AbstractSouth Africa is the World’s largest producers of macadamia nuts, with about 51,000 ha of land covered by macadamia. This leads to major farming challenges, as the expansion of orchards is associated with the loss of habitat and biodiversity, the excessive use of and resistance to insecticides, and an increased pressure on water resources. More frequent and severe droughts and heat waves are projected to worsen the situation and have already negatively affected harvests. Here we review current literature and recent work conducted in the subtropical fruit growing area of Levubu, South Africa, which include catchment-scale assessments of ground water, landscape-scale studies on pest control and pollination services, through to evaluations of tree-level water use. Several biological control options are being developed to replace pesticides. Results suggest that bats and birds provide large and financially measurable pest control services, and interventions should therefore focus on maintaining functional landscapes that would be resilient in the face of global climate change. This would include a landscape matrix that includes natural vegetation and minimize water consumption by optimizing irrigation schedules.

In many crops, both pollination and biocontrol determine crop yield, whereby the relative importance of the two ecosystem services can be moderated by the landscape context. However, additive and interactive effects of pollination and biocontrol in different landscape contexts are still poorly understood. We examined both ecosystem services in South African macadamia orchards. Combining observations and experiments, we disentangled their relative additive and interactive effects on crop production with variation in orchard design and landscape context (i.e., cover of natural habitat and altitude). Insect pollination increased the nut set on average by 280% (initial nut set) and 525% (final nut set), while biocontrol provided by bats and birds reduced the insect damage on average by 40%. Pollination services increased in orchards where macadamia tree rows were positioned perpendicular to orchard edges facing natural habitat. Biocontrol services decreased with elevation. Pest damage was reduced by higher cover of natural habitat at landscape scale but increased with elevation. Pollination and biocontrol are both important ecosystem services and complementary in providing high macadamia crop yield. Smart orchard design and the retention of natural habitat can simultaneously enhance both services. Conjoint management of ecosystem services can thus enable the ecological intensification of agricultural production.

Strengthening participation of Global South researchers in tropical ecology and conservation is a target of our scientific community, but strategies for fostering increased engagement are mostly directed at Global North institutions and researchers. Whereas such approaches are crucial, there are unique challenges to addressing diversity, equity and inclusion (DEI) within the Global South given its socio-economic, cultural and scientific contexts. Sustainable solutions protecting biodiversity in the tropics depend on the leadership of Global South communities, and therefore DEI improvements in the Global South are paramount in our field. Here, we propose ten key actions towards equitable international collaborations in tropical ecology, which, led by Global South researchers, may improve DEI at institutional, national and international levels. At an institutional level, we recommend (1) becoming role models for DEI, (2) co-developing research with local stakeholders, and (3) promoting transparent funding management favouring local scientists. At a national level, we encourage (4) engagement in political actions protecting scientists and their research in tropical countries, (5) participation in improving biodiversity research policies, and (6) devising research that reaches society. At an international level, we encourage Global South researchers in international collaborations to (7) lead and direct funding applications, (8) ensure equitable workloads, and (9) procure equal benefits among national and foreign collaborators. Finally, (10) we propose that Global South leadership in DEI efforts has the most potential for worldwide improvements, supporting positive long-lasting changes in our entire scientific community. Supplementary materials provide this abstract in 18 other languages spoken in the Global South.

Climate and insect pests are vital variables that affect crop production. Climate change will alter the magnitude and timing of precipitation, but how rainfall and temperature interact to affect insect pest damage in agriculture is poorly understood. Here, we explore the interacting effects of elevation and contrasting weather conditions (a wet vs. dry year) on macadamia nut quality, which is strongly affected by insect pests. For two years, we sampled macadamia nuts at 40 plots, stratified across ten farms along an elevational gradient in subtropical Limpopo province of South Africa. As measures of nut quality, we related total kernel recovery, nut immaturity, and kernel insect damage to precipitation and elevation. Higher rainfall reduced nut quality in all three response variables, while colder temperatures at higher elevations mitigated this effect. Our findings suggest that future warmer temperatures, more intense and wetter rainy seasons could lead to lowered macadamia nut quality even at higher elevations and economic losses to the industry.

More sustainable and environmentally friendly agricultural practices, including ecological intensification, are needed to reduce biodiversity loss and environmental degradation. We evaluated the potential of ecological intensification through the enhancement of pollination services in an intensively managed and insect-pollinated crop, Macadamia integrifolia. We compared the effects and importance of agronomic practices that include agronomic input (i.e. irrigation and managed honeybees), orchard design requiring no external inputs (i.e. spatial orchard structure) and landscape factors in 10 South African macadamia orchards. In comparison to experimental pollinator exclusion, insect pollination increased the initial and final nut set by 304% and 23%, respectively. However, nut set was pollination limited as hand pollination further improved nut set. Flower visitation rates increased with the cover of semi-natural habitats in the surrounding landscape (1 km radius). This effect was outperforming the effect of the number of managed honeybee colonies, as agronomic practice. Initial nut set increased with orchard design and flower visitation rates. Perpendicular orientation of the planted macadamia rows towards the semi-natural habitats increased initial nut set more than threefold compared to parallel row orientation. The initial nut set was 80% higher at the edge to semi-natural habitats than in the orchard centre. In contrast, agronomic practices, such as irrigation, did not increase initial nut set. Final nut set depended on the preconditions of the initial nut set, additionally, high altitudes and the position in the centre of the orchard had positive effects. Synthesis and applications: Pollination services were prerequisites for high yields in macadamia and could be improved without further agronomic input. Especially, the orchard design, that is, spatial arrangement of tree rows and semi-natural habitats at local and landscape scales, was more important to boost insect pollination and the initial development of macadamia nuts than agronomic practices, such as high levels of irrigation. Considering the urgency to reduce the environmental impacts of agricultural production, we highlight the high potential of ecological intensification by a smart orchard design and the restoration and conservation of semi-natural habitats in the orchards and their surrounding landscape.

Quantifying how multiple ecosystem services and functions are affected by different drivers of Global Change is challenging. Particularly in African savanna regions, highly integrated land-use activities created a landscape mosaic with flows of multiple resources between land use types. A framework is needed that quantifies the effects of climate change, management and policy interventions on ecosystem services that are most relevant for rural communities, such as provision of food, feed, carbon sequestration, nutrient cycling and natural pest control. In spite of progress made in ecosystem modelling, data availability and stakeholder interactions, these elements have neither been brought together in an integrated framework, nor evaluated in the context of real-world problems. Here, we propose and outline such framework as developed by a multi-disciplinary research network, the Southern African Limpopo Landscapes network (SALLnet). Components of the framework such as the crop model APSIM and the vegetation model aDGVM2 had already been parameterized and evaluated using data sets from savanna regions of eastern, western and southern Africa, and were fine-tuned using novel data sets from Limpopo. A prototype of an agent-based farm household model was developed using comprehensive farm survey information from the Limpopo Province of South Africa. A first test of the functionality of the integrated framework has been performed for alternative policy interventions on smallholder crop-livestock systems. We discuss the versatile applicability of the framework, with a focus on smallholder landscapes in the savanna regions of southern Africa that are considered hotspots of global change impacts.