Patterns of CO2 exchange in biological soil crusts of successional age
Patterns of CO2 exchange in biological soil crusts of successional age
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DOI：
10.1016/s0038-0717(00)00004-3
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发表时间：
2000-07
影响因子：
9.7
通讯作者：
E. Zaady;U. Kuhn;B. Wilske;L. Sandoval-Soto;J. Kesselmeier
中科院分区：
文献类型：
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作者：
E. Zaady;U. Kuhn;B. Wilske;L. Sandoval-Soto;J. Kesselmeier
本文的目的是确定CO2交换率是否可以作为确定不同演替阶段生物土壤结皮的发育状态和种类或功能组成的指标。我们量化了来自内盖夫沙漠两个不同地点不同微生境的样品的二氧化碳交换率，即二氧化碳同化和呼吸。在结皮群落的演替过程中，最早在土壤表面定居的是蓝藻，其次是绿藻、苔藓和地衣。物理影响，如土壤结构和类型，辐射强度，以及地形特征，如坡向，影响水的有效性和土壤水分，影响演替路径和土壤结皮群落。在物质条件相同的情况下，干扰是特定演替阶段的关键因素。我们发现在Nizzana站点，呼吸和光合作用的CO2交换都有很大的梯度。尼扎纳沙丘的样品表现出明显的活动梯度，沙丘底部的同化速率(约70μmolCO2m−2min−1)和呼吸速率(60-70μmolCO2m−2min−1)都很高，向顶部递减。内盖夫沙漠的土壤结皮样本显示出类似的数值。因此，由于含有这种具有主要光合作用活性生物的生物土壤结皮的生态型在沙漠、北方和北极系统中是一种普遍现象，它们对痕量气体和元素的全球循环的贡献可能对全球预算具有重大意义。
The objective of this paper was to determine whether CO2exchange rates could be used as an indicator for determining the state of development and species or functional composition of biological soil crusts in different successional stages. We quantified the CO2exchange rates, i.e., CO2assimilation and respiration, in samples from different microhabitats at two different sites in the Negev desert. In the successional pathway of the crust communities, the pioneers in colonising the soil surface are the cyanobacteria; green algae, mosses and lichens then follow. Physical influences such as soil structure and types, radiation intensity, and topographic traits such as slope directions that affect water availability and soil moisture, influence the successional pathways and the soil crust community. When physical conditions are the same, disturbances are key factors for a specific successional stage. We found a substantial gradient of CO2exchange at the Nizzana site for both respiration and photosynthesis. Samples from the sand dunes at the Nizzana site showed a pronounced activity gradient with high rates for assimilation (around 70 μmol CO2m−2min−1) as well as respiration (60–70 μmol CO2m−2min−1) at the base of dunes, decreasing towards the top. The soil crust samples of the Negev desert show comparable values. Hence, as ecotypes containing such biological soil crusts with dominant photosynthetically active organisms are a widespread phenomenon in desert, boreal and arctic systems, their contribution to the global cycling of trace gases and elements can be significant for global budgets.