Agroforestry Management Research Articles

Multifunctional shade-tree management in tropical agroforestry landscapes - a review

Summary 1. Agricultural intensification reduces ecological resilience of land-use systems, whereas paradoxically, environmental change and climate extremes require a higher response capacity than ever. Adaptation strategies to environmental change include maintenance of shade trees in tropical agroforestry, but conversion of shaded to unshaded systems is common practice to increase short-term yield. 2. In this paper, we review the short-term and long-term ecological benefits of shade trees in coffee Coffea arabica, C. canephora and cacao Theobroma cacao agroforestry and emphasize the poorly understood, multifunctional role of shade trees for farmers and conservation alike. 3. Both coffee and cacao are tropical understorey plants. Shade trees in agroforestry enhance functional biodiversity, carbon sequestration, soil fertility, drought resistance as well as weed and biological pest control. However, shade is needed for young cacao trees only and is less important in older cacao plantations. This changing response to shade regime with cacao plantation age often results in a transient role for shade and associated biodiversity in agroforestry. 4. Abandonment of old, unshaded cacao in favour of planting young cacao in new, thinned forest sites can be named ‘short-term cacao boom-and-bust cycle’, which counteracts tropical forest conservation. In a ‘long-term cacao boom-and-bust cycle’, cacao boom can be followed by cacao bust due to unmanageable pest and pathogen levels (e.g. in Brazil and Malaysia). Higher pest densities can result from physiological stress in unshaded cacao and from the larger cacao area planted. Risk-averse farmers avoid long-term vulnerability of their agroforestry systems by keeping shade as an insurance against insect pest outbreaks, whereas yield-maximizing farmers reduce shade and aim at short-term monetary benefits. 5. Synthesis and applications. Sustainable agroforestry management needs to conserve or create a diverse layer of multi-purpose shade trees that can be pruned rather than removed when crops mature. Incentives from payment-for-ecosystem services and certification schemes encourage farmers to keep high to medium shade tree cover. Reducing pesticide spraying protects functional

A strategy for tree-perennial crop productivity: nursery phase nutrient additions in cocoa-shade agroforestry systems

Shade tolerant species response to nutrient additions and light regulation by canopy trees in perennial agroforestry systems has been well documented. However, accelerated early growth, particularly in cocoa-shade systems, may be offset by competition for limited resources on nutrient poor sites. To date, few agroforestry management strategies focus on nutrient manipulation of the shade tree component or strategies for precision nutrient application. Our research objective was to diagnose interactions between nutrient supplied shade trees intercropped with cocoa. We established greenhouse trials in Kwadaso, Ghana cultivating Terminalia superba seedlings with four fertility treatment levels: conventional rate (current practices) under linear additions, and half, full and double conventional rate under exponential additions (steady-state nutrition) to determine maximal growth and nutrient uptake. After 4 months of additions in the nursery, pre-fertilized T. superba seedlings were then out-planted into field trials with cocoa seedlings. After 4 months of intercropping, cocoa associated with half rate exponentially supplied T. superba had significantly larger leaf area, greater leaf number, and higher nutrition (N and P uptake) than cocoa associated with full rate conventionally supplied T. superba. This may be attributed to (1) more favorable light conditions under these taller shade seedlings and (2) the internal use of nutrients associated with exponentially supplied T. superba seedlings, which lowered stress on native soil resources. The latter is corroborated with our findings on soil fertility status. This strategy focused on reducing fertilizer inputs and developing precise plant nutrition technology for on-farm use. Our findings suggest that shade seedlings under steady state nutrition can mitigate early growth competition in the field.

Seasonal Contrasts in the Response of Coffee Ants to Agroforestry Shade-Tree Management

In many tropical landscapes, agroforestry systems are the last forested ecosystems, providing shade, having higher humidity, mitigating potential droughts, and possessing more species than any other crop system. Here, we tested the hypothesis that higher levels of shade and associated humidity in agroforestry enhance coffee ant richness more during the dry than rainy season, comparing ant richness in 22 plots of three coffee agroforestry types in coastal Ecuador: simple-shade agroforests (intensively managed with low tree species diversity), complex-shade agroforests (extensively managed with intermediate tree species diversity) and abandoned coffee agroforests (abandoned for 10-15 yr and resembling secondary forests). Seasonality affected responses of ant richness but not composition to agroforestry management, in that most species were observed in abandoned coffee agroforests in the dry season. In the rainy season, however, most species were found in simple-shade agroforests, and complex agroforestry being intermediate. Foraging coffee ants species composition did not change differently according to agroforestry type and season. Results show that shade appears to be most important in the dry seasons, while a mosaic of different land-use types may provide adequate environmental conditions to ant species, maximizing landscape-wide richness throughout the year.

