水保所知识产出(1956---)知识库

凋落物是指在生态系统内，由地上植物组分产生并归还到地面，作为分解者的物
质和能量来源，借以维持生态系统功能的所有有机质的总称。凋落物的分解是生态系
统养分循环的关键过程之一，对其分解过程的研究有助于理解生态系统的生物地球化
学循环和土壤有机质的形成。黄土高原地区由于恶劣的自然环境和长期的开垦及不合
理利用，导致这一地区自然植被遭到严重破坏，土壤贫瘠，生态环境极度脆弱。近年
来，黄土高原通过一系列的退耕还林还草、封山育林育草、禁伐禁牧等工程，植被得
到了恢复，生态环境有所改善。随着这些工程的开展，植物凋落物就成为了这些地区
主要的有机物质及养分来源。因此研究黄土高原地区植物凋落物的分解状况和生态系
统管理具有重要的理论和指导意义。
本文选取黄土高原种植较为广泛的几种植物叶凋落物为研究对象，采用室内恒温
培养法研究了不同叶凋落物的分解特征和其进入土壤后对土壤有机碳、氮、磷含量的
影响，以及不同温度、土壤含水量、氮添加对叶凋落物分解特征的影响，最后研究了
混合叶凋落物的分解特征。研究主要获得以下结论：
1. 不同叶凋落物加入土壤后，CO 2 释放速率表现为相似的变化趋势：培养初期 CO 2
释放速率较大，随后进入相对缓慢且稳定的分解期。CO 2 累积释放量以玉米叶凋落物
最大，油松叶凋落物最小。不同叶凋落物质量随着时间推移均不断减小。所研究 10
种叶凋落物的分解速率主要集中在 0.47 -1.20 kg kg -1  a -1 之间，差异较大。通过对凋落
物初始底物质量与其干重剩余率进行相关分析，结果表明：叶凋落物分解速率与全碳、
磷 钾含量相关（P<0.01）。不同叶凋落物分解过程中 N、P 含量呈上升趋势，而 C、
K 含量变化不一致。不同叶凋落物养分释放模式具有明显的阶段性。10 种叶凋落物
在分解过程中 C、N 大致呈释放模式，不同叶凋落物 P、K 元素释放动态存在显著差
异。
2. 温度升高促进了叶凋落物分解过程中 CO 2 的释放。叶凋落物的 CO 2 累积释放量在
25 ℃条件下比 15 ℃培养条件下高 2.4-25.3%。高的土壤含水量也促进了叶凋落物
CO 2 的释放，80%田间持水量条件下叶凋落物 CO 2 累计释放量比 40%田间持水量条件
下高 9.5 -17.7%。氮添加对不同叶凋落物的 CO 2 累积释放量的影响不同：氮添加有利
于油松叶凋落物后期 CO 2 释放，但抑制了针茅叶凋落物 CO 2 释放，对刺槐和杨树叶凋落物 CO 2 释放影响没有差异。温度和土壤含水量的升高促进了叶凋落物的分解，
氮添加抑制了刺槐、针茅、杨树叶凋落物的分解。温度升高显著降低了大部分叶凋落
物分解前期的碳残留率，促进了氮释放，促进了部分叶凋落物磷和钾的释放，对其他
叶凋落物养分释放存在分解阶段的差异。水分和氮添加处理对叶凋落物养分释放的影
响与叶片来源和养分类型有关。
3. 刺槐-针茅、刺槐-杨树、针茅-杨树组合叶凋落物混合能够促进 CO 2 释放，其他组
合在不同分解阶段影响不同。分解 12 个月时，6 种叶凋落物组合的都没有显著的凋
落物混合效应，但分解初期除油松-针茅组合外，其它凋落物混合都有显著的正效应。
凋落物混合对分解过程中养分元素释放的影响在不同凋落物组合中表现的不尽相同，
而且随着分解的进行，影响的大小和方向也随之变化。分解 12 个月时，混合叶凋落
物土壤有机碳、氮含量均小于其中任一单种叶凋落物，其平均值降低了 16.3%、13.9%，
但土壤全磷含量增加了 3.4%。
关键词：叶凋落物；分解；碳；氮；温度；混合叶凋落物

Litter refers to the organic matter which are produced by plant components and
then returned to the ground, acting as the source of matter and energy for
decomposers so as to maintain the ecosystem functions. The leaf decomposition and
carbon flux process play an important role in biogeochemical cycling. Therefore, the
study of the litter decomposition process contributes to comprehending
biogeochemical cycle and formation of soil organic matter in ecosystem. Due to
severe natural environment and long-term reclamation and irrational utilization hereof,
loess plateau has been faced with heavily damaged natural vegetation, poorer soil as
well as extremely weak ecosystem. In recent years, Chinese government has initated a
big ecological project to reestablish the ecology by grain for green. With the process
of the above-mentioned projects, plant litter becomes the main source of organic
matter and nutrients in this region. Therefore, study of litter decomposition conditions
and ecosystem management has theoretical and guiding significance.
