庐山植物园11种植物的根际土壤氮磷有效性和酶活性

通过比较不同种源植物的土壤理化性质与生物学活性的差异及根际效应,探讨不同种源植物对庐山酸性山地土壤的环境适应性。在庐山植物园内选择引种多年的11种不同种源的常绿树种,在生长季节中采集根际土和非根际土,测定有机碳含量、碱解氮及有效磷含量、脲酶和酸性磷酸酶活性,并分析各树种根际土壤氮磷养分及酶活性的根际效应。结果表明,（1）不同树种之间的根际土壤酸性磷酸酶（P〈0.01）、有效磷（P〈0.05）和碱解氮（P〈0.01）存在明显差异,而脲酶没有差异。（2）根际与非根际土壤氮磷有效性和酶活性表现出不同的特征,大部分树种根际土壤有效磷及酸性磷酸酶存在一定的根际效应（R/S〉1）,例如红花木莲Manglietia insignis、桂南木莲Manglietia chingii及云南拟单性木兰Parakmeria yunnanensis的根际与非根际土壤有效磷含量存在显著差异（P〈0.05）,红花木莲、桂南木莲、巴东木莲Manglietia patungensis、红茴香Illicium henryi及红皮糙果茶Camellia crapnelliana与乡土树种云锦杜鹃Rhododendron fortunei根际与非根际土壤酸性磷酸酶存在显著差异（P〈0.05）。但是,根际与非根际土壤碱解氮和脲酶差异不明显,有的甚至出现脲酶的根际负效应（R/S〈1）,如巴东木莲和红花木莲等树种根际土壤低于非根际土壤（P〈0.05）。（3）不同种源树种影响下的土壤有效磷和酸性磷酸酶的根际效应（R/S比值）明显,原产西南地区的树种如桂南木莲、云南拟单性木兰和巴东木莲与华南地区的红花木莲、红茴香等土壤有效磷的根际效应（R/S〉1.5）比原产华东亚热带地区的深山含笑Michelia maudiae和云锦杜鹃更明显,相应的酸性磷酸酶的根际效应也较高。土壤脲酶和碱解氮的根际效应却不明显。（4）土壤有机碳与碱解氮、有效磷和酸性磷酸酶存在显著正相关关系（P〈0.01）,土壤碱解氮与有效磷（P〈0.01）和酸性磷酸酶（P〈0.05）具显著正相关关系,酸性磷酸酶与pH值（P〈0.05）显著负相关,说明根际土壤有机物质的积累对根际微区的理化环境及根际土壤养分活性具有重要影响。

Available nitrogen and phosphorus and biological enzyme activities in rhizosphere soils beneath 11 plant species in Lushan Mountain

To assess the environmental adaptability of tree species from different provenances to the acid soils in Lushan mountains, the physicochemical characteristics and biological enzyme activities in the soils beneath different trees and their rhizospheric effects were investigated. 11 tree species introduced from different provenances were selected typically in Lushan botanical garden. In growing seasons, the rhizosphere and non-rhizosphere soils were collected, and the soil pH values, organic carbon contents, available nitrogen and available phosphorus contents, urease and acid phosphatase activities were measured. The results showed that： （1） there were significant differences in the available nitrogen contents （P〈0.01）, phosphorus contents （P〈0.05） and the acid phosphatase activities （P〈0.01） except for the urease activities in soils beneath different tree species. （2） There presented different characteristics in the nutrient availability and enzyme activities in between rhizosphere and non-rhizosphere soils beneath different tree species. There were significant differences （R/S〉I） in the available phosphorus contents and the acid phosphatase activities in between rhizosphere and non-rhizosphere soils beneath most tree species such as Manglietia insignis, Manglietia chingii. The available phosphorus contents were significant differences （P〈0.05） in between rhizosphere and non-rhizosphere soils beneath Parakmeria yunnanensis. There were significant differences （P〈0.05） in the acid phosphatase activities in between rhizosphere and non-rhizosphere soils beneath some tree species such as Manglietia insignis, Manglietia chingii, Manglietia patungensis, lllicium henryi, Camellia crapnelliana and native tree （Rhododendron fortunei）. However, there were little differences in the available nitrogen and urease activities in between rhizosphere and non-rhizosphere soils among all tree species. The urease activities in non-rhizosphere soils were higher than in rhizosphere soils beneath some trees such as Manglietia insignis and Manglietia patungensis. （3） There were significant differences in the available phosphorus contents and the acid phosphatase activities in between rhizosphere and non-rhizosphere soils beneath most tree species from different provenances. For example, the differences were larger beneath the trees from southwestern region in China such as Manglietia chingii, Manglietiapatungensis and Parakmeria yunnanensis and trees from south of china such as Manglietia insignis and Illicium henryi than that beneath trees such as Michelia maudiae and Rhododendronfortunei form east of china. The same were that in the acid phosphatase activities. However, there wcrc little differences in the urease activities and available nitrogen contents in between rhizosphere and non-rhizosphere soils beneath all tree species. （4） The available nitrogen, available phosphorus contents and acid phosphatase activities were significantly and positively related to the organic carbon contents （P〈0.01） in rhizosphere soils. Both the available phosphorus contents （P〈0.01） and the acid phosphatase activities （P〈0.05） were significantly and positively related to the available nitrogen, and the acid phosphatase activities was significantly and negatively correlated with the pH values （P〈0.05）. This indicated that the pool of soil nutrient and the physicochemical environments in the rhizospheric area were influenced by the accumulation of the soil organic matters.