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Forests Sustaining Agriculture
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Side Event at the 2020 Global Landscapes Forum Bonn: Contribution of Forests, Trees and Agroforestry to sustainable Food Security and Nutrition in a time of crisis. Presented by Terry Sunderland, James Reed and Joli Borah.
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Forests Sustaining Agriculture
- Forests Sustaining Agriculture Side Event: Contribution of Forests, Trees and Agroforestry to sustainable Food Security and Nutrition in a time of crisis Global Landscapes Forum, Bonn June 3rd 2020 Terry Sunderland, James Reed and Joli Borah
- Introduction • Ecosystem services (ES) are regarded as the structure and functions of ecosystems that result in both goods and services being produced that contribute to support human wellbeing. • The last three decades has seen an exponential rise in ecosystem service related publications. • However, the contribution of trees to adjacent or embedded food systems remains poorly understood • Assessment of the literature base for both the positive (ES) and negative (EDS) functions of forests, trees and agroforestry in relation to food production (Reed et al. 2017).
- Forests sustaining agriculture How does landscape configuration maximise the provision of these goods and services for both sustainable forestry and food production? Water regulation Climate regulation Pollination Pest control Foli et al. 2014; Reed et al. 2017
- “When incorporating forests and trees within an appropriate and contextualized natural resource management strategy, there is potential to maintain, and in some cases, enhance agricultural yields comparable to solely monoculture systems”. Reed et al. 2017
- Forests sustaining agriculture Nutrient Cycling: Studies conducted in agroforestry systems (AFS): 79% showed a positive effect of tree presence Pollination: 87% of studies showed a positive effect of nearby (0.3 – 1.6km) forest/forest fragment. Pollination and nutrition linkages Climate regulation: Yields of some crops diminish, further from forests Forests, trees = resilience (Foli et al. 2014 Env. Evidence; Ellis et al 2015, Plos One)
- Trees in wheat fields increase nitrogen availability in soil, water use efficiency, reduces heat stress and increases yield…. Sida et al 2018: Climate-smart agroforestry: Faidherbia albida trees buffer wheat against climatic extremes in the Central Rift Valley of Ethiopia. Agricultural and Forest Meterology, 248: 339-347.
- Nutritional value of crops increases with proximity to forest… Wood et al. 2018: Nutritional value of crops increased with proximity to forest through improved soil organic matter in wheat fields in Ethiopia. Agriculture, Ecosystems and Environment. 266:100-108.
- Duriaux Chavarría et al.. 2018. Retaining forests within agricultural landscapes as a pathway to sustainable intensification: evidence from Southern Ethiopia. Agriculture, Ecosystems and the Environment, 263: 41-52. Livestock productivity and nutrient balances improve with increasing proximity to forest….
- Shade trees decrease the abundance of pests…. Figure 1 Figure 2 Guenat et al. 2019: Shade trees decrease pest abundances on brassica crops in Kenya. Agroforestry Systems, 93: 641-652.
- Shade tree diversity enhances coffee production and crop quality in agroforestry systems…. Photo: Wiki commons Nesper et al. 2017: Shade tree diversity enhanced coffee production and quality in agroforestry systems in the Western Ghats. Agriculture, Ecosystems and Environment, 247: 172-181.
