Priority effects—the phenomenon where early-arriving species influence the establishment, growth, and reproduction of later-arriving species during community assembly—play a critical role in determining the invasion success of exotic species. However, how priority effects are influenced by nitrogen (N) availability remains understudied. The invasive species Bidens frondosa has rapidly expanded its range in China over the past few years. Yet it remains unclear how priority effects in B. frondosa versus native species may mediate invasion success, as well as how nutrient levels may alter these effects. Addressing these questions is essential for understanding the mechanisms driving B. frondosa invasion and for developing effective management strategies. In a greenhouse experiment, we manipulated the planting order of B. frondosa and its native congener B. biternata, then measured the growth and competitiveness of B. frondosa and B. biternata in both control and N addition treatments. Planting order greatly impacted the growth and competitiveness of both B. frondosa and B. biternata. Early arrival had more positive effects on B. frondosa than B. biternata, while late arrival more strongly inhibited B. frondosa than B. biternata. For B. frondosa, priority effects lessened with nitrogen addition, but the opposite occurred for B. biternata. Thus, priority effects may favor B. frondosa invasion, while late arrival, particularly under nitrogen addition, may curb its spread. As such, sowing early-germinating native species represents a useful management strategy for controlling B. frondosa invasions.

外来入侵植物威胁生物多样性,造成巨大的生态和经济损失.近10多年来,广西新归化植物和外来入侵植物种类日益增多,分布范围不断扩大,对广西生物多样性和生态安全的影响日益严重.本文介绍了广西外来入侵植物发生的原因、基本特点、发展趋势、对生物多样性和农林牧渔各产业等的影响以及各专家学者对广西外来入侵植物的研究进展,探讨了广西外来入侵植物防控存在的问题和挑战,并提出了一些基本的防控措施建议,为更好地实施国家近年来发布的《中华人民共和国生物安全法》等提供基本依据.

【Aim】 Several studies have shown that alien invasive plants have serious negative impacts on biodiversity, especially on native species that compete for similar resources. Global nitrogen（N） deposition can increase soil N availability, which may favor fast-growing invasive plants. However, whether invasive plants are superior to their native congeners, and whether the competitive relationship between them will be altered with increased N deposition remain unclear. Understanding these questions will help to predict alien plant invasion risks and protect native biodiversity under N deposition. 【Method】 We conducted a greenhouse experiment, in which invasive species Bidens pilosa and its native congener B. biternata were grown alone and together under three N addition treatments(CK: 0 g·m -2 ·a -1 , low N addition: 1 g·m -2 ·a -1 and high N addition: 5 g·m -2 ·a -1 ). We compared the growth（plant height, branch number, root/shoot ratio and biomass） and competition [relative dominance index（RDI） and relative interaction index（RII）] parameters of the invasive species and its native congener. 【Result】 High level N addition significantly increased the biomass and decreased the root/shoot ratio of invasive B. pilosa regardless of whether it was grown alone or grown together with B. biternata, and also enhanced the plant height and branch number of B. pilosa when grown alone. But high level N addition only enhanced the biomass of native B. biternata when grown alone. The RDI and RII of B. pilosa were greater than that of B. biternata under all N treatments. Furthermore, high level N addition significantly increased the RDI of B. pilosa whereas reduced the RDI and RII of the native congener. The RII of B. pilosa did not significantly differ among N treatments.【Conclusion】 High level N is more favorable for the growth of B. pilosa than for that of B. biternata. The invasive species exhibit stronger competitive ability and more tolerance than its native congener under all N treatments, and the competitive ability was magnified under high N level. Global N deposition may exacerbate the competition inhibition of B. pilosa over its native congener and hence increase its invasion risk.

