A Comparative Study of Leaf Demography in Limestone Grassland

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Abstract
Leaf demography was studied to investigate seasonal changes in shoot biomass within a community of grassland plants. The appearance and death of leaves and the changes in length of the live portions of leaves were recorded on marked shoots of 20 plants from each of 10 spp. at regular intervals over a 14-mo. period. Survivorship curves and half-lives for cohorts of leaves are presented along with diagrams describing the age-structure of leaf populations at intervals throughout the year. The time of leaf production and longevity differed between species. Anthoxanthum odoratum had a few leaves which survived for 90 days; no cohort of Carex flacca appeared to have a half-life of less than 420 days. Most species followed the same pattern, with a high production of short-lived leaves in the spring or early summer and fewer longer-lived leaves appearing in the autumn. The time of greatest leaf mortality corresponded to the period of rapid growth and new leaf production. The time of leaf production and longevity within individual species corresponded to and amplified the existing phenological data. The demography results also substantiated the previously proposed classification of species into phenological types. No 2 spp. showed the same combination of the attributes investigated. The observed spatial and temporal differences in the leaf populations of the apparently coexisting species can be used to manipulate artificially the species diversity in a predictable and controlled manner.