西双版纳热带雨林凋落叶分解的生态过程.Ⅲ.酶活性动态

doi:10.3773/j.issn.1005-264x.2008.03.011

摘要/Abstract

摘要：

该文通过野外试验和室内模拟相结合,系统研究了西双版纳热带雨林生态系统混合凋落叶分解过程中的酶活性动态。野外试验采用网袋法(1 mm和100 μm网眼)限制土壤动物的出入,室内模拟试验采用灭菌-接种法控制生物组成,从而研究不同生物组成或食物链结构条件下,凋落叶分解过程中的酶活性变化,以及酶活性与分解进程之间的动态响应。研究结果表明,转化酶和淀粉酶在有机残体的最初分解阶段发挥重要作用,参与易分解成分的转化和分解,这些酶与凋落叶分解进程之间存在显著的负相关性,且参与分解的生物组成越简单(缩短食物链),这些酶活性越高,是微生物在分解初期对底物加以利用的关键酶类;C _x酶、β-葡萄糖苷酶、木聚糖酶活性均在分解中期达到高峰,多酚氧化酶在分解后期迅速上升,对凋落叶中、后期木质素的分解起到关键性的作用,这些酶与凋落叶分解进程之间存在显著的正相关性,且参与分解的生物组成越复杂(延长食物链),这些酶活性越高,是微生物在分解后期对底物进一步利用的关键酶类;与C循环有关的酶类都可以作为有机物质分解进程的重要指标,与分解进程之间存在一定的动态响应,有机残体的分解过程实质上是一个酶解过程。

关键词: 西双版纳, 热带雨林, 凋落叶, 分解, 酶活性

Abstract:

Aims We tested the dynamics of nine enzymes during leaf litter decomposition in Xishuangbanna tropical rainforest both in the field and laboratory to explore the response of enzyme dynamics to decomposition under different food-web structures.

Methods We used coarse and fine (1 mm and 100 μm mesh size, respectively) litterbags in the field to create different food-web structures during litter decomposition. Most soil macrofauna such as nematodes could access only the coarse mesh litterbags, leaving only microbiota such as mites in the fine mesh litterbags. In the laboratory, sterilization and inoculation were adopted to investigate different enzyme dynamics with nematodes or only microbiota participating in litter decomposition.

Important findings Invertase and amylase increased more for shorter food webs at early stages of decomposition, while activities of endocellulase, β-glucosidase, xylanase and polyphenoloxydase increased to their maxima at later stages, but greater increase occurred with extended food webs. Invertase and amylase had negative and endocellulase, β-glucosidase, xylanase and polyphenoloxydase had positive relationships with litter decomposition (mass loss). Activities of enzymes responded to the process of litter decomposition. Invertase and amylase played key roles for microbiota utilizing the substrates at early stages of decomposition, while endocellulase, β-glucosidase, xylanase and polyphenoloxydase worked on the further decay of recalcitrant compounds at later stages. All enzymes related to C decay acted as effective indicators of litter decomposition. The decomposition of plant organic matter was essentially an enzymatic process.

Key words: Xishuangbanna, tropical rainforest, leaf litter, decomposition, enzyme activity

张瑞清, 孙振钧, 王冲, 袁堂玉. 西双版纳热带雨林凋落叶分解的生态过程.Ⅲ.酶活性动态. 植物生态学报, 2008, 32(3): 622-631. DOI: 10.3773/j.issn.1005-264x.2008.03.011

ZHANG Rui-Qing, SUN Zhen-Jun, WANG Chong, YUAN Tang-Yu. ECOLOGICAL PROCESS OF LEAF LITTER DECOMPOSITION IN TROPICAL RAINFOREST IN XISHUANGBANNA, SW CHINA. Ⅲ. ENZYME DYNAMICS. Chinese Journal of Plant Ecology, 2008, 32(3): 622-631. DOI: 10.3773/j.issn.1005-264x.2008.03.011

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链接本文: https://www.plant-ecology.com/CN/10.3773/j.issn.1005-264x.2008.03.011

https://www.plant-ecology.com/CN/Y2008/V32/I3/622

图/表 10

表1 试验年度(2004年4月~2005年3月)研究地区月平均气温和降雨量

Table 1 Average monthly temperature and amount of monthly precipitation at sampling time (2004.4-2005.3) in study site of Xishuangbanna

项目 Item	2004年																	2005年
项目 Item	4月 Apr.	5月 May		6月 Jun.		7月 July	8月 Aug.		9月 Sept.		10月 Oct.		11月 Nov.	12月 Dec.				1月 Jan.	2月 Feb.	3月 Mar.
气温 Temperature (℃)	21.5		23.6		24.7			25.5		25.2		25.4			24.2	22.3	19.8	15.0	16.8	19.3
降雨量 Precipitation (mm)	263.0		779.0		223.9			79.9		169.0		204.6			160.1	56.8	45.8	0.0	1.5	0.0

表2 研究样地土壤(0~2.5 cm)土层基本理化性质(平均值±标准误差)

