外来树种生物入侵研究现状与进展

外来树种如果形成生物入侵,对生态系统会产生多方面影响,其中最严重的是对入侵地生物多样性和生态系统功能的影响.生物入侵造成的危害具有爆发性和长期性,且不可逆转.与其他种类的生物相比,外来树种的入侵具有很长的时滞,预测比较困难.我国引种的外来树种数量多,过去对外来树种的生物入侵研究很少,开展外来树种入侵性评价和生态风险评估,制定统一的技术规程和标准,确定各种外来树种的入侵性等级,对我国林业经济和生态环境建设具有重要价值和意义.我国在外来树种生物入侵方面的研究起步较晚,建立外来树种信息系统,加强信息交流与共享,制定外来树种入侵评价标准与风险评估体系,研究建立外来树种监测及生物入侵早期预警系统是未来的研究重点.正确处理林木引种与生物入侵的相互关系,对外来树种进行生物入侵风险评估,制定生物入侵防范战略,可以有效地防止生物入侵的发生.同时也要针对树木的生命周期长、具有重要利用价值的特点,避免夸大外来树种的生物入侵风险,更好地促进外来树种事业的发展.     

湖北省外来树种调查与入侵风险评价

基于文献资料和野外调查数据,分析湖北省外来树种的种类组成、分布状况和原产地信息,按照《外来树种对自然生态系统入侵风险评价技术规程》中的方法对湖北省外来树种进行入侵风险等级划分及评价。结果表明：①湖北省目前共有外来树种74种,隶属31科53属,其中豆科最多,有15种,松科次之的,有14种;乔木有49种,占总种数的66.22%,灌木有22种,占29.73%,木质藤本有3种,占4.05%。②全省各地均有外来树种分布,其中武汉市外来树种种类最多,有61种,其次为宜昌市有36种。③根据来源地分析,起源于北美洲的最多,有35种,占总数的47.30%,其次为亚洲,有17种,占22.97%。④入侵风险等级评价结果为低风险的树种有62种,中风险的树种有12种,未发现有高风险的树种。     

外来有害生物红火蚁入侵勐腊县的风险评估

红火蚁是一种重大危险性入侵害虫,被列为我国林业检疫性害虫。2013年在云南省局部地区发现红火蚁,2014年7月入侵到云南省勐腊县。为防止红火蚁在勐腊县及邻近地区进一步扩散蔓延,运用云南外来入侵有害生物多指标综合评价体系评估红火蚁在勐腊县的风险。结果表明,勐腊县红火蚁的综合风险性R值为2.44,风险评估等级为高度危险,该虫在勐腊县有定殖并大范围扩散的潜在风险。     

黄山市外来入侵植物分析

通过对黄山市外来植物的调查和整理分析,报道了81种外来植物,并且从入侵植物本身进行了分析,以期为外来植物预警系统的建设和对黄山的生物多样性保护提供科学依据。研究结果表明:(1)来源地评价:来自热带美洲的外来植物容易成为入侵种类并造成较大危害;(2)分类学评价:有菊科、苋科、蝶形花科具有较强的入侵能力和扩散能力,在引种这些植物种类时尤其要注意;(3)生长型评价:草本具有较强的入侵能力,藤本植物、灌木入侵能力小,造成的危害程度也较小;(4)入侵植物本身特性如繁殖能力、繁殖方式、传播特性和生存能力等决定其入侵能力。     

外来植物种对鼎湖山自然保护区的入侵及其影响

对鼎湖山自然保护区外来植物入侵的监测和研究表明，鼎湖山的外来维管植物占所有维管植物种类的比例已达23％。外来植物入侵程度在保护区不同功能区内差异明显，进一步证明人为干扰是影响外来种入侵的主要因素。自然保护区内外来种入侵的来源主要是人工引入，少量自然侵入者也与人为干扰有关。生态系统的结构越复杂，生物多样性水平愈高，生态系统的可入侵性愈低，反之可入侵性越高。入侵性外来种通过影响生态系统的环境因子，破坏生态系统功能，同时亦干扰破坏群落原有种的生理活动和过程，成为植物杀手，从而降低群落的物种多样性。文内还提出了在自然保护区防止外来种入侵的对策和措施。     

