模拟水深和氮添加对三江平原湿地植物功能性状的影响

水深和氮素是影响湿地植物生长的关键因素,研究两者对功能性状的影响有助于预测未来环境变化下湿地植物的生长与分布趋势.以三江平原沼泽湿地3种优势植物(漂筏苔草Carex pseudocuraica、毛苔草Carex lasiocarpa和燕子花Iris laevigata)为研究对象,设置3个水深(0、5、15 cm)和3个氮浓度(0、12、36 mmol/L)的双因子控制实验,探讨不同水深和氮添加对3种湿地植物功能性状的影响.结果显示,水深和氮添加对漂筏苔草根冠比和燕子花株高、地下与地上生物量及根冠比存在交互影响.在0 mmol/L氮浓度下,随着水深的增加,漂筏苔草根冠比降低,燕子花根冠比呈先降低后上升的趋势.在12 mmol/L氮浓度下,随着水深的增加,燕子花地下与地上生物量降低,根冠比增加.随着氮浓度的增加,燕子花株高在0、5 cm水深时降低,在15 cm水深时增加.水深对漂筏苔草叶面积、地下与地上生物量和燕子花叶面积有显著影响,随着水深的增加,漂筏苔草叶面积、地下与地上生物量呈先增加后下降的趋势,燕子花叶面积降低.氮添加对毛苔草株高、叶面积及根冠比有显著影响,随着氮浓度的增加,毛苔草株高和叶面积降低,根冠比呈先降低后上升的趋势.本研究表明湿地植物对水深和氮添加水平的响应依赖具体物种和功能性状指标而不同,未来还应加强湿地植物地下性状的研究.(图3表1参56)

Effects of simulated water depth and nitrogen addition on functional traits of wetland plants in Sanjiang Plain

Water depth and nitrogen are the key factors affecting the growth of wetland plants. The studies, which examined their combined effects, can help predict the growth and distribution of wetland plants under future environmental changes. Three dominant plants(Carex pseudocuraica, Carex lasiocarpa, and Iris laevigata) in the marsh wetland of the Sanjiang Plain were used as the experimental organisms. We conducted a two-factor control experiment with three levels of water depth(0, 5, and 15 cm) and three levels of nitrogen concentration(0, 12, and 36 mmol/L) to explore their effects on the functional traits of the three types of wetland plants. Water depth and nitrogen addition have interactive effects on the root : shoot ratio of C. pseudocuraica;and the height, belowground and above-ground biomass, and root : shoot ratio of I. laevigata. At 0 mmol/L nitrogen concentration, the root : shoot ratio of C. pseudocuraica decreased, and the root : shoot ratio of I. laevigata decreased first and then increased with increasing water depth. At a nitrogen concentration of 12 mmol/L, the below-ground and aboveground biomass of I. laevigata decreased, and the root : shoot ratio increased with increasing water depth. With the increase in nitrogen concentration, the height of I. laevigata decreased at water depths of 0 and 5 cm, and increased at a water depth of 15 cm. Water depth has a significant effect on the leaf area, below-ground and above-ground biomass of C. pseudocuraica, and the leaf area of I. laevigata. With increasing water depth, the leaf area, below-ground and above-ground biomass of C. pseudocuraica increased at first and then decreased;the leaf area of I. laevigata decreased. Nitrogen addition has a significant effect on the height, leaf area, and root : shoot ratio of C. lasiocarpa. With increasing nitrogen concentration, the height and leaf area of C. lasiocarpa decreased, and the root : shoot ratio of C. lasiocarpa decreased at first and then increased. The response of wetland plants to water depth and nitrogen addition depended on particular species and their functional traits. Future studies should strengthen the research on the below-ground traits of wetland plants.