连栽措施对桉树人工林结构及持水性能的影响

Effects of continuous planting rotation on forest structural characteristics and water holding capacity of Eucalyptus plantations

以海南岛4代连栽桉树人工林为研究对象,对比分析了不同连栽措施间,桉树人工林的结构、组成及其林下凋落物和土壤持水性的变化规律,探讨了桉树连栽措施对林地生态系统结构和水文调节功能的影响。结果表明,在桉树林生长特征上,第4代比第1代桉树林在胸径、树高和生物量上分别降低了43.4%、33.7%和42.7%;在生物多样性方面,桉树林下植物种类的数量随着连栽代次增加而呈下降趋势(p<0.05);在凋落物持水性能上,第1代桉树林下凋落物蓄积量和最大持水量最大,要比第4代高30.0%以上,但是最大持水率在不同连栽代次间差异不显著(p>0.05);在土壤持水特征上,随连栽代次增加,桉树林下土壤容重提高,而孔隙度、渗透速率以及持水量明显降低,其中1代桉树和3、4代间存在显著差异(p<0.05)。连栽措施明显改变了桉树人工林群落结构特征及其持水功能。

Abstract： The four rotations eucalyptus plantations with continuous planting were chosen in Hainan Island and forest structure characteristics and water holding capacity of soil and litter were investigated to examining the influence of continuous planting rotations on forest structure and hydrological regulating functions. The results show that the diameter at breast height （DBH） , tree height and above ground tree biomass decreased with increasing continuous planting rotations and the declining trends of them stressed. The DBH, tree height and above ground tree biomass of the 4~ rotation eucalyptus plantations were 43.4% ,33.7% ~ 42.7% lower than them of the 1 s, rotation plantations respectively. For forest biodiversity, the grass species under eucalyptus plantations decreased with increasing continuous planting rotations （p 〈 0. 05 ）. For litterfall eco-hydrological roles, litter stock and maximum water holding capacity of the 1 s, rotations were higher above 30.0% than them of the 4＇h rotations. However, litter maximum water holding rate did not differed significantly among different continuous planting rotations （p 〉 0.05）. For soil eco-hydrology roles, soil bulk density increased and soil total porosity, final constant infiltration rate and water holding capacity obviously decreased as continuous planting rotations increased. There were significant differences in soil total porosity, infiltration rate and water holding capacity between the 1^st rotation and the 3^rd or 4^th rotation. Thus, the continuous planting rotations clearly affected forest structural characteristics and eco-hydrological roles of eucalyptus plantations. Finally, the continuous planting rotations resulted in ecosystem services degradation of artificial eucalyptus forest.