Protective effect of floor cover against soil erosion on steep slopes forested with <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> (hinoki) and other species

 We evaluated the protective effects of floor cover against soil erosion in three types of forest located on steep slopes under a humid climate: 22- and 34-year-old Chamaecyparis obtusa (hinoki), 34-year-old Cryptomeria japonica (sugi), and 62-year-old Pinus densiflora (red pine) stands. We measured sediment transport rates (sediment mass passing through one meter of contour width per millimeter of rainfall), using sediment traps, before and after removing floor cover. Raindrop splash erosion was dominant in the experimental stands. Floor cover percentage (FCP) during the preremoval stage varied from 50% to 100% among the four stands, and sediment transport rates ranged from 0.0079 to 1.7 g m⁻¹ mm⁻¹. The rates increased to 1.5–5.6 g m⁻¹ mm⁻¹ immediately after removing floor cover, and remained high throughout the experiment. The presence of physical cover near the ground has a crucial effect on sediment transport on forested slopes. The protective effect ratio (the ratio of the sediment transport rate in a control plot to that in the removal plot) in a young hinoki stand, in which the FCP decreased markedly, was 0.3 at most, which is close to the rate for bare ground. The protective effect ratio in the red pine stand was ≤0.003. We concluded that the protective effect of floor cover in undisturbed forests in Japan differs by over two orders of magnitude, based on comparisons with previous studies. Received: March 11, 2002 / Accepted: August 16, 2002 Present address: Department of Forest Site Environment, Forestry and Forest Products Research Institute, Ibaraki 305-8687 Japan Tel. +81-298-73-3211; Fax +81-298-74-3720 e-mail: miura@affrc.go.jp Present address: Department of Forest Site Environment, Forestry and Forest Products Research Institute, Ibaraki 305-8687 Japan Tel. +81-298-73-3211; Fax +81-298-74-3720 e-mail: miura@affrc.go.jp Acknowledgments This study was supported by the Research Council of the Ministry of Agriculture, Forestry, and Fisheries, of Japan. We thank H. Ujihara, S. Ujihara, and M. Ogasawara in Otoyo, Kochi, who provided the experimental stands used in this study. We also thank K. Hirai, S. Kuramoto, E. Kodani, and the rest of the staff at the Shikoku Research Center, Forestry and Forest Products Research Institute, for their help in conducting the experiments. Correspondence to:S. Miura     

人工降雨条件下毛竹林地表枯落物固土防蚀效应

对长江三角洲森林生态定位站北亚热带次生毛竹林枯落物水土保持功能进行了模拟研究。结果表明:(1)在室内人工模拟降雨条件下,坡度和雨强是影响坡面侵蚀的重要因素,随着坡度和雨强的增大,泥沙浓度也不同幅度的增大;(2)坡度为5°、10°、15°、20°、26.5°时,裸露坡面和覆盖凋落物的坡面比较,随着坡度增加,覆盖有枯落物的泥沙浓度增幅明显减小,且减少幅度为52.9%～87.1%;(3)在室内人工模拟降雨条件下,雨强为10～50mm/h时,有枯落物覆盖的土壤侵蚀量比裸露坡面分别减少35.58 g/m2、66.82 g/m2、130.32 g/m2、190.62 g/m2和256.16 g/m2。覆盖凋落物的坡面径流量增大幅度相比裸露坡面低25%左右。因此,毛竹林地枯落物可以减少水土流失,有较好的保水保土作用,对控制水土流失有显著效果。     