- Evergreen Agriculture……. Garrity et al., 2010. Evergreen Agriculture: a robust approach to sustainable food security in Africa. Food Security, 2:197–214
- THINKING beyond the canopy Key messages • Diverse forest and tree-based production systems offer advantages over monocropping systems because of their adaptability and resilience. • There are a multitude of ecosystem services provided by forests and trees that simultaneously support food production, nutrition, sustainability and environmental and human health. • Managing landscapes on a multi-functional basis that combine food production, biodiversity conservation and the maintenance of ecosystem services can contribute to food and nutritional security • Forests and trees alone will not achieve global food security, but can play a major role: discourse has started to change
- Thank you! Terry Sunderland: terry.Sunderland@ubc.ca James Reed: j.reed@cgiar.org Joli Borah: joli.borah@ubc.ca @TCHSunderland @James_D_Reed @JoliBorah
Editor's Notes
- Sida et al 2018: Incorporating trees in wheat fields increased nitrogen availability in soil, water use efficiency, reduced heat stress and increased yield significantly compared to wheat fields without trees in Central Rift Valley of Ethiopia. The study carried out an on-farm experiment for three consecutive seasons in the with treatments of Faidherbia trees with bare soil underneath, wheat grown beneath Faidherbia and wheat grown in open fields. They tested the sensitivity of wheat yield to tree-mediated variables of photosynthetically active radiation (PAR), air temperature and soil nitrogen. The results showed soil moisture in the sub-soil was the least for wheat with tree, intermediate for sole tree and the highest for open field. Presence of trees resulted in 35–55% larger available N close to tree crowns compared with sole wheat. Trees significantly reduced PAR reaching the canopy of wheat growing underneath to optimum levels. Midday air temperature was about 6 °C less under the trees than in the open fields. LAI, number of grains spike−1, plant height, total aboveground biomass and wheat grain yield were all significantly higher (P < 0.001) for wheat associated with F. albida compared with sole wheat. Model-based sensitivity analysis showed that under moderate to high rates of N, wheat yield responded positively to a decrease in temperature caused by F. albida shade. Figure 1: Graphical abstract of the study Figure 2: Localized microenvironment modification by F. albida: available nitrogen (a), photosynthetically active radiation (PAR) (b) as a function of distance from the trunk of trees and diurnal variation in air temperature under and outside the canopy of F. albida between anthesis and grain filling stages (c). Graphs were generated from the means of two seasons, except for available nitrogen. The error bars are standard deviations. Figure 3: Grain yield (a) and total above ground biomass (b) as a function of distance from the trunk of F. albidain 2014. The error bars represent the standard deviations.
- Wood et al. 2018: Nutritional value of crops increased with proximity to forest through improved soil organic matter in wheat fields in Ethiopia. Study details: They measured soil organic matter fractions, crop yield, and wheat nutrient composition on smallholder farms along a land-use and land-cover gradient in Ethiopia. They found that wheat yields and protein content were related to organic matter nitrogen, and zinc content was related to organic matter carbon. Increasing organic matter carbon by 1% was associated with an increase in zinc equivalent to the needs of 0.2 additional people per hectare; increasing organic matter nitrogen by 1% was associated with an increase in protein equivalent to the daily needs of 0.1 additional people per hectare. Soil organic matter—and its associated fractions—was greatest in soils closest to a state forest and in home gardens (as opposed to in wheat fields). Wheat fields closer to the forest had elevated soil organic matter fractions relative to wheat soils closest to the market town. Figure description: Wheat model standardized coefficient plots showing the relative effect size of variables within a model, for yield (A), protein (B), zinc (C), and iron (D). Black vertical line is 0. Red bars indicate 80% of full distribution, black bars indicate 95%, and points are coefficient median values. Here, Near forest=. Middle zone=villages 3 km from forest, N addition, MAOM N=mineral-associated organic matter, POM N=particulate organic matter N, .
- Duriaux Chavarría et al. 2018: Livestock productivity and nutrient balances can improve with increasing proximity to forest as evidenced in Southern Ethiopia Detailed study: Using a landscape in Southern Ethiopia comprised of three zones of increasing distance from a legally protected forestas a case study, the performance of a stratified sample of 27 farms was assessed through detailed surveys and empirical measurements. While livestock productivity was found to be higher closer to the forest, no difference was found for crop or total farm productivities across the three zones. Partial nutrient balances (a productivity dimension of farm sustainability), redundancy (a proxy of resilience), and equality in the distribution of livestock increased with increasing proximity to the forest. Dependency on external inputs also decreased with increasing proximity to the forest. Fig 1: the dependency of the system on external inputs which accounts for the negative effect that external changes—-e.g. changes in input prices, access to inputs-could have on the functions of the system Fig 2: Output as a function of input for (a) carbon, (b) nitrogen, (c) phosphorus and (d) potassium. N = 27 farms. The partial C balance tended to decrease with increasing distance from the forest. The partial N balance decreased with increasing distance from the forest. All farms in the study area had a positive partial P balance with the exception of two farms in the distant zone (Fig. c). The mean P balance of farms in the near zone was more than double that of the farms further away from the forest. Five farms in the distant zone and one in the intermediate zone had a negative partial K balance (Fig. d).
