不同喀斯特土壤类型下常见蕨类植物氮磷养分策略差异及其与土壤养分供给关系

Efficiency of Nitrogen and Phosphorus Nutrients of Common Ferns and the Ralationship with Soil Supply in Different Karst Soil Types

关键词:  喀斯特地区  不同土壤类型  蕨类植物  氮磷养分特征  养分适应策略

Key words:  karst areas  different soil types  the common ferns  N and P nutrient characteristics  nutrient adaptation strategies

摘要:

蕨类植物是喀斯特生态系统的先锋植物,研究其对瘠薄的喀斯特土壤的适应策略,对退化生态系统的恢复与重建具有重要意义。本文以喀斯特地带性黄壤和非地带性石灰土上均有分布的常见蕨类植物为试材,研究了两种土壤类型上其根系有机酸分泌特征、氮磷素吸收与分配特征、地上部分氮磷质量比(w(N) ∶ w(P))等养分指标的差异,及该差异的形成与土壤氮磷养分供给的关系。结果表明:①石灰土上蕨类植物根系分泌的有机酸主要为酒石酸、草酸和苹果酸,黄壤上为苹果酸、酒石酸和柠檬酸,且石灰土上根系分泌的有机酸总量远高于黄壤；②与黄壤上生长的蕨类植物相比,石灰土上蕨类植物干物质积累量、磷素与氮素吸收量均较高,分别高出73.1%、30.5%和23.5%；③两种土壤条件下蕨类植物地上部分氮、磷素平均含量均较地下部分高；石灰土上蕨类植物地上部分w(N) ∶ w(P)为 13.20,黄壤上为11.35；④两种土壤条件下蕨类植物的氮素吸收量均与土壤有效磷含量呈显著性正相关,说明蕨类植物对土壤氮素的吸收利用受土壤有效磷含量的限制。综上可知,蕨类植物在两种土壤类型上的氮磷养分利用与分配策略存在显著差异,其在石灰土上生长时对土壤养分循环及利用的影响较黄壤上大。

Abstract:

To explore the adaptation strategies of plants in karst areas to soil nitrogen and phosphorus nutrients, this paper took the common ferns in karst areas as the research object, and studied the secretory characteristics of organic acid, absorption and distribution characteristics of N and P nutrients, N and P ratio of the above-ground portion of ferns under karst zonal soil (acid soil) and non-zonal soil (lime soil) condition. The results showed that: ①The kinds of organic acid secreted by fern under lime soil condition were mainly tartaric acid, oxalic acid and malic acid, while those under acid soil condition were malic acid, tartaric acid and citric acid, and the total amount of organic acids secreted by fern under lime soil condition was more than that under acid soil condition; ②Compared with the ferns distributed under acid soils condition, the average values of dry matter accumulation, P and N untake of ferns under lime soil dondition were higher, which were 73.1%, 30.5% and 23.5%; ③The average N and P content of the above-ground part of ferns were higher than that of the under-ground part under the acid and lime soil conditions. The w(N) to w(P) ratio of the above-ground part of ferns under lime soil condition was 13.20 and 11.35 under acid soil condition; ④Under the acid and lime soil conditions, N uptake was positively correlated with soil available P content. This results indicated that the uptake and utilization of soil nitrogen of ferns was limited by the content of soil available P. There were significant differences in N and P utilization and distribution strategies between the two soil types, when ferns growing under the lime soil condition，they had greater influences on soil nutrient cycling and utilization than those under the acid soil condition.