为探讨微地形(Microtopography)对茶条木(Delavaya toxocarpa)种子和幼苗分布格局的影响,采用样方法对广西平果市龙何喀斯特生态重建示范区茶条木群落中不同微地形的茶条木种子密度、种子存活率、幼苗密度和幼苗年龄结构等进行研究.结果表明:茶条木群落中的微地形有石面、小平地、石沟、石窝和石缝等5种,各微地形的茶条木平均种子密度、平均种子存活率和平均幼苗密度分别为4.97-212.28粒/m2、35.7%-76.5%和0.09-44.85株/m2,石面的平均种子密度和平均幼苗密度显著小于其他4种微地形(P<0.05),平均种子存活率显著小于小平地、石沟和石窝;茶条木1年生、2年生和3年生以上的幼苗占比分别为84.44%-100.00%、0.00%-15.38%和0.00%-2.22%,3年生以上幼苗的总存活率不足1.0%.综上,在桂西南石漠化山区茶条木群落中,茶条木的种子密度、种子存活率和幼苗密度等受微地形的影响明显,多年生幼苗存活率低,林下更新能力差,其群落管理可采取冠层疏枝和林隙除杂等措施改善微环境,促进幼苗生长和种群更新.

为筛选替代控制紫茎泽兰的本地植物及探讨提高替代控制效率的方法,通过盆栽实验并利用相对产量(RY)和竞争攻击力系数(A)衡量了 3种本地植物与紫茎泽兰的竞争关系,同时评估了活性炭(AC)、杀真菌剂(FC)和二者联合(AC+FC)对它们竞争的影响.结果表明:(1)不添加任何物质条件下:紫茎泽兰与南酸枣混种时,紫茎泽兰的生物量明显高于单种(P＜0.05),其 RY和A分别显著大于1和0(P＜0.05);紫茎泽兰分别与假地豆和狗尾草混种时,紫茎泽兰的株高和生物量均明显低于单种(P＜0.05),其RY和A均分别显著小于1和0(P＜0.05).说明紫茎泽兰的竞争力强于南酸枣而弱于假地豆和狗尾草,假地豆和狗尾草可以在一定区域作为替代控制紫茎泽兰的潜在目标植物.(2)与不添加任何物质相比,紫茎泽兰与南酸枣混种时,AC、FC及AC+FC处理增加了紫茎泽兰的根冠比,降低了其地上生物量比,也降低了南酸枣的生物量(P＜0.05);紫茎泽兰与假地豆混种时,AC和AC+FC处理增加了假地豆的株高和生物量,FC处理增加了紫茎泽兰的株高(P＜0.05);紫茎泽兰与狗尾草混种时,AC和AC+FC处理增加了紫茎泽兰的根冠比、降低了其地上生物量比(P＜0.05),FC处理对两种植物的各生长变量均无明显影响(P＞0.05).说明在紫茎泽兰与不同植物竞争时,添加活性炭和杀真菌剂对每种植物的影响作用不同.添加活性炭或杀真菌剂是否能提高本地植物替代控制紫茎泽兰的效率还需要根据具体的目标物种来确定.

Nitrogen (N) deposition, precipitation and their interaction affect plant invasions in temperate ecosystems with limiting N and water resources, but whether and how they affect plant invasions in subtropical native communities with abundant N and precipitation remains unclear. We constructed in situ artificial communities with 12 common native plant species in a subtropical system and introduced four common invasive plant species and their native counterparts to these communities. We compared plant growth and establishment of introduced invasive species and native counterparts in communities exposed to ambient (CK), N addition (N+), increased precipitation (P+) and N addition plus increased precipitation (P+N+). We also investigated the density and aboveground biomass of communities under such conditions. P+ alone did not enhance the performance of invasive species or native counterparts. N+ enhanced only the aboveground biomass and relative density of invasive species. P+N+ enhanced the growth and establishment performance of both invasive species and native counterparts. Most growth and establishment parameters of invasive species were greater than those of native counterparts under N+, P+ and P+N+ conditions. The density and aboveground biomass of native communities established by invasive species were significantly lower than those of native communities established by native counterparts under P+N+ conditions. These results suggest that P+ may magnify the effects of N+ on performance of invasive species in subtropical native communities where N and water are often abundant, which may help to understand the effect of global change on plant invasion in subtropical ecosystems.

