We examined the relationships between leaf damage caused by insects and pathogens and three leaf traits (leaf toughness, total phenol contents, and nitrogen contents) of five dipterocarp species in a lowland rain forest in peninsular Malaysia. The measurements were made on all leaves of 9- month-old dipterocarp seedlings that emerged at mast fruiting in September 1996. Means of leaf damage levels were significantly different among the species. Percentages of heavily damaged leaves (damaged leaf area> 50%) varied from 5.0% in Shorea multiflora to 13.8% in S. pauciflora. Mean leaf damage levels were not correlated with the three leaf traits across species, but percentages of heavily damaged leaves showed a significant negative correlation with the total phenol contentsi n in leaves. This result suggests that phenolics may not necessarily reduce the average amounts of leaf damage, but may suppress heavy leaf feeding by herbivores.

View full abstract

The objective of this study was to evaluate the soil quality of a small inland valley watershed in the Sahel zone of Niger, West Africa. The physical, biological, and chemical properties of the soil were characterized. Longitudinal and transverse sections of two transect lines were surveyed in the benchmark Matankari watershed (BMW). Soil samples were taken along these transect lines. The BMW consists of four geographical units: plateau, slope, plain, and basin. The plateau is made up of tertiary muddy sand stone (TMSS), while the slope is made up of sand cover. The basin is a unique site holding runoff water and eroded materials that accumulate from the upper geographical units. The analytical results revealed that the physical, biological, and chemical fertility parameters of the soils along the longitudinal transect line are quite low, as this is the section across the bottom of the BMW where a wadi is present. The soil fertility properties along the transverse transect line are better than along the longitudinal transect line. However, the soil fertility of all sites on the plain is quite low due to the high percentage of sand (>95%). The soils on the plateau and basin in particular have much better fertility properties than other sites because these soils have a high percentage of clay as well as high TC and TN content, indicating that there is some organic matter accumulation in these soils. Therefore, these geographical units in particular are not only suitable for cultivation, but they also may contribute to reduce the adverse effect on the soil and the environment with the proper application of ecologically adaptive technology. In the long run, this study can provide basic information regarding indigenous knowledge of the BMW, including ethnopedology and ethnobotany, to promote the development of such ecotechnology for sustainable agriculture in this region.

View full abstract

The objective of this study is to evaluate an indigenous knowledge of the soil in conformation with scientific data. A benchmark watershed was selected near Matankari village, Dosso City in the Sahel zone of Niger, West Africa, and the indigenous soil classification system was surveyed at the benchmark Matankari watershed (BMW). It was revealed that the farmers in BMW used the factors of soil color, soil texture, and soil fertility level to evaluate the soil. Each factor was divided into 3 to 4 subdivisions, the headings for which were given in the local language in Haussa. The farmers identified the soil by a combination of these subdivisions or by the direct meaning of the subdivision. “Hori-rairay”, “Lesso”, “Phara-kassa”, “Ja-kassa”, “Baka-kassa”, “Baringo”, “Ja-laka”, “Kounkou”, “Tsagana” are the various names assigned to the soil in BMW. The soil evaluations on color, texture and fertility are based on their long term experiences over the years, and are of considerable significance to their society. The soil samples which were collected from BMW, were subjected for quantitative evaluation and identification of soil property characteristics. Munsell's soil color, particle size distribution, total carbon, total nitrogen, available phosphorous, and effective cation exchangeable capacity were analyzed in the laboratory. The information derived from the farmers’ evaluation was well corresponded to the analytical data, for example, “Hori-rairay” which was evaluated as the poorest soil by farmers, was of light color, quite sandy, and had a lower fertility level than any other soil. On the other hand, “Baringo”, which was evaluated as the most fertile soil for crop cultivation in BMW, was of darker color, clayey, and had high effective cation exchange capacity. These quantitative characterizations revealed that the indigenous soil classification and evaluation system has a reasonable back ground, even empirical basis, which can be corroborated scientifically.
This study indicates that indigenous soil knowledge, in accordance with its scientific translation, can be a relevant source of information for effective practical application to the system of soil classification and evaluation. In addition, findings of this study suggests that indigenous soil knowledge may provide a rapid evaluation on microscale soil distribution in the fragile ecosystem of a semi-arid zone. In the long run, indigenous knowledge will playa vital role for sustainable agriculture in this region.

