Timothy S. Thomas

Determinants of Land Use in Amazônia: A Fine-Scale Spatial Analysis

Wetter areas of the Amazon basin exhibit lower rates of agricultural conversion. Previous analyses, using relatively aggregate data on land cover, have been unable to determine the extent to which this reflects limited access versus unfavorable agroclimatic conditions. This article uses census-tract level data for the Brazilian Amazon to relate forest conversion and pasture productivity to precipitation, soil quality, infrastructure and market access, proximity to past conversion, and protection status. The probability that land is used for agriculture or intensively stocked with cattle declines markedly with increasing rainfall, other things equal.

Geographic Patterns of Land Use and Land Intensity in the Brazilian Amazon

Using census data from the Censo Agropecuario 1995-96, the authors map indicators of current land use, and agricultural productivity across Brazils Legal Amazon, These data permit geographical resolution about ten times finer than afforded bymunicipiodata, used in previous studies. The authors focus on the extent, and productivity of pasture, the dominant land use in Amazonia today. Simple tabulations suggest that most agricultural land in Amazonia yields little private economic value. Nearly ninety percent of agricultural land is either devoted to pasture, or has been out of use for more than four years. About forty percent of the currently used pastureland, has a stocking ratio of less that 0.5 cattle per hectare. Tabulations also show a skewed distribution of land ownership: almost half of Amazonian farmland is located in the one percent of properties that contain more than two thousand hectares. Multivariate analyses relate forest conversion, and pasture productivity to precipitation, soil quality, infrastructure, and market access, proximity to past conversion, and protection status. The authors find precipitation to have a strong deterrent effect on agriculture. The probability that land is currently claimed, or used for agriculture, or intensively stocked with cattle, declines substantially with increasing precipitation levels, holding other factors (such as road access) constant. Proxies for land abandonment are also higher in high rainfall areas. Together these findings suggest that the wetter Western Amazon is inhospitable to exploitation for pasture, using current technologies. On the other hand, land conversion, and stocking rates are positively correlated with proximity to past clearing. This suggests that in the areas of active deforestation in eastern Amazonia, the frontier is not :hollow:, and land use intensifies over time. But this area remains a mosaic of lands with higher, and lower potential agricultural value.

Viable Reserve Networks Arise From Individual Landholder Responses To Conservation Incentives

Conservation in densely settled biodiversity hotspots often requires setting up reserve networks that maintain sufficient contiguous habitat to support viable species populations. Because it is difficult to secure landholder compliance with a tightly constrained reserve network design, attention has shifted to voluntary incentive mechanisms, such as purchase of conservation easements by reverse auction or through a fixed-price offer. These mechanisms carry potential advantages of transparency, simplicity, and low cost. However, uncoordinated individual response to these incentives has been assumed incompatible with the conservation goal of viability, which depends on contiguous habitat and biodiversity representation. We model such incentives for southern Bahia in the Brazilian Atlantic Forest, one of the biologically richest and most threatened global biodiversity hotspots. Here, forest cover is spatially autocorrelated and associated with depressed land values, a situation that may be characteristic of long- settled areas with forests fragmented by agriculture. We find that in this situation, a voluntary incentive system can yield a reserve network characterized by large, viable patches of contiguous forest, and representation of subregions with distinct vegetation types and biotic assemblages, without explicit planning for those outcomes.

Opportunity costs of conservation in a biodiversity hotspot: the case of southern Bahia

Biodiversity ‘hotspot’ areas, which are characterized by concentrations of endemic species and severe anthropogenic loss of natural habitat, might be thought to present steep opportunity costs for maintaining forest cover against pressures of agricultural conversion. We examine this proposition for the southern part of the state of Bahia, a center of endemism within the Brazilian Atlantic Forest, which has less than 8 per cent of its original primary forest cover remaining. Using data from a survey of property values, we relate land price to land characteristics, including land cover, soil quality, slope, climate, and road proximity. We find median land values of R

Quantifying the Rural-Urban Gradient in Latin America and the Caribbean

725/hectare, or about US

Creating markets for habitat conservation when habitats are heterogeneous

400/hectare at recently prevailing exchange rates. Remaining land under forest has a market value 70 per cent below comparable cleared land.

