0055-B5

Sustainable development through a complex agroforestry system in Indonesia

Eulis Retnowati 1


Abstract

Many different sustainable management systems have been put forward as viable solutions that will take the pressure off tropical forests. One of the more useful systems is "complex agroforestry". Complex agroforestry provides a land-management system that increases production and ecological stability, as well as supporting sustainable development. Complex agroforestry encourages the sustainable development of degraded lands by maintaining human activity, while conserving natural resources. Through its combined economic, environmental and social functions, complex agroforestry can make a significant contribution to sustainable development. It is its emphasis on management, economic and environmental qualities that distinguishes complex agroforestry from simple agroforestry systems, such as alley cropping, intercropping or hedgerow systems. One example of complex agroforestry is `damar' (Shorea javanica), which can provide annual farm income ranging between Rp1.65 million during the non-fruiting season through to Rp3.84 million in the fruiting season (US$1 = Rp8187). Vegetation analysis and fauna observation in mature damar agroforest with age ranges of between 39 and 41 years found 60 tree species, 12 mammal species, nine bird species, and two reptile species. Complex agroforestry also has the potential to significantly reduce atmospheric concentration of CO2 and mitigate climate change, with the total carbon fixed by damar agroforest at 287.9 t C/ha. Except for base saturation and pH value, soil conditions in mature damar agroforests are not statistically different from those in old secondary forests, and water debit fluctuations between the rainy and dry seasons do not differ greatly. Damar agroforest has made substantial progress in supporting local and surrounding populations as well as the environment through reducing poverty, increasing incomes, creating jobs, increasing food production and preserving and managing natural resources.


I. Introduction

Forest does not only support life system, but also generate it. Tropical rainforest produces wood for commercial timber and fuel wood, non timber forest products (such as medicine, ornamental plants, wildlife, row materials, rattan, bamboo, etc), and they also protect soil, retain moisture, and offer some environmental services as benefits such as hydrologic water cycle, soil erosion and carbon sequestration.

To avoid deeper pressure of tropical forest, the various aspect of sustainable management may be applied as the solution. Complex Agroforestry as a technique is considered as a sustainable management system for land that increases production and ecological stability and supports the sustainable development. This system can assist in a variety of short, medium and long term benefits both for local farmers and government. This system provides cash income to the farmers and a diverse range of product. The environmental benefit of the agroforestry are the protection of soils and water resources, micro climate, sequestration of carbon, and the high degree of spontaneous regeneration which allow conservation of a proportion of the original forest biodiversity.

Complex agroforestry is defined as forest structures planted and managed by farmers for the production of various forest and agricultural products on the same piece of land (de Foresta and Michon, l996). Complex agroforestry systems in intimately association with a high number of components (trees as well as treeless, lianas, herbs), and the physiognomy as well as functioning close to those observed for natural ecosystems, either primary or secondary forests are able to sustain both biodiversity conservation and farmers' economic needs (de Foresta and Michon, l994).

Complex agroforestry is different from simple agroforestry system such as alley cropping, intercropping or hedgerow systems due to its concept, management, and economic and environmental qualities. This system defined as agro-forest, seem to concern more forestry scientists rather than agriculturists.

This paper evaluates the potentials of complex agroforest of Damar Mata Kucing (Shorea javanica) in Lampung Indonesia as a sustainable land use management in supporting sustainable development.

II. Methods

The study was conducted in Krui, West Lampung district, Lampung Province, Sumatra, Indonesia. The coordinates of West Lampung district are 103º30' to 105º E longitude and 4º30' to 6º S latitude. The study site is classified as strongly dissected mountains, steep to very steep slope (30%-75%) with a soil order of mostly inceptisols (Center for Soil Research, l989). The elevation of the study site range from 100 m to 600 m above sea level (asl), the annual average of rainfall is 3518.3 mm/year, with 9 months greater than 100 mm (wet months), and the rainy days is 145 days/year. Mean annual minimum temperature and mean annual maximum temperature are 21.2ºC and 33.2ºC respectively.

The study focused on agroforests belonging to farmers living in or originally from Pesisir Tengah sub-district. The study was done based on the direct observation (primary data) and the indirect observation (secondary data). Data collection included the number of trees, tree height, diameter at breast height, micro climate, the number of fauna species, production of damar resin and other non wood, etc.

The carbon monitoring system used in this study was developed by Winrock International's Carbon Monitoring Program to quantify the amount of C in land use systems using forest and agroforestry inventory principles and practices (MacDicken, l997). Winrock's system quantifies C sequestered by measuring changes in four main carbon pools are above-ground biomass, litter, herbaceous material and soil.