浅议外来植物入侵的途径、机理和危害

对外来植物入侵的途径、机理和危害进行了综述与分析。外来植物入侵受多种因素影响,可分为自然因素和人为因素两类。主要从生态幅、繁殖特性、竞争力、遗传变异特性等方面分析了外来植物入侵的机理。外来植物入侵的危害主要体现在影响当地生态系统的结构和功能、土壤的理化性质、气候、生物多样性、改变物种进化方向和人类的生产与生活等方面。     

舟山岛外来植物及其入侵性分析

为防控外来植物的扩散入侵,于2012年4月—2013年4月共5次全面调查了舟山岛及其附近岛屿的植物种类组成和外来植物分布状况,同时辅以典型抽样法,并结合历史资料,归纳整理了舟山岛不同历史时期的外来植物名录,共计48科106属145种;在此基础上对外来植物进行了风险评估并探讨了部分重要物种的入侵性。其中加拿大一枝黄花(Solidago canadensis Linn.)、喜旱莲子草(Alternanthera philoxeroides(Mart.)Griseb.)对舟山岛入侵危害最大,应为今后防治的重点;藿香蓟(Ageratum conyzoides Sieber ex Steud.)、豚草(Ambrosia artemisiifolia Linn.)等著名外来恶性杂草近20 a来并没有明显的扩散,危害等级为中等;新记录外来植物野莴苣(Lactuca serriola Linn.)的扩散、危害风险值得关注和警惕;水生生境外来植物中,凤眼蓝(Eichhornia crassipes(Mart.)Solms)风险等级低,而互花米草(Spartina alterniflora Hubb.)、大米草(S.anglica Lois.)风险等级高,应加强监控;栽培植物西欧蝇子草(Silene gallica Linn.)首现逸为野生,生长扩散需要跟踪监控。     

广西红树林主要外来植物现状及防控对策研究

通过查阅文献资料、访问调查、实地踏查及座谈的方式,对广西红树林主要三种外来植物互花米草、无瓣海桑、拉关木引种历史、资源现状、防控措施进行调查,并分析其生态安全性和社会影响。互花米草是确定的入侵种;无瓣海桑、拉关木能够在非种植区域实现自然扩散,能够快速占领宜林地甚至进入本土红树植物群落内部,表现出了一定的入侵性。针对外来植物监测、防控过程中存在的诸多制约因素,提出相应的对策。     

黑荆和银荆的繁殖扩散与入侵潜力

对2种典型亚热带外来树种黑荆和银荆林分和单株土壤种子库、幼苗扩散进行调查,依据繁殖体类型、数量和扩散距离预测黑荆和银荆的入侵性.结果表明:黑荆以种子繁殖为主,繁殖体数量大,银荆以根蘖繁殖为主,繁殖成功率高.黑荆和银荆林分内土壤种子库数量都很大,分别达28 882粒·m-2和1 475粒·m-2;种子主要分布在枯落物中,有利于其继续传播;有活力种子比例高,室内发芽率可达85%以上,树种建群能力强.虽然黑荆和银荆都有大量的繁殖体存在于土壤中,但萌发并存活的幼苗数量相对较少,林缘幼苗数量分别为0.8株·m-2和1.0株·m-2,单株周围幼苗数量分别为1.3株·m-2和0.6株·m-2,树种向外扩散速度慢;黑荆和银荆的自然扩散主要是近距离的扩散,距离约是树高的2倍,黑荆种子扩散方式以豆荚的吸胀和失水作用、重力和风力扩散为主,下风向数量最大,传播距离最远;银荆以根萌蘖扩散为主,没有方向性.以上特点表明,2个树种都具有较高的入侵潜力,在引种栽培时要因地适宜,加强管理,谨防危害当地生态环境.     

