Resource allocation in two selected Carex species along climate gradients

Abstract

Climate will change and is already changing and all organisms are going to react to it, as it is a limiting factor to their lives. To be able to have an idea how plants might respond to climate change, it is important to understand how they respond to current climate. Patterns of growth, allocation and germination in correlation with temperature and precipitation were investigated in a species pair of Carex along a climate gradient in western Noway. The aim was to find similarities and differences in growth patterns and allocation strategies between an alpine specialist, C. capillaris and a lowland generalist, C. pallescens, species. The species were collected as a whole (above ground parts and root system) at eight different sites within the climate grid, plant parts were subsequently measured and weighed. Seeds were counted, weighed and, from C. pallescens, used further in a germination experiment. The two species reacted very differently to climatic variables in respect of growth. While C. pallescens showed a strong positive response to higher temperature in several growth traits, C. capillaris was not found to show any significant reaction to temperature. The increase of precipitation provoked negative reactions in both species, in the case of C. capillaris concerning plant size as leaves grow shorter, in C. pallescens concerning lower seed production. Neither with temperature nor precipitation specific allocation patterns became evident for either of the species. Germination of seeds of C. pallescens from sites with different climate showed strong differences in percentage and patterns. Precipitation has an overall negative effect on germination, whereas temperature has a positive effect on germination percentage and makes seeds germinate faster, but slow down after a while. Increasing seed mass also has a positive effect on germination, but precipitation together with seed mass still shows a negative germination effect. In the context of climate change this might lead to a disadvantage in competition for C. capillaris, as bigger growing plants might outcompete a smaller species. For C. pallescens an overall negative reaction in reproductive traits to higher precipitation may be the effect that could lead to an overall diminished success in wetter areas.