鄱阳湖湿地灰化苔草种群生产力特征及其水文响应

Productivity of Carex cinerascens population and its response to hydrological conditions in the Poyang Lake wetland

淡水湖泊湿地中,水文条件是影响湿地植物分布和生长发育的关键因素,研究特定湿地植物种群与水文变化之间关系,对于认识湿地植被格局形成及进行湿地生态调控与恢复具有重要意义。选取鄱阳湖湿地洲滩优势植物——灰化苔草(Carex cinerascens)种群作为研究对象,基于野外实地观测数据,研究不同高程带灰化苔草春草种群生产力特征及其对水文变化的响应。结果表明:春草生长季内各高程带灰化苔草种群变化规律基本一致,但其生长发育过程对水文条件产生差异性反应,长期连续水淹和半水淹条件抑制灰化苔草的生长,而间歇性半水淹和未水淹条件则促进灰化苔草伸长生长和生物量积累;生长初期灰化苔草通过储水策略应对水分缺乏形成的干旱胁迫,而生长末期则通过增加干物质含量来应对淹水胁迫;灰化苔草定植与生长发育需要一定的水文条件,淹没期平均水深3.70—2.78 m、淹没频率42.08%—43.17%、平均距湖水面高度-0.23—0.77 m的水文环境更有利于灰化苔草的生长发育。研究结果可为未来鄱阳湖湿地植被保护和湖泊水位调控提供重要参考依据。

In freshwater lake wetland ecosystems, hydrological conditions are the key factors affecting the distribution of vegetation and plant growth. It is of great importance to elucidate the relationships between plants and hydrological conditions to understand the formation of wetland vegetation patterns and provide appropriate references for ecological regulation and wetland ecosystem restoration. This study was conducted using field surveys on the height, density, and biomass of a Carex cinerascens population along an elevation gradient in Poyang Lake wetland to assess the variation in productivity of the C. cinerascens population during the spring growth season and its response to hydrological conditions. The results showed that the ecological indicators of the C. cinerascens population presented the same trends in different elevation zones during the spring growth season, whereas the spatial heterogeneity of hydrological conditions had an obvious effect on the growth of the C. cinerascens population. It was confirmed that long-term continuous flooded and semi-flooded conditions severely inhibited the growth of the C. cinerascens population and caused C. cinerascens to undergo quiescence syndrome of dormancy or slow growth. The intermittent semi-flooded and non-flooded conditions can promote the growth and biomass accumulation of C. cinerascens, which usually adjusted its water use strategy in different growth stages according to the field hydrological conditions. In the early growth stage, C. cinerascens responded to drought stress by increasing the water content of the plant, whereas it accumulated dry matter in the late growth stage during flooding stress. In addition, hydrological conditions greatly affected the colonization and growth of C. cinerascens. During the two adjacent spring growth seasons, C. cinerascens could benefit from hydrological conditions with average inundation water depth of 2.78-3.93 m, inundation frequency of 42.10%-60.38%, and the water height from the water surface of -1.73-0.77 m. Hydrological conditions with an average inundation water depth of 3.70-2.78 m, inundation frequency of 42.08%-43.17%, and average height from the water surface of -0.23-0.77 m were more conducive to the growth of C. cinerascens. These results could provide an important reference for wetland vegetation protection and water level regulation in the Poyang Lake wetland.