Retention-tree groups in clear-cuts: Do they constitute ‘life-boats’ for spiders and carabids?

Green-tree retention aims at maintaining biodiversity while harvesting timber, but knowledge of its efficiency is still limited. Green-tree retention may function as a ‘life-boat’ for organisms, maintain structural features, or create stepping-stones in the harvested landscape. The aim of this study is to determine whether larger retention-tree groups established in clear-cuts maintain forest species better than smaller ones. We posed hypotheses for different habitat affinity groups of spiders and carabids, and tested them in Eastern Finland with 11 retention-tree groups, 0.09–0.55 ha in size (47–385 trees per tree group). Although some of the analysed species responded as expected, we did not find unambiguous support for the hypotheses that (1) species requiring forest and/or (medium-) moist habitat should be more abundant in larger retention-tree groups, (2) species requiring (semi-) open and/or (medium-) dry habitat should be more common in smaller retention-tree groups, and (3) species indifferent with respect to light intensity and moisture should be caught in equal numbers in all retention-tree groups irrespective of their size. However, the mean numbers of individuals of many forest species and/or species requiring (medium-) moist habitat decreased over the 3 years after logging in all retention-tree groups, whereas the mean numbers of many species of (semi-) open and/or (medium-) dry habitat increased over the 3 years after logging. Furthermore, species composition changed from the pre-treatment year for spiders. We conclude that green-tree retention is justified because (1) retention-tree groups tend to maintain some forest species, thereby mitigating the effects of clear-cutting, at least in the short term, (2) they provide dead wood, large old trees, and other structural features, and (3) there are gaps in our ecological knowledge that warrant the adoption of the precautionary principle. However, as there are economic costs associated with the establishment of retention-tree groups, their ecological benefits as compared to other approaches aimed at maintaining biodiversity should be assessed carefully.     

橡胶树树皮坏死:症状学、病原学、流行病学方面的发展和树干生理病症的发因

橡胶树排胶障碍是制约全球橡胶种植园发展的主要因素,它是由以下两个不同病症导致的:(1)割面干涸(TPD)-过度割胶引起的可逆生理反应,(2)割面树皮坏死(BN)-由橡胶树根颈韧皮部扩展的不可逆病变。树皮坏死(BN)目前危害了世界大部分胶园,胶园受害严重度取决于橡胶品种、树龄、种植地和种植地区。橡胶树树皮病的多态性一直是一个有争议的问题,通过对许多胶园的调研,该问题最近得到了解决。虽然前期和最近的病原分析不具决定性,但是环境因素却显示出同树皮坏死有联系。在对近期开割的胶园进行流行病调查,发现早期患病胶树地点呈非随机性。这些易发病区主要靠近沼泽地、路旁、风干行、原推土机过道、树林树桩残余地和斜坡缓冲地段的附近区域。在树皮坏死发生区,虽然没有发现与土壤化学因素有明显的关系,但是,土壤物理分析(如透度法)却表明,土壤的较高紧实度常同患病胶树的根系生长较弱有关联。另外,通常在芽接点接合处可以很好地观察到树皮坏死早期症状。通过PMS压力室获得的大量可比生态生理的测量数据显示,患病胶树呈现水分协迫特征,意味着病树树干同其根系存在着一种非理想的维管关系。因此,同土壤紧实度相关的土壤缺水状况、旱季不能满足胶树水分需求的脆弱根系、被扰乱的树液流动和土壤排水等因素的共同作用,被怀疑是诱导树干接芽区树皮坏死(坏死向上扩展到割面) 生理的一个主要外部诱因。在这些协迫的作用下,细胞与分子研究显示,橡胶树生理失调是导致树皮坏死迅速扩展的原因。在这些协迫的作用下,在胶树芽接部位的细胞破裂,释放极具扩散性的高浓度氰化物。在患病胶树的韧皮部生氰和解氰活动的极不协调,以及氰化物的释放,导致其周围的细胞受到毒害。最后, 这样一种多学科的研究方法为由协迫诱导的多因素生理病害研究提供了一个完整的新模式。     

云南东川华山松健康树皮中矿质元素的测定

采用高压硝化罐法硝化样品,用ICP-OES测定了健康华山松树皮中Ca、Mg、K、P、Fe、Mn、B、Zn8种矿质元素含量,同时用半微量法测定了Ag等42种元素,结果表明:(1)健康华山松树皮中Ca>B>K>Fe>Mg>P>Mn>Zn。(2)半微量法测定的42种元素中证明了元素Se的存在,没有测定到Ho、Tl、Pt、Tm。     

树脂生物合成的分子遗传新进展和增强针叶树防御的遗传工程策略

Since the first terpenoid synthase cDNA was obtained by the reverse genetic approach from grand fir, great pro-gress in the molecular genetics of terpenoid formation has been made with angiosperms and genes encoding a monoterpene synthase, a sesquiterpene synthase, and a diterpene synthase. Tree killing bark beetles and their vectored fungal pathogens are the most destructive agents of conifer forests worldwide. Conifers defend against attack by the constitutive and inducible production of oleoresin that accumulates at the wound site to kill invaders and both flush and seal the injury. Although toxic to the bark beetle and fungal pathogen, oleoresin also plays a central role in the chemical ecology of these boring insects. Re-cent advances in the molecular genetics of terpenoid biosynthesis provide evidence for the evolutionary origins of oleoresin and permit consideration of genetic engineering strategies to improve conifer defenses as a component of modern forest bio-technology. This review described enzymes of resin biosynthesis, structural feathers of genes genomic intron and exon or-ganization, pathway organization and evolution, resin production and accumulation, interactions between conifer and bark beetle, and engineering strategies to improve conifer defenses.     

