Clonal fragmentation drives performance deterioration of epiphytic and lithophytic ferns in a karst forest

Abstract

Clonal plants can regenerate after being fragmented by natural or artificial disturbances, which may be attributed to physiological integration. Both lithophytes and epiphytes are important ecotypes of clonal plants. However, few studies have compared the responses of lithophytes and epiphytes to clonal fragmentation. Focusing on this issue could help us to understand the regeneration potential of clonal plants in different habitats, and to know more about the environmental adaptation of the two ecotypes. Two clonal ferns Pyrrosia nummulariifolia (Sw.) Ching and Lemmaphyllum microphyllum C. Presl, living in two ecotypes (lithophytes and epiphytes) of a tropical karst forest, were tested for the survival, biomass, the maximum quantum yield of photosystem Ⅱ (Fv/Fm), and leaf length of clonal plants in response to clonal fragmentation. Fragmentation had a significantly negative effect on the survival rate and biomass of clonal plants. However, ecotypes showed few effects on the performance of both clonal ferns in response to the fragmentation of different levels, suggesting that both epiphytes and lithophytes were equally susceptible to clonal fragmentation, probably because they were equivalently living in harsh and heterogeneous habitats. Further, decreasing clonal fragmentation and increasing ramet developmental age had positive effects on ramet survival, biomass, stress resistance, and leaf length. The effects of fragmentation level depended on ramet age. The results reveal that fragmentation has negative effects on the performance of clonal plants, especially juveniles and small ones. For better management of karst forests, disturbances should be avoided as much as possible to allow the growth and regeneration of clonal plants.