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The study of pests and diseases on crops and crop relatives in the wild is valuable from both a theoretical and an applied point of view. Few studies have addressed multiple pests and diseases in such ecosystems. Our objectives were to (1) compare the prevalence of multiple pests and diseases on coffee in forests and more managed landscapes and (2) assess how spatial, environmental, host density and management factors affect the incidence and severity of coffee pests and diseases across forests. To achieve these objectives we studied different pests, diseases and one hyperparasite on wild and semi-wild coffee from 84 plots of 20 × 20 m across a forested landscape in southwest Ethiopia and compared the results to previous studies of more intensively managed adjacent landscapes. The prevalence of all surveyed coffee leaf pests and diseases was high (>71% of investigated plots) and very similar to the levels in more intensively managed landscapes reported in the literature. The incidence rates of all pests, diseases and the hyperparasite showed a high variation among the plots, and correlation with each other in some cases. However, this variation was weakly related to the measured environmental and management variables, but coffee pests and diseases were often positively related to high coffee density. One possible explanation for the similar prevalence is that, although the landscapes are different, the local environmental conditions have much in common since coffee is also grown under indigenous shade trees in more intensively managed landscapes. However, the variability in pest and disease levels among sites was large and it is difficult to predict where they attain high levels. There is a need of detailed investigations on drivers of spatio-temporal population dynamics of these species, including their natural enemies, to be able to provide advice for development of sustainable coffee disease management. [ABSTRACT FROM AUTHOR]

Plants, including those managed by humans, are often attacked by multiple diseases. Yet, most studies focus on single diseases, even if the disease dynamics of multiple species is more interesting from a farmers' perspective. Moreover, most studies are from single management systems, although it is valuable to understand how diseases are distributed across broad management gradients, especially in cases where less intensive management also provides biodiversity values in the landscape. To understand the spatial dynamics and drivers of diseases across such a broad management gradient, we assessed four major fungal diseases on Arabica coffee (Coffea arabica) at 60 sites in southwestern Ethiopia along a gradient from only little managed wild coffee in the forest understory to intensively managed coffee plantations. We found that environmental and management factors related to disease incidence and severity differed strongly among the four fungal diseases. Coffee leaf rust (Hemileia vastatrix) and Armillaria root rot (Armillaria mellea) were more severe in intensively managed sites, whereas coffee berry disease (Colletotrichum kahawae) and wilt disease (Gibberella xylarioides) were more severe in less managed sites. Among sites, incidence and severity of the four fungal diseases poorly correlated with each other. Within sites, however, shrubs that were severely attacked by coffee leaf rust also had high levels of berry disease symptoms. A better understanding of disease dynamics is important for providing management recommendations that benefit smallholder farmers, but also to evaluate possibilities for maintaining biodiversity values in the landscape related to shade cover complexity and wild coffee genetic variation. [ABSTRACT FROM AUTHOR]

Nowadays agricultural expansion and the concurrent climate variability jointly jeopardized global biodiversity in general and plant species diversity in particular. Assessing current diversity status of different land uses is a proxy for anticipating their individualistic resilience against future climatic variability. Here we explored woody species composition, diversity, distribution, and indicator species across five agricultural land uses. For this we employed a systematic sampling design to collect phytosociological attributes of woody plant species from 103 plots in four landscapes at a regular distance following transect lines. For comparative diversity analysis, we used linear mixed effects model using the lmer function and subsequently, post hoc pairwise comparisons with the emmeans function of R software. To visualize species composition dissimilarities between the land uses, we applied NMDS ordination based on Bray-Curtis dissimilarity index and subsequently, adonis2 () function (R software) was used for testing its significance and pair-wise PERMANOVA analysis. Linear regression model and multiple regression model by Envfit function was used to test the effect of environmental topographic variables on the species distribution. The result indicated that, 104 woody plant species belonging to 52 families were collected, in which significant differences in species richness and composition among the five land use types were showed. The result reveal that, forest is with the most diversified species assemblage followed by home gardens. However, grazing land is the least in species diversity. Among topographic variables, elevation gradient shows significant influence on diversity and species compositional dissimilarity among the five agricultural land uses in which 38 species were significantly contributed to the dissimilarity of species composition. Species richness and woody stem abundance declines with increasing elevation. However, slope and aspect does not show significant effect on these attributes analysis. Indicator species assessment (IndVal.) showed that, 20 species were significantly (P ≤ 0.001) associated with at least one of the five land use classes in agricultural landscape. In sum, this study highlights that, changes in woody species diversity, composition and spatial patterns are the responses to types of land uses of varying disturbance intensities and topographic elevation as a proxy to different environmental factors. [ABSTRACT FROM AUTHOR]

