The Effects of Forest Restoration on the Species Diversity and Composition of a Bird Community in Northern Thailand

ABSTRACT: As tropical forests continue to be destroyed, restoration of forest ecosystems is becoming a high priority for biodiversity conservation. However, few studies have been carried out to determine the effects of forest restoration on biodiversity recovery. Therefore, this study was carried out to examine the effects of forest restoration on the species richness and composition of bird communities in northern Thailand. Bird surveys were carried out in framework species plantations, established by the Forest Restoration Research Unit (FORRU) at Ban Mae Sa Mai in Suthep-Pui National Park; 1200-1300 m above sea level, 18° 52´ N, 98° 51´ E. Framework tree species are chosen to be attractive to seed-dispersing wildlife such as birds or bats. Surveys were carried out over 1 year from June 2002-July 2003. Point counts and the Mackinnon List Method were used, to determine the species richness, diversity, abundance and density of birds in non-planted control plots and planted plots of different ages established in 1998, 2000 and 2002. In addition, observations of bird behavior in the planted trees were recorded.

Eighty-eight bird species were recorded from 57 genera and 30 families; 64 resident and 19 species of migratory birds. Three species of frugivorous bird and 15 species of omnivorous bird were recorded. Thirty-six birds species were observed in the non planted control plots and 68 species in planted plots; 43, 45 and 47 species in recently planted plots, 2-year-old and 4-year-old planted plots respectively. Bulbul species e.g. Red-whiskered Bulbul, Sooty-headed Bulbul and Flavescent Bulbul were the dominant species in the planted plots. Chestnut-capped Babbler, Red-whiskered Bulbul and Grey-breasted Prinia were the dominant species in the non-planted control plots. The Mackinnon List Method showed highest species richness of birds in 2-year-old planted plots, followed by the control plots, recently planted plots and lastly 4-year-old planted plots. The Point Count Method showed that planted plots had higher richness indices and diversity indices than non-planted control plots. Non-planted control plots had more even bird communities than the oldest (4-year-old) planted plots. Similarity indices showed that the oldest planted plots were most similar to medium-aged planted plots and were most different from recently planted plots. The population density of birds in the control plots was higher than in the planted plots. However, non-planted control plots had a higher population density of birds of open areas than planted plots did, whilst population densities of forest birds were higher in the planted plots. Birds used 41 woody plant species, of which 18 were food plants. The birds fed on fruits, flowers and nectar.

This study showed that planting framework tree species increased bird species richness (at the landscape level), and attracted several bird species which could disperse seeds into planted area and thus help to accelerate forest regeneration. In addition, tree-planting attracted progressively more forest birds as the plots matured. Fifty-four percent of bird species, recorded in planted plots, were the same as those in the nearest patch of remnant forest, Dong Seng community forest.