林业有害植物金钟藤新枝在海南的月生长动态

【背景】近20多年来,金钟藤在海南和广东异常快速生长,对生物多样性和林业生产破坏严重。观测金钟藤的月生长动态,了解其在海南的生长量,能够为金钟藤的合理防治提供参考。【方法】采用定点定时观测法,对海南3个市县3种不同生境的金钟藤新枝的月生长量进行测定。【结果】金钟藤在海南全年可生长,一新枝月平均生长134 cm,全年累计平均生长1607 cm。金钟藤全年有2个生长高峰期,分别在4月和9月,其中4月平均生长206 cm,9月187 cm。金钟藤在11月生长量最小,平均生长86 cm。金钟藤在1—9月生长较快,一新枝累计平均生长1326 cm,占全年生长量的82.5%;在10月至12月生长缓慢,一新枝累计平均生长281 cm,占全年生长量的17.5%。不同生境之间的金钟藤生长有极显著差异,月平均生长量从高到低顺序为定安188 cm白沙131 cm五指山83 cm。金钟藤种子在3—7月均可萌发,花果期在4—7月。在海南月平均温度17~28℃、月平均降雨量28~396 mm的自然环境范围内,金钟藤的生长量与温度和降雨量没有显著相关性。【结论与意义】金钟藤在海南光照充足的生境里快速生长扩散,月平均生长量高达188 cm,其生长与生境、海拔和植被密切相关。     

海南典型有害植物的入侵扩散机理研究进展

有害植物成灾会对农林业生态系统、经济和环境造成巨大影响。本文对海南典型入侵植物薇甘菊、假臭草及土著灾变植物金钟藤的成灾扩散机理研究做一综述,以期为海南有害植物的研究和管理提供依据。自然及人为干扰造成的薇甘菊匍匐茎克隆片段有较高的再生能力,其再生能力和生长与储存在节间和叶子中的资源呈正相关。假臭草随土壤养分条件的改善比本地种获利更多,说明农田施肥等干扰因素可能促进假臭草相对于本地种的种群优势。金钟藤已扩散至海南五指山有旅游活动的自然林;调查和移栽试验发现,其可能是先在受干扰严重的林缘和旅游小径边定植,之后通过匍匐和攀爬生长扩散至附近的自然林。这些结果强调了人类活动、高养分条件及物种自身性状等在有害植物成灾中的作用。未来仍需系统、深入地研究有害植物成灾扩散的机理及其控制对策,为减弱有害植物的扩散和危害提供参考,并为海南国际旅游岛的建设提供安全保证。     

三种植物对狭胸散白蚁的毒杀效果

测定并比较3种植物对狭胸散白蚁Reticulitermesangustatus的毒杀效果,为应用防治狭胸散白蚁提供理论基础。本文采用闹羊花Rhododendron molle、博落回Macleaya cordata、除虫菊Pyrethrum cinerariifolium 3种常见植物为药源,选取其药用部位打成粉末,以玉米芯粉为对照,以狭胸散白蚁为靶标,测试其毒杀作用、传毒效果和趋避效果。结果表明:对狭胸散白蚁的毒杀效果以除虫菊和闹羊花为最好,当药粉质量分数达到80%,实验第7天时闹羊花和除虫菊白蚁处理组校正死亡率达到100%。传毒效果以除虫菊相对最好。随着染毒时间延长和中毒白蚁数量的增加,传毒效率也相应提高。3种植物均有一定的驱避效果,且以博落回的趋避作用最小。因此,这3种植物可用于防治狭胸散白蚁。     

Shape of leaf photosynthetic electron transport versus temperature response curve is not constant along canopy light gradients in temperate deciduous trees

