Betha Lusiana

WaNuLCAS, a model of water, nutrient and light capture in agroforestry systems

Models of tree-soil-crop interactions in agroforestry should maintain a balance between dynamic processes and spatial patterns of interactions for common resources. We give an outline and discuss major assumptions underlying the WaNuLCAS model of water, nitrogen and light interactions in agroforestry systems. The model was developed to deal with a wide range of agroforestry systems: hedgerow intercropping on flat or sloping land, fallow-crop mosaics or isolated trees in parklands, with minimum parameter adjustments. Examples are presented for simulation runs of hedgerow intercropping systems at different hedgerow spacings and pruning regimes, a test of the safety-net function of deep tree roots, lateral interactions in crop-fallow mosaics and a first exploration for parkland systems with a circular geometry.

Users’ perspectives on validity of a simulation model for natural resource management

Managers of agro-ecosystems trade off food production and livelihood strategies against environmental services. They need tools to prospect a wide range of external conditions. Integrated simulation models allow stakeholders to discuss the plausible behaviour of agro-ecosystems and to evaluate dynamic trade-offs, as a basis for planning and policy making in agriculture and natural resource management. However, simulation models need to gain stakeholders’ acceptance before they will be utilized. Gaining stakeholders’ acceptance likely requires salience, credibility and legitimacy. We surveyed the perceptions and expectations of 122 potential model users in four countries, prioritizing these model attributes. A possible shift in user perception was assessed during a participatory model evaluation of a resource management model (FALLOW) for post-tsunami development in West Aceh (Indonesia). Potential model users, comprising natural resource managers, policy makers, lecturers and scientists, ranked salience as the most important characteristic for an integrated simulation model, followed by credibility and legitimacy. Model users’ occupation, prior exposure and interest in using a simulation model did not have a statistically significant influence on users’ perceptions of model attributes.

Diversity deficits in modelled landscape mosaics

Abstract We outline several diversity factors that modellers and models can include directly or indirectly in order to improve the accuracy and usefulness of the model. Without considering these factors, different types of diversity deficit can arise. These deficits can be considered in three domains: 1) in the real world where actual diversity is less than a potential state that is deemed desirable (hence we worry about loss of biodiversity and cultural diversity); 2) in modelling of the real world (where ‘residual variance’ may represent a diversity deficit of the model); and 3) in our recognition of the driving forces that are used to construct a model (a diversity deficit due to oversimplification). The goal of this review is to use these three domains of diversity deficit to evaluate existing models, with a longer term goal of creating a more robust framework for assessing landscape models in the future. To that end, we evaluate the behaviour characteristics and routines of agents in some current models. We also address one of the fundamental challenges to modelling diversity, which is the integration of non-economic motivations in the decision making of human agents.

Agroforestry solutions for buffering climate variability and adapting to change.

Th is chapter will focus on increasing the adaptive capacity of agricultural systems in tropical and subtropical regions through agroforestry. Agroforestry as a concept resists and tries to counteract the way agriculture has been segregated from forests and forestry. Understanding, using and improving agroforestry implies a focus on the interactions between trees, annual crops and domestic stock, given the local abiotic factors of climate, soils, water and nutrient balances, as well as the biotic context (pests, diseases, antagonists, predators, pollinators and dispersal agents), and the use of land, external inputs, labour and knowledge. We pose and review the hypothesis that the presence of trees increases the degree of buff ering of climate variability from the perspective of an annual food crop, and that retention and the increase of trees in agricultural landscapes can be a relevant part of climate change adaptation strategies.

Mud, muddle and models in the knowledge value-chain to action on tropical peatland conservation

Tropical peatlands are known not only for their high, area-based, carbon emissions in response to land-use change but also as hot spots of debate about associated data uncertainties. Perspectives are still evolving on factors underlying the variability and uncertainty. Debate includes the ways of reducing emissions through rewetting, reforestation and agroforestry. A knowledge value-chain that is long and complex links (a) fundamental understanding of peat and peatland processes leading to sciencebased quantification and default values, (b) willingness and (c) ability to act towards emission reduction, and ultimately (d) to local, national and global actions that effectively provide rules, incentives and motivation to conserve peat and reduce emissions. We discuss this value chain, its stakeholders and issues that still remain partially unresolved. We conclude that, to shorten the denial and conspiracy-theory stages of debate that otherwise slow down steps B and C, networks of international and national scientists have to be involved at the early stage of identifying policysensitive environmental issues. Models span part of the knowledge value-chain but transition of analysis units requires specific attention, from soil volumes through area and commodity flows to opportunities for reductions. While drainage of peatlands triggers landscape-scale increases in emissions, factors beyond drainage depth, including nutrient supply, may have a major influence on decomposition rates. Attempts to disentangle the contributions of plant and peat-based respiration in surface flux measurements involve assumptions that cannot be easily verified in comparisons between land uses. With progress on A leading to new internationally accepted defaults and with resistance on step B reduced, the reality of C and lack of working solutions for D is currently constraining further progress.

Discourses on the performance gap of agriculture in a green economy: a Q-methodology study in Indonesia

ABSTRACT Gaps exist between aspirations of ‘green agriculture’, which protects biodiversity and ecosystem services, and the reality on the ground. Using Q-methodology, we explored expert opinion in Indonesia on the contributing factors to the gaps. Q-methodology indicated three dominant discourses on ‘green agriculture’ and groups of experts who prioritize them: (1) endorsers of regulations and innovations; (2) providers of resources for access to capital, technology and knowledge; and (3) proponents of green economy (GE) and land-use planning (LUP). Group 1 pointed out the importance of endorsing incentives to reduce the gap, while Group 2 reckoned that building smallholders’ capacity and providing them with access to capital, technology, and knowledge are needed to green agricultural practices. Group 3 described the importance of integrating environmental value into the gross domestic product and earmarking sources derived from environmental levies for greening the agricultural sector. All discourses recognized the importance of scientific policy formulation. Groups 1 and 3 agreed that non-synchronization of LUP between national and local governments highly contributes to the gap. Groups 2 and 3 perceived that ecosystem services from the agricultural sector have not been sufficiently understood to promote green agricultural development. By simultaneously addressing the gaps on each level and understanding how each factor contributes to the gap, we propose a set of recommendations to improve the implementation of green agriculture in Indonesia by creating a platform that all three groups can recognize and support. EDITED BY Dagmar Mithöfer

Agroforestation of Grasslands in Southeast Asia: WaNuLCAS Model Scenarios for Shade-Based Imperata Control During Tree Establishment

In the stage of land use evolution where smallholder tree-based systems are desirable as replacement of Imperata cylindrica (and similar) grasslands, agroforestry can provide a gradual and rewarding approach to the transition. There tends to be, however, a gap between the last opportunity for food crop interplanting and canopy closure providing shade-based control of grass and weed growth. In such period, regrowth of Imperata enhances the risk of fire and failure of tree establishment. We analyzed the duration of this ‘Imperata regrowth window’, for a range of planting patterns and choice of tree species in Lampung (Indonesia) and northern Mindanao (the Philippines). Simulations of agroforestation scenarios with the WaNuLCAS model (‘water, nutrient and light capture in agroforestry systems’) focuss on the Imperata regrowth window as the period between 50 percent and 15 percent of ground-level light availability.