栽培模式对黄土高原沙棘人工林地土壤微生物多样性的影响研究

Hippophae rhamnoides L., commonly known as sea-buckthorn, is an Eurasian nitrogen-fixing actinomycetes plant species and is widely planted in Loess Plateau in China for soil and water conservation, wind-break and sand-fixing purposes. As we known, the different microbial diversity, nutrient utilization, as well as enzyme activity in soil of sea-buckthorn plantations obviously changed with different planting patterns, which also changed with the different seasons. Based on the fact that sea-buckthorn plantations gradually declined to some extent in Loess Plateau, the four most common planting models of sea-buckthorn plantations are chosen as the experimental materials in this plan. The population structure and function of soil microbiology, soil nutrient, and enzyme activity of soil will be systematically measured during the three different seasons. The influencing factors of soil fertility and relationship between forest growth and micro-ecological environment in soil were expected to illustrate under the different planting models. To authors' knowledge, this is the first research on decline mechanism of sea-buckthorn plantations in terms of micro-ecological environment of soil in Loess Plateau. The aim of this research is to provide certain advices for health evaluation and sustainable forest management of sea-buckthorn plantations in above-mentioned region.

沙棘是黄土高原丘陵区生态建设的重要树种之一，在保持水土、防风固沙和固氮改土等方面具有重要的生态、经济和社会意义。沙棘人工林随栽培模式的不同其林地系统中土壤微生物多样性、养分利用以及各种酶活性差异较大，并随季节变化。本项目针对黄土高原沙棘人工林出现衰退的现象，以黄土高原常见的4种沙棘人工林栽培模式为研究对象，拟对其不同生长季节林地土壤微生物的种群结构和功能、土壤养分以及酶活性等的动态变化规律进行研究，探讨不同栽培模式下沙棘人工林地土壤肥力的影响机理以及林木生长与土壤微生态环境之间的关系，并首次从林地土壤微生态环境的角度探索沙棘人工林衰败的原因，旨在为黄土高原沙棘人工林的健康评价和可持续性经营提供参考。

沙棘是黄土高原丘陵区生态建设的重要树种之一，在保持水土、防风固沙和固氮改土等方面具有重要生态、经济和社会意义。不同栽培模式的沙棘人工林，其林地土壤微生物多样性、养分利用以及各种酶活性差异较大，并随季节变化。本项目以立地条件相似，林龄相同的4种栽培模式下的沙棘人工林地（沙棘×侧柏、沙棘×刺槐、沙棘×油松、沙棘纯林）为实验对象，测定了不同季节土壤微生物种群结构的动态变化规律、土壤中酶活性的变化，以及养分特性等。初步明确了4种栽培模式下沙棘人工林地土壤养分、微生物特性与土壤酶活性之间的相互关系。研究结果表明：（1）4种沙棘人工林地各种菌群生物量、酶活性及部分土壤理化特性（有机碳、全磷、全钾、速效氮、速效磷）均为夏季最高，其次为秋季和春季。（2）春、夏、秋3个季节中，3种混交林地的总脂肪酸含量、细菌生物量、革兰氏阳性菌生物量、pH值、全磷、全钾含量均显著高于纯林；（3）土壤总PLFA、革兰氏阳性菌生物量（G+PLFA）、革兰氏阴性菌生物量（G-PLFA）均与土壤pH、总有机碳、全氮、铵态氮、速效钾、脲酶、多酚氧化酶、过氧化物酶呈显著正相关关系。（4）沙棘与油松或侧柏混交为试验区域两种较好的栽培模式，能有效改善土壤肥力。本项目的实施有助于深入探讨不同栽培模式下沙棘人工林地土壤肥力的影响机理以及林木生长与土壤微生态环境之间的关系，并首次从林地土壤微生态环境的角度探索了沙棘人工林衰败的原因，研究结果可为黄土高原沙棘人工林的健康评价和可持续经营提供一定的参考。