View full abstract

Mineral element accumulations in soils and trees in hill evergreen forest were studied at the Kog-Ma watershed research area, Doi Suthep - Doi Pui National Park, Chiang Mai, Thailand. Soil samples were collected in December 1996 and leaves, barks and wood samples from 28 tree species were collected during August and September 1995. The concentration of elements, C, N, P, K, Ca, Mg, Fe, Mn, Sand Na were analyzed and the accumulation amount in soils and trees was estimated. The element concentrations in soils were high in the surface, decreased towards deeper horizons and seemed to reach a constant level at a certain soil depth. The concentrations in soils were highest in the lower slope followed by the middle and upper slope. The accumulation of elements up to 1 m soil depth were also larger in the lower slope. The accumulations in trees were the largest in the trees growing on the lower slope. The woods accumulated larger amounts of elements than leaves and the emergent layers larger amounts than continuos canopy and undergrowth layer. The accumulation amounts of C, N, K, Ca, Mg, Fe, Mn and Na in soils for 1 m depth were estimated as 211000, 15400, 535, 272, 114, 1.69, 4.53 and 149 kglha/m, while in trees, 90400, 451, 508, 69.4,1.14,5.45 and 3.92 kg/ha, respectively.

View full abstract

The elements concentrations in tree species of hill evergreen forest were studied at the Kog-Ma watershed research area, northern Thailand. During August and September 1995, 514 samples of leaves, barks and woods were collected from 28 tree species and analyzed for C, N, P, K, Ca, Mg, Fe, Mn, B, Na and AI. In the present study we focused on the distribution pattern of the element concentrations in different compartments of different plant species, tree layers, and localities. The C concentrations were similar among species, compartments, strata (layer) and slope positions. N was found significantly higher concentrations in several species of Leguminosae. Castanopsis acuminatissima, Castano psis echinocarpa and Castano psis ferox exhibited characteristics as a generalist for various elements. Aporusa villosa seemed to accumulate P, Mg, Mn and AI in leaves. Several species showed very low element concentrations for certain elements, i.e., Eugenia oblata for Fe and Mn, Mammea harmandii for Fe, Mn and Na, and Quercus kingiana for Fe and Na. No significant deviation was found for the difference in strata. The concentrations of Ca, Mg and Na were the highest for trees in the lower slope. The elements P and K showed an opposite tendency. Leaves showed higher concentrations ofN, K, Ca, Mg, Fe, Mn, Al and Na than barks and woods.

View full abstract

Stabilization of farmers' land uses with perennial crops is an urgent policy issue for sustainable forest resource management in the tropical region. However, farmers' behavior is affected by natural resource conditions and the socio-economic environment of their living sphere. This article aims to illuminate characteristics of a commercialized farming system practiced by forest-border communities and issues on intensification of their land uses with a case study from West Sumatra, Indonesia.
Minangkabau farmers have long cultivated rice fields on flat land for subsistence, and recently dry land on mountain slopes for income. They plant the dry land with popular cash crops such as rubber, coffee, and cinnamon which have been introduced since the Dutch period. However, their dry land cultivation is hindered by many technical limitations, including soil degradation, poor seedling availability, and pests, although they could get over some of these problems with their own ideas. What is more burdensome is socio-economic constraints which small farmers can rarely overcome. Farmers have to invest much capital and labor in land preparation and planting, protection, and harvest of crops. However, they find it more difficult to work on their dry land in distant forests, compelled to concentrate more on cultivation of segmented and dispersed rice fields for their subsistence. Exacerbated by marketing fluctuations, small farmers with no production resources often give up growing cash crops, leaving their dry land uncultivated. Their idle dry land is too degraded to cultivate again without enough capital and labor. Farmers hesitate to fully introduce fruit trees and other perennials, afraid of cropping and marketing failure, and still rely on precarious frontier agriculture with the existing cash crops.
Viable methods of land use intensification must be explored to adapt commercialized farming to local ecological and economic conditions through examination of various farming systems in other parts of Sumatra.

View full abstract