Expansion of water chestnut in a small dam reservoir: from pioneering colony to dense floating mat

Abstract

Background and Purpose: This manuscript reports on the rapid spread of water chestnut in a shallow dam reservoir. The water chestnut is a critically endangered plant in Poland.

Materials and Methods: From 2008 to 2016 during the vegetation season we investigated the distribution of water chestnut in the Rzeszów dam reservoir.

Results: The colony has grown from sparse individual plants which probably appeared around 2005, to a dense floating mat of plants with the total area of over 14 ha today. Recently water chestnut has also appeared in all shallow parts of the reservoir with weak water flow.

Conclusions: Taking into consideration the dynamic expansion of the water chestnut, it can be assumed that in the near future this species may control many parts of the Rzeszów reservoir, while in others it can be displaced by reeds. It is highly probable then that the total area of water chestnut patches will decrease, rather than increase.