Environmental Engineering Reference
Fig. 2 White oak regenerating forest site II in Indian central Himalaya. A - H represent girth
classes of individuals of the species in cm. A : seedlings, B : 10-30, C : 30.5-60, D : 60.5-90, E :
90.5-120, F : 120-150, G : 150.5-180 and H : >180
improves nutrient status of the habitat and makes gradual opening for its associates
from the adjacent forests.
Oak has comparatively higher demand for N than the pine (Singh and Singh
1992 ). In ridge area that was occupied by pine, the dynamic available N pool in the
soil at any point of time is very low and N immobilization by microbes in decom-
posing pine litter further increases the N shortage in the soil (Singh et al. 1984 ).
Because of this reason oak in general is not able to reoccupy the habitats in ridge
areas. However, the wash off of nutrients from the slopes that brings soil and nutrients
improves the moisture as well as nutrient status in valley areas. Once established,