小兴安岭阔叶次生林内红松与常见阔叶树种地下资源生态位研究

Niche of underground resources of Pinus koraiensis and common broadleaved tree species in broadleaved secondary forest of Xiaoxing’anling Mountains of northeastern China

【目的】探究小兴安岭地区阔叶次生林内红松与常见阔叶树种的地下资源生态位分离与重叠,以期为恢复次生林合理选择树种及东北次生林的科学经营提供一些参考依据。【方法】对次生林内红松与白桦、山杨、蒙古栎、水曲柳和紫椴等阔叶树种的地下营养空间生态位、吸收土壤水分的季节生态位和数量生态位、吸收土壤养分的季节生态位和数量生态位以及吸收养分形态生态位等方面进行了研究。【结果】红松与阔叶树种在地下营养空间生态位、吸收土壤水分的季节生态位、吸收土壤养分的季节生态位和数量生态位、吸收土壤养分形态生态位等均存在分离。具体表现为:(1)阔叶树种吸收根主要集中分布于土壤表层(0~20 cm),为“浅根性”特征;而红松则相反,其吸收根分布比率在表土较低,在下层土壤空间(30~60 cm)明显较高,相对为“深根性”趋势。(2)阔叶树种吸收土壤水分一般从5月中开始至9月下旬结束;而红松从4月初开始至10月下旬仍有蒸腾。(3)阔叶树种吸收氮养分大约在5月上旬至9月下旬,吸收期较短,夏季养分吸收高峰较陡且峰期明显;而受阔叶树种庇荫的红松在4-10月的整个生长季中一直较平缓地吸收氮养分,夏季养分吸收高峰较缓且峰期不明显。(4)阔叶树种对N养分的消耗量较大且利用效率较低,属于高耗低效型;而红松对N养分的消耗量则相对较小,利用效率较阔叶树种高10.7%~36.8%,属于低耗高效型。(5)在对N养分化学形态的偏向选择性方面,红松叶硝酸还原酶活性较低;而阔叶树种的叶硝酸还原酶活性最高,其中,白桦、山杨和蒙古栎约是红松的6.0~6.5倍,水曲柳和紫椴约是红松的2.6倍和2.7倍。(6)红松与白桦、山杨、蒙古栎、水曲柳的地下资源生态位重叠较小,分别为0.502、0.426、0.628、0.374,而紫椴与红松的地下资源生态位重叠高达0.903。【结论】从地下资源生态位看,红松与白桦、山杨、蒙古栎、水曲柳、紫椴均为优化混交组合,且红松与阔叶树种的地下资源生态位分离对其长期共存和混交群落持续稳定高产都有重要意义。

[Objective] The niche separation and overlap of underground resources between Pinus koraiensis and common broadleaved tree species in broadleaved secondary forests in Xiaoxing’anling Mountains of northeastern China were explored, in order to provide some reference for the rational selection of tree species in secondary forests and the scientific management of secondary forests in northeastern China. [Method] The spatial niche of underground nutrition, seasonal niche and quantitative niche of soil moisture absorption, seasonal niche and quantitative niche of soil nutrient absorption and morphological niche of nutrients absorption of Pinus koraiensis and broadleaved tree species such as Betula platyphylla,Populus davidiana, Quercus mongolica, Fraxinus mandshurica and Tilia amurensis in secondary forest were studied. [Result] There were separations between Pinus koraiensis and broadleaved tree species in the niche of underground nutrition space, seasonal niche for absorbing soil water, seasonal niche and quantitative niche for absorbing soil nutrients, and niche for absorbing soil nutrient forms. The concrete manifestations were as follows:(1) The absorption roots of broadleaved tree species were mainly distributed in the soil surface layer(0-20 cm), which was characterized by “shallow roots”. On the contrary, the distribution ratio of absorbing roots of Pinus koraiensis was lower in the topsoil and higher in the lower soil space(30-60 cm), which was relatively “deep-rooted”.(2) The broadleaved tree species generally began to absorb soil moisture from the middle of May to the end of September in a year;however, Pinus koraiensis still had transpiration from early April to October in a year.(3) The broadleaved tree species absorbed nitrogen from May to September in a year, with a short absorption period, and the peak of nutrient absorption in summer was steep and obvious;however, Pinus koraiensis, which was shaded by broadleaved tree species, had been slowly absorbing nitrogen nutrients in the whole growing season from April to October in a year, and the peak of nutrient absorption in summer was slow and the peak period was not obvious.(4) The broadleaved tree species had a large consumption of N nutrient and a low utilization efficiency, which belonged to high consumption and low efficiency;however, the N nutrient consumption of Pinus koraiensis was relatively small, and its utilization efficiency was 10.7%-36.8% higher than that of broadleaved tree species, which belonged to low consumption and high efficiency.(5) The nitrate reductase activity of Pinus koraiensis leaves was low in the selectivity of N nutrient chemical forms. The nitrate reductase activity in the leaves of broadleaved tree species was the highest, among which Betula platyphylla, Populus davidiana and Quercus mongolica were about 6.0-6.5 times as high as that of Pinus koraiensis and Fraxinus mandshurica and Tilia amurensis were about 2.6 and 2.7 times as high as that of Pinus koraiensis.(6) The niches overlap between Pinus koraiensis and Betula platyphylla, Populus davidiana, Quercus mongolica, Fraxinus mandshurica were small, which were 0.502, 0.426, 0.628 and 0.374 respectively, while the niche overlap between Tilia amurensis and Pinus koraiensis was as high as 0.903. [Conclusion] According to the niche of underground resources, Pinus koraiensis and Betula platyphylla, Populus davidiana, Quercus mongolica, Fraxinus mandshurica and Tilia amurensis are all optimized mixed combinations, and the separation of niche of underground resources between Pinus koraiensis and broadleaved tree species are of great significance to their long-term coexistence and the sustained, stable and high yield of mixed communities.