Impacts of coffee agroforestry management on tropical bee communities

Though it is undoubted that tropical bees are influenced by habitat composition, few studies have investigated the relative importance of both local and landscape-level habitat parameters in supporting large and diverse bee communities. The conservation of native bee communities within agroforestry landscapes is particularly urgent given the importance of pollination services within these systems. In this study, we examined tropical bee communities within a largely deforested shade coffee-growing region in Chiapas, Mexico. We used regression tree modeling to examine the response of bee functional groups to local and landscape-level habitat management. Our models revealed that the most predictive factors for bee abundance and species richness were the number of tree species, the number of tree species in flower, and the canopy cover of the local agroforestry landscape. Solitary bees were most abundant in habitats with high canopy cover, while social bees were most abundant in habitats with greater tree species richness. Cavity-nesting and wood-nesting bee abundance was positively affected by the amount of canopy cover in the farm, while ground-nesting bees were most abundant in habitats with a large number of tree species in flower. Our results demonstrate that across bee sociality groups, nesting guilds, and tribes, the most critical factor impacting native bee communities was within-farm local vegetation management. These results reveal the important role that agroforestry managers can have on biodiversity conservation, and the potential contribution they can make by creating resource-rich agricultural matrices. Specifically, our findings highlight the importance of diverse overstory tree management in supporting native bee communities within tropical agroforestry systems.

Relação entre macrofauna edáfica e atributos químicos do solo em diferentes agroecossistemas

O objetivo deste trabalho foi avaliar o efeito do uso do solo sobre a densidade e a diversidade da macrofauna invertebrada, bem como a relação dessa com atributos químicos do solo em diferentes agroecossistemas. Foram estudados cinco agroecossistemas: sistema ecológico com três anos de adoção (SE3), sistemas agroflorestais com seis (SAF6) e dez (SAF10) anos de adoção; agricultura de corte e queima (ACQ), e floresta nativa (FN). Em cada sistema, foram coletadas aleatoriamente cinco amostras solo, em forma de blocos (25x25 cm), na profundidade de 10 cm, nas épocas seca (outubro, 2006) e chuvosa (maio, 2007). A relação entre os atributos químicos e a macrofauna edáfica, nos diferentes sistemas de uso do solo, foi determinada por meio da análise da coinércia. Maior abundância da macrofauna foi observada na época chuvosa. Os sistemas SE3, SAF6 e SAF10 apresentaram maior riqueza de espécies e índices de Shannon e Pielou, independentemente da época de coleta. O manejo agroflorestal favoreceu a ocorrência de "engenheiros do ecossistema". Os sistemas agroflorestais propiciam melhores características químicas do solo e aumentos na abundância e riqueza da macrofauna invertebrada do solo.

Using vector analysis to understand temporal changes in understorey-tree competition in agroforestry systems

Techniques to determine the respective effects of resource limitation or over supply on tree productivity are important for developing effective forestry and agroforestry management strategies. There is a need for a simple integrative measure of the understorey effect on soil nutrient and moisture competition on tree productivity in agroforestry systems during the time period before trees dominate understorey vegetation. For the first time, the little used, but potentially valuable tool of vector analysis was evaluated over 5 years by investigating nutrient and water competition in a Pinus radiata silvopastoral experiment which had 5 pastures and a nil-understorey control. The study, from ages 2 to 6 years, was on fertile arable soils in a temperate, sub-humid climate. Establishing permanent crops on this arable site increased soil pH, C, N, organic-P and C:N ratio. Vector analysis, an analysis based on fascicle nutrient concentrations, dry weights and nutrient contents, predicted nutrient and moisture competition until the trees dominated the site after year 5. Foliar critical nutrient levels were helpful where one of the vectors was unable to distinguish between nutrient and moisture stresses. While moisture and N were found to be the main competitive factors, vector analysis also detected foliar nutrient accumulation, particularly for P and Mg. Lucerne and phalaris understoreys were the most competitive pastures, followed by cocksfoot and the two ryegrass treatments. Foliage vector analysis enabled the relative competitive effects of soil nutrients and moisture on tree productivity to be determined. Soil nutrient concentrations and soil moisture measurements and the effects of competition on tree growth were consistent with predictions from vector analysis.

