DIVERSITY OF TREES AND BUTTERFLIES IN FOREST FRAGMENTS AROUND PUNE CITY 

Vaijayanti Alkutkar, Prajakta Athalye, Shweta Adhikari, Anagha Ranade, Mandar Patwardhan, Krushnamegh Kunte and Ankur Patwardhan*

* Research And Action in Natural Wealth Administration (RANWA), C - 26/1, Ketan Heights, Kothrud, Pune - 411029, Maharashtra, India.
 e-Mail : ranwa@pn3.vsnl.net.in
Corresponding author - ankurpatwardhan@hotmail.com

Key words - Tree Diversity, Butterfly Diversity, Defence Area, Conservation. 

Drastic changes in land use pattern associated with urbanization have resulted in an immense impact on those fringe areas of human habitations where forests are situated. The present paper discusses variation in diversity of trees and butterflies in different impact zones across natural and semi-natural vegetation types close to Pune city. We also argue for the important role played by the Defence Services in protecting the forests that may act as sources of plant and animal populations, and may also serve as forest islands and as migratory corridors. 

Pune city, close to which all study sites were located, is situated at 180 31' N lat. & 730 51' E long., at the junction of the Deccan Plateau and the Western Ghats. For evaluating the role of human influences, the present study, conducted during 1999-2000, compared the diversity of trees and butterflies in the forest patches at Katraj, Parvati-Pachgaon, Vetal Hills, Sinhgarh and National Defence Academy or NDA (abbreviated as K, P, V, S and N, respectively). Currently, we have not corrected for the differences in sizes of these fragments but efforts are on to compare those fragments on the basis of similar sized transects. Katraj hills harbour a mosaic of dry deciduous forests with 5-10m tall trees, and grasslands. NDA campus is moister, and houses taller (10-15m) forest and scrub, prone to fire (Patwardhan and Gandhe, 2000-2001). Sinhgarh hosts the most moist forests in the area, with tallest trees (15-20m) in the valley (Santapau, 1951). The scrub at Parvati-Pachgaon and forest at Vetal Hills have dwarf (3-6m), scattered wild trees as well as exotic ones planted.

To facilitate comparison, the habitats were arranged in their increasing order of relative human impact as forest, scrub, plantation and habitation. The former two categories host mostly indigenous flora constituting the wilderness zone, i.e. low impact zone. The latter two represent species that are cultivated, mostly exotics, constituting the influenced zone. The species are classified on the basis of habitat preferred as forest species, scrub species, plantation species or species that are cultivated in house gardens as habitation species. A qualitative abundance scale was used to classify the species encountered as very common (VC), common (C), occasional (O) and rare (R). Species confined to just one habitat was termed exclusive to it. 

Results : 

Total 131 tree species, of which one was an addition to the flora of Pune, were recorded from the study areas. Maximum number (81%) and density of tree species were recorded from NDA, which is a low impact area. Minimum number of species were recorded from Parvati-Pachgaon (58%), a high impact area. Tree species richness (number of species), and number and percentage of species found exclusively at each locality are given in table 1. Number of species in wilderness and influenced zones are also given. Figure 1 reveals that percentage wilderness of trees increased as the distance between the city and the forest/scrub increased.

A total of 103 butterfly species were recorded from the study sites. Their habitat preferences as well as seasonal species richness at various sites may be found elsewhere (Kunte 2000-2001). The number of species in late monsoon and winter were far higher at Parvati-Pachgaon, the high impact area, than at any other site, including the low impact areas. However, during other seasons, the low impact areas had greater species richness. In any case, the low impact forested areas of Sinhagad and NDA supported more number of habitat specialist butterfly species than any other site.

Discussion :

Though populations of certain forest butterflies may possibly have declined in past few decades due to reduction in forest cover (Kunte 2000-2001), no species have reportedly gone extinct in the neighborhood of Pune city. However, Joshi et al. (1992) reported loss of four tree species due of impact of biotic factors from Vetal Hills. It is important to note that these species are still common at the sites in the low impact zone (Sinhagad and NDA). At this backdrop, the importance of those forests that are protected by Defence Services needs to be carefully assessed. This study reveals that species richness as well as percentage wilderness of trees at NDA is comparable with Sinhagad that supports a good forest patch. Though butterfly species richness was higher at the high impact site of Parvati-Pachgaon, there were more exclusive species at Sinhagad and NDA. This highlights the point that Defence Services-protected forests enjoy a high degree of protection that assist in conservation of various floral and faunal components, and possibly the overall biodiversity. In the light of recent observations that the practice of maintaining sacred groves is degenerating at the face of urbanization, we may be correct in suggesting that Defence Services-protected forests may emerge as modern sacred groves. Such forests are distributed throughout the country in various ecological zones, including the extremely biodiverse areas such as the Himalayas and the NE India. Studying further these forests vis-à-vis other protected and unprotected forests may elucidate the presently neglected potential of the Defence Services-protected forests as floral and faunal conservation areas.

Acknowledgments : 

We are grateful to the-then Commandant, National Defence Academy, Pune, for permitting us to conduct surveys at Peacock Bay. We acknowledge the cooperation of the following individuals; R. Khunyakari, S. Kavade, S. Punekar, R. Mungikar, S. Bhagwat and M. Pendse. Our sincere thanks are also due to Four Eyes Foundation, Pune , for their infrastructure support. 

REFERENCES :-

JOSHI, V. N., KUMBHOJKAR, M. S. AND KULKARNI, D. K. 1992. Changing floristic pattern of Chatushringi-Vetal plateau near Pune- A comparative study. J. Econ. Tax. Bot. 16:133-139.

KUNTE K., 2000-2001. Butterfly diversity of Pune city along the human impact gradient. J. Ecol. Soc., 13/14:40-45.

SANTAPAU H., 1951. A contribution to the flora Sinhgad hill, Poona district. Poona Agri. Coll. Mag. 41(4): 270-284.

PATWARDHAN, A.A AND GANDHE, R.V., 2000-2001. Tree diversity of Pune urban area : Cosmetic increase? J. Ecol. Soc., 13/14:21-33.