了解养分增加对入侵植物生长和竞争的影响以及不同入侵种群对养分变化响应的差异 有助于预测入侵植物的入侵风险。为探讨大狼耙草的入侵风险，该文通过同质种植园实验， 研究了不同养分水平下大狼耙草河北、江苏、江西和广西四个入侵种群在单种和各种群与近 缘本地植物金盏银盘混种时的生长和竞争响应。结果表明：(1) 单种时四个种群的株高、分枝 数和总生物量在高养分下显著高于低养分下，繁殖比在低养分下显著高于高养分下(江苏种群 除外)；混种时四个种群各生长参数的竞争响应在高养分下小于低养分下。(2) 各养分下，广 西和江西种群的株高和总生物量显著高于河北种群，广西种群的分枝数最多(低、中和高养分 下分别为12±0.86、16.83±0.95 和21.83±1.14)；河北种群的繁殖比在低养分[(47.33±3.29)%] 和高养分[(25.74±2.82)%]下最高，且显著高于同养分下的广西种群[低养分为(30.92± 1.78)%和高养分为(19.77±1.22)%]。中养分下，河北种群总生物量的竞争响应(-0.51±0.04) 显著大于广西种群(-0.35±0.06)，繁殖生物量的竞争响应(-0.46±0.03)也显著大于广西种群 (-0.28±0.07)。以上结果说明了高养分提高大狼耙草的生长和竞争能力；并且，生长和竞争能 力在种群间有差异。养分增加和入侵种群间基因流可能会潜在地提高大狼耙草的入侵风险。

以广西平果市龙何喀斯特生态重建示范区为背景,比较其自然封育区不同类型微地形的形态特征、土壤理化性质及潺槁木姜子〔Litsea glutinosa(Lour.)C.B.Rob.〕叶片性状.结果表明:桂西南喀斯特石漠化山地微地形主要有石面、土面、石沟、石窝和石缝5种类型,面积占比的平均值分别为59.3％、24.1％、9.6％、6.3％和0.7％;同一类型不同单元的长度、宽度和面积变异较大.石沟、石窝和石缝的土壤含水量显著(P<0.05)高于土面和石面;土面土壤容重显著大于石窝和石沟,最大持水量、田间持水量、毛管持水量、毛管孔隙度、非毛管孔隙度和总孔隙度显著小于石窝和石沟,pH值及有机质、全N、全P、全K、全Ca和全Mg含量均最低;石缝土壤pH值及有机质、全P、全Ca和全Mg含量最高,石面土壤全N和全K含量最高.石沟中潺槁木姜子单叶面积和单叶干质量显著大于土面、石窝和石缝,石缝中潺槁木姜子比叶质量显著大于石窝和石沟,土面中潺槁木姜子叶片全C和全Mg含量最高,石沟中潺槁木姜子叶片全N、全P、全K和全Ca含量最高.综合分析结果显示:受不同类型微地形的形态结构和土壤组成的影响,桂西南喀斯特石漠化山地的土壤理化性质和潺槁木姜子叶片性状具有较为明显的微地形分异特征,在该区植被修复中,应根据不同类型微地形的土壤环境特点有针对性地采取自然封育和人工促进修复等措施.

Mile-a-minute (Mikania micrantha Kunth) is a tropical American species and has become a worldwide invasive weed. It was first introduced to mainland China in 1983 in Yingjiang City, Dehong State, Yunnan Province. To assess the origins of populations from Dehong State, Yunnan Province, the genetic structure of 427 individuals from 11 M. micrantha populations from Yunnan, Guangxi, Hainan, and Guangdong provinces were analyzed. A total of 28 alleles were detected in 12 nuclear microsatellite loci. Genetic diversity at the population level was relatively high. An analysis of molecular variance showed that most of the variation occurred within populations (82.73%), and only 18.27% occurred among populations. The genetic differentiation coefficient (F-ST) was 0.183. The estimated gene flow (N-m) from F-ST was 1.116. The independent origins of four populations collected from Dehong State, Yunnan Province, was determined by the unweighted pair-group method with arithmetic means clustering and STRUCTURE analysis. Three gene clusters and one admixture gene cluster were found. A Mantel test of pairwise Nei's genetic distances and pairwise geographic distances revealed no evidence for isolation by distance (r = 0.068, P = 0.343). These results suggest that the post-introduction admixture caused by multiple introductions and high gene flow might contribute to the evolutionary adaptation of M. micrantha. These results could provide a scientific basis for the management of invasive M. micrantha.

