七叶树种间和种内生长与形态差异

七叶树(Aesculus spp.)是重要的药用经济树种,传统中药娑罗子即为七叶树种子,通常用于治疗胃寒腹胀、小儿疳积、痢疾等病症.国外在18世纪初就将欧洲七叶树(A.hippocastanum L.)种子和幼枝外皮的乙醇制剂用于解热和治疗痔疮、静脉曲张等疾病.     

A Danish example of optimal thinning strategies in mixed-species forest under changing growth conditions caused by climate change

In this study, we analyse the economic and managerial aspects of option values related to having a mixed-species stand. As an example, we look at a mixed Norway spruce and Sitka spruce stand in Denmark when timing and intensity of future climate, and its effect on tree growth, are uncertain. Assuming that tree growth follows a discrete non-stationary stochastic process, we use dynamic programming to optimise the harvest distribution between the two species.

The results show that facing growth uncertainty caused by potential climate change implies an option value. Such uncertainty can be a potential advantage as long as we are able to maintain flexibility, keep decisions open, and there is a chance that climatic change will benefit some species. We analyse the model under different uncertainty assumptions and show that the larger changes we expect, the higher is the option value at any time during the stand’s life and, hence, we keep, on average, both tree species in the stand for a longer period of time. Moreover, we find that the adjustments may take place rather late in the rotation, a result brought about by the significance of the option value, which makes it optimal to maintain a reasonable stocking of both species.     

复合经营猕猴桃光合日变化的初步研究

猕猴桃叶片光合速率日变化呈双峰曲线，不同龄叶片具有不同的光合速率。套种植物狗尾草、美洲黑杨和印尼大豆的光合速率日变化也基本呈一双峰曲线。套种可以明显降低中午猕猴桃光合“午睡”，增加光合速率与各环境因素的相关性，从空间上和时间上更充分地利用光能，从而改善猕猴桃冠幕微气候，提高光能利用率。     

不同立地长白落叶松净光合特征的研究

本文通过对不同立地、不同年龄段长白落叶松净光合速率与呼吸速率的测定 ,测定出了长白落叶松净光合速率和呼吸速率 ,以及长白落叶松净光合速率的日进程与季节进程。通过对比试验测定 ,得出长白落叶松以 10年生净同化率最高 ,值为 :0 .30 51mgCO2 m- 2 s- 1,四大林场中以哈尔滨林场的长白落叶松净同化率最高 ,值为 0 .1335mgCO2 m- 2 s- 1。长白落叶松CO2 补偿点为 130vpm ,光呼吸值为 4 0vpm     

森林火灾数量特征和火灾保险率的数学模拟

森林火灾保险是国内新设的保险种类,保险费率的确定是一个值得研究的问题。本文通过对福建省某地区火灾资料的分析,得出了年火灾发生次数和每次受灾面积的概率分布模型,应用计算机仿真技术(Monte-carlo方法)模拟了一定时期内年火灾次数和面积,并根据保险费率计算的有关理论和依据,确定了森林火灾保险费率的合理取值。     

Effects of Gliricidia sepium (Jacq.) Steud and Leucaena leucocephala (Lam.) de Wit on growth and development of Imperata cylindrica (L.) Raeuschel.

Field studies carried out in a forest transition site on a tropical Alfisol in southwestern Nigeria, show that shading by gliricidia (Gliricidia sepium (Jacq.) Steud) and leucaena (Leucaena leucocephala (Lam.) de Wit) hedgerow species reduced density of speargrass (Imperata cylindrica (L.) Raeuschel) by 67% and 51%, respectively. Shoot biomass of speargrass decreased by 81% and 78% in gliricidia and leucaena hedgerows, respectively. Reduction in speargrass rhizome biomass in gliricidia plots was 96% while rhizome reduction in the leucaena plots was nearly 90%. Rhizome mortality was significantly higher in gliricidia plots than in leucaena and control plots. The bulk of rhizomes was found between 10 cm and 20 cm of soil depth but rhizome did not penetrate further than 30 cm depth in the Alfisol in which this study was carried out. Gliricidia was better than leucaena hedgerow species in suppressing speargrass.     

