西南干旱河谷植物群落组分生物量的纬度格局及其影响因素

Latitudinal patterns and underlying factors of component biomass in plant communities in the arid valley of southwest China

研究植物群落不同组分生物量的纬度格局及其与生物、非生物因子的定量关系有助于揭示植物对环境的适应性,能够解释生态系统结构和功能的空间差异性及其成因。该研究在西南干旱河谷跨越9个纬度(23.23°–32.26°N),布置101个群落样方(4 m×6 m)。采用收割法测定群落及组分生物量,分析生物量在纬度梯度上的变化规律及其影响因子。结果显示,干旱河谷群落平均生物量为(17.05±1.09)t·hm^(2),其中,灌木平均生物量为(11.51±1.03)t·hm^(2),占60.2%;草本平均生物量为(2.11±0.21) t·hm^(2),占15.6%;凋落物平均生物量为(3.41±0.34) t·hm^(2),占24.1%。群落生物量和灌木生物量随纬度升高而显著增加,草本生物量随纬度升高无明显变化,凋落物生物量随纬度的升高而显著降低。随着纬度增加,灌木生物量的比例明显增大,草本生物量的比例无明显变化,凋落物生物量的比例明显降低。灌木优势度及丰富度的变化是驱动干旱河谷植被生物量在纬度梯度上变化的主要内在因子,而外在因子中,气候因子对群落及组分生物量的影响显著高于土壤因子。

Aims The study of the pattern of biomass variations and their drivers along environmental gradients commonly contributes to the understanding of plant’s adaptability to environmental changes, further explains the spatial differences in vegetation and ecosystem processes. We investigated the biomass latitudinal patterns of plant communities and its components and revealed the quantitative relationships of biomass with climatic, soil and community structure as well as species diversity.Methods In order to analyze the variation patterns of biomass along the latitude gradient and the drivers, we set up a total of 101 plots(4 m × 6 m) across nine region along latitude in the arid valley of southwest China(23.23°–32.26° N), to investigate biomass and species composition of plant communities and its components.Important findings In the arid valley, the average biomass of community was(17.05 ± 1.09) t·hm^(2), of which the average biomass of shrub, herb and litter were(11.51 ± 1.03),(2.11 ± 0.21) and(3.41 ± 0.34) t·hm^(2), respectively, with each of them accounting for 60.2%, 15.6%, and 24.1% of the community biomass. With the increase of latitude, community biomass increased significantly. Shrub biomass and their proportion also increased significantly, herb biomass and their proportion remained consistent, whereas litter biomass decreased significantly. The changes of shrub dominance and abundance were the main internal factor for vegetation biomass variation along the latitude gradient. Additionally, compared with soil factors, climatic factors had a more significant impact on the biomass changes of communities and its components.