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Academic Journal of Entomology 7 (1): 32-37, 2014 ISSN 1995-8994 © IDOSI Publications, 2014 DOI: 10.5829/idosi.aje.2014.7.1.81253 Invertebrates in Canopy and Ground Organic Matter in a Tropical Wet Evergreen Forest of Southern Western Ghats, India 1 T. Mohanraj, 1Albert Rajendran, 2M. Soubadra Devy and 2R. Ganesan Department of Zoology, St. John’s College, Palayamkottai, Tamil Nadu, India Ashoka Trust for Research in Ecology and the Environment (ATREE), Bangaluru, India 1 2 Abstract: In a tropical wet evergreen forest of India, in Kalakad Mundanthurai Tiger Reserve of southern Western Ghats. The density and composition of invertebrates in organic matter found within the various area of canopy and litter of the forest floor were compared. Berlese funnel trap was used to extract invertebrates from accumulated epiphytes and litter. The numerically dominant invertebrate groups among epiphytes of the canopy were ants, beetles, cockroaches, spiders and in the forest floor leaf litter were amphipods and isopods. Relative abundances of these major taxa were not the same in the canopy and on the forest floor, indicating that canopy organic matter shares a less dissimilar invertebrate community with that of the forest floor. Key words: Formicidae Amphipoda Ground Litter INTRODUCTION Tiger Reserve energy source for hetetotrophs and as a reservoir for plant mineral nutrients [7-9]. Because litter fall is a major pathway of nutrient and energy flux in most forests, almost all of this research has focused on the abscised plant material located on the forest floor [10-12]. Epiphytes interact with animals in all of the ways that promote reproductive success among seed plants generally. Insects are the most successful rainforest animals as demonstrated by their tremendous diversity. Primary tropical rainforest is vertically divided into at least five layers: the overstory, the canopy, the understory, the shrub layer and the forest floor. Each layer has its own unique plant and animal species interacting with the ecosystem around them. The overstory refers to the crowns of emergent trees which soar 20-100 feet above the rest of the canopy. The canopy is the dense ceiling of closely spaced trees and their branches, while the understory is the term for more widely spaced, smaller tree species and juvenile individuals that form a broken layer below the canopy. The shrub layer is characterized by shrubby species and juvenile trees that grow only 5-20 feet off the forest floor. The forest floor is the ground layer of the forest made up of the trunks of trees, fungus and low-growing vegetation. These layers are not always distinct and can vary from forest to forest, Forest canopies contain a major portion of the diversity of organisms on Earth and constitute the bulk of photo synthetically active foliage and biomass in forest ecosystems. Historically, forest canopies have been among the most poorly understood regions of our planet. Initially, people who sought the thrill of climbing and followed the lure of discovering new species dominated canopy studies. Many forest canopy ecosystems promote intensely diverse plant communities such as vascular and non-vascular epiphytes, hemi-epiphytes and parasites [1-3]. Canopy-dwelling plants provide largely to overall forest biodiversity by contributing resources for a diverse aggregation of arboreal vertebrates, invertebrates and microbes [4, 5]. Global estimates of 30 million invertebrate species by Erwin [6] were principally based on early canopy fogging studies in lowland tropical forests. These estimates were a key driver in the formulation of species coexistence and habitat specialization models. Invertebrates appear to layer vertically at the species level, though there may be imbricate between forest floor and canopy at the genus and family level [7] A major portion of forest nutrient cycling research has focused on the storage and circulation of dead and decomposing organic matter, because it is important as an Corresponding Author: T. Mohanraj, Department of Zoology, St. John's College, Palayamkottai, Tamil Nadu, India. 