Tree Diversity of Pune Urban Area: Cosmetic Increase?

Ankur. A. Patwardhan

Abhayankur, 14 Nityanand Society, Dhankawadi, Pune - 411043
Email: ankurpatwardhan@hotmail.com

Introduction

Trees are amongst most significant elements of landscape, both due to biomass and diversity. Tree diversity of Pune Corporation Campus (PCC) was first comprehensively recorded by Vartak (1964) who had earlier (1960) recorded the floristic composition of Katraj hill forests. This area was resurveyed partially by Varadpande (1973) while fully by Ghate (1989). Amongst hill forests, Kulkarni et al (1989) studied the vegetation composition of Parvati-Pachgaon. recorded the diversity in Ganeshkhind area. In 1990 The first attempt to detect floristic changes was by Joshi et al (1992) who later (1997) also recorded plants from Vetal hills. Besides attempting another re-survey for change detection, the present study also evaluates role of human influences at a broad level, in and around Pune city.

Methodology

The present paper is based on survey during 1999 and 2000, of the PCC and neighbouring hills viz. Katraj, National Defense Academy (NDA) campus and Sinhgarh. Various localities within this area were visited for species enumeration during different seasons, with focus on localities indicated in the literature as hosting rare species. Katraj hills harbour dry deciduous forests, with 5-10 m tall trees, often interspersed amidst grasses. NDA campus is moister, and houses taller (10-15 m) forests and scrub, prone to fire. Sinhgarh houses most moist forests in the area, with tallest trees (15-20 m) in the valley. The forests within the PCC are located at Parvati Pachgaon, Law College (Vetal, Bhamburda) hills and are comprised dwarf, scattered natural trees (3-6 m tall) amidst planted exotic trees. At each of these localities, ecological preferences of each species, influencing factors etc. were also noted and discussed with local people.

Results And Discussion

A total of 380 tree species have till date been recorded from the study area, two third of them being cultivated, mostly exotics and one third wild, native. To begin with, Vartak (1964) recorded 293 tree species from PCC that forms much of the present study area. Three fourth of the trees were recorded at present within PCC. Ghate (1990) and present survey added 33 species to list but could not record 57 species recorded by Vartak (1964), majority of them being exotic species of Eucalyptus or palms. Some of these may not be actual losses but surprising misidentifications by Vartak (1960) such as Bocagea dalzelli, known since long to inhabit evergreen-semievergreen forests much moister areas, nearest locality from Pune city being 70 km away (Santapau, 1958). Some glaring omissions by Vartak (1960) include commonest species such as Sterculia urens, Semecarpus anacardium, Miliusa tomentosa,, Madhuca indica, Parkinsonia aculeata, Diospyros montana and Randia dumetorum. Thus on the whole, the floritic richness of the study area remains much the same notwithstanding the striking differences as per the records. However, Joshi et al (1992) have reported loss of 30 flowering plants including 4 tree species viz. Grewia laevigata, Morinda citrifolia,, Randia dumetorum and Schrebera swietenoides over the last 7 decades from Vetal Hill due to human pressures like cutting and fires. However, these species do exist elsewhere such as Katraj at present.

Wide niched species include Mangifera indica, Syzygium cumini, Ficus benghalensis, F. glomerata, Pongamia pinnata and Cassia fistula that inhabit most habitat types and localities. Dominant forest species include Tectona grandis, Odina wodier, Terminalia bellerica, Buchanania lanzan, Gmelina arborea, Cochlospermum gossypium etc. C. gossypium and Diospyros melanoxylon show clumped distribution. Holarrhena antidysenterica and Helicteris isora form the forest undergrowth. Scrub is dominated by thorny species such as Acacia leucophloea, A. chundra, Zizyphua xylopyra, Meytenus rothiana etc. while F. arnottiana inhabits rocky outcrops. Pongamia pinnata and Syzygium cumini are predominantly seen near ravines, especially streambanks.

Most poular plantation and habitation dwelling trees are exotic and include Rain tree (Samnea saman ), Copper pod ( Peltophorum ferruginum), Gulmohar (Delonix regia), Silver Oak (Grevillea robusta ), Bottle palm (Roystonea regia), Asoka (Polyalthia longifolia var. pendula) Fountain tulip (Spathodea companulata) Sayami Cassia (Cassia siamea) Neelmohor (Jacaranda mimisaefolia) and Cork (Millingtonia hortensis). Trees dominating plantations particularly on forest department lands include Eucalyptus, Gliricidia, Leucaena and Dalbergia sissoo. Unfortunately, the increase in populations of most of these exotic, ornamental trees has been at the cost of local, fruit tree species with decreasing populations over the last few decade. These include Neem (Azadiracha indica), Mango (Mangifera indica), Jackfruit (Artocarpus integra) Tamarind (Tamarindus indica), Jamun (Syzygium cumini), Guava (Psidium guajava), Banyan (Ficus bengalensis), Peepal (F. religiosa) and Wild fig (F. glomerata). Some of them like the figs (Ficus spp.) were common as avenue and habitation trees earlier, but no more planted and in fact chopped down due to increasing congestion. Mango, Guava etc. were common in orchards along city fringes but now encroached by housing colonies. The famous Babul-van i.e. gallery thorn forest along river banks dominated by Acacia nilotica trees are all cut and encroached, which has also erased stretches of Wild date palm (Phoenix sylvestris).

Our patterns of species distributions and changes parallel those reported by Gadgil and Parthsarathy (1977) for Bangalore city, though we have no census unlike them. Such dynamics could be quantified for making feasible, informed recommendations by accessing and analysing the enormous tree census data available with the Municipal Corporation (Khaire Y., pers. comm.)

Acknowledgements

RANWA sponsored this study. Utkarsh Ghate and Mandar Datar shared their data and ideas. These studies have been greatly encouraged by Mr. Y.S.Khaire, Garden Superintendent, PCC, besides my liberal guide Dr. Gandhe. I am obliged to them all.

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Table 1 Species richness recorded by successive surveys

The surveys compared include Vartak (1964), Ghate (1990) and Patwardhan (present)

Table 2 Tree species richness and exclusiveness across habitat types

ANNEXURE : Tree species distribution in Pune urban area

HB (Habitat Preference): F - Forest, S - Scrub, P - Plantations, H - Habitations

AB (Abundance): A- abundant, C- common, O- occassional, R- rare

AU (Authors): G- Ghate (1990), P- Patwardhan (present), V- Vartak (1964)

Localities: AGC- Abasaheb Garware College, BG- Bund Garden, BMCC- Brihan Mharashtra College of Commerce, BSI- Botanical Survey Of India, DG- Deccan Gymkhana, EG- Empress Garden, FCBG -Fergusson College Botanical Garden, FN- Forest Nursery, JNH - Jawaharlal Nehru Herbarium, K - Katraj, KG - Kirkee Garden, KNP - Kamla Nehru Park, MACS - Maharashtra Association For Cultivation Of Sciences, N-National Defense Academy, NIBM - National Institute Of Business Management, P - Parvati-Pachgaon, PUC - Pune University Campus, PUC-BG - PUC Botanical Garden PUC-MB- PUC Main Building, S-Sinhgarh, SN- SN, SPC - S. P. College.