ISWC OpenIR  > 水保所知识产出(1956---)
黄土高原不同侵蚀类型区 生物结皮固氮潜力研究
明 姣
Subtype硕士
Thesis Advisor许明祥
2013-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword生物结皮 侵蚀类型区 固氮活性 乙炔还原法 固氮潜力
Abstract

黄土高原地区退耕还林还草工程实施后,以藻类、苔藓及地衣等先锋物种为主的
生物结皮广泛发育,盖度可达 70%左右,可能是该区土壤氮素的重要来源之一。本文
以黄土高原地区不同侵蚀类型区(本文简称不同侵蚀区)发育至稳定阶段的生物结皮
为研究对象,通过野外调查和室内分析研究了黄土高原水蚀区、水蚀风蚀交错区(简
称交错区)及风蚀区生物结皮的固氮活性对水、温变化的响应,明确了生物结皮固氮
活性对环境变化的响应及其差异,在此基础上,通过数理统计分析及模型估算,探明
黄土高原不同侵蚀区生物结皮对土壤中氮素积累的贡献,揭示在以植被恢复为主的生
态恢复过程中生物结皮的生态功能及其在土壤肥力恢复中的潜力及作用,为科学评估
黄土高原退耕还林草工程的环境效应提供科学依据。所得主要结论如下:
(1 1 ) 黄土高原三个侵蚀类型区 生物结皮固氮活性差异显著。
由于不同侵蚀区生物结皮对环境温度的适应性导致其固氮活性在不同的温度条
件下表现不同,当温度低于 25℃时,各侵蚀区生物结皮固氮活性表现为交错区>水蚀
区>风蚀区,而当温度在高于 35℃时,各侵蚀区生物结皮固氮活性则表现为为水蚀区>
交错区>风蚀区。在各自最适水温条件下,三个侵蚀区生物结皮固氮活性表现为:水
蚀区(126.4umol·m -2 ·h -1 )>交错区(37.4umol·m -2 ·h -1 )>风蚀区(5.6 umol·m -2 ·h -1 )。
(2 2 ) 不同侵蚀类型区生物结皮固氮活性对水温变化的响应不同,生物结皮固氮
所需的最适温度及最适土壤水分含量 有明显 差异。
当温度一定时,三个侵蚀区生物结皮固氮活性对水分变化的响应略有差异。其中
水蚀区生物结皮固氮活性在结皮层土壤含水量为 100%~40%田间持水量时差异不显
著,含水量低至 20%田间持水量时生物结皮固氮活性显著降低;交错区结皮层土壤含
水量在 60%~40%田间持水量时,生物结皮固氮活性最高,当含水量为 100%~80%
及 20%田间持水量时,生物结皮的固氮活性显著降低;风蚀区生物结皮固氮活性对水
分变化敏感,结皮层土壤含水量低至 80%田间持水量时生物结皮固氮活性显著降低,
含水量在 80%~40%田间持水量之间时,固氮活性差异不显著,当含水量降低至 20%
田间持水量时生物结皮固氮作用停止。
在适当的水分条件下,三个侵蚀区生物结皮固氮活性对温度变化的响应也不同。
三个侵蚀类型区生物结皮固氮活性在 5~45℃范围内,随着温度的上升,生物结皮固
氮活性均呈现先升高后降低的趋势,但不同侵蚀区生物结皮固氮活性达到最高时的温度条件不同。水蚀区、交错区及风蚀区,其固氮作用的最适温度依次为 35℃、25℃、
15℃。
(3 3 ) 生物结皮可显著提高结皮层土壤氮素含量,三个侵蚀类型区土壤氮素含量
在剖面分布上表现为结皮层土壤全氮、碱解氮、铵态氮及微生物氮含量显著高于下
层土壤氮素含 量,而结皮层土壤硝态氮含量与下层差异不显著;
从剖面上看,黄土高原水蚀区、交错区及风蚀区在生物结皮的影响下结皮层土壤
全氮(1.16~1.29 g·kg -1 )、碱解氮(80.3~115.8mg·kg -1 )、铵态氮(3.05~9.58mg·kg -1 )
及微生物氮(425.5~462.3mg·kg -1 )的含量显著高于 0-10cm 土层;而结皮层硝态氮
(0.52~2.76mg·kg -1 )含量与 0-10cm 土层没有显著差异。
从降雨期看,以交错区为例,雨季前(4-5 月)、雨季中(7-8 月)、雨季末(10-11
月)三个降雨时期,结皮层、0-2cm、2-5cm、5-10cm 土层土壤全氮、碱解氮及微生
物氮含量差异不显著。而在剖面上均表现为结皮层土壤全氮、碱解氮及微生物氮含量
显著高于 0-10cm 土层土壤各形态氮素含量;
(4 4 )各形态氮素 在区域之间分布不同, 结皮层土壤全氮、碱解氮及微生物氮含
量在三个侵蚀类型区之间差异不显著,而结皮层土壤铵态氮及硝态氮含量及下层土
壤铵态氮及硝态氮含量在三个侵蚀类型之间均差异显著;
从区域上看,结皮层土壤全氮、碱解氮及微生物氮含量在三个侵蚀区之间差异不
显著,而下层 0-10cm 土壤全氮、碱解氮及微生物氮含量在风蚀区显著低于水蚀区及
交错区;风蚀区结皮层硝态氮含量显著高于交错区及水蚀区结皮层硝态氮含量,