Responses of foliar light-saturated net assimilation rate (A_max), capacity for photosynthetic electron transport (J_max) and mitochondrial respiration rate (R_d) to long-term canopy light and temperature environment were investigated in a temperate deciduous canopy composed of Populus tremula L. in the upper (17–28 m) and of Tilia cordata Mill. in the lower canopy layer (4–17 m). Climatic measurements indicated that seasonal average daily maximum air temperature (T_max) was 5·5 °C (range 0·7–10·5 °C) higher in the top than in the bottom of the canopy, and strong positive correlations were observed between T_max and seasonal average integrated quantum flux density (Q_int), as well as between seasonal average daily mean temperature and Q_int. Because of changes in leaf dry mass and nitrogen per unit area, A_max, J_max, and R_d scaled positively with Q_int in both species at a common leaf temperature (T). According to J_max versus T response curves and dark chlorophyll fluorescence transients, photosynthetic electron transport was less heat resistant in P. tremula with optimum temperature of J_max, T_opt, of 33·5 ± 0·6 °C than in T. cordata with T_opt of 40·7 ± 0·6 °C. This difference was suggested to manifest evolutionary adaptation of photosynthetic electron transport to cooler environments in P. tremula, the range of which extends farther north than that in T. cordata. Possibly because of acclimation to long-term canopy temperature environment, T_opt was positively related to Q_int in P. tremula, foliage of which was also exposed to higher irradiances and temperatures, but not in T. cordata, in the canopy of which quantum flux densities and temperatures were lower, and gradients in the environmental factors less pronounced. Parallel to changes in T_opt, the activation energy for photosynthetic electron transport decreased with increasing Q_int in P. tremula, indicating that J_max of leaves acclimated to colder environment was more responsive to T in lower temperatures than that of high T acclimated leaves. Similar alterations in the activation energy for mitochondrial respiration rate were also observed, indicating that acclimation to temperature of mitochondrial and chloroplastic electron transport proceeds in a co-ordinated manner, and possibly involves long-term changes in membrane fluidity properties. We conclude that, because of correlations between temperature and light, the shapes of J_max versus T, and R_d versus T response curves vary within tree canopies, and this needs to be taken account in modelling whole canopy photosynthesis.     

水青冈林中两种鹅耳枥种子萌发和幼苗的生存与生长（英文）

 千金榆(Carpinus cordata var．chinensis)和千筋树(Carpinus fargesiana)是四川省北部山地水青冈林中的两种主要落叶阔叶树。两种植物种子萌发和幼苗生存与生长的实验研究结果显示：千金榆种子秋季成熟落地后有一年多的休眠期,种子主要在落地后的第二和第三个生长季萌发;千筋树种子成熟落地后有的可在来年萌发,但大部分是在第二个生长季萌发;由于每2～3年两种树就有一个较大的结实年,每年都会有一些新的幼苗在林中出土;尽管两种树是耐荫的,但幼苗在较好光照条件下(如林窗)生存和生长明显好于在林冠遮荫的地方;施肥会加速幼苗的死亡,特别是在阴暗的林下,但在光照较好的条件下能促进幼苗的生长。结果说明两种鹅耳枥的幼苗可以在林下持续存在,但只有在较好的光照条件下,如稀疏的林冠下或林窗下才会有明显的净生长。     

薇甘菊对香港郊野公园植物群落危害的分析

从薇甘菊(Mikania micrantha)对不同类型群落的危害,群落中各植物种类受薇甘菊危害的程度,以及薇甘菊与群落中主要乔木和灌木的种间联结性等方面,对香港郊野公园植物群落受薇甘菊危害状况进行了分析。研究样地所在的植被受薇甘菊的危害严重,草灌丛中薇甘菊的平均覆盖率高达80%,灌木群落中薇甘菊的平均覆盖率为60%左右,常绿阔叶林中的薇甘菊覆盖率平均约为30%。对香港郊野公园受薇甘菊危害的植物种类分析表明:受薇甘菊危害最大的主要是乔木和灌木,草本和藤本的受害比例和受害程度相对较小。受薇甘菊危害的乔木有30种,占群落中乔木的62.50%;受薇甘菊危害的灌木有29种,占群落中灌木的70.73%;受薇甘菊危害的草本植物有10种,占群落中草本植物的33.33%。通过无样方法采用2×2列联表的χ2检验对薇甘菊与群落中主要乔木和灌木的种间联结性分析表明:与薇甘菊呈正联结的乔木有12种,占主要乔木(28种)的42.86%,这些种大多是阳生性乔木;与薇甘菊呈负联结的乔木有16种,占主要乔木的57.16%。与薇甘菊呈正联结的灌木有11种,占主要灌木(19种)的57.89%,多是阳生性灌木;与薇甘菊呈负联结的灌木有8种,占主要灌木的42.11%,这些种大多数也是阳生性灌木,仅九节是耐阴性灌木。     

