荒漠区地表凋落物分解对季节性降水增加的响应

doi:10.3724/SP.J.1258.2012.00471

摘要/Abstract

摘要：

为探讨季节性降水增加对荒漠生态系统凋落物分解的影响, 在古尔班通古特沙漠南缘, 选择粗柄独尾草(Eremurus inderiensis)叶、尖喙牻牛儿苗(Erodium oxyrrhynchum)叶、尖喙牻牛儿苗茎、沙漠绢蒿(Seriphidium santolinum)茎4种凋落物样品, 在2009-2011年研究了模拟季节降水增加(冬春增雪、夏季增水)和自然降水处理下凋落物的分解。持续2年的分解实验表明: (1)各组分凋落物的质量损失过程可以用负指数衰减方程较好地拟合(R²> 0.90); 经过637天的分解, 各组分凋落物质量残留率在自然降水、冬春增雪、夏季增水处理下均无显著性差异(p > 0.05)。粗柄独尾草叶、尖喙牻牛儿苗叶、尖喙牻牛儿苗茎、沙漠绢蒿茎在自然降水处理下的质量残留率分别为40.59%、35.50%、36.00%和63.96%; (2)各组分凋落物的质量残留率与N残留率显著正相关, 凋落物N的损失快于其质量损失, 且初始N含量与分解速率显著正相关(r = 0.60, p = 0.038), C/N解释了71%的地面凋落物分解速率。研究表明, 季节性的短暂降水增加对荒漠区地表凋落物分解没有显著影响, 凋落物初始化学组成是预测荒漠区地表凋落物分解的重要因素。

关键词: 干旱区, C:N, 质量损失, 养分输入, 降水脉冲

Abstract:

Aims The decomposition of plant litter is a complex process mediated by biotic and abiotic factors. However, litter decomposition and its controlling factors are still controversial and unclear in arid and semi-arid ecosystems. In arid lands, precipitation has inconsistent effects on litter decomposition and nitrogen dynamics. Our objectives were to: (1) examine litter decomposition and nitrogen dynamics in litter with water additions at different seasons and (2) determine the factors critical to surface litter decomposition in arid lands.
Methods We used the litter-bag method to investigate leaf decomposition of Eremurus inderiensis and Erodium oxyrrhynchum and stem decomposition of Erodium oxyrrhynchum and Seriphidium santolinum in China’s Gurbantunggut Desert. We placed litterbags filled with those litters on soil surface in October 2009. We added snow from December to March of the next year and water from June to August. Litterbags were collected in April, July and October of 2010 and in April and July of 2011. Mass loss, carbon, nitrogen and phosphorus content, and decomposition rates of litter were analyzed at each decomposition stage. In addition, soil water content at 0-10 cm soil depth was measured at 10-day intervals from April to November.
Important findings The mass loss of different litters fit the exponential decay model (R²> 0.90). After 637 days of decomposition, no significant differences were observed among natural precipitation, snow addition and water addition treatments, and the mass remaining for leaves of Eremurus inderiensis and Erodium oxyrrhynchum and stems of Erodium oxyrrhynchum and Seriphidium santolinum with natural precipitation were 40.59%, 35.50%, 36.00% and 63.96%, respectively. The mass remaining was positively related to nitrogen remaining, which meant the litter nitrogen loss was faster than mass loss. Correlation analysis showed that decay rates were positively related to initial nitrogen content and inversely related to initial C/N. Initial C/N could explain 71% of the variation in decomposition rate. Results suggest that water addition in different seasons will not promote decomposition of surface litters, and initial litter chemical composition is critical to surface litter decomposition in the Gurbantunggut Desert.

