Jackson L.,University of California at Davis |
van Noordwijk M.,World Agroforestry Center South East Asia |
Bengtsson J.,Swedish University of Agricultural Sciences |
Foster W.,University of Cambridge |
And 5 more authors.
Current Opinion in Environmental Sustainability | Year: 2010
Rapid changes in land use, food systems, and livelihoods require social-ecological systems that keep multiple options open and prepare for future unpredictability. Sustainagility refers to the properties and assets of a system that sustain the ability (agility) of agents to adapt and meet their needs in new ways. In contrast, sustainability tends to invoke persistence along current trajectories, and the resilience to return to current baselines. With three examples, the use and conservation of agrobiodiversity is explored along temporal, spatial, and human institutional scales for its role in sustainagility: first, farmers' seed systems; second, complex pollination systems; and third, wildlife conservation in agricultural areas with high poverty. Incentives are necessary if agrobiodiversity is to provide benefits to future generations. © 2010 Elsevier B.V.
Martin F.S.,World Agroforestry Center South East Asia |
Bertomeu M.,National Agriculture and Forestry Research Institute NAFRI |
van Noordwijk M.,World Agroforestry Center South East Asia |
Navarro R.,University of Cordoba, Spain
Small-scale Forestry | Year: 2012
The 'when, where and how' of decisions by smallholder upland farmers to plant trees as part of their use of natural, human and capital resources needs to be understood if policy support is to result in actual recovery of tree cover as part of a 'forest transition' trajectory. In large parts of the Philippines the turning point may be close. Data on resource access and tree planting decisions were gathered from a household survey, with a total of 148 respondents in four rural communities in Leyte Province in Central Philippines. Data were analysed using logistic regression analysis. Household-level results reveal that the outcomes of the decision-making processes primarily depend on the availability of land and access to remaining forest resources rather than socio-cultural or economic factors. The total area of land and number of parcels managed by the household plus security of land tenure through ownership was found to have a statistically significant effect on farmers' decision to plant native timber trees. Access to surrounding natural forest is negatively associated with farmer tree planting. © 2011 Steve Harrison, John Herbohn.
Vincent G.,IRD Montpellier |
Vincent G.,World Agroforestry Center South East Asia |
Joshi L.,World Agroforestry Center South East Asia |
Susilawaty,World Agroforestry Center South East Asia
Forests Trees and Livelihoods | Year: 2011
Rubber production and yield components (tree density, number of trees tapped per day, number of tapping days per year) were monitored in 35 plots of rubber agroforests in Jambi province (Sumatra) for one year. The results showed a great variability in yield components both between plots and over time. The overall average production of dry rubber per tree per tapping day was 17g, which is about half of the production per tree per tapping day that can be attained in well managed plantations of selected rubber clones. Productivity per ha and per year appeared to be further reduced by the low number of rubber trees per ha (c. 50% of the trees above 10 cm dbh are not rubber trees), the selective tapping of only a fraction of the population of rubber trees of tappable size and the low number of tapping days per year. Low average tapping frequency (110 days) was related to low prices prevailing during the study period. Tapping frequency appeared to be further influenced by a number of case specific factors including the degree of dependence of farmers on latex as a source of income, labor availability (for the plot owner) and presence or absence of other work opportunities (for the share-tapper). As a result of this opportunistic exploitation, the actual annual production per unit area in rubber agroforests appears to be often below maximum potential production of the plot. It is argued that the high flexibility of this extensive rubber cultivation system compensates for its low productivity and largely determines its wide adoption. It is further suggested that the opportunistic exploitation of extensively managed rubber agroforests may fulfil an important social function as it appears to serve as a reservoir of paid labour. © 2011 A B Academic Publishers.