On the basis of a brief discussion of the definitions of alien plants, we summarized the investigation and research status of China's naturalized alien plants, and made corrections of the data regarding naturalized alien plants on two papers in 2019 and 2021.

为探讨本地物种假地豆和白饭树对入侵植物飞机草的替代控制潜力,利用培养皿法和同质园种植实验分别研究了两个本地物种种子萌发对飞机草的化感耐受性及其与飞机草的竞争关系。结果显示:除了假地豆的萌发率在高浓度（2.5%）的飞机草叶提取液下受到显著抑制外,两个本地种的萌发在不同浓度飞机草根、茎、叶提取液下均不受抑制。飞机草与假地豆混种时,飞机草的株高、地下生物量比及根冠比显著降低,假地豆的株高无显著变化,但生物量显著增加;飞机草的竞争参数相对产量（RY）显著小于1,竞争攻击力系数显著小于零,表明其竞争力弱于假地豆。飞机草与白饭树混种时,飞机草的根冠比也显著降低,但株高和生物量均显著增加,而白饭树的株高和生物量却显著降低;飞机草的相对产量（RY）显著大于1,竞争攻击力系数显著大于零,表明其竞争力强于白饭树。结合以上结果,本地植物假地豆可以一定程度上竞争抑制飞机草的生长,具有替代控制飞机草的潜力,而白饭树可以在清除飞机草后的入侵地辅助植被修复。实验结果为飞机草替代控制的目标物种的筛选提供了科学依据,对被飞机草入侵生境生物多样性的恢复和重建具有一定指导意义。

Although information on the reproductive biology of the endangered plant family Gesneriaceae is well known, the pollination mechanisms of these plants in karst regions are poorly understood. This study demonstrated the flowering phenology, pollinators, and breeding system of Hemiboea ovalifolia in karst regions. Findings revealed that the anthesis of H. ovalifolia often occurred late, during sunset, or early morning, with duration of 2-4 days; there was a certain level of temporal overlap between pollen viability and stigma receptivity; the most effective pollinators were Bombus ignitus and Anthophora zonata. Controlled pollination indicated that these plants were pollen limited and exhibited late-acting inbreeding depression resulting from the seed sets; there were significant differences in fruit sets between open-pollination and self-pollination or cross pollination, and in seed sets between self-pollination and cross-pollination or open-pollination. Despite the co-existence of large numbers of fruit and seed sets, and vegetative propagation in H. ovalifolia, a failure in seedling survival, and long duration to establishing first-year seedlings in natural populations suggests that the species does not easily recover from damage.

[目的]广西中越边境是中国通往东盟各国的重要通道.近年来,外来入侵植物对该地区的生态安全和经济发展都产生了严重的威胁.为有效预防和控制中越边境的外来入侵植物,保障中越边境地区生态安全和经济健康发展,需要掌握中越边境外来入侵植物的基本信息.[方法]通过实地调查、拍照和采集标本,分析广西中越边境外来入侵植物的种类组成、生活型和危害程度等;通过文献资料,了解所调查外来入侵植物的原产地和入侵途径等.[结果]广西中越边境外来入侵植物共121种,隶属于38科,其中菊科最多,有26种,豆科次之,有11种;外来入侵植物以草本为主,有102种,占总种数的84.30％;原产地来源最多的是美洲,有92种,占总种数的68.66％;人为有意引入有68种,占总种数的56.20％;严重危害的有23种,中等危害的有32种,一般危害的有66种.[结论]广西中越边境外来入侵植物种类多且分布范围广、传播途径复杂、危害严重种类多,急需对广西中越边境的外来入侵植物进行预防和控制,特别是要严密监控新发生入侵种类的动态,积极控制已产生危害的严重种类,实行预防为主、防治结合的原则.