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.     

Studies on the abundance, biology and harmfulness of leaf beetles (Coleoptera: Chrysomelidae) in natural bush vegetation in Isparta, Turkey

Leaf beetle occurrence and abundance on certain shrubs and bushes were surveyed during 2002–2003 in several natural habitats of Isparta. The 34 leaf-beetle species collected are listed and classified according to their relative percentage of the total caught and to their associated host plants. In all habitats sampled, leaf beetles showed a preference for plants from the genera Quercus and Crataegus. Some abundant species causing serious damage to their food plants are discussed.     

Tree bark as a non-timber forest product: The effect of bark collection on population structure and dynamics of Garcinia lucida Vesque

A 2-year demographic field study was carried out on the understorey tree Garcinia lucida in the humid Atlantic forests of South Cameroon. The bark and the seeds of the species are exploited for medicinal purposes and palm wine processing in West and Central Africa. The bark is often removed over almost the entire circumference of the stem, leading to high mortality rates. The goal of the study was to assess the impact of bark harvesting on population structure and dynamics, in order to obtain an indication to what extent the actual harvesting practices can be sustained for longer periods, and to provide information on the future availability of the resource. Comparison of populations that had been subject to different harvest regimes allowed assessment of the effects of G. lucida bark harvesting on population stand structure. In lightly exploited populations, unharvested individuals represented more than the half of the trees (>10 cm DBH), while this was only one-third in heavily exploited stands. The percentage of dead exploited trees (>20 cm DBH) was more than 40 and 70%, for lightly and heavily exploited populations, respectively. This reflects the high intensity of bark harvesting, mainly directed at large trees. For the assessment of bark harvesting on population dynamics, we constructed matrix models for each of the three common bark harvest practices: (1) partial debarking of stem, (2) ring-barking trees and (3) felling trees at approximately 1 m height above ground level to extract bark. For all harvest practices, the asymptotic population growth rates (λ) were not significantly different from 1 indicating that populations were neither growing nor decreasing in size. Nevertheless, model projections showed that the stock of available trees decreased. Under an annual regime of partial debarking of all trees >10 cm DBH, the amount of harvestable trees gradually declined and reached 50% of the initial size after 20 years. For ring-barking and felling trees, the projections showed a sharp drop in the amount of harvestable trees directly after the start of the simulations, and the amount continued to decline below 4% of the initial size under an annual harvest regime. Even after a long time, populations did not recover to their pre-harvest numbers. The stable size of harvested populations predicted by λ values suggest that current harvest practices of bark do not jeopardize the future existence of G. lucida populations. However, as the frequently applied harvest practices of ring-barking and felling strongly reduced the stock in our simulations, commercial bark exploitation cannot be sustained over long periods. Nevertheless, as long as populations can recover from the loss of exploited individuals, by continuous recruitment, there is still prospect for sustained bark extraction.     

老秃顶子国家级自然保护区小蠹虫发生危害调查

在老秃顶子国家级自然保护区共采到小蠹虫29种,隶属4亚科15属,其中红松根小蠹Hy-lastes plumbeusBlandford、东北四眼小蠹Polygraphus sachalinensisEggers、中穴星坑小蠹Pityo-genes chalcographasLinnaeus、落叶松八齿小蠹IpssubelongatusMotschuleky、六齿小蠹I.acuminatusGyllenhal等为优势种,主要危害衰弱木、濒死木、枯萎木及风倒雪压木等,少数种类如纵坑切梢小蠹Tomicus piniperda Linnaeus、黄须球小蠹Sphaerotrypes coimbatorensisStebblng等危害健康树木。不同海拔高度及不同类型的林分中,小蠹虫的种类存在明显差异。及时清除、集中处理风倒木是控制虫源,减轻危害的重要措施。     

Influence of Bark Pyrolysis Technology on Yield

INTRODUCTION Bark accounts for 10% of a log and there are about 2.5 billion m3 of logs consumed every year all over the world, which produce 250 million m3 of bark. It will bring a huge amount of money if we make good use of the bark as a raw material of industry. Since middle- and small- diameter classes wood of poor quality and remnant products account for an important part of forest resource, we should advance comprehensive utilization energetically and orient it to whole-tree utilizati…     

芒果皮粗多糖提取的影响因素及工艺的研究

以芒果皮渣为原料,就粗多糖提取的影响因素及工艺进行了研究.采用单因素和L9（33）正交试验,研究了料液比、温度和时间等因素对多糖提取率的影响.结果表明,料液比和温度是影响多糖提取率的主要因素;确定的最佳提取工艺条件为：料液比1：5,温度90℃,时间2 h.在最佳提取工艺时,芒果皮中粗多糖提取率高达3.538 2%.