科尔沁沙地小叶锦鸡儿地上-地下生物量分配格局

Allocation patterns of above-and below-ground biomass of Caragana microphylla in Horqin Sandy Land,North China

以科尔沁沙地18年生(成龄)和4年生(幼龄)人工小叶锦鸡儿以及天然小叶锦鸡儿灌丛为研究对象,采用分层挖取根系法调查不同植被区小叶锦鸡儿的根系分布特点,研究其在生物量分配、根冠比、根系分布等方面对干旱环境的响应。结果表明:1)小叶锦鸡儿倾向于把更多的生物量分配于地下,其中天然植被地下生物量比重最大,4年生植被地下生物量比重最小。2)小叶锦鸡儿灌丛根系生物量随着土层深度的增加而逐渐减少,其根系主要分布在0～100cm土层中。3)4年生小叶锦鸡儿吸收根呈现浅层分布特性,在地下0～50cm吸收根生物量显著高于18年生和天然植被(P<0.05);18年生和天然植被吸收根更多分布于50～100cm土层中。天然小叶锦鸡儿输导根生物量在50～100cm土层中显著高于4年生和18年生植被(P<0.05)。4)小叶锦鸡儿灌丛地上-地下生物量符合异速生长模型的幂函数。

Taking the 4 and 18-year-old artificial plantations and the natural stand of Caragana microphylla in Horqin Sandy Land as the objects, and through digging root system by layers, this paper investigated the features of C. microphylla root distribution in different vegetation zones, and studied the responses of C. microphylla in its biomass allocation, root/shoot ratio, and root distribution to dry environment. The C. microphylla tended to allocate more biomass to roots. Among the three vegetation zones, natural stand and 4 years old artificial plantation had the largest and the smallest proportion of belowground biomass, respectively. The root biomass decreased gradually with soil depth, and the roots were mainly distributed in the 0-100 cm soil layer. The biomass of the absorptive roots of 4 years old C. microphylla plantation was more distributed in surface soil layer, being significantly greater than that of 18 years old plantation and natural stand （P〈0.05） in 0-50 cm soil layer. However, the 18 years old plantation and the natural stand had more absorptive root biomass in 50-100 cm soil layer. The conductive root biomass of natural stand in 50-100 cm soil layer was significantly greater than that of 4 and 18-year-old plantations. The relationships between the above and belowground biomass allocations of C. microphylla were characterized by allometry model.