MODELING TROPICAL DEFORESTATION: A SURVIVAL ANALYSIS LINKING SATELLITE AND HOUSEHOLD SURVEY DATA

This research estimates a hazard model of forest conversion in southern Mexico using geographical information systems, household survey data, and satellite imagery. A utility-maximizing model consistent with agricultural frontier conditions is developed. The econometric methodology incorporates temporal dynamics into the otherwise static range of analyses possible using categorical satellite data.Resource /Energy Economics and Policy,

Estimation of evapotranspiration and crop coefficients of tendone vineyards using multi-sensor remote sensing data in a mediterranean environment

The sustainable management of water resources plays a key role in Mediterranean viticulture, characterized by scarcity and competition of available water. This study focuses on estimating the evapotranspiration and crop coefficients of table grapes vineyards trained on overhead "tendone" systems in the Apulia region (Italy). Maximum vineyard transpiration was estimated by adopting the "direct" methodology for ETp proposed by the Food and Agriculture Organization in Irrigation and Drainage Paper No. 56, with crop parameters estimated from Landsat 8 and RapidEye satellite data in combination with ground-based meteorological data. The modeling results of two growing seasons (2013 and 2014) indicated that canopy growth, seasonal and 10-day sums evapotranspiration values were strictly related to thermal requirements and rainfall events. The estimated values of mean seasonal daily evapotranspiration ranged between 4.2 and 4.1 mm·d-1, while midseason estimated values of crop coefficients ranged from 0.88 to 0.93 in 2013, and 1.02 to 1.04 in 2014, respectively. The experimental evapotranspiration values calculated represent the maximum value in absence of stress, so the resulting crop coefficients should be used with some caution. It is concluded that the retrieval of crop parameters and evapotranspiration derived from remotely-sensed data could be helpful for downscaling to the field the local weather conditions and agronomic practices and thus may be the basis for supporting grape growers and irrigation managers

Economic Valuation of Environmental Benefits and the Targeting of Conservation Programs: The Case of the CRP

The range of environmental problems confronting agriculture has expanded in recent years. As the largest program designed to mitigate the negative environmental effects of agriculture, the Conservation Reserve Program (CRP) has broadened its initial focus on reductions in soil erosion to consider other landscape factors that may also be beneficial. For example, preserving habitats can help protect wildlife, thus leading to more nature-viewing opportunities. This report demonstrates how nonmarket valuation models can be used in targeting conservation programs such as the CRP.Environmental Economics and Policy,

Alternative Soil Fertility Management Options in Malawi - An Economic Analysis

In this paper, we analyze the factors that influence the productivity of maize among smallholder farmers, given that unfavourable output and input market conditions throughout the 1990s have compelled smallholder farmers into unsustainable agricultural intensification. We use farm-household survey data in order to compare the productivity of smallholder maize production under integrated (ISFM) and chemical-based soil fertility management using a normalized translog yield response model. The results indicate higher maize yield responses for integrated soil fertility management options after controlling for the intensity of fertilizer application, labour intensity, seed rate, land husbandry practices as well as selected policy factors. The estimated model is highly consistent with theoretical conditions. Thus we conclude that the use of ISFM improves maize productivity, compared to the use of inorganic fertilizer only. Since most farmers in the maize-based farming systems are crowded out of the agricultural input market and can hardly afford optimal quantities of inorganic fertilizer, enhancement of ISFM is likely to increase their maize productivity. We finally highlight areas of policy support needed to enhance ISFM uptake in smallholder maize-based farming systems.Malawi, smallholder agriculture, soil fertility management, yield response model, Livestock Production/Industries,