32 Acad. J. Entomol., 7 (1): 32-37, 2014 but serve as a good model of the vegetative and mechanical structures of the forest [13]. One important functional aspect of dead organic matter is the composition and abundance of the detritivore fauna it supports. In addition to the pools of nutrients and energy in their own biomass, detritivores participate in the regulation of nutrient transfer. Invertebrates are the main agents of litter fragmentation and mixing of leaf litter with mineral soil, exposing a greater surface area for microbial colonization [14-17]. In this study, we quantitatively compared the composition and abundance of invertebrates that inhabit canopy and ground litter in a tropical wet evergreen forest. within 15cm2 was removed from the substratum carefully and put in the poly bag. Two such samples were collected, one closer to main trunk and other at outer limb (peripheral region). Totally sixty epiphytic load sampling (from thirty trees) was done in the canopy alone. Polybags were labeled and tied to assure that insects did not escape. Litter sampling from the forest floor were collected under the same tree. Quadrate of 15x15cm was placed in the forest floor and macro litter with mixture of soil and fragmented litter were collected in a poly bag. Litter collection was carried out fewer than thirty tree sites in the forest floor. Invertebrates from the canopy and forest floor litter were extracted using Berlese funnel trap, an extraction technique in which the collected litter was kept over a funnel with different mesh size of sieves. The tip of the funnel was inserted inside a sample bottle with 70% alcohol. The funnel was covered with a 100w incandescent bulb. Invertebrates slowly leave the drying litter and fall into the alcohol due to the heat emitted from the bulb. After extracting the invertebrates the litters were allowed to dry. Invertebrates were sorted with a dissecting microscope and counted. Invertebrates were separated into three categories: insects, non arthropod insects and others. Data were tabulated and, species richness and similarity indices calculated. MATERIALS AND METHODS Study Area: Field research was conducted in the Kalakad Mundanthurai Tiger Reserve (KMTR), in Western Ghats (8°33’35”N; 77°22’93”E), from February to May 2008. These ranges constitute 5% of the total land area of India but harbour 30% of India’s biological species [18]. KMTR is known for its rich biological diversity lying in the southernmost part of the ‘Hotspot 25’ [19]. Well-developed root systems occupy the upper 0-15 cm of soil and substantial amounts of organic matter ate incorporated into the upper horizons. Relative to the forest floor, the upper tree canopy experiences more wind [20], more frequent mist, higher air temperature maxima and more frequent wetting/drying cycles. Nearly all of the branch interiors, crotches and trunks of mature trees are covered with thick epiphyte mats [21]. RESULTS AND DISCUSSION The numerically dominant family in both canopy and ground litter were Formicidae, Tenebrionidae, Staphylinidae, Carabidae, Archinids and Isopods. Members of these families are no doubt the major agents of fragmentation of organic matter at the study site. Formicidae (Fig 2a) is the richest insect family in the samples. The similarity index value for the invertebrates both in canopy and forest floor was 42.3 %. Total invertebrate abundance was higher on the canopy than in the ground for all sample pairs, with a mean density 1.7 times greater on the canopy than in the forest floor. Terrestrial crustaceans (amphipods), the largest invertebrates in the samples, were readily visible on the ground, but not seen in the canopy samples. Arthropod diversity in tropical forests represents a concentration of biodiversity locally, regionally and globally. Arthropods carry out many significant ecosystem processes, notably decomposition, herbivory and pollination and they also represent a food source for many vertebrate species. In panama, light traps caught as many more insects at 20 or 26 meters than at ground level. This difference held for Coleoptera, Ephemeroptera, Field Methods: Trees from which samples taken were chosen to include the largest size class of the most common tree species in the forest [21]. The thirty samples were collected from Cullenia exarillata. This tree species support large accumulations of live epiphytes and contiguous mats of crown humus on trunks and interior branches [22]. Climbing of tree was done by Single Rope Technique (SRT). This single rope technique allowed us to explore even the restricted areas from which we collected material to the interior branch regions of the mid and lower crown (10 to 18 m above ground, to 4 m from central trunk); the area where epiphyte mats within tree crowns is located. A quadrate of 15 x 15cm made with flexi wire was placed over the epiphytic mat. Then a poly bag was placed downward to the