Traits explain invasion of alien plants into tropical rainforests

• 1. The establishment of new botanic gardens in tropical regions highlights a need for weed risk assessment tools suitable for tropical ecosystems. The relevance of plant traits for invasion into tropical rainforests has not been well studied.
• 2. Working in and around four botanic gardens in Indonesia where 590 alien species have been planted, we estimated the effect of four plant traits, plus time since species introduction, on: (a) the naturalization probability and (b) abundance (density) of naturalized species in adjacent native tropical rainforests; and (c) the distance that naturalized alien plants have spread from the botanic gardens.
• 3. We found that specific leaf area (SLA) strongly differentiated 23 naturalized from 78 non‐naturalized alien species (randomly selected from 577 non‐naturalized species) in our study. These trends may indicate that aliens with high SLA, which had a higher probability of naturalization, benefit from at least two factors when establishing in tropical forests: high growth rates and occupation of forest gaps. Naturalized aliens had high SLA and tended to be short. However, plant height was not significantly related to species'' naturalization probability when considered alongside other traits.
• 4. Alien species that were present in the gardens for over 30 years and those with small seeds also had higher probabilities of becoming naturalized, indicating that garden plants can invade the understorey of closed canopy tropical rainforests, especially when invading species are shade tolerant and have sufficient time to establish.
• 5. On average, alien species that were not animal dispersed spread 78 m further into the forests and were more likely to naturalize than animal‐dispersed species. We did not detect relationships between the measured traits and estimated density of naturalized aliens in the adjacent forests.
• 6. Synthesis: Traits were able to differentiate alien species from botanic gardens that naturalized in native forest from those that did not; this is promising for developing trait‐based risk assessment in the tropics. To limit the risk of invasion and spread into adjacent native forests, we suggest tropical botanic gardens avoid planting alien species with fast carbon capture strategies and those that are shade tolerant.

     

草地利用方式对温性典型草原优势种植物功能性状的影响

当外界环境发生变化后植物能够改变自身功能性状及时调整适应策略, 因此植物功能性状能够有效地反映植物对草地利用变化的响应, 然而在内蒙古草原从植物功能性状角度开展草地利用方式影响的研究略少。该研究以内蒙古典型草原大针茅(Stipa grandis)、羊草(Leymus chinensis)、糙隐子草(Cleistogenes squarrosa)和冷蒿(Artemisia frigida) 4种主要优势种为研究对象, 探讨在长期自由放牧、割草、短期围封和长期无干扰的影响下优势种植物功能性状的差异, 以期从功能性状视角, 揭示植物在受到外界干扰后的适应策略, 旨为天然草地的可持续管理提供基础数据支持和科学依据。结果表明: 1)除糙隐子草外, 在长期放牧后内蒙古典型草原优势植物植株高度、根长和植物碳氮含量降低, 这些性状的变化能够使植物个体小型化, 适口性降低, 表明植物通过逃避放牧的策略适应长期自由放牧的干扰; 在割草管理方式下, 优势种的高度和比叶面积有增加的趋势, 其中冷蒿的氮含量对割草响应最敏感, 其根、茎、叶中的氮含量均在割草样地最低; 围封和长期无干扰处理下植物的碳氮含量增加, 表明在干扰强度降低后, 植物通过功能性状的改变从资源获取策略向资源储藏策略转变。2)对优势种功能性状集合分析表明, 糙隐子草具有较低的植株高度和较高的比叶面积, 冷蒿具有较高的木质素含量和氮含量, 这些性状能够使两种植物被家畜采食量减少, 并保证其具有较强的再生能力, 这可能是糙隐子草和冷蒿耐牧的原因; 大针茅具有最高的植株高度、最大的叶片干物质含量, 以及最高的茎、叶纤维素含量, 说明大针茅是非常典型的竞争物种, 在干扰较低的条件下, 大针茅采取竞争策略对其他物种产生较大的竞争压力可能是其占优势的重要原因。     

Ecological effects of cell-level processes: genome size,functional traits and regional abundance of herbaceous plant species

Background and Aims

Genome size is known to be correlated with a number of phenotypic traits associated with cell sizes and cell-division rates. Genome size was therefore used as a proxy for them in order to assess how common plant traits such as height, specific leaf area and seed size/number predict species regional abundance. In this study it is hypothesized that if there is residual correlation between genome size and abundance after these traits are partialled out, there must be additional ecological effects of cell size and/or cell-division rate.