Vegetation succession process induced by reforestation in erosion areas

Reforestation is one of the most important and efficient measures of water and soil conservation. Based on field investigations in the Shangyang Soil Conservation and Reforestation Station in Huizhou, Guangdong Province, China, we studied the variation in vegetation development, vegetation succession processes and soil erosion. The regional vegetation consists mainly of monsoon evergreen broad-leaved forests (MEBF). The area was deforested and became a denuded hill area with extremely high soil erosion in the 1960s and 1970s. Then, the area was closed in order to allow recovery of the vegetation. Under natural conditions the vegetation development and succession processes were slow during which soil erosion and strong sunshine and evaporation slowed down the development of the vegetation. About 25 years later, the vegetation cover was still merely 35% or so. The dominant vegetation types were heliophilous herbage and shrubs which formed a poorly developed shrub-herbage community and erosion remained high. In contrast, reforestation with selected tree species dramatically speeded up the vegetation succession process. About 12 years after reforestation, vegetation cover of the Acacia auriculiformis plantations in the Shangyang Station was 90% and erosion was under control. After 23 years, understory vegetation, consisting of indigenous species, had developed in the plantations. The planted trees and naturally developing herbage, shrubs, bamboo, local trees and liana formed a complex vegetation community in three layers. It will take 60 years for the vegetation to succeed from bare land to a secondary growth forest under natural conditions. Reforestation may speed up the vegetation succession process. The time may be reduced to 20 years. Reforestation is the most effective measure of vegetation restoration and erosion control in this area. __________ Translated from Acta Ecologica Sinica, 2006, 26(8): 2558–2565 [译自: 生态学报]     

山地林道路面土壤侵蚀的研究

本文采用标桩法和侵蚀沟调查法,研究了山地林道路面土壤侵蚀的内在规律、建立了侵蚀量与时间、坡长和坡度三个因子的关系。     

Effect of clear-cutting on the understory vegetation,soil and diversity of litter beetles in scots pine-dominated forest

Currently, the aim of modern forest management is not only timber production but also the protection of biodiversity. The initial effects of clear-cut logging on forest understory vegetation, soil and the diversity of litter beetles have been studied. We examined unstudied effects of clear-cutting disturbance on understory vascular plant species abundance, forest soils, and understory vegetation nutrients as well as beetle diversity one year after clear-cutting. Substantial changes in the prominence values and above-ground mass of forest-related vascular plant and moss species were detected. Clear-cuttings resulted in fast appearance of new light-loving plant species. The significant decrease in understory plant biomass influenced the reduction of nutrient pools in clear-cut areas after one year. The clear-cut logging negatively influenced the richness of species and the number of individuals of stenobiontic forest-related beetles in the forest litter. However, forest clear-cuttings were beneficial for eurytopic and open land species.     

Experimental studies on rain splash erosion of forest soils after clearing in Okinawa using an artificial rainfall apparatus

The main island of Okinawa, in southwestern Japan, is characterized by a subtropical climate, coral reefs, and reddish soils, which contain Acrisols and Cambisols (FAO/UNESCO classifications). Recently, due to soil erosion on hilly lands, the coral reefs have been damaged by an inflow of reddish soil. Forest clearing is thought to one of the factors increasing rain splash erosion rates on hilly lands, because it is believed that clearing disturbs the forest floor and causes the supply of litter to stop. After clearing, A0, A and B horizons will be denuded, one after the other, by rain splash. In this study, we measured rain splash erosion rates of undisturbed samples of A0, A and B horizons using an artificial rainfall apparatus. The results of experiments on rain splash erosion clarified several aspects of the erosion process in a clearing site. First, it was found that the rain splash erosion rates were higher in fresh litter than in decomposed litter, in decomposed litter than in the A horizon, and in the A horizon than in the B horizon. Thus, the erosion rate increases with soil depth. Secondly, surface-gleyed red and yellow soils are mostly vulnerable to rain splash erosion. The erosion rates of these soils are two to three times higher than those of the red soil and the yellow soils. Thirdly, the erosion rates are affected mainly by bulk density and saturated hydraulic conductivity, not by clay ratio and dispersion ratio. Lastly, the difference between erosion rates of surface-gleyed red and yellow soils and other soils will be even greater if a soil crust has formed, because the formation of a soil crust increases the rain splash erosion rate.     

