Human impact on the ecological performance of Potamogeton species in northwestern Germany

Abstract

The changes in habitat quality of lowland rivers in Lower Saxony (Germany) during the past 40 years are outlined. Almost all chemical, physical, and morphological parameters have changed, resulting in most cases in an enhanced potential productivity, accompanied by a complex disturbance regime. Historical reconstruction of the change in river vegetation is presented to compare the frequency of macrophyte species 40 years ago with the situation of today. For a total of 289 sampling sites, the floristic change was exactly reconstructed. Nearly all species show a decline in frequency. This trend is also recognizable in Potamogeton, with the exception of two narrow-leaved species.An attempt is made to explain both decline and maintenance in terms of life history characters (vital attributes) allowing the species to react to the changing habitat conditions. The successful species are characterized by certain life history characteristics which enable them to survive under the current disturbance regime. Most important aspects of life history are the ability to reproduce by means ofturions and other fragments, a long-lived, deep-rooting rhizome system, phenotypic plasticity of above-ground parts, synchronous shoot polymorphism, and the potential to regenerate quickly from remaining buds after disturbance. The decline of formerly frequent species can be attributed mainly to the lack of certain key characters; however, physiological characters also may be important. The extirpation of some rare species could also be caused by random fluctuations in small populations. The general importance of population ecological research, particularly demography, life history theory, and the modelling of clonal populations in conservation ecology is stressed.

Long‐term dynamics of macrophyte dominance and growth‐form types in two north‐west German lowland streams

“…Because the historical reconstruction of river vegetation based on published and unpublished vegetation data was regarded as partly unsatisfactory (see Wiegleb, 1979;Herr, Todeskino & Wiegleb, 1989a;Wiegleb, Brux & Herr, 1991), long-term observation projects were started by Brux et al (1988) and Wiegleb, Herr & Todeskino (1989), covering time series of 9-11 continuous years. Among the long-term observations, the account of Schweinitz et al (2012) is unrivaled, describing repeated sampling of a pre-alpine river over 40 years.…”

Distribution patterns, floristic structure and habitat requirements of the alpine river plant community Stuckenietum amblyphyllae ass. nova (Potametea) in the Pamir Alai Mountains (Tajikistan)

“…But even if there are such plans for the future this activity most likely will take place in the lower sections of the river, where there is no habitat of S. amblyphylla. However, we must bear in mind that in Europe the aquatic communities are quickly disappearing and that they respond very rapidly to all environmental changes caused by anthropogenic pressure [42,[48][49][50].…”

Aquatic vegetation in two pre-alpine lakes of different trophic levels (Lake Bled and Lake Bohinj): vegetation development from the aspect of bioindication

“…Currently, and to mention only some of them, many authors research these relations (Melzer, 1992 ;Lachavanne et al, 1992 ;Blindow, 1992 ;Wiegleb et al, 1991 ;Ozimek et al, 1991 ;Lachavanne et al, 1991, Lachavanne, 1985.…”