CHEMICAL DEFENSE AGAINST HERBIVORY IN THE ANTARCTIC MARINE MACROALGAE IRIDAEA CORDATA AND PHYLLOPHORA ANTARCTICA (RHODOPHYCEAE)

Iridaea cordata (Turner) Bory and Phyllophora antarctica A. et E. S. Gepp (Gigartinales, Rhodophyceae) are common in many high-latitude, shallow benthic marine communities in Antarctica, but previous observations have indicated little or no exploitation by potential herbivores. We have measured retention of test disks over the mouths of the common Antarctic sea urchin Sterechinus neumayeri Meissner, and we have used this assay to examine potential chemical defenses in I. cordata and P. antarctica. Thallus disks of both macroalgal species were retained by the urchins for significantly shorter times than inert filter paper disks and much shorter times than paper disks with a feeding stimulant. Both nonpolar and polar extracts of each macroalgal species added to disks with a feeding stimulant significantly decreased retention times relative to controls. These results support the hypothesis that chemical defenses in I. cordata and P. antarctica play a role in deterring potential herbivores.     

广东中山市薇甘菊地理分布及适生区预测

通过实地踏查，收集薇甘菊(Mikania micrantha)在广东中山市的分布情况，绘制薇甘菊在中山市的分布图，并利用MaxEnt模型，对薇甘菊实际分布点的环境变量进行定量分析，预测出当前气候下薇甘菊在中山市的适生区。结果表明，中山市所辖25个镇(街道)和市自然保护地管护中心均有薇甘菊分布，总体呈南多北少的态势；ROC曲线的AUC值均在0.8以上，预测结果具有较高的可信度；降水量变化方差、海拔、最冷月份最低温度和最暖季降水量为限制薇甘菊在中山市分布的4个最大环境变量，累积贡献率达75.5%；中山市95.40%的地区对薇甘菊的生长具有不同程度的适宜性，其中高、中、低适生区面积分别占中山市面积的5.33%、33.56%、56.51%。综上所述，薇甘菊对中山市的入侵较为严重，扩散趋势未被遏制；MaxEnt模型能较好地预测薇甘菊在中山市的潜在分布区，但是存在一定偏差。     

Assessing the risk of Eccritotarsus eichhorniae to pickerelweed,Pontederia cordata in North America

The mirid Eccritotarsus eichhorniae is a newly described species with potential as a biological control agent for water hyacinth, Eichhornia crassipes, in North America. A series of quarantine-based studies quantified E. eichhorniae usage of Pontederia cordata with no-choice, adult choice, nymph choice, multi-generation, and impact tests. Although greater numbers of E. eichhorniae adults developed on E. crassipes in two separate no-choice trials, some E. eichhorniae were able to complete development on P. cordata in both trials. Adults showed a clear oviposition preference for E. crassipes and F₁ progeny reduced the mean relative growth rate of E. crassipes but not P. cordata. Naïve nymphs were more likely to leave P. cordata for E. crassipes but not all nymphs left P. cordata when given a choice. Both multi-generation trials showed a rapid increase in the density of adults and nymphs on E. crassipes over four to five generations while population densities on P. cordata did not change, indicating that this insect can maintain populations on this plant. The modest damage inflicted by a sibling species on E. crassipes, coupled with the ability of E. eichhorniae to persist on P. cordata, may pose an interpretation challenge to U.S. regulatory agencies concerned with non-target impacts by biological control agents. Another option for the continuing efforts to increase the biological control of E. crassipes is to prioritise the evaluation of other potential agents like Taosa longula Remes Lenicov (Homoptera: Dictopharidae) or Thrypticus truncatus Bickel and Hernández (Diptera: Dolichopodidae) over E. eichhorniae.