Plant Biodiversity In Forests Research Articles

Understorey changes after an extreme drought event are modulated by overstorey tree species mixtures in thermophilous deciduous forests

Understorey vegetation is a key component of plant biodiversity in forests. Events of extreme drought are a potential major driver of change of this layer. Although these are predicted to increase in frequency and duration due to climate change, their impacts on understorey communities are still unknown. In this paper, we re-surveyed a set of 36 plots in mature thermophilous deciduous forests eight months after the end of an extremely dry period in 2016–2017. The plots are part of a European network representing a gradient of overstorey richness from 1- to 5-tree species mixtures, with variable composition. We took advantage of this model system to test the hypothesis that species richness and identity of dominant trees in the overstorey may modulate the impact of drought on understorey cover, diversity and composition. In spring 2018, a ca. 50% reduction of understorey cover occurred in both mono-specific and mixed plots. Species evenness and Shannon α-diversity increased in the monospecific plots, due to a reduction of abundance of tree species at juvenile stage and the appearance of non-forest specialists that did not occur in the mixtures. Overstorey species identity effects on understorey diversity were negligible. Overall compositional changes were moderate, though larger in the mixed plots and in those with the less drought-adapted tree species in the overstorey. Ellenberg ecological profile of the community did not change significantly but light values tended to increase in the monospecific plots, contrary to the mixtures. Overall, our findings provide circumstantial support to a higher diversity stability in the understorey of mixed plots shortly after drought, despite compositional variations. More studies and monitoring programs are needed to assess understorey recovery capacity and resilience after such events in the long-term.

Multi-temporal trajectories of landscape change explain forest biodiversity in urbanizing ecosystems

Forest loss and fragmentation negatively affect biodiversity. However, disturbances in forest canopy resulting from repeated deforestation and reforestation are also likely important drivers of biodiversity, but are overlooked when forest cover change is assessed using a single time interval. We investigated two questions at the nexus of plant diversity and forest cover change dynamics: (1) Do multitemporal forest cover change trajectories explain patterns of plant diversity better than a simple measure of overall forest change? (2) Are specific types of forest cover change trajectories associated with significantly higher or lower levels of diversity? We sampled plant biodiversity in forests spanning the Charlotte, NC, region. We derived forest cover change trajectories occurring within nested spatial extents per sample site using a time series of aerial photos from 1938 to 2009, then classified trajectories by spatio-temporal patterns of change. While accounting for landscape and environmental covariates, we assessed the effects of the trajectory classes as compared to net forest cover change on native plant diversity. Our results indicated that forest stand diversity is best explained by forest change trajectories, while the herb layer is better explained by net forest cover change. Three distinct forest change trajectory classes were found to influence the forest stand and herb layer. The influence of forest dynamics on biodiversity can be overlooked in analyses that use only net forest cover change. Our results illustrate the utility of assessing how specific trajectories of past land cover change influence biodiversity patterns in the present.

Tropical forest restoration enriches vascular epiphyte recovery

AbstractQuestionsVascular epiphytes constitute a large proportion of tropical forest plant biodiversity, but are among the slowest plants to recolonize secondary forests. We asked whether tree planting for ecological restoration accelerates epiphyte community recovery. Does the spatial configuration of tree planting matter? What landscape contexts are most suitable for epiphyte restoration?LocationRestored pastures in premontane Coto Brus County, Puntarenas, Costa Rica.MethodsWe surveyed vascular epiphyte species growing on the lower trunks of 1083 trees in 13 experimental restoration sites. Each site contained three 0.25‐ha treatment plots: natural regeneration, trees planted in patches or ‘islands’ and tree plantations. Sites spanned elevational (1100–1430 m) and deforestation (4–94% forest cover within a 100‐m radius around each site) gradients.ResultsVascular epiphytes were twice as diverse in planted restoration plots (islands and plantations) as in natural regeneration; we observed this at the scale of individual host trees and within 0.25‐ha treatment plots. Contributing factors included that trees in planted restoration plots were larger, older, more abundant and composed of different species than trees in naturally regenerating plots. Epiphyte species richness increased with surrounding forest cover within 100–150 m of restoration plots. Epiphyte communities were also twice as diverse at higher (1330–1430 m) vs lower (1100–1290 m) elevation sites. Epiphyte groups responded differently to restoration treatments and landscape factors; ferns were responsible for higher species richness in planted restoration plots, whereas angiosperms drove elevation and forest cover effects.ConclusionsTree planting for ecological restoration enriched epiphyte communities compared to natural regeneration, likely because planted forests contained more, bigger and older trees. Tree island plantings were equally effective compared to larger and more expensive plantations. Restoration sites nearer to existing forests had richer epiphyte recolonization, likely because nearby forests provisioned restoration sites with angiosperm seeds. Collectively, results suggest that restoration practitioners can enrich epiphyte community development by planting trees in areas with higher surrounding forest cover, particularly at higher elevations.