Growth of Trees Planted for Rehabilitation of a Saline Area of the Wheatbelt in Western Australia

We clarified the relationship between environmental factors and the growth of seven Eucalyptus species and Casuarina obesa planted at an afforestation site in southern Western Australia's wheatbelt. The site consisted of abandoned fields damaged by secondary salinity associated with waterlogging. Afforestation is expected to progressively rehabilitate the land, which has a slight slope generating a large environmental gradient. During the rainy season, waterlogging (soil becoming saturated with water) occurred at the lower part of the site, but not at the higher part. The level of salt in the soil (EC1:5) increased gradually from higher to lower ground (0.34—2.7 dS m-1). Tree size and growth rate were negatively related to waterlogging intensity and showed small values at the lower part of the site, with only a slight effect on tree size and growth rate. Moreover, interspecific differences in size and growth rate were observed. Eucalyptus sargentii and E. occidentalis had larger sizes and faster growth rates than E. camaldulensis. Trees planted under waterlogging conditions at the lower part of the site are likely to fail due to poor growth; therefore, afforestation should begin on higher ground where trees would experience normal growth, and in doing so, reduce the soil water content to rehabilitate the land. Improvement of water balance through afforestation would confirm the benefits of appropriate agroforestry management.

Temporally mediated responses of the diversity of coffee mites to agroforestry management

AbstractManaged agroecosystems have been emphasized for their biodiversity, however, it remains unclear how biodiversity is affected by management practices over time. We assessed the seasonal response of the community of coffee‐inhabiting mites to agroforestry management (simple‐shade agroforests, complex‐shade agroforests and abandoned coffee agroforests) in Ecuador. Species richness of coffee mites was negatively affected by management intensification, with more species in less‐disturbed abandoned agroforests compared to simple‐shade agroforests in the dry (but not in the rainy) season. Overall, the community of coffee‐inhabiting mites varied seasonally, with more species and higher densities in the dry season than in the rainy season. In conclusion, our results show that the coffee mite community responded both to seasonal changes and to management of agroforests, and that vegetationally diverse habitats such as complex‐shade and, in particular, abandoned coffee agroforests contribute to the conservation of mite diversity.

Tree seedling establishment in living fences: a low-cost agroforestry management practice for the tropics

Establishing trees in pastures can have production and conservation benefits, but is complicated by the presence of livestock. The need to protect seedlings from livestock increases tree establishment costs, which in turn, can deter landowners from planting trees. Living fences are a ubiquitous feature of pasture landscapes in the tropics that could help protect newly planted trees by preventing livestock trampling and browsing. This study quantified the effectiveness of a living fence in protecting tree seedlings during the first 2 years after planting. The four native tree species evaluated were: Cedrela odorata L., Pachira quinata (Jacq.) W.S. Alverson, Samanea saman (Jacq.) Merr., and Tabebuia rosea (Bertol.) A. DC. Results show that the living fence provided protection from livestock except in cases where tree species were highly palatable as forage (i.e. P. quinata). Trees planted into the living fence generally had greater survival (62 vs. 28%), relative growth (10.3 times initial height vs. 5.8 times initial height), and final height (191 cm vs. 108 cm) compared to those planted in open pasture after 2 years. However, survival and growth of trees planted into the fence remained lower than that observed at a nearby plantation with no livestock, regular weeding and no living fences. This study indicates that use of living fences as a protective barrier could be an effective low-cost approach for establishing trees in tropical pasture landscapes.