红火蚁入侵浙江的风险分析及防控对策

红火蚁Solenopsis invicta为我国检疫性外来入侵有害生物,目前已经在我国12个省份和地区发生和危害,与浙江省相邻的福建和江西也是重要发生疫区,2016年浙江省首次在金华市被发现并得到了有效控制。为了充分认识其在浙江省发生和危害的风险,根据有害生物风险分析(PRA)程序,从传入、定殖和扩散的可能性、危害影响和危害管理难度5个方面进行定性和定量分析,结果表明,浙江省红火蚁的有害生物风险综合评价值R=2.41,为高度风险,应引起高度重视并采取科学的防控措施。     

植物引种与外来物种入侵的探讨

生物入侵正在成为影响我国生态系统的重要因素之一。外来生物入侵的问题 ,越来越受到全社会的关注。本文主要分析了我国外来入侵植物的现状 ,如外来入侵植物的主要种类、对我国生态环境的危害、主要传入途径以及监控措施。     

广州市车陂涌不同土地利用类型草本植物群落特征

通过对广州市车陂涌河岸带人为干扰较少的 5 个河段的草本植物群落特征进行调查,分析河 岸带的物种多样性和影响河岸带植被分布的主要因素,总结适宜广州河岸带生态护岸的草本植物。经统 计,河岸带样方内共有草本植物 57 种,隶属于 23 科 51 属,禾本科与菊科植物最多,分别占 10 种和 8 种。本土植物 47 种,外来入侵植物 10 种,存在外来生物潜在入侵危险。群落结构复杂,物种组成繁多。 结合生态护岸原则和调查结果,最终筛选出节节草 Commelina diffusa、柔枝莠竹 Microstegium vimineum、 红尾翎 Digitaria radicosa 等 10 种本土植物作为生态护岸植物进行推广。     

Conservation of forest biodiversity and ecosystem properties in a pastoral landscape of the Ecuadorian Andes

High Andean cloud forests are home to a diversity of unique wildlife and are important providers of ecosystem services to people in the Andean regions. The extent of these cloud forests has been widely reduced through conversion to pasture for livestock, which threatens the forests’ ability to support biodiversity and provide ecosystem services. This paper explores whether impacts on woody plant biodiversity and four ecosystem properties (woody plant species richness, juvenile timber tree abundance, soil organic matter content and soil moisture) from converting forest to pasture can be mitigated if some woody forest vegetation is maintained within pastures. Woody vegetation in pastures was found to conserve those woody plant species that are more tolerant to exposure and grazing, but conservation of the high montane cloud forest community required areas of forest from which livestock were restricted. The sampled sites clustered according to woody plant species cover; these clusters represented a gradient from pasture with patches of shrubs to mature forest. Clusters differed in both woody plant species richness and number of juvenile timber trees whereas soil organic matter and soil moisture were observed to be similar among all clusters. This suggests that the different habitats may have some equivalent ecosystem properties. We conclude that the presence of woody vegetation in pastures may reduce some of the impacts of converting forest to pasture, but should not be considered a substitute for protecting large areas of forest, which are essential for maintaining woody plant species diversity in high Andean cloud forest.     

乐昌市外来入侵植物调查研究

基于野外考察及相关文献查阅,调查分析了乐昌市现有外来入侵植物的种类组成、生长型、分布生境、入侵范围及危害程度.结果表明:乐昌市2013-2015年共有外来入侵植物104种,隶属于36科,81属.其中菊科(23种)、豆科(14种)、禾本科(8种)和苋科(8种)植物占乐昌市外来入侵植物总种数的50.96％.另外根据生物学与生态学特性、自然地理分布、入侵范围及其所产生的危害,将乐昌市外来入侵种划分为5级:即恶性入侵类(1级,14种)、严重入侵类(2级,13种)、局部入侵类(3级,38种)、一般入侵类(4级,18种)和有待观察类(5级,21种).与周边其他地区外来入侵植物相比发现,乐昌市与香港地区共有种数最多,为72种;广州市与乐昌市共有种数百分比最大,为69.86％.     

外来入侵种对我国园林绿地的危害及防治措施

在分析外来入侵种对城市绿地危害的基础上, 提出防治外来入侵种对园林绿地危害的具体措施:降低现有外来入侵种对城市园林绿地的危害; 严格控制引进外来入侵种; 加强科学研究, 采取综合防范措施; 建立健全外来物种风险评估制度。     