梁山慈竹在退耕还林中的水土保持效应研究

利用小型径流观测场对比观测降雨时间集中的梁山慈竹林和未退耕种植红薯的耕地的17次降雨、10次水土流失过程进行效益对比,分析侵蚀量、径流量与降雨因子的关系。结果表明,退耕还梁山慈竹林的穿透降水率为89.14%,茎流率平均为1.57%,林冠截持降水率为9.29%;凋落物层的最大持水量约为27.54 t.hm-2,相当于水深2.4～3.3 mm,占降水量的14.46%～19.88%;与未退耕地相比,梁山慈竹林的平均径流量比耕地减少24.6%,而耕地侵蚀量约是林地的4.7倍,林地降水的泥沙侵蚀平均减少量达到78.56%。梁山慈竹有较好的水土保持作用,能够明显地减少地表径流和泥沙侵蚀。     

长江上游部分地区土壤侵蚀与机制探讨

通过调查、定位与半定位观测,研究了长江上游不同地貌类型区的土壤侵蚀空间分布格局,以及各影响因子与土壤侵蚀间的关系。揭示了泥沙运行机制和水土流失规律,提出了小流域泥沙运移的输移比:流域面积小于5km~2,用0.6～0.7作为泥沙输移比;小于30km~2,用0.3～0.4作为输移比,推算流域土壤流失量,并建立了坡面和小流域土壤流失预报模型。     

TDS调节剂对板栗叶片光合强度及其产物输出的影响*

ＴＤＳ调节剂对板栗叶片光合强度及其产物输出的影响苏梦云，胡小明，吴祖洪，应廷龙，周国璋关键词ＴＤＳ调节剂，板栗，光合强度，光合产物输出ＴＤＳ调节剂处理对板栗（ＣａｓｔａｎｅａｍｏｌｌｉｓｓｉｍａＢｌ．）具有提高结果率和增加产量的作用［１，２］，但对其...     

集约经营人工林的环境保护效应研究

为了揭示造林工程对环境产生的影响,特别是高标准造林和幼林经营活动对造林地水土流失的影响,在安徽省"世界银行贷款国家造林项目"和"世界银行森林资源发展和保护项目"新造林地有代表性地区设置水土流失定位观测点、建立径流小区,进行连续水土流失定位观测,并查阅与借鉴国内外有关经营人工林的资料,系统探索、分析了集约经营人工林在环境保护方面的效应.     

不同地表覆盖物对南方红豆杉大田播种育苗效果的影响

采用完全随机区组设计,对3种覆盖条件（切碎稻草、新鲜苔藓和地膜）下,南方红豆杉大田播种育苗苗木的种子出苗率、苗木保存率、苗高生长及地径生长的情况进行了研究.结果表明：3种不同覆盖条件对种子出苗率、苗木保存率、苗高和地径的影响从优到劣的顺序均为苔藓覆盖＞地膜覆盖＞稻草覆盖.不同圃地覆盖物对苗木的苗高生长产生了极显著的影响.新鲜苔藓覆盖下苗高生长最大,达到26.1 cm;而切碎稻草覆盖下苗高生长最小,为18.4 cm.不同圃地覆盖物对苗木的地径生长产生了显著的影响.新鲜苔藓覆盖下地径生长最大,达0.55 cm;而切碎稻草覆盖下地径生长最小,仅达0.43 cm.综合分析可知,新鲜苔藓是南方红豆杉大田播种育苗的首选覆盖物.     

黄花倒水莲播种育苗的影响因子研究

为掌握黄花倒水莲播种育苗的最适条件,以黄花倒水莲当年采收的种子为研究对象,采用常规播种方式,研究播种密度、覆土基质及覆土厚度等因子对种子萌发及生长状况的影响,分析各处理对出苗率、苗高及基径等指标的影响。结果表明:在播种育苗的不同处理之间,黄花倒水莲的出苗率、苗高及基径的差异均达到显著水平。综合考虑各因素影响效果,采用播种密度为125~165粒·m-2、覆土基质为火烧土∶红心土=2∶1、覆土厚度为2.0~3.0cm为优,可以在一定程度上,提高单位面积内合格播种苗的质量与产量。     

