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1.
Insect herbivores can become extensive invaders if they are able to undergo host expansions onto widely-grown agricultural host plants. An important yet unresolved question is whether all herbivore populations are equally able to utilize new host plants or if populations may be geographically structured, that is only a subset has the potential to undergo a host range expansion and become widely invasive. We examined if derived and ancestral geographic populations of L. decemlineata or Colorado potato beetle, varied in host preference and performance on both wild (Solanum rostratum) and cultivated (Solanum tuberosum) host plants. Sampling from six different North American regions (3 ancestral and 2 derived), we performed two full-factorial experiments to test for differences in host preference, acceptance, and performance on S. rostraum and S. tuberosum. Our results reveal the development of new (cultivated) host associations within pest populations of L. decemlineata following its geographic expansion. Pest beetles (i.e., Vermont populations) discriminated less between host plants and grew faster than all other beetle population on both host species. The Vermont beetles also developed faster on leaves than all other populations. The greater general preference, acceptance, and performance of Vermont beetles on all host types underscores the virulence of the pest form of the beetle and may help to explain the absence of pest incidence within the ancestral regions of L. decemlineata.  相似文献   

2.
In The Netherlands, insect pests on trees and shrubs are being monitored continuously since 1946. During these years, almost all insect pest populations showed marked changes, which may be the result of changes in forest management, shifts in forest composition, climate change and the arrival of new pests from the Mediterranean region or from other continents. In order to generate hypothesis about possible relationships between species ecology and environmental factors, we have analyzed 61 years of population development of the 98 most abundant species in the database while paying attention to life history traits and preferred host plants. The 22 species with infestations lasting a few years only were excluded from the analysis. Of the remaining 76 species, 18 were present over the entire observation period of 61 years. Of the other species, 27 showed a decline and 31 showed an increase. On coniferous trees most species showed decreasing populations. Increasing populations were found most on deciduous trees. Not directly climate-related factors such as changes in forest age, tree composition and forest management were identified as the most important causes for the fluctuations in pest insect populations. Climate change is a possible driver of the population increase in Thaumetopoea processionea, Haematoloma dorsatum and of the population decrease in Euproctis chrysorrhoea. The recently increasing exotic species Eupulvinaria hydrangeae and Pulvinaria regalis were exclusively found on trees in cities, presumably in relation to the higher temperatures of the urban habitat.  相似文献   

3.
The utilization of olfactory responses of predators and ­parasitoids to the allelochemicals emitted by phytophagous arthropods and their host plants is becoming more important in biological pest control. The effects of three weed ­species, i.?e. wormwood Artemisia vulgaris L., tansy Tanacetum vulgare L. and stinging nettle Urtica dioica L., which were planted as accompanying vegetations into a lettuce field, were examined for the predatory species Coccinella septempunctata L., Adalia bipunctata (L.), Propylea quatuordecimpunctata (L.) (Coleoptera, Coccinellidae) and Chrysoperla carnea (Steph.) (Neuroptera, Chrysopidae), as well as for aphids during the summer of 2000. The presence of weeds significantly increased the density of adults and larvae of the predators on the lettuce plants in relation to the control (lettuce field without weeds). However, the differences remained smaller for eggs and pupae. C. septempunctata tended to be the most abundant species, followed by P. quatuordecimpunctata. Remarkable differences among the attractiveness levels of the weeds in the 3 treatments were not observed. The increased populations of predators were accompanied by significantly reduced infestation rates with aphids in the treatments in relation to the control. Myzus persicae Sulzer was in general the most abundant aphid species followed by Nasonovia ribisnigri Mosley and Macrosiphum euphorbiae Thomas. The results of the present study are discussed with respect to the management of agroecosystems and the use of weeds in biological control.  相似文献   

