混交林的研究进展分析

从4个方面对混交林的研究概况进行论述和分析：混交林研究的历史;从生态学角度研究混交林中的种间关系;树种间相互作用的主要方式;树种间生理生态作用效果。     

Weed control and autumn-olive affect early growth and survival of black walnut in a hardwood clearcut

Eight years after planting in a hardwood clearcut, black walnut trees in plots with weed control had significantly better survival and were taller and larger in diameter than those in plots without weed control. Planting autumn-olive with walnut also significantly increased height and diameter of the walnuts but did not affect their survival.     

Agroforestry systems in the Garhwal Himalayas of India

Agroforestry systems, though at subsistence level are well established in Garhwal Himalayas. The farmers undertake cultivation of various crops, seasonal and biennials crops with trees all in mixtures on the same piece of land. Farm animals and poultry form an essential component of the systems. The intimate association of different species provides both subsistence and commercial products which give additional income to the farmer. The paper describes the general scenario of socio-economic condition and existing agroforestry practices and some suggestions for their improvement in the Garhwal Himalayas.     

黄土丘陵沟壑区混交林类型与模式

经过调查与研究表明：黄土丘陵沟壑区目前人工混交林有25种混交模式，4种混交类型，即针阔混交、针叶混交、阔叶混交以及乔灌混交等。各种混交林的生长发育、抗逆性及生态功能等均优于纯林。本文提出了各种混交林的混交方式、混交比例、营造方法等，可供有关方面造林绿化和退耕还林时参考。     

红锥不同模式造林效果分析

对红锥纯林、红锥×杉木混交林以及红锥×木荷×杉木混交林等不同模式造林试验研究结果表明 ,在 3种不同混交模式中 ,以红锥杉木混交效果最好 ,不但能明显地提高红锥的造林成活率 ,且两者混交种间关系较为协调 ,空间分布格局合理 ,充分利用营养空间 ,混交林分的产量和质量得到了明显的提高。 18年生红锥杉木混交林中红锥的平均树高、胸径、单株材积分别达 14 75m、16 5 0cm和 0 15 6 1m3 ,比红锥纯林分别提高了 10 0 0 %、14 34%、36 93% ,林分蓄积量高达 2 71 4 7m3·hm-2 ,是纯林的 1 30倍 ,可见红锥与杉木混交是值得闽南地区推广应用的针阔混交模式     

Insect natural enemies of <Emphasis Type="Italic">Ips typographus</Emphasis> (L.) (Coleoptera,Scolytinae) in managed and unmanaged stands of mixed lowland forest in Poland

We tested the effects of forest management type (managed vs. unmanaged) on the abundances of Ips typographus (L.) (Col., Curculionidae, Scolytinae) and related parasitoids and predators reared from spruce bolts exposed in Białowieża, Poland. Habitat availability for these species differed between forest types mainly as a result of regular sanitary fellings occurring in managed forests. Populations of the common polyphagous insect predators Paromalus paralellepipedus (Herbst) and Plegaderus vulneratus (Panz.) (Col., Histeridae) or parasitoids Rhopalicus tutela (Walk.), Dinotiscus eupterus (Walk.) and Roptrocerus xylophagorum Ratz. (Hym., Pteromalidae) related to I. typographus did not differ between managed and unmanaged forests. Only Thanasimus spp. (Col., Cleridae) was significantly more abundant in managed forest, possibly because it was favored by the more open, sunny stands. However, the experiment was performed in stands where spruce is only a minor component and during the non-epidemic phase of the bark beetle population, so further experiments may be necessary to determine if the effects of sanitary fellings are greater in different forest types and at different stages of the population cycle.     

杉木马褂木不同混交比例土壤团粒结构的分形特征研究

应用分形理论、弹性分析及边际分析法,建立了土壤团粒结构的分形维数与土壤团聚体含量、土壤结构体破坏率之间的回归模型,研究不同杉木、马褂木造林模式的土壤团粒结构分形维数对林地土壤结构性质变化影响的效应。结果表明:土壤>0.25 mm的团聚体及水稳性团聚体含量越大,团粒结构的分形维数越小,土壤结构越好,在不同杉木、马褂木造林模式中,以杉木和马褂木混交比例(3∶1)的土壤结构性最好;土壤团粒结构的分形维数与土壤团聚体、水稳性团聚体之间存在显著回归关系。土壤团粒结构分形维数对土体性质的变化产生较大的效应,为林地土壤科学管理提供了理论依据。     

广西三门江国家森林公园林相改造初探

在分析广西三门江国家森林公园林相改造现状的基础上,提出公园林相改造的重点是对针叶纯林的改造。即对针叶林进行大强度疏伐,然后进行混交造林。选择乡土树种是混交造林的关键。     

建水石质山地两种乔灌混交模式的造林成效

在建水县石质山地进行了墨西哥柏 车桑子混交模式和干香柏 车桑子混交模式的造林试验。6年的试验结果表明:两种乔灌混交模式的造林成活率、保存率均较高,林木的生长状况也较好。前者中墨西哥柏的造林成活率和保存率均为100%,车桑子均为94.44%;后者中干香柏的造林成活率为77.78%、保存率为72.22%,车桑子均为100%。经用层次分析法对两种混交模式的乔灌木层次的明显性、群落的盖度、林木的高生长和径生长等4个方面作比较,得出墨西哥柏 车桑子混交模式的稳定性优于干香柏 车桑子混交模式。由于石质山地的土壤较为瘠薄,影响了乔木树种的生长,使两种乔灌混交林中乔木树种墨西哥柏和干香柏的生长高峰期提前在第3~4年到来。相比较墨西哥柏比干香柏更能适应试验区恶劣的自然条件,其造林后第6年树高和地径生长量仍达0.99 m和1.08 cm,而干香柏只有0.44 m和0.46 cm。     

湿地松和火炬松纯林和混交林生长比较

以湖北省荆门市彭山林场不同林龄的湿地松纯林、火炬松纯林和湿地松+火炬松混交林为研究对象,采用木材解析法,比较研究了湿地松、火炬松两个树种在纯林和混交林的生长特性,以了解两树种混交效果是否具有明显的增产效果。结果表明:与纯林相比,在15年时,湿地松和火炬松在混交林中直径分别增加了12.05%和10.60%,材积分别增加38.91%和24.25%。在所有5个混交林中,湿地松和火炬松的相对产量均大于1。湿地松和火炬松混交在生长量和材积上表现出正效应。在混交林中,湿地松获得更多的效应,但无论在纯林还是在混交林中,火炬松均比湿地松生长得好。