Key words: arid land, carbon : nitrogen ratio (C:N), mass loss, nutrients input, precipitation pulse

赵红梅, 黄刚, 马健, 李彦, 周丽. 荒漠区地表凋落物分解对季节性降水增加的响应. 植物生态学报, 2012, 36(6): 471-482. DOI: 10.3724/SP.J.1258.2012.00471

ZHAO Hong-Mei, HUANG Gang, MA Jian, LI Yan, ZHOU Li. Responses of surface litter decomposition to seasonal water addition in desert. Chinese Journal of Plant Ecology, 2012, 36(6): 471-482. DOI: 10.3724/SP.J.1258.2012.00471

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链接本文: https://www.plant-ecology.com/CN/10.3724/SP.J.1258.2012.00471

https://www.plant-ecology.com/CN/Y2012/V36/I6/471

图/表 11

图1 古尔班通古特沙漠月降水量和月平均气温的变化(2009年10月-2011年8月)。

Fig. 1 Variations of monthly precipitation and monthly average air temperature in the Gurbantunggut Desert from October 2009 to August 2011.

图2 不同处理下0-10 cm土层的土壤含水量的变化(平均值±标准误差)。

Fig. 2 Changes of soil water contents in 0-10 cm soil layer under different treatments (mean ± SE).

表1 凋落物的初始化学组成(平均值±标准偏差)

Table 1 Initial chemical composition of litters (mean ± SD)

凋落物类型 Litter type	C (%)	N (%)	P (%)	C/N	C/P
粗柄独尾草叶 Eremurus inderiensis leaf	36.627 ± 4.504^a	0.694 ± 0.055^a	0.064 ± 0.001^a	53 ± 8^a	571 ± 76^a
尖喙牻牛儿苗叶 Erodium oxyrrhynchum leaf	40.786 ± 4.686^a	2.117 ± 0.037^b	0.143 ± 0.001^b	19 ± 2^b	285 ± 33^b
尖喙牻牛儿苗茎 Erodium oxyrrhynchum stem	40.614 ± 3.005^a	1.039 ± 0.134^c	0.132 ± 0.016^b	39 ± 3^c	309 ± 11^b
沙漠绢蒿茎 Seriphidium santolinum stem	41.260 ± 5.104^a	0.540 ± 0.015^d	0.063 ± 0.0002^a	76 ± 8^d	657 ± 83^a

图3 不同处理下凋落物质量残留率的变化。 A, 粗柄独尾草叶。B, 尖喙牻牛儿苗叶。C, 尖喙牻牛儿苗茎。D, 沙漠绢蒿茎。Treat.表示处理, Time表示分解时间, Tr × Time表示处理与分解时间的交互效应, 星号和ns表示处理、分解时间及处理与分解时间交互效应的差异显著性(***, p < 0.001, ns, p > 0.05)。

Fig. 3 Changes of litter mass remaining under different treatments. A, Eremurus inderiensis leaf. B, Erodium oxyrrhynchum leaf. C, Erodium oxyrrhynchum stem. D, Seriphi- dium santolinum stem. Asterisks and ns are the statistical significance for the treatments (Treat.), decomposition time (Time) and interaction of treatment and decomposition time (Tr × Time) (***, p < 0.001, ns, p > 0.05).

表2 凋落物质量残留率的负指数方程

Table 2 Negative exponential equations of mass remaining of litters

凋落物类型 Litter type	处理 Treatment	负指数衰减模型 Negative exponential decomposition model	决定系数R² Determination coefficient
粗柄独尾草叶 Eremurus inderiensis leaf	对照 Control	y = 93.482e^-0.521^t	0.960
	冬春增雪 Snow addition in winter-spring	y = 96.339e^-0.560^t	0.977
	夏季增水 Water addition in summer	y = 93.478e^-0.510^t	0.979
尖喙牻牛儿苗叶 Erodium oxyrrhynchum leaf	对照 Control	y = 95.944e^-0.577^t	0.980
	冬春增雪 Snow addition in winter-spring	y = 91.872e^-0.491^t	0.942
	夏季增水 Water addition in summer	y = 98.261e^-0.651^t	0.989
尖喙牻牛儿苗茎 Erodium oxyrrhynchum stem	对照 Control	y = 105.036e^-0.556^t	0.943
	冬春增雪 Snow addition in winter-spring	y = 103.101e^-0.485^t	0.972
	夏季增水 Water addition in summer	y = 102.283e^-0.541^t	0.989
沙漠绢蒿茎 Seriphidium santolinum stem	对照 Control	y = 98.943e^-0.238^t	0.976
	冬春增雪 Snow addition in winter-spring	y = 98.605e^-0.223^t	0.977
	夏季增水 Water addition in summer	y = 102.283e^-0.290^t	0.988