To estimate biomass (kg) of above-ground vegetation, the following general biomass regression equation was used for most species: exp{-2.134+2.530 x ln(DBH)} (Brown, l997). Root biomas was estimated by taking 25 % of above-ground biomas (Cairns et al., l997).

III. Results and Discussion

A complex agroforestry system called damar agroforest has been practiced by local people in Krui (the Pesisir areas), Lampung Province, Indonesia, since the second half of 19 century (Rappard l937, in Michon and de Foresta, l995). The resin-producing tree called damar (Shorea javanica) that dominates its vegetation structure is a species belongs to the Dipterocarpaceae. Recently, the satellite image indicates that there are approximately 55,000 ha of this nature agroforest in Krui. This system has given significant role to the farmer, the community and the country economically, environmentally, and socially.

1. Economic Functions

Economically, complex agroforests provide farmers with marketable and sustainable high value product such as resin, fire wood, fruits, animal fodder, medicines, and high-grade timber. All of these product give sustainable income to the farmer (directly) and sustainable benefit to the country (indirectly). Through complex agroforestry the farmers will have the option which offer the potential to diversify their businesses. This is achieved through the integration production systems which can offer a number of advantages when compared to traditional monoculture forestry planting.

Damar agroforest as an example of complex agroforest system provide wide range of source of income to the farmers, their neighborhood and the actors along trading chain. Damar trees provide regular cash income from the harvesting and sale of damar resin. The damar produced by S.javanica is called damar mata kucing (cat-eye damar).

In Pesisir Krui areas, damar resin from damar agroforest has an important contribution to the farmers' income. According to Dupain, (l994) (in de Foresta and Michon, l995), damar resin trade in the Pesisir areas involved Rp 14.5 billion (US $ 6.6 million) in l993, of which Rp 6.5 billion was the gross income of the farmers. Meanwhile de Foresta and Michon (l997) reported that mature damar agroforest provides annual farm income ranging between Rp 1.65 million (no fruiting season) and Rp 3.84 million (in fruiting season) in Pahmungan Village of Pesisir area.

Damar for international trade come from South East Asia region, mainly Indonesia (Coppen, l995). Damar resin from Pesisir Krui areas contribute about 80% of national total production. The main use of the damar resin is in the manufacture of paper, wood varnishes and lacquers, and some paints.

Damar trees were usually first tapped from 20-25 years of age, or if tree diameter reach > 25 cm. The yield of damar resin per tree in Panengahan village (166 g/tree/month-905 g/tree/month) is lower than in Pahmongan village (1,500 g/tree/month). Types of damar agroforest, stages, elevation, total-tree-species density, tapped-damar-tree density, and soil conditions are the potential factors affecting the yield of damar resin. Low yields of damar resin could be also caused by minimal cultural treatment applied to damar trees and their site. Special treatments might be needed, such as fertilization and intensive cleaning, particularly until the trees reach about 30 years (Sukandi, l997). Recent price of damar resin is Rp 4000,- or US $ 0.5 per kg (on farm). In order to get additional value, the farmers should have post harvest technology, so that the price will increase.

Table 1. Mean production of damar (S.javanica) resin (per tree per month) in Krui

Two major commercial fruits in damar agroforest, durian (Durio zibethinus Murr.) and duku (Lansium domesticum), are sold in urban markets. Durian has become more marketable at a good price since the l980s, when access to Krui from outside West Lampung district was improved (Sukandi, 1997). Other crops, such as coffee and pepper, can also be managed for income before the tree component products can be tapped or harvested (de Foresta and Michon, l994).

2. Environmental Functions

Complex agroforests system afford environmental benefit. They improve soil fertility by fixing nitrogen from the air and recycling nutrient from the soil, hold moisture, reduce soil erosion, keep valuable topsoil in place, reduce the intensity of downstream flooding and maintain watershed function, and increase biodiversity of degraded lands.

Vegetation analysis in mature damar agroforest in Krui recorded 60 trees species on systematic strips plots of 20 x 20 m (the total plot area is 17 ha). The standing stock of all species with trunk diameter of > 20cm, > 50cm, > 60 cm (clear bole height) were 140.49 m³/ha, 78.90 m³/ha, 59.53 m³/ha respectively (Heriyanto et al, 2001). Meanwhile Wijayanto (l993) recorded 39 species (trees over 20 cm in diameter, on 75 randomly plots of 20 x 20 m) with, mean density 245 trees and mean basal area of 33 m² per hectare. This condition shows the close structural similarity between natural forest and mature damar agroforest managed by farmers.

Fauna observation in mature damar agroforest in Krui found 12 mammal species, 9 bird species and 2 reptil species. Meanwhile Sibuea and Herdimansyah (l993) recorded that the density of the primate population (macaques, leaf monkeys, gibbons, and siamang) in the agroforest are quite similar to those observed for natural forests. Almost all mammal forest species are present in damar agroforest (at least 46 mammal species including 17 species protected by Indonesian law).