4.
Liana habitat and host preferences in northern temperate forests   总被引：1，自引：0，他引：1  
Lianas and other climbers are important ecological and structural components of forest communities. Like other plants, their abundance in a given habitat depends on a variety of factors, such as light, soil moisture and nutrients. However, since lianas require external support, host tree characteristics also influence their distribution. Lianas are conspicuous life forms in tropical regions, but in temperate areas, where they are less prominent, little is known about factors that control their distributions in these forests. We surveyed the climbing plant species in 20 mature (100 years and greater) forested habitats in the Midwest USA at a variety of levels from simple presence/absence, to ground layer abundances, to those species that had ascended trees. We also examined attributes of the tree species with climbers attached to them. Using cluster analysis, we distinguished five different tree communities in our survey locations. We determined that 25% of the trees we surveyed had one or more lianas attached to it, with Parthenocissus quinquefolia (Virginia creeper) the most common climbing species encountered. Canopy cover and soil attributes both influenced climber species presence/absence and ground layer climber abundance. The proportion of liana species of a given climbing type (roots, stem twiner, tendril climber) was significantly related to the DBH of the host tree, with more root climbers and fewer stem and tendril climbers on large trees. In general, the DBH of climbing lianas had a significant positive relationship to the DBH of the host tree; however this varied by the identity of the liana and the tree species. The greater the DBH of the host tree, the higher the probability that it was colonized by one or more lianas, with tree species such as Pinus banksiana (jack pine) and Quercus alba (white oak) being more susceptible to liana colonization than others. Finally, some liana species such as Celastrus scandens (American bittersweet) showed a preference for certain tree species (i.e., P. banksiana) as hosts. The information obtained about the relationship between the tree and climber community in this study provides insight into some of the factors that influence liana distributions in understudied temperate forest habitats and how lianas contribute to the structure of these mature forests. In addition, these data can provide a point of comparison to other liana communities in both temperate and tropical regions.  相似文献   

5.
Host selection is central to understanding the evolution of the interaction between herbivorous insects and host plants. Most studies on host selection of herbivorous insects are focused on the optimal oviposition theory which posits that the herbivores preferentially oviposit on plants that provide optimal conditions for offspring development (preference–performance hypothesis). However, the positive correlation between female oviposition preference and offspring performance is not always observed. Here, we determined the relationship between whitefly settling and oviposition preference and nymph performance of B and Q putative species of Bemisia tabaci on three host plants, cotton Gossypium hirsutum L., tomato Lycopersicum esculentum Mill, and poinsettia Euphorbia pulcherrima Wild. We further investigated whether nutritional and defensive chemistry of the three host species shaped whitefly settling and oviposition preference of both putative species. Foliar chemistry differed significantly among the three host species. Compared to cotton and tomato foliage, poinsettia foliage was 8?% lower in nitrogen, 60?% higher in carbohydrate, and 90?% higher in phenolic compounds, respectively. When given a choice, B and Q putative species of B. tabaci preferred settling on nutritionally superior tomato, whereas both putative species preferentially oviposited on nutritionally inferior poinsettia. Nymph survivorship of B and Q putative species was substantially reduced and nymph developmental duration (egg-to-adult) was markedly prolonged on poinsettia relative to those reared on cotton and tomato. Therefore, our results are consistent with the optimal foraging theory, rather than the optimal oviposition theory. Females of B and Q putative species of B. tabaci preferentially ovipositing on poinsettia may be a trade-off between nymph performance and the avoidance of natural enemy.  相似文献   

6.
The distribution of 17 dominant gall-inducing arthropods and 12 leaf miners on woody plants was analysed in the city of Kiel and surrounding habitats. The number of species and the diversity of the fauna in the two landscapes did not differ very much.Pemphigus bursarius, Schizoneura ulmi undStigmella argentipedella preferred trees in the city. In the city predominated plant parasites that hibernate on their host plant, while species overwintering in the litter on the ground or in the soil were suppressed. Important habitat factors may be mechanical perturbations near the ground (removal of leaf litter, pavement on the ground, trampling, digging of the soil). The number of species declined with decreasing size of the habitat islands (wood — bushes, hedges — individually growing trees or groups of trees on grassland — road trees), the species hibernating in the vegetation layer were favoured.  相似文献   

7.
Tree defoliation by winter moth Operophtera brumata L. (Geometridae, Lepidoptera) caterpillars was quantified in the Białowieża Forest (E Poland) during the recent outbreak (2002). To assess effects of forestry management on defoliation, comparisons were made between mixed species (Tilio–Carpinetum) old-growth stands of natural origin in strictly protected primeval and managed fragments. This forest type was continuous in the primeval part, but highly fragmented in the managed part. The old-growth remnants in the latter part were usually surrounded by younger tree stands (often coniferous plantations). We predicted the winter moth densities would be reduced in fragmented stands due to dispersal mortality incurred by the early stage larvae.As predicted, all species of host trees suffered greater defoliation in the primeval forest. Hornbeam Carpinus betulus L. was the heaviest defoliated host. Other trees, which developed leaves synchronously with hornbeam – maple Acer platanoides L., lime Tilia cordata Mill., and pedunculate oak Quercus robur L. – were strongly affected as well. While we do not show a causal mechanism, greater dispersal mortality in fragmented stands is a most plausible explanation for the observed patterns of defoliation.  相似文献   

