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1.
Fertilization at planting may improve reforestation productivity on sites frequented by ungulates by stimulating rapid growth above the browse line, allowing seedlings to escape animal damage. Additionally, stored nutrients may aid seedlings in recovery from browse damage. High plant nutrient content may, however, deem seedlings more susceptible to ungulate browsing because of increased foliar protein content and, thus, nutritional value. Research examining the relationship between fertilization of forest trees and ungulate herbivory has been conducted almost exclusively in boreal and temperate zones of North America and Europe, and has produced two common themes. The first is that nearly all trials used broadcast application of fertilizer. This method supplies nutrients to both the target species and competing vegetation, resulting in significant increases in nutritional value for all potential forage. The second common theme is that there is a higher likelihood of browse for fertilized plants. Exceptions to this thread exist, however, because browse preference of fertilized seedlings is apparently species-specific due to differences among species in resource allocation. Palatability appears to interact with the production of plant chemical defenses (i.e., alkaloids, phenylpropanoids, terpenoids). Variations in plant mineral nutrition and secondary metabolite production can play a significant role determining forage preference; however, ungulates under starvation or stress will browse plants of high toxicity or low nutritional value to maintain fitness. 相似文献
2.
外来植物对我国城市生态系统的影响 总被引：1，自引：0，他引：1
外来植物在我国城市园林绿化中起到了重要作用,但在生态与环境保护方面也带来了一些严重问题。本文在简要分析城市植被系统单一性与脆弱性特征的基础上,探讨了外来植物对城市生态系统中土壤理化性状与含水量的影响;分析了在外来植物作用下,城市植物群落结构变化与逆向演替的原因,城市生态系统中物种多样性与生态系统多样性下降原因和遗传多样性改变机理。最后从外来植物生物学特性与适应性以及环境和人为因素这几个方面分析了外来植物种群形成乃至成灾的机制。 相似文献
3.
Herbivory may be an important factor affecting seedling survival of exotic species invading new habitats. We evaluated the effect of vertebrate herbivory on the seedling survival of two widely planted and invasive tree species (Pinus radiata and Eucalyptus globulus), in a Mediterranean-type ecosystem of central Chile. An important role of herbivory on seedling survival of these two species in their introduced ranges has previously been documented. However, this has mainly been evaluated in forest plantations where habitat and vegetation conditions differ from wild habitats in which invasion occurs. We planted seedlings with and without protection against vertebrate herbivores in different aspects (a mesic south-facing slope and a xeric north-facing slope) and vegetation cover (open sites and sites with patchy tree cover). We found that regardless of aspect or vegetation cover, herbivory, in this case mainly caused by exotic vertebrates, significantly and negatively affected seedling survival of both species. However, while the effect of herbivory on P. radiata was significant in every vegetation and habitat condition, for E. globulus, the effect of herbivory was significant only for open sites in the mesic habitat. These results suggest that, as observed in forestry plantations, vertebrate herbivory may constrain seedling establishment of these two exotic trees and potentially impede the invasion. However, the importance of herbivory in controlling exotic species may vary depending on the vegetation and habitat conditions in some species such as E. globulus. 相似文献
4.
尾叶桉为高大乔木,其生长快、干形通直、材性好,原始分布于印度尼西亚.我国自1976年开始引种尾叶桉,分别在广东、广西、海南等地建立了种源/家系试验林,保存了大量的遗传资源并营造了大面积的人工林,现已成为我国推广栽培面积最大的桉树树种之一.桉属树种全部为外来引进树种,我国没有自然分布,不能与我国本土树种发生杂交,不存在与我国本地树种发生基因交流或杂种化的风险.桉树在我国能正常开花结实,但种子特别小,很难自然发芽成活,不能自然更新和扩张,不会出现自发入侵本地生态系统、占据其它树种栖息地、造成生物入侵危害的现象.桉树与其它植物的水肥竞争或化感作用导致其林下植被贫乏还存在争论,但我国华南地区年降雨量多,林下植被一般都很丰富,也有多种动物栖息.大量引种栽培试验也证明,桉树在我国华南一带种植对其它植物的化感作用不明显,桉树人工林的发展完全可以人为控制. 相似文献
5.
