生物结皮在干旱、半干旱地区广泛发育。迄今,有关生物结皮发育过程中土壤物理属性的响应仍不明确。论文采用野外调查与室内分析相结合的方法,定量研究不同生物量生物结皮对土壤物理属性的影响。结果表明:①生物结皮的发育能够细化土壤,当生物结皮由初期藻结皮演替至60%~80%苔藓结皮时(5等级),生物结皮层粗砂粒含量降低了86%;②随着生物结皮生物量的增加,生物结皮层土壤容重和硬度较初期分别降低了15%和68%,田间持水量和孔隙度分别增加了36%和14%;生物结皮层粘结力是下层土壤的6~7倍;③生物结皮的发育对土壤物理属性的影响与生物量有关,当苔藓生物量达2.91±0.12 g/dm2时,其土壤物理属性基本稳定。研究结果为揭示生物结皮抗侵蚀机理提供了科学参考。
Biological soil crusts (biocrusts) are ubiquitous living surface covers in many arid and semi-arid regions. It has been demonstrated that the coverage of biocrusts was over 70% in the hilly Loess Plateau region of China and it played many important roles, such as exerting observably impact on soil properties and improving soil antierodibility. But the response of soil physical properties to the development of biocrusts has been unclear so far. The objective of the study was to determine the impact of development of biocrusts (i.e. with variable biomass) on soil physical properties in hilly Loess Plateau region. In this study, soil samples were collected after biocrusts and vegetation coverage survey, and the soil physical properties including soil bulk density, soil porosity, field water holding capacity, cohesion and hardness of biocrusts in different developmental stages were determined. The results showed: 1) Fine particles content increased due to the development of biocrusts. The content of coarse sand decreased by 86% while fine sand increased by 45% with biocrusts developing from cyanobacteria dominated to moss dominated (biomass of moss was 4.31±0.12 g/dm2). 2) With the development of biocrusts, soil bulk density and hardness were reduced while field water holding capacity, soil porosity and cohesion were increased significantly. Along with the development of biocrusts, soil bulk density was dropped by 15%. Soil hardness of biocrusts in later development stage was reduced by 68% compared with the early stage. Field water holding capacity was increased to 57%, adding about 36% compared with the early stage, while soil porosity gone up to 58%, increasing by about 14%. Cohesion of biocrusts was 6 or 7 times as much as that of subsurface soil (0-2 cm). 3) Impact of biocrusts on soil physical properties was closely related to biocrusts’biomass. When biomass of moss in biocrusts was to 2.91±0.12 g/dm2, soil physical properties changed no longer significantly. 4) Soil physical properties not only in the layer of biocrusts, but also in the subsurface soil under the biocrusts were affected by the development of biocrusts. In conclusion, the results of our study suggested that soil physical properties were influenced by the development of biocrusts significantly. The study would likely provide scientific basis for the mechanism of soil antierodibility improvement by biocrusts.
[1] Belnap J, Lange O L. Biological Soil Crust: Structure, Function, and Management [M]. Berlin Heidelberg, 2003.
[2] Eldridge D J. Dynamics of cryptogamic soil crusts in a derived grassland in southeastern Australia [J]. Austral Ecology, 2000, 25: 232-240.
[3] Harper K T, Pendleton R L. Cyanobacteria and cyanolichens: Can they enhance availability of essential minerals for higher plants [J]. Great Basin Naturalist, 1993, 53: 59-72.
[4] Belnap J. Soil surface disturbances in cold deserts: Effects on nitrogenase activity in cyanobacterial-lichen soil crusts [J]. Biology and Fertility of Soils, 1996, 23: 362-367.
[5] 肖波, 赵允格, 邵明安. 陕北水蚀风蚀交错区两种生物结皮对土壤理化性质的影响[J]. 生态学报, 2007, 27(11): 4662-4670.
[6] 赵允格, 许明祥, 王全九, 等. 黄土丘陵区退耕地生物结皮对土壤理化性状的影响[J]. 自然资源学报, 2006, 21(3): 441-448.
[7] Lange O L. Photosynthesis and water relations of lichen soil crusts: Field measurements in the coastal fog zone of the Namib Desert [J]. Functional Ecology, 1994, 8(2): 253-264.
