鹞落坪保护区模式地植物及乡土观赏树种研究

首次详细记录了鹞落坪国家级自然保护区模式地植物及其命名过程,并介绍保护区内具有较高观赏价值的乡土木本植物186种,隶属于53科104属,其中观花树木类50种;观形树木类37种;观果树木类18种;观叶树木类15种;树桩盆景与盆花类15种;行道树类21种;垂直绿化类25种;观赏竹类5种。对观赏特性和园林用途进行了初步探讨,以期为城市绿化及相关研究与资源利用提供参考。     

福建地区马尾松生物量转换和扩展因子的影响因素

基于第8次国家森林资源清查福建省331块马尾松的固定样地调查数据,利用增强回归树法(BRT)研究地上生物量转换和扩展因子(BCEF)和地下BCEF的影响因素。研究结果表明:林分特征因子和地形因子是影响地上BCEF以及地下BCEF的主导因素,二者对地上BCEF影响的相对贡献率之和为87.20%、地下BCEF为86.59%。其中,龄组和坡向分别是林分特征因子和地形因子中影响地上BCEF的最大因素(41.13%和14.52%)。地上BCEF随龄组的增大而逐渐减小;在东南坡最大、西坡最小。此外,龄组和坡向分别是林分特征因子和地形因子中影响地下BCEF的最大因素(41.54%和15.16%)。地下BCEF随龄组的增大而逐渐减增大;在东南坡最小、西坡最大。土壤因子对地上BCEF以及地下BCEF的影响都较小(12.80%和13.41%),腐殖层厚度是土壤因子中影响地上BCEF以及地下BCEF的最大因素(9.02%和9.13%)。在所有的影响因素中,龄组对地上BCEF以及地下BCEF的影响均最大,依据龄组计算相应的BCEF或者建立林龄普适的BCEF模型,可以有效地提高生物量的估算精度。     

The phenology of the San Jose scaleQuadraspidiotus perniciosus [Hom.: Diaspididae] and its association with its natural enemies on almond trees in northern Greece

The phenology of the San Jose scale was studied in a heavily-infested almond orchard in northern Greece. It appears that the scale there completes 3 generations per year. The majority of the population hibernates as 1^st instar larvae. A series of releases were made using the introduced Hymenoptera parasiteProspaltella perniciosi Tower. Sampling results showed a very high mortality of the San Jose scale, Apart from the percentage due to climatic factors, the remainder is a result of the action of natural enemies. A considerable part of this action is attributable to the local entomophagous insects and especially the predators, of whichCybocephalus fodori Endrody-Younga appears to be the key species. The rest is attributable to the action of the released populations ofP. perniciosi. The main part of this paper was presented during the International Symposium held in Budapest (15–20 August 1983).     

Molecular Analysis of Zucchini yellow mosaic virus Isolates from Hangzhou, China

Isolates of Zucchini yellow mosaic virus were obtained from different cucurbit crops in Hangzhou city, China. The complete nucleotide sequences of four isolates and the 3′‐terminal sequences, including the coat protein coding region, of four others were determined and then compared with other available sequences. Phylogenetic analysis of the coat protein nucleotide sequences showed that these isolates fell into three significant groups, one of which (designated group III) consisted exclusively of Chinese isolates and is reported for the first time. Comparisons over the completely sequenced genomes showed that, typically for potyviruses, the 5′‐end of the genome was usually the most variable but that the group III isolate differed from the others most significantly in the N‐terminal part of the coat protein. Partially sequenced group III isolates also varied from other isolates in this region. Group III isolates appear to differ biologically from the other isolates because they do not cause symptoms in watermelon fruit but induce more severe symptoms on the watermelon leaves.     

