Enzyme dynamics on decomposing leaf litter of Cistus incanus and Myrtus communis in a Mediterranean ecosystem
Enzyme dynamics on decomposing leaf litter of Cistus incanus and Myrtus communis in a Mediterranean ecosystem
复制标题
DOI：
10.1016/s0038-0717(00)00158-9
复制
发表时间：
2000-11-01
影响因子：
9.7
通讯作者：
Fuggi, A
中科院分区：
文献类型：
--
作者：
Fioretto, A;Papa, S;Fuggi, A
本文比较了夏季落叶种Cistus incanus凋落叶与常绿种Myrtus communis在地中海低矮灌木丛中15个月孵化过程中的分解情况。在随机选择的桃金娘属和桃金娘属灌木下分别放置垃圾袋。由于落叶灌木和常绿灌木的小气候条件不同，桃金娘灌木下也孵育了凋落物。通过测定凋落物呼吸和酶活性（纤维素酶、木聚糖酶、-淀粉酶、-淀粉酶、漆酶和过氧化物酶）来评价微生物活性。在孵化的前8个月，两窝凋落物的分解率与凋落物质量和孵化条件无关。凋落物的平均衰变常数(k)在0.29 +/- 0.03 ~ 0.33 +/- 0.03 yr（-1）之间，只有桃金娘属灌木下凋落物的衰变常数（k分别为0.57 +/- 0.15和0.48 +/- 0.16 yr(-1)）有所增加。干燥的夏季对桃金娘下孵化的凋落物的腐烂率有影响，而对桃金娘下孵化的凋落物没有影响。微生物呼吸呈季节性变化(25 ~ 150 μ mol CO2 g(-1) dry wt. 24 h(-1))，夏季较低，主要原因是凋落物含水量较低。样品放置在田间后，α -淀粉酶活性迅速下降，在山楂凋落物中降至零，而在桃金桃凋落物中仍可检测到α -淀粉酶活性(>0.02 μ mol葡萄糖g（-1) dry wt. h(-1)）。-淀粉酶活性在整个过程中都很低。纤维素酶和木聚糖酶的活性为1 ~ 30 μ mol葡萄糖当量（还原糖）g（-1）干wt. h（-1）。两个凋落物酶活性均在夏季最低，凋落物呼吸也在夏季最低。桃金鼠凋落物过氧化物酶活性（0 ~ 50 μ mol o-甲苯胺氧化g（-1）干wt. h(-1)）与纤维素酶和木聚糖酶具有相似的季节规律。在西斯都是检测不到的。在8 - 9个月间，两种凋落物的漆酶都显著增加，从10 μ mol o-甲苯胺氧化g（-1）干wt. h（-1）增加到140 μ mol o-甲苯胺氧化g（-1）干wt. h(-1)，真菌生物量也大幅增加（从0.5 mg g（-1）干wt.）。这些酶的分析结果显示，不同凋落物类型和小气候条件下，这些酶的质量和数量存在差异，表明微生物演替发生了变化。(C) 2000 Elsevier Science Ltd.版权所有。
The decomposition of Cistus incanus leaf litter, a summer deciduous species, was compared to that of Myrtus communis, an evergreen species, during 15 months of incubation in a Mediterranean low shrubland. The litterbags were placed under randomly selected shrubs of Myrtus and Cistus, respectively. Owing to the different microclimatic conditions under deciduous and evergreen shrubs Cistus litter was also incubated under Myrtus shrubs. Microbial activity was evaluated by measuring litter respiration and enzyme activities (cellulase, xylanase, alpha -amylase, beta -amylase, laccase and peroxidase). During the first 8 months of incubation the decomposition rate of both litters was independent of litter quality and incubation conditions. The average decay constant (k) ranged between 0.29 +/- 0.03 and 0.33 +/- 0.03 yr(-1) Subsequently, it increased only for litters incubated under Myrtus shrubs (k = 0.57 +/- 0.15 and 0.48 +/- 0.16 yr(-1) for Cistus and Myrtus litters, respectively). The dry summer affected the decay rate of litters incubated under Myrtus but not under Cistus. Microbial respiration showed seasonal changes (from 25 to 150 mu mol CO2 g(-1) dry wt. 24 h(-1)), with low levels in summer, mainly because of the low litter water content. After samples were placed in the field, alpha -amylase activity decreased rapidly, dropping to zero in Cistus litter, whereas it remained detectable in Myrtus litter (>0.02 mu mol glucose g(-1) dry wt. h(-1)). The beta -amylase activity was low over the entire period. The activities of cellulase and xylanase ranged from 1 to 30 mu mol glucose equivalents (reducing sugar)g(-1) dry wt. h(-1). Both litters showed the lowest enzyme activities in summer, when litter respiration was also at the lowest level. Peroxidase activity was detected in the litter of Myrtus(from 0 to 50 mu mol o-tolidine oxidised g(-1) dry wt. h(-1)) and had a seasonal pattern similar to cellulase and xylanase. It was undetectable in Cistus. In both litters laccase increased significantly going from 10 to 140 mu mol o-tolidine oxidised g(-1) dry wt. h(-1) between eight and nine months when a large increase of fungal biomass occurred (from 0.5 to 2.5 mg g(-1) dry wt.). The analyses of these enzymes have shown qualitative and quantitative differences depending on the litter type and the microclimatic conditions, suggesting changes in the microbial succession. (C) 2000 Elsevier Science Ltd. All rights reserved.