OCCASIONAL PAPER NO. 152 Records of the Zoological urvey of India Consumer & Deeornposer Arthropods In Pine Plantations of Meghalaya, N. E. India - A Biodivenity and Ecological Analysis M. V. Reddy Department of Zoology. Nonh of Hill University, Shillong Wld J.R.B. Alfred Eastern Regional Slation, Zoological Survey of Jndi:!, ShjJlong Zoological Survey of India RECORDS OF THE ZOOLOGICAL SURVEY OF INDIA Occasional Paper No. 152 Consumer & Decomposer Arthropods in Pine Plantations of Meghalaya, N. E. India - A Biodiversity and Ecological Analysis By M. V. REDDY Department of Zoology, Nortll of Hill University, Shillong and J.R.B. ALFRED Eastern Regional Station, Zoological Survey of India, Shillong Edited by the Director, Zoological Survey of India ZOOLOGICAL SURVEY OF INDIA 1992 © Copyright, 1992 Government of India Published: December, 1992 Price Indian Rs. 140.00 Foreign : $ 10.00 £ 7.00 Published by The Director, Zoological Survey of India, Calcutta Laser set by Neatpoinl Photocomposers, 6A Sudder Street, Calcutta 700 016 and printed by Independent Printers, Cnlculla 700 026 RECORDS OF THE ZOOLOGICAL SURVEY OF INDIA OCCASIONAL PAPER No. 152 1992 Pages 1-129 INTRODUCTION 1 STUDY AREA 2 REVIEW OF LITERA TURE 5 MATERIALS AND METHODS 14 RESULTS 16 DISCUSSION 89 REFERENCES 105 SUMMARY The present work was confined to a very restricted range of trees dominated primarily by pine' (Pinus kesiya Royle). Investigations on the biodiversity of invertebrate fauna, particularly arthropods, which were associated within a range of ecological conditions were studied in detail. The forest sites undertaken were ncar-to-natural ecosystelns since they were an outcolne of plantations managed over several years. At the outset this forest was divided into two major divisions for easier analysis of the consumer populations. The young plantations were analysed for sap-sucking consumers and the older ones for chewing and mining insect consumers, the latter by the light trap method. For decomposer studies both soil and 1i1Ler fauna were analysed in the oldest plantations 10 help in elucidating the return of nutrients to the soil. An attempt has been made to interrelate these different components to get a total understanding of the ecosystem considered. Both the aspects dealing with fauna at the consulner level had many attributes of similar nature probably proving that the effect of environillental factors on the species of populations considered was in a regular systelnatic manner. The prediction of populations for succeeding years stood as one very important feature enabling control of species if and when they would reach pest status. Most populations had distinctive biomodal patterns of fluctuation over an annual cycle. Temperature and rainfall were two factors which seer:ned to playa major role in regulation of both sap-sucking, and chewing and mining conSUlners, proving either one of these factors as operationally significant. In those cases where statistical significance of anyone factor on a population failed to express itself it was seen that a highly significant relationship existed when a multiple correlation was computed for all factors with the groups of populations considered. There was a decrease in the population abundance of the species considered during the second year of investigation proving thereby that rates of increase never reached beyond the net biotic potential known to be effected by factors like emigration, predators and parasites. The next aspect dealt with the role of microarthropods in plant litter decomposition and their importance in soil. In both cases Collembola and Acarina formed the dominant groups. One common factor effecting their population levels was water content as rainfall for soil and moisture for liller. pH was another factor which positively influenced the soil organisms and understandibly much Inore in the pine lillcr. There was a clear indication of an interplay between Collembola and Acarina with the season, for sUlnmcr had a dominance of Collembola, while the winter months revealed a greater activity of Acarina. One of the effects of faunal population on detrital processing was cOlnminution which exposed greater surface area for microbial action. The average turnover rates for the trophic levels studied, changed during the season as temperature and moisture changed and populations underwent shifts in abundance. The results of this study had an unique advantage of these elnerging general concepts of ccosystcln, in that unlneasured ecosystem parameters could be predicted. On thc one hand community dynamics were interpreted whenever possible as population phenomena, and on the other hund population biology was studied only within the cOlnlnunily concept. What had caneegcd reoan this study of