Share of rushes in water uptake in shallow lakes in eastern Poland

The intensity of transpiration depends on many environmental factors including light, temperature, wind, and air humidity. By eliminating the variation of these factors under laboratory conditions, an attempt was made to indicate the intensity of this process among different species of helophytes and are there any factors limiting this process. We performed a field study of some shallow lakes to answer the question: what is the role of emergent macrophytes in evapotranspiration in lakes with different trophy and surface. Field works were carried out in the shallow littoral at the peak of the growing season. Under laboratory conditions five species were analysing in respect of water uptake. Under laboratory conditions, the width, length and number of leaves as well as the mass and diameter of the stems of respective species had the most significant effect on the uptake of water by helophytes. The length of the plant was a characteristic with the least significant impact on water uptake. The presence of inflorescence was highly negatively correlated with the amount of water taken up by the plants. This phenomenon may slow down the process of water uptake by plants. Among the analyzed factors affecting the uptake of water in the shallow lakes of the Łęczna-Włodawa Lake District, the most important effect was the area of rushes, their density and lake trophic type. In contrast, the type of lake supply, surface of the lake and the variety of helophytes proved to be irrelevant to the amount of water uptake. Helophytes play a significant role in the uptake of water. The share of Typha rushes significantly increases transpiration.We analyzed the impact of various factors on the transpiration process of selected species of emerged macrophytes in laboratory and field conditions. We showed what factors can increase or decrease this process and how important are helophytes in the lake's water balance