水保所知识产出(1956---)知识库

地形因子是黄土丘陵区影响植被生长的关键，微地形通过影响光照福射、温湿
度及土壤养分格局，进一步影响了植物群落的分布和组成。本文以黄土丘陵区安塞试
验站微地形（阳坡坡上、中、下部，坡顶，阴坡坡上、中、下部）尺度下的草地群落
为研究对象，通过野外调查群落组成和地上、地下生物量以及室内分析测定群落植物
叶片、根系及土壤化学计量学特征，探究黄土丘陵区群落生物学及化学计量学特征随
微地形的变化特征，主要结论如下：
（1 ）研究区内草地群落主要由菊科、禾本科和豆科的物种组成，阴坡物种较阳
坡丰富。群落地上、地下生物量、根系年生长量分别为：164.12 g∙m -2 、1044.87 g∙m -2 、
731.77 g∙m -2 ∙a -1 ，且在不同坡向的大小顺序都为：阴坡>阳坡>坡顶。根系生长主要集
中在 0~20 cm，且从上到下逐渐减小。
（2 ）研究区土壤有机碳（1.20~12.78 g∙kg -1 ）、全氮（0.14~0.94 g∙kg -1 ）、全磷
（0.14~0.63 g∙kg -1 ）、全钾（8.32~11.53 g∙kg -1 ）、速效钾（40.82~86.75 mg∙kg -1 ）、铵
态氮（3.53~7.23 mg∙kg -1 ）、硝态氮（12.25~27.91 mg∙kg -1 ）、速效磷（0.43~0.92 mg∙kg -
1 ）和土壤含水量（3.91~12.2%）基本都在阴坡大于阳坡，并且在阴阳坡的坡下部富集。
土壤 C/N 比值（4.85~19.38）、C/P 比值（3.64~27.66）、N/P 比值（0.50~1.78）、C/K
比值（0.22~1.13）也随着微地形的变化而变化。方差分析表明，坡向和坡位及其交互
作用都对土壤养分和水分有显著影响。相关分析表明，土壤水分和养分与群落生产力
之间密切相关。
（3 ）研究区草本群落叶片 C、N、P、K 含量的平均值分别为：433.47、24.84、
1.61、16.15 g∙kg -1 。叶片 C/N、C/P、N/P、C/K 化学计量比的平均值分别为：18.18、
320.36、17.41、29.69，叶片 N/P 比值表明黄土丘陵区植物生长更易受 P 限制。根系
C、N、P、K 含量的平均值分别为：380.05、9.07、0.31、5.46 g∙kg -1 ，根系 C/N、C/P、
N/P 化学计量比的平均值分别为：49.61、1326.64、30.73。研究发现研究区草地群落
叶片及根系 C、N、P、K 含量在坡向梯度上表现为阴坡大于阳坡。（4） ）植物与土壤作为生物地球化学循环的不同环节，两者之间必然存在着联系。
相关分析表明：0~20、20~50、50~80、80~100 cm 四个分层的土壤 C、N、P、K 含量
与叶片及根系化学计量特征之间都有不同程度的相关关系，特别是表层土壤 C、N、
P、K 含量与叶片及根系 C、N、P、K 含量基本都呈显著正相关关系。
（5 ）草地群落添加 N 肥和 N+P 复合肥后显著增加了地上生物量而降低了地下
生物量，且施肥增加了叶片 N、P 含量，改变了叶片 N/P 值，但根系 C 和 K 含量对
施 N 肥和 N+P 复合肥后响应不大。施肥同样也改变了土壤养分含量和土壤化学计量
特征，尤其是施肥大大增加了土壤速效 N、P 养分含量。
关键词: 微地形尺度；草地群落；生物量；化学计量学特征

Terrain is the key factor affect the growth of vegetation in the loess hilly region.Tiny
terrain influence the pattern of light radiation, the temperature and humidity and soil nutrient,
further influence the distribution and composition of plant community. In order to analyze
the impact of tiny terrain on grassland plant community structure and function, species
composition, aboveground and belowground biomass, and annual fine root production at
different slope aspect (sunny slope and shady slope) and different slope position (top, upper,
middle and lower) were investigated in the hilly Loess Plateau region. The main points as
follows:
(1)The results showed that grassland communities were mainly composed of plants
species belonging to Compositae, Poaceae and Leguminosae in research region. The
aboveground and belowground biomass and annual fine root production of community were
164.12 g∙m -2 , 1044.87 g∙m -2 and 731.77 g∙m -2 ∙a -1 , respectively. Aboveground biomass,
belowground biomass and annual fine root production of community were in the order of
shady slope>sunny slope>top slope. Fine root mainly concentrated in the 0~20 cm top soil
layer and decreased with soil depth.
(2) The average soil organic carbon (1.20~12.78 g∙kg -1 ), total N (0.14~0.94 g∙kg -
1 ）,total P（0.14~0.63 g∙kg -1 ）,total K (8.32~11.53 g∙kg -1 ), available K (40.82~86.75 mg∙kg -
1 ), ammonium N (3.53~7.23 mg∙kg -1 ), nitrate N (12.25~27.91 mg∙kg -1 ), available P
(0.43~0.92 mg∙kg -1 ) and soil water content (3.9~12.2%) are basicly greater in shady slope
than sunny slope, and lower in the upper slope than lower slope. Soil C/N (4.85~19.38), C/P
(3.64~27.66), N/P (0.50~1.78), the C/K (0.22~1.13) also changes with the tiny terrain.
Variance analysis showed that slope direction and slope position and their interactions all  had a significant effect on soil nutrients and soil water content. Correlation analysis showed
the soil nutrients and soil moisture correlated with the community productivity.
(3) The average leaf C, N, P, K content were 433.47, 24.84, 1.61, 16.15 g∙kg -1
respectively, the average root C, N, P, K content were 380.05, 9.07, 0.31, 5.46 g∙kg -
1 respectively. Leaf C/N, C/P, N/P and C/K stoichiometric were 18.18, 320.36, 17.41, 29.69
respectively, Leaf N/P ratio shows that plants restricted by P in loess hilly region. root C/N,
C/P, N/P stoichiometric were 49.61, 1326.64, 30.73 respectively. Leaf and root C, N, P
content in different slope aspect were in the order of shady slope > sunny slope > top slope.
(4)Plant and soil as the different part of biogeochemical cycle, there must exist the
contact. Correlation analysis showed that between 0~20, 20~50, 50~80, 80~100 cm soil
nutrient and leaf and root stoichiometric characteristics were correlated. Especially the soil
C, N, P, K content in 0~20 cm with leaf and root C, N, P, K content are significantly positive
correlation (P < 0.05).
(5) The aboveground biomass significantly increased and the belowground biomass
decreased after fertilizing, the leaf N, P content also increased after fertilizing, and
fertilization also changed the leaf N/P value. Root C and K content are not significantly
changed after fertilizing. Fertilization also changed the soil nutrient content and soil
chemical characteristics, especially significantly increased soil available N, P nutrient
content.
Key Words: Tiny terrain gradient; Grassland communities; Biomass; Ecological
stoichiometry