Genotype–environment interaction in Gliricidia sepium: Phenotypic stability of provenances for leaf biomass yield

Limited multi-location testing has been undertaken in Gliricidia sepium and other agroforestry species compared to field crops and plantation forest tree species. Consequently, information on the stability of the various provenances (accessions) of this species is very limited, reducing the efficiency of germplasm deployment. In this study, genotype–environment interaction and phenotypic stability of 14 accessions were investigated for dry matter (DM) leaf biomass yield across five diverse sites in the tropics (Indonesia and Nigeria) and subtropics (Australia, Malawi and Zambia) using nonparametric methods. Results indicated that genotype–environment interaction is present and that some accessions were unstable across these diverse environments implying that blanket recommendation for germplasm deployment may not be efficient. The most unstable accessions for leaf biomass production in this study include the widely used Retalhuleu provenance, which although highly productive, appeared to be better suited to tropical wetter environments. The Belen Rivas and Monterrico provenances were found to combine high phenotypic stability and high DM leaf biomass yield across these diverse sites. Germplasm of these seed sources may be deployed in previously untested sites with perhaps, predictable DM leaf yields. Where further breeding and selection is envisaged, the results of this study could also be used to make selections and constitute breeding populations for either specific environments (Retalhuleu) or for diverse environments (Belen Rivas and Monterrico).

Addressing imported deforestation and zero deforestation commitments

Over a quarter of deforestation (27 percent) is caused by land use change attributed to the production of commodities (Curtis et al. 2018). Estimates of tropical forest lost attributed to expanding cropland, pastures and forest plantations range from between 62 to 80 percent (Pendrill et al. 2019, Hosonuma et al. 2012) with 26 percent of tropical forest loss attributed to the international demand for commodities (Pendrill et al. 2019). Deforestation has thus been seen as a worldwide responsibility, since products linked to deforestation in a specific location are sold and consumed worldwide. It has been estimated that 10 percent of deforestation is linked to the consumption of unsustainably sourced commodities within member countries of the EU, caused by imported commodities since deforestation within Europe is negligible (Cuypers et al. 2013). This phenomenon results in what is currently known as forest-risk commodities and commodity-driven deforestation. Commodities associated with imported deforestation produced in Central Africa are palm oil, cocoa, coffee, natural rubber, timber and cotton.

Soil Degradation Due to Conversion from Natural to Plantation Forests in Indonesia

Soil organic matter (SOM) is a crucial component of soil, through which physical, chemical, and biological characteristics interact in a local context. Within the forest category, the conversion of natural forests to monoculture plantations has raised concerns in Indonesia over the loss of soil functions, similar to conversion to agriculture. In natural forests, SOM can accumulate as part of a closed nutrient cycle with minimal nutrient losses; in plantation forestry, SOM decline and recovery can alternate over time, associated with larger nutrient losses. We reviewed existing studies to quantify how shifts from natural forests to short-rotation plantation forests (SRPF) affect SOM dynamics, soil nutrient contents, and soil-borne pathogens that cause disease. The review combines descriptive and quantitative methods (meta-analysis). The results show that conversion affects the soil C balance, soil structure and water balance, soil nutrient balance, and soil-borne diseases. Contributing factors include the reduced diversity of plant and rhizosphere communities, lower annual litter production, more uniform litter quality, and nutrient removal at the harvest cycle. Conversion from natural to plantation forest conditions also increases plant disease incidence by changing biological control mechanisms.

Biomass and soil carbon stocks in different forest types, Northwestern Ethiopia

Attempts to mitigate global climate change have brought forestry into focus. Forests absorb carbondioxide from the atmosphere, alleviate global warming and contribute for rural livelihoods. To realize these benefits, there is a need to conserve the existing forests and establish new forests by using different restoration techniques. Information is scarce in Ethiopia on the carbon stock efficiency of the different forest types. Therefore, this study focused on comparing biomass and soil carbon stock potential of a natural forest, exclosure and Eucalyptus plantation. Primary and secondary data were collected and analysed using allometric equations. The results of this study stated that the total mean carbon stock for exclosure was 131.6 ± 45.5 t ha−1, for plantation 160.1 ± 35.8 t ha−1 and for natural forest 195.3 ± 58.3 t ha−1. The carbon stocks in each pool exhibited distinct patterns between the forest types. The above ground, below ground and soil organic carbon stock, increased in the natural forests and plantation, while the litter carbon stock showed decreasing towards the exclosure. Generally, the total natural forests store high amount of carbon and can play an important role in climate change mitigation. The carbon pool variation between different forest types was significant at (P < .05); however, there was no significance difference between forest types by aboveground and belowground biomass. From the main findings of this study, it is possible to conclude that climate change mitigation measures should consider expanding exclosure with the same priority as conserving natural forest and increasing plantation forests.

Determinants of swidden communities’ land-use decision-making for different crops in Son La and Nghe An provinces, Vietnam

Conflicts of interest between forest conservation and livelihoods of swidden communities in Vietnam have been widely recognized by policy makers and scholars. However, policies and solutions to date have been based on a limited understanding of land use decisions and factors influencing these changes and strategies. This study addresses this gap by analyzing factors affecting farmers’ land use decision-making in three swidden communities in Nghe An and Son La provinces, Vietnam. Our findings show that swidden communities’ land use strategies were built on the cultural, social and economic statuses of households in response to government policies on the restriction of swidden farming, promotion of industrial forest plantations, and changes in environmental and market conditions. Our findings suggest that future policy interventions are unlikely to overcome existing conflicts between conservation and development without considering macro policies, continuous environmental and social changes, and diverse household characteristics and interests.

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