Photosynthetic acclimation in trees to rising atmospheric CO2: A broader perspective

Analysis of leaf-level photosynthetic responses of 39 tree species grown in elevated concentrations of atmospheric CO₂ indicated an average photosynthetic enhancement of 44% when measured at the growth [CO₂]. When photosynthesis was measured at a common ambient [CO₂], photosynthesis of plants grown at elevated [CO₂] was reduced, on average, 21% relative to ambient-grown trees, but variability was high. The evidence linking photosynthetic acclimation in trees with changes at the biochemical level is examined, along with anatomical and morphological changes in trees that impact leaf- and canopy-level photosynthetic response to CO₂ enrichment. Nutrient limitations and variations in sink strength appear to influence photosynthetic acclimation, but the evidence in trees for one predominant factor controlling acclimation is lacking. Regardless of the mechanisms that underlie photosynthetic acclimation, it is doubtful that this response will be complete. A new focus on adjustments to rising [CO₂] at canopy, stand, and forest scales is needed to predict ecosystem response to a changing environment.Abbreviations A/C_i photosynthesis as a function of internal [CO₂] - J_max maximum rate of electron transport - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - Vc_max maximum rate of carboxylation The U.S. Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

Domestication of the neotropical tree Chrysophyllum cainito from a geographically limited yet genetically diverse gene pool in Panama

Species in the early stages of domestication, in which wild and cultivated forms co‐occur, provide important opportunities to develop and test hypotheses about the origins of crop species. Chrysophyllum cainito (Sapotaceae), the star apple or caimito, is a semidomesticated tree widely cultivated for its edible fruits; it is known to be native to the neotropics, but its precise geographic origins have not been firmly established. Here, we report results of microsatellite marker analyses supporting the hypothesis that the center of domestication for caimito was the Isthmus of Panama, a region in which few crop species are believed to have originated, despite its importance as a crossroads for the dispersal of domesticated plants between North and South America. Our data suggest that caimito was domesticated in a geographically restricted area while incorporating a diverse gene pool. These results refute the generally accepted Antillean origin of caimito, as well as alternative hypotheses that the species was domesticated independently in the two areas or over a broad geographic range including both. Human‐mediated dispersal from Panama to the north and east was accompanied by strong reductions in both genotypic and phenotypic diversity. Within Panama, cultivated and wild trees show little neutral genetic divergence, in contrast to striking phenotypic differentiation in fruit and seed traits. In addition to providing a rare example of data that support the hypothesis of a narrow geographic origin on the Isthmus of Panama for a now widespread cultivated plant species, this study is one of the first investigations of the origins of an edible species of the large pantropical family Sapotaceae.     

两种光强下木质藤本与树木幼苗的竞争关系

 为了探讨木质藤本和树木幼苗的相互作用关系,对两种光强(4%和35%的光强)、4种竞争处理下(全竞争、地上竞争、地下竞争和无竞争),一种 需光木质藤本(刺果藤(Byttneria grandifolia))和3个树种(耐荫种：五桠果木姜子(Litsea dilleniifolia)和绒毛番龙眼(Pometia tomentosa);需光种：羊蹄甲(Bauhinia variegata))幼苗的地上部分和地下部分的竞争关系进行了研究。结果表明：木质藤本的竞争显著影响 着3种树木幼苗的光合能力、形态特征和生长,但生长环境的不同光强影响地上部分竞争和地下部分竞争的相对强度。在低光下,地上部分竞争 比地下部分竞争对3种树木幼苗的相对生长速率(Relative growth rate,RGR)和光合能力造成更大的影响;而高光下,地下竞争对树木幼苗的 生长有更强的抑制作用。不同的竞争处理和光强对树木幼苗的生物量积累造成显著的影响。光强对3种树种的比叶面积(Specific leaf area, SLA)和叶面积比(Leaf area ratio,LAR)有显著的抑制作用,但竞争只对需光的羊蹄甲的SLA和LAR有显著影响。不同的光照和竞争处理之间, 同种植物表现出不同的表型特征。由于竞争的影响,苗木在形态上较为矮小、叶片数目较少、叶面积减小,但是长细比改变较少 。     

Post-autotomy regeneration of respiratory trees in the holothurian Apostichopus japonicus (Holothuroidea, Aspidochirotida)

