The Availability of Non-Timber Forest Products under Forest Succession on Abandoned Fields along the Wild Coast, South Africa

Responses of soil fungal communities and functional guilds to ~160 years of natural revegetation in the Loess Plateau of China

Natural revegetation has been widely confirmed to be an effective strategy for the restoration of degraded lands, particularly in terms of rehabilitating ecosystem productivity and soil nutrients. Yet the mechanisms of how natural revegetation influences the variabilities and drivers of soil residing fungal communities, and its downstream effects on ecosystem nutrient cycling are not well understood. For this study, we investigated changes in soil fungal communities along with ~160 years of natural revegetation in the Loess Plateau of China, employing Illumina MiSeq DNA sequencing analyses. Our results revealed that the soil fungal abundance was greatly enhanced during the later stages of revegetation. As revegetation progresses, soil fungal richness appeared first to rise and then decline at the climax Quercus liaotungensis forest stage. The fungal Shannon and Simpson diversity indexes were the lowest and highest at the climax forest stage among revegetation stages, respectively. Principal component analysis, Bray–Curtis similarity indices, and FUNGuild function prediction suggested that the composition, trophic modes, and functional groups for soil fungal communities gradually shifted along with natural revegetation. Specifically, the relative abundances of Basidiomycota, Agaricomycetes, Eurotiomycetes, and ectomycorrhizal fungi progressively increased, while that of Ascomycota, Sordariomycetes, Dothideomycetes, Tremellomycetes, saprotrophic, pathotrophic, arbuscular mycorrhizal fungi, and endophyte fungi gradually decreased along with natural revegetation, respectively. The most enriched members of Basidiomycota (e.g., Agaricomycetes, Agaricales, Cortinariaceae, Cortinarius, Sebacinales, Sebacinaceae, Tricholomataceae, Tricholoma, Russulales, and Russulaceae) were found at the climax forest stage. As important carbon (C) sources, the most enriched symbiotic fungi (particularly ectomycorrhizal fungi containing more recalcitrant compounds) can promote organic C and nitrogen (N) accumulation in soils of climax forest. However, the most abundant of saprotrophic fungi in the early stages of revegetation decreased soil organic C and N accumulation by expediting the decomposition of soil organic matter. Our results suggest that natural revegetation can effectively restore soil fungal abundance, and modify soil fungal diversity, community composition, trophic modes, and functional groups by altering plant properties (e.g., plant species richness, diversity, evenness, litter quantity and quality), quantity and quality of soil nutrient substrates, soil moisture and pH. These changes in soil fungal communities, particularly their trophic modes and functional groups along with natural revegetation, impact the accumulation and decomposition of soil C and N and potentially affect ecosystem C and N cycling in the Loess Plateau of China.

Abandoned Croplands: Drivers and Secondary Succession Trajectories under Livestock Grazing in Communal Areas of South Africa

Cropland abandonment has been happening in different parts of the world and is being driven by socio-economic, ecological, edaphic, and environmental factors. Most of the research focusing on drivers of cropland abandonment, succession trajectories, and responses to active restoration initiatives has been conducted in the republic of Nepal and regions such as Europe and America. In South Africa, the impact of cropland abandonment on household livelihoods, changes in vegetation and soil properties, and soil seed bank statuses have been conducted mainly in the Eastern Cape Province. The drivers of cropland abandonment in South Africa are like those observed in other countries, except for a few, which are country-specific such as poor support of communal farmers compared to their counterparts in the highly mechanised commercial farming sector. There is also a shift from low input cropping in the distant fields to high input cultivation in homestead gardens. Research results elsewhere suggest a woody growth suppressive effect of grazing, particularly average grazing intensities, being crucial in suppressing woody proliferation while high grazing intensities are detrimental to herbaceous species’ richness and promote woody species’ encroachment. A combination of fire and grazing alters the natural succession trajectory by promoting fire-tolerant species and arresting woody species. Similar to other countries, cropland abandonment is associated with colonisation by alien invasive species which are favoured by cropping legacies, such as altered soil levels of pH, Nitrogen, and phosphorus. Furthermore, limited moisture in semi-arid areas promotes the encroachment of indigenous woody species. Secondary succession in abandoned croplands can be manipulated for the benefit of livestock production in communal areas by introducing management strategies that will discourage encroachment by both invasive and indigenous woody species which lowers the grazing capacity. Furthermore, active restorative practices, such as reseeding with indigenous mid succession perennial grasses and legumes, will improve forage quality in abandoned croplands. Our understanding of succession trajectories under various unique disturbance regimes experienced in South Africa, such as communal grazing of abandoned croplands, compared to situations in other parts of the world is limited. Furthermore, the influence of other factors such as fire, soil fertility, and moisture needs to be understood.

Species-landscape interactions drive divergent population trajectories in four forest-dependent Afromontane forest songbird species within a biodiversity hotspot in South Africa

Species confined to naturally fragmented habitats may exhibit intrinsic population complexity which may challenge interpretations of species response to anthropogenic landscape transformation. In South Africa, where native forests are naturally fragmented, forest-dependent birds have undergone range declines since 1992, most notably among insectivores. These insectivores appear sensitive to the quality of natural matrix habitats, and it is unknown whether transformation of the landscape matrix has disrupted gene flow in these species. We undertook a landscape genetics study of four forest-dependent insectivorous songbirds across southeast South Africa. Microsatellite data were used to conduct a priori optimization of landscape resistance surfaces (land cover, rivers and dams, and elevation) using cost-distances along least-cost pathway (LCP), and resistance distances (IBR). We detected pronounced declines in effective population sizes over the past two centuries for the endemic forest specialist Cossypha dichroa and Batis capensis, alongside recent gene flow disruption in B. capensis, C. dichroa and Pogonocichla stellata. Landscape resistance modelling showed both native forest and dense thicket configuration facilitates gene flow in P. stellata, B. capensis and C. dichroa. Facultative dispersal of P. stellata through dense thicket likely aided resilience against historic landscape transformation, whereas combined forest-thicket degradation adversely affected the forest generalist B. capensis. By contrast, Phylloscopus ruficapilla appears least reliant upon landscape features to maintain gene flow and was least impacted by anthropogenic landscape transformation. Collectively, gene flow in all four species is improved at lower elevations, along river valleys, and riparian corridors- where native forest and dense thicket better persist. Consistent outperformance of LCP over IBR land-cover models for P. stellata, B. capensis and C. dichroa demonstrates the benefits of wildlife corridors for South African forest-dependent bird conservation, to ameliorate the extinction debts from past and present anthropogenic forest exploitation.