Thilak Mallawaarachchi

Water Use and Salinity in the Murray-Darling Basin: A State-Contingent Model

The supply of water for irrigation is subject to climatic and policy uncertainty. The object of the present paper is to show how the linear and non-linear programming models commonly used in modelling problems such as those arising in the Murray-Darling Basin may be adapted to incorporate a state-contingent representation of uncertainty. Estimates showing the potential value of improved water use are also derived.

GIS-based integrated modelling systems for natural resource management

Abstract Natural resource management relies on the use of resource, economic and production data, which are often available at various non-comparable scales. This causes serious problems in data interpretation and on the availability and cross-compatibility of official data for detailed modelling and analysis. Integration of the spatial analytical capabilities of Geographic Information Systems and the constraint optimization power of mathematical programming facilitates the generation of composite data sets for extensive geographic regions. Integrated modelling offers the capacity to examine the effects of interacting properties of economic and natural systems. This paper presents an application of a modelling system for the assessment of land degradation costs in extensive areas of the state of New South Wales, Australia. It highlights the potential of the system to evaluate the feasibility of policy alternatives and program options at a broader regional level.

Modelling socially optimal land allocations for sugar cane growing in North Queensland: a linked mathematical programming and choice modelling study {

A modelling framework is developed to determine the joint economic and environmental net benefits of alternative land allocation strategies. Estimates of community preferences for preservation of natural land, derived from a choice modelling study, are used as input to a model of agricultural production in an optimisation framework. The trade‐offs between agricultural production and environmental protection are analysed using the sugar industry of the Herbert River district of north Queensland as an example. Spatially‐differentiated resource attributes and the opportunity costs of natural land determine the optimal trade‐offs between production and conservation for a range of sugar prices.

Ecosystem services from a degraded peatland of Central Kalimantan: implications for policy, planning, and management

Increasingly, landscapes are managed for multiple objectives to balance social, economic, and environmental goals. The Ex-Mega Rice Project (EMRP) peatland in Central Kalimantan, Indonesia provides a timely example with globally significant development, carbon, and biodiversity concerns. To inform future policy, planning, and management in the EMRP, we quantified and mapped ecosystem service values, assessed their spatial interactions, and evaluated the potential provision of ecosystem services under future land-use scenarios. We focus on key policy-relevant regulating (carbon stocks and the potential for emissions reduction), provisioning (timber, crops from smallholder agriculture, palm oil), and supporting (biodiversity) services. We found that implementation of existing land-use plans has the potential to improve total ecosystem service provision. We identify a number of significant inefficiencies, trade-offs, and unintended outcomes that may arise. For example, the potential development of existing palm oil concessions over one-third of the region may shift smallholder agriculture into low-productivity regions and substantially impact carbon and biodiversity outcomes. While improved management of conservation zones may enhance the protection of carbon stocks, not all biodiversity features will be represented, and there will be a reduction in timber harvesting and agricultural production. This study highlights how ecosystem service analyses can be structured to better inform policy, planning, and management in globally significant but data-poor regions.

Disaggregating Agricultural Statistics Using NOAA-AVHRR NDVI

Linking the results of remote sensing with production statistics to create land-use maps is problematic. This article presents a technique that integrates two significant data sets relating to agricultural land-use, namely, survey-based production statistics and vegetation growth profiles derived from satellite data. The article describes an application of this technique in which production data from an administrative survey are used to constrain the classification of NDVI profiles of land cover classes. Because the technique reallocates aggregated production statistics consistent with low-resolution imagery and with limited ground control information, it is a particularly cost-effective method of extensive land-use mapping.