8.
Sarta longhorned beetle (SLB), Aeolesthes sarta Solsky, is an economically important pest of fruit and shade trees in central and east Asia. Choice, no-choice, and larval insertion experiments were conducted to determine SLB oviposition preference and larval host suitability on six hardwood tree species including Ulmus carpinifolia Borkh., Ulmus carpinifolia var. umbraculifera Rehd., Platanus orientalis L., Populus alba L., Salix alba L., and Fraxinus rotundifolia Miller subsp. persica (Boiss.), under laboratory conditions. In the choice and no-choice experiments, significantly greater numbers of eggs and living larvae, and greater mass of living larvae were found on U. carpinifolia and U. carpinifolia var. umbraculifera compared to those on the other tree species. In the choice experiment, oviposition did not occur on F. rotundifolia subsp. persica. There were a few eggs on P. alba but no living larvae. The mean mass of living larvae was lowest on P. orientalis. In addition, in the no-choice experiment significantly fewer numbers and mass of living larvae were found in P. alba and F. rotundifolia subsp. persica. In the larval insertion experiment, more larvae survived on U. carpinifolia and U. carpinifolia var. umbraculifera compared to the other trees. Larvae recovered from U. carpinifolia and U. carpinifolia var. umbraculifera weighed significantly more than larvae from the other trees. These results suggest that U. carpinifolia and U. carpinifolia var. umbraculifera are the most preferred and suitable hosts for SLB adults and larvae. Salix alba is an acceptable host for adult oviposition and a potentially suitable host for larval development. Platanus orientalis and P. alba are less suitable, and F. rotundifolia subsp. persica appeared to be unsuitable as a host for SLB.  相似文献   

9.
The main differences betweenThecodiplosis brachyntera (Schwägrichen) andT. japonensis Uchida et Inouye in morphology, bionomics, host plants, ecology, population dynamics, distribution, parasites, economic importance and control methods are given in this paper. The area ofT. b. onPinus sylvestris is more than 10 times larger than that ofP. j. onP. densiflora andP. thunbergii. The flight period of adults and the length of the first instar larvae ofT. b. is about 4 times shorter than those ofT. j. Both species can be transferred (infestation) to otherPinus spp. Death ofPinus trees attacked byT. b. was never observed in Europe. The influence of air pollution may change this situation.T. japonensis caused death ofPinus trees. Thousands of hectares of forests had to be felled. Parasites and predators are important in controlling the population densities of both species, but in practice biological control was only used againstT. j. Studies of chemical contents of needles and larvae produced interesting data on both species.T. brachyntera has been studied for 150 years andT. japonensis for 50 years.  相似文献   

10.
The basidiomycete Laetiporus sulphureus (Bull) Murrill is a forest pathogen causing brown cubical heart rot in a broad range of host trees. Despite its wide distribution and importance, studies aimed at understanding the epidemiology of the fungus in specific areas or hosts are lacking. In this study, an incidence of L. sulphureus as high as 34% was determined through molecular analysis of wood samples collected from 70 carob (Ceratonia siliqua L.) trees in the South‐west of Sicily, Italy. A phylogenetic analysis of Internal Transcribed Spacer (ITS) sequences indicated that all carob isolates belonged to the cluster E of Laetiporus taxonomy. Ten molecular markers based on Single Sequence Repeats (SSRs) designed on the L. sulphureus genome were developed, and isolates were genotyped through High‐resolution Melting (HRM) analysis. High gene diversity (0.581), no correlation between fungal genotype and host tree species and significant correlation between spatial and genetic distance were observed, suggesting an important role of basidiospores in the epidemiology of the fungus and a risk of transmission from a host tree species to the others. Finally, from a prognostic perspective, significant differences among isolates in terms of mycelial growth suggest that in addition to an accurate identification, a phenotypic characterization of isolates affecting trees may also be important.  相似文献   

