Abstract:
In general, different characteristics of soil ecology lead to the differences in
soil fauna, especially soil arthropods. The density of soil arthropod families in
disturbed and undisturbed forests near Mo Sing To Reservoir, Khao Yai National
Park, Thailand, were compared during the period of September 2002 to August
2003. The disturbed forests are grassland, a Crassna plantation and a secondary
forest whereas the undisturbed is a natural forest. Soil samples from the four areas
and litter from three areas (grassland excluded) were collected and extracted for
mesofauna by Berlese-Tullgren funnel (mesh 2x2 mm2.). Soil properties (pH,
organic matter, P, K, and moisture content) in four areas were recorded and found
to have no significant differences, whereas litter mass and litter moisture were
significantly higher in the natural forest (p<0.05).
It was found that 99.45 % of total fauna in soil and litter were phylum
Arthropoda and 0.55 % were Nematoda and Annelida. Among arthropods, The
density of mites in families Macronysidae and Cunaxidae were significantly higher
in September 2002 and February 2003 (when the soil moisture was low) than in
other months (p<0.05). There were no significant differences of densities between
months in all other animals. The dominant arthropods in grassland were springtails
(Order Collembola: Class Hexapoda) but those in Crassna plantation, secondary
forest, and natural forest from both soil and litter collections were mites (Order
Acarina: Class Arachnida). The highest density of springtails (except family
Isotomidae) in soil was in the grassland (166.387 m-2), followed by those in Crassna
plantation (103.883 m-2) and secondary forest (41.521 m-2), and the lowest was in
natural forest (36.529 m-2). In the contrary, springtails in litter was highest in
natural forest (135.688 m-2) and lowest in Crassna plantation (20.142 m-2). The
densities of mites in the family Haplozetidae, pseudoscorpions (Order
Pseudoscorpiones: Class Arachnida) and rove beetles in the family Pselaphidae
(Order Coleoptera: Class Hexapoda) from both soil and litter were significantly
higher in natural forest than in the three disturbed areas (p<0.05). These four
arthropod groups, therefore, could probably serve as primary indicators
distinguishing between undisturbed and disturbed forests at Khao Yai. When the
correlation between the litter properties and the arthropod density was considered, it
was found that the densities of mites and rove beetles were high in litter with high
mass and moisture content. The density of pseudoscorpions was positively
correlated only with the moisture content while in springtails, the density was high
when the litter mass was high. This is in accordance to the high densities of both
groups found in the natural forest. Thus, these two groups could be primarily
accounted as indicators in litter in different forest types at Khao Yai.