MONITORING GEOMORPHOLOGICAL DISTURBANCE AND RECOVERY IN COMMERCIALLY LOGGED TROPICAL FOREST, SABAH, EAST MALAYSIA, AND IMPLICATIONS FOR MANAGEMENT

Resource development in the form of cyclical commercial logging activities results in a short period of often severe land disturbance followed by a prolonged phase of recovery. The monitoring of catchment sediment yield gives some indication of the gross erosion processes within the catchment as a result of the disturbance and may also effectively measure any ameliorative processes. Studies in Ulu Segama, Sabah, East Malaysia, recorded significant increases in stream suspended sediment loads as a result of logging. Stream loads were derived from a combination of daily sample measurements and storm event sampling using automated liquid samplers. Measured loads were then compared to computed loads from sediment discharge rating sets derived from the actual samples. Application of these ratings in the disturbed catchment initially underestimated sediment loads; however, a progressive overestimation of loads occurred as the catchment vegetation recovered. When using sediment rating curves as a tool to measure catchment erosion rates in disturbed environments, considerable caution has to be used. Vegetation recovery is reflected in the rapid recovery of stream water quality, making it necessary to continually review the rating.     

黄土地区梁峁坡的坡地特征与土壤侵蚀

本文指出黄土地区梁峁坡的坡角主要分布在14°—28°之间,特征坡角的上限相当于黄土的内摩擦角,下限相当于内摩擦角的0.45倍。黄土地区的坡地形态可分为直形坡、凸形坡、凹形坡、复合形坡和阶梯形坡等五种类型。土壤侵蚀主要受坡地形态和坡度的控制,侵蚀量随着坡度的增大而增加,坡度大于15°时,侵蚀量突增,坡面冲刷加剧,26°达极大值,此后冲刷作用减弱,重力侵蚀逐渐显著,至45°侵蚀达到最大值,以后又趋减弱。     

西双版纳原始热带季节雨林净初级生产力

研究了西双版纳原始热带季节雨林生物量增量、凋落量、叶虫食量和净初级生产量.该雨林年平均净初级生产量为25.764 t/hm2.a,其中各层次的净初级生产量分别为:乔木层23.972 t/hm2.a(占总净初级生产量的93.04 %)、灌木层0.749 t/hm2.a (占2.91 %)、木质藤本层0.431 t/hm2.a(占1.67 %)、草本层0.612 t/hm2.a(占2.38 %).乔木层净初级生产量分配为:凋落量11.566 t/hm2.a、叶虫食量0.694 t/hm2.a和生物量增量11.712 t/hm2.a.     

黄土峁坡耕地土壤侵蚀与泥沙输移

运用２０世纪五六十年代大气核试验所产生的人工放射性同位素￣（１３７）Ｃｓ为示踪元素，分析了陕西省子长县黄土峁玻耕地￣（１３７）Ｃｓ的坡面分布特征，计算出该坡耕地土壤侵蚀模数６３８０—８８９０ｔ／［（ｋｍ）￣２·ａ］；坡地底部剖面６和剖面１４的土壤堆积速率分别为２８０和４２３０（ｔ／［（ｋｍ）￣２·ａ］；该坡地剖面线１和剖面线２方向上的泥沙输移比０．９６。     

基于物种喜光性划分的热带山地林植物功能群及变化规律

依据物种为对光照不同要求,划分海南岛热带林物种为不同喜光性的功能群,应用NMS、非参数单因素方差分析法(ANOVA)和多重比较法(Post Hoc Tests)等方法,分别研究各功能群与环境因子的关系,及其随热带林不同干扰类型和恢复时间的变化差异.结果表明:(1)海南岛热带山地雨林以耐阴性功能群组成为主,主要分布于沟谷和坡地老龄林中,与热带林的恢复时间、土壤石砾含量、pH、全P和速效K成正相关,与海拔高度和土壤有机质成负相关性.(2)喜光性功能群主要存在于次生林中,与干扰类型、土壤速效和全N成负相关性,与采伐强度成正相关性.(3)随着刀耕火种后山地雨林次生林的恢复时间增加,强耐阴性功能群的分布增加,而喜光性功能群的分布则减少.(4)随着人工采伐后山地雨林次生林的恢复时间增加,各功能群的分布变化不明显.     