11.
In most dendrochronological studies, climate-growth relationships are established on dominant trees to minimize non-climatic signals. However, response to environmental factors may be affected by tree-size, which begs the question of the representativeness of dominant trees on the stand level. To highlight the variations in climate-growth relationships among sizes and species, under a wide range of ecological conditions (climate and soil properties), 61 pure even-aged stands were sampled across France. At each stand, two tree-ring chronologies were established from 10 big- to 10 small-diameter trees. Our objectives were, (1) to assess variations in climate sensitivity between the two size-diameter classes, and (2) to investigate the role of species and ecological conditions on these variations. The climate-growth relationships were evaluated from 122 tree-ring chronologies (1 220 trees) through extreme growth years and correlation function analyses. Sensitivity to climate of shade-intolerant and moderately shade-tolerant species (Picea abies (L.) Karst., Pinus sylvestris L. and Quercus petraea (Matt.) Liebl.) remained constant between the size-diameter classes for both temperature and hydric balance, while the shade-tolerant species Abies alba Mill. and Fagus sylvatica L. displayed significant differences, with larger trees being more sensitive to summer drought than smaller trees. This difference increased with increasing climatic xericity. Our results suggest that, for shade-tolerant species, (1) big trees could be more sensitive to climatic change especially under xeric climate, and (2) future tree ring studies should include trees stratified by size to produce unbiased estimation of sensitivity to climate.  相似文献   

12.
Cerambyx welensii Küster is one of the greatest threats to Quercus suber L. and Quercus ilex L. in Spain. Efficient control methods for this species are currently being tested, and the use of traps baited with food-related products for their monitoring and control has been proposed. Cerambyx welensii adults prefer to colonize old or decayed trees, in which cortical exudates frequently release fermentation odors. Fermentation-related compounds, such as ethanol, have been cited as attractants to various hardwood woodborers (as Cerambyx cerdo L.), used either alone or sometimes in combination with other host odors. In this work, we conducted field experiments to ascertain whether chemical blends mimicking fermentation odors were attractive for C. welensii. To this end, we used three types of traps (multiple funnel, cross-vane and single-funnel) baited with six synthetic blends including one or more fermentation-related chemicals (ethanol, ethyl acetate, 3-methyl-1-butanol, acetaldehyde, 2-methyl-1-propanol and 2-methyl-1-butanol), various food-related products (beer, melon and red wine mixed with peach juice) and host monoterpenes (α-pinene, β-pinene, limonene, α-phellandrene and camphene). At high release rates (5–11 g/day), various synthetic blends proved attractive irrespective of trap type. Our results contribute to understand the impact of volatile organic compounds in host selection by woodborers infesting deciduous trees. The results hold promise for optimizing trapping strategies to control C. welensii within an integrated pest management framework.  相似文献   

13.
Norway spruce trees in the subalpine forests of the European Alps are frequently attacked by the needle rust Chrysomyxa rhododendri. The obligate parasite undergoes a complex life cycle with a host shift between rhododendrons (Rhododendron sp.) and Norway spruce [Picea abies (L.) Karsten] and causes a yellowing and defoliation of the current-year needles in summer. Infected trees show several anatomical, morphological and physiological modifications, including a decrease in pigment content and net photosynthesis of infected needles, lower biomass production and reduced radial and height growth. The consequences are diminished timber yield and cripple growth. Because of repeated heavy infections in recent years, forest managers report increasing difficulties in both natural regeneration and afforestation at high elevation sites, where rhododendrons occur. This review gives a summary of the present knowledge about the effects of C. rhododendri infections on Norway spruce, including so far unpublished findings and with particular attention to the phenomena of resistant trees. Implications for subalpine forests and counter strategies are discussed.  相似文献   

14.
Heterobasidion species are the most important pathogens causing root and stem rot on conifers in northern hemisphere forests. The host list of this complex is very wide and includes over 200 species of trees and shrubs. Among the members of this complex, Heterobasidion annosum s. s. has the largest host range. In this study, young plants of Pinus sylvestris, Picea orientalis, Abies nordmanniana, Cedrus libani and Pinus brutia (three different origins) were inoculated on the lower stem with known genets of Heterobasidion annosum s.s. collected from Pinus brutia stands in south-western Türkiye. Infection frequency, assessed as presence of the conidial stage in stem discs following incubation, in the inoculated seedlings was 100%. The Heterobasidion annosum s. s. isolates were re-isolated from all inoculated host species. Control seedlings showed no symptoms of disease. Mortality in inoculated plants was 11.5% of the 735 inoculated plants, which died over an 8-weeks incubation period. The isolates showed greater growth on Cedrus libani, Pinus sylvestris and Picea orientalis seedlings compared to other species tested. On the other hand, it was found that the least affected seedlings were Pinus brutia TB12 and Abies nordmanniana. This study proved that differences occur in aggressiveness of Heterobasidion annosum s. s. to host species. A striking point in the results is that, despite being the host species from which the isolates were obtained, Pinus brutia seedlings showed lower sensitivity to Heterobasidion annosum s. s. than the other conifer species tested. Inoculations of three different Pinus brutia provenances suggested there was no significant difference in mean lesion lengths and fungal growth values in Pinus brutia plants, except in Pinus brutia TB14, which was more susceptible to extension growth of the pathogen.  相似文献   

