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森林凋落物作为森林生态系统中一个特殊的结构层次,作为森林植被对降雨再分配的第二个作用层[1],具有较土壤更多更大的孔隙,能够截持降水,保持水分,抑制地表水汽蒸发,促进水分下渗作用,减轻或者防止旱灾[2-3]。不同植被群落其凋落物组成差异较大,可能具有不同的水文效应[4]。雷竹(Phyllostachys praecox)作为都江堰地区大面积引种的竹类,对当地农村经济带来了巨大的促进作用[5],而大面积的雷竹种植是否会对当地的生态产生负面作用?这是目前急需解决和研究的问题,目前对雷竹的研究主要集中在雷竹的栽培技术[6]、退化特征及土壤等方面[7],而对雷竹林下凋落物持水性的研究还鲜有报道。本研究以都江堰浦阳镇大面积发展的雷竹、慈竹(Neosinocalamus affinis)两种重要的人工竹林为研究对象,采用室内浸水法对其进行凋落物持水性研究,旨在为人工竹林可持续发展提供基础数据。
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试验地位于成都市都江堰市蒲阳镇,属四川盆地亚热带湿润气候,四季分明, 属于浅切割低山地貌类型。年均温度15.2 ℃,极端最低、最高温度分别为38 ℃~10 ℃,降雨量为1 243.8 mm,年平均相对湿度为81%,年平均日照时数为1 024.2 h,无霜期可达到269 d。雷竹林种植于2008年“5·12”汶川地震后,是在农用地上人工更新形成的(见表1)。
种名(灌木层) 种名(灌木层) 艾蒿
Artemisia argyi Levl. Et Vant.水芹
Oenanthe javanica(Bl.) DC铜钱草
Salvia substolonifera Stib.透茎冷水花
Pilea pumila (L.) A. Gray北马兜铃
Aristolochia contorta Bunge无心菜
Arenaria serpyllifolia Linn .糯米团
Gonostegia hirta (Bl.) Miq.蛇莓
Duchesnea indic (Andr) Focke马齿苋
Portulaca oleracea Linn.鳞毛蕨
Dryopteris sp.虎杖
Reynoutria japonica Houtt.狗牙根C
ynodon dactylon (Linn.) Pers.马唐
Digitaria sanguinalis (Linn.) Scop.饭包草
Commelina bengalensis Linn.威灵仙
Clematis chinensis Osbeck灯笼草
Physalis peruviana Linn.葎草
Humulus scandens (Lour.) Merr.鹅儿肠
Myosoton aquaticum (Linn.) Moench凹头苋
Amaranthus lividus Linn.漆姑草
Sagina japonica (Sw.) Ohwi空心莲子草
Alternanthera philoxeroides
(Mart.) Griseb珠芽艾麻
Laportea bulbifera
(Sieb.et Zucc) WeddTable 1. Tab. 1 Composition of herbaceous species under Phyllostachys praecox plantation
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采用室内浸泡研究凋落物的最大持水量和最大持水速率,以浸泡24 h后的持水量为最大持水量[4]。慈竹与雷竹凋落物层的最大持水量和最大持水速率见表2。4种凋落物层中:持水量以雷竹分解层为最大,为6970.35 g·kg–1,是其烘干质量的697.03%,慈竹分解层次之,为5720.91 g·kg–1,是其烘干质量的572.09%,慈竹未分解层第三,为5 455.76 g·kg–1,是其烘干质量的545.58%,雷竹未分解层最低,为4281.82 g·kg–1,是其烘干质量的428.18%。其中,雷竹分解层的最大持水速率最高,为900.07%,慈竹分解层次之,为715.99%,慈竹未分解层第三,为701.99%,雷竹未分解层最低,为510.00%。不同竹林类凋落物的分解程度不同,其持水过程与持水量也不同,但总的表现出分解层的持水量和持水速率高于未分解层[8]。
林型 最大持水量/(g·kg−1) 最大持水速率/% 慈竹(未分解) 5455.76±115.57 701.99±11.56 慈竹(分解层) 5720.91±300.44 715.99±30.05 雷竹(未分解层) 4281.82±199.33 510.00±19.93 雷竹(分解层) 6970.35±150.54 900.07±15.05 注:表中数据均为平均值±标准误 Table 2. Maximum water holding capacity and maximum water absorption rate of Phyllostachys praecox and Neosino calamus affinis litter
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4种凋落物的吸水速率从0.5~4 h吸水速率下降最快,4 h后逐渐下降并趋于平稳(见图1)。凋落物未分解层的吸水速率以慈竹最高,从浸泡0.5~24 h后,吸水速率由9679.98 g·kg−1·h−1)下降到227.32 g·kg−1·h−1,雷竹未分解层则从7464.16 g/kg·h下降为178.41 g·kg−1·h−1。凋落物分解层的吸水速率则以雷竹分解层最高,从浸泡0.5h~24 h后,吸水速率由10980.26 g·kg−1·h−1下降为290.43 g·kg−1·h−1,慈竹分解层次之,从11372.6 g·kg−1·h−1下降为238.37 g·kg−1·h−1。可见,慈竹分解层的吸水速率在0.5 h~1 h区间下降最为急剧,慈竹分解层、雷竹未分解层、雷竹分解层在0.5 h~4 h区间下降最快,6 h~24 h区间吸水速率则开始逐渐趋于平稳。通过单因素ANOVA分析LSD方程方差分析得出,慈竹(未分解层)与慈竹(分解层)间持水量与持水速率未达到显著相关(P>0.05),其余分解层间均差异显著。
