• S P Singh

      Articles written in Proceedings – Plant Sciences

    • Seed germination ofQuercus leucotrichophora A. Camus. ex. Bahadur andPinus roxburghii Sarg. on certain single factor environmental gradients

      P B Rao P K Ralhan S P Singh

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      The seed dry weight ofQuercus leucotrichophora A. Camus. ex. Bahadur (banj oak) were much larger than the seeds ofPinus roxburghii Sarg. (chir pine) (1463 and 87 mg per seed). The responses of chir pine, an early successional species, and banj oak, a late successional species were compared in terms of seed germination. Seed germination was observed on single factor gradients of temperature, water stress, seed desiccation and light qualities. The suppression of germination caused by continuous dark and far-red was greater for chir pine than in banj oak. Compared with banj oak, chir pine seed germination showed wider response breadth on gradients of water stress and seed desiccation and narrower response breadth on the gradient of light quality.

    • Structure and function of the Central Himalayan oak forests

      S P Singh J S Singh

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      Oak (Quercus spp.) forests represent the climax evergreen vegetation between 1000–3600 m in the Central Himalaya. Shrub layer is well developed in these forests and phanerophytes prevail (50–60%). Though one oak species mixes frequently with other oak species, or conifers, the single-species dominance is quite common. All the oak forests are vulnerable to fire. They support a great variety of wildlife. Coppicing subsequent to cutting is well developed in all oak species and helps them in regeneration. However, because of severe biotic stress oaks are failing to regenerate in forest stands. The forest biomass ranges between 294–787 t ha−1 and the net primary productivity generally between 16–21 t ha−1 yr−1. Oak forests store a large proportion of their nutrients in biomass component. Leaves are nutrient-rich and decompose rapidly. Evergreen woody species with concentrated summer leaf drop prevail in oak forests. The seasonality of the ecosystem activities seem to be influenced by the monsoon pattern of rainfall. Though the recovery is rapid after the forest destruction, because of continuous and severe biotic stress, oaks are being replaced with other communities.

    • Population structure of tree species in forests as an indicator of regeneration and future stability

      S P Singh J C Tewari S Yadav P K Ralhan

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      The size class distribution in tree populations will continue to be used for analysing the regeneration of tree species and successional patterns in forest communities at extensive levels. However, information regarding the approximate estimates of lifetime expectancy (residence time) for each of the size classes, viz seedlings, saplings and trees, and the estimates of rate of net gain for them (population divided by residence time) can considerably enhance our understanding of the regeneration trends of species. It is shown that several population structures, based on size class distribution may indicate declining population trend, although the population, as indicated by rate of net gain parameter, in fact may foretell future expansion or stability. It appears that high species richness and high percentages of species with poor regeneration are interrelated with each other.

    • Biomass structure and net primary production of Siwalik chir pine (Pinus roxburghii Sarg.)-mixed broadleaf forest

      B S Rana S P Singh R P Singh

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      Biomass and net primary production of chir pine (Pinus roxburghii Sarg.)-mixed broadleaf forest is described. The total forest biomass (about 199 t ha−1) and net primary production (12·4 t ha−1 yr−1) did not reveal marked differences from similar aged central Himalayan chir pine forests. Trees accounted for most of the biomass and net primary production.

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