Insights from 40 years of research on mycorrhiza – walnut tree root interactions

Picture copyright Mortier et al.

Walnut trees strongly depend on arbuscular mycorrhizae for their mineral nutrition. In return, these fungi obtain from the trees, sugars and lipids to sustain their growth and reproduction. Scientists Mortier et al. surveyed 40 years of scientific literature on the relationships between arbuscular mycorrhizae and walnut tree roots. The root colonization process leads to enhanced seedling survival and quality. The knowledge of positive and negative feedbacks between walnut planting and the fungi allows developing sustainable walnut agroforestry systems.

The effect of shade trees on robusta coffee depends on tree age

Picture copyright Piato et al.

Coffee plantation productivity is threatened by both climate change and decreasing revenues of growers. Scientists Piato et al. analyzed how growing robusta coffee under shade trees impacts coffee growth, yield, and quality. They found that the effects depend on tree age and the robusta clone tested. Whereas moderate shade can increase growth and yield, excessive shade may alter cup quality.

Assessing agroforestry interventions in Northwest Vietnam

Picture copyright Do et al.

Agroforestry can reduce poverty and improve food security while addressing land degradation and delivering ecosystem services. Agroforestry systems, however, are highly complex rendering their long-term performance difficult to anticipate. Do et al. assessed several agroforestry options in the highlands of Northwest Vietnam, using decision analysis and probabilistic modeling. They calculated the benefits of these agroforestry systems but forecast important uncertainties in the decision-making process.

Winning through agroforestry

Picture copyright Kuyah et al.

Planting more trees in the landscape is a spreading strategy to provide multiple ecosystem services in human-dominated environments. Scientists Kuyah et al. recently found in sub-Saharan Africa that agroforestry practices increase provisioning services such as crop yield while maintaining the delivery of regulating and maintenance services such as soil fertility, erosion or water regulation. They reckoned that selecting appropriate agroforestry practices and a suitable management of tree canopies can minimize trade-offs resulting from competition and shading.

Assessing agroforestry resilience to climate change in West Africa

Picture copyright Gnonlonfoun et al.

Data is lacking on vulnerability and resilience of different agroforestry systems to climate change. Scientists Gnonlonfoun et al. documented these scientific gaps in West Africa through farmers’ perception. They identified several factors contributing to the resilience of ecological systems. Their knowledge is the first step for designing adaptation strategies in cooperation with local actors.

Increasing the number of trees planted on farms

Picture copyright: R. Burnett, supplied by A. Lyons

There is a general lack of tree planting in agricultural landscapes, although it improves environmental and economic performances of farms. Scientists Fleming et al. found three groups of values driving perceptions and behaviors relating to agroforestry. They reckon that farmer could increase tree planting via government incentives, mentoring, networks and support, especially when it is designed to match farmers objectives.

Cacao agroforestry yields similar income as monoculture

Picture copyright Armengot et al.

Tropical forests are dramatically decreasing. Management practices have also intensified, thus threatening biodiversity. A potential solution is agroforestry, that is the cultivation of shade trees within crops. Scientists Armengot et al. compared agroforestry and classical monoculture. They found that cacao yields were, on average, 41% higher in monocultures, but the revenues derived from agroforestry by-crops economically overcompensated for this difference.

What makes good coffee production?

Picture copyright BOREUX et al.

Coffee planters use diverse strategies to enhance coffee production, such as pruning, fertilising, removing weeds, applying lime to adjust the soil pH, irrigating coffee trees to trigger timely flowering, and removing shade trees that shade coffee plants. Agronomists Boreux et al. studied the factors of coffee production in the agroforestry system of Kodagu, India.

Trees to protect food crops against climate change

Picture copyright NASIELSKI et al.
Picture copyright NASIELSKI et al.

Agroforestry is a land use management system in which trees are grown around or among crops or pastureland. The presence of trees brings many benefits such as higher biodiversity, restoring soil fertility, cleaner water through reduced soil and fertiliser runoff and increased crop stability. A study of Nasielski et al. on soybean agroforestry suggests that yields in the tree-crop competitive zone will not be reduced under drier climate.

Innovative Swiss agroforestry

Conventional monoculture systems are failing in the long run because they have been designed solely for higher yields and economic benefits, thus neglecting pollution, biodiversity loss and non-traded social benefits. Agroforestry appears as a solution. However, farmers are often reluctant to adopt tree-based systems despite incentives to do so. To understand why, Sereke et al. have studied agroforestry in Switzerland using collaborative research and bioeconomic assessment of farmer agroforestry innovations.