Seasonal Changes in Leaf Area Index and Chlorophyll in an Indian Grassland

Abstract

SUMMARY (1) Seasonal variation in the leaf area index in grassland at Berhampur, India, showed a minimum of 0 5 in March and a maximum of 5.0 in late September. For most species, the maximum occurred between July and November. (2) There were seasonal changes in chlorophyll concentration, with maximum per unit dry weight of plant of 3 5 mg g-' in late August and maximum per unit area of 1.2 g m-2 in late September. Newbould (1967) and Milner & Hughes (1968) recommended that the estimation of chlorophyll concentration and leaf area indices should be utilized in all International Biological Programme projects as quantitative measures of the photosynthetic system. Although stems, petioles, leaf-sheaths and a few other green organs of plants show some light interception, which may be very important at certain times of the year, leaves are the main organs for photosynthesis and community production. Watson (1947) formulated the concept of leaf-area index (LAI) which is the quotient of the total leaf area (one surface only) divided by the total ground area. The community chlorophyll concentration per unit area was cited by Odum (1971) as an example of 'community homeostasis'. Several ecological processes, particularly (primary) production, are influenced by the amount of leaf area and the chlorophyll concentration (Brougham 1960; Bray 1960; Black 1963; Bliss 1966, 1970; Ovington & Lawrence 1967; Knight 1973; Mall & Billore 1974; Misra & Mall 1975; Billore & Mall 1975; Redmann 1975). This paper describes an attempt to evaluate the magnitude of the seasonal changes in LAI and chlorophyll concentration in terms of both dry weight of plant material and of ground area in a grassland community.