Specialised respiratory organs, viz. the respiratory trees attached to the dorsal part of the cloaca, are present in most holothurians. These organs evolved within the class Holothuroidea and are absent in other echinoderms. Some holothurian species can regenerate their respiratory trees but others lack this ability. Respiratory trees therefore provide a model for investigating the origin and evolution of repair mechanisms in animals. We conducted a detailed morphological study of the regeneration of respiratory trees after their evisceration in the holothurian Apostichopus japonicus. Regeneration of the respiratory trees occurred rapidly and, on the 15th day after evisceration, their length reached 15–20 mm. Repair involved cells of the coelomic and luminal epithelia of the cloaca. Peritoneocytes and myoepithelial cells behaved differently during regeneration: the peritoneocytes kept their intercellular junctions and migrated as a united layer, whereas groups of myoepithelial cells disaggregated and migrated as individual cells. Although myoepithelial cells did not divide during regeneration, the peritoneocytes proliferated actively. The contractile system of the respiratory trees was assumed to develop during regeneration by the migration of myoepithelial cells from the coelomic epithelium of the cloaca. The luminal epithelium of the respiratory trees formed as a result of dedifferentiation, migration and transformation of cells of the cloaca lining. The mode of regeneration of holothurian respiratory trees is discussed. This work was funded by a grant from the Russian Foundation for Basic Research (project no. 08–04–00284) to I.Y.D. and by a grant from the Far Eastern Branch of the Russian Academy of Sciences and the Russian Foundation for Basic Research (project no. 09–04–98547) to T.T.G.     

Non‐timber Forest Product Harvest does not Affect the Genetic Diversity of a Tropical Tree Despite Negative Effects on Population Fitness

The level of genetic diversity in a population can affect ecological processes and plant responses to disturbance. In turn, disturbance can alter population genetic diversity and structure. Populations in fragmented and logged habitats often show reduced genetic diversity and increased inbreeding and differentiation. Long‐term harvesting of wild plants (for foliage, bark, and roots), can affect population genetic diversity by altering individual fitness and genetic contribution. Our understanding of these changes in genetic diversity due to the harvesting of plant organs is still limited. We used nine microsatellite markers to study the effect of long‐term bark and foliage harvest by Fulani people on the genetic diversity and structure of 12 populations of African mahogany (Khaya senegalensis) in Benin. We sampled 20 individuals in each population to test the effect of harvesting. For each population, we divided the samples equally between seedling and adults to test if the effects are stronger in seedlings. We found moderate genetic diversity (H_e = 0.53 ± 0.04) and weak but significant differentiation among local populations (F_ST = 0.043, P < 0.001). There was no significant effect of harvest on genetic diversity or structure, although previous work found significant negative effects of harvest on the reproduction of adults, offspring density, and population fitness. Our results suggest that demographic responses to disturbance precede a detectable genetic response. Future studies should focus on using parentage analysis to test if genotypes of harvested parents are directly represented in the offspring populations.     

Competition and patterns of resource use among seedlings of five tropical trees grown at ambient and elevated CO2

Summary Seedlings of five tropical trees, Cecropia obtusifolia, Myriocarpa longipes, Piper auritum, Senna multijuga and Trichospermum mexicanum, were grown both as individuals, and in competition with each other at ambient (350) and two levels of elevated CO₂ (525 and 700 l l^-1) for a period of 111 days. Growth, allocation, canopy architecture, mid-day leaf water potential and soil moisture content were assessed three times over this period for individually grown plants, and at the end of the experiment for competitively grown plants. In addition, leaf photosynthesis and conductance were assessed for the individually grown plants midway through the experiment, and light profile curves were determined for the competitive arrays at three stages of development. Elevated CO₂ did not affect photosynthesis or overall growth of the individually-grown plants but did affect canopy architecture; mean canopy height increased with CO₂ in Piper and Trichospermum and decreased in Senna. Stomatal conductance decreased slightly as CO₂ increased from 350 to 525 l l^-1 but this had no significant effect upon whole plant water use of leaf water potential. Soil moisture content for the individuals increased marginally as CO₂ increased, but this did not occur in the competitive arrays. There was a marked effect of CO₂ upon species composition of the competitive arrays; Senna decreased in importance as CO₂ increased while Cecropia, Trichospermum and Piper increased in importance. Stepwise regression analysis using competitive performance as the independent variable, and the various morphological and physiological parameters measured on the individually grown plants as independent variables, suggested that canopy height was the single most important variable determining competitive ability. Also significant were photosynthetic rate (particularly at low light levels) and allocation to roots early in the experiment. Light profiles in the canopy revealed that less than 15% of incident light penetrated to the level of mean canopy height. Results suggest that competition for light was the major factor determining community composition, and that CO₂ affected competitive outcome through its affect upon canopy architecture.This study was supported by a grant from the US Department of Energy