Farmer preference for macadamia varieties and constraints to production in Malawi.

Macadamia nuts constitute a vital component of both nutrition and livelihoods for smallholder producers in Malawi. We conducted a comprehensive mixed-methods study, combining qualitative and quantitative analyses, to explore varietal preferences and production challenges among these farmers. Leveraging cross-sectional data from 144 members of the Highlands Macadamia Cooperative Union Limited, our study underscores several significant findings. Our findings reveal that the majority of smallholder macadamia farmers (62%) are aged over 50, with farming as their primary occupation. Varied preferences are driven by yield-related traits, including high yield potential (38%), nut quality (29%), and extended flowering patterns (15%). Among the macadamia varieties, the top five choices, grown by over half of the farmers, include HAES 660 (18%), 800 (10%), 791 (9%), 816 (8%), and 246 (7%). Additionally, our study identifies five primary constraints faced by smallholder macadamia farmers: insect pests (81%), diseases (34%), limited market access (33%), wind damage (25%), and inadequate agricultural advisory services (17%). Based on these findings, we propose two policy recommendations to enhance smallholder macadamia production and productivity in Malawi and other regions. Specifically, we advocate for informed breeding programs that align with farmer preferences to promote greater adoption of macadamia varieties. Additionally, we emphasize the crucial role of the Malawian government in the macadamia value chain, suggesting active participation in providing extension services and marketing support, akin to its support for other cash crops.

Experimental investigation of the origin of fynbos plant community structure after fire.

BACKGROUND AND AIMS: Species in plant communities segregate along fine-scale hydrological gradients. Although this phenomenon is not unique to fynbos, this community regenerates after fire and therefore provides an opportunity to study the ecological genesis of hydrological niche segregation. METHODS: Following wildfires at two field sites where we had previously mapped the vegetation and monitored the hydrology, seeds were moved experimentally in >2500 intact soil cores up and down soil-moisture gradients to test the hypothesis that hydrological niche segregation is established during the seedling phase of the life cycle. Seedling numbers and growth were then monitored and they were identified using DNA bar-coding, the first use of this technology for an experiment of this kind. KEY RESULTS: At the site where niche segregation among Restionaceae had previously been found, the size of seedlings was significantly greater, the wetter the location into which they were moved, regardless of the soil moisture status of their location of origin, or of the species. Seedling weight was also significantly greater in a competition treatment where the roots of other species were excluded. No such effects were detected at the control site where niche segregation among Restionaceae was previously found to be absent. CONCLUSIONS: The finding that seedling growth on hydrological gradients in the field is affected by soil moisture status and by root competition shows that hydrological niche segregation could potentially originate in the seedling stage. The methodology, applied at a larger scale and followed-through for a longer period, could be used to determine whether species are differently affected by soil moisture.

A fundamental, eco-hydrological basis for niche segregation in plant communities.

• Ecologists still puzzle over how plant species manage to coexist with one another while competing for the same essential resources. The classic answer for animal communities is that species occupy different niches, but how plants do this is more difficult to determine. We previously found niche segregation along fine-scale hydrological gradients in European wet meadows and proposed that the mechanism might be a general one, especially in communities that experience seasonal saturation. • We quantified the hydrological niches of 96 species from eight fynbos communities in the biodiversity hotspot of the Cape Floristic Region, South Africa and 99 species from 18 lowland wet meadow communities in the UK. Niche overlap was computed for all combinations of species. • Despite the extreme functional and phylogenetic differences between the fynbos and wet meadow communities, an identical trade-off (i.e. specialization of species towards tolerance of aeration and/or drying stress) was found to cause segregation along fine-scale hydrological gradients. • This study not only confirms the predicted generality of hydrological niche segregation, but also emphasizes its importance for structuring plant communities. Eco-hydrological niche segregation will have implications for conservation in habitats that face changing hydrology caused by water abstraction and climate change.