广东鹤山、东莞莲花山小蛾类（Ⅰ）

对广东省鹤山和东莞莲花山自然保护区的小蛾类昆虫进行调查，计有8科35属43种。其中广东新记录种14种。     

围栏封育对温性草甸草原植物群落构成及生态位特征的影响

为明确温性草甸草原群落构成和生态位对围栏封育的响应,运用了Levins生态位指数和Pianka生态位重叠指数以及物种多样性指数分析围栏内外植物种对资源的利用情况和种间竞争情况。结果表明:围栏封育显著促进退化草地植被恢复,植被地上生物量和地下生物量分别较对照提高255.06%,51.06%;物种多样性与丰富度分别增加了10.36%,10.34%。围封样地内生态位宽度排名前2位的植物为囊花鸢尾和羊草,生态位宽度值分别为0.921和0.873;自由放牧样地生态位宽度排在前2的植物为蒲公英和寸草苔,生态位宽度值依次为0.912和0.791。围栏封育可以显著提高草地生产力,并且对物种多样性也有一定的促进作用,是应对退化温性草甸草原恢复的有效措施;与自由放牧相比,围栏封育增加了群落植物种整体生态位重叠值和种间竞争。     

Comparison of sympatric freshwater turtle populations from an urbanized Sydney catchment

• 1. Australian freshwater turtles are widely distributed throughout the continent, and in each river catchment there are at least two taxa. In south‐eastern Australia Chelodina longicollis and forms of Emydura macquarii co‐habit within a waterway, although they have been shown to partition habitat within the water column in non‐urban bodies of water. Limited comparative data are available for the urban populations.
• 2. Within urban Sydney C. longicollis (eastern long‐necked turtle) and Emydura macquarii dharuk (Sydney short‐necked turtle) share habitat. However, in contrast with non‐urban studies of C. longicollis and other sympatric E. macquarii taxa, it was observed that the population profile of the two species was similar at all sites, and that C. longicollis were present in greater numbers than E. m. dharuk.
• 3. The continued degradation of preferred habitat, low recruitment, and potential competition from introduced turtles place both species in a precarious position.
• 4. The shallow, impounded waterways of the regulated urban bodies of water align more closely with the preferred habitat of C. longicollis than with that of forms of E. macquarii, which prefer deeper flowing waters or large wetlands adjacent to rivers. Emydura m. dharuk may be at greatest risk of extinction in urban areas.
• 5. Across urban Sydney, the low numbers of E. m. dharuk compared with C. longicollis may be due to the lack of mobility of E. m. dharuk such that individuals tend to be stranded in sub‐optimal habitat. In contrast, C. longicollis has a greater propensity for overland movement, and a preference for the ‘new habitat’ resulting from urban impacts on the associated waterways, and thus appears to be able to utilize these modified urban waters more successfully.

Copyright © 2008 John Wiley & Sons, Ltd.     

科尔沁沙地榆树疏林草地物种多样性及乔木种群空间格局

应用多样性指数对科尔沁沙地榆树疏林草地的物种多样性进行了研究,并用空间格局指数测定了乔木种群的分布格局。结果表明,灌木层多样性较低,而草本层物种多样性较高。在生活型功能群中,一、二年生草本处于优势地位,多年生草本具有稳定群落的效应;在生态功能群中,旱生、中生植物占有主体优势,但在群落中又存在植物功能互补效应。乔木种群的分布格局呈现出聚集分布,在其发育过程中具有不同的动态变化特征,即幼苗、幼树阶段为聚集分布,到了成树阶段为随机分布。     

The process of decline of an endangered tree species,Pinus armandii Franch. var.amamiana (Koidz.) Hatusima, on the southern slope of Mt. Hasa-dake in Yaku-shima Island

The process of decline of an endangered tree species,Pinus armandii var.amamiana, was monitored on the southern slope of Mt. Hasa-dake in Yaku-shima Island from 1994 to 1998. There are 163 trees ofP. armandii var.amamiana over 1.3 m in height. They are distributed on steep ridges and rocks with a thin soil layer mostly consisting of friable granite. During the monitoring period, 21 trees ofP. armandii var.amamiana died and the mortality rate was 12.9%. Dead trees were categorized into three types: standing, uprooted and landslide. The uprooted- and landslide-typed dead trees were found only after a severe typhoon struck Yaku-shima Island. This suggests that the combination of fragile site conditions and severe typhoons play an important role in the process of decline ofP. armandii var.amamiana. The standing-typed dead trees were presumed to have been killed by pine wilt disease, accounting for 71.4% of the dead trees. However,Bursaphelenchus xylophilus, the cause of pine wilt disease, was not detected from any of the wood chips or branch samples from the standing-typed dead trees ofP. armandii var.amamiana. This might indicate that some factor(s) other than pine wilt disease could be responsible for the standing-typed death ofP. armandii var.amamiana in natural habitats. A part of this paper was presented at the 109th Meeting of the Japanese Forestry Society.     