由表2可见,各分解层吸水速率与浸泡时间拟合较好。除慈竹未分解层和雷竹分解层拟合系数R2小于0.9外,其余两者均大于0.9以上。
凋落物 方程 R 慈竹 未分解层 V=12831 t ~1.6641 R2=0.8572 分解层 V=14225 t ~1.6970 R2=0.9048 雷竹 未分解层 V=9087.2 t ~1.6842 R2=0.9361 分解层 V=15194 t ~1.5754 R2=0.8037 Table 3. Relationship between water absorption rate and time of artificial bamboo plantation litter
Comparative Study on Water Holding Capacity of Phyllostachys praecox and Neosinocalamus affinis Litter
doi: 10.12172/202104220001
- Received Date: 2021-04-22
- Available Online: 2021-10-22
- Publish Date: 2021-12-10
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Key words:
- Phyllostachys praecox /
- Neosinocalamus affinis /
- Litter /
- Water holding capacity
Abstract: To investigate the water holding capacities of Phyllostachys praecox litter, the water holding characteristics of litter (undecomposed layer and decomposed layer) under two main bamboo plantations were studied by indoor soaking method. The results showed that the maximum water holding capacity, maximum moisture rate and maximum water absorption rate of Neosinocalamus affinis undecomposed layer were 5455.76 g·kg−1, 701.99% and 9679.98 g·kg−1, respectively. Those of Neosinocalamus affinis decomposition layer were 5720.91 g·kg−1, 715.99% and 11372.6 g·kg−1, respectively. Those of Phyllostachys praecox undecomposed layer were 4281.82 g·kg−1, 510.00% and 7464.16 g·kg−1, respectively. Those of Phyllostachys praecox decomposition layer were 6970.35 g·kg−1, 900.07% and 10980.26 g/kg, respectively. The analysis showed that the maximum water holding capacity, maximum moisture rate and maximum water absorption rate of Phyllostachys praecox decomposition layer > those of Neosinocalamus affinis decomposition layer > those of Neosinocalamus affinis undecomposed layer > those of Phyllostachys praecox undecomposed layer. It could be concluded that litter decomposition layer whichwas decomposed by soil animals, soil microbe, and other decomposers had stronger water holding capacity and water absorption rate than undecomposed layer. The litter layer under bamboo plantation was an important structure layer for water holding, water conservation, overland flow retardation and preventing soil erosion. After decomposition, the litter of Phyllostachys praecoxhad better hydrological effect than that of Neosinocalamus affinis litter.