Sub-canopy Layers Research Articles

Moths respond to key habitat structures in conifer plantations managed as irregular high forest

Conifer plantations need to deliver greater multi-functionality beyond the production of timber. This includes the support of biodiversity and associated ecosystem functioning. Forest managers are increasingly adopting novel, more sustainable forest management techniques such as irregular silviculture, a type of continuous cover forestry, to manage plantations, in response to climate change. This may confer benefits to important elements of woodland biodiversity such as moths, by creating plantations that have diverse vertical structure and a permanent canopy (called irregular high forest). In this study at two estates in south-west Britain we specifically tested whether moth species richness and abundance (at the guild and overall level) were associated with (1) surrounding land cover types and (2) habitat structures within stands undergoing transformation using irregular silviculture. A total of 268 species of 11,582 individuals were recorded. Moths responded to all four landscape cover types, negatively to arable and conifer woodland, positively for broadleaf woodland, and both positively and negatively for improved grassland. Moth richness and abundance had a positive association with basal area (albeit below standard even aged stocking rates with most plots around 40–45 m2ha) and a weak positive association with higher vertical structural complexity (indicated by a more developed understorey and sub-canopy layers). Moth abundance had a moderate positive association with broadleaf canopy where we recommend plantations should have at least 10–15 % broadleaf canopy cover. Moth richness and abundance were negatively associated to mean tree diameter and canopy openness. Many of these features are more prevalent in stands further progressed towards irregular high forest. We show how moth communities can be maintained via more sustainable forestry management techniques that increase overall habitat and structural complexity.

Dynamic, multi-scale analyses indicate site- and landscape-level forest cover drive Yellow-billed and Black-billed Cuckoo interannual turnover.

Studies of habitat use in breeding birds often assume species have relatively stable breeding distributions. Some species, however, display considerable year-to-year variability, complicating efforts to determine suitable or preferred habitats. After returning to their breeding range, Black-billed Cuckoos (Coccyzus erythropthalmus) and Yellow-billed Cuckoos (C. americanus) are thought to range widely before nesting, resulting in high rates of interannual breeding-site turnover, potentially contributing to conflicting habitat associations found in past studies. However, difficulty detecting these rare and declining species could lead to overinflated estimates of interannual turnover. Using broadcast surveys to increase detection probability, we collected detection/non-detection data in 2019 and 2020 at 41 publicly owned sites in Illinois and performed a dynamic, multi-scale occupancy analysis for each species to separate detection probability from potential interannual turnover and determine landscape and small-scale variables driving habitat use and occupancy dynamics. We found strong support for interannual turnover for both species based on poor performance of non-dynamic models and variation in estimated annual occupancy (20% and 21% increase between years for Black-billed and Yellow-billed Cuckoos, respectively). Black-billed Cuckoos persisted at sites with less forest in the surrounding landscape and used areas with denser understory vegetation. Yellow-billed Cuckoos colonized sites with greater canopy cover, avoided developed landscapes, and used areas with a shorter subcanopy layer. The dynamic nature of habitat use in these two cuckoo species suggests the importance of coordinating management and conservation across a broader spatial scale. Managing for larger patches of dense shrubs in less forested landscapes would benefit Black-billed Cuckoos while Yellow-billed cuckoos would benefit from management creating forested areas with open understories in less-developed landscapes.

국립공원 육상생태계 생태·환경적 차이에 따른 탄소저장량 특성 연구

This study aimed to assess carbon storage by establishing 222 fixed survey plots in 22 national parks and analyzing the plant ecological characteristics of the survey areas to determine any relationships. To achieve this, we analyzed plant community structure and species diversity indices based on survey information for each plot. Initially, the plant communities for the entire survey plots were classified into four types. Group I was characterized as the Taxus cuspidata-Abies koreana community, Group II as the Acer pictum community, Group III as the Quercus-Pinus densiflora community, and Group IV as the Pinus strobus community. Among these four types, Groups I, II, and III were distinguished by elevation, and we observed a linear arrangement along the second axis as the carbon storage in the deciduous layer increased, indicating that Groups I, II, and III could be differentiated based on carbon storage in the deciduous layer. Soil carbon storage showed a similar trend, while woody carbon storage did not exhibit a clear group-based trend. Furthermore, when examining the relationship between carbon storage and species diversity, we found a weak positive correlation between soil carbon storage and species diversity, but no significant correlation with vegetation carbon storage. However, it's important to note that these results only reflect the findings based on the survey results for trees with a diameter at breast height of 6 cm or larger and sub-canopy layer trees. Additional data collection for shrub and ground cover plant species is necessary to further develop these findings.

