Population dynamics of earthworms and their activity in forest ecosystems of North-east India

Abstract

ABSTRACTA comparative analysis of earthworm populations in seral Khasi pine forest represented byPinus kesiya5- and 35-year old stands, and a climax broad-leaved mixed forest represented by a sacred grove was done at altitudes of 1500 m in Meghalaya in north-east India.Tonoscolax horaiioccurred under all forest types whereasAmynthas diffringensandEulyphoeus feslivuswere confined to pine forest stands only.Perionyxsp. andDrawida assamensiswere restricted to the sacred grove.T. horaiihad larger numbers in all three different forest types. This species offers possibilities of vermicullurc for biologically improving soil fertility in manmade ecosystems because of its wide range of tolerance.Generally earthworm populations were more active during the monsoon season;A. diffringenswas however, more active during the winter, thereby conferring an advantage on this species as it was enabled to avoid competition during the monsoon season when other species dominate. Earthworm activity was generally higher in the sacred grove than in the pine forest stands. Population size was significantly correlated with soil moisture, temperature and pH. Wormcasts had a higher pH and nutrient status than the soil.In the highly leached soils of the humid tropics where there is a large concentration of fine root biomass in the surface soil layers, earthworm activity is beneficial because it helps incorporate detritus into the mineral soil rapidly and locally concentrates nutrients in the surface layers.