Mixed policies give more options in multifunctional tropical forest landscapes

Tropical forest landscapes face competing demands for conserving biodiversity, sustaining ecosystem services and accommodating production systems such as forestry and agriculture. Land-sparing and land-sharing have emerged as contrasting strategies to manage trade-offs between production and biodiversity conservation. Both strategies are evident in land-management policies at local-to-international scales. However, studies rarely report the impacts of these strategies, assessed for multiple stakeholders and multiple ecosystem services, particularly in real landscapes. Using a case study from a high-priority region for forest protection, restoration and rural development in Central Kalimantan, Indonesia, we analysed the potential outcomes under 10 alternative policy scenarios, including land-sharing, land-sparing and mixed strategies. We used a novel optimization process integrating integer programming with conservation-planning software (Marxan with Zones) to identify production possibility frontiers (PPFs), highlighting the trade-off between smallholder agriculture and oil palm, subject to achievement of a set of carbon, timber and biodiversity conservation targets. All policy scenarios modelled proved to be capable of achieving all targets simultaneously. Most strategies resulted in an expansion of the PPF from the baseline, increasing the flexibility of land allocation to achieve all targets. Mixed strategies gave the greatest flexibility to achieve targets, followed closely by land-sparing. Land-sharing only performed better than the baseline when no yield penalties were incurred, and resulted in PPF contraction otherwise. Strategies assessed required a minimum of 29-37 to be placed in conservation zones, notably protecting the majority of remaining forest, but requiring little reforestation. Policy implications. Production possibility frontiers (PPFs) can evaluate a broad spectrum of land-use policy options. When using targets sought by multiple stakeholders within an ecosystem services framework, PPFs can characterize biophysical, socio-economic and institutional dimensions of policy trade-offs in heterogeneous landscapes. All 10 policy strategies assessed in our case study are biophysically capable of achieving all stakeholder objectives, provided at least 29-37 of the landscape is conserved for biodiversity. This novel methodological approach provides practical options for systematic analysis in complex, multifunctional landscapes, and could, when integrated within a larger planning and implementation process, inform the design of land-use policies that maximize stakeholder satisfaction and minimize conflict. © 2016 The Authors. Journal of Applied Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

State‐contingent analysis of farmers’ response to weather variability: irrigated dairy farming in the Murray Valley, Australia

The agricultural sector is commonly regarded as one of the most vulnerable to climate change. Current understanding of the impact of climate change on this sector relies on the underlying assumptions about farmers’ possible responses to weather variability, including changes in crop choice, input combinations and land management practices. Many previous analyses rely on the implicit (and restrictive) assumption that farmers operate under a fixed technology set across different states of nature. This assumption, represented through stochastic production or profit functions, is commonly made but seldom tested, and may understate farmers’ responses to climate change if state-contingent production technologies are, in reality, more flexible. The potential for farmers to adapt production technologies in response to unforeseen events is at the core of the state-contingent approach. Advanced in Chambers and Quiggin (2000), the theory contends that producers can manage uncertainty through the allocation of productive inputs to different states of nature. In this article we test the assumption that farmers’ observed behaviour is consistent with the state-contingent production theory using farm-level data from Australia. More precisely, we estimate the milk production technology for a sample of irrigated dairy farms from the southern Murray–Darling Basin over the period from 2006-07 to 2009-10.

Agricultural adaptation: observations and insights

It has been recognized for some time that the benefits of climate change mitigation efforts will come too late to avoid substantial impacts from expected changes in the climate. It has also been acknowledged that scientific uncertainties prevent a firm understanding of how the effects of climate change will be distributed across sectors and locations, as well as through time (Garnaut, 2008; Tol, 2012). In this setting, it will be essential for farmers (and others) to adapt to changes in agronomic conditions that they face over time. Adaptation will be undertaken both in anticipation of change and in response to changes being experienced and the quantum, type and timing of adaptation responses by different firms and individuals will vary depending on their perception of change and its consequences. A key issue in understanding the role of public policy around adaptation is whether adaptation is likely to be insufficient or ineffective if left to autonomous adjustment led by market forces alone. It is well known that agriculture is highly exposed to climate variation and climate change presents a significant threat to improving agricultural productivity. It is also known that Australian agriculture has been engaged in an ongoing process of adaptation and evolution since European settlement. The sector is characterized by many comparatively small and heterogeneous producers, interacting directly with prevailing climatic and biological conditions. The sector continually confronts risk associated with climate and biology (production risk) and market volatility (market risk).