Utilizing and conserving agrobiodiversity in agricultural landscapes

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Abstract

A biodiversity-based paradigm for sustainable agriculture is a potential solution for many of the problems associated with intensive, high input agriculture, and for greater resilience to the environmental and socioeconomic risks that may occur in the uncertain future. The challenge is to understand the combined ecological and social functions of agrobiodiversity, determine its contribution to ecosystem goods and services and value for society at large, and evaluate options for the sustainable use and conservation of biodiversity across the agricultural landscape. Agrobiodiversity is most likely to enhance agroecosystem functioning when assemblages of species are added whose presence results in unique or complementary effects on ecosystem functioning, e.g., by planting genotypes with genes for higher yield or pest resistance, mixing specific genotypes of crops, or including functional groups that increase nutrient inputs and cycling. Simply adding more species to most agroecosystems may have little effect on function, given the redundancy in many groups, especially for soil organisms. The adoption of biodiversity-based practices for agriculture, however, is only partially based on the provision of ecosystem goods and services, since individual farmers typically react to the private use value of biodiversity, not the ‘external’ benefits of conservation that accrue to the wider society. Evaluating the actual value associated with goods and services provided by agrobiodiversity requires better communication between ecologists and economists, and the realization of the consequences of either overrating its value based on ‘received wisdom’ about potential services, or underrating it by only acknowledging its future option or quasi-option value. Partnerships between researchers, farmers, and other stakeholders to integrate ecological and socioeconomic research help evaluate ecosystem services, the tradeoffs of different management scenarios, and the potential for recognition or rewards for provision of ecosystem services. This paper considers ways that scientists from different disciplines can collaborate to determine the functions and value of agrobiodiversity for agricultural production, but within the context of understanding how biodiversity can be conserved in landscape mosaics that contain mixtures of land use types.

Introduction

Recent increases in agricultural productivity can largely be attributed to dependence on high-yielding varieties, irrigation, and agrochemical inputs, yet many of the inputs and practices of intensive agriculture are detrimental to human health, environmental quality, and the maintenance of biodiversity (Conway, 1997, Evenson and Gollen, 2003, MEA, 2005, Mooney et al., 2005). As people confront population growth, increased food demand, climate change, and the globalization of agricultural markets during the next few decades, agricultural landscapes will undergo unprecedented transitions. Most (75%) of the world's poor people live in rural landscapes, and are especially vulnerable to the ecological and economic risks associated with such transitions (WRI, 2005).

New solutions are necessary for producing more food and fiber, protecting the resource base upon which agriculture depends, and promoting social well-being (MEA, 2005). Conservation of existing biodiversity in agricultural landscapes and the adoption of biodiversity-based practices have been proposed as ways of improving the sustainability of agricultural production through greater reliance on ecological goods and services, with less damaging effects on environmental quality and biodiversity (Collins and Qualset, 1999, McNeely and Scherr, 2003, MEA, 2005). For example, in the Millennium Ecosystem Assessment (MEA, 2005), biodiversity is viewed as an important coping strategy against agricultural risks in an uncertain future, but with the current state of knowledge, this may be viewed as ‘received wisdom’ rather than substantiated proof of process (Wood and Lenné, 2005).

Evaluating the potential for the utilization and conservation of biodiversity in agricultural landscapes requires new types of communication and cooperation, e.g., among agriculturalists, ecologists, and economists to identify and establish adequate assessment strategies (Robertson and Swinton, 2005), between anthropologists and ecologists to preserve ethnobiological species and functions (Brush, 2004), and between conservation biologists and agriculturalists to seek common ground for managing genetic, species and ecosystem diversity in agricultural landscapes (Banks, 2004). Bridging the natural and the social sciences also creates frameworks that engage farmers and other stakeholders in the search for biodiversity-based solutions for increasing agricultural production in a sustainable manner (Pretty and Smith, 2004). However, much still needs to be learned about biodiversity as natural capital for providing ecosystem goods and services for agriculture, the direct and indirect use value in economic terms that are derived from these goods and services, and the social forces that will promote or impede its sustained adoption (Daily, 1997, Swift et al., 2004, Wood and Lenné, 2005).