Cynthia D. Huebner Randall S. Morin Ann Zurbriggen Robert L. White April Moore Daniel Twardus 《Forest Ecology and Management》2009
Intensive Forest Inventory and Analysis (FIA) plot data collected in the Allegheny National Forest (ANF), Pennsylvania, between 1999 and 2006 were evaluated for their ability to predict ANF’s vulnerability to invasion by exotic plants. A total of 26 variables classified by biotic, abiotic, or disturbance characteristics were examined. Likelihood of colonization by invasive exotic and non-invasive exotic plants was analyzed using a logistic regression model. Approximately, 11% of the 449 species documented in these plots were exotic, which is higher than has been found in other northeastern forested plots. Only 1% of the ANF flora was invasive exotic plants and these were at low abundance, confirming that most invasions are still at an early stage of establishment. Sites richer in native or non-invasive exotic plants and with more alkaline soils were more likely to be invaded. Younger forests, forests with non-forest patches present, and forests rich in native species were more likely to be colonized by exotic (invasive or non-invasive) plants. Frangula alnus, which is starting to spread locally, differed from the other invasive exotic species in terms of its association with high sapling density to tree density ratios, high soil nitrogen levels, and the presence of fire. Variables representing mortality due to beech bark disease and distance to the nearest exotic planting manifested counterintuitive results. In both cases, the combined occurrence of mortality due to beech bark disease or a close (less than 500 m away) known propagule source and the presence of an invasive or non-invasive exotic plant was rare. We encourage increased use of intensive sampling for FIA in the U.S.A. and similar monitoring programs in other countries, but suggest adding a step to the plot selection phase that would allow forest-wide or regional stratified sampling of typically coarse-scale variables, such as historic or predicted defoliation or fire events, and forest or land type. A more accurate picture of the importance of disturbance variables in defining forest vulnerability to plant invasion may be achieved. 相似文献
6.
D. P. J. Kuijper 《European Journal of Forest Research》2011,130(6):895-909
Across Europe, ungulate numbers have greatly increased over the past decades, leading to increasing concerns about the ecological
and economical impacts and pleas for stronger population control. However, focussing on population control only ignores other
underlying factors which may enhance the wildlife–forestry conflict. I reviewed factors which shape herbivore top-down effects
in natural temperate forest systems aiming at understanding how these interactions are altered in managed forests. Carnivores
are important in modifying ungulate–plant interactions. They can directly influence the numbers of ungulates, but this effect
is dependent on productivity and predicted to be smallest in highly productive temperate forest. Indirectly, they modify herbivore
top-down effects by creating a landscape of fear. Despite the abundance of knowledge from American systems, there is a lack
of knowledge on how this process might work in European systems. Next to carnivores, abiotic conditions interact with herbivory
by influencing forage quality and availability. Forest gaps lead to concentration of ungulates and their effects, due to increased
forage supply. Abiotic conditions also influence the response of plants following herbivory, which can be tolerated by showing
increased regrowth or resistance due to chemical or physical defence. In typical managed forest systems, carnivores and abiotic
conditions which shape ungulate top-down effects in natural forests are altered or absent. Human hunting might replace the
direct effects of carnivores, but does not replace their indirect effects. Forestry practices also have modified herbivore–plant
interactions in several ways, creating a forest with lower ungulate carrying capacity and higher sensitivity for ungulate
browsing. These changes logically increase the strength of herbivore top-down effects in managed forests and increase the
wildlife–forestry conflict. To reduce this conflict, aiming only at reducing wildlife numbers is predicted to have little
effects when they do not coincide with habitat ameliorations. Forestry practices may therefore greatly enhance the conflict
that exists between wildlife and forestry but can also be an important tool to reduce this conflict by adapting management
practices that allow more natural functioning of forests systems. 相似文献
7.
广西十万大山自然保护区外来入侵植物研究 总被引：2，自引：0，他引：2
十万大山属北热带山地,有着丰富的生物多样性,但目前已遭到外来种植物入侵。通过实地调查和查证文献资料,初步确定十万大山自然保护区内外来入侵植物有23种,隶属于12科21属,其中菊科种类最多,6种,占入侵植物总数的26.1%;其次为苋科,3种,占入侵植物的13.0%。从来源看,23种入侵植物中,有21种来自热带美洲,占入侵植物种的91.3%。23种入侵植物均为r-选择对策种,其中有草本20种,占入侵植物种类总数的87.0%。23种入侵植物几乎全部是由人类活动直接或间接引入。最后对保护区内入侵植物的危害性及防治措施也作了初步的分析。 相似文献
8.
