Purpose

The main objective of this research was to examine the effects of inter-annual water regime variation on soil and plant characteristics, and soil–vegetation relationship at the lakeshore wetland of Poyang Lake, China.

Materials and methods

Six transects which paralleled the lakeshore were established at a typical Carex lakeshore wetland of Poyang Lake. We performed the field investigation and sampling in the autumn growing seasons in a flooding year (2017) and a drought year (2018). Paired t test was carried out to determine the effects of inter-annual water regime variation on various soil and plant parameters. Redundancy analysis was used to examine the relationships of plant species composition with flooding and soil variables in both years.

Results and discussion

Soil water content (SW), soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), the ratio of SOC to TP (C/P ratio), the ratio of TN to TP (N/P ratio), ammonia nitrogen concentration (NH₄-N), and nitrate nitrogen concentration (NO₃-N) were 21 ~ 71% higher in the flooding year than in the drought year. Plant Shannon–Wiener indices were significantly lower in the drought year than in the flooding year, whereas aboveground and belowground plant biomass showed opposite patterns. Flooding and soil variables could strongly determine plant communities in both years. Flooding duration was the most important variable among all flooding and soil variables. After eliminating the effects of flooding duration, pH and SW still significantly affected plant community composition in the flooding year, while only NH₄-N significantly impacted on plant species distribution in the drought year.

Conclusions

The results provided direct evidences that the inter-annual water regime variation not only could dramatically modify soil and plant variables but also could change the soil–vegetation relationship in the wetlands. Our studies have great implications for the conservation and restoration of the wetlands, especially for the lake wetlands in the middle and lower reaches of Yangtze River.

中文翻译：

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Po阳湖湖滨湿地两个水文对比年中的土壤和植物特征

目的

这项研究的主要目的是研究of阳湖湖岸湿地年际水情变化对土壤和植物特征的影响以及土壤与植被的关系。

材料和方法

在Po阳湖典型的Carex湖岸湿地上建立了六个与湖岸平行的样带。我们在洪水年（2017）和干旱年（2018）的秋季生长季节进行了田野调查和采样。进行配对t检验，以确定年际水态变化对各种土壤和植物参数的影响。冗余分析用于检查两年中植物物种组成与洪水和土壤变量之间的关系。

结果和讨论

土壤水分（SW），土壤有机碳（SOC），总氮（TN），总磷（TP），SOC与TP之比（C / P比），TN与TP之比（N / P比） ），氨氮浓度（NH ₄ -N）和硝酸盐氮浓度（NO ₃-N）在洪水年度比干旱年份高21〜71％。干旱年份的植物香农-维纳指数显着低于洪水年份，而地上和地下植物生物量显示出相反的模式。在这两年中，洪水和土壤变量都可能强烈决定植物群落。洪水持续时间是所有洪水和土壤变量中最重要的变量。在消除了洪水持续时间的影响之后，pH和SW在洪水年度仍显着影响植物群落组成，而在干旱年份仅NH ₄ -N显着影响植物物种分布。

结论

结果提供了直接的证据，表明年际水态变化不仅可以显着改变土壤和植物的变量，而且可以改变湿地的土壤－植被关系。我们的研究对湿地的保护和恢复具有重要意义，特别是对于长江中下游的湖泊湿地。