川西亚高山针叶林土壤微生物及酶对林下植物去除的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 川西亚高山针叶林土壤微生物及酶对林下植物去除的响应 DOI: 10.5846/stxb201212131798 作者: 作者单位: 四川农业大学生态林业研究所,四川农业大学生态林业研究所,四川农业大学生态林业研究所,四川农业大学旅游学院,四川农业大学生态林业研究所,四川农业大学生态林业研究所,四川农业大学生态林业研究所,四川农业大学生态林业研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31170423，31270498，31200345）；国家“十二五”科技支撑计划项目（2011BAC09B05）；四川省青年基金项目（2012JQ0008，2012JQ0059）；中国博士后科学基金特别资助（2012T50782） Response of soil microorganism and soil enzyme activity to understory plant removal in the subalpine coniferous plantation of western Sichuan Author: Affiliation: Institute of Ecological Forestry,Sichuan Agricultural University,Institute of Ecological Forestry,Sichuan Agricultural University,Institute of Ecological Forestry,Sichuan Agricultural University,College of Tourism College,Sichuan Agricultural University,Dujiangyan,,Institute of Ecological Forestry,Sichuan Agricultural University,Institute of Ecological Forestry,Sichuan Agricultural University,Institute of Ecological Forestry,Sichuan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:生物多样性与生态系统功能的关系是生态学领域研究的热点与难点。但因受研究手段的限制，有关森林物种组成及其多样性变化对土壤微生物数量和酶活性影响的研究少有报道。采用人工去除灌草层的实验方法，研究了川西亚高山针叶林灌草层丧失对土壤微生物数量和酶活性的影响。结果表明：1）灌草层去除后，土壤细菌和真菌数量以CK（对照） > RH（除草） > RS（除灌），而土壤放线菌数量则以RH > CK > RS；2）灌草层去除后，土壤微生物群落构成发生改变，真菌比例有所下降；3）灌草层去除后，土壤酶活性随之发生变化，各种酶活性均以CK > RH > RS。表明林下灌草层去除，尤其是灌木层去除，导致土壤微生物数量下降、群落构成发生变化以及土壤酶活性下降，从而在一定程度上影响到森林生态系统的物质循环功能。 Abstract:Many challenges have been concentrated on the relationship between forest biodiversity and ecosystem functioning in ecology, since relative slower growth rate of tree and shrub species than herb species makes the tree biodiversity-ecosystem functioning interaction experiments become very difficult. In the past two decades, numerous experiments paid more attentions on the grassland and farmland ecosystem, and investigated the relationships between herbaceous plant species composition and ecosystem process. Theoretically, loss of the tree or shrub species might lead to the drastic changes in soil microbial community and enzyme activities in the fragile ecosystem, due to the sensitivity of soil microorganism to environmental change, which implies that we can understand the relationships between forest plant biodiversity and ecosystem process employing the method of simulated understory plant removal experiment. As yet, far less information has been available on the effects of forest plant loss on soil microbial community and enzyme activities. The subalpine forest located in the eastern Qinghai-Tibet Plateau and the upper reaches of Yangtze River is a typical high-frigid forest ecosystem and fragile ecosystem. Therefore, a three-year shrub and herbaceous plant removal experiment was conducted in the subalpine forest of western Sichuan, in order to understand the linkages of forest plant diversity with microorganism and enzyme activity in the forest soil, from July 2007 to July 2009. The understory removal experiments included the control (CK), herb layer removal (RH) and shrub layer removal (RS). Both shrub and herb plant removals changed soil microbial counts significantly. The ranked order of soil bacteria and fungi counts was CK > RH > RS, and the ranked order of actinomycete count was RH > CK > RS. Understory plant removal changed the composition of soil microbial community, and decreased the ratio of fungi in microbial community. The response of soil microbial community to shrub layer removal was more sensitive than that of herb layer removal. Meanwhile, the removal of shrub and herb layer decreased significantly the activities of invertase, urease, cellulose and dehydrogenase in soils, and the ranked order of incidence was CK > RH > RS. The effect of shrub layer removal on soil enzyme activity was more significant than that of herb layer removal. The results indicated that the removals of both shrub and herb layers altered the composition of soil microbial community and decreased the activities of the measured enzymes in soils of the studied plots, implying that the loss of plant species could change the soil microbial process in the high-frigid forest ecosystem. However, the present study only provides valuable information of short-term herb and shrub layer removal experiment, and long-term experiment needs to carry out in the future. 参考文献 相似文献 引证文献

