短枝木麻黄凋落小枝分解与单宁和养分含量的关系模型

Decomposition of Casuarina equisetifolia branchlets and relationship models with tannin and nutrient concentrations

采用数学模型拟合了短枝木麻黄小枝分解失重率与各基质质量(尤其是单宁)之间的关系,得到最优回归模型,并分析了单宁与养分含量之间的相关关系。正常林和衰败林凋落小枝分解的半衰期分别为0.78和0.71 a,分解95%的时间分别为3.36和3.05 a。采用修正的Olson指数衰减模型对正常林和衰败林中凋落小枝分解残留率和时间进行模拟,正常林和衰败林中凋落小枝的Olson指数衰减模型R2分别为0.969和0.984,均达到显著水平(P<0.01),说明该模型能较好地预测凋落小枝的分解动态。通过探讨短枝木麻黄凋落小枝分解失重率与各基质质量之间的关系,建立了失重率与单宁和养分之间关系的最优回归模型(正常林:y=-45.949 3-1.457 4x1+0.194 0x3+1.244 8x4+0.660 9x5,P<0.001;衰败林:y=15.144 1-1.555 1x1-27.237 2x2+0.185 8x3+0.576 1x5+0.516 9x7,P<0.001)。对凋落小枝分解过程中单宁和养分之间关系的相关分析表明,在正常林中,P含量与总酚(TP)含量以及N含量与蛋白质结合缩合单宁(PBCT)含量之间具有显著负相关关系,而衰败林中C∶N与TP含量具有显著正相关关系。

The lost weight rates of litters and various substrate contents （ especially tannins ） of Casuarina equisetifolia were studied , fitted those utilizing mathematic models and got the optimum regression model for the first time .The relationship between tannins and nutrient concentration during decomposition was also analyzed .Decomposition studies using litter bags suggested that the time required for the loss of half of the initial dry weight （t50）in normal and decline forests were 0.78 and 0.71 a;and t 95were 3.36 and 3.05 a, respectively.The corrected models of exponential decay by Olson were used to imitate the time and retention rate of litters . In normal and decline forests R2 were 0.969 and 0.984, respectively, both were at significant levels , indicated the models could forecast the decomposition dynamic well .The lost weight rates of litters and various substrate contents of C.equisetifolia were discussed relatively to set up a mathematical model of the best regression equation （normal forest： y=-45.949 3-1.457 4x1 ＋0.194 0x3 ＋1.244 8x4 ＋0.660 9x5 , P＆lt;0.001;decline forest：y=15.144 1-1.555 1x 1-27.237 2x 2＋0.185 8x 3＋0.576 1x 5＋0.516 9x 7, P＆lt;0 .001）.Correlation analysis between tannins and nutrient contents during decomposing showed that there were significant correlations between P and total phenolic （TP） contents as well as N and protein-bound condensed tannins （PBCT） contents in normal forests , while in decline forests , C∶N ratio had a significant positive relationship with TP contents .