Analysis of Sediment Source of Watershed in Western Shanxi of the Loess Plateau

1 INTRODUCTIONThe Loess Plateau is the most drastic soil erosion regionin China, with the most severe water erosion. Thedistribution of types and intensity of erosion not onlyhave regional diversity but also have perpendicularvariation. In the small watershed, there are differencesin erosion characters among its upper, middle and lowerreaches. It is very significant for taking rationalmeasures of soil and water conservation and forpreventing soil and water loss to analyze the relationbe…     

Research and Conservation of Forest Genetic Resources in China

The present situation of forest tree genetic germplasm resources research and conservation in China is introduced which including the background, decision-making of conservation strategies and principles, the plan of area division and tree species classification, the sample strategy of germplasm conservation, the advances in conservation pattern and related technologies research, the achievements of germplasm conservation and utilization in China, and the problems to be solved. The recent achievements and data related are listed.     

Monitor Forest Fires with FY Serial Satellites

Remote sensing as the measure to monitor disasters has the advantage of temporal resolution and large scale. Since "5.6 catastrophe" in 1987, China began to monitor forest fires broadly. In the summer of 2002, many forest/grass fires occurred in the Daxing'anling Mountains, and the damage was very heavy. In the forest fires fighting, the meteorological satellites play an important role in monitoring the fires. Especially the FY serial meteorological satellites have the advantage of large scale monitoring and characteristics of being in time and exact, and get good results. Remote sensing techniques have been used in many aspects of forest/grass fires research, including burned area and fireline intensity evaluation, post fire environment monitoring etc.     

秦岭松栎林带生物量及其营养元素分布特征

秦岭脱齿栎林、油松林和华山林（包括０－６０cm土层）营养元素总贮量达２９．２５００－３９０．１７３９t.hm^-2，其大小为锐齿栎林＞华山松＞油松林，土壤中营养现贮量占系统总量的９３．１０％－９９．３９％，植被层和凋落物层仅占０．５７％－３．００％和０．１０％－１．９９％；３林分乔木层生物量、木材蓄积量和营养元素积累量平均值分别为１２０．４８３t.hm^-2,129.384m^3.hm^-2和１２２６．９kg.hm^-2，锐齿栎林＞油松林＞华山松林。３林分林下植被层生物量现存量和营养元素积累量平均值分别为１．５５３t.hm^-2和５３．１kg.hm^-2，锐齿栎林最大，华山松林最小。林下凋落物现存量和营养元素积量平均值分别为１７．４７５t.hm^-2和５０２．５kg.hm^-2，３林分凋落物现存量、营养元素含量及其积累量都存在明显的差异。锐齿栎林、油松林和华山松林营养元素年吸收量、归还量、存留量和平均归还率分别为３３．４、１４７．２和２６４．３，１９５．６、６６．９和８４．１，１３８．８、８０．４和１８０．２kg.hm^-2和０．５８５、０４５４和０．３１８，３林分各营养元素的年吸收量，归还量和存留量也存在一定的差异，锐齿栎林干和皮中Ｃa和Ｍg含量远远高于油松林和华山松林的，锐齿栎林多代连作势必导致营养元素的大量流失，特别是Ｃa和Ｍg，会破坏土壤原有离子动态平衡，引起林地土壤理化性质改变，林地生产潜力逐渐下降。     

抚宁县英武山封山育林调查初报

<正> 一、封山区概况 抚宁县英武山村、地处秦皇岛市北部石质低山丘陵地带。全村109户,486口人;有驴、骡80头,羊600只;农业用地55公顷,各种果树20,00O株。山林总面积207公顷,主要为油松、栎类(纯林或混交林)次生林。由于多年来人、畜破坏、连续干旱、松毛虫害等影响,林分蓄积量每年每亩增长不足0.1立方米,受害严重的林分,林相残破,林木稀疏,有的地段已退化为严重的荒山坡,水土流失严重。全村烧柴和饲料日益缺乏。     

热带木材的干燥

一、大气干燥气干的优点是不用昂贵的设备.缺点是干燥时间长;必须库存大量木材因而影响资金周转;需要花工经常搬动;容易遭受菌虫害;气干的木材往往不能达到利用时的干燥要求等。 (一)气干场地的条件最好选择矿质土,潮湿的土壤排水良好和靠近江河均有利于菌类繁殖.场地应当设在车间或工厂附近,与车间之间应设有通     

Study on Balance between Supply and Demand for Timber and Timber Products in China

INTRODUCTION Because China is deficient in forest resources, and the forest has the characteristics of low quality, uneven distribution, slow growth and severe situation of ecological environment, the ecology construction has become the first requirement in society and with the implementation of the “Natural Forest Conservation Program”, Chinese forestry is in the historic transition from timber production to ecological construction. Therefore, the timber production in China increases…     

美国枫香组织培养胚状体的发生

美国枫香(Liquidamber Styraciflua)最初在固体培养基上长出的愈伤组织,移置到液体培养基上悬浮培养时,分化出正常形和畸形两种不定胚;再转移到固体培养基上培养时,从畸形不定胚叶处分化出许多次生不定胚。鱼雷期胚可以发育成正常植株。在琼脂培养基上培养时,也观察到了胚状体的发生。     

美国梧桐树病虫害(上)

叶部害虫1、网蝽:美国梧桐网蝽(Corythucaciliata)遍及美国东部,是一种危险性害虫,因成虫体上覆有纱罗状或网状翅而得名。若虫黑色扁平,体多刺。成虫和若虫群聚叶片上并吸食为害。被害叶成白色或棕色,形似叶蝉及螨类为害所形成的斑点、点刻和褪色斑。严重受害的叶片成褐色并早落。该虫不长严重大爆发,但每年都有零星、少量的爆发。最严重的为害最易见于市区的遮阴树和观赏树。干旱的夏末损害最显著。成虫蛰伏于寄主及其附近的落叶,枯树皮或其它隐蔽的场所内越冬。春天活动并爬     

森林与环境

森林是加拿大最突出的风景。从大西洋到太平洋3,000哩广阔的土地上处处是森林。森林工业现在使用着多种多样的资源。每一年的造林面积是2.5百万亩。(1英亩=6.072市亩=0.447公顷—译者)森林不仅仅影响着环境的性质,并且有适合于各种用途的资源。