Sphagnum-dominated peatlands head the list of ecosystems with the largest known reservoirs of organic carbon (C). The bulk of this C is stored in decomposition-resistant litter of one bryophyte genus: Sphagnum. Understanding how Sphagnum litter chemistry controls C mineralization is essential for understanding potential interactions between environmental changes and C mineralization in peatlands. We aimed to separate the effects of phenolics from structural polysaccharides on decay of Sphagnum. We measured aerobic microbial respiration of different moss litter types in a lab. We used chemical treatments to step-wise remove the chemical compounds thought to be important in decay-resistance in three taxonomically distant moss genera. We also focused on the effect of Sphagnum-specific cell-wall pectin-like polysaccharides (sphagnan) on C and N mineralization. Removing polymeric lignin-like phenolics had only negligible effects on C mineralization of Sphagnum litter, but increased mineralization of two other bryophyte genera, suggesting a minor role of these phenolics in decay resistance of Sphagnum but a major role of cell-wall polysaccharides. Carboxyl groups of pectin-like polysaccharides represented a C-source in non-Sphagnum litters but resisted decay in Sphagnum. Finally, isolated sphagnan did not serve as C-source but inhibited C and N mineralization instead, reminiscent of the effects reported for phenolics in other ecosystems. Our results emphasize the role of polysaccharides in resistance to, and active inhibition of, microbial mineralization in Sphagnum-dominated litter. As the polysaccharides displayed decay-inhibiting properties hitherto associated with phenolics (lignin, polyphenols), it raises the question if polysaccharide-dominated litter also shares similar environmental controls on decomposition, such as temperature or nutrient and water availability.

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Large uncertainties about the impacts of climate change and adaptation options on the livestock component of heterogeneous African farming systems hamper tailored decision making towards climate-smart agriculture. This study addressed this knowledge gap through the development and use of a dynamic modelling framework integrating climate, crop, pasture and livestock models. The framework was applied to a population of 91 farms located in semi-arid Zimbabwe to assess effects on livestock production resulting from climate change and management interventions. Climate scenarios representing relative "cool-wet", "hot-dry" and "middle" conditions by mid-century (2040-2070) for two representative concentration pathways were compared with the baseline climate. On-farm fodder resources and rangeland grass production were simulated with the crop model APSIM and the pasture model GRASP respectively. The simulated fodder availability was used in the livestock model LIVSIM to generate various production indicators including milk, offtake, mortality, manure, and net revenue. We investigated the effects of two adaptation packages targeting soil fertility management and crop diversification and quantified the sensitivity to climate change of both current and improved systems. Livestock productivity was constrained by dry-season feed gaps, which were particularly severe for crude protein and caused by the reliance on rangeland grazing and crop residues, both of low quality in the dry season. Effects on grass and stover production depended on the climate scenario and the crop, but year-to-year variation generally increased. Relative changes in livestock net revenue compared to the baseline climate varied from a 6% increase to a 43% decrease, and the proportion of farmers negatively affected varied from 20% to 100%, depending on the climate scenario. Adverse effects of climate change on average livestock production usually coincided with increased year-to-year variability and risk. Farms with larger stocking density faced more severe feed gaps and were more sensitive to climate change than less densely stocked farms. The first adaptation package resulted in increased stover production and a small increase in livestock productivity. The inclusion of grain and forage legumes with the second package increased milk productivity and net revenues more profoundly by 30%. This was attributed to the alleviation of dry-season feed gaps, which also reduced the sensitivity to climate change compared to the current system. Clearly, individual farms were affected differently by climate change and by improved farm management, illustrating that disaggregated impact assessments are needed to effectively inform decision making towards climate change adaptation.

We use an attributional life cycle assessment (LCA) and simulation modelling to assess the effect of improved feeding practices and increased yields of feed crops on milk productivity and GHG emissions from the dairy sector of Tanzania’s southern highlands region. We calculated direct non-CO2 emissions from dairy production and the CO2 emissions resulting from the demand for croplands and grasslands using a land footprint indicator. Baseline GHG emissions intensities ranged between 19.8 and 27.8 and 5.8–5.9 kg CO2eq kg−1 fat and protein corrected milk for the Traditional (local cattle) and Modern (improved cattle) sectors. Land use change contributed 45.8–65.8% of the total carbon footprint of dairy. Better feeding increased milk yields by up to 60.1% and reduced emissions intensities by up to 52.4 and 38.0% for the Traditional and Modern sectors, respectively. Avoided land use change was the predominant cause of reductions in GHG emissions under all the scenarios. Reducing yield gaps of concentrate feed crops lowered emissions further by 11.4–34.9% despite increasing N2O and CO2 emissions from soils management and input use. This study demonstrates that feed intensification has potential to increase LUC emissions from dairy production, but that fertilizer-dependent yield gains can offset this increase in emissions through avoided emissions from land use change.

Evaluation of lifetime productivity of individual animals in response to various interventions allows assessment of long-term investment opportunities for farmers. In order to gain a better understanding of promising feed interventions for improvement of small ruminant production in Southwestern Nigeria, a dynamic modelling approach was used to explore the effect of different feeding strategies on the lifetime productivity of West African Dwarf (WAD) goats. Modifications were made to the current version of Livestock Simulator developed for cattle production to simulate goat production systems particularly for WAD goats. Effects of changes in input parameters (quality of feed and potential adult weight) confirmed the sensitivity of the modelled weight development and reproductive performance. The values of simulated model outputs corresponded well with observed values for most of the variables, except for the pre-weaning mortality rate in the cut-and-carry system where a wide discrepancy between simulated (2.1%) and observed (23%) data was found. The scenario analysis showed that simulated goats in the free grazing system attained sexual maturity and kidded much later than those in the grazing with supplementation and the cut-and-carry systems. The simulated results suggested that goats require supplementation with protein and energy sources, in order to promote lifetime productivity, early sexual maturity and higher birth weight. In terms of economic returns based on feed cost alone, the moderately intense system produced the most profit. We therefore conclude that grazing with adequate supplementation using farm-generated feed resources offers an opportunity for improving smallholder goat production systems in West Africa.