Interannual variability of seasonal succession events in a temperate lake and its relation to temperature variability

摘要

The assessment of possible implications of anthropogenic climate change requires the evaluation of results obtained with complex mathematical climate models. In this paper we consider the problem of assessing the impact of climate variability on succession events between January and May in a lake (Plusssee) of the temperature region. Whereas the climate model output generate unable information only on the large scales of hundreds of kilometers at best, the impact of climate occurs on smaller scales. Thus we first established a statistical link between large-scale air temperature, at about 1500 m height, and the local temperature to bridge the spatial gap of global climate models and local climate which forces processes in the lake. In a second step the local temperatures were statistically related to biologically induced dynamic features in the lake. These features were accomplished taking secchi depth readings as integrated measures. In addition the observed relationships were compared with features from a dynamic model with phyto- and zooplankton as functional units, running under different temperature regimes. The local temperatures approximated closely the large-scale temperature. The timing of phyto- and zooplankton maxima (clearwater phase) were negatively related to the temperature. Thus with a temperature increase both occured earlier. The intensity of the spring algal maximum was negatively related to its timing, whereas no clear relation between the timing and intensity of the clearwater phase (zooplankton maximum) could be obtained. (orig.)