Alternative Soil Fertility Management Options in Malawi An Economic Analysis

In this paper, we analyze the factors that influence t he productivity of maize among smallholder farmers, given that unfavourable output and input market conditions throughout the 1990s have compelled smallholder farmers into unsustainable agricultural intensification. We use farm-household survey data in order to compare the productivity of smallholder maize production under integrated (ISFM) and chemicalbased soil fertility management using a normalized translog yield response model. The results indicate higher maize yield responses for integrated soil fertility management options after controlling for the intensity of fertilizer application, labour intensity, seed rate as well as land husbandry practices a s well as selected policy factors. The estimated model is highly consistent with theoretical conditions. Thus we conclude that the use of ISFM improves maize productivity, compared to the use of inorganic fertilizer only. Since most farmers in the maize-based farming systems are crowded out of the agricultural input market and can hardly afford optimal quantities of inorganic fertilizer, enhancement of ISFM is likely to increase their maize productivity. We finally highlight areas of policy support needed to enhance ISFM uptake in smallholder maize-based farming systems.smallholder agriculture, yield response model, soil fertility management, Malawi, Land Economics/Use,

Understanding Structure and Function in Semiarid Ecosystems: Implications for Terrestrial Carbon Dynamics in Drylands

This study advances understanding of how the changes in ecosystem structure and function associated with woody shrub encroachment in semi-arid grasslands alter ecosystem carbon (C) dynamics. In terms of both magnitude and dynamism, dryland ecosystems represent a major component of the global C cycle. Woody shrub encroachment is a widespread phenomenon globally, which is known to substantially alter ecosystem structure and function, with resultant impacts on C dynamics. A series of focal sites were studied at the Sevilleta National Wildlife Refuge in central New Mexico, USA. A space-for-time analogue was used to identify how landscape structure and function change at four stages over a grassland to shrubland transition. The research had three key threads: 1. Soil-associated carbon: Stocks of organic and inorganic C in the near-surface soil, and the redistribution of these C stocks by erosion during high-intensity rainfall events were quantified using hillslope-scale monitoring plots. Coarse (>2 mm) clasts were found to account for a substantial proportion of the organic and inorganic C in these calcareous soils, and the erosional effluxes of both inorganic and organic C increased substantially across the vegetation ecotone. Eroded sediment was found to be significantly enriched in organic C relative to the contributing soil with systematic changes in OC enrichment across the vegetation transition. The OC enrichment dynamics observed were inconsistent with existing understanding (derived largely from reductionist, laboratory-based experiments) that OC enrichment is largely insignificant in the erosional redistribution of C. 2. Plant biomass: Cutting-edge proximal remote sensing approaches, using a remotely piloted lightweight multirotor drone combined with structure-from-motion (SfM) photogrammetry were developed and used to quantify biomass carbon stocks at the focal field sites. In such spatially heterogeneous and temporally dynamic ecosystems existing measurement techniques (e.g. on-the-ground observations or satellite- or aircraft-based remote sensing) struggle to capture the complexity of fine-grained vegetation structure, which is crucial for accurately estimating biomass. The data products available from the novel SfM approach developed for this research quantified plants just 15 mm high, achieving a fidelity nearly two orders of magnitude finer than previous implementations of the method. The approach developed here will revolutionise the study of biomass dynamics in short-sward ecogeomorphic systems. 3. Ecohydrological modelling: Understanding the effects of water-mediated degradation processes on ecosystem carbon dynamics over greater than observable spatio-temporal scales is complicated by significant scale-dependencies and thus requires detailed mechanistic understanding. A process-based, spatially-explicit ecohydrological modelling approach (MAHLERAN - Model for Assessing Hillslope to Landscape Erosion, Runoff and Nutrients) was therefore comprehensively evaluated against a large assemblage of rainfall runoff events. This evaluation highlighted both areas of strength in the current model structure, and also areas of weakness for further development. The research has improved understanding of ecosystem degradation processes in semi-arid rangelands, and demonstrates that woody shrub encroachment may lead to a long-term reduction in ecosystem C storage, which is contrary to the widely promulgated view that woody shrub encroachment increases C storage in terrestrial ecosystems.NERC Doctoral Training Grant (NE/K500902/1)NSF Long Term Ecological Research Program at the Sevilleta National Wildlife Refuge (DEB-1232294