SOIL,SUBSOIL, AND FOREST COMPOSITION IN SOUTH-CENTRAL MICHIGAN,USA

Although soil texture is an important predictor of upland forest composition in southern Michigan, the relationship in some areas is weak and other environmental factors may exert stronger control on species composition. One of these may be concealed subsoil lithology where coarse-textured glaciofluvial sediments are buried beneath finer-textured till. Samples of forest composition, soil, and subsoil characteristics from 48 less-disturbed woodlots in the south-central Lower Peninsula reveal that upland oaks and hickories are predominant where the till veneer is thin and sand and gravel are relatively near the surface. Where till is relatively thick and outwash is deeply buried, woodlot composition is sugar maple-beech. In each of these cases, soil texture is unrelated to stand composition. The likely effect of buried near-surface glaciofluvial sediments is moisture stress such that xeric species dominate these drier sites. The influence of subsoil on forest geography is a significant new finding with regard to southern Michigan and has possible application elsewhere in glaciated eastern North America.     

ODONATE COMMUNITIES （ODONATA： INSECTA） IN A TROPICAL RIVER BASIN, MALAYSIA

Odonata larvae were sampled from 16 tributaries of Kerian River in the Kerian River Basin (KRB) using a kick samphng technique from September 1998 to May 1999 encompassing both rainy and dry seasons. The distribution of odonate genera was significantly different ( F15.16 = 3.99) among rivers in both seasons ( F15.16 = 4.70) at P = 0.05. However, no seasonal influence was detected. Protoneuridae and Libellulidae were the most dominant families in this basin. Other families Gomphidae, Coenagrionidae, Macromiidae, Chlorocyphidae and Calopterygidae, were common but Aeshnidae and Eupheidae were rare. Several common species, Prodasineura autumnalis, Brachythemis contaminata, Macromia gerstaeckeri, Paragomphus, Orthetrum brunneum, Rhinocypha quadrimaculata and Copera marginipes were identified. The calculated values of biological indices ( H‘, D, E, R1 and R2) showed that the dragonfly fauna in this river basin was slightly poor. Varied physieo- chemical parameters of the river possibly as a result of human activities in surrounding areas were found to influence the distribution of the dragonfly larvae in the KRB. This study showed that the KRB provided favorable habitats for Protoneuridae and 1Libellulidae. Two most dominant species Prodasineura autumnalis and Brachythemis contaminata were obviously favoured slightly acidic water of the Kerian river tributaries.     

元谋干热河谷区水土流失现状及治理对策

元谋干热河谷区气候炎热干燥、植被稀疏、生态环境脆弱,加之人类活动的干扰,水土流失严重,流失面积1080.79km^2,占总面积的53．5％。通过对水土流失特征、危害、水土保持存在问题的分析,提出了该区水土流失的治理措施和建议。     

HUMAN IMPACT ON SOIL EROSION AND SEDIMENT YIELD IN NORTHERN SHAANXI, CHINA

ｏｒｔｈｅｒｎＳｈａａｎｘｉｉｓｏｎｅｏｆｔｈｅｒｅｇｉｏｎｓｅｘｐｅｒｉｅｎｃｉｎｇｍｏｓｔｓｅｒｉｏｕｓｓｏｉｌｅｒｏｓｉｏｎｉｎＣｈｉｎａ.Ｓｕｂｓｔａｎｔｉａｌｒｅｓｅａｒｃｈｅｓｉｎｄｉｃａｔｅｄｔｈａｔｉｎａｄｄｉｔｉｏｎｔｏｐｈｙｓｉｃａｌｆａｃｔｏｒｓｔｈａｔｐｌａｙａｄｅｃｉｓｉｖｅｒｏｌｅｉｎｉｎｄｕｃｉｎｇｓｏｉｌｅｒｏｓｉｏｎ,ｈｕｍａｎｆａｃｔｏｒｓｔｈａｔａｃｃｅｌｅｒａｔｅｅｒｏｓｉｏｎｐｒｏｃｅｓｓｃａｎｎｏｔｂｅｉｇｎｏｒｅｄｅｉｔｈｅｒ[1,2,4].ＮｏｒｔｈｅｒｎＳ…     

