薇甘菊化感物质对土壤氮素矿化的影响及其化感利己作用

【目的】研究入侵植物薇甘菊提取物对土壤氮素矿化的影响及化感利己作用,为薇甘菊通过释放化感物质促进自身生长并排斥本地植物生长提供实验证据,为揭示薇甘菊的入侵机制提供理论依据。【方法】采用经典的化感生测实验、化感物质添加实验以及盆栽控制实验,对比研究薇甘菊及其本地伴生植物水提液和粗提物的化感生测效应、水提液和粗提物添加对土壤氮素的影响以及水提液添加对薇甘菊生长的影响。【结果】与本地伴生种相比,薇甘菊水提液的化感抑制作用较强且促进了土壤硝态氮的生成;而薇甘菊粗提物的化感作用较弱且抑制了土壤铵态氮和硝态氮的生成。水提液盆栽控制实验结果表明,与本地伴生种火炭母相比,薇甘菊水提液具有显著的化感利己作用,这与薇甘菊水提液处理后薇甘菊生长土壤中的蛋白酶活性增强和有效氮含量增加相一致。【结论】薇甘菊可通过水溶性化感物质促进有效氮的生成来实现化感利己作用。     

A native parasitic plant and soil microorganisms facilitate a native plant co‐occurrence with an invasive plant

Invasive plants often interact with antagonists that include native parasitic plants and pathogenic soil microbes, which may reduce fitness of the invaders. However, to date, most of the studies on the ecological consequences of antagonistic interactions between invasive plants and the resident biota focused only on pairwise interactions. A full understanding of invasion dynamics requires studies that test the effects of multiple antagonists on fitness of invasive plants and co‐occurring native plants. Here, we used an invasive plant Mikania micrantha, a co‐occurring native plant Coix lacryma‐jobi, and a native holoparasitic plant Cuscuta campestris to test whether parasitism on M. micrantha interacts with soil fungi and bacteria to reduce fitness of the invader and promote growth of the co‐occurring native plant. In a factorial setup, M. micrantha and C. lacryma‐jobi were grown together in pots in the presence versus absence of parasitism on M. micrantha by C. campestris and in the presence versus absence of full complements of soil bacteria and fungi. Fungicide and bactericide were used to suppress soil fungi and bacteria, respectively. Findings show that heavy parasitism by C. campestris caused the greatest reduction in M. micrantha biomass when soil fungi and bacteria were suppressed. In contrast, the co‐occurring native plant C. lacryma‐jobi experienced the greatest increase in biomass when grown with heavily parasitized M. micrantha and in the presence of a full complement of soil fungi and bacteria. Taken together, our results suggest that selective parasitism on susceptible invasive plants by native parasitic plants and soil microorganisms may diminish competitive ability of invasive plants and facilitate native plant coexistence with invasive plants.     

果园转型生态公益林防控薇甘菊的生态改造

【背景】深圳大面积果园已转型为生态公益林,但果树被入侵的薇甘菊攀爬覆盖,严重地段已导致群落退行性演替,问题亟待解决。【方法】选取有多种生境的转型果园,分片区开展以植树为核心的生态改造试验,树种以种植后不进行人工除草抚育的血桐、幌伞枫、阴香为主,辅以提高物种多样性为目标的演替中后期树种,均采用袋装大苗于2011年5月种植。【结果】在树冠连续、郁闭的果林片区,所植苗木死亡,林下草本稀少,始终无薇甘菊。在其他非郁闭片区,血桐与幌伞枫生长良好且从未被覆盖;阴香虽于秋冬季被全覆盖但不死亡,次年春新枝穿透覆盖层正常生长;其余种苗木对薇甘菊处于劣势。【结论与意义】郁闭度高的果林片区林下光照弱,能阻止薇甘菊定居,无需人工干预;血桐和幌伞枫分别具抗/耐受薇甘菊覆盖的特性,种后均无需抚育;其余树种则需抚育。因此,掌握各个树种的特性,适地种植、按需精准定株抚育是转型果园低成本、技术简单、一劳永逸地防控薇甘菊生态改造的精髓。在应对有害藤本危害时,勿忽略筛选出不惧该藤本的植物种的可能,在不使用农药、无有效动物或微生物天敌的情况下,它们有可能成为生态安全的防控改造树种。     