Biological control by predators of insect pests is an important benefit of biodiversity, having a contribution to agricultural production. By preying on crop infesting insect pests, predatory arthropods and birds can provide an important ecosystem service. They support agricultural productivity, boosting crop yield and reducing demand for pesticides expense. Habitat quality of land use types, i.e., explained by vegetation cover, can impact the provision of ecosystem services thereby influencing the prevalence of the predators and their predation rates. In order to better understand the level of insect pest control service by predators, we conducted a field experiment to investigate levels of predation, using an attack on artificial caterpillars in response to land use types varied in vegetation cover. We found the attack rate by arthropods was more consistent across land use types than by birds, and the attack by birds was higher in modified land use types with sparse woody vegetation. Moreover, the attack rate for birds showed a decreasing tendency with increasing woody species richness, cover and stem density, while it showed less variation for arthropods. We conclude that biological control by birds is more effective in habitats with simplified vegetation cover than for arthropods in agricultural landscapes. Therefore, we recommend the prevalence of shade trees and small forest patches in agricultural landscapes for supporting the increased levels of insect pest control services provided by predatory birds and arthropods. • Woody vegetation provides habitat for predatory birds and arthropods. • The quality of woody cover may vary depending on the type of land use. • Crop pest insects are the main causes of reductions in crops productivity. • Predatory arthropods and birds can remove pest through biological control. • Predation rates of arthropods and birds may vary depending on woody cover. [ABSTRACT FROM AUTHOR]

Abstract: The composition of coffee shade tree species and density of arbuscular mycorrhizal fungi (AMF) spores in Bonga natural coffee forest of southwestern Ethiopia were investigated. This study is the first report on AMF populations of Ethiopian natural coffee forests. The main purposes were to systematically identify the dominant coffee shade tree species, evaluate their densities and quantify and characterize populations of arbuscular mycorrhizal fungi particularly in the rhizosphere of coffee plants. Sample plots of 400m2 with coffee plants and dominant shade tree species were selected. Sampling of soil was carried out at a depth of 0–15cm from the rooting areas of shaded and unshaded coffee plants for analysis of some soil parameters and quantification of AMF spores. Nineteen dominant shade tree species belonging to 14 plant families were identified in considered 10 quadrates. In terms of their stand dominance, Millettia ferruginea (Hochst.) Baker had the highest frequency of occurrence (22.3%) followed by O. welwitschii Friis & P.S. Green (15.5%). High density (503stems/ha) and/or percentage (66%) of Coffea arabica L. were recorded. All soil samples yielded AMF spores and the counts ranged from 4 to 67 spores 100g−1 of dry soil. Notably higher mean counts of AMF spores were found under leguminous shade trees compared to non-leguminous ones. AMF spore counts were significantly positively correlated with coffee counts and available soil P content. Five genera of AMF were identified based on spore morphology. Glomus dominated members of Glomeromycota. The other genera found were Gigaspora, Acaulospora, Entrophospora and Scutellospora in order of occurrence. The present investigation has documented species richness among dominant coffee shade tree species along with a fair distribution of relevant numbers and types (genera) of AMF to stimulate coffee growth. Thus, Bonga natural coffee forest seems to be an ideal focal forest for in situ coffee genetic resources conservation and promotion of organic coffee production. [Copyright &y& Elsevier]