Characteristics of runoff and sediment generation of forest vegetation on a hill slope by use of artificial rainfall apparatus

We studied the impact of forest vegetation on soil erosion,surface runoff, and sediment generation by using field simulated rainfall apparatus. We measured runoff and sediment generation of five 4.5 × 2.1m runoff plots (a bare soil as a control; two Pinus tabulaeformis forestplots and two Platycladus orientalis forest with row spacing of 1 m × 1m and 1.5 m × 1.5 m, respectively) in Beijing Jiu Feng National ForestPark under three rainfall intensities (0.42, 0.83, 1.26 mm per minute).Forest vegetation significantly reduced soil erosion and sediment yield.Mean total runoff volume in the four tree stand plots was 93% of that inthe control plot, demonstrating the limited effectiveness of forest vegetation in runoff control. With increasing rainfall intensity, runoff reductionin forest plots declined from 28.32% to 2.1%. Similar trends in runoff coefficient and the relationship between runoff volume and rainfall duration was observed. Mean total sediment yield and mean sediment yield reduction rate under different treatments was 55.05% and 43.17% of those in the bare soil control plot, respectively. Rainfall intensity playedan important role in runoff and sediment generation processes, and had agreater impact on runoff than on soil erosion and sediment generation.When considering several factors in runoff and sediment transport processes, the P. tabulae form plot with row spacing at 1 × 1 m had a greater effect on soil and water conservation than did other forested plots.     

仿真固沙灌木林与塑料网方格沙障防风固沙效能比较

干旱区的水资源限制了植物治沙应用范围,将仿真固沙灌木加入退化梭梭林,比较仿真固沙灌木＋梭梭的灌木林与塑料网方格沙障防风固沙效能,为仿真固沙灌木应用提供参考。在野外相同条件下观测比较仿真固沙灌木林与塑料网方格沙障内风速,结果显示：仿真固沙灌木＋梭梭灌木林的风速削减率与塑料网方格沙障的差异不显著;随着风速增大,仿真固沙灌木降低风速率与塑料网方格沙障降低风速率差异变小;在风速为8.1~8.9 m s-1时,仿真固沙灌木降低风速率达塑料方格沙障的80%;仿真固沙灌木＋梭梭灌木林的输沙率随高度变化为指数递减,是裸沙地的35%;仿真固沙灌木林的建立不受气候条件影响,可重复应用,与灌木搭配可增强防风固沙效能。     

模拟外源性氮磷对马占相思凋落叶分解及土壤生化特性的影响

[目的]研究外源性氮和磷对马占相思凋落叶的分解速率、分解过程中N、P、K含量和土壤生化特性的影响,以便为森林土壤养分管理提供参考。[方法]以广东省云勇林场马占相思林下凋落叶为试验材料,采用尼龙网袋分解法,设置对照(CK)、施N(10 g·m~(-2))、施P(5 g·m~(-2))、施N+P(N 10 g·m~(-2)+P 5 g·m~(-2))4种处理,每隔3个月取样1次,并测定凋落叶残留量和N、P、K含量。[结果]表明:施N、P和N+P处理对马占相思凋落叶的分解均为促进作用。各处理马占相思凋落叶的N含量在分解过程中大致保持稳定,施P和N+P处理的凋落叶P含量在分解过程中总体呈波动性上升,而各处理的凋落叶K含量变化规律不明显。施N、P和N+P处理提高了马占相思林土壤的有机质和全N含量,促进脲酶、磷酸酶及过氧化氢酶的活性。[结论]施N、P和N+P处理促进了马占相思凋落叶的分解,有利于马占相思林的养分循环。     

不同措施对提高沙地造林成活率的研究

采用固体水、保水剂和覆膜措施，对提高造林成活率进行了比较试验。结果表明，与对照相比，这些措施明显提高了土壤含水量，从而不同程度提高了沙区造林成活率。其中覆膜措施效果最佳，其次为保水剂，最后是固体水措施。