- Guenat et al. 2019: Shade trees decrease pest abundances on brassica crops in Kenya Study: assessed pest abundances and biological control potential in shaded and open kale (Brassica oleracea L. acephala) fields in Western Kenya. They compared the abundance of pest aphids and caterpillars, ground-dwelling ants, spiders and predatory beetles, and examined aphid parasitism rates, predation rates on diamondback moth eggs, attack rates on surrogate caterpillars and bird predation on aphids. Shade trees effectively reduced abundances of aphids, caterpillars and increased abundances of spiders and predatory beetles, but neither affected ant abundances, or predation and parasitism rates. The presence of shade trees can decrease pest abundances, but that this is not only due to improved biological control by natural enemies but also due to microclimatic conditions affecting pest performance and bottom-up processes such as changes in plant quality and soil conditions. Fig: 1. Illustration of the two treatments: a an open field, in Hotutu, and b a field surrounded by shade trees, in Yuya 2. Number per field of a aphids per leaf (n = 40), with each dot representing the average number per leaf per field, and b moth caterpillars (n = 20), with each dot representing the total abundance per field, in open and shaded fields. Boxes show median and interquartile ranges for each site type, with the whiskers extending to 1.5 of the interquartile range
- Nesper et al. 2017: Shade tree diversity enhanced coffee production and quality in agroforestry systems in the Western Ghats Study: The study investigated how tree biodiversity and its effects on coffee production and quality changes along a gradient of intensification (from diverse multispecies to Grevillea robusta dominated shade) across 25 Coffea canephora agroforests in Kodagu, India. Intensification caused a marked reduction in tree biodiversity (Shannon’s diversity: 2.74 to 0.29). Reduced tree diversity negatively affected both coffee production and quality (in terms of bean size), and increased incidences of pest attack, the coffee berry borer (Hypothenemus hampei). These results were consistent across a broad rainfall gradient (1060 mm yr−1 to 4370 mm yr−1) and management systems (conventional vs. organic farming and irrigation). Figure: Relation between Shannon’s diversity and shade tree Grevillea robusta density measured at plot level (1257 m2). Regression lines are based on predictions from general additive models with smoothing terms estimated by generalized cross validation, 95% confidence intervals were generated through prediction (grey shading).
- Garrity et al 2010: Evergreen Agriculture i.e. the integration of particular tree species into annual food crop systems sustain a green cover on the land throughout the year to maintain vegetative soil cover, bolster nutrient supply through nitrogen fixation and nutrient cycling, generate greater quantities of organic matter in soil surface residues, improve soil structure and water infiltration, increase greater direct production of food, fodder, fuel, fiber and income from products produced by the intercropped trees, enhance carbon storage both above-ground and below-ground, and induce more effective conservation of above- and below-ground biodiversity. Four national cases are reviewed where farmers are observed to be applying these principles on a major scale. Zambia, where conservation farming programmes include the cultivation of food crops within an agroforest of the fertilizer tree Faidherbia albida. Malawi Agroforestry Food Security Programme, which is integrating fertilizer, fodder, fruit, fuel wood, and timber tree production with food crops on small farms on a national scale. The dramatic expansion of Faidherbia albida agroforests in millet and sorghum production systems throughout Niger via assisted natural regeneration. The development of a unique type of planting pit technology (zai) along with farmer-managed natural regeneration of trees on a substantial scale in Burkina Faso. Fig 1: Maize exhibit dramatic productivity increases in association with Faidherbia albida. Note differences in maize growth under the tree versus outside the canopy with the same management practices applied and zero inorganic fertilization. Zambia, 2009. Photo: D Garrity Fig 2: Two promising fertilizer tree systems in Malawi: a) Faidherbia trees intercropped with maize, and b) Gliricidia managed as a coppice shrub in maize fields Photos: D Garrity
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