RUNOFF PRODUCTION AND EROSION PROCESSES ON A DEHESA IN WESTERN SPAIN*

ABSTRACT. Runoff generation and soil erosion were investigated at the Guadalperalón experimental watershed (western Spain), within the land‐use system known as dehesa, or open, managed evergreen forests. Season and type of surface were found to control runoff and soil‐loss rates. Five soil units were selected as representative of surface types found in the study area: hillslope grass, bottom grass, tree cover, sheep trails, and shrub cover. Measurements were made in various conditions with simulated rainfall to gain an idea of the annual variation in runoff and soil loss. Important seasonal differences were noted due to surface cover and moisture content of soil, but erosion rates were determined primarily by runoff. Surfaces covered with grass and shrubs always showed less erosion; surfaces covered with holm oaks showed higher runoff rates, due to the hydrophobic character of the soils. Concentrations of runoff sediment during the simulations confirmed that erosion rates at the study site depended directly on the sediment available on the soil surface.     

ADULT DRAGONFLY COMMUNITIES IN TROPICAL RIVERS OF THE NORTHERN PENINSULAR MALAYSIA： SPECIES COMPOSITION, BIOTOPE AND HOST PLANT PREFERRENCES

1INTRODUCTION Manyfactorshavebeenlinkedwithobserved patternsofodonatediversity.Eachhabitatisdifferent andpresentsitsownopportunitiesforexploitationby welladaptedspecies(Krebs,1989).Theyaresensi tiveresponderstonewlycreatedphysicalandtogether withphysiogra…     

皖西山区水土流失及其综合治理

皖西山区海拔均≥ 1 0 0 m,最高峰白马尖海拔 1 774m.区内曾水土流失严重 ,面积达 4931 km2 ,占全区面积的 60 % .1 983～ 1 994年经综合治理 (特别是小流域综合治理 )后 ,水土流失面积减少了 1 0 62 km2 ,得以初步控制     

PITCHER PLANTS RECORDED FROM BRIS FOREST IN JAMBU BONGKOK, KUALA TRENGGANU, MALAYSIA

1INTRODUCTION NepentheswhichareknownlocallyinPeninsular Malaysiaasperiukkerabelongtoamonogenericfami lyNepenthaceae.Atpresent,atotalofninespecies(excludingnaturalhybrids)arerecordedfromPenin sularMalaysia.Ofthese,fourspeciesareendemic,whilsttheotherfivespeciesarefoundoutsidethepen insula.Thespeciescanarbitrarilybeclassifiedinto thelowlandspeciesandthehighlandspecies(Clarke,2002;Shivas,1984;Kurata,1976).Threespeciesarefoundinthehighlandhabitatscom monlyatanelevationofabove1000mforaboves…     

热带北缘裸地与桉树林地降水-地表侵蚀特性的对比研究

本文研究了水滴动能与地表侵蚀的相互关系问题，通过对相邻的两个地类：没有任何植被的光裸地和地表同样光裸但有人工桉树林的２个试验小集水区的对比研究，说明了单位雨量下的侵蚀强度与水滴动能存在最为紧密的关系。裸地地表的侵蚀强度决定于大气降水动能，而桉树林地的侵蚀强度却主要与林冠的穿透水水滴动能成正相关。总的说来，桉树林林冠的存在加大了林地所接受的降水动能，特别是在中小降雨强度的情况下更是如此，这就说明了营造人工林时，必须考虑到林冠结构与林地地表冲蚀的问题     

论长江与珠江流域的水灾、水土流失及植被生态恢复工程

系统总结了长江和珠江流域近百年来的洪涝灾害和水土流失的危害程度和发生规律,深刻分析了洪灾和水土流失日趋严重的根源,提出了治理“两江”流域水土流失的根本性措施———植被生态工程,并呼吁将传统的植树造林改为植树种草,将乔、灌、草、藤有机搭配,形成多层配置,并大力发展草业,最终在“两江”流域实现以草业为枢纽的可持续发展生态大农业。     

九龙甸水源区桉树林与云南松土壤特性比较

通过参照本土云南松次生林土壤的性质,对外来的不同生长段桉树林土壤进行系统的物理性质分析,揭示桉树种植对土壤结构的改造过程。测定结果分析表明：相对于云南林次生林,不同生长段的桉树林土壤在容重、细颗粒含量上表现出较高值;而自然含水量、饱和含水量、总孔隙度、毛管孔隙度、有机质含量等值却很小。因此,桉树种植改变了本土植被下形成的土壤,导致土壤结构状况变差。