BACKGROUND AND AIMSThe strengths of biotic interactions such as herbivory are expected to decrease with increasing latitude for native species. To what extent this applies to invasive species and what the consequences of this variation are for competition among native and invasive species remain unexplored. Here, herbivore impacts on the invasive plant Alternanthera philoxeroides and its competition with the native congener A. sessilis were estimated across latitudes in China.METHODSAn experiment in common gardens spanning ten latitudinal degrees was conducted to test how herbivore impacts on A. philoxeroides, A. sessilis and competition between them change with latitude. In addition, a field survey was conducted from 21 °N to 36.8 °N to test whether A. philoxeroides invasiveness changes with latitude in nature as a result of variations in herbivory.KEY RESULTSIn the experiment, A. sessilis cover was significantly higher than A. philoxeroides cover when they competed in the absence of herbivores but otherwise their cover was comparable. But, A. philoxeroides cover was always higher on average than A. sessilis cover at middle latitude. At high latitude, only A. sessilis emerged in the second year. Herbivore abundance decreased with latitude and A. philoxeroides emerged earlier than A. sessilis at middle latitude. In the field survey, the ratio of A. philoxeroides to A. sessilis cover was hump-shaped with latitude.CONCLUSIONThese results indicate that herbivory may promote A. philoxeroides invasion only at low latitude by altering the outcome of competition in favour of the invader and points to the importance of other factors, such as earlier emergence, in A. philoxeroides invasion at higher latitudes. These results suggest that the key factors promoting plant invasions might change with latitude, highlighting the importance of teasing apart the roles of multiple factors in plant invasions within a bio-geographic framework.

Crofton weed is a major invasive species in China. It exhibits superior growth characteristics and can outcompete with native species via allolepathic effects and modulation of the soil fungal microbiome. The simple removal of invading plants will not ensure restoration of the habitat due to the persistence of allelochemicals and viable seeds in the surrounding soil. An orthogonal experimental design was employed to evaluate the effects of three control factors (A, powdered natural inhibitor species to retard growth; B, activated charcoal to absorb allelochemicals; and C, fungicide to reduce fungal modulation effects), applied at three levels, on the growth and competitive ability of Crofton weed against two native species, in a pot‐culture experiment. All treatments reduced all measured growth parameters (P < 0.05) except for a specific leaf area, when compared with control plants. Furthermore, the competitive capacity of Crofton weed was decreased in the treatments while that of the native species was improved. Application to soil of the powdered natural inhibitor species and of activated charcoal significantly inhibited plant growth and competitive ability of Crofton weed (P < 0.05). Application of fungicide was less effective, but significantly reduced the specific leaf area of Crofton weed plants (P < 0.05). The specific combination of factors producing the greatest decrease in plant growth and competitive ability (compared with the control) included the addition of Delavaya toxocarpa powder (37.5 g per kg soil), addition of activated charcoal to soil at a ratio of 1:3 (v/v) (62.5 g per kg soil), and application of fungicide (Thiophanate‐Methyl) (0.28 g per kg soil).

本研究从入侵性、适应性、扩散性和危害性4个准则层及其22个指标层分析了飞机草的入侵风险,并运用风险评估的方法对其生态风险进行初步研究,提出了飞机草风险评估体系以及判断标准,其结果表明:飞机草的综合风险指数为74.5,属于高风险外来植物,应严格禁止在我国各地区之间的引入.

