Agroforestry Models for Promoting Effective Risk Management and Building Sustainable Communities

Damasa B. Magcale-Macandog

Abstract Soil erosion and environmental degradation due to the cultivation of marginal upland areas are now considered major environmental risks in the Philippines. Agroforestry may help address the situation. In agroforestry systems, the positive interactions of tree-crop combinations not only improve biophysical conditions in farms, but also enhance food security in farming households.

A combination of Participatory Rural Appraisal (PRA), a household survey, focus group discussions, field experiments, and simulation modeling was undertaken in Claveria, Misamis Oriental, Philippines. The agroforestry system adopted depended on the farmers' motivations. The adoption of agroforestry significantly increased the households' level of income by around 42–137 %, compared with that from continuous annual mono-cropping. Another beneficial feature of an agroforestry system was the enhanced nutrient inflow to the system through leaf litterfall, stemflow, and throughfall. A modeling study using the WaNuLCAS model showed that the Eucalyptus-maize hedgerow system provided significant improvements to a range of biophysical and economic measures of productivity and sustainability.

It is recommended that both national and local government units mainstream their policies and efforts toward promoting agroforestry adoption in the Philippine uplands.

Keywords Agroforestry • Food security • Land degradation • Leaf litterfall • Nutrient inflow • Soil erosion

Introduction

The uplands in the Philippines are of great importance and interest because they comprise about 59 % of the country's total land area. They are dynamic and highly interactive landscape components of the rural system, and also serve as the life support for the lowlands and coastal areas. In addition, they are home to the increasing population of the “poorest of the poor,” and are expected to absorb more of the expanding population (Sajise and Ganapin 1991).

The Philippine uplands are a very heterogeneous and fragile resource base (Sajise and Ganapin 1991). Most of these areas are either open grassland, degraded, or occupied by settlers (Villancio et al. 2003). More than 20 million people are estimated to have settled in the uplands, and the number is increasing at a rate of about 2.8 % annually, which is above the national average of 2.32 %.

Its geographical location has made the Philippines highly vulnerable to natural hazards, the most common of which is the occurrence of turbulent typhoons. During the decade from 2001 to 2012, the country was hit by a total of 184 typhoons, or an average of 18 typhoons per year (Israel and Briones 2012). Climate change is perceived to have increased the frequency and intensity of heavy rainfall associated with typhoons and other weather systems, resulting in flooding. From 2000 to 2010, damage to agricultural crops caused by typhoons, floods, and droughts amounted to nearly PHP 106.88 million. Rice, corn, and other high value cash crops sustained the most damage. Typhoons Ondoy (Ketsana) and Pepeng (Parma) in September and October 2009 wrought havoc in both urban and rural areas in the country, with total damage reaching PHP 36.2 billion.

In the uplands, a major problem is food insecurity, which is mainly a consequence of land degradation. There is general recognition of the serious implications of deforestation, soil erosion, declining agricultural productivity, loss of biodiversity, off-site impacts, increasing poverty, and the social costs associated with the biophysical and ecological instability in the uplands. While 53 % of the Philippines' total land area is classified as forestlands, only 17 % is adequately covered with forest vegetation. In fact, the total forest cover in the country declined by as much as 3.54 % for the period 1990–1995, the fourth highest loss rate in the world. This rapid decline in forest areas can be attributed to the large and rapid conversion of the Philippine uplands into permanent annual cropping areas to meet the food requirements of an increasingly expanding population (Domingo and Buenaseda 2000). However, the productivity of sloping lands has been diminishing at an alarming rate due to soil degradation or erosion brought about by the activities of this population as it grows. According to Escaño and Tababa (1998), the rates of soil erosion in sloping areas range from 23 to 218 ton/ha/year for bare plots on gradients of 27–29 % to 36–200 ton/ha/year on plots cultivated up and down the hill. These rates are higher than the acceptable soil loss level of 3–10 ton/ha/year (Paningbatan 1989), and the situation poses a grave threat to the productivity and sustainability of farming in the upland areas.

In summary, the uplands can be characterized as degraded and ecologically marginal for agricultural purposes with landscapes that are highly sensitive and of low resilience. The biophysical limitations of these lands affect production, income, and household food security. Diminished food access due to the degraded natural resources, higher food prices, limited income opportunities, and the impact of natural elements leave the upland population a legacy of poverty and food insecurity.

Agroforestry is a dynamic, ecologically-based, natural resource management system that, through the integration of trees into farms, diversifies and sustains smallholder production for increased social, economic, and environmental benefits (Leaky 1996). Introducing trees within the cropping system can help prevent land degradation, increase biodiversity, and at the same time allow the continued use of the land for agricultural crop production (Wise and Cacho 2002).

Mature trees in agroforestry systems can yield numerous positive effects on cropped fields (Garcia-Barrios and Ong 2004). Among these are improved soil fertility and physical properties via organic matter addition from litter; reduced soil erosion through stabilization of loose soil surface by tree roots; recovery of leached nutrients from deep soil layers inaccessible to crops; reduced soil evaporation, leaf temperature, and evaporative demand by crops via tree shade; increased soil infiltration rate; protection against wind and runoff; reduced weed population; and reduction and potential slowdown of windborne pests and diseases. In a system where nitrogen (N)-fixing trees are used as hedgerows, alternative sources of N for trees can significantly reduce competition with crops.

 
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