Nitrogen and phosphorus contents in 44 wetland species from the Lake Erhai Basin
Nitrogen and phosphorus contents in 44 wetland species from the Lake Erhai Basin
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作者：
L. Guihua
营养限制（主要是氮或磷）被认为是生态系统发展的驱动力。假设植被的氮磷比直接反映了养分限制的性质。在植被水平上，N:P比值14和16通常对应于N和P限制的生物量生产。因此，对植物氮、磷含量的研究可以大大增加我们对营养限制本质的有限认识，并为生态恢复提供指导。研究了洱海流域44种湿地植物的氮、磷含量。结果表明，该地区N、P的平均含量分别为15.7 mg/g和3.3 mg/g干重，N和P的平均含量分别为6.4 ~ 34.3 mg/g和1.4 ~ 6.5 mg/g，显著高于其他地区。N∶P比值在2.2 ~ 9.5之间，表明氮是洱海流域的限制因子。植物地上部和地下部氮、磷含量差异显著。地上部分的平均氮含量（16.7 mg/g）和磷含量（3.6 mg/g）显著高于地下部分（9.8 mg/g和3.1 mg/g）。各官能团间氮、磷含量差异显著。沉水种氮含量（17.7 mg/g）显著高于突水种（12.1 mg/g）和自由漂浮/浮叶种（13.4 mg/g），泥滩种磷含量（3.6 mg/g）显著高于沉水种（2.6mg/g）。总体而言，地上组织生物量占全株生物量的72%，地上组织生物量占全株生物量的82%，地上组织生物量占全株生物量的75%，说明采收地上组织能有效去除湿地生态系统中的氮磷。
Nutrient limitation(mostly nitrogen or phosphorus) is thought be a driving force in ecosystem development.It was hypothesized that the N:P ratio of the vegetation directly reflects the nature of nutrient limitation.At vegetation level,N:P ratios 14 and 16 often correspond to N-and P-limited biomass production.The study on nitrogen(N) and phosphorus(P) contents of plants thus may greatly increase our limited knowledge of the nature of nutrient limitation and also provide guidance for ecological restoration.This paper investigated N and P contents of 44 wetland plants from the Lake Erhai basin.The results showed that the mean contents of N and P were 15.7 mg/g and 3.3 mg/g dry weight,and ranged from 6.4 to 34.3 mg/g for N and 1.4 to 6.5 mg/g for P,respectively,and they were markedly higher than those from other regions.The N ∶ P ratio ranged from 2.2 to 9.5,indicating that N was the limiting factor in the Lake Erhai basin.There was a significant difference in N and P contents between above-and belowground parts in plants.The mean N content(16.7 mg/g) and P content(3.6 mg/g) of aboveground part were significantly higher than those(N content of 9.8 mg/g and P content of 3.1 mg/g) of belowground part.There was a significant difference in N and P contents among functional groups.Submerged species exhibited significantly higher N contents(17.7 mg/g) than the emergent species(12.1 mg/g) and free-floating/floating-leaved species(13.4 mg/g),while mud-flat species had significantly higher P contents(3.6 mg/g) than submerged species(2.6mg/g).Overall,the biomass,and N and P contents of above-ground tissue respectively accounted for 72%,82% and 75% of those in the whole plant,which suggested that harvesting of above-ground tissue could effectively remove N and P from wetland ecosystem.