城市秋色叶树种资源应用探讨

秋色叶树种在我国园林造景中具有举足轻重的作用。为了合理开发和利用秋色叶树种资源,笔者总结了目前在我国园林中广泛应用的秋色叶树种资源,分析了它们在城市园林中的应用情况及应用方式,并指出了一些今后可供利用的秋色叶树种资源。     

北部湾鱼类多样性及优势种的时空变化

根据2007年在北部湾进行的4季渔业资源底拖网调查资料,对该海域鱼类的种类组成、物种多样性和优势种的时空变化进行分析.本次调查共捕获鱼类323种,隶属于18目101科,以发光鲷(Acropoma japonicum)、黄斑M(Leiognathus bindus)、竹??鱼(Trachurus japonicus)、二长棘鲷(Parargyrops edita)和大头白姑鱼(Argyrosomusmacrocephalus)为主要优势种.分析结果表明,北部湾鱼类的优势种更替明显,总体趋势为k选择种类(以红笛鲷和黑印真鲨等为代表)被r选择种类(发光鲷、鲾科和天竺鱼科等为代表)所替代,即寿命长、个体大和营养级高的鱼类种类减少,寿命短、个体小和营养级较低的种类增多.鱼类的Shannon-Wiener多样性指数(H)以共同渔区北部海域最高(3.60),东北部海域次之(3.58),共同渔区南部海域最低(2.35),四季多样性指数为2.96～3.77,平均3.31.2007年多样性指数比 1992-1993年低,但高于1998-1999年,表明近年来该海域捕捞压力有所减缓,使得渔业资源有一定的恢复.本研究旨在了解北部湾生物多样性和优势种的动态变化及演替状况,为该海域渔业资源的合理开发与可持续利用对策提供科学依据.     

新疆草地优势种植物相对生物量沿海拔梯度变化特征

优势种作为草地生态系统中地上生物量的主要贡献者,其生物量既受到环境因素的影响,也受到共存种种间关系的影响.然而,由于物种的不同和环境梯度的差异,目前有关优势种生物量与环境因素关系的研究,尚未获得一致性的结论.基于此,本研究以2011-2013年对新疆9种草地类型397个样地中优势种相对生物量的调查数据为基础,首先统计了...     

遮荫下2种热带树苗叶片光合特性和抗氧化酶系统对自然降温的响应

选取 2种遮荫条件下 (8%、2 5 %全光照 )西双版纳地区热带雨林上层树种滇南红厚壳和中层树种玉蕊的幼苗 ,测定了雨季末自然降温过程中 2种植物叶片光合特性、抗氧化酶 (SOD、CAT、APX)活性、丙二醛 (MDA)含量的变化。研究结果表明 :低温使 2种植物单位面积叶绿素含量和净光合速率明显下降 ,生长在中等光强下的幼苗比低光强下的幼苗下降的比率大 ,滇南红厚壳比玉蕊下降的比率大。在降温初期 ,即从 10月到 12月初 ,2种光强下 2种植物SOD和APX活性上升 ,CAT活性出现波动 ,黎明光化学效率和MDA含量基本没有变化 ,光合机构没有受到氧化破坏。 12月末 ,中等光强下滇南红厚壳黎明光化学效率降低 ,SOD和APX活性有所下降 ,MDA含量显著上升 ;而低光强下的滇南红厚壳和 2种光强下玉蕊SOD和APX活性仍在上升 ,MDA含量变化较小。这表明 ,2种光强下 2种热带树苗是以不同的方式响应自然降温 ,低温对中等光强下的植物比低光强下的影响大 ,上层树种滇南红厚壳受到的影响比中层树种玉蕊大。同时 ,根据降温过程中抗氧化酶活性和MDA含量的变化 ,大致可将西双版纳热带雨林幼苗对低温的响应分为 2个阶段 ,即第 1阶段为低温适应阶段 ,抗氧化酶活性上升 ,光合机构没有受到明显的氧化破坏 ;第 2阶段 ,中等光强下滇南红厚壳抗氧化酶     

The role of disturbance severity and canopy closure on standing crop of understory plant species in ponderosa pine stands in northern Arizona,USA

Concerns about the long-term sustainability of overstocked dry conifer forests in western North America have provided impetus for treatments designed to enhance their productivity and native biodiversity. Dense forests are increasingly prone to large stand-replacing fires; yet, thinning and burning treatments, especially combined with other disturbances such as drought and grazing, may enhance populations of colonizing species, including a number of non-native species. Our study quantifies plant standing crop of major herbaceous species across contrasting stand structural types representing a range in disturbance severity in northern Arizona. The least disturbed unmanaged ponderosa pine stands had no non-native species, while non-native grasses constituted 7–11% of the understory plant standing crop in thinned and burned stands. Severely disturbed wildfire stands had a higher proportion of colonizing native species as well as non-native species than other structural types, and areas protected from grazing produced greater standing crop of native forbs compared to grazed unmanaged stands. Standing crop of understory plants in low basal area thinned and burned plots was similar to levels on wildfire plots, but was comprised of fewer non-native graminoids and native colonizing plants. Our results also indicate that size of canopy openings had a stronger influence on standing crop in low basal area plots, whereas tree density more strongly constrained understory plant standing crop in dense stands. These results imply that treatments resulting in clumped tree distribution and basal areas <10 m² ha⁻¹ will be more successful in restoring native understory plant biomass in dense stands. Multiple types and severity of disturbances, such as thinning, burning, grazing, and drought over short periods of time can create greater abundance of colonizing species. Spreading thinning and burning treatments over time may reduce the potential for non-native species colonization compared to immediately burning thinned stands.