A recent trend in conservation biology is not only to focus on protected areas of natural vegetation but also on the management of agricultural landscapes, since these landscapes are considered to be of vital importance for overall landscape biodiversity − both through the opportunity for species to thrive there and as conduits for inter-patch dispersal. Since trees are considered to be key structures to enhance biodiversity in agricultural landscapes, we need to understand what factors regulate their occurrences. Farmers choices will decide the composition of land-uses and the associated densities and composition of trees. We compared tree density and tree species composition across eight different land use types replicated in ten agricultural landscapes in relatively humid climates of mid-altitudes (1500–2500 m asl) in Ethiopia. In each landscape five transects of 1 km divided into 50 plots of 20 × 20 m were surveyed for woody plants. Annual crop plots had a low tree density (of trees >10 cm DBH) (6 per ha), but since it generally was the most abundant land use type altogether, many tree species were still found there (4–29 per transect in the different landscapes). Most tree species had their highest relative occurrence in the perenial crops land-use type and among the different perenial crop types, plots with coffee were more species rich than plots with khat ( Catha edulis ) (a stimulant crop increasing in frequency); plots with Eucalyptus trees were intermediate. A few species were more associated with grazing areas and homegardens indicating that a combination of land-uses enhances the overall species diversity in these agricultural landscapes. However, if the trend of increasing areas of khat and Eucalyptus would lead to decreases in shade coffee there is a risk for severe erosion of tree density and species richness across these landscapes with cascading effects on associated biodiversity. [ABSTRACT FROM AUTHOR]

The Sanetti Plateau is Africa's largest Afro-alpine ecosystem. As part of an ongoing effort to reconstruct the paleo-extent of Ericaceous vegetation in this ecosystem, we aim to identify unambiguous Erica biomarkers. Here, we present a respective study focusing on plant-derived terpenoids. Terpenoids from seven keystone plant species were identified and quantified using gas chromatography-mass spectrometry (GC-MS). Widely employed angiosperm biomarkers such as lupane, oleanane, ursane, and taraxastane-type triterpenoid alcohols, acids, and esters were detected with a more ample presence in Erica species and Lobelia rhynchopetalum. Ursolic acid is always the predominant triterpenoid, followed by oleanolic acid. The beta- and alpha-amyrin triterpenoids allowed distinguishing Erica trimera from the other plants in hierarchical cluster analysis (HCA). The nearly exclusive presence of amyrin acetate in particular and the total terpenoid content in Erica species corroborate the potential of terpenoid biomarkers for reconstructing the paleo-extent of Ericaceous vegetation in the soil and sediments. Moreover, 3beta-taraxerol may serve as a proxy to distinguish the morphologically and ecologically very similar Erica trimera and Erica arborea. Given that the diagenetic alteration of taraxerol as well as other terpenoid biomarkers should not be overlooked, ongoing research is needed and encouraged to address this issue. • Lupane, oleanane, ursane, and taraxastane-type triterpenoids were detected with a more ample presence in Erica species and Lobelia rhynchopetalum. • Ursolic acid is always the predominant triterpenoid, followed by oleanolic acid. • The β- and α-amyrin triterpenoids allowed distinguishing E. trimera from the other plants in hierarchical cluster analysis (HCA). [ABSTRACT FROM AUTHOR]

Abstract: The ericaceous vegetation zone of the unique and highly fragmented afro-alpine environment in the eastern African high mountains is typically dominated by the heather Erica arborea, often in combination with its close relative E. trimera. Both species are shrubs or small trees with tiny seeds, potentially capable of dispersal by wind over long distances. While E. arborea is widely distributed in Africa, the Middle East and Europe, E. trimera is endemic to the afro-alpine region where it is restricted to higher altitudes than E. arborea. We used Amplified Fragment Length Polymorphisms (AFLPs) and variation in non-coding plastid DNA sequences to test whether these two morphologically and ecologically very similar species display similar phylogeographic patterns in the afro-alpine region. We predict that the more high-altitudinal E. trimera shows more distinct genetic structuring than E. arborea, because dispersal of the latter may have been facilitated by formation of interglacial forest bridges between mountains. Based on extensive field sampling in most of the high mountains of Ethiopia and East Africa, we show that the two species are clearly distinct at AFLP and plastid DNA loci. Both showed low levels of overall AFLP diversity, suggesting bottlenecking in small refugial populations during unfavourable climatic periods. However, their genetic structuring and inferred phylogeographic histories were conspicuously different. The more high-altitudinal E. trimera consisted of three to four distinct AFLP groups, which also had different plastid DNA haplotypes and different geographic distributions, suggesting long-term restriction to several refugia (at least one in Ethiopia and two in East Africa). In contrast, E. arborea showed little geographic structuring at AFLP loci and only a single, widespread plastid DNA haplotype, which may suggest recent colonization of the entire study area from a single source population, likely via a combination of gradual expansion via forest bridges and long-distance dispersals. The source population of E. arborea may be situated in (or north of) Ethiopia, which harbours most genetic diversity. [Copyright &y& Elsevier]