The economic and environmental impact of trade in forest reserve obligations: a simulation analysis of options for dealing with habitat heterogeneity

This paper addresses the deceptively simple question: What is the rural population of Latin America and the Caribbean (LAC)? It argues that rurality is a gradient, not a dichotomy, and nominates two dimensions to that gradient: population density and remoteness from large metropolitan areas. It uses geographically referenced population data (from the Gridded Population of the World, version 3) to tabulate the distribution of populations in Latin America and in individual countries by population density and by remoteness. It finds that the popular perception of Latin America as a 75 percent urban continent is misleading. Official census criteria, though inconsistent between countries, tend to classify asurbansmall settlements of less than 2,000 people. Many of these settlements are however embedded in an agriculturally based countryside. The paper finds that about 13 percent of Latin America populations live at ultra-low densities of less than 20 per square kilometer. Essentially these people are more than an hours distance from a large city, and more than half live more than four hoursdistance. A quarter of the population of Latin America is estimated to live at densities below 50, again essentially all of them more than an hours distance from a large city. Almost half (46 pecent) of Latin America live at population densities below 150 (a conventional threshold for urban areas), and more than 90 percent of this group is at least an hours distance from a city; about one-third of them (18 percent of the total) are more than four hours distance from a large city.

At loggerheads? Agricultural expansion, poverty reduction, and environment in the tropical forests

A tradable development rights (TDR) program focusing on biodiversity conservation faces a crucial problem defining which areas of habitat should be considered equivalent. Restricting the trading domain to a narrow area could boost the range of biodiversity conserved but could increase the opportunity cost of conservation. The issue is relevant to Brazil, where TDR-like programs are emerging. Current regulations require each rural property to maintain a forest reserve of at least 20 percent, but nascent policies allow some tradability of this obligation. The authors use a simple, spatially explicit model to simulate a hypothetical state-level program. They find that wider trading domains drastically reduce landholder costs of complying with this regulation and result in environmentally preferable landscapes.

Economics of adaptation to climate change : ecosystem services

A tradeable development rights (TDR) program focusing on biodiversity conservation faces a crucial problem: defining which areas of habitat should be considered equivalent. Restricting the trading scope to a narrow area could boost the range of biodiversity conserved but could increase the opportunity cost of conservation. The issue is relevant to Brazil, where TDR-like policies are emerging. Long-standing laws require each rural property to maintain a legal forest reserve (reserva legal) of at least 20%, but emerging policies allow some tradeability of this obligation. This paper uses a simple, spatially explicit model to simulate a hypothetical state-level program. We find that wider trading scopes drastically reduce landholder costs of complying with this regulation and result in environmentally preferable landscapes.....Programas que tenham por objetivo desenvolver um mercado de Direitos Especiais de Propriedade (DEP) enfrentam um problema fundamental, qual seja a definicao de areas de preservacao equivalentes. Caso a definicao seja por um conceito muito restritivo, podera ocorrer uma maior conservacao da biodiversidade, porem com um aumento do custo de oportunidade da preservacao ambiental. O assunto e relevante para o Brasil onde programas semelhantes aos DEP estao surgindo. A legislacao exige que cada propriedade rural mantenha pelo menos 20% de sua area na forma de florestas (reserva legal), porem algumas politicas nascentes ja permitem tipo de negociacao de Direitos. Este trabalho usa um modelo espacial simples para simular o efeito de um programa hipotetico implantado em um estado. O principal resultado e que uma politica menos restritiva para a comercializacao dos DEP reduz de forma expressiva, para os produtores rurais, os custos de cumprir a legislacao e leva a solucoes preferiveis sob o ponto de vista ambiental.