Methods

Variation in genome size, plant traits and regional abundance were examined in 436 herbaceous species of central European flora, and relationships were sought for among these variables by correlation and path analysis.

Key Results

Species regional abundance was weakly but significantly correlated with genome size; the relationship was stronger for annuals (R² = 0·145) than for perennials (R² = 0·027). In annuals, genome size was linked to abundance via its effect on seed size, which constrains seed number and hence population growth rate. In perennials, it weakly affected (via height and specific leaf area) competitive ability. These relationships did not change qualitatively after phylogenetic correction. In both annuals and perennials there was an unresolved effect of genome size on abundance.

Conclusions

The findings indicate that additional predictors of regional abundance should be sought among variables that are linked to cell size and cell-division rate. Signals of these cell-level processes remain identifiable even at the landscape scale, and show deep differences between perennials and annuals. Plant population biology could thus possibly benefit from more systematic use of indicators of cell-level processes.     

The global invasion success of Central European plants is related to distribution characteristics in their native range and species traits

Aim Determining which traits predispose a species to become invasive is a fundamental question of invasion ecology, but traits affect invasiveness in concert with other factors that need to be controlled for. Here, we explore the relative effects of biological traits of plant species and their distributional characteristics in the native range on invasion success at two stages of invasion. Location Czech Republic (for native species); and the world (for alien species). Methods The source pool of 1218 species of seed plants native to Central Europe was derived from the flora of the Czech Republic, and their occurrence in 706 alien floras all over the world was recorded, distinguishing whether they were listed as an ‘alien’ or a ‘weed’ in the latest version of Randall’s ‘Global compendium of weeds’ database. The latter type of occurrence was considered to indicate species ability to invade and cause economic impact, i.e. a more advanced stage of invasion. Using the statistical technique of regression trees, we tested whether 19 biological traits and five distributional characteristics of the species in their native range can be used to predict species success in two stages of invasion. Results The probability of a species becoming alien outside its native distribution range is determined by the size of its native range, and its tolerance of a wide range of climates acquired in the region of origin. Biological traits play only an indirect role at this stage of invasion via determining the size of the native range. However, the ability of species to become a weed is determined not only by the above characteristics of native distribution, but also directly by biological traits (life form and strategy, early flowering, tall stature, generative reproduction, number of ploidy levels and opportunistic dispersal by a number of vectors). Species phylogenetic relatedness plays only a minor role; it is more important at the lowest taxonomic levels and at the later stage of invasion. Main conclusion The global success of Central European species as ‘weeds’ is determined by their distributional characteristics in the native ranges and by biological traits, but the relative importance of these determinants depends on the stage of invasion. Species which have large native ranges and are common within these ranges should be paid increased attention upon introductions, and the above biological traits should be taken into account in screening systems applied to evaluate deliberate introductions of alien plants to new regions.     