15.
Evaluation of the harmfulness degree of gall midges (Diptera, Cecidomyiidae) on dominant trees in Eurasia and some taxonomical problems of gall midges on treesAll gall midges species similarly as other insects developing on economically important trees and shrubs are usually designated as pests, as well as in cases if they destroy or damage their host plants or if they were found on their host plant species only several times during the last 150 years. This problem is shown here on gall midges developing on five dominant tree species. Four degree scala was elaborated for evaluation of the degree of harmfulness. The taxonomical problems of the complex of several species of the genus Resseliella and of the species Mikiola orientalis are discussed.

Mit einer Tabelle

Herrn Prof. Dr.W. Schwenke zum 75. Geburtstag am 22. 3. 1996 gewidmet.  相似文献   

16.
The long-term effects of repeated prescribed burning on diameter growth of trees in mixed species dry and wet sclerophyll forest sites in southeast Queensland, Australia were assessed. In addition, fire effects on tree mortality and recruitment in the wet sclerophyll site were evaluated. The results show that growth responses of species to fire were variable. Nevertheless, for most species, recurrent burning had no deleterious effect on tree growth. At the dry sclerophyll site, annual burning since 1952 did not affect growth rates of Eucalyptus drepanophylla and E. acmenoides. On the other hand, E. tereticornis responded positively to annual burning. Smaller Corymbia variegata (formerly Eucalyptus maculata) trees appeared to respond positively to annual burning, while larger trees appeared to respond negatively but this response lessened over time. Periodic burning (every 2–3 years) since 1973 did not significantly affect the growth rates of any tree species. At the wet sclerophyll site, biennial burning since 1972 has enhanced the diameter growth of Lophostemon confertus but depressed that of Syncarpia glomulifera. Quadrennial burning did not affect the diameter growth of L. confertus but depressed that of S. glomulifera. The diameter growth of E. pilularis, C. intermedia, E. microcorys and E. resinifera was not affected by either burning treatment. Basal area growth of most eucalypts at this site was unaffected by burning. However, basal area growth of both S. glomulifera and L. confertus was adversely affected by burning due to tree mortality. For most species, tree mortality was both diameter-dependent and fire-related, that is, smaller trees have a lower chance of survival than larger trees and frequent burning further reduces this probability. Without fire, recruitment was dominated by S. glomulifera and to a lesser extent by L. confertus. Recruitment of these species was adversely affected by burning. This result and the greater mortality of smaller trees with frequent burning suggest that if these trends continue, future stand growth and hence productivity of these species could be jeopardized because of the reduction of the regenerative capacity of the forest. Recruitment was negligible for other tree species in this forest regardless of fire treatment.  相似文献   

17.
Outbreak of the emerging infectious disease sudden oak death continues to threaten California and Oregon forests following introduction of the exotic plant pathogen Phytophthora ramorum. Identifying areas at risk and forecasting changes in forest carbon following disease outbreak requires an understanding of the geographical distribution of host populations, which is unknown. In this study, we quantify and map the population density and carbon contents of five key host species for P. ramorum in California and Oregon, including four hosts killed by the pathogen (Notholithocarpus densiflorus, Quercus agrifolia, Quercus kelloggii and Quercus chrysolepis) and the foliar host Umbellularia californica which supports high sporulation rates. We integrate multiple sources of vegetation data, assembled from sparsely distributed (regional-scale) forest inventory and analysis (FIA) plots and more densely distributed (landscape-scale) plots for monitoring sudden oak death, and develop spatial prediction models based on correlation with environmental variables and spatial dependencies in host abundance. We estimate that 1.8 billion N. densiflorus trees (68 Tg C) and 2.6 billion Quercus host trees (227 Tg C) occur across 3.9 and 17.7 million ha of their respective habitat. A total of 436 million U.californica trees (14 Tg C) occur across 4.2 million ha which frequently overlap with Quercus and N. densiflorus host populations. Combination of landscape-scale data with FIA data resulted in more accurate estimation of host populations and their carbon contents. Forests of northern California and southwest Oregon have the highest concentration of the most susceptible hosts along with climatic conditions that favor pathogen spread. This study represents the first spatially-explicit estimate of P. ramorum host populations and their carbon contents which exceed previously published estimates. Our results will inform landscape- to regional-scale models of disease dynamics and guide management decisions regarding ecosystem impacts including risk of C release following widespread tree mortality.  相似文献   