Herbivores, such as beavers (Castor canadensis) and ungulates, can dramatically alter the species composition and structure of riparian vegetation communities. We examined how four different levels of beaver presence and ungulate density influenced the structure and composition of riparian vegetation communities in the mixed-wood boreal region of east-central Alberta, Canada. Beavers, as central-place foragers, focus on similar species utilized by the six ungulate species in our study area. However, we found that vegetation responded differently relative to the percent cover and heights of emergent, shrub, herbaceous dicots, and tree species depending on the varying combinations of beaver presence and ungulate densities. There was an obvious negative effect of ungulate herbivory on shrub heights and cover; however, we were unable to find any significant effects on the overall composition and structure of vegetation communities that were exclusively related to beaver activities. In areas with no beavers and lower ungulate densities there was a positive growth response in preferred species (e.g., Salix spp., Prunus spp.), which clearly demonstrated the degree of combined influence that these herbivores have on riparian communities. In these areas, Salix spp. was four times shorter than in areas where beavers were not present and ungulate densities were lower. In addition percent cover was lowest for emergent vegetation and herbaceous dicots in areas with higher ungulate densities. Many studies focus on single-species effects on forage resources, yet our research shows that the study of combined effects of multiple herbivores can provide a new insight into these complex systems. 相似文献
9.
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. 相似文献
10.
Live fences as tools for biodiversity conservation: a study case with birds and plants 总被引：2，自引：1，他引：1
Live fences may act as tools for biodiversity conservation by providing habitat for native species and increasing connectivity
in the landscape. We studied the influence of live fence characteristics on species richness and fence use by birds by examining
both local and landscape factors. We studied three types of live fences: planted fences of a native tree, planted fences of
an exotic, and spontaneous. They were either connected to forest fragments or isolated, and were all within a pasture matrix.
Spontaneous and planted live fences maintain a diverse plant (77 shrub and tree species) and bird communities (98 species).
Fence types strongly differed in vegetation composition and structure. We found that by analyzing each fence characteristic
independently, there was no difference in bird richness or abundance. However, there was a significant correlation when plant
richness, structure, and connectivity were analyzed together. This could be the result of some variables counterbalancing
each other. Birds used fences for a variety of purposes including foraging, breeding, and moving across the landscape. Native
birds and plants used live fences as habitat and refuge in a landscape where large forest tracts have been lost for decades.
Live fences in conjunction with small forest fragments maintain a diverse array of plant and birds species that are a subsample
of the species originally found in the landscape before extensive deforestation. We recommend the establishment of live fences,
allowing growth of spontaneous understory. 相似文献
11.
12.
Suzanne M. Owen Carolyn Hull Sieg Catherine A. Gehring Matthew A. Bowker 《Forest Ecology and Management》2009
Mechanical mastication is increasingly prescribed for wildfire mitigation, yet little is known about the ecological impacts of this fuels treatment. Mastication shreds trees into woodchips as an alternative to tree thinning and burning the resulting slash, which can create soil disturbances that favor exotic plants. Previous research on mastication has not simultaneously considered both the responses of soil organisms and understory plant communities. We compared mastication to slash pile burning (both 6-months and 2.5-years post-treatment) and untreated controls in pinyon–juniper (Pinus edulis–Juniperus osteosperma) woodland and measured soil properties, arbuscular mycorrhizal fungi (AMF) and understory plant composition. Our results showed that slash pile burns had severely degraded soil properties and low AMF abundance and richness compared to untreated or mastication plots. Pile burns were dominated by exotic plant species and had approximately 6× less understory plant abundance and richness than untreated plots. Only two variables differed between mastication and untreated plots 6-months post-treatment: mastication had lower soil temperature and higher soil moisture. Mastication plots 2.5-years post-treatment had more plant cover and richness than untreated plots or pile burns, although non-native Bromus tectorum cover was also greater and AMF spore richness was lower than untreated plots. The structural equation model (SEM) we developed showed that plant cover strongly influenced AMF abundance (0.50) and both plant cover (0.36) and AMF (0.31) positively influenced soil stability. In the short-term, mastication is a preferable method as it creates fewer disturbances than pile burning; however long-term impacts of mastication need further study as this practice could affect native plant communities. Our results suggest that the manner in which woody debris is treated following tree thinning has an important influence on soil stability and native plant biodiversity. 相似文献
13.