[8] Jeffries D L, Link S O, Klopatek J M. CO2 fluxes of cryptogamic crusts I. Response to resaturation [J]. New Phytologist, 1993, 125(1): 163-173.
[9] 赵允格, 许明祥, Belnap J. 生物结皮光合作用对光温水的响应及其对结皮空间分布格局的解译——以黄土丘陵区为例[J]. 生态学报, 2010, 30(17): 4668-4675.
[10] Lange O L, Belnap J, Reichenberger H. Photosynthesis of the cyanobacterial soil crust lichen Collema tenax for arid lands in southern Utah, USA: Role of water content on light and temperature response of CO2 exchange [J]. Functional Ecology, 1998, 12: 195-202.
[11] 张元明, 杨维康, 王雪芹, 等. 生物结皮影响下的土壤有机质分异特征[J]. 生态学报, 2005, 25(12): 3420-3425.
[12] 赵允格, 许明祥, 王全九, 等. 黄土丘陵区退耕地生物结皮理化性状初报[J]. 应用生态学报, 2006, 17(8): 1429-1434.
[13] 王蕊, 朱清科, 卜楠, 等. 黄土丘陵沟壑区生物土壤结皮理化性质[J]. 干旱区研究, 2010, 27(3): 401-408.
[14] Bowker M A, Belnap J, Chaudhary V B, et al. Revisiting classic water erosion models in drylands: The strong impact of biological soil crusts [J]. Soil Biology and Biochemistry, 2008, 40(9): 2309-2316.
[15] 徐杰, 白学良, 田桂泉, 等. 腾格里沙漠固定沙丘结皮层藓类植物的生态功能及与土壤环境因子的关系[J]. 中国沙漠, 2005, 25(2): 234-242.
[16] 范文波, 李小娟. 涂膜法测定黄土结皮容重[J]. 山西水土保持科技, 2001(3): 9-10.
[17] GB 7845—87. 森林土壤颗粒组成(机械组成)的测定[S].
[18] LIU Guo-bin, XU Ming-xiang, Coen R. A study of soil surface characteristics in a small watershed in the hilly, gullied area on the Chinese Loess Plateau [J]. Catena, 2003, 54: 31-44.
[19] 许明祥, 刘国彬, 温仲明, 等. 黄土丘陵区小流域土壤特性时空动态变化研究[J]. 水土保持通报, 2000, 20(1): 21-23.
[20] 肖洪浪, 李新荣, 段争虎,等. 流沙固定过程中土壤-植被系统演变对水环境的影响[J]. 土壤学报, 2003, 40(6): 809-814.
[21] 崔燕, 吕贻忠, 李保国. 鄂尔多斯沙地土壤生物结皮的理化性质[J]. 土壤, 2004, 36(2): 197-202.
[22] 卜楠. 陕北黄土区生物土壤结皮水土保持功能研究. 北京: 北京林业大学, 2009.
[23] ZHAO Yun-ge, XU Ming-xiang, Belnap J. Potential nitrogen fixation activity of different aged biological soil crusts from rehabilitated grasslands of the hilly Loess Plateau, China [J]. Journal of Arid Environments, 2010, 74: 1186-1191.
[24] 冉茂勇, 赵允格, 陈彦芹. 黄土丘陵水蚀区生物结皮土壤抗冲性试验研究[J]. 西北林学院学报, 2009, 24(3): 37-40.
[25] 逯海叶, 李平. 地表温度和土壤颗粒组成对抗剪强度的影响[J]. 内蒙古农业大学学报, 2005, 26(1): 75-78.
[26] 沈晶玉, 周心澄, 张伟华, 等. 祁连山南麓植物根系改善土壤抗冲性研究[J]. 中国水土保持科学, 2004, 2(4): 87-91.
[27] 尹乐, 倪晋仁. 黄土丘陵区土壤抗水蚀能力变化的动态评估[J]. 自然资源学报, 2007, 22(5): 724-734.
[28] 朱显谟. 黄土高原水蚀的主要类型及其有关因素[J]. 水土保持通报, 1982(3): 40-44.