Agroforestry management affects coffee pests contingent on season and developmental stage

Abstract1 Management of vegetational diversity in agroecosystems is a potentially regulating factor of pest population dynamics and may affect developmental stages in different ways.2 We investigated the population dynamics of red spider mites, coffee leaf miners, and coffee berry borers in three management types of coffee agroforests: increasing plant diversity from a few shade tree species (simple‐shade agroforests), intermediate‐shade tree species (complex‐shade agroforests) to high‐shade tree species (abandoned coffee agroforests) in Ecuador. Furthermore, we studied how changes in agroforestry management affect population stage structure of each coffee pest.3 Our results show that agroforestry management affected seasonal patterns of coffee pests in that higher densities of red spider mites were observed from August to December, coffee leaf miners from December to February, and coffee berry borers from May to July. Moreover, specific developmental stages of red spider mites, coffee leaf miners, and coffee berry borers differed in their responses to agroforestry management. During all stages, red spider mite reached higher densities in simple‐shade agroforests compared with complex‐shade and abandoned agroforests. Meanwhile, coffee leaf miner densities decreased from simple‐shade to complex‐shade and abandoned agroforests, but only for larvae, not pupae. Similarly, only coffee berry borer adults (but not eggs, larvae and pupae) demonstrated a response to agroforestry management. Environmental variables characterizing each agroforestry type proved to be important drivers of pest population densities in the field.4 We emphasize the importance of considering seasonal differences and population structure while investigating arthropod responses to different habitat types because responses change with time and developmental stages.

‘Fair’ policies for the coffee trade – protecting people or biodiversity?

ABSTRACTWe investigate the role that economic instruments can play in promoting economic sustainability and the preservation of biodiversity in agroforestry management in coffee production. Most of the world's coffee producers live in poverty and manage agro-ecosystems in regions that are culturally and biologically among the most diverse on the globe. Despite the relatively recent finding that bees may augment pollination and boost coffee crop yields, the short-term revenues from intense monoculture drive land-use decisions that destroy the forest strips serving as habitats for pollinating insects. Our study investigates whether farmers specialize in environmentally detrimental (sun-grown) or sustainable (shade-grown) farming, or both practices coexist. We calibrate an empirical model to characterize the equilibria and investigate the ecological and economic impacts of three alternative policy instruments: conservation fees, price premiums, and minimum wages.

From the laboratory to the field: contrasting effects of multi‐trophic interactions and agroforestry management on coffee pest densities

AbstractOnly few factors influencing pest populations can be studied in the laboratory, but many population‐driving factors interact in the field. Therefore, complementary laboratory and field approaches are required for reliable predictions of real‐world patterns and processes. Laboratory and field experiments with the red spider mite, Oligonychus ilicis McGregor (Acari: Tetranychidae), and the coffee leaf miner, Leucoptera coffeella Guérin‐Méneville (Lepidoptera: Lyonetiidae), on coffee plants, Coffea arabica L. (Rubiaceae), were combined to study the relative importance of biotic interactions, including resource preferences and natural‐enemy impact, and habitat factors, such as agroforestry type and management intensity, on coffee pest densities. In the laboratory, leaf discs cut from undamaged coffee plants were significantly preferred by red spider mites over those from plants infested with conspecific mites, leaf rust pathogens [Hemileia vastatrix Berkeley & Broome (Uredinales)], or coffee leaf miners, resulting in higher reproductive success. Similarly, undamaged plants were preferred by coffee leaf miners over red spider mite‐infested plants. However, in the field, red spider mite densities were positively correlated with coffee leaf miner and leaf rust densities, thereby contrasting with laboratory predictions. Hence, our study suggests that the importance of resource preferences and fitness expected based on laboratory experiments was suppressed by environmental conditions in the field, though other unassessed biotic interactions could also have played a role. Furthermore, intensified agroforestry was characterized by higher red spider mite densities, whereas densities of its major natural enemy, the predatory mite Amblyseius herbicolus Chant (Acari: Phytoseiidae), were not related to agroforestry management. Densities of coffee leaf miner and its main natural enemy, a eulophid parasitoid (Hymenoptera), were not affected by management practices. In conclusion, patterns found in the laboratory did not hold for the field, emphasizing the difficulties of extrapolating small‐scale experiments to larger spatial scales and the need to combine both approaches.