云南湿地外来入侵植物特征研究

通过对云南湿地外来入侵植物的实地调查,确定云南湿地外来入侵植物共有70种,隶属于24科54属;来源于5大洲,其中来源于美洲的植物种类最多,共47种,占67.1％;入侵途径以人为传入为主,占95.7％。按水分生态类型分,以中生植物为主;按生活型分,以草本为主;按繁殖方式分,以种子繁殖为主,但以无性繁殖为主的入侵物种扩散速度快,危害性大。外来入侵植物在云南省16个地州（市）129个县（区）的湿地均有分布,其中全省范围分布的有43种,占61.5％。     

Singular and interactive effects of blowdown, salvage logging, and wildfire in sub-boreal pine systems

The role of disturbance in structuring vegetation is widely recognized; however, we are only beginning to understand the effects of multiple interacting disturbances on ecosystem recovery and development. Of particular interest is the impact of post-disturbance management interventions, particularly in light of the global controversy surrounding the effects of salvage logging on forest ecosystem recovery. Studies of salvage logging impacts have focused on the effects of post-disturbance salvage logging within the context of a single natural disturbance event. There have been no formal evaluations of how these effects may differ when followed in short sequence by a second, high severity natural disturbance. To evaluate the impact of this management practice within the context of multiple disturbances, we examined the structural and woody plant community responses of sub-boreal Pinus banksiana systems to a rapid sequence of disturbances. Specifically, we compared responses to Blowdown (B), Fire (F), Blowdown-Fire, and Blowdown-Salvage-Fire (BSF) and compared these to undisturbed control (C) stands. Comparisons between BF and BSF indicated that the primary effect of salvage logging was a decrease in the abundance of structural legacies, such as downed woody debris and snags. Both of these compound disturbance sequences (BF and BSF), resulted in similar woody plant communities, largely dominated by Populus tremuloides; however, there was greater homogeneity in community composition in salvage logged areas. Areas experiencing solely fire (F stands) were dominated by P. banksiana regeneration, and blowdown areas (B stands) were largely characterized by regeneration from shade tolerant conifer species. Our results suggest that salvage logging impacts on woody plant communities are diminished when followed by a second high severity disturbance; however, impacts on structural legacies persist. Provisions for the retention of snags, downed logs, and surviving trees as part of salvage logging operations will minimize these structural impacts and may allow for greater ecosystem recovery following these disturbance combinations.     

GROWING EUCALYPTUS SALIGNA

SYNOPSIS

Monitoring plots were established in two mountain catchment areas in the Western Cape to assess the impacts of dense alien plant stands and alien plant clearance on indigenous Fynbos vegetation. In both areas Pinus pinaster was the dominant alien species with Hakea sericea also common. Indigenous vegetation persisted in the understorey of invaded stands, indicating that the high density of aliens was of recent development. Species richness of indigenous vegetation was lower in invaded, compared to uninvaded plots.

After clearance by felling and burning, the aliens were effectively controlled, except for pines at Genadendal, where unfelled, older generation pines released seeds to recruit in the post-fire environment. The post-fire recovery of indigenous vegetation at both sites was rapid, with no significant differences measured in projected canopy cover, plant density and functional guild richness between invaded and uninvaded control plots. This improved condition of the indigenous vegetation was reflected in an increase in community similarity between invaded and uninvaded plots after fire. However, species richness and diversity remained lower for invaded plots compared to controls two and a half years post-fire and guild structure also differed between treatments.

Clearance of serotinous alien species by felling and burning is an effective method for controlling the aliens and initiating Fynbos recovery in relatively young vegetation (8 years in this study). It is recommended that alien clearance teams are coordinated to reduce time lags between the clearance of younger generation aliens and older established or inaccessible trees. Biological control should be developed, where not already available, to lower the re-invasion risk from clearance escapes. At sites where soil damage may result from fire through heavy slash (e.g, older vegetation), steps should be taken to minimize this risk and contingency plans developed to prevent soil erosion and accelerate post-fire vegetation recovery.     

重庆地区常绿岩垂草引种生物入侵风险评价

为了防控引种可能带来的危害,对已引物种应进行生态入侵风险评估,建立相应监控对策。笔者通过查阅资料、实地调研、专家咨询等方法,应用外来种入侵的风险评估体系及风险评价标准,对重庆地区常绿岩垂草引种生物入侵的风险性进行了分析,结论为:在重庆地区,常绿岩垂草属于具有一定风险的外来种,需要进一步地获取相关信息或采取防范监控措施。