Climate change and the future distributions of aquatic macrophytes across boreal catchments

Abstract

Ecological systems are typically hierarchically structured, and local-scale patterns are often constrained by large-scale processes. Processes operating at the regional scale may, for example, override local-scale factors in determining species distributions (Levin, 1992;Cottenie, 2005). Hence, identifying the importance of large-scale processes is also a prerequisite for understanding variation in species distributions at local scales. Large-scale studies of species distributions have been focused ABSTRACT Aim Aquatic-terrestrial ecotones are vulnerable to climate change, and degradation of the emergent aquatic macrophyte zone would have severe ecological consequences for freshwater, wetland and terrestrial ecosystems. Our aim was to uncover future changes in boreal emergent aquatic macrophyte zones by modelling the occurrence and percentage cover of emergent aquatic vegetation under different climate scenarios in Finland by the 2050s.Location Finland, northern Europe.Methods Data derived from different GIS sources were used to estimate future emergent aquatic macrophyte distributions in all catchments in Finland (848 in total). We used generalized additive models (GAM) with a full stepwise selection algorithm and Akaike information criterion to explore the main environmental determinates (climate and geomorphology) of emergent aquatic macrophyte distributions, which were derived from the national subclass of CORINE landcover classification. The accuracy of the distribution models (GAMs) was crossvalidated, using percentage of explained deviance and the area under the curve derived from the receiver-operating characteristic plots. ResultsOur results indicated that emergent aquatic macrophytes will expand their distributions northwards from the current catchments and percentage cover will increase in all of the catchments in all climate scenarios. Growing degree-days was the primary determinant affecting distributions of emergent aquatic macrophytes. Inclusion of geomorphological variables clearly improved model performance in both model exercises compared with pure climate variables.Main conclusions Emergent aquatic macrophyte distributions will expand due to climate change. Many emergent aquatic plant species have already expanded their distributions during the past decades, and this process will continue in the years 2051-80. Emergent aquatic macrophytes pose an increasing overgrowth risk for sensitive macrophyte species in boreal freshwater ecosystems, which should be acknowledged in management and conservation actions. We conclude that predictions based on GIS data can provide useful 'first-filter' estimates of changes in aquatic-terrestrial ecotones.

Geographic patterns of lake macrophyte communities and species richness at regional scale

“…Temperature during the growing season is of great importance for aquatic flora, as also found for boreal emergent macrophytes (Alahuhta et al. 2011a). Netten et al.…”

Development and evaluation of the Finnish fish-based lake classification method

“…This is probably due to the climate-dependent reduction in productivity since total fish biomass in relation to nutrients decreased at higher latitudes. In northern areas, the shorter growing season is limiting the overall productivity of aquatic systems (Alahuhta et al, 2011). Further investigation is needed, whether the RVs and CBs in the Finnish fish-based lake assessment system should be proportioned to latitude effects.…”

Phylogenetic diversity of regional beetle faunas at high latitudes: patterns, drivers and chance along ecological gradients

“…High-latitude regions have experienced and are predicted to experience stronger changes in climate compared to many other regions in the future (Anisimov et al 2007;Lenton et al 2008;Heino et al 2009;Cowie 2013), but little is known how the phylogenetic diversity of insect faunas is associated with changes, variations and extremes in climatic conditions. Furthermore, given that both aquatic and terrestrial vegetation is likely to change profoundly in the face of climate change in high latitudes (Heino et al 2009;Alahuhta et al 2011), many insects associated with terrestrial, semi-aquatic and aquatic habitats will likely respond to those changes rapidly (Hickling et al 2006;Thomas et al 2006). This is because most insects rely on plants either directly as food sources or indirectly as habitat structure provided by vegetation.…”