To explore the traits related to the invasiveness of exotic Bidens species in China,we compared the morphology,growth,biomass allocation,photosynthesis,and phenotypic plasticity of two invasive Bidens species (B.pilosa and B.frondosa) with two native congeners (B.biternata and B.tripartita) under different light and water conditions in a common garden.The results showed that the invasive and native species displayed similar plant heights and total biomass under unfavorable conditions (i.e.low light and low water treatment).However,under favorable light and water conditions (i.e.high light and high water treatment),the invasive species showed significantly greater plant height and total biomass than the native congeners.Furthermore,in high light treatments,the relative growth rate of the invasive species was higher than that of the native species.The invasive species allocated more resources to root biomass at high light levels compared to low light levels,while they allocated more resources to leaf biomass at low light levels compared to high light levels.Specific leaf area of the invasive species was greater than that of the native congeners under low light conditions.These traits may enhance the abilities of invasive species to capture and utilize resources,enabling them to withstand adverse environmental conditions or to respond more positively to favorable conditions.The phenotypic plasticity indices of invasive and native species for morphology,growth,and photosynthetic parameters were low for water availability and high for light intensity.However,for most variables,invasive species showed a higher phenotypic plasticity index than native congeners,and this may contribute to their invasion success.In addition,there were no significant differences for photosynthetic parameters between invasive and native Bidens species under any treatment.In conclusion,this study shows that morphology,growth,biomass allocation,and phenotypic plasticity may play more important roles than photosynthetic parameters in the success of invasive Bidens species.

The ecological strategies of Ageratina adenophora in four communities growing in different habitats in Guangxi were investigated by studying plant growth and reproduction. Most growth and reproduction characters significantly var-ied among communities. Except for plant height,the other parameters of A. adenophora were highest in open terrain and lowest in a Quercus fabri-Dalbergia hupeana mixed forest. There were significant differences of aboveground biomass and reproductive allocation among different communities of A. adenophora. The aboveground biomass of A. adenophora in open terrain and eucalyptus forest were significant greater than in the other two communities. The reproductive allo-cation of A. adenophora in open terrain was maximum and significantly greater than in the other communities. There was a significant negative correlation between canopy density of communities and growth and reproduction parameters of A. adenophora,which showed that the canopy density of communities affected the growth and reproduction of A. adeno-phora. A. adenophora exhibited different adaptation strategies according to the different environments suggesting that it has a strong adaptability and thus easily invading vari-ous habitats. However,the community with high canopy density had a good control effect on A. adenophora. Therefore,rebuilding community and increasing canopy density can effectively control A. adenophora.

Bidens frondosa is a new invasive species in China. However, the mechanisms underlying its invasiveness are still not understood. This study compared the new invader with its invasive congener, Bidens pilosa, and two native congeners, Bidens biternata and Bidens tripartita, in terms of their morphology, growth, biomass allocation and photosynthetic parameters across variant light and water conditions, aiming to explore the traits that are associated with the invasiveness of the invasive species. All these species are annual herbs. The results showed that the four congeners had a similar tendency of plasticity in their morphological and growth traits to varying light and water, but their response was quantitatively different. Most of the morphological and growing variables, as well as the photosynthetic parameters, were affected more strongly by manipulated light levels. Although B. frondosa had a lower total biomass and relative growth rate than the invasive congener, B. pilosa, the trait values related to growth (e.g. plant height, total biomass, relative growth rate and specific leaf area) and the mean value of the plasticity index were higher for the invasive B. frondosa than for the native B. tripartita. These could contribute to the invasiveness of the invasive species. In addition, the native species, B. biternata, is a vigorous weed with a strong adaptive capacity across various light and water gradients, suggesting that it has the potential to be invasive if introduced into areas with suitable conditions for growth.

Three species of naturalized plants were reported as new records to Guangxi of China,i.e.Amaranthus palmeri,Ipomoea hederifolia and Paspalum wettsteinii.Amaranthus palmeri is an unconsciously introduced exotic species,which was listed in the fourth batch of exotic invasive plants in China by the Ministry of Environmental Protection of the People's Republic of China and Chinese Academy of Sciences in 2016.Ipomoea hederifolia and Paspalum wettsteinii are deliberately introduced exotic species,and established in natural habitats and may become potential invasive plants.The distribution,growth characteristics and propagation properties of the three exotic species were introduced;their spread and invasiveness were also analyzed and discussed in this article.The discovery for the three naturalized plants in natural habitats provides information for prevention and controlling invasive plants in Guangxi.