从种内、种间化感作用分析入侵种薇甘菊及其近邻种的非协同进化趋势

为预测入侵植物与其邻近物种间的非协同进化趋势,分别提取薇甘菊(Mikania micrantha)及其近邻种五爪金龙(Ipomoea cairica)、葛藤(Pueraria lobata)和鸡矢藤(Paederia scandens)的叶片水提液处理幼苗,对薇甘菊及其近邻种的种内、种间化感作用进行研究。结果表明,薇甘菊对3种近邻种的化感作用呈现不同趋势(SE=0.50, 0.61,–0.16),但种内存在较强的化感促进作用(SE=0.61),说明其种内化感竞争较弱;葛藤的种内化感促进作用(SE=0.32)弱于薇甘菊,种间的化感促进作用与薇甘菊相似(SE=0.52, 0.50);五爪金龙种内化感促进作用(SE=0.06)弱于薇甘菊和葛藤(SE=0.32),种间促进作用(SE=0.24)弱于薇甘菊(SE=0.61);鸡矢藤的种内、种间化感作用均表现为抑制作用(SE=–0.18,–0.07),说明种内、种间化感竞争较强。野外调查表明4种植物分布的频度和多度均表现为薇甘菊葛藤五爪金龙鸡矢藤,这与化感竞争力结果一致。可见,种内与种间化感作用在入侵植物与近邻植物的综合竞争力中扮演着极为重要的作用,这为入侵种与近邻种之间的非协同进化趋势指明了方向。     

基于无人机高光谱影像的薇甘菊分布提取研究——以云南德宏州为例

为有效控制薇甘菊入侵,及时掌握其空间分布和动态变化,基于无人机高光谱数据,通过深度学习（DL）、支持向量机（SVM）、随机森林（RF）等方法提取云南省德宏州微甘菊分布情况。结果表明,DL、SVM和RF等3种方法均有效实现了薇甘菊的分布提取,以DL方法的提取效果最佳,制图精度和用户精度分别为96.61%和95.00%;其次为RF方法,制图精度和用户精度分别为94.83%和91.67%;SVM方法的制图精度和用户精度分别为92.45%和81.67%。这3种方法均能很好提取薇甘菊集中分布区域,且DL和RF方法对零散分布薇甘菊的识别效果优于SVM。因此,无人机高光谱影像为薇甘菊的监测、预警和精准防治提供了支撑和依据,对保护当地生态系统安全具有重要意义。     

Climbing capacity of the invasive vine Mikania micrantha Kunth on vertical artificial poles

Climbing capacity of invasive climbers is an important parameter to evaluate in the species invasive potential and processes in forests. However, this feature has not attracted the attention of invasion biologists. In the present study, we assessed the climbing traits and capacity of Mikania micrantha; a herbaceous invasive stem-twiner by supplying artificial vertical supports of different sizes ranging from 1.0 to 8.0 cm in diameter. We also calculated the theoretical maximum usable host size of a M. micrantha shoot based on confirm of the hypothesis that curvature of M. micrantha shoots will remain constant and not affected by support pole size. A total 164-tested M. micrantha shoots ascended the supports successfully. Shoot success rate declined significantly when support diameter exceeded 5.0 cm. The largest pole M. micrantha ascended successfully was 6.6 cm, while the theoretical value is 7.5 cm on average. Curvature declined significantly with increasing shoot diameter. However, no significant correlation was detected between curvature and support diameter, and most M. micrantha shoots maintained relatively constant curvature within a small fluctuation range (0.1–0.2 cm^?1) near the average value (0.16 cm^?1). We compared our results with the only two similar studies available, and concluded that climbing shoot ascent angle on supports decreased with increasing support diameter, while curvature remained constant, which was not affected by support size. These appear to be common attributes for herbaceous stem-twiners. Maximum usable host size was an important factor for successful M. micrantha ascent. We recommend this as a vital criterion in species management.     

我国入侵植物薇甘菊(菊科)的细胞学研究

为了解入侵植物薇甘菊(Mikania micrantha)的细胞学特性,研究了薇甘菊在我国广东东南部4居群和台湾2居群的染色体数目和染色体形态。结果表明,所有居群的薇甘菊染色体数目均为2n=36,第一对染色体为近中部着丝粒染色体,其长臂中部具有次缢痕,显著大于其余染色体。广东深圳大学和深圳水库居群的核型公式为2n=20m+14sm+2st;广东汕头、阳江和台湾屏东居群为2n=22m+12sm+2st;台湾宜兰居群为2n=18m+16sm+2st。此前有报道薇甘菊深圳大学居群的染色体数目为2n=38,推断为制片过程中第一对染色体从次缢痕处断裂而导致的计数错误。因此,薇甘菊虽存在非整倍性和多倍性变化,但在广东东南部和台湾的入侵居群中目前仅发现基于x=18的二倍体(2n=36),该种在这些地区的成功入侵与多倍性无关。