communities are in and around wildlife corridors, which provide tourism income opportunities. Inside these wildlife corridors, disturbance from wildlife may still exert negative effects on woody vegetation, but not to the extent of neutralizing the gains from conservation action.
Our joint research indicated that land-use decisions at household and community levels are the main drivers of change in aboveground and belowground carbon dynamics and related ecosystem services. However, the Spatio-temporal movement patterns of large herbivores are clearly co-determined by political decisions at national or regional levels, which significantly also affect the environmental outcomes. Rural wealth varies considerably within and between villages, and CRC228 household survey data collected in 2019 suggests a significant correlation with remotely sensed vegetation biomass.
Relation to the CRC
The project scopes the possible range of outcomes and identifies probable future development pathways. Our research integrates across soil, vegetation, and social sciences in collaboration with other CRC projects.
Publications
Börner, J., Schulz, D., Wunder, S., Pfaff, A. 2020. The effectiveness of forest conservation policies and programs. Annual Review of Resource Economics 12:45-64. Link
Duarte-Guardia, S., Peri, P., Amelung, W., Thomas, E., Borchard, N., Baldi, G., Cowie, A. & Ladd, B. 2020. Biophysical and socioeconomic factors influencing soil carbon stocks: a global assessment. Mitigation and Adaptation Strategies for Global Change: 1-20. DOI
Ferner, J., Schmidtlein, S., Guuroh, R. T., Lopatin, J., Linstädter, A. 2018. Disentangling effects of climate and land-use change on West African drylands’ forage supply. Global Environmental Change, 53, 24 – 38. DOI
Gaitán, J. J., Maestre, F. T., Bran, D. E., Buono, G. G., Dougill, A. J., García Martínez, G., Ferrante, D., Guuroh, R. T., Linstädter, A., Massara, V., Thomas, A. D., Oliva, G. E. 2019. Biotic and Abiotic Drivers of Topsoil Organic Carbon Concentration in Drylands Have Similar Effects at Regional and Global Scales. Ecosystems. Link
Kalvelage, L., Bollig, M., Grawert, E., Hulke, C., Meyer, M., Mkutu, K., Müller-Koné, M., Revilla Diez, J. 2021. ‘Territorialising Conservation: Community-based Approaches in Kenya and Namibia’, Conservation and Society. Access Link
Kiesel, C., Dannenberg, P., Hulke, C., Kairu, J., Revilla Diez, J., Sandhage-Hofmann, A. 2022. ‘An argument for place-based policies: The importance of local agro-economic, political and environmental conditions for agricultural policies exemplified by the Zambezi region, Namibia’, Environmental Science & Policy, vol. 129, pp. 137-149. DOI
Kindermann, L., Dobler, M., Niedeggen, D., Linstädter, A. 2022. ‘A new protocol for estimation of woody aboveground biomass in disturbance-prone ecosystems’, Ecological Indicators, vol 135, no. 108466. DOI
Kindermann, L., Dobler, M., Niedeggen, D., Fabiano, E.C., Linstädter, A. 2022. Dataset on Woody Aboveground Biomass, Disturbance Losses, and Wood Density from an African Savanna Ecosystem. Data in Brief, 108155. DOI
Kindermann, L., Dobler, M., Niedeggen, D., Linstädter, A. 2020. Improving estimation of woody aboveground biomass in drylands by accounting for disturbances and spatial heterogeneity. DOI, Preprint, in review with Ecological Indicators.
Luedeling, E., J. Börner, Amelung, W., Schiffers, K., Shepherd, K., and Rosenstock, T. 2019. Forest restoration: Overlooked constraints. Science 366: 315-315. Link
Meyer, M., Hulke, C., Kamwi, J., Kolem, H., Börner, J. 2022. ‘Spatially heterogeneous effects of collective action on environmental dependence in Namibia’s Zambezi region‘, World Development, Vol. 159, 106042. DOI
Meyer, M., Börner, J. 2022. ‘Rural livelihoods, community-based conservation, and human-wildlife conflict: Scope for synergies?‘, Biological Conservation, Volume 272. Full Text
Meyer, M., Klingelhoeffer, E., Naidoo, R., Wingate, V., Börner, J. 2021. Tourism opportunities drive woodland and wildlife conservation outcomes of community-based conservation in Namibia’s Zambezi Region. Ecological Economics 180: 106863. Link
Munjonji, L., Ayisi, K. K., Mudongo, E. I., Mafeo, T. P., Behn, K., Mokoka, M. V., Linstädter, A. 2020. Disentangling Drought and Grazing Effects on Soil Carbon Stocks and CO2 Fluxes in a Semi-Arid African Savanna. Frontiers in Environmental Science, 1 – 14. DOI
Mutwale-Mutale, N., Jorge, F., Chabala, L.M., Shepande, C., Chishala, B.H., Cambule, A., Nhantumbo, A., Matangue, M., Braun, M., Sandhage-Hofmann, A. and Amelung, W. 2023. Climatic effects on soil phosphorus pools and availability in sub-Saharan Africa. Eur J Soil Science. DOI
Sandhage-Hofmann, A. 2023. Rangeland management. In: Goss, Michael and Oliver, Margaret (eds.) Encyclopedia of Soils in the Environment. Vol. [1], pp. 88-101. Oxford: Elsevier.
Sandhage-Hofmann, A. 2022. Rangeland Management. In: Reference Module in Eearth Systems and Environmental Sciences. Elsevier, Amsterdam. Link
Sandhage-Hofmann, A., Angombe, S., Kindermann, L., Linstädter, A., Mörchen, R. 2022. ‘Conservation with elephants and agricultural intensification: effects on lignin and n-alkanes in soils of sub-Saharan Africa‘, Geoderma, Vol. 425, 116009. DOI
Sandhage-Hofmann, A., J. Löffler, E. Kotzé, S. Weijers, V. Wingate, D. Wundram, L. Weihermüller, R. Pape, C.C du Preez, and Amelung, W. 2020. Woody encroachment and related soil properties in different tenure-based management systems of semiarid rangelands. Geoderma 372:114399. DOI
Sandhage-Hofmann, A., Linstädter, A., Kindermann, L., Angombe, S., Amelung, W. 2021. ‘Conservation with elevated elephant densities sequesters carbon in soils despite losses of woody biomass’ Global Change Biology, Vol 27, Issue 19, pp 4601- 4614. DOI
Tabe-Ojong, M.P., Gebrekidan, B.H., Nshakira-Rukundo, E., Börner, J., & Heckelei, T. 2022. ‘COVID-19 in rural Africa: Food access disruptions, food insecurity and coping strategies in Kenya, Namibia, and Tanzania‘, Agricultural Economics, pp. 1– 20. DOI
Zimmer, K., Amputu, V., Schwarz, L.-M-, Linstädter, A., Sandhage-Hofmann, A. 2024. Soil characteristics within vegetation patches are sensitive indicators of savanna rangeland degradation in central Namibia, Geoderma Regional, Volume 36, e00771, DOI
Project News
Soil characteristics within vegetation patches are sensitive indicators of savanna rangeland degradation in central Namibia
Publication: Climatic Effects on Soil Phosphorus Pools and Availability in Sub-Saharan Africa
[DE] “Future Rural Africa” im Potsdamer Universitätsmagazin “Portal”: Zukunftsvisionen für das ländliche Afrika – Über Landwirtschaft, Naturschutz und die Savanne als Kohlenstoffspeicher
CRC-TRR Future Rural Africa at ECAS 2023
