吉林蛟河不同演替阶段针阔混交林凋落物持水特性研究

凋落物层是森林土壤不可缺少的保护层,在森林水土保持及水源涵养中起着不可替代的作用。为探究中国东北东部山地不同演替阶段针阔混交林凋落物持水特性的变化规律,以及持水特性与演替阶段之间的关系,以吉林省蛟河市林业实验区管理局林场不同演替阶段针阔混交林凋落物为研究对象,分别在中龄林、近熟林和成熟林固定监测样地中采用蛇形取样法均匀地选择5个边长为20 cm的正方形样方,并将每个样方内的未分解层和半分解层的凋落物取回实验室进行持水特性分析。采用室内浸水法计算凋落物的蓄积量、持水量、持水率以及凋落物的有效拦蓄量,并结合野外观测数据分析林下凋落物的持水特性与演替阶段之间的关系。结果表明:不同演替阶段凋落物的总蓄积量为成熟林(7.26 t/hm~2)近熟林(4.56 t/hm~2)中龄林(3.68 t/hm~2),持水量大小为成熟林(21.23 t/hm~2)近熟林(35.24 t/hm~2)中龄林(47.71 t/hm~2),持水率大小为成熟林(844.72%)近熟林(742.58%)中龄林(592.02%),有效拦蓄量为成熟林(31.32 t/hm~2)近熟林(20.52 t/hm~2)中龄林(11.98 t/hm~2)。林分各演替阶段不同分解程度的凋落物持水量与持水率均随着浸水时间的增加呈对数关系增长,吸水速率则随浸水时间的增加呈幂指数关系下降。研究表明,成熟林的持水性能最强,近熟林、中龄林持水性能依次减弱。不同演替阶段林分最大持水量、最大持水率与蓄积量大小排序一致,表明持水量、持水率与蓄积量有很强的相关关系,蓄积量越大,凋落物持水量、持水率越高,森林凋落物持水能力越强。

Hydrological characteristics of forest litters in conifer and broad-leaved mixed forests at different forest successional stages in Jiaohe,Jilin Province

The forest litter layer is indispensible for the protection of forest soil, it plays an important role in forest soil and water conservation. The purpose of this paper is to analyze the variation laws of hydrological characteristics of forest litters in conifer and broad?leaved mixed forests at different successional stages in the northeast mountainous area of Chi?na. We investigated the forest litters in conifer and broad?leaved mixed forests at different successional stages in Jiaohe management bureau of forestry experimental area, Jilin Province. The litter samples were collected from middle?aged for?est, near?mature forest and mature forest. Within each forest plot, a total of five square subplots with dimension of 20 cm×20 cm were set up using serpentine sampling method. The litters in the un?decomposed layer and semi?decom?posed layer were taken back to lab for analyzing the hydrological characteristics of forest litters. The standard branch soa?king method was used to calculate the storage of forest litters, water holding capacity, water holding rate, as well as the modified interception amount. For each sample, the litters were divided into four groups evenly and part of the litters was selected to measure the weight by electronic analytical balance, and then put in the 100-mesh nylon mesh. The soaking time was set as 0.25, 0.5, 1, 2, 4, 8 and 24 h, respectively. Combined with the field observation data, the relationship between the hydrological characteristics of forest litters and successional stages was analyzed. The litter storage of mature forest was the largest ( 7. 26 t/hm2 ) , followed by near?mature forest ( 4. 56 t/hm2 ) , and middle age forest ( 3?68 t/hm2).The order of the maximum water holding capacity was as follows:mature forest (21.23 t/hm2)>near?mature for?est(35.24 t/hm2)>middle?aged forest(47.71 t/hm2)and the maximum water holding rate was 844.72% in mature forest, 742.58% in near?mature forest, and 592. 02% in middle?aged forest, respectively. The descending order of the modified interception amount was mature forest (31.32 t/hm2), near?mature forest (20.52 t/hm2), and middle?aged forest (11?98 t/hm2). The soaking experiment demonstrated that both water holding capacity and water holding rate had remarkable logarithmic correlation with soaking time, while the absorption rate and soaking time was of a power function. The water holding capacity of mature forest was the largest, followed by near?mature forest and middle age forest. This is due to the fact that along with the forest succession the forest crown tends to close, the understory species becomes rich and nutrients increase, therefore the water holding capacity of forest litter layers increase gradually. The orders of maxi?mum water holding capacity, maximum water holding rate and litter storage volume were consistent among different forest successional stages, which indicated that the there were strong correlation between water holding capacity and water holding rate with litter storage volume. The higher the litter storage volume, the higher the water holding capacity and water holding rate.