0-10cm 土层土壤硝态氮含量则是风蚀区及交错区高于水蚀区;交错区结皮层土壤铵
态氮含量显著低于水蚀区及风蚀区土壤铵态氮含量,而 0-10cm 土层则相反,交错区
铵态氮含量显著高于风蚀区及水蚀区土壤铵态氮含量。
(5 5 ) 生物结皮对土壤氮素累积有重要贡献。水蚀区、交错区及风蚀区生物结皮
通过固氮作用向土壤中输入的全氮量分别可达10.39、6.5、0.83kg·ha -1 ·a -1 ,尽管三个
侵蚀类型区生物结皮土壤全氮年增量分别为5.36、3.54、4.90kg·ha -1 ·a -1 。
关键词:生物结皮;侵蚀类型区;固氮活性;乙炔还原法;固氮潜力

Other Abstract

Biological soil crusts (biocrusts) that constituted by pioneer organismes such as algae,
cyanobactira, mosses and lichens were extensively formed in the Loess Plateau region,
China, which cover up 70% soil surface in rehabilitated grasslands after the “Grain for
Green” eco-project was implementated in the region., Biocrusts may be an important part
of nitrogen source for its nitrogen fixed organisms. In the paper, the study was conducted
to determine the potential nitrogenase activity (NA) of biocrusts from the revegetated
grasslands in different erosion type regions (water erosion region, wind-water crisscross
erosion regions and the wind erosion region) on the Loess Plateau, as well as their
responses to variation in moisture and temperature. Then the statistical analysis and
simulation calculation were used to estimate the amount of nitrogen fixation by biocrusts.
The purpose was to reveal the nitrogen contribution to soil of the biological soil crust,
provide scientific basis for vegetation restoration in this area. The results are as follows:
(1)Biocrusts are ubiquitous living covers in all the three erosion type regions in
the Loess Plateau region, NAs of the biocrusts showed siginificant differences between
the three three erosion type regions.
The NAs of biocrusts of the three erosion type regions were highly variable. Under
the given the proper temperature and moisture conditions, the average of NA of biocrusts
from water erosion, water-wind crisscross erosion and wind erosion regions were 126.4,
37.4 and5.6μmol  C 2 H 4 ·m -2 ·h -1 .
(2)The NAs for biocrusts of the three erosion type regions and its responses to
hydrothermic factors were different from each other.
