0756-B2

Plant Biodiversity of Uttaranchal, Central Himalayan Forests, India

Jeet Ram*, A. Kumar and J. Bhatt ¹

Abstract

Forest diversity is the main source of livelihood of the people living in the Uttaranchal Central Himalaya. Agriculture is the nucleus around which all the human activities are centered. Forest biodiversity is used for fodder, fuel wood, timber, leaf litter for manuring crop fields, construction, industrial raw materials and several non-timber forest products. Non-timber forest products include gums, resins, dyes, fibers, medicin, oil, honey, spices and several other produces. Quercus (oaks) and Pinus roxburghii Sarg. (chirpine) are the major forest forming tree species in this region. These forest species are mixed with other broad leaved and coniferous trees. P. roxburghii forest, generally, grow pure with low total species richness of shrubs and herbs while mixed broad leaved forest has high total species richness. Shrubs and herbs showed higher species richness in P. roxburghii -mixed broad-leaved forest and low richness in Quercus semecarpifolia Sm. forest. Q. leucotrichophora A. Camus, forest has high tree diversity while shrubs and herb diversity is highest in Cupressus -Quercus mixed forest. These forests are exploited variously for different resources and consequently the vegetation cover is decreasing. These disturbances are changing the species richness and diversity, which influences the soil and environmental conditions. Thus, the conservation and management of these forests will be important for the sustainability of human and land. Disturbances and climatic change will alter the species composition of these forests, which may shift socio-economic and ecological condition of the region.

Introduction

The most striking features of the earth is the existence of life and most striking features of life is the diversity. Topography, soil, climate and geographical location of the region influence the vegetation diversity of the forest ecosystem of Himalaya. The Himalayan forest vegetation ranges from tropical dry deciduous forests in the foothills to alpine meadows above timberline (Singh and Singh 1992). Forest diversity is the main source of livelihood of the people living in Uttaranchal, Central Himalaya. India is among the important mega-biodiversity centers of the world and the Himalayan ecosystem is contributing much to them. Biodiversity is used variously for fodder, fuel wood, timber, leaf litter for manuring crop fields, construction, industrial raw material and several non-timber forests produce. Forests of this region are mainly dominated by Pinus roxburghii Sarg.(Chir Pine) and Quercus leucotrichophora A. Camus. (Banj oak). Chir pine often forms a pure crop in this area but, sometimes it also mixes with certain broad leaved species like Q. leucotrichophora , Quercus glauca Thumb, Pyrus pasia Ham., Myrica eaculanta Linn. and Rhododendron arborium Sm. Saxena et al. (1984) have reported that Q. leucotrichophora prefers cooler aspects below 1900m a.s.l. In the recent years, due to heavy biotic pressure on Q. leucotrichophora forests, P. roxburghii has intruded these forests.

The increasing population trend over the last few decades and consequent dependence on plant products has led to the vast exploitation of natural flora and fauna of this region. The accelerating effects of human activities on biodiversity might impact ecosystem functioning. This has renewed interest in the effect of diversity on ecosystem process (Schulze and Mooney 1993) and on ecosystem services essential to society (Daily 1997). Changes in the landuse, habitat fragmentation, nutrient enrichment and environmental stress often lead to reduced plant biodiversity in natural ecosystem (Mooney et al. 1996, Chapin et al. 1997, Vitousek et al. 1997). In the wake of efficient socio-economic development and for the betterment of soil, livestock and human, the conservation of biodiversity in the Himalaya is assumed to be of great significance. Large number of studies had been made on the different aspects of these forests. Dhar (1997), Silori (2001), Kumar (2000) and Khera et al. (2001) have studied the biodiversity of these forests. The present study deals with species richness and plant diversity in different forest types of Uttaranchal Central Himalaya.