Wooded pastures grazed by livestock are believed to be landscapes that provide favourable conditions for spontaneous regeneration of oaks, including Quercus robur. A key mechanism for oak regeneration in these systems is ‘associational resistance’, spatial association with unpalatable plants which offer protection against herbivory. There is little knowledge on how oak regenerates without livestock grazing and in the presence of only wild large herbivores. We studied this in an area (114 ha) abandoned from agricultural use and in the early 1980s incorporated into the Bia?owie?a National Park, Poland. Its ungulate community consists of native red deer, European bison, roe deer, moose and wild boar. Secondary succession has led to the development of a mosaic habitat including tree and tall shrub groves (29% of the area), open meadow communities (60%), and edge, transitory zone between groves and meadows (11%). Our systematic inventory assigned oaks to height classes (0-0.2, 0.2-0.5, 0.5-1.3, 1.3-2.5, 2.5-5.0, >5.0 m), dichotomous shape characteristic (regular vs. “bonsai” sapling), as well as a habitat definition, in particular the characteristics of woody vegetation in the immediate surroundings of oaks. A selection of 17 oaks was subject to coring for the comparison of growth dynamics. Oak density was highest inside groves, with 504 oaks ha−1, and in the edge zone (493 oaks ha−1) and lowest in meadows (47 oaks ha−1). Most of the 0-5-m oaks (62%) grew without another woody plant species within 1 m radius. The remaining oaks (38%) were associated mainly with Rubus idaeus and saplings of Carpinus betulus and Populus tremula - all highly ungulate-preferred species. The age (0.5 m above ground) of cored oaks in grove and edge habitats varied from 11 to 37 years, indicating continuous recruitment since agricultural abandonment. The initial growth dynamics of the more mature oaks did not differ from that of present “bonsais,” supporting the idea that browsing is not an unconditional impediment and that “bonsai” can be a temporary stage of successful oak development. In contrast to other studies, we found that associational resistance from unpalatable plants is not necessary to secure successful oak regeneration in woodlands subject to browsing by wild ungulates. This might have been possible because of the abundance of highly attractive vegetation making oak relatively unpreferred by ungulates. We suggest that the observed secondary succession provides a contemporary analogy of historic processes that resulted in the establishment of broadleaf forests with a substantial proportion of oak. 相似文献
14.
Anaïs de Almeida Campos Cordeiro Sara Deambrozi Coelho Nina Celli Ramos João Augusto Alves Meira-Neto 《Agroforestry Systems》2018,92(6):1495-1505
The Serra do Brigadeiro State Park (PESB) is one of the largest fragments of Brazilian Atlantic Rainforest, and it is relevant for native species conservation. However, monocultures settled around the Park resulted in extensive open areas that facilitate the establishment of alien species on the PESB perimeter, which may threaten native species conservation therein, since biological invasion is the second main cause of global biodiversity loss. In this region, there are also farmers planting agroforestry systems (AFS), characterized by tree-based intercropping, which are structurally more similar to the Atlantic Rainforest reminiscent fragments present in the region and may limit local occurrence of potentially invasive exotic weeds for several reasons, such as the high levels of shade provided by trees, the groundcover that result from loss of tree leaves and the increased competition for belowground resources. This study aimed to test whether AFS limit exotic species establishment when compared to monoculture systems. Accordingly, three coffee monocultures and three agroforestry coffee plantations around the PESB were studied. In each of the six study areas, 30 plots of 1 m2 were established between the lines of coffee plantation, where all species present were surveyed. In both treatments, rarefaction curves were constructed to evaluate native and exotic richness, and diversity of these two categories was estimated through Simpson index inverse (1/D). All 13 sampled exotic species were present in monocultures, but only three of them occurred in AFS. Besides, alien diversity in monocultures (\(1/D\) = 2.173 ± 0.011) was significantly higher than in AFS (\(1/D\) = 1.031 ± 0.001). Such changes in alien plant community between land-use show that AFSs limit invasive species establishment. Therefore, when planted around protected areas, AFS may contribute to the control of biological invasions and to biodiversity conservation. 相似文献
15.
Rodolfo Cesar Real de Abreu Geissianny Bessão de Assis Sergianne Frison Andrea Aguirre Giselda Durigan 《Forest Ecology and Management》2011,262(8):1452-1459
There is a widespread view that forest plantations with exotic species are green deserts, unable to sustain biodiversity. Few studies have demonstrated, however, that planted stands of exotic trees have a greater negative effect on the plant diversity of savanna vegetation. We compared the native woody flora under four stands of slash pine of about 45 years old with four stands where the previously existing native Cerrado vegetation was preserved and protected from disturbances for the same period, has changed into dense vegetation - the “cerradão”, at Assis municipality, São Paulo State, Brazil. Aiming at understanding the potential ecological filters driving these communities, we assessed air and soil humidity, light availability and classified the native species on the basis of shade tolerance, dispersal syndrome and biomes in which they occur (Atlantic Forest or Cerrado). We recorded an average of 70 (±13) species under pine stands and 54 (±16) species in cerradão. Of the total of 136 species recorded, 78 occurred in both habitats, eight were exclusive to the “cerradão” (shade tolerant and also occurring in forest ecosystems) and 18 were recorded only under pine stands (82% heliophytic, exclusive to the Cerrado biome). Among the functional attributes and abiotic variables analyzed, only light availability explained the floristic differences found. Since richness was higher under pine, we refuted the hypothesis that exotic species constrain the establishment of the native species richness in the understory. On the other hand, the dark environment under the closed-canopy of the “cerradão” acts as a filter inhibiting the establishment of typical Cerrado species. Since pine stands, if managed in long cycle, maintain a reasonable pool of Cerrado endemic species in the understory pine plantations may be a good starting point for savanna restoration. 相似文献
16.
