Species diversity, regeneration status and edaphic characteristics in Sabaiya collaborative forest, Nepal

Background/Question/Methods

Sabaiya collaborative forest (total area 3138.51ha) is one of the first pilot schemes approved by Ministry of Forest and soil conservation (MFSC), Nepal in 2004 which has started implementing its scheme. This is a Sal ( Shorea robusta Gaertn. F) forest situated in the plains of Nepal. To assess the status of diversity and regeneration of this pilot scheme phytosociological study of the forest was carried out and species diversity, importance value index, basal area, density & regeneration status were accessed. Two belt transects each of 2 km long were laid for the study. Each transect contained 10 quadrats of 10x10m. Edaphic charecteristics were also studied. Study was conducted in December 2010. Annual fire episodes and anthropogenic pressure wass clearly visible in this forest.

Results/Conclusions

A total of 51 species were recorded in the study, of which 15 were represented in tree group, 20 in the shrub group and 9 in the herb group. Both seedling and sapling were represented by 11 species each. The forest was dominated by Shorea robusta (68.8%) and Mallotus phillipensis(6.8%). Occasionally Terminalia tomentosa (4%) and Syzygium cumini (4.8%) were present in the canopy. The sub-canopy was dominated by Lagerstroemia parviflora and Semecarpus anacardium. The understory was quite sparse and dominated by Shorea robusta and Daubanga grandiflora seedlings; and shrubs such as Clerodendron infortunatum and Eupatorium oderatum . Among herbs Cyperus iria and Cynadon dactylon were dominant. Despite having satisfactory regeneration of seedlings of Sal (16960 stem/ha), very few  (120 stem/ha)  saplings were recorded. Similar was the case with other tree species. Each year occuring mild fire enriched the soil but it also destroyed the delicate saplings and seedlings. Heavy dependence of the adjacent community for their subsistence needs has also interfared with the regeneration. The study of edaphic charecteristics  revealed that soil was sandy loam to loamy sand, slightly acidic to near neutral ( pH 5.34-6.88), soil Nitrogen moderate (0.12-0.25%) & Organic carbon moderate (1.5-3.0%).