Study area

The study area is located between 79⁰ 23^/and79⁰ 42^/E and 29⁰ 20^/ and 29⁰ 30^/ N between 1300- 2600m a.s.l. in Uttaranchal central Himalaya. The dominant tree species in lower elevation are P. roxburghii and Q. leucotrichophora while Quercus floribunda Lindl., Q. semecarpifolia Sm., Cupressus torulosa Loud. and Cedrus deodara Don. on higher elevations. The climate of the entire study area is influenced by monsoon pattern of rainfall. Generally, the average annual rainfall ranges between 200 -300 cm of which three fourth occurs in the rainy season (mid June to mid September). The mean monthly minimum temperature ranges between 2.0 ⁰C (January) to 15.0 ⁰C (July) and mean maximum temperature ranges between 4.0 ⁰C (January) and 28.0 ⁰C (May). The rocks of the study area are complex mixtures of mainly sedimentary, low-grade metamorphosed and igneous rocks (Valdiya 1980).

Methods

The study was conducted in six dominant forest types of Uttaranchal Himalaya. Each forest type is named after the dominant tree species (Kumar 2000). The size and number of the samples were determined following Saxena and Singh (1982). Species composition for trees, shrubs and herbs was prepared after thorough survey of different forests. Within each forest type all the vegetation layers i.e. trees, shrubs and herbs were analyzed for species richness and diversity. The tree canopy cover was measured by placing ten transects of 400 m² randomly in each forest. Shrub cover was measured as length x width of the crown. Herbaceous cover was determined by line intercept method (Mishra 1968). Trees were analyzed in ten 100 m²_, shrubs in 25 m² and herbs in 1m² plots randomly at each forest. The herbs were analyzed during peak growing season. Plants were identified with the help of plant taxonomist and the flora of Osmaston (1926), Collett (1971), and Kanjilal (1979) were also consulted.

Species richness was determined as the number of species per unit area (Whittakar 1972,1975). Species diversity was calculated by using Shannon-Wiener information index (Shannon and Weaver 1963) as:

H= -(ni/n) log ₂(ni/n)

where, ni is the total number of individuals of a species and n is the total number of individuals of all species.

Species richness was analyzed for single factors Analysis of Variance (ANOVA) following Steel and Torrie (1981). Linear correlation was developed for forest types and tree cover, tree cover and species richness. Correlation coefficient was also determined for various richness and diversity parameters.

Result

A total of 132 species were recorded from the study area, out of which 22 were tree, 43 shrub and 67 herbs. Highest tree diversity 13 was found in P. roxburghii -mixed broad leaf forest and single dominant tree species was in pure P. roxburghii forest. Maximum shrubs richness was 27 and 47 herbs were present inP. roxburghii -mixed broadleaf forest and minimum in Q. semecarpifolia forest (9 shrubs and 13 herbs). Among tree species Q. leucotrichophora was widely distributed and present in all the forest types except inQ. semecarpifolia forest. Similarly, Pyracanthacrenulata M. Roemer, a shrub was present in all the forests except in Q. semecarpifolia forest. Anaphalis contorta Hook. f, an erect herb, and Chrysopogon serrulatus , a grass, showed their presence in all the forest types.

The highest tree mean species richness (100 m²) was found in Q. leucotrichophora forest, whereas the highest shrub mean species richness (in 25 m²) was in P. roxburghii- mixed broad leaf forest. Highest herbs mean species richness (1 m²) in P. roxburghii -mixed broadleaf forest and Cupressus-Quercus forest. Analysis of variance (ANOVA) indicated that the tree mean species richness was significantly higher (p<0.01) in P. roxburghii -mixed broadleaf forests and Q. leucotrichophora forest compared to Q. floribunda andQ. semecarpifolia forests. Shrub mean species richness was significantly higher (p<0.05) in P. roxburghii -mixed broadleaf forest and Cupressus-Quercus forest compared to other forest types. Herbs mean species richness was significantly lower (p<0.01) in Q. semecarpifolia forest. The overall total and mean species richness was lowest in Q. semecarpifolia forest (Table 1). There was no significant relationship in total tree and shrub species richness and forest types but the total herb richness was negatively related (r = -0.589, p<0.05) with forest types. This indicated that the P. roxburghiiand Q. semecarpifolia forest have lowest herb richness compared to other forest types. The total tree species richness was positively correlated (p<0.01) with shrubs and herbs. Similarly, the total shrub species richness was positively related (p<0.01) with herb richness.