18.
Drought periods are becoming more extreme worldwide and the ability of plants to contribute towards atmospheric flux is being compromised. Properly functioning stomata provide an exit for water that has been absorbed by the roots, funneled into various cell parts, and eventually released into the atmosphere via transpiration. By observing the effects that weather conditions such as climate change may have on stomatal density, distribution, and functioning, it may be possible to elucidate a portion of the mechanisms trees use to survive longer periods of water stress. This study analyzed stomatal density (SD), stomatal conductance (gs ), CO2 assimilation (A), instantaneous water-use efficiency (WUEi ), and transpiration (E) rates in six native tree species in the Midwestern USA and showed that trees within the same ecotype followed similar trends, but that trees within the same family did not when exposed to identical greenhouse conditions. Naturally drought tolerant tree species demonstrated lower g s and higher WUEi , while intolerant species had higher SD. This study showed negative or no correlation between SD and g s , A, E, and WUEi and positive correlations between E and A and gs and E.  相似文献   

19.
  • ? We present the longest tree-ring chronology (141 y) of Quercus ilex L. (holm oak), and discuss the species climate-growth relationships and the influence of stand density on tree sensitivity to climate.
  • ? Similarly to Quercus suber L., the most influential climatic variables upon holm oak growth were late spring and early summer precipitation, which enhanced growth, and high temperatures in the previous August and current July, which negatively affected growth.
  • ? High density stands responded to similar climatic factors as low density stands, but their response was generally weaker. Holm oak sensitivity to climate has increased in recent decades, which might be related to increasing temperatures in the region. Sensitivity was higher in low density stands. Additionally, the effect of summer stress on growth seems to have increased during the same period, similarly to other species in the Iberian Peninsula, suggesting that trees are more vulnerable to climatic changes.
  • ? Stand density could buffer the response to climate by smoothing climatic extremes. Nevertheless, the effect of competition might reverse this positive effect at the individual tree level. Precautions should be taken before providing management guidelines regarding the effect of climate change and stand density on holm oak.
    •   相似文献   

    20.
    Lianas are often overlooked in temperate ecological studies even though they are important components of forest communities. While lianas have been shown to damage tropical canopy trees and reduce the growth of juvenile trees, the impact of lianas on canopy tree growth in temperate systems is largely unknown. Growth of trees ≥8 cm dbh was examined over a 9-year period within 50-year old post-agricultural secondary forests in the Piedmont region of New Jersey, USA. Five lianas, Celastrus orbiculatus, Lonicera japonica, Parthenocissus quinquefolia, Toxicodendron radicans, and Vitis species, occurred throughout the forest. Total liana basal area, number of stems, and percent cover within host trees were evaluated to assess liana burdens on 606 previously censused trees. These data were related to tree growth to assess liana impacts. Forest trees were separated based on their dominance in the canopy to determine whether lianas had the potential to influence forest composition. In general, lianas in the forests were fairly abundant, with 68% of the trees having at least one liana present. On average, each tree supported 9.7 cm2 of liana basal area and 23% of the canopy was covered by lianas. Most of the variation in tree growth was related to the dominance of trees within the canopy, with canopy dominant and co-dominant trees growing 2.5× more than suppressed trees. Liana basal area and number of lianas stems were not related to tree growth, but liana canopy cover decreased tree growth. However, not all trees were equally affected as canopy cover of lianas only reduced growth in dominant and co-dominant trees. Lianas were most influential on host tree growth in unsuppressed trees when occupying a majority of the canopy, only a minority of forest trees. This suppression was not related to differential liana colonization of canopy trees as all canopy classes supported equivalent liana burdens. Though lianas impacted only a minority of the trees in this system, some liana species, C. orbiculatus and Vitis spp., are still increasing and may pose future risks to forest growth and development.  相似文献   

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