Flowering and fruiting of the dioecious canopy tree Cercidiphyllum japonicum over an 8-year period in central Japan

ABSTRACT To investigate the reproductive traits of the dioecious canopy tree Cercidiphyllum japonicum, we performed visual surveys from 2000 to 2007 to assess the flowering and fruiting of 59 individuals in a riparian forest in central Japan. Flowering and fruiting were assigned to ranked categories, where 1 indicated none and 5 indicated abundant production throughout the canopy. In addition, we used conical seed traps to assess the seed production of this species at the center of the forest. Of the 59 study individuals, 20 female and 26 male trees were >26 cm in diameter at breast height (DBH) and classified into the canopy layer. The remaining smaller individuals were non-reproductive and, excluding one, were classified into the sub-canopy layer. We estimated that C. japonicum may require 100 years of growth to reach 26 cm in DBH in a riparian forest. Both sexes produced abundant flowers in all years, and males exhibited slightly higher flowering and lower variation than females. Individuals with a DBH > 50 cm tended to flower very abundantly, and this pattern was consistent with trees over 1 m in DBH. Seed-trap surveys indicated that C. japonicum seeds were dispersed annually, with inter-annual variation. We conclude that C. japonicum is quite slow to reach sexual maturity, but can produce very abundant flowers, fruits, and seeds annually throughout its long lifespan.

Characterizing subcanopy structure of Mediterranean forests by terrestrial laser scanning data

Vegetation structure is one of the key factors in forest ecosystems. Especially understory structure has major implications for wildlife habitat selection, reproduction, and survival. Structural indices traditionally used to characterize understory vegetation are based on field vegetation surveys describing general features such as leaf area index (LAI), canopy cover or vegetation height, hiding much of the three-dimensional vegetation structure complexity. The application of terrestrial laser scanning (TLS) in forest ecological and management applications is becoming more effective. In this study, we use TLS data to quantify spatial attributes of forest subcanopy in four different forest strata ranging from 0.5 m to 10 m from the ground. We collected data in 12 plots of mature European beech (Fagus sylvatica L.) forests and 12 plots of mature black pine (Pinus nigra subsp. laricio Maire) forests, located in the Sila National Park, Italy. We propose a TLS-based approach to estimate a fine-scale vegetation density using the Plant Density Index (PDI) and to test the PDI at different height classes. We found a significant relationship between the PDI and the number of trees belonging to the dominant layer, using the Spearman correlation coefficient (r = 0.83, pval = 0.001). Basing on PDI values, a cluster analysis of the four subcanopy strata was carried out for deriving clusters of structurally homogeneous forest plots. Results identified three clusters in terms of the vegetation features in the horizontal height classes: the first cluster primarily includes Beech forests characterized by plots with the highest tree densities; the second one includes both Beech and Pine forests characterized by dense ground vegetation and shrubs and an intermediate tree density; the third group is represented by Pine forests with massive presence of vegetation lower strata and moderate tree density. Then, PCA allowed identifying the relationship between the considered subcanopy layers and forest plots.

Nemoralisation of Pinus sylvestris and Picea abies Forest Stands in the Hemi-Boreal Zone: A Case Study from Latvia

Abstract At the beginning of the 21st century, in extensively managed mature and over-mature conifer stands (Pinus sylvestris and Picea abies) in Latvia, establishment of native deciduous broad-leaved (Acer platanoides, Tilia cordata, Quercus robur and Ulmus laevis), as well as alien broad-leaved species (Acer pseudoplatanus and Tilia platyphyllos) has been observed. The establishment of deciduous broad-leaved species in coniferous stands is a process known as nemoralisation of coniferous stands, which is characterised by a large number of seedlings of broad-leaved species, young trees and the formation of a subcanopy layer in stands. Based on the age measurements of individuals of broad-leaved species trees, the establishment of some individuals into the studied coniferous stands occurred 40–50 years ago — in the 1970s–1980s. However, the predominant age of alien broad-leaved tree species in the study plots was 15–25 years, i.e. the introduction of large numbers of seedlings of these species in the coniferous stands occurred at the end of the 20th century. In this manner, in the final phase of the conifer replacement process, stable, mostly shade tolerant, mixed stands consisting of 3–4 species have formed, in which spruce is often found together with broad-leaved species.

The phytogeography of moist forests across Eastern Zimbabwe

Background and aims – During the 1970s, a comprehensive survey of moist forest areas across Zimbabwe’s Eastern Highlands was carried out, from Nyanga in the north to Chirinda Forest in the south. All tree stems 8 cm diameter or greater in both canopy and sub-canopy layers were measured in 176 quarter-hectare plots, and plots were then classified into 12 altitude-related forest types. The aim of the present study is to categorise the woody species recorded in these plots in terms of their chorological status. The findings are compared to similar analyses from moist forests across Malawi.Material and methods – All tree species recorded during the initial survey were listed and placed into