The NAs for biocrusts of the three erosion type regions and its responses to
hydrothermic factors were different when measured under different hydrothermical
conditions. No significant difference was found in NAs for biocrusts from water erosion
regions under 100%~40% field water-holding capacity. However, the NA show a dramastic decline when the moisture decreased to 20% field water-holding capacity. The
NA of biocrusts from the wind-water crisscross erosion regions showed a dramastic
increase when soil moisture was varied between 60% and 40% field water-holding capacity,
while it showed unsignificant difference for soil moisture 100%~80% and 20% field
water-holding capacity. However, NAs of biocrusts in the wind erosion region showed a
dramatic decline when soil moisture was lower than 100% field water-holding capacity, the
nitrogen fixation of biocrusts was suspended when the moisture decreased to 20% field
water-holding capacity.
The optimal temperatures for biocrusts nitrogen fixation of the three erosion type
regions were respectively 35℃(water erosion region), 25℃(wind-water crisscross erosion
regions) and 15℃(wind erosion region) when measured under adequate moisture
conditions.
(3) Soil nitrogen content was significantly improved for the formation of
biocrusts, but the distribution of nitrogen in soil profiles in the three fifferent erosions
types regions were different.
The contents of soil total nitrogen (1.16~1.29g·kg -1 ), alkali-hydrolyzable nitrogen
(80.3~115.8mg·kg -1 ), ammonium nitrogen (3.05~9.58mg·kg -1 ) and microbial nitrogen
(425.5~462.3mg·kg -1 ) in the biocrusts layers was significantly higher than that in the
0-10cm layers in the three different erosion type region; The nitrate (0.52~2.76mg·kg -1 )
content of biocrusts layers have no significant difference with the 0-10cm soil layer.
Soil total nitrogen, alkali-hydrolyzable nitrogen and microbial nitrogen contents of
biocrusts did not show significantly difference between before the rainy season
(April-May), rainy season (July-August) and the end of the rainy season (October-
November) in the wind-water crisscross erosion region. And the soil total nitrogen,
alkali-hydrolyzable nitrogen and microbial nitrogen contents of every soil layers among
the three erosion type region were not significantly different.
(4) The distribution pattern of the nitrogen forms were different between the
three erosion regions. No significant difference was found in soil total nitrogen,
alkali-hydrolyzable nitrogen and microbial nitrogen contents in biocrusts layers
between the the three erosion types regions. Soil nitrate nitrogen and ammonium
nitrogen in biocrusts layers and in the soil beneath showed a significant difference between
the three erosion regions.
At the regional scale, the difference of the total nitrogen, alkali-hydrolyzable nitrogen
and microbial nitrogen contents of biocrusts layers among the three erosion types area was   not significant, the total nitrogen, alkali-hydrolyzable nitrogen and microbial nitrogen
contents in the wind erosion type region were significantly lower than that in the
wind-water crisscross erosion region and water erosion type region. While the soil nitrate
nitrogen and ammonium nitrogen is not the case, the nitrate nitrogen contents of biocrusts
layer in wind erosion type region was higher than that in wind-water crisscross erosion
region and water erosion type region, but the nitrate nitrogen contents of 0-10cm soil
layers in the wind erosion crisscross region and wind-water crisscross erosion region were
higher than that in the wind erosion region; Meanwhile, the ammonium nitrogen contents
of biocrusts layers in wind-water crisscross erosion region was lower than that in water
crisscross erosion region and water erosion type region, but the ammonium nitrogen
contents of 0-10cm soil layers were completely opposite. 
(5) Biocrusts plays an importang role on soil nitrogen accumulaiton.
Biocrusts-fixed nitrogen in the three different erosion types region were up to 0.83,
6.51, 10.39kg·ha -1 ·a -1 , while soil total nitrogen increase rate were 5.36, 3.54,
4.90kg·ha -1 ·a -1 .
KEY WORDS:Biological soil crusts;Different erosion regions;Acetylene reduction
assays(ARA);Nitrogenase activity;Environmental factors

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8960
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
明 姣. 黄土高原不同侵蚀类型区 生物结皮固氮潜力研究[D]. 北京. 中国科学院研究生院,2013.
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