上海城市绿地典型毛竹群落土壤特征研究

The Soil Characteristics of Phyllostachys heterocycla cv. Pubescens Communities in the Urban Green Land in Shanghai

毛竹是亚热带城市景观竹林的主要竹种之一,但土壤性状制约了城市毛竹林的可持续生长发育。以上海市延中绿地、上海植物园、新江湾城绿地的毛竹林为研究对象,对不同栽植模式、管护强度下的毛竹景观林生长状况进行监测,比较分析毛竹林土壤理化性质和微生物特征,探讨毛竹生长与土壤性状的关系。结果表明:(1)毛竹群落0~20 cm、20~40 cm土壤的毛管孔隙、总孔隙度、土壤通气度均显著低于同层次的对照裸地,而非毛管孔隙则相反,土壤容重则差异不大;毛竹群落0~20 cm、20~40 cm土壤的最小持水量、最大持水量、毛管持水量均显著低于裸地。可见,毛竹林可能影响绿地土壤孔隙状况。(2)在20~40 cm土层,除有机质含量外,裸地土壤的全氮和水解性氮均显著低于毛竹群落;而在40~60 cm土层,三者含量均低于毛竹群落,且腐殖质含量变化规律与有机质一致,但腐殖质不同组分变化趋势差异较大,仅富啡酸含量均显著高于裸地。因此,毛竹生长期养分高消耗导致主要鞭根层土壤有机质含量显著降低,土壤肥力衰退。同时,精细管护的延中绿地毛竹群落土壤微生物总数最高,表明养护管理对土壤微生物数量产生影响。(3)上海城市毛竹年际高度和胸径生长量远低于适生区,后期管护虽显著提高毛竹粗度、高度和出笋量,但由于总体养分含量和有效性差异,毛竹高生长和径生长策略有差异。(4)主因子分析结果表明,影响上海城市毛竹生长的主要土壤特征因子为土壤养分含量(以土壤全氮含量、有机质含量等表征)、土壤总孔隙度和土壤微生物,主因子的累积贡献率达到76.19%。因此,非适宜生长区的城市毛竹林管护应突出土壤养分与土壤结构改良相结合。

Phyllostachys heterocycla cv. Pubescens is one of the main ornamental bamboos in subtropical cities,in which the normal growth and sustainable management is limited by soil properties. In the Phyllostachys heterocycla communities( bamboo communities) respectively located in Shanghai Square Park,Shanghai Botanical Garden and New Jiangwan City Greenland,the bamboo growth status was monitored under various planting modes and maintenance intensities,and the microorganism features,physical and chemical properties of the soil were analyzed. The aim is to explore the relationship between the bamboo growth and soil properties. The results showed that( 1) the soil capillary porosity,total porosity and soil aeration at the depth of 0- 20 cm and 20- 40 cm in the bamboo communities were all significantly lower than that of the barren land,but the non-capillary porosity was significantly higher than that of the barren land. However,the soil bulk density of the bamboo communities and the barren land were similar to each other. The minimum water holding capacity,maximum water holding capacity and capillary water holding capacity of the soil at the depth of 0- 20 cm and 20- 40 cm in the bamboo communities were all significantly lower than that of the barren land. Thus,the bamboo may affect the soil porosity of urban green land.( 2) Except for the soil organic matter,the contents of total nitrogen and hydrolysable nitrogen of soil at the depth of 20- 40 cm and 40- 60 cm in the barren land were significantly lower than that in the bamboo communities. The soil humus content showed the same variation trend as the soil organic matter. Yet,the contents of different components of the soil humus varied differently,and only the soil Fulvic acid of the bamboo communities was significantly higher than that of the barren land. The high nutrition consumption of the bamboo significantly decreased the soil organic matter,reducing the soil fertility. Meanwhile,the soil microorganism amount of the bamboo communities with good maintenance in Shanghai Square Park was the highest,indicating that the maintenance intensity may affect the soil microorganism amount of bamboo communities.( 3) Because of the limit of soil conditions,the annul increments in height and diameter of Ph. heterocycla cv. Pubescens in shanghai were far less than that of the bamboos in suitable distribution area,although well maintenance may increase the height,diameter and natality of the bamboo shoots,the bamboo may change the growth strategy to balance with height and diameter growth,according to the availability of soil nutrients.( 4) the principle factors affecting the bamboo growth included the soil nutrients( such as total nitrogen,organic matter and so on),the total porosity and the amount of soil microorganism,amounting to a Cumulative variance contribution rate of 76. 19%. Therefore,in the urban green land,these factors should be emphasized during the planting and maintaining of Ph. heterocycla cv.Pubescens,and soil improvement materials should be added to enhance the microbial activities and porosity of the soil.