bark and the litters carefully collected using scrapers and brushes. The epiphytic mat 33 Acad. J. Entomol., 7 (1): 32-37, 2014 Fig. 1: Map showing the study area Kalakad Mundanthurai Tiger Reserve Fig. 2 a: Abundance and diversity of insect families found in canopy and ground litter > 3 in numbers Fig. 2 b: Abundance and diversity of insect families found in canopy and ground litter <3 in numbers than in the tropics [30]. Studies with emergence traps reveal that these insects originate in the forest floor or streams, where they feed as larvae. This input of adult insects from the forest floor may provide a food source for spiders and other canopy predators during the winter and early spring and serve to maintain their populations at high levels throughout the year [31]. However, the height distributions of insect abundance, comparable to those reported in tropical forests [23,24,28,29] have not been measured in temperate forests. Probably, tree crowns are accountable to greater amounts of isolation, wind and more persistent to wetting and drying cycles than the forest floor [32-35]. Hemiptera, Hymenoptera and Lepidoptera [23]. In lowland rain forest sites in Brunei, Panama and Papua New Guinea, Canopy light traps caught more insects of most groups, including Coleptera, Diptera, Hemiptera, Homoptera and Hymenoptera, at 30 and 20 m than at ground level [24]. Many abundant tropical insect species appear to be tied throughout their life cycle to the canopy [25].The high species diversity of tropical forest arthropods is sustained in part by the large number of insects in the canopy [26,27]. The tropical rainforest insects are more abundant in the canopy than near the forest floor [22, 23, 25, 27-29]. Recent studies suggest that the diversity of arthropods in the canopies of temperate forests is substantially less 34 Acad. J. Entomol., 7 (1): 32-37, 2014 they have not overwhelmingly radiated into or made use of the canopy, as have the invertebrates. Elucidation of which factors depress invertebrate density in the canopy and conversely, which canopy organic matter characteristics may be caused by depressed invertebrate density, awit further investigation. We have shown that canopy-held organic matter, an ecosystem component of tropical wet evergreen forests, differs from forest floor organic matter in an important biotic characteristic. This implies that organic matter in the canopy should be treated as a separate compartment in ecosystem studies and cannot be subsumed under studies of organic matter on the forest floor. ACKNOWLEDGEMENT Fig. 3: Abundance and diversity of non insect arthropods found in canopy and ground litter *NMT-Near to Main Trunk; FPR-From Peripheral region; GL-Ground Litter We thank the Ashoka Trust for Research in Ecology and the Environment (ATREE), Bangaluru for funding and logistical support. Numerous studies have detailed sensitivity of invertebrates to microclimatic regimes, particularly moisture, temperature and isolation; many important detritivore groups tend to drop out with increasing desiccation. Insects particularly and some of their allies, have adapted to nearly every physical feature of the planet and the canopy is no exception. Many beetles have special feet for walking on leaves; some even have modified setae on their feet to slow them down upon landing from rapid flight. Because they are in an environment with raptorious birds, lizards and frogs, many insect species have evolved camouflage coloration. Climate is the main constraint on terrestrial invertebrates. In the temperate zones, it is the winter cold and dryness; in the equatorial tropics, it is the dry season for some and the rainy season for others, with the temperature far less of an influence than it is in the far north or south. Many herbivores must contend with plants that produce toxic chemicals or other defensive systems. All insects must also deal with other insects that predate, parasitize, or carry bacteria, fungi, or other insect diseases. Hammond, Stork and others, in their studies of insects in the Sulawesi dipterocarp forests and Miller, Basset and others in New Guinea found much less insect diversity and richness than Erwin and his teams in the Neotropical forests. Hammond also found in southwest Asia that the canopy fauna was not as delimited from the understory fauna as it is in the Amazon Basin. Terrestrial crustaceans are very sensitive to moisture conditions [36] and were abundant in the ground litter samples (Fig 3). 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