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本文在广泛调查分析的基础上,通过数理统计方法,确定在珠江三角洲范围内,影响林木生长的主要土壤因子是pH、全盐量和水位状况。用逐步回归方法选出了最优方程。落羽杉(Taxodium distichum)、池杉(Taxodium ascendens)、木麻黄(Casua-rina equisetifolia)和水松(Glyptostrobus pensilis)是珠江三角洲农田防护林的主要造林树种。土壤反应的最佳适生值,落羽杉和池杉为pH6.1,木麻黄和水松为pH7.0—8.0。这4种树种都有一定的抗盐能力,在全盐量高达0.38％的盐渍土上,仍生长正常。但落羽杉和池杉的生长速度与土壤全盐呈负相关。耐水湿树种落羽杉、池杉和水松分别在离水面50厘米和30厘米的种植点上表现最佳。珠江三角洲可划分为5个立地类型,即低丘淋溶型;平原淡水型;河网潮灌型;滨海反酸型;滨海砂土型。根据不同的立地类型,提出了适宜的农田防护林造林树种,为适地适树,提供依据。
Based on extensive investigation and analysis, this paper determined that the main soil factors influencing the forest growth in the Pearl River Delta are pH, total salt and water status through mathematical statistics. Stepwise regression method was used to select the optimal equation. Taxodium distichum, Taxodium ascendens, Casua-rina equisetifolia and Glyptostrobus pensilis are the main afforestation species in farmland shelterbelts in the Pearl River Delta. The optimal soil fitness value of the response, Taxodium and Ipomoea syringae pH6.1, Casuarina and cork pH7.0-8.0. All four species have some ability of salt-resistance, and still grow normally on salinity soil with 0.38% of total salt content. However, the growth rate of Taxodium distichum and Taxanus was negatively correlated with total salt in soil. Water-resistant wet tree Taxodium, Ipomoea cinnabar and cork were the best performing at planting points 50 cm and 30 cm above the water surface. The Pearl River Delta can be divided into five site types, namely, lowland leaching type; plain freshwater type; tidal channel irrigation; coastal acid; coastal sand soil type. According to different site types, put forward suitable afforestation tree species of farmland shelterbelt, to provide suitable basis for suitable tree.