塔里木河中游胡杨(Populus euphraticu)“肥岛”的养分特征研究

Nutrient Characters of Fertile Islands of Populus euphraticu in the Middle Reaches of Tarim River

利用传统统计学和地统计学方法，对塔里木河中游胡杨“肥岛”的养分特征进行了研究。结果表明：胡杨周围的土壤养分向冠幅内聚集，具有较强的富积强度，形成了明显的“肥岛”特征。大胡杨冠幅下4种养分（有机质、碱解氮、有效磷、速效钾）分别比冠幅外高64．94％，72．87％，61．70％和185．20％；中胡杨为5．36％，5．39％，47．02％和93．43％；小胡杨为27．96％，10．20％，67．48％和218．59％；但不同发育阶段土壤养分的富积率具有一定的差异，有机质表现为极显著，碱解氮和速效钾表现为显著，而有效磷没有显著差异。单株胡杨土壤养分变异系数属中等强度，半方差函数模型除碱解氮为高斯模型外，其他为球状模型，块金值／基台值[Co／（C＋Co）]的比值均在25％附近，表明空间相关性强烈，整体看来土壤养分的变异性主要由结构性因素引起的。胡杨养分的“肥岛”作用范围（7．5～11．1m）大于冠幅半径（5m）；通过克里格插值图分析，胡杨立地土壤养分表现出不同程度的“肥岛”效应。

The nutrient characters of River were studied in this paper using fertile islands of Populus euphraticu classical statistics and geostatistics the surrounding soil nutrients of Populus euphraticu were collected in coro in the middle reaches of Tarim principle. Results showed that nal breadth center., the contents of four kinds of nutritions（organic matter, available nitrogen,available phosphorous and available potassium） were respeetively 64.94%,2.87%,61.70% and 185.20% higher than the contents of the external partof coronal breadth which is under the coronal breadth of the big Populus euphraticu . The figures of the middle Populus euphraticu were 5.36% ,5.39% ,47.02% and 93.43% ,and that of the small Populus euphraticu were 27.96%, 10. 20%, 67. 48% and 218.59%. And all of these formed evident fertile islands characters. There were different enrichment ratios among the soil nutrient at different growth phases, the enrichment ratios of organic matter showed great difference; the enrichment ratios of available nitrogen and available potassium showed outstanding difference; the enrichment ratios of available phosphorous showed no outstanding difference. The variation coefficient of individual Populus euphraticu had the middle intensity. All of the semivariogram functions were spherical model excepting that available nitrogen was gaussian model. All of the ratios of Co/（C＋ C0） were about 25 %, which showed that there were sharp special relativity and the variability were brought from structural factors. The effective ranges（7.5-11.1m） of nutrientsfertile islands of Populus euphraticu were greater than coronal breadth radius（Sm）. By analyzing Kriging interpolation map, the soil nutrients of Populus euphraticu showed fertile islands can produce different effect.