Distribution of Triarrhena lutarioriparia and its reserve characteristics of nitrogen and phosphorus in Dongting Lake

Abstract

Triarrhena lutarioriparia, a typical and most abundant macrophyte in Dongting lake wetland, was in the state of abandonment following the papermaking industry revocation in the lake basin. In order to provide scientific basis for precise management of T. lutarioriparia, the T. lutarioriparia distribution charateristics in Dongting Lake and its storage characteristics of nutrients were investigated in this study. Remote sensing interpretation results showed that the total area of T. lutarioriparia in Dongting Lake wetland was 58, 450 ha, 48.31% of which distributed in South Doting Lake wetlands. The nutrients contents were significantly different in T. lutarioriparia tissues, ranking in the descending order of spikes (TN 27.90 mg/g, TP 3.46 mg/g)>leaves (TN 16.38 mg/g, TP 2.11 mg/g)>stems (TN 5.38 mg/g, TP 0.85 mg/g). The total P quantities in each T. lutarioriparia tissue were ranked in the order: stems (560.26 t)>leaves (396.52 t)>spikes (284.67 t), while the total N quantities were within the range of 2170.02-2801.3 t. It was estimated that about 7712.99 t of TN and 1241.45 t of TP were annually removed from Dongting Lake by reaping T. lutarioriparia. The nutrients stored in the dead tissues of T. lutarioriparia might possess non-negligible impact on the water quality of Doting Lake.