The multifunctional role of shade trees for conservation of biodiversity and ecosystem services in natural forests and agroforests is well documented, yet we lack insights into the impact of shade tree species identity on pest and disease dynamics on agroforestry crops such as coffee and cacao, and its implications for management. We conducted two surveys on the impact of shade tree species identity and canopy cover on pests, diseases and a fungal hyperparasite on Arabica coffee in southwestern Ethiopia, which is one of the areas of origin of Arabica coffee. One survey was in a commercial plantation, and the other along a management gradient from only little managed coffee growing in the natural forest to intensively managed commercial plantations. To link these findings to current shade tree selection criteria, we complemented these surveys by interviews with farmers and managers. Shade tree species identity left a weak imprint on insect pest levels, and insect pests levels differed strongly in the strength and direction of their response to canopy cover. In contrast to the insect pests, the incidence of coffee leaf rust and its hyperparasite, as well as coffee berry disease, differed among shade tree species, with particularly high levels of coffee leaf rust and the hyperparasite underneath the canopy of the shade trees Acacia abyssinica and Croton macrostachyus , and coffee berry disease underneath the canopy of Acacia abyssinica and Polyscias fulva. Smallholder farmers used many criteria for selecting shade trees, such as leaf traits and competition for soil moisture, but low priority is given to the effect of shade tree species identity on pests and diseases. Our findings help to understand spatial variation in pest and disease dynamics in natural forests and agroforests, and may inform the selection of shade tree species by coffee producers and thereby contribute to ecologically-informed pest and disease management. Importantly, our finding highlight the potential for using tree identity for the sustainable management of pests and diseases, with relevance for global agroforestry systems. • Tree identity left a weak imprint on insect pests, whereas it strongly affected coffee diseases. • Insect pests were strongly affected by canopy cover, but in a species-specific way. • Smallholder farmers give low priority to the effect of shade tree identity on pests and diseases. • Tree identity is important to design sustainable pest and disease management. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of how spatial variation across landscapes regulates local abundances and species richness also needs to consider possible temporal changes in such relationships. In many tropical areas, the contrast between dry and rainy season is pronounced and the types and distributions of the main floral resources differ (herbs vs trees). This shift in resources could result in different pollinator abundances, species richness and trait compositions between seasons, as well as in how these components are spatially distributed. We compared the bee species composition between dry and rainy season in an agricultural mosaic landscape in southwestern Ethiopia, and analyzed it in relation to forest cover. We sampled bees for 67 days in the dry season and 86 days in the rainy season with pan and vane traps in 28 homegardens covering a gradient from low to high tree cover in the surrounding area. We found a clear shift in species composition between seasons, with more small bee species and more below-ground nesting bees in the rainy season compared to the dry season. The distribution of height at which the bees were foraging shifted between seasons with a higher proportion of the bees foraging at tree level in the dry season. Bee abundance and richness were generally positively affected by higher forest cover surrounding the homegardens, but there were no clear interaction effects between seasons, in contrast to our hypothesis. The clear turnover in species composition between seasons and the positive effect of forest cover show that mechanisms acting both at spatial and temporal scales are important in regulating local bee communities. [ABSTRACT FROM AUTHOR]

