长周期母竹留养模式的毛竹林土壤养分状况评价

Evaluation of Soil Nutrient Status in Different Management Duration under Long-period Bamboo Retention Pattern

2017年,在福建省漳平市新桥镇高美村选择试验地,以毛竹(Phyllostachys edulis)林为研究对象(竹林密度1600~1800株·hm^(-2)),以空间替代时间,选取长周期母竹留养模式(留养母竹的竹龄为1~3年生,每种竹龄母竹数量各占33%)连续经营的毛竹笋用林——5种连续经营(经营时长)4、5、6、7、8 a的毛竹林,以传统经营模式为对照,设置样地10 m×10 m,每个类型样地3个重复,共18块样地;在标准地内按照S形5点采样法,按照土层深度(h)0<h≤10 cm、10 cm<h≤20 cm、20 cm<h≤40 cm、40 cm<h≤60 cm分别采集土壤样品;按照《森林土壤分析法》测定土壤养分,进行土壤养分丰缺划分;以土壤全氮质量分数、碱解氮质量分数、全磷质量分数、速效磷质量分数、全钾质量分数、速效钾质量分数、有机质质量分数7项指标作为评价土壤养分情况的土壤因子,对7个土壤因子进行标准化处理后,采用主成分分析法、加权求和法、聚类分析法,分析不同经营时长时长周期母竹留养模式毛竹林的土壤养分状况。结果表明:研究区毛竹林土壤总体养分质量分数较低,全氮质量分数、碱解氮质量分数丰富,磷、钾元素缺乏。影响长周期母竹留养土壤养分的主要因素,为全氮质量分数、碱解氮质量分数、全磷质量分数、速效磷质量分数、有机质质量分数。土壤养分综合评价指标值的聚类分析表明,养分综合得分可分为极高、高、中等、低、极低5个养分水平,样本数所占比例分别为2.78%、13.89%、23.61%、40.28%、19.44%,不同经营时长长周期母竹留养模式的毛竹林土壤养分,由优到劣依次为连续经营7 a、连续经营6 a、传统经营模式(对照)、连续经营5 a、连续经营4 a、连续经营8 a,表明长周期母竹留养最佳经营期限为7 a,长周期母竹留养模式连续经营8 a时土壤养分出现衰退现象,需要及时补充缺乏养分,维持毛竹林生产力。

In 2017,the experimental site was selected in Gaomei Village,Xinqiao Town,Zhangping City,Fujian Province,using Phyllostachys edulis forest(bamboo forest density 1600-1800 ind.hm 2).By using space instead of time,and selecting long-period mother bamboo to stay,the cultivation mode(the age of reserved mother bamboos is 1 to 3 years old,and the number of mother bamboos of each age accounts for 33%)of continuously managed moso bamboo shoot forest-5 types of continuous management(operation duration)4,5,6,7,for an 8-year-old moso bamboo forest,using the traditional management model as a control,a sample plot of 10 m×10 m was set up,with 3 replicates of each type of plot,a total of 18 plots.In the standard plot,according to the S-shaped 5-point sampling method,according to the soil depth(h),soil samples were set at 0<h≤10 cm,10 cm<h≤20 cm,20 cm<h≤40 cm,and 40 cm<h≤60 cm.In order to measure soil nutrients,the‘Forest Soil Analysis Method’is employed to classify soil nutrient abundance and deficiency.The analysis method is with seven indicators:total nitrogen content,alkaline hydrolyzable nitrogen content,total phosphorus content,available phosphorus content,total potassium content,available potassium content,and organic matter content.These indicators are used as soil factors to evaluate soil nutrients.The soil nutrient status of moso bamboo forests with different management durations and long-cycle mother bamboo retention modes were analyzed.After standardizing the factors,the principal component analysis method,weighted summation method,and cluster analysis method were employed.The results showed that the overall nutrient content of the moso bamboo forest soil in the study area was low,the content of total nitrogen and alkaline hydrolyzable nitrogen were abundant,and the elements phosphorus and potassium were deficient.The main factors influencing soil nutrients in long-term mother bamboo cultivation include the contents of total nitrogen,alkali-hydrolyzable nitrogen,total phosphorus,available phosphorus,and organic matter.Cluster analysis of soil nutrient comprehensive evaluation index values shows that the comprehensive nutrient score can be divided into five nutrient levels:extremely high,high,medium,low,and very low.The proportions of the number of samples are 2.78%,13.89%,23.61%,23.61%,40.28%,and 19.44%,respectively.The soil nutrients of moso bamboo forests with different management periods and long-term mother bamboo retention modes,from best to worst,are continuous operation 7 a,continuous operation 6 a,traditional operation mode(control),continuous operation 5 a,continuous operation 4 a,and continuous operation 8 a,indicating that the optimal operation period of Long-period Bamboo Retention Pattern is 7 years.When the Long-period Bamboo Retention Pattern is continuously operated for 8 a,soil nutrients will decline,and the soil needs to be replenished in time to maintain the productivity of the moso bamboo forest.