Changement climatique attendu et biodiversité en forêt

Les auteurs se fondent sur le constat d’un réchauffement récent du climat (Académie des Sciences) et sur la perspective d’une poursuite de ce réchauffement au cours du XXIe siècle (GIEC). Ils explicitent les conséquences à attendre sur la biodiversité végétale présente en forêt de ce réchauffement attendu, selon que les changements du climat seront brutaux ou progressifs. Ils soulignent que les communautés organisées conformément au modèle « de niche » réagiront différemment de celles correspondant au modèle « de sélection ». Ils examinent ensuite les conséquences probables du changement climatique attendu pour la gestion forestière ; à court terme, le maintien d’une diversité génétique élevée dans les peuplements forestiers (aux deux niveaux intraspécifique et interspécifique) semble recueillir un consensus ; pour faire face au long terme, le recours à la « migration assistée » des provenances d’arbres forestiers, vers les plus hautes altitudes ou latitudes, pourrait être inévitable, en prenant soin de bien la raisonner. L’article aborde enfin les conséquences à attendre en matière de politique et de dispositifs de conservation de la biodiversité en forêt. La conservation statique actuellement en vigueur pourrait perdre de sa pertinence, et par voie de conséquence la révision en profondeur de plusieurs réseaux pourrait s’avérer nécessaire (zones « Natura 2000 », sites classés, réserves naturelles, biotopes). À l’avenir, l’adoption d’une stratégie de conservation intégrant la dynamique de la végétation, et faisant une plus large place au génie écologique, semble indispensable. L’article se conclut par quelques considérations et recommandations en matière de politique publique de recherche et de conservation de la biodiversité.

Monitoring forest plant biodiversity changes and developing conservation strategies: a study from Camili Biosphere Reserve Area in NE Turkey

This study was carried out in forestland of Camili Biosphere Reserve (CBR) area in NE Turkey. It was designed to evaluate the consequences of disturbances on changes in secondary forest succession from 1985 to 2005 for monitoring forest plant biodiversity changes and developing conservation strategies. The successional stages were mapped using Geographic Information System (GIS), Global Positioning System (GPS), aerial photos and high resolution satellite images (IKONOS). The results showed that stable stage decreased about 77.96% over the last 20-year time period. Although 701.6 ha conifer forests existed in competition and reaction stages in 1985, none existed in 2005. In overall, about 33.23% of the area decreased, 42.36% did not change and 24.41% increased in different seral stages. Consequently, 8.83% of the area decreased as a whole to indicate that the forest has been developing from stable to nudation stage, that is to say, retrogressive succession is going on in the area. Forest structure and its relationship with plant biodiversity along with its changes over time were determined using FRAGSTATS. We also investigated spatio-temporal configuration of six secondary forest successional stages and generated structural diversity measures. These measures revealed that the landscape has been fragmented, posing a danger to lose the important components of plant biodiversity. Sustainable management of such degraded forests is of crucial importance for plant biodiversity conservation. In conclusion, the study contributes to the development of a framework for effective conservation of plant biodiversity through plant biodiversity integrated Multiple Use Forest Management (MUFM) plans by using the successional stages and plant biodiversity changes.

Relating Plant Biodiversity in Forests with the Spatial Scale of Ecosystem Processes

Plant species diversity of North-Central European forests is quantified by diversity profiles that give different weights to rare and dominant species. Diversity profiles saturate with increasing sample area obeying a hyperbolic saturation model. The paper addresses the question about (1) the spatial scale where this saturation is approached and (2) the nature of related processes. The study is based on about 1,700 vegetation relevés in close-to-nature beech forests and in secondary Scots pine forests which were classified in seven ecosystem types that are distinguished with respect to site factors, dominant tree species, and ecosystem processes. The relevés corresponding to a certain type are successively accumulated to composed relevés with increasing sample area in order to study saturation behaviour. The more weight is given to rare species the larger is the sample area where saturation is approached. The complexity of the processes that determine saturation increases with increasing weight of rare species. With increasing resource availability the part of the occurring plants that have immediate control on local ecosystem processes like primary production, nutrient cycling, and water balance increases. The presented approach allows an estimation of minimum area required for covering vegetation patterns that are related to these processes.

Anthropogenic disturbances and plant biodiversity in forests of Uttaranchal, central Himalaya

Eight forest types varying in disturbance frequencies were identified along an elevational gradient in Uttaranchal, central Himalaya. Low elevation forests were close to human habitation and had high disturbance frequency, while high elevation forests were situated far from the human habitation and had low disturbance. The dominant tree species at low elevation were Pinus roxburghii and Quercus leucotrichophora, while Q. floribunda and Q. semecarpifolia dominated the high elevation forests. Pyracantha crenulata was the shrub present in all the forests except in Q. semecarpifolia forest and Anaphalis contorta, a herb species, was present in all the forests. Disturbance decreased the dominance of single species and increased the plant biodiversity by mixing species of different successional status. Species richness and diversity for all the vegetation layers were higher in low elevation–high disturbance forests. Mean tree density decreased from high to moderate and increased in low disturbance. The shrub density decreased from high to low disturbance while the reverse occured for herbs. High proportion of early successional species in disturbed forests indicated that disturbance induces succession. The mean number of young individuals increasing from high to low disturbance indicates that disturbance adversely affects regeneration. But, however, the high number of young individuals of Coriaria nepalensis, a small non-leguminous nitrogen fixing tree, in disturbed forests shows that the forest is regenerating. This species could be helpful in the re-establishment of original vegetation through triggering the regeneration of these forests. High elevation–low disturbed forests separated from low elevation–high disturbed forests. Forest type and elevation may have more influence on tree richness while shrub and herb richness may be more sensitive to disturbance and forest types.