In this paper, leaf litter of several plants widely planted in loess plateau were
chosen as the object of study and indoor constant temperature incubation was chosen
to study different leaf litter’s decomposition characteristics and its impact on soil
organic carbon, nitrogen and phosphrous content in soil, impact of different
temperature, soil water content and nitrogen addition on leaf litter’s decomposition
characteristics, and in the end, decomposition characteristics of mixing litter leaves.
The main conclusions are as follows:
1. After added to soil, the CO 2  release rate of different leaf litters showed similar trend,
which showed relatively high CO 2  release rate at the initial stage followed by
relatively slow and steady decomposition process. Maize leaf litter had the maximum
calculative amount of CO 2  release, while Pine tabulaeformis the minimum. The mass
of different leaf litters decreased over time. The decomposition rate of 10 types of leaf  litters involved in this study was mainly in the range of 0.47 -1.20 kg kg -1  a -1 . Based
on relevant analysis of litters’ initial substrate mass and residual rate of dry weight,
results showed that decomposition rate of leaf litters is related to all carbon,
phosphorus and potassium content（P<0.01）. The content of N and P was on the rise,
while change of content of C and K were different during the decomposition of
different leaf litters. Modes of nutrient release of different leaf litters during various
stages. C and N in the decomposition of 10 types of leaf litters is approximately in the
mode of release, while P and K of different leaf litters had significant difference in
dynamic condition.
2. Temperature rise could accelerate CO 2  release during decomposition of leaf litters.
Calculative amount of CO 2  release at 25 ℃ was 2.4-25.3% larger than that at 15 ℃.
High soil water content in soil could accelerate CO 2  release of leaf litters. Calculative
amount of CO 2  release in condition of 80% field capacity was 9.5 -17.7% higher than
that of 40% field capacity. The impact of nitrogen addition on calculative amount of
CO 2  release varied with different leaf litters. Nitrogen addition could accelerate CO 2
release of Pine tabulaeformis at later stage and inhibit that of stipa capillata Linn. ,
while had no different impact on CO 2  release of Black Locust and Populus L. leaf
litters. A rise of temperature and water content in soil could accelerate decomposition
of leaf litters and nitrogen addition could accelerate decomposition of Black Locust,
stipa capillata Linn. and Populus L. leaf litters. Temperature rise could significantly
lower residual rate of C at the early stage of decomposition of most leaf litters,
promote N, P and K release of part of the leaf litters. Impact of water content and
nitrogen addition on nutrient release of leaf litters was related to source of leaves and
types of nutrient.
3. Mixing of leaf litters in group of Black Locust - stipa capillata Linn. , Black Locust
– Populus L. , stipa capillata Linn. - Populus L. , could accelerate CO 2  release, while
the impact of mixture in other groups varied with different decomposition stage. At
month 12, all litter mixtures did not have effect on the mass remaining，but most litter
mixtures have a significant positive effect at initial. Impact of mixing of litters on
nutrient release in decomposition were not the same in different groups of litters, and ,
degree of impact and tendency changed over the period of decomposition. After 12 months of decomposition, the amount of organic carbon and nitrogen content in soilin
mixing leaf litters was lower than that in any single leaf litter, with average amount
lower 16.3% and 13.9%, while phosphorus content in soil increased 3.4%.
Key words: leaf litter; decomposition; carbon; nitrogen; temperature; mixing leaf
litters