• Local and landscape processes drive woody plant regeneration in coffee agroforestry. • Regeneration decreased with higher local management intensity. • Seedling species richness and diversity declined with distance to intact forest. • Microclimate and seed dispersal are potential mechanisms behind these patterns. • Conservation approaches require both a local and landscape perspective. With the current deforestation rates in tropical ecosystems, optimizing biodiversity in managed systems has become fundamental for conservation. Agroforestry has been suggested to conserve biodiversity and buffer deforestation rates, while also sustaining local livelihoods. While many studies have focused on the relation between local management intensity and biodiversity, processes at the landscape scale are often overlooked and remain a knowledge gap. In this study we identified drivers behind woody plant regeneration in coffee agroforestry on both local and landscape scale. We used univariate-, multivariate- and structural equation models to relate seedling species richness, diversity, density, community composition and height to local management intensity and location in the landscape of 60 coffee agroforestry sites in southwestern Ethiopia. Local management intensity, which simplifies and reduces canopy cover, negatively impacted species richness, diversity and density, presumably due to altered microclimatic conditions and a reduction in local seed sources. Seedling height was also reduced by management intensity, including slashing frequency and canopy cover. On the landscape scale, species richness and diversity of seedlings was higher at sites adjacent to continuous forests where seed sources are abundant, and declined with distance to the forest. In particular, late successional species were negatively affected, whereas common shade tree species and pioneers occurred as seedlings throughout the landscape and in more managed systems. This suggests that dispersal limitation is detrimental for the regeneration of late successional species, especially in agroforestry systems where the standing woody plant diversity is largely reduced. Our results indicate that natural regeneration of woody plants still occurs in coffee agroforestry systems, primarily when the canopy structure is dense and diverse and/or when sites are located nearby continuous forests. Management intensification and deforestation will limit the potential for many woody plant species to regenerate in coffee agroforestry sites, by altering the local microclimate, reducing local seed sources and disrupting seed dispersal from the surrounding landscape. This will likely result in a positive feedback loop, as a reduction in woody plant regeneration reduces future seed sources. We therefore stress that both a local and a landscape perspective should be incorporated in conservation and restoration approaches. [ABSTRACT FROM AUTHOR]

• Agroecosystems provide habitats where pests and their natural enemies interact. • Coffee leaf rust and its hyperparasite had contrasting seasonal dynamics. • The hyperparasite had a potential top-down effect on rust growth rate. • The rust and hyperparasite were common at opposite ends of a management gradient. • Shade improvement can provide moist microclimate and enhance natural pest control. Agroforestry systems can provide habitats for a rich biodiversity including multitrophic interactions, which presents opportunities to develop natural pest control. Shade coffee systems in several coffee growing areas of the world host such unique habitats where pests and their natural enemies interact. One of the major global challenges for coffee production, coffee leaf rust caused by the fungal pathogen Hemileia vastatrix is attacked by the fungal hyperparasite, Lecanicillium lecanii. However, we lack insights in the dynamics and biocontrol potential of the hyperparasite on coffee leaf rust from landscapes in Arabica coffee's native range. To understand the temporal dynamics across landscapes and environmental drivers of the rust and hyperparasite, and the potential for biocontrol of the rust by the hyperparasite, we studied the rust and hyperparasite during the dry and wet seasons for three consecutive years at 60 sites across a gradient of coffee management in southwestern Ethiopia. We found that coffee leaf rust was more severe during the dry season, whereas the hyperparasite was more severe during the wet season in two out of three years. The rust growth rate from the wet to the dry season transition was negatively related to the hyperparasite index during the wet season, implying a potential top-down control. Coffee leaf rust was generally more severe at lower altitudes in the dry season, whereas the hyperparasite was more severe at high altitude. The rust incidence increased with management intensity, while the hyperparasite was more common under less intensive management. This study could be interesting in that it represents a landscape where Arabica coffee originated and the rust and hyperparasite might have a long co-evolutionary history. Our findings highlight the potential of the hyperparasite to suppress the rust's growth rate from the wet to dry season transition when the rust severity could otherwise be at its peak. We show that less intensively managed landscapes with dense shade levels are likely to increase hyperparasite abundance and result in an improved top-down control of the rust. However, more detailed knowledge is needed on the interaction of these species to assess its importance for reducing rust induced yield losses or the risk of rust outbreaks. [ABSTRACT FROM AUTHOR]