Species abundance is jointly determined by functional traits and negative density dependence in a subtropical forest in southern China

植物物种多度受功能性状和负密度依赖共同影响——以中国南亚热带黑石顶森林样地为例 影响植物群落中植物物种多度的因素较多,确定关键影响因素及阐明其具体机制一直是群落生态学的研究重点之一。目前确定性的影响因素主要有两大类：植物功能性状和负密度依赖。功能性状通过影响植物的竞争能力、资源的获取效率、对环境的适应能力等方面进而影响植物的多度;负密度依赖表现在同种或异种植物个体在空间上聚集,特异性的寄主(病原菌、昆虫等)传播容易导致植物个体(主要为幼苗和小树)死亡,种群发生自疏,进而影响植物的多度。到目前为止,单一探究植物功能性状或负密度依赖对植物多度影响机制的研究已有大量报道,而将两者结合来探讨对植物多度的影响的工作相对较少。为了更深入地探索影响植物多度的机制,本研究中我们综合分析了功能性状与负密度依赖对植物多度的影响。研究地点为广东省黑石顶亚热带森林50 ha大样地;功能性状方面选取了叶面积(LA)、比叶面 积(SLA)、叶片干物质含量(LDMC)、叶片氮含量(LNC)和最大电子传输速率(ETR_max);植物物种所受负密度依赖强度通过构建小树在样地两次普查期间的存活状况受邻体密度影响的层次贝叶斯模型计算;通过结构方程模型构建功能性状-负密度依赖-物种多度的内在联系框架。结构方程模型结果显示,物种多度受功能性状和负密度依赖共同作用,其中功能性状对物种多度的影响包括直接作用和通过负密度依赖的间接作用。具体来说,SLA对多度的影响包括直接和间接两种;LDMC和LNC仅间接影响物种多度;LA和ETR_max对多度只有直接影响;负密度依赖与物种多度之间存在直接的负相关关系,说明多度较高的物种受到的负密度依赖效应更强。结构方程模型对物种多度差异的解释度达到20%。以上结果表明,黑石顶植物多度分布是功能性状与负密度依赖共同作用的结果;比叶面积在所研究的因素中贡献最大。该项工作有助于提高我们对亚热带森林植物常见种和稀有种分布格局的理解。     

Shifts in fine root traits within and among species along a fine-scale hydrological gradient

Background and AimsLessons from above-ground trait ecology and resource economics theory may not be directly translatable to below-ground traits due to differences in function, trade-offs and environmental constraints. Here we examine root functional traits within and across species along a fine-scale hydrological gradient. We ask two related questions: (1) What is the relative magnitude of trait variation across the gradient for within- versus among-species variation? (2) Do correlations among below-ground plant traits conform with predictions from resource-economic spectrum theory?MethodsWe sampled four below-ground fine-root traits (specific root length, branching intensity, root tissue density and root dry matter content) and four above-ground traits (specific leaf area, leaf size, plant height and leaf dry matter content) in vascular plants along a fine-scale hydrological gradient within a wet heathland community in south-eastern Australia. Below-ground and above-ground traits were sampled both within and among species.Key ResultsRoot traits shifted both within and among species across the hydrological gradient. Within- and among-species patterns for root tissue density showed similar declines towards the wetter end of the gradient. Other root traits showed a variety of patterns with respect to within- and among-species variation. Filtering of species has a stronger effect compared with the average within-species shift: the slopes of the relationships between soil moisture and traits were steeper across species than slopes of within species. Between species, below-ground traits were only weakly linked to each other and to above-ground traits, but these weak links did in some cases correspond with predictions from economic theory.ConclusionsOne of the challenges of research on root traits has been considerable intraspecific variation. Here we show that part of intraspecific root trait variation is structured by a fine-scale hydrological gradient, and that the variation aligns with among-species trends in some cases. Patterns in root tissue density are especially intriguing and may play an important role in species and individual response to moisture conditions. Given the importance of roots in the uptake of resources, and in carbon and nutrient turnover, it is vital that we establish patterns of root trait variation across environmental gradients.     

桂西南喀斯特地区优势木本经济植物叶功能性状变异及其适应策略

植物叶功能性状可直接或间接地反映植物对环境变化的响应与适应策略.该文采用野外气体交换测量和实验室分析相结合的方法,以桂西南典型喀斯特灌丛常见种龙须藤和黄荆为对照,对该区域5种优势木本经济植物的叶功能性状指标及其关系进行研究.结果表明:(1)11个叶功能性状指标种内均存在不同程度的变异,除胞间CO2浓度和水分利用效率外,...     