comnllinity analysis was to identify the kinds of research for the next phase and that greater opportunities existed for building models and to solve the underlying machanisnls of integration between the cOlnnlunity and the population. CONSUMER & DECOMPOSER ARTHROPODS IN PINE PLANTATIONS OF MEGHALAYA, N. E. INDIA- A BIODIVERSITY AND ECOLOGICAL ANALYSIS M. V. REDDY· Department o/Zoology, North 0/ Hill University, Shillong and J.R.B. ALFRED·· Eastern Regional Station, Zoological Survey 0/India, Shillong INTRODUCTION Forests vary greatly in structure, their productivity and turnover rates in general, though offering a stable microhabitat. The physical conditions of the microclimate and consequently the microhabitats are generally important in determining the composition of fauna (Stout, 1974). Trees and forests have always been subjected to dual attitude, on the one hand a feeling of beauty, awe, reverence or mystery and on the other a sense of utility, a desire to cut them down, make houses and bridges and clear the land for farming, as seen throughout mans history (Botkin and Miller, 1974). The need to study forest systems, stems from the need to understand, not only as a value for mans soul - his recreation and aesthetic appreciation, but to understand those organisms that exist in communities involving many biological interactions. It is in this context, that the forest ecosystem is relevant not only to professional ecologists but also in view of mans present day environmental problems that it has been studied in greater detail than ever before. This led Odum (1971) to define ecosystem from both anthropocentric and professional angles. Either definition involves the structure and function of a system under consideration. The word Ecosystem coined by Tansley (1935) had passed through a phase of related terminologies like Biocenosis (Mobius, 1877), Microcosm (Forbes, 1887) and Biogeocenosis (Sukacheva, 1944). However, no one has expressed the ecosystem concept to man better than Leopold (1933) who wrote, that christianity tries to integrate the individual to society, democracy to social organisation in the individual, with no ethic of man's relation to his environment. It is for these reasons that ecological processes have been traditionally studied from convenient vantage points. Three of these could be identified, (1) the geographical distribution of species and their relationships between species diversity and area, (2) species interactions in terms of population dynamics and (3) energy flow in ecological communities from primary producers to consumers through higher trophic levels (Rapport and Turner, 1975). With these in mind the present investigation was undertaken from a merological point of view where parts of the system could be studied and finally to build up a whole. The ambition was soon realised to be far fetched when, as the work progressed, it dawned, that we had to start from scratch. Though ideal to study all the three components defined above, a total understanding of all aspects Present Address • Department of Environmental Science, Kakatiya University, West Bengal •• Zoological Survey of India, 234/4, AJ.C. Bose Road, Calcutta 2 Rec. zool. Surv. India Occ. Paper No. 152 and from all points of view was virtually unattainable. The present study was therefore, confined to the understanding which was required to use it for some specific purpose and the nature of this purpose was the outcome of the present work. As mentioned earlier, about the diversity in forest ecosystems, the present work was confined to a very restricted range of trees dominated primarily by pine (Pinus kesiya Royle). Investigations on the kinds of invertebrate fauna, particularly arthropods, which were associated within a range of ecological conditions were studied in detail. The forest sites undertaken were near-to- natural ecosystems, since they were an outcome of plantations managed over several years. Two major factors affecting this system were the consumers and decomposers. The questions we asked ourselves, to enable the realisation of the objectives of the present study were, (1) What were the dominant arthropod groups?, (2) What were their population dynamic relationships?, (3) What were the detrimental and beneficial effects of these, on the forest stands, and (4) How much was their functional interplay? At the outset we divided the forest into two major divisions for easier analyses of the consumer populationS. The young plantations were analysed for sap-sucking consumers and the older ones for chewing and mining insect consumers, the latter by the light-trap method. For the decomposer studies both soil and litter fauna were analysed to help in elucidating the return of nutrients to the soil. An attempt has been made