The relationship between some morphological and chemical features of Sphagnum cuspidatum Ehrh. and physical characteristics of the environment

Abstract

SummaryThe frequency (No. 1000 fascicles−1) of innovations (branches resembling the parent shoot) on plants of Sphagnum cuspidatum Ehrh. was determined at IX sites on or near the Silver Flowe National Nature Reserve on six occasions. The capitula were analysed for nitrogen, phosphorus and potassium.When the sites were arranged in order of increasing mean innovation frequency it was found that the frequency at ombrotrophic sites was less than that at rheotropic sites. Interfascicle length was directly related to innovation frequency but no evidence of a relationship between either interfascicle length or innovation frequency and capitulum dry weight was found. During the course of each growing season the variances of the means of interfascicle length and capitulum dry weight declined.Multiple regression analysis indicated that the capitulum dry weight and interfascicle length were negatively and positively related respectively to the nitrogen content of the capitula. The regression of innovation frequency on N, P and K in the capitula was not significant (P > 0.05).Two experiments were undertaken in which shoots of Sphagnum cuspidatum were reciprocally transplanted between a rheotrophic and an ombrotrophic site. During the course of a single growing season the mean interfascicle length, the mean capitulum dry weight and the mean concentrations of N, P and K in the capitula became much more similar to those of the controls. At the beginning of each experiment all visible innovations were removed from the plants. At the end of the experiment in 1983 innovation frequencies on the transplants were intermediate between those on the ombrotrophic and rheotrophic controls. In 1984 innovation frequencies on both controls and transplants were relatively low and an attempt is made to explain this in terms of the climatic conditions of that year.