Departmant of Agric. Biology  
2006

Comparison of the Soil – Litter Invertebrates in Natural and Agro Ecosystems At Tissamaharama Area

Tharanga D.G.N., Punchihewa R.W.K.1

Faculty of Agriculture, University of Ruhuna

ABSTRACT

Features of a soil are determined by the type of ecological system and its interactions in which soil inhabiting invertebrates play a dominant role to sustain the soil conditions in the system. They keep soil healthy and sustainable forever if their functions are not disturbed by any factor like man. Therefore, diversity and abundance of soil and litter inhibiting invertebrates in any ecosystem are of great importance for whole system as they determine the existence of the system through recycling litter on the ground cover inhibitors and surrounding environmental and other soil factors are interdependent for their smooth functioning.

The objectives of the study were to identify meso and macro invertebrates in dry zone natural forest and comparable agro – ecosystem, and to compare abundance and distribution of meso – and macro – soil fauna in each eco system. The study was conducted in ecosystems of tropical dry mixed evergreen forest, a vegetable cultivated land and a Jatropha cultivated land.

The study, 10*10 m area was selected in each of the ecosystem and four sampling techniques, namely habitat sampling, pitfall method, litter technique, sieving and hand sorting method were employed to extract soil and litter inhabiting invertebrates. Then extracted fauna were identified through visual observation by naked eye, stereo microscope and by comparing them with available reference voucher specimen. The diversity and abundance of Collembola, Mites and other invertebrates of each ecosystem were recorded and analyzed using Shannon index. Finally the data of each ecosystem was compared with other two systems.

The results revealed that density of Collembola and Mites are most abundant invertebrates in each of the ecosystem.

Highest category diversity was recorded in forest land, while lowest diversity was in Jatropha cultivated land. Vegetable land fell in between the above two with intermediate categories of diversity

Although abundance distribution of soil and litter inhibitors in forest and vegetable land showed significant variation, the abundance of different inhibitors in Jatropha land was equally same.

The study clearly showed that man made disturbs directly affect all the conditions of soil litter inhibitors since they indicated their abundance and diversity lowest in Jatropha cultivated land and highest in natural forest.