Tree cover was significantly correlated (p<0.01) with forest types (Figure 1). Total shrubs and herbs species richness significantly decreased (p<0.01) with increasing tree cover (Figure 2). Q. floribunda and Q. semecarpifolia forest had the highest tree crown cover while P. roxburghii- mixed broadleaf forest had the lowest. Shrub cover significantly decreased (r = -0.733, p<0.01) with increasing tree cover. Tree species diversity was positively correlated with shrub diversity (r = 0.807, p<0.01) and herb diversity (r = 0.688, p<0.05).

Discussion

The forest biodiversity is the main source of livelihood of the people living in the Uttaranchal, central Himalaya. Agriculture is the main occupation around which all the human activities are centered. Agriculture is mainly managed at the cost of surrounding natural forests. Forests present around the crop fields are highly degraded due to continuous anthropogenic disturbances. Thus, the biodiversity of these forests is under great anthropogenic pressure.

There was a significant difference in plant species richness in different forest types. P. roxburghii -mixed broad leaf forest had the highest mean species richness and Q. semecarpifolia had lowest. P. roxburghii -mixed broadleaf forest is present around the crop fields in mid -elevation and have the highest anthropogenic disturbances. Q. semecarpifolia forest is situated on the higher elevations and has least anthropogenic disturbances. Rathore (1993) has also noted high species richness and diversity in the chirpine - mixed broadleaf forest. Singh et al. (1994) have stated that P. roxburghii -mixed broadleaf forest had the highest richness, while pure P. roxburghii and high elevation forest had the lowest. Disturbances promote undergrowth species diversity, possibly by allowing several species to maintain their population in open canopy. More penetration of light in open- canopied forest may enable each species to develop large population, and large population may be less vulnerable to local extinction.

The tree crown cover was lowest in P. roxburghii -mixed broadleaf forest and maximum in Q. floribunda and Q. semecarpifolia forest. The shrub cover decreased with increasing tree cover while there is no relationship between tree and herb cover. The total species richness decreased for tree, shrub and herb with increasing tree cover. Collins and Pickett (1987) reported that canopy disturbance frequently enhances plant biodiversity. This enhanced biodiversity could be related to environmental heterogeneity in the form of patchy light availability (Bellingham et al. 1996), spatial heterogeneity in soil resources (Borann et al. 1995, Denslaw et al. 1998) and local deposition of fallen trees (Everham & Brokaw 1996). Alternatively, the increased diversity could be caused by addition of colonizing species to a disturbed community, regardless of environmental heterogeneity- as long as the number of colonizing species exceeds the number of species lost to the disturbance (Palmer et al. 2000). The forest will be less protective if the canopy is concentrated only at the top. However, if the top layer trees are supported by deep and dense canopies in lower strata, the vegetation will be more protective (Singh & Singh 1986).

Thus, the anthropogenic disturbances play an important role in change, loss or maintaining the plant biodiversity of a region. The low to mid Himalayan forests witnesses human disturbances which is also a major source of livelihood of the people. The forest provides fuel wood, fodder for the domestic animals, timber for house construction, industrial raw materials and other purposes, leaf litter for animal bedding and crop manuring, edible fruits, fiber, gum, resin, dyes, tannin, spices, and more importantly the medicines. Apart from these, some indirect benefits like protection of soil and nutrient, conservation of water and influence on the climate of whole of the northern India and Asia are also the characteristics features of the Himalayan forests.

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Figure 1. Relationship between forest types and tree crown covers in forest of Uttaranchal Central Himalaya.

Figure 2. Relationship between tree cover and shrub & herb diversity in forest of Uttaranchal Central Himalaya.

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