Contribution of above- and below-ground plant traits to the structure and function of grassland soil microbial communities

Background and Aims

Abiotic properties of soil are known to be major drivers of the microbial community within it. Our understanding of how soil microbial properties are related to the functional structure and diversity of plant communities, however, is limited and largely restricted to above-ground plant traits, with the role of below-ground traits being poorly understood. This study investigated the relative contributions of soil abiotic properties and plant traits, both above-ground and below-ground, to variations in microbial processes involved in grassland nitrogen turnover.

Methods

In mountain grasslands distributed across three European sites, a correlative approach was used to examine the role of a large range of plant functional traits and soil abiotic factors on microbial variables, including gene abundance of nitrifiers and denitrifiers and their potential activities.

Key Results

Direct effects of soil abiotic parameters were found to have the most significant influence on the microbial groups investigated. Indirect pathways via plant functional traits contributed substantially to explaining the relative abundance of fungi and bacteria and gene abundances of the investigated microbial communities, while they explained little of the variance in microbial activities. Gene abundances of nitrifiers and denitrifiers were most strongly related to below-ground plant traits, suggesting that they were the most relevant traits for explaining variation in community structure and abundances of soil microbes involved in nitrification and denitrification.

Conclusions

The results suggest that consideration of plant traits, and especially below-ground traits, increases our ability to describe variation in the abundances and the functional characteristics of microbial communities in grassland soils.     

Plant functional traits explain interspecific differences in immediate cyclone damage to trees of an endangered rainforest community in north Queensland

Abstract Cyclones cause profound immediate impacts on tropical rainforest trees, including defoliation, limb loss, snapping of stems and uprooting. Some studies have shown that plant functional traits such as tree size, buttress roots and wood density are correlated with these forms of cyclone damage. On 20 March 2006, Severe Tropical Cyclone Larry crossed the north Queensland coast and proceeded inland across the Atherton Tablelands, impacting the critically endangered Mabi Type 5b rainforest. We investigated the effects of Cyclone Larry on common tree species by categorizing damage to trees as uprooted, snapped, limbs damaged (light, moderate, severe) or upright and estimating levels of defoliation. Damage was then related to functional traits including tree size, presence of buttress roots, wood density, and leaf size and strength. Levels of damage differed between species. Tree size (diameter at breast height) and the presence of buttress roots were not related to damage levels. Wood density was significantly negatively correlated to proportion of trees with snapped stems and significantly positively correlated with the proportion of trees upright with no or light limb damage. Levels of defoliation were significantly related to leaf strength (specific leaf area – SLA) and to leaf width, but not other components of leaf size (area or length) or petiole length. Species with high wood density and low SLA (e.g. Argyrodendron spp.) were found to have high cyclone resistance, the ability to resist damage, while species with low wood density and high SLA (e.g. Dendrocnide photinophylla) exhibited low resistance. However, traits related to low resistance are also those linked to rapid growth and high cyclone resilience, the ability to recover from damage, so it is unlikely that the Mabi forest will experience long‐term changes in floristic composition following Cyclone Larry.     

温带草地主要优势植物不同器官间功能性状的关联

理解植物各器官间功能性状的关联, 有助于确定控制功能性状的内在机制以及性状间的比例关系。基于内蒙古温带草地19个地点、42种优势草本植物的野外观测, 分析了叶片、茎、生殖器官、细根和粗根间功能性状(N、P含量、N:P、比叶面积、比根长以及叶片和细根的组织密度)的关联。主要结果如下: 在种群和物种水平上, 各器官的N和P含量都显著正相关, 比叶面积与叶片N、P含量和组织密度在种群水平上显著负相关, 而在物种水平上没有显著的相关关系; 而比根长仅在种群水平上与细根的组织密度显著负相关。N、P含量以及N:P在各器官之间一致呈显著正相关, 而比叶面积和比根长没有显著的相关关系。叶片和细根的组织密度在种群水平上显著负相关, 而在物种水平上没有显著的相关关系。非禾草比禾草相应器官(除茎外)的N、P含量高, 但二者茎的N、P含量没有显著的差异; 豆科植物比非豆科植物相应器官的N含量高, 而P含量没有显著的差异。     

