Oscillating vegetation dynamics in a wet heathland

Abstract

Abstract. Question: The significance of disturbances caused by periodical inundation was investigated with respect to its effects on vegetation dynamics, species richness and fluctuations, and to the relevance of certain plant properties. Location and Method: At a sod‐cut stand within nutrient‐poor inland sand dunes, permanent plots along a transect were surveyed over a period of up to nine years after sod cutting. Results: In contrast to never inundated plots, periodically inundated plots were characterized by low vegetation cover and by high numbers of species belonging to many different communities, each of them with a low cover. Periodical inundations favoured the presence of pioneers, species tolerant of disturbances, species adapted to wet conditions and stoloni‐ferous species. Furthermore, annual fluctuations of species within each plot were higher and most species occurred only sporadically. Discussion: A comprehensive model is presented describing the relevant processes identified in the littoral zone. Changing water tables result in the creation of gaps. The re‐colonization of these gaps follows mainly from vegetative regeneration and less to the dispersion of diaspores. Highest species numbers in the zone of moderate disturbances result from a high rate of re‐colonization in spite of local extinctions following each disturbance event. It is suggested that colonization abilities are among the most important features for species occurrence at a site rich in disturbances (more important than competitive abilities and more important than a slow rate of displacement). For nature conservation such sites are very important, because they allow (rare) pioneer species to survive for longer periods of time.

Modeling the Spatial Distribution of Three Typical Dominant Wetland Vegetation Species’ Response to the Hydrological Gradient in a Ramsar Wetland, Honghe National Nature Reserve, Northeast China

“…The hydrological regime in wetlands is strongly correlated with the elevation of the ground surface and the water depth [40]. If the water level exceeds a certain elevation, the vegetation at this elevation is considered to be submerged.…”

Trade-off between allocation to reproductive ramets and rhizome buds in Carex brevicuspis populations along a small-scale elevational gradient

“…It reproduces sexually through seeds and asexually via rhizome buds 21 22 . In freshwater wetlands or floodplains, the elevation, which closely reflects the hydrological and edaphic conditions at which plants occur, is the most important factor affecting plant growth, reproduction, and distribution 20 23 24 25 26 . For wetland sedges, low-elevation sites may represent harsh conditions for plant growth and reproduction due to the longer duration of flooding submergence and the irregular flooding during the growing season 20 27 .…”

Marshland vegetation of the class Phagmito-Magnocaricetea in Croatia

“…According to Pickett & White (1985) and Urban (2005) a very important role in the dynamics of marshland vegetation is played by flooding which, as a disturbance factor, enables the maintenance of pioneer marshland plant species and communities. Flooding also plays a role as a means of distribution of plants' propagules (Cellot et al 1998).…”