© 2018 JETIR May 2018, Volume 5, Issue 5 www.jetir.org (ISSN-2349-5162) JETIR1805738 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 804 Study of the life form and the biological spectrum of Umananda River Island, Guwahati, Assam, India - a tool for characterization of the phytoclimate Pranab Bujarbarua Assistant Professor Department of Botany Handique Girls’ College, Guwahati, India Abstract: The present paper deals with the characterization of the phytoclimate of the Umananda river island in Guwahati, Assam with the help of Raunkiaer’s life form and biological spectrum method. A total of 128 species of vascular plants belonging to 122 genera and 60 families have been reported from the island. All the plant species are categorized into different life form based on the position of their perennating bud. Therophytes (Th. = 32.03%) and Mesophanerophytes (Mesoph. = 20.31%) were found to be dominant followed by Chamaephyte (Ch. = 11.72%), Microphanerophyte (Microph. = 9.38%), Hemicryptophytes (H.Cr. = 7.03%), Lianas/climbers and Geophytes (5.47%), Mega and Nanophanerophyte (3.13%) and Epiphytes (2.34%). On the basis of the life form categories, biological spectrum was prepared and compared with Raunkiaer’s normal biological spectrum. On comparisons with Raunkiaer’s normal spectrum, the area depicts Thero-phanerophytic type of phytoclimate. Key words: Life form and biological spectrum, Phytoclimate, Umananda river island. I. INTRODUCTION The classification of plants on the basis of similarities in structure and functions is called life form or growth form and the plant climate of a region is characterized by the life form (or forms). Life form portrays the plant adaptation to certain ecological conditions (Meera et al., 1999) and is an important physiognomic attributes that have been widely used in vegetation studies. The concept of life form in the study of vegetation and groupings of vegetation type on the physiognomic basis dated back to the period of Humbolt (1806). A biological spectrum could be formed by categorizing all the species of the higher plants of the community into various life forms and their ratio is expressed as percentage value. In other words, the statistical distribution of the life forms in the flora of a region is expressed in the form of biological spectrum. The biological spectrum reflects the adaptation of plant to environment and primarily climate (Smith, 1980). Since the life forms are related to the environment around the plants, biological spectrum is also regarded as indicative of the prevailing environment (Meher-Homiji, 1981). Raunkiaer (1934) considered the position of regenerating parts as the most important criterion for life-form system of classification of plants. Depending on this single character, he classified the higher plants into five major categories viz. Phanerophytes (Ph), Chamaephytes (Ch), Hemicryptophytes (HCr), Geophytes (G), and Therophytes (Th). The life-forms are taken as indicator of climate and on the basis of the life-form composition. Raunkiaer recognized three main types of phytoclimate on the earth viz., phanerophytic climate in the tropics, therophytic climate in the desert, and hemicryptophytic climate in the greater part of the cold temperate zone. Raunkiaer’s normal spectrum indicates a phanerophytic community for the world and the deviation from it determines the phytoclimate of the habitat. Raunkiaer’s life-form spectrum was modified by Braun-Blanquet (1951) and Ellenberg and Mueller-Dombois (1974). Meher- Homiji (1964, 1981) has recognized ten phyto-climatic regions in India. In the present study, attempt has been made to characterize the phytoclimate of Umananda River Island near Guwahati in the state of Assam with the help of life form and the biological spectrum systems of Raunkiaer. The life form system of categorising plants is based primarily on the methods, by which plants survive the unfavourable season. The proportions of the flora in the various categories i.e. the biological spectrum vary from one climate to another. II. OBJECTIVES Plant life form method of vegetation analysis is useful in delineating the phytoclimatic type, particularly in areas that are relatively less disturbed. The present study has been formulated to study the life form and biological spectrum of the flora Umananda river Island - a small island of 4.9 ha in the Brahmaputra river near Guwahati, Assam. Along with recording the life form categories of the plant taxa, attempts are also being made to classify the plants as per the Raunkiaer’s life form classification and calculate the biological spectrum that would enabl e to understand the community structure and adaptation of the plant to the climate of the Island. Raunkiaer (1934) constructed a ‘normal spectrum’ from the life form categories which could act as null model and different life form spectra could be compared with this. This system is an early and undoubtedly still useful attempt to relate plant morphology and life history to climate. The biological spectrum not only represents the climatic conditions but is also the most potent environmental factor representing the ecosystem and to understand the community structure and adaptation of the plant to the climate of the area. III. METHODS To study the life forms, several exploration tours to the island have been undertaken during the year 2011 to 2013. Accordingly, the growth form, habit, height and location of the perennating buds of the plant species were recorded and they were grouped into life-forms according to Raunkiaer (1934) and subsequent modification by Braun-Blanquet (1951). Parasites and liana/climbers were put under separate class as done by other workers (Rajendraprasad et al. 1998, Chattopadhyay 1998, Verma & Shukla 1993, Pandey & Parmer 1993 and Sharma & Rajpal 1991). For preparation of biological spectrum, the number of species in each life-form is calculated and the percentage of species belonging to each life-form is determined by following formula –