Diversity, structure and standing stock of wood in the homegardens of Kerala in peninsular India.
Kumar B. M., George S. J., Chinnamani S.
Author Affiliation: All India Co-ordinated Research Project on Agroforestry, College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur 680?654, India.
Agroforestry Systems 25 : 243-262
Abstract : A survey was conducted in 17 selected thaluks (revenue sub-divisions) of Kerala state to elucidate the floristic structure, composition and the extent of similarities and diversities in the composition of home gardens, with particular reference to small (0.4 ha), medium (0.4-2 ha) and large (>2.0 ha) holding size categories. The potential of the home gardens to supply commercial timber and fuelwood was also assessed. Some 252 farmers were selected through a stratified random process. In addition to gathering general information on crop and livestock production enterprises, all scattered trees and shrubs (?15 cm girth at breast height) on the homestead and border trees (except palms and rubber) were enumerated. There was tremendous variability both in the number of trees and shrubs present and species diversity of the selected homesteads in different provinces. All sized holdings also exhibited profound variability in the number of woody taxa and individuals present. In total, 127 woody species (girth at breast height (GBH)?15 cm) were encountered. The mean number of woody taxa found in the home gardens ranged from 11 to 39. Floristic diversity was higher in the smaller homesteads and decreased with increasing size of holding. Mean Simpson's diversity index for the homesteads ranged from 0.251 to 0.739, suggesting that floristic diversity was moderate to low (compared with a value of >0.90 for species-rich evergreen forests in the Western Ghats). Sorensen's similarity indexes suggested a moderately high degree of similarity for the different tree species found. No clear cut planting pattern was discernible in the home gardens. Trees and shrubs were either scattered throughout the homestead or on farm boundaries. Farmers tended to prefer timber trees such as ailanthus (Ailanthus triphysa, highest frequency) and teak (Tectona grandis), and fruit trees such as mango (Mangifera indica), jack (Artocarpus heterophyllus) and cashew (Anacardium occidentale). Major home garden species were represented in all diameter classes. The diameter structure, however, exhibited a slightly skewed (+) distribution pattern, having the highest frequency in the 20-30 cm classes, thus ensuring adequate regeneration status and making home gardens a sustainable as well as a dynamic land use system. Average commercial standing stock of commercial timber on homesteads ranged from 6.6 to 50.8 m³/ha and fuelwood volume was of the order of 23 to 86 m³/ha. Implicit in these high volumes is the fact that a substantial proportion of the society's wood demands are met from the homesteads. Palms, however, constituted the dominant component of both standing commercial timber and fuelwood volumes, accounting for as much as 63% and 72%, respectively, of the total wood in these categories.