园林植物引种是历史悠久且永恒的主题,也直接导致了外来植物的比例升高;与此同时,气候变化和土地利用方式的改变又致弱了生态系统韧性,加剧了生物入侵风险。文章在介绍引种和入侵基本概念的基础上,阐述城市生境的可入侵性和外来植物的入侵能力,并提出了预防、控制和利用入侵植物的具体措施,旨在为增加城市生物多样性及有效防止入侵提供对策。 相似文献
17.
崔茂欢 《内蒙古林业调查设计》2010,33(4)
位于云龙县境内的云龙天池自然保护区,其主要保护对象为以滇金丝猴为代表的珍稀濒危野生动植物资源及其栖息环境、天池湿地生态系统和以暖温性、寒温性针叶林为代表的原始森林生态系统。文章阐述了保护区动物、植物和植被类型多样性概况。评价其生物多样性特点,分析了生物多样性保护面临的主要威胁和限制因素,提出了社区共管、加强执法等管理措施。 相似文献
18.
Predation risk is an important factor influencing the distribution of ungulates and their impact on forest structure. However, simultaneous predation risk by wolves and humans is rarely considered in the analyses of habitat selection by ungulates. We counted ungulate pellets on transects to analyse the influence of wolves and humans on ungulate density distribution in the Białowieża Forest, Poland. We assessed whether (1) forest exploitation influenced ungulate habitat selection, (2) ungulate density was higher in areas without human hunting, (3) ungulates avoided the surroundings of a major road, (4) prey density was higher in the strife zone between home ranges of wolf packs both in the presence and absence of human hunting, (5) ungulates avoided areas selected by wolves, and (6) wolf kill sites were in high prey density areas. Red deer (Cervus elaphus) and wild boar (Sus scrofa) selected unexploited over exploited forests and areas without hunting, whereas roe deer (Capreolus capreolus) preferred exploited forests. Wild boar and European bison (Bison bonasus) avoided the area within 300 m of a major road, whereas we could not detect any avoidance by red or roe deer. Prey density was not higher in wolf strife zones, regardless of human hunting. Ungulates did not avoid areas selected by wolves. Wolves killed red deer in areas with prey density of about 4 red deer/km2, regardless of whether the average red deer density in those areas was higher or lower. We conclude that habitat alteration by forest exploitation and hunting by humans influenced the density distribution of ungulates more than predation risk by wolves. 相似文献
19.
Most of the remaining grassy woodland in south-eastern Australia exists as remnants on private land in agricultural landscapes. These have been subjected to various forms of disturbance including exotic plant invasion and livestock grazing. Little is known about the invertebrate communities in these remnants, which could contribute greatly to the diversity and function of these ecosystems. We need to know what invertebrates are present and how they respond to different types of land management, such as livestock grazing, in order to conserve them. 相似文献
20.
Jim Latham 《Forest Ecology and Management》1999,120(1-3):13-21
Mammalian herbivores vary in the degree to which they browse, graze and cause physical disturbance, and so vary in the effects they have on the structure and composition of forest ecosystems. To create predictive models of the interactions of forest ecosystems with herbivore communities, an appreciation of the interactions between the species of herbivore themselves is necessary. This paper reviews interspecific interactions of ungulates, methods used in studying them, and seeks to identify areas to which future research should be directed in the context of European forest systems. Methods that have been used to provide information on interactions include: comparative resource studies, niche theory, physiological and anatomical analyses, modeling and foraging theory, and population studies. The most commonly reported types of interactions appear to be competition and facilitation. Behavioural and social interactions between species are potentially important, but evidence for these is scarce and often anecdotal. It is suggested that there may be considerable potential for ungulates to interact in European forests which are often significantly altered from their natural state. Future research should aim at refining the theoretical understanding of interspecific interactions, particularly between ungulates with different feeding ecologies. The roe deer (Capreolus capreolus) has a major impact on forest ecosystems and is increasing its range throughout Europe. However, there is evidence that it may be displaced or out-competed by a number of ungulate species, and it is suggested as being research priority to quantify these effects. 相似文献