Tropical Tree Growth and Longevity: Validation of Growth Simulation,a Bootstrapping Model

ABSTRACT

Growth Simulation, an analytical modeling technique, has been increasingly used in ecological studies and practical forestry applications where dendrochronology is not applicable. The technique uses randomly sampled diameter increments from tagged trees over a known time interval to assemble a statistical sample of lifetime growth trajectories. We carried out a validation of Growth Simulation using a temperate species in order to compare indirect model outputs with direct tree ring analysis. Rings were measured on sample disks cut from 55 pine branches ranging in age from 8–36 years. Assessments included lifetime growth rates, growth rate with respect to diameter and age, periodic annual increment (PAI), cross-referencing of rings by date, and autocorrelation of growth over successive periods. Tree ring analysis and Growth Simulation showed close correspondence for all parameters tested (maximum, median, and minimum growth rates; longevity estimates). Growth Simulation is found to be a robust and informative technique for studies of tropical tree growth, and is especially useful where analysis of tree rings is not feasible or when bootstrapping analysis of ring data is of interest.     

柔枝松引种试验初报

为了掌握柔枝松在中国的生长适应情况,对柔枝松引种后1 a生苗木的生长情况进行了研究,并选择乡土树种油松、华山松和白皮松作为对照。结果表明,柔枝松种源1和种源2的场圃发芽率分别为24.25%和25.25%,均低于油松(36.5%),但高于白皮松(18.25%)和华山松(13.25%);成活率比乡土树种低;柔枝松的苗高生长较慢,柔枝松种源1和种源2的1 a生苗苗高分别为3.1 cm?和3.6 cm?,低于油松(6.3 cm)、华山松(5.2 cm)、白皮松(4.3 cm);柔枝松种源1和种源2的1 a生地径,分别为0.175 cm?和0.178 cm,低于油松(0.208 cm)但与华山松(0.182 cm),与白皮松(0.178 cm)相差不大;柔枝松种源1和2主根平均长度分别达到了19.1 cm1、4.8 cm,均长于乡土树种,两个柔枝松种源之间相比,种源2优于种源1。     

Influence of host plant species on the development and reproduction of hawthorn spider mites

A leaf disc bioassay was employed to investigate the influence of host species of deciduous fruit trees, like apple, peach, plum, cherry and apricot, on the development and reproduction of the hawthorn spider mite Tetranychus viennensis Zacher in the laboratory under conditions of 25±1°C, 60±10% RH and a photoperiod of 16 h: 8 h light: dark. This was done by determining the duration of each life stage of the mites, the intrinsic rate of population increase (r _m ), mean generation time (T) and net reproductive rate (R ₀) of the spider mites on each of the host plant species. Differences in life table parameters of the spider mite among host plants were analyzed with the jack-knife method. The results indicated that plum might be the best suitable plant for the spider mite among the plants tested due to shorter developmental period and higher intrinsic rate of increase, whereas cherry and apricot were least suitable due to their long developmental duration and low intrinsic rates of increase. When the spider mites were transferred from apple to other fruit trees, negative effects on developmental duration, fecundity and life table parameters were found in the first generation, but the effects faded out in succeeding generations. When transferred onto plum and peach, the spider mite adapted to the new hosts in the second generation; however, on cherry and apricot, it adapted in the third generation. __________ Translated from Acta Ecologica Sinica, 2005, 27(7) [译自: 生态学报, 2005, 27(7)]     

A robust set of black walnut microsatellites for parentage and clonal identification

We describe the development of a robust and powerful suite of 12 microsatellite marker loci for use in genetic investigations of black walnut and related species. These 12 loci were chosen from a set of 17 candidate loci used to genotype 222 trees sampled from a 38-year-old black walnut progeny test. The 222 genotypes represent a sampling from the broad geographic distribution of the species. Analysis of the samples using the 12 loci revealed an average expected heterozygosity of 0.83, a combined probability of identity of 3×10⁻¹⁹, and a combined probability of exclusion for paternity analysis of >0.999. The 222 genotyped trees from the progeny test comprised 39 open-pollinated families, 29 of which (having at least five sampled progeny) were used to estimate the outcrossing rate for the progeny trial. The same 29 families were used to construct a Neighbor-Joining dendrogram based upon allele sharing between individuals. The multilocus estimate of the outcrossing rate was 100% (standard error of zero), higher than the 90% level found in previous studies at the embryo stage, suggesting that both artificial and natural selection against selfs may have occurred over the 38-year lifespan of the progeny trial. In the Neighbor-Joining dendrogram, the majority of the putative siblings grouped together in 21 out of the 29 families, showing that the microsatellites were able to discern most of the family structure in the dataset. Our results indicate that errors were sometimes committed during the establishment of the progeny test. This set of microsatellite loci clearly provides a powerful tool for future applications in black walnut.