Table 2 Physio-chemical properties of the top soil (0-2.5 cm) in experiment fields in Xishuangbanna (Mean±SE, n=14)

有机质Organic matter (g·kg^-1)	全氮Total nitrogen (g·kg^-1)	C/N	pH	容重Density (×10⁹mg·m^-3)
48.3±0.8	2.3±0.0	12.3±1.2	4.75±0.22	1.02±0.10

表3 试验用材料(混合凋落叶)基本理化性质(平均值±标准误差)

Table 3 Basic properties of materials (mixed leaf litters) used in the study (Mean±SE, n=3)

全碳 C (%)	全氮 N (%)	碳氮比 C/N ratio	灰分 Ash (%)	纤维素 Cellulose (%)	木质素 Lignin (%)
49.1±0.22	1.11±0.01	44.3±0.16	7.41±0.02	41.29±0.06	28.26±0.04

图1 植物样品粗酶液提取的一般流程主要参考Criquet等(1999)的研究方法,并做了部分修改 Enzyme extraction method mainly refered to Criquet et al. (1999) with some modifications a: 酶提取剂:110.99 g无水CaCl2、0.5 ml土温80,加水定容至1 L Extraction solvent was made in addition of CaCl2 110.99 g·L-1 and Tween 80 0.5 ml·L-1 b: PVPP:交联聚乙烯基吡咯烷酮,除色剂,使用前预先加10%HCl煮沸10 min,然后用NaOH中和,加蒸馏水洗至中性,将上浮多余水分倒出,使用时稍稍搅动 Polyvinylpolypyrrolidone, used as decoloring agent c: PEG:聚乙二醇,分子量15~20 kD,浓缩剂 Polyethylene glycol, molecular mass 15-20 kD, used to concentrate the dialyzed extract

Fig.1 Flow chart for enzyme extraction from plant materials

图2 不同处理转化酶活性动态平均值±标准偏差 Mean±SD (n=4 for field and n=3 for inoculated study) C: 大网眼网袋 Coarse mesh F: 小网眼网袋 Fine mesh M: 接种微生物 Incubated microbiota only MN: 接种微生物+线虫 Incubated microbiota and nematodes

Fig.2 Invertase activity during decomposition of leaf litters

图3 不同处理淀粉酶活性动态平均值±标准偏差 Mean±SD (n=4 for field and n=3 for inoculated study) 图例同图2 Legends see Fig.2

Fig.3 Amylase activity during decomposition of leaf litters

图4 室内外试验不同处理酸/碱性磷酸酶活性动态图例同图2

Fig.4 Acid and alkaline phosphatase activities during decomposition of leaf litters in field (n=4) and simulated (n=3) study Legends see Fig.2

图5 野外试验不同处理Cx酶、C1酶、β-葡萄糖苷酶、木聚糖酶、多酚氧化酶活性动态平均值±标准偏差 Mean±SD (n=4) 图例同图2

Fig.5 Dynamics of β-1,4-endoglucanase, β-1,4-exoglucanase, β-1,4-glucosidase, xylanase and phenol oxidase activity during litter decomposition in field study Legends see Fig.2

图6 室内试验不同处理Cx酶、C1酶、β-葡萄糖苷酶、木聚糖酶、多酚氧化酶活性动态平均值±标准偏差 Mean±SD (n=4) 图例同图2

Fig.6 Dynamics of β-1,4-endoglucanase, β-1,4-exoglucanase, β-1,4-glucosidase, xylanase and phenol oxidase activity during materials decomposition in simulated study Legends see Fig.2

表4 酶活性与分解失重率之间的相关性

Table 4 Correlation coefficients (r) for enzyme activities and mass loss rates of decomposing materials

酶种类 Enzyme type	处理 Treatment	失重率 Mass loss (%)
转化酶 Invertase	C	-0.331
	F	-0.713^**
	MN	-0.493^*
	M	-0.745^**
淀粉酶 Amylase	C	-0.373
	F	-0.561^*
	MN	-0.637^**
	M	-0.059
酸性磷酸酶 Acid phosphatase	C	-0.832^**
	F	-0.660^**
	MN	0.799^**
	M	0.827^**
碱性磷酸酶 Alkaline phosphatase	C	-0.203
	F	0.096
	MN	0.902^**
	M	0.246
C₁酶 Exoglucanase	C	-0.934^**
	F	-0.904^**
	MN	-0.894^**
	M	-0.946^**
C_x酶 Endoglucanase	C	0.587^*
	F	0.667^**
	MN	0.777^**
	M	0.280
β-葡萄糖苷酶 β-Glucosidase	C	0.746^**
	F	0.912^**
	MN	0.581^*
	M	0.280
木聚糖酶 Xylanase	C	0.573^*
	F	0.643^**
	MN	-0.198
	M	0.293
多酚氧化酶 Phenol oxidase	C	0.431
	F	0.335
	MN	0.580^*
	M	-0.236

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