表3 凋落物质量残留率的ANOVA结果

Table 3 ANOVA results of mass remaining in litters

因素 Factor	平方和 Sum of squares	自由度 df	均方 Mean square	F	p
分解时间 Decomposition time	37 670.821	3.5	10 856.361	407.531	<0.001
物种 Species	27 082.289	3.0	9 027.430	152.324	<0.001
处理 Treatment	227.389	2.0	113.694	1.918	0.159
分解时间×物种 Decomposition time × species	1 861.668	10.4	178.838	6.713	<0.001
分解时间×处理 Decomposition time × treatment	353.313	6.9	50.911	1.911	0.072
物种×处理 Species × treatment	170.258	6.0	28.376	0.479	0.820
分解时间×物种×处理 Decomposition time × species × treatment	839.802	20.8	40.337	1.514	0.081

图4 不同处理凋落物N残留率的变化。 A, 粗柄独尾草叶。B, 尖喙牻牛儿苗叶。C, 尖喙牻牛儿苗茎。D, 沙漠绢蒿茎。Treat.表示处理, Time表示分解时间, Tr × Time表示处理与分解时间的交互效应, 星号和ns表示处理、分解时间及处理与分解时间交互效应的差异显著性(**, p < 0.01, ***, p < 0.001, ns, p > 0.05)。

Fig. 4 Changes of N remaining in litters under different treatments. A, Eremurus inderiensis leaf. B, Erodium oxyrrhynchum leaf. C, Erodium oxyrrhynchum stem. D, Seriphidium santolinum stem. Asterisks and ns are the statistical significance for the treatments (Treat.), decomposition time (Time) and interaction of treatment and decomposition time (Tr × Time) (**, p < 0.01, ***, p < 0.001, ns, p > 0.05).

图5 不同处理下凋落物质量残留率与N残留率的关系。 A, 粗柄独尾草叶。B, 尖喙牻牛儿苗叶。C, 尖喙牻牛儿苗茎。D, 沙漠绢蒿茎。r1、r2和r3分别表示对照、冬春增雪和夏季增水处理下线性回归拟合结果的相关系数(*, p < 0.05; **, p < 0.01)。

Fig. 5 Relationships between litter mass remaining and nitrogen (N) remaining under different treatments. A, Eremurus inderiensis leaf. B, Erodium oxyrrhynchum leaf. C, Erodium oxyrrhynchum stem. D, Seriphidium santolinum stem. r1, r2 and r3 represent correlation coefficient using simple linear regression to fit the control, snow addition in winter-spring and water addition in summer, respectively (*, p < 0.05; **, p < 0.01).

图6 凋落物质量残留率与N残留率的关系。r1、r2、r3和r4分别表示粗柄独尾草叶、尖喙牻牛儿苗叶、尖喙牻牛儿苗茎、沙漠绢蒿茎线性回归拟合结果的相关系数。星号表示质量残留率与N残留率的相关性(**, p < 0.01)。

Fig. 6 Relationships between litter mass remaining and litter nitrogen remaining. r1, r2, r3 and r4 represent correlation coefficients using simple linear regression to fit the Eremurus inderiensis leaf, Erodium oxyrrhynchum leaf, Erodium oxyrrhynchum stem and Seriphidium santolinum stem, respectively. Asterisks denote significant differences between litter mass remaining and nitrogen remaining (**, p < 0.01).

图7 凋落物分解速率和初始C:N的关系。加号表示凋落物的初始C:N。星号表示分解速率与初始C:N的相关性(**, p < 0.01)。

Fig. 7 Relationships between decomposition rate and initial C:N of all litters. Plus sign (+) represents initial C:N of litters. Asterisks denote significant differences between decomposition rate and initial C:N (**, p < 0.01).

图8 古尔班通古特沙漠的日最高气温和日最低气温的变化(2010年和2011年的3月15日-4月15日)。

Fig. 8 Variations of daily maximum air temperature and daily minimum air temperature in the Gurbantunggut Desert from March 15th to April 15th in 2010 and 2011.

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