Forest Structure and Species Composition of Limestone Forest after Mining , Phrae Province

Abstract

This study aimed to clarify the forest structure, species composition and the environmental factors to determine tree distribution in limestone forest after mining, Phrae Province. We established transect plots at three different forest sites including limestone forest (LSF), mixed deciduous forest with limestone forest (MDL) and abandoned mining limestone (AML). The transect plots were set up along an estribaciones to hilltop gradient by quadrat size 10 m x 10 m, at least 25 plots per stands. All trees in 10 m x 10 m were measured and identified, while, saplings and seedlings in subquadrat of 4 m x 4 m were identified and recorded during January to December 2016. In addition, the environmental factors in each 10 m x 10 m were also recorded.  The ordination analysis based on canonical correspondence analysis (CCA) was used to detect the determine factors of tree distribution.

The results showed that 68 species 52 genera and 31 families were found. Tree species, such as Parishia insignis Meliosma pinnata and Ficus macleilandii within the limestone forest, The MDL showed the highest density (444.44 stem ha^-1), the highest basal area (9.05 m²·ha^-1), and the highest species diversity (H') was 3.17 in tree habit, While, the shrub habit in LSF showed the highest density (578.38 stem·ha^-1).The CCA ordination presented the LSF was positively relative with soil moisture and rocky outcrop, The AML was positively relative with Soil bulk density. Furthermore, the environmental factors showed less effect to the MDL. The results suggest the effect of mining destroyed vegetation structure and environments especially soil bulk density. Hence, restoration of the limestone forest after mining is depends on species which can establish in unsuitable environments.