Synergies between Agricultural Intensification and Climate Change Could Create Surprising Vulnerabilities for Crops

An inevitable consequence of global climate change is that altered patterns of temperature and precipitation threaten agriculture in many tropical regions, requiring strategies of human adaptation. Moreover, the process of management intensification in agriculture has increased and may exacerbate vulnerability to climate extremes. Although many solutions have been presented, the role of simple agroecological and agroforestry management has been largely ignored. Some recent literature has shown how sustainable management may improve agroecological resistance to extreme climate events. We comment specifically on a prevalent form of agriculture throughout Latin America, the coffee agroforestry system. Results from the coffee literature have shown that shade management in coffee systems may mitigate the effects of extreme temperature and precipitation, thereby reducing the ecological and economic vulnerability of many rural farmers. We conclude that more traditional forms of agriculture can offer greater potential for adapting to changing conditions than do current intensive systems.

Assessing Local Knowledge Use in Agroforestry Management with Cognitive Maps

Small-holder farmers often develop adaptable agroforestry management techniques to improve and diversify crop production. In the cocoa growing region of Ghana, local knowledge on such farm management holds a noteworthy role in the overall farm development. The documentation and analysis of such knowledge use in cocoa agroforests may afford an applicable framework to determine mechanisms driving farmer preference and indicators in farm management. This study employed 12 in-depth farmer interviews regarding variables in farm management as a unit of analysis and utilized cognitive mapping as a qualitative method of analysis. Our objectives were (1) to illustrate and describe agroforestry management variables and associated farm practices, (2) to determine the scope of decision making of individual farmers, and (3) to investigate the suitability of cognitive mapping as a tool for assessing local knowledge use. Results from the cognitive maps revealed an average of 16 +/- 3 variables and 19 +/- 3 links between management variables in the farmer cognitive maps. Farmer use of advantageous ecological processes was highly central to farm management (48% of all variables), particularly manipulation of organic matter, shade and food crop establishment, and maintenance of a tree stratum as the most common, highly linked variables. Over 85% of variables included bidirectional arrows, interpreted as farm management practices dominated by controllable factors, insofar as farmers indicated an ability to alter most farm characteristics. Local knowledge use on cocoa production revealed detailed indicators for site evaluation, thus affecting farm preparation and management. Our findings suggest that amid multisourced information under conditions of uncertainty, strategies for adaptable agroforestry management should integrate existing and localized management frameworks and that cognitive mapping provides a tool-based approach to advance such a management support system.

Environmentally mediated coffee pest densities in relation to agroforestry management, using hierarchical partitioning analyses

Understanding pest density patterns in the field is important to account for distinct environmental variables potentially influencing populations across different habitat types. Here, we assessed the relative importance of single environmental abiotic and biotic variables on densities of three major coffee pests, i.e., spider mites, leaf miners and berry borers, in simple, complex and abandoned agroforests of coastal Ecuador, using hierarchical partitioning methods. Most of the variation in spider mite and leaf miner densities was accounted for by the abiotic variables temperature and relative humidity, while agroforestry type, relative humidity and tree diversity were more important in explaining densities of berry borers. Furthermore, densities of spider mites and berry borers, but not leaf miners, were affected by agroforestry type, with lower densities in structurally complex agroforests. In conclusion, very different environmental variables influence coffee pest population density. Understanding such species density–environmental relationships provide insights on how to predict and manage populations in the field.

The invasive Yellow Crazy Ant and the decline of forest ant diversity in Indonesian cacao agroforests

Throughout the tropics, agroforests are often the only remaining habitat with a considerable tree cover. Agroforestry systems can support high numbers of species and are therefore frequently heralded as the future for tropical biodiversity conservation. However, anthropogenic habitat modification can facilitate species invasions that may suppress native fauna. We compared the ant fauna of lower canopy trees in natural rainforest sites with that of cacao trees in agroforests in Central Sulawesi, Indonesia in order to assess the effects of agroforestry on occurrence of the Yellow Crazy Ant Anoplolepis gracilipes, a common invasive species in the area, and its effects on overall ant richness. The agroforests differed in the type of shade-tree composition, tree density, canopy cover, and distance to the village. On average, 43% of the species in agroforests also occurred in the lower canopy of nearby primary forest and the number of forest ant species that occurred on cacao trees was not related to agroforestry characteristics. However, A. gracilipes was the most common non-forest ant species, and forest ant richness decreased significantly with the presence of this species. Our results indicate that agroforestry may have promoted the occurrence of A. gracilipes, possibly because tree management in agroforests negatively affects ant species that depend on trees for nesting and foraging, whereas A. gracilipes is a generalist when it comes to nesting sites and food preference. Thus, agroforestry management that includes the thinning of tree stands can facilitate ant invasions, thereby threatening the potential of cultivated land for the conservation of tropical ant diversity.