柴达木盆地荒漠植物功能性状及其对环境因子的响应

植物功能性状是植物适应环境的外在表达,反映了植物在不同环境中的生存策略,探究干旱区荒漠植物功能性状及其与环境之间的关系,有助于理解植物适应极端干旱环境的生态对策,为保护荒漠地区生态系统提供理论依据。以柴达木盆地为研究区,选取8个植物功能性状指标,包含4种植物生活型,10种荒漠植物,探究荒漠植物功能性状的基本特征及其对环境因子的响应。研究表明：柴达木盆地植物叶片碳含量(LCC)、叶片氮含量(LNC)、叶片磷含量(LPC)、叶片C∶N、叶片N∶P、叶片稳定碳同位素(Leafδ¹³C)、叶片干物质含量(LDMC)和植株高度(Height)的变化范围分别为272.07—466.00mg/g、12.40—44.50mg/g、0.51—2.07mg/g、8.62—29.74、11.37—39.29、-27.38‰—-14.80‰、100—480mg/g、3.00—264.22cm。不同生活型间LNC、LPC、叶片N∶P和LDMC差异不显著,LCC、叶片C∶N、叶片δ¹³C和植株高度存在显著差异。LNC、LPC和叶片N∶P与全球、中国和青藏高原相比不存在显...     

沙质草地植物功能性状对放牧、增水、氮添加及其耦合效应的响应机制

人类活动和气候变化对陆地生态系统结构和功能的影响日益明显。在中国半干旱草原区,植物功能性状对这些变化的响应机制仍不是很清楚。以科尔沁沙质草地植物群落功能性状（CWM_trait）、一年生和多年生植物平均功能性状为研究对象,开展非生长季放牧、增水、氮添加及其耦合效应的模拟控制试验,于2016年8月中旬在沙质草地开展了植物功能性状的调查及测定,主要包括植物高度、比叶面积（specific leaf area,SLA）、叶片干物质含量（leaf dry matter content,LDMC）、叶片氮含量（leaf nitrogen content,LNC）和叶片碳同位素（leaf carbon isotopes,δ¹³C）。结果表明：氮添加显著提高了CWM_height和CWM_LNC（P<0.05）,降低了CWM_LDMC（P<0.05）,同时放牧和增水的耦合效应对CWM_SLA具有显著影响（P<0.05）;放牧显著降低了一年生植物的平均高度（P<0.05）,氮添加显著提高了一年生植物的平均高度、LNC和δ¹³C （P<0.05）;氮添加显著提高了多年生植物的平均SLA、LNC和δ¹³C （P<0.05）,同时放牧和增水的耦合效应对多年生植物的平均SLA和LDMC具有显著影响（P<0.05）。主成分分析表明,放牧促进了植物群落和多年生植物SLA与LDMC、LNC和δ¹³C之间的负相关关系,增水促进了植物群落和多年生植物高度与SLA之间的正相关关系以及LDMC、LNC和δ¹³C之间的正相关关系,说明多年生植物在调控沙质草地植物群落响应外界干扰时具有较强的主导性作用。非生长季放牧、生长季禁牧有利于沙质草地的可持续发展和管理,增水能够减缓放牧压力对于草地植物的影响,氮添加有利于植物同化δ¹³C,并提高植物叶片的水分利用效率。     