This paper focuses on determining the links between agrobiodiversity and ecosystem (or environmental) goods and services, their net benefits, and scenarios that promote sustainable agriculture. The main focus is agrobiodiversity for agricultural production, but within the context of understanding how biodiversity can be conserved in landscape mosaics that contain mixtures of land use types, e.g., that range from production agriculture to extraction of products from wildlands, as well as urbanized or later successional natural areas. It considers ways that scientists from different disciplines can collaborate to determine the functions and value of agrobiodiversity, and the involvement of farmers and stakeholders in this complex process.

Section snippets

Defining agrobiodiversity

In this paper, agrobiodiversity refers to the variety and variability of living organisms that contribute to food and agriculture in the broadest sense, and the knowledge associated with them (Qualset et al., 1995). Sometimes agrobiodiversity is considered to encompass a broader definition, to include the full diversity of organisms living in agricultural landscapes, including biota for which function, in the human utilitarian point of view, is still unknown. Under this definition, planned

Rapid change in agricultural landscapes

At present, 10% of the global land area is under modern, intensive agricultural use, 17% is under extensive use associated with the use of far fewer artificial inputs, and 40% is grazed by domestic livestock (Wood et al., 2000, Mooney et al., 2005). The world's population of 6.3 billion people is projected to grow to 7.2 billion by the year 2015, 8.3 billion by 2030 and to 9.3 billion by 2050 (FAO, 2003). By 2050, food production must double to meet human needs. In order to meet this increasing

Agrobiodiversity during agricultural transitions

Worldwide, many agricultural landscapes have already experienced some level of transition towards intensive agriculture, i.e., with high application of inputs based on non-renewable resources, substitution of human labor by machines and fossil fuels, and high capital invested per unit of land (Matson et al., 1997). In many areas where traditional farming systems still exist, mixed practices often co-exist with some use of fertilizers or mechanization combined with continued use of traditional

Understanding the functions of agrobiodiversity

In examining roles for agrobiodiversity as a contributing force to sustainable agriculture, understanding its functions becomes a high priority. Agrobiodiversity is most likely to enhance ecosystem functioning when a unique or complementary effect is added to an ecosystem, e.g., by planting genotypes with specific genes for higher yield or pest resistance (Qualset and Shands, 2005), mixing specific genotypes of crops (Zhu et al., 2000), using cover crops (Jackson et al., 2004) or intercropping (

Ecosystem services provided by agrobiodiversity

With the recent publication of the Millennium Ecosystem Assessment (MEA, 2005), great optimism has been placed on the potential for biodiversity to supply ecosystem services, i.e., biophysical functions and ecological processes that support human life and welfare:

“…where agriculture already dominates landscapes, the maintenance of biodiversity within these areas is an important component of total biodiversity conservation efforts, and, if managed appropriately, can also contribute to

Agrobiodiversity utilization and conservation: the human dimension

An array of issues for agrobiodiversity research has been described above, and the emphasis has been on moving toward sustainability through interdisciplinary research between biophysical and social sciences. This fits within the concept of integrated natural resource management (iNRM), which invokes an approach that examines tradeoffs between enhanced productivity, human well-being, and ecosystem resilience (Tomich et al., 2004, Tomich et al., 2007, Sayer and Campbell, 2003). Partnerships and

Conclusions

This paper has emphasized the need for more research on agrobiodiversity and its ecosystem services, both to justify agrobiodiversity conservation in traditional agricultural systems, and as a potential source of innovation for sustainable agriculture. Although a growing number of ecologists, economists, and NGOs are making the case that conservation measures for agrobiodiversity must be deployed immediately, precisely because of the current lack of scientific understanding of the totality of

Acknowledgments

We are especially appreciative of advice and comments from Sara Scherr, and also for input from Lijbert Brussaard, George Brown and Meine van Noordwijk. Funding is gratefully acknowledged from USDA CSREES OERI grant 2004-05207 and from a programmatic initiative from the College of Agricultural and Environmental Sciences at University of California at Davis.

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    From the symposium on: ‘Biodiversity in Agricultural Landscapes: Saving Natural Capital Without Losing Interest’ First DIVERSITAS International Conference on Biodiversity “Integrating biodiversity science for human well-being”, 11 November 2005, Oaxaca, Mexico.

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