Agroforestry management as an adaptive strategy against potential microclimate extremes in coffee agriculture

Current climate change patterns may cause more extreme and variable climates in the future, threatening agricultural productivity in many areas of the world. Because many smallholder, rural farmers depend on subsistence, rainfed agriculture, priorities should be focused on coping mechanisms that protect these farmers from future vulnerabilities. This paper examines one possible adaptive strategy for coffee agriculture. A high (60–80%), medium (35–65%), and low (10–30%) shade coffee site were chosen in the Soconusco region of Chiapas, Mexico. Microclimate and soil moisture data were collected to examine the ability of shade tree cover in an agroforestry system to protect crop plants against extremes in microclimate and soil moisture fluctuation. Site and site by time effects were analyzed using linear mixed models to compare mean differences of microclimate measurements (temperature, relative humidity, and solar radiation) by site as well as by time of the day. Although there were not large differences in seasonal means for these factors, site by time effects show that temperature, humidity, and solar radiation fluctuations increase significantly as shade cover decreases. Soil data showed significantly larger fluctuations in soil moisture gain and loss in the low shade site respective of patterns of precipitation. Overall, the amount of shade cover was directly related to the mitigation of variability in microclimate and soil moisture for the crop of interest. The use of agroforestry systems is an economically feasible way to protect crop plants from extremes in microclimate and soil moisture and should be considered a potential adaptive strategy for farmers in areas that will suffer from extremes in climate.

Effects of agroforestry on phytoseiid mite communities (Acari: Phytoseiidae) in vineyards in the South of France

The abundance and diversity of phytoseiid mites were surveyed from April to September 2003 to 2005 in vineyards (Grenache and Syrah cultivars) co-planted with rows of Sorbus domestica or Pinus pinea and in monoculture plots of grapes in the South of France. Densities of phytoseiid mites were different on the two tree species, with P. pinea a more suitable host than S. domestica. Typhlodromus (Typhlodromus) exhilaratus was the dominant species occurring on grapes and on co-planted rows of S. domestica and P. pinea, whereas T. (T.) phialatus was the most abundant species in monoculture plots of both S. domestica and P. pinea. Factors determining the dominance of T. (T.) phialatus over T. (T.) exhilaratus in monoculture trees are discussed. In this study, agroforestry management did not affect phytoseiid diversity in vineyards, but did affect phytoseiid density, especially in 2005. The results obtained in 2003 and 2004 are not easy to discuss in this regard because of the low densities of mites observed during these 2 years (very dry climatic conditions and pesticide applications).

Transfer of Knowledge on Agroforestry Management Practices: the Structure of Farmer Advice Networks

Isaac, M. E., B. H. Erickson, S. Quashie-Sam, and V. R. Timmer. 2007. Transfer of knowledge on agroforestry management practices: the structure of farmer advice networks. Ecology and Society 12(2): 32. https://doi.org/10.5751/ES-02196-120232

SHIFTING CULTIVATION, AGROFORESTRY, NON-TIMBER FOREST PRODUCTS AND RELATED LIVELIHOOD SYSTEMS IN LAOS: A CASE STUDY

SUMMARY The government of the Lao PDR has plans to eliminate shifting cultivation by 2010 and poppy growing in 2006. These practices were examined. In 2000, they covered 680,000 ha in upland areas and involved 344,000 farming families. The principal practical alternatives to shifting cultivation such as agroforestry systems, the expansion of non-timber forest products (NTFPs) and related livelihood systems are discussed in detail as well as government policies and initiatives to promote them. At present, the government has punitive laws concerning shifting cultivation and most gathering of NTFPs is officially illegal. But it is only just starting to encourage sustainable land use practices. Existing initiatives are discussed and plans are proposed to promote agroforestry and sustainable non-timber forest products management and use as part of a viable strategy to eliminate shifting cultivation and provide alternatives to poppy growing. This must be done with the active cooperation and participation of the upland farmers.