Complex agroforest have high potential to reduce atmospheric concentration of CO2 and mitigate climate change. Complex agroforest could sequester C and could prevent further deforestasion by providing wide range of source of income. The result of this study show that the total carbon fixed by damar agroforest is 287,9 ton C/ha (Table 2).

Table 2. Carbon stock by component for mature damar agroforestry system in Krui, Lampung.

Aboveground biomass (tC/ha)

Litter (tC/ha)

Herbaceous material (t C/ha)

Soil (t C/ha)

Roots (t C/ha)

Total (t C/ha)

176.8

2.4

1.1

63.4

44.2

287.9

Mature damar agroforest contain higher stock of carbon than homegarden systems. This is due mainly to the presence of more trees in mature damar agroforest. Study in neighboring district of Pakuan Ratu (Roshetko et al., 2002) show that total C of homegardens ranged from 56 to 174 t C/ha (homegarden ages varied from 12 to 17 years).

Complex agroforest are dominated by trees. Ecologically, therefore complex agroforest might resemble old forests. The positive effect of the trees on micro climate in mature damar agroforest might be realized since the crowns of the trees have fully developed and the density of trees is relatively high. In this stage, the micro climate condition in a mature damar agroforest can reach those in an old forest (Table 3).

Table 3. The micro climate in mature damar agroforest

Location

Ta Max (º C)

Ta Min (º C)

Ts Max (ºC)

Ts Min (ºC)

07 am RH (%)

01 pm RH (%)

05 pm RH (%)

TESR (KJ/m² /day)

ISR Cal/cm² /men

Mature Damar Agroforest
Bare land

25.2
29.5

22.2
21.8

24.0
30.0

23.2
25.9

97
91

98
78

97
85

0
12,364

0
0.344

Where:

The soil conditions at different stages of damar agroforest are gradually improved. Beyond the age 29-31 years, damar agroforests might have positive effects on soil conditions. Except for base saturation and pH value, soil conditions in mature damar agroforests (39-41 years old) are not statistically different from those in old secondary forests. The value of base saturation and pH in mature damar agroforests are higher than those in old secondary forest (Sukandi, l997).

Another important function of complex agroforest is increasing the infiltration of rain water and recharges ground water, regulating the flow of streams and rivers. So that water debit fluctuation between rainy season and dry season is not significantly different like as in damar agroforest.

3. Social Functions

Complex agroforestry could improve the social welfare of the community by supporting the development of economic and natural resources. This system could provide valuable employment, business opportunities, and develop the village economy with environmental awareness. Through complex agroforest the people could earn sustainable income from varied product, and they will have a better chance acces to education, security, health care, and information.

Furthermore by meeting the need for subsistence and shorterm cash income, complex agroforestry system could reduce the pressure on the natural forests. Damar agroforest has made substantial progress in supporting local and surrounding populations as well as the environment through reducing poverty, increasing income, creating job, increasing food production, preserving and managing natural resources. This condition leads the population in West Lampung into good health condition, life expectancy, and education. Therefore, the community in West Lampung have been very dependent on the damar agroforest.

4. Sustainable Development

The contribution of complex agroforestry to the sustainable development is very significant through its economical, environmental, and social functions. Complex agroforest could meet the criteria of sustainable development including (1) not creating negatif impact to the environment, (2) improving forest hidrology functions, (3) improving biodiversity, (4) increasing food and wood productivity, (5) involving stakeholders, (6) appreciating customary right and local community, (7) increasing job opportunity.

The economic risk of complex agroforestry for the farmer is relatively low, as the need for short-term cash income, so that any pressure on forest land is reduced. Furthermore there is urgent need for intensive land use practice for maximizing output from limited land resources. Complex Agroforestry is considered to be a very important tool for maximizing output by integrating crops and trees. Therefore Agroforestry complex can encourages the sustainable development of degraded lands by maintaining human activity while conserving natural resources.

IV. Conclusion and Recommendation

The contribution of complex agroforestry system to the sustainable development is very significant through its economic, environmental, and social functions. Although complex agroforestry provides considerable socio-economic benefits, it also requires specific techniques and management. The importance of selecting appropriate tree species for the environment and the importance of initial care for the plants should be considered. The farmer's ability on the post harvest technology should be increased. The application of complex agroforestry system should be followed by developing both basic and advanced industries for handling the leading commodity within the area, regulating reasonable basic price rate for local commodity within the local producer level, building transportation capacity, developing market, and empowering the local people to be able to wisely use their natural resources.

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1 Forest and Nature Conservation Research and Development Centre, Jl. Gunung Batu 5, PO. Box 165, Bogor, Indonesia. eulisr@email.com