环境因子对海岛植物茎、叶功能性状的影响

植物功能性状与环境之间的关系是功能性状研究的重点,海岛作为独特的生态系统,其植物功能性状必然和大陆存在差异。为了明确海岛植被的生态适应机制,该文以平潭岛森林群落为研究对象,通过测定茎、叶10个功能性状,以及地形和土壤9个环境因子,探讨了植物功能性状之间的权衡关系,分析了环境因子对海岛植物功能性状的影响。结果表明:(1)比叶面积(SLA)与叶氮含量(LNC)、叶磷含量(LPC)呈正相关,与叶厚度(LT)、叶干物质含量(LDMC)、茎组织密度(STD)、叶碳含量(LCC)呈负相关; LDMC与LNC、茎氮含量(SNC)呈负相关; LT与STD呈正相关,与LNC和LPC呈负相关; LPC与LNC、SNC呈正相关;茎和叶C、N含量均呈正相关。(2)土壤有机质和TN是海岛植物功能性状的主要土壤影响因子。然而,由于土壤中磷含量的缺乏,LNC、茎磷含量(SPC)、SNC均与土壤全磷呈正相关; LDMC与土壤全氮呈正相关;STD与土壤有机质呈正相关; SLA随着土壤pH的增加而增加。(3)坡位和坡度是海岛植物功能性状的主要地形影响因子。SLA、SPC随着海拔上升而下降; STD、LDMC随着海拔和坡度增大而增大; LNC、LPC阴坡大于阳坡。该研究为海岛植被修复和重建提供了参考依据。     

黄土丘陵区植物叶片与细根功能性状关系及其变化

通过植物叶片功能性状(比叶面积、叶组织密度、叶氮含量)和细根功能性状(比根长、根组织密度、根氮含量)间的相互关系,分析植物对环境的适应途径;然后根据性状间的差异进行了层次聚类,将物种划分为3大功能型,并分析了不同功能型对环境的适应策略.结果表明:黄土丘陵区延河流域149种植物的叶氮含量与比叶面积和根氮含量正相关、与叶组织密度负相关,比根长与根组织密度负相关,除了根氮含量,其余根性状与叶性状不相关.此外,功能性状间关系变化和适应策略在不同功能型之间也存在差异.功能型1的植物具有最强的耐旱力和防御力;功能型3的植物具有最强的养分维持能力用以对抗营养贫瘠的环境;功能型2的植物居中,生长速率最高,具有较强的竞争力、分布最广;根据C-S-R理论,功能型1和3属于“胁迫忍耐型”策略(S策略),功能型2则属于“竞争型”(C)和“干扰型”(R)策略的综合.研究结果为黄土丘陵区植被恢复规划及物种配置等提供依据.     

Seedling traits, plasticity and local differentiation as strategies of invasive species of Impatiens in central Europe

Background and Aims

Invasiveness of some alien plants is associated with their traits, plastic responses to environmental conditions and interpopulation differentiation. To obtain insights into the role of these processes in contributing to variation in performance, we compared congeneric species of Impatiens (Balsaminaceae) with different origin and invasion status that occur in central Europe.

Methods

Native I. noli-tangere and three alien species (highly invasive I. glandulifera, less invasive I. parviflora and potentially invasive I. capensis) were studied and their responses to simulated canopy shading and different nutrient and moisture levels were determined in terms of survival and seedling traits.

Key Results and Conclusions

Impatiens glandulifera produced high biomass in all the treatments and the control, exhibiting the ‘Jack-and-master’ strategy that makes it a strong competitor from germination onwards. The results suggest that plasticity and differentiation occurred in all the species tested and that along the continuum from plasticity to differentiation, the species at the plasticity end is the better invader. The most invasive species I. glandulifera appears to be highly plastic, whereas the other two less invasive species, I. parviflora and I. capensis, exhibited lower plasticity but rather strong population differentiation. The invasive Impatiens species were taller and exhibited higher plasticity and differentiation than native I. noli-tangere. This suggests that even within one genus, the relative importance of the phenomena contributing to invasiveness appears to be species''specific.