Mercado Jr. A.R.,University of Hohenheim |
Mercado Jr. A.R.,World Agroforestry Center South East Asia |
Van Noordwijk M.,World Agroforestry Center South East Asia |
Cadisch G.,University of Hohenheim
Agroforestry Systems | Year: 2011
Nitrogen inputs from biological nitrogen fixation contribute to productivity and sustainability of agroforestry systems but they need to be able to offset export of N when trees are harvested. This study assessed magnitudes of biological nitrogen fixation (natural 15N abundance) and N balance of Acacia mangium woodlots grown in farmer's fields, and determined if N2 fixation capacity was affected by tree age. Tree biomass, standing litter, understory vegetation and soil samplings were conducted in 15 farmer's fields growing A. mangium as a form of sequential agroforestry in Claveria, Misamis Oriental, Philippines. The trees corresponded to ages of 4, 6, 8, 10 and 12 years, and were replicated three times. Samples from different plant parts and soils (0-100 cm) were collected and analyzed for δ15N and nutrients. The B-value, needed as a reference of isotopic discrimination when fully reliant on atmospheric N, was generated by growing A. mangium in an N2-free sand culture in the glasshouse. Isotopic discrimination occurring during N2 fixation and metabolic processes indicated variation of δ15N values in the order of nodules > old leaves > young leaves > stems > litterfall and roots of the trees grown in the field, with values ranging from -0.8 to 3.5‰ except nodules which were enriched and significantly different from other plant parts (P < 0.0001). Isotopic discrimination was not affected by tree age (P > 0.05). Plants grown in N free sand culture exhibited the same pattern of isotopic discrimination as plants grown in the field. The estimated B-value for the whole plant of A. mangium was -0.86‰. Mature tree stands of 12 years accumulated up to 1994 kg N ha-1 in aboveground biomass. Average proportion of N derived from N2 fixation of A. mangium was 54% (±22) and was not affected by age (P > 0.05). Average yearly quantities of N2 fixed were 128 kg N ha-1 in above-ground biomass amounting to 1208 kg N fixed ha-1 over 12 years. Harvest of 12-year old trees removed approximately 91% of standing aboveground biomass from the site as timber and fuel wood. The resulting net N balance was +151 kg N ha-1 derived from remaining leaves, twigs, standing litter, and +562 kg N ha-1 when tree roots were included in the calculation. The fast growing A. mangium appears to be a viable fallow option for managing N in these systems. However, other nutrients have to be replaced by using part of the timber and fuel wood sales to compensate for large amounts of nutrient removed in order for the system to be sustainable. © 2010 Springer Science+Business Media B.V.
Martin F.S.,University of Cordoba, Spain |
Navarro-Cerrillo R.M.,University of Cordoba, Spain |
Mulia R.,World Agroforestry Center South East Asia |
van Noordwijk M.,World Agroforestry Center South East Asia
Agroforestry Systems | Year: 2010
Fractal branching models can provide a non-destructive and generic tool for estimating tree shoot and root length and biomass, but field validation is rarely described in the literature. We compared estimates of above ground tree biomass for four indigenous tree used on farm in the Philippines based on the WanFBA model tree architecture with data from destructive sampling. Allometric equations for the four species varied in the constant (biomass at virtual stem diameter 1) and power of the scaling rule (b in Y=aDb), deviating from the value of 8/3 that is claimed to be universal. Allometric equations for aboveground biomass were 0.035 D2.87 for Shorea contorta, 0.133 D2.36 for Vitex parviflora, 0.063 D2.54 for Pterocarpus indicus and 0.065 D2.28 for Artocarpus heterophyllus, respectively. Allometric equations for branch biomass had a higher b factor than those for total biomass (except in Artocarpus); allometric equations for the leave+twig fraction a lower b. The performance of the WanFBA model was significantly improved by introduction of a tapering factor "τ" for decrease of branch diameter within a single link. All statistical tests performed on measured biomass versus biomass predicted from the WanFBA results confirm the viability of the WanFBA model as a non-destructive tool for predicting above-ground biomass equations for total biomass, branch biomass and the leaf+twig fraction. © Springer Science+Business Media B.V. 2010.