混合生物结皮对土壤养分的影响与群落结构之关联——以黄土丘陵区的生物结皮为例

自然条件下生物结皮是藻、藓及地衣等结皮类型以不同比例组成的混合群落,显著影响土壤养分含量,目前混合生物结皮对土壤养分的影响与其群落结构的关系尚不清楚,限制了混合生物结皮土壤养分的评估。为此,研究通过测定单一组成的藻结皮、藓结皮以及80%藻+20%藓、60%藻+40%藓、40%藻+60%藓和20%藻+80%藓4个不同藻藓比例的混合生物结皮土壤有机碳、全氮、全磷、速效磷、铵态氮和硝态氮含量,研究了混合生物结皮土壤养分与其群落结构之间的关联。结果显示：(1)藓结皮层土壤有机碳、全氮、速效磷、铵态氮和硝态氮含量显著高于藻结皮,分别高出166.4%、77.2%、55.1%、56.2%和42.2%。(2)藻藓混合生物结皮土壤有机碳、全氮、速效磷和铵态氮含量与组成和盖度等结构特征有关,可以通过单一类型生物结皮土壤养分含量与盖度加权预测混合生物结皮土壤养分储量。(3)混合生物结皮土壤有机碳、全氮、速效磷和铵态氮储量实测值(x)与预测值(y)拟合的线性函数分别为y=0.97x、y=0.96x、y=1.18x和y=0.92x。(4)混合生物结皮对全磷和硝态氮含量的影响与群落结构无关。生物结皮对下层0—5 ...

Effects of mixed biocrusts on soil nutrients and their association with community structure: A case study from Hilly Loess Plateau region

Biological soil crusts (Biocrusts) are a mixed community which composed of cyanobacteria, moss and lichen in different proportions under natural condition. They significantly affect the soil nutrients. However, the relationship between the soil nutrients of mixed biocrusts and its community structure is unclear, which would hinder the assessment of soil nutrients of mixed biocrusts. Therefore, this study measured the soil organic carbon, total nitrogen, total phosphorus, available phosphorus, ammonium nitrogen and nitrate nitrogen contents of cyanobacteria, moss and mixed biocrusts with different proportions of cyanobacteria and moss, which were 80% Cyanobacteria + 20% Moss, 60% Cyanobacteria + 40% Moss, 40% Cyanobacteria + 60% Moss, and 20% Cyanobacteria + 80% Moss in the Hilly Loess Plateau region. The results showed that (1) the soil organic carbon, total nitrogen, available phosphorus, ammonium nitrogen and nitrate nitrogen contents of moss were significantly higher than those of cyanobacteria by 166.4%, 77.2%, 55.1%, 56.2% and 42.2%, respectively. (2) The contents of organic carbon, total nitrogen, available phosphorus and ammonium nitrogen in mixed biocrusts of cyanobacteria and moss were related to the composition and coverage. The nutrient storage of mixed biocrusts could be predicted by weighting the nutrient content and coverage of single type of biocrusts. (3) The linear functions fitted by the measured values (x) and predicted values (y) of soil organic carbon, total nitrogen, available phosphorus and ammonium nitrogen storage in the mixed biocrusts were y=0.97x, y=0.96x, y=1.18x and y=0.92x, respectively. (4) The effect of mixed biocrusts on soil total phosphorus and nitrate nitrogen contents was not significantly related to the community structure. The biocrusts had little effect on the soil nutrients in the soil layer 0-5 cm. This study reveals the relationship between soil nutrients of mixed biocrusts and community structure, which provides scientific basis for accurately evaluating the effect of mixed biocrusts on soil nutrients under natural conditions.