水保所知识产出(1956---)知识库

土地利用变化在全球碳平衡及气候变化中起着重要作用。目前对黄土高原地区土
壤有机碳库虽然已经进行了大量卓有成效的研究工作，但绝大部分仍是以浅层有机碳
含量或者有机碳库大小作为研究对象，而近期一些研究表明，1m 以下的深层土壤积
聚的有机碳十分可观。该区天然次生林转变为人工林及农田等植被破坏过程中，土壤
有机碳变化的研究还鲜见报道，还不足以科学认识该区土地利用变化对土壤有机碳的
影响方式和程度。本文以黄土丘陵区子午岭为研究区，以天然乔木林、天然灌木林、
人工乔木林、撂荒地、农地 5 种不同土地利用类型为研究对象，以浅层（0~100cm）
土壤为对照，研究深层土壤有机碳储量和有机碳组分对土地利用变化响应的程度、方
式、机理，以及土地利用变化后年限与土壤有机碳的关系。并且对土壤溶解性有机碳
迁移特征及其动态变化进行了研究，进一步了解深层有机碳来源问题。
研究取得以下主要结果：
1. 黄土丘陵子午岭林区天然乔木林、天然灌木林、人工乔木林、撂荒地、农地
0~200cm 有机碳储量分别为 134.65t∙hm -2 、96.23t∙hm -2 、124.98t∙hm -2 、76.03t∙hm -2 、
82.75t∙hm -2 ，深层（100~200cm）土壤有机碳储量分别占 0~200cm 总有机碳储量的 33%、
29%、31%、34%、42%。
2. 不同土地利用类型间 0~200cm 土壤有机碳含量有一定差异，以天然乔木林和
人工林地最高，其次是天然灌木林地，撂荒地和农田土壤有机碳含量最低。不同利用
类型间浅层土壤有机碳含量差异显著，但深层土壤有机碳含量差异不大。
3. 土地利用变化对土壤有机碳储量影响显著，浅层比深层变化更敏感。天然乔
木林转变为人工乔木林、天然乔木林转变为农田、天然灌木林转变为撂荒地及农田四
种土地利用转变方式导致浅层土壤有机碳储量减少幅度为 2%~48%，深层减少幅度为
12%~22%。
4. 天然灌木林地转变为农田土壤有机碳储量随着开垦时间的增长而降低，开垦0~30 年，有机碳含量储量下降较快，降幅为 31%。浅层（0~100cm）土壤有机碳储
量在开垦 30~50 年有略微下降，降幅为 8%，50 年后基本不变。而深层（100~200cm）
土壤有机碳储量变化幅度较小，介于 4%~15%之间。
5. 不同土地利用类型土壤深层（60~200cm）活性有机碳占 0~200cm 活性有机碳
含量的 8%~51%。不同土地利用转变方式不仅对浅层（0~60cm）土壤活性有机碳有
影响，对深层（60~200cm）也有一定影响。天然乔木林转变为人工乔木林、天然乔
木林转变为农田、天然灌木林转变为撂荒地及农田四种土地利用转变方式深层土壤易
氧化性碳减少幅度为 1%~21%；土壤微生物量碳减少幅度为 8%~25%。
6. 土壤溶解性有机碳含量随土壤剖面深度的增加而逐渐降低，与有机碳含量显
著相关；浅层（0~100cm）和深层（100~200cm）溶解性有机碳含量分别占 0~200cm
土层总含量 58%和 42%。灌木林地 DOC 淋溶 10d 后土壤 0~200cm 整个土层 DOC 增
加量增幅为 23%；入渗 30d 的浅层（0~100cm）和深层（100~200cm）DOC 分别仅增
加 5%和 4%。
关键词：深层土壤；有机碳储量；有机碳来源；土地利用变化；黄土丘陵区

Land use change plays an important role in the global carbon balance and climate change. In the
past several years, lots of fruitful researches were conducted on SOC pool in the Loess Plateau region,
although most of the researches focused on shallow organic carbon. Recent studies had shown that huge
amount of SOC was accumulated in deep soil layers (>1m) under ground. So far SOC change with the
deforestration process from natural forest into plantations and cropland was rarely reported in the Loess
Plateau. Limited knowledge was available for understanding the effect of land use change on deep SOC
in the region. In this thesis, taking Ziwuling forest zone of the hilly Loess Plateau as study area,
selecting five land use types including natural woodland, natural shrubland, artificial woodland,
revegetated grassland, cropland as study object, response of SOC and organic carbon fractions to land
use change in deep soil (100-200cm) were explored through field investigation and sampling. For
further understanding of the source of deep organic carbon, on-site infiltration experiment was
conducted to clarify the contribution of dissolved organic carbon to deep SOC. The main results were as
follows:
1. In Ziwuling forest zone on the hilly Loess Plateau, SOC storages of natural woodland, natural
shrub, artificial woodland, revegetated grassland and cropland was 134.65t∙hm -2 , 96.23t∙hm -2 ,
124.98t∙hm -2 , 76.03t∙hm -2 , 82.75t∙hm -2 , respectively. SOC storages in deep soil layers(100-200cm)
contributed 33%, 29%, 31%, 34%, 42% to total SOC storages in the whole profile (0-200cm).
2. SOC content in the whole profile(0~200cm) was varied significantly between different land use
types. Among them, SOC content of natural woodland and artificial woodland was highest, followed by  natural woodland, the lowest was revegetated grassland and cropland. SOC content in shallow layer was
varied significantly between different land use types, however no obvious difference was observed of
SOC content in deep soil layers in all of the investigated land use types.
3. Land use changes showed significant effect on SOC storages, and changes of SOC storages in
shallow soil layers were more sensitive than deep soil layer. From natural woodland to artificial
woodland, natural woodland to cropland, natural shrubland to revegetated grassland and natural
shrubland to cropland, SOC storages in 0-100cm profile decreased by 2%-48%, while the deep layer
decreased by 12%-22%.
4. SOC storage in cropland decreased with the time of conversion from natural shrubland to
cropland . After 30 years of cultivation, SOC content decreased rapidly by 31%. SOC of the shallow
layer (0-100cm) declined slightly after 30-50 years of cultivation by 8%. After 50 years of cultivation,
SOC content keep a relatively stable level. SOC of deep soil layer (100-200cm) declined by 4%-15%
after the landuse change.
5. Soil active organic carbon content in deep soil layer (60-200cm) accounted for 8%-51% and
71%-84% of soil active organic carbon in the profile (0-200cm) under different land-use types. Soil
active organic carbon content in shallow layer (0-60cm) and deep layer (60-200cm) was affected by
landuse changes. From natural woodland to artificial woodland, natural woodland to cropland, natural
shrubland to revegetated grassland and natural shrubland to cropland, labile organic carbon (LOC) in
the deep layer decreased by 1%-21%, and micro biomass carbion (MBC) in the deep layer reduced by
8%-25%.
6. Soil dissolved organic carbon (DOC) content decreased with the increase of depth in soil profile,
which was significantly correlated with SOC content. DOC content in shallow layer (0-100cm) and
deep layer (100-200cm) accounted for 58% and 42% of DOC in the profile (0-200cm), respectively.
After 10d infiltration, DOC content increased by 23% in the profile (0-200cm), while after 30d
infiltration, DOC content in shallow layer (0-100cm) and deep layer (100-200cm) only increased by 5%
and 4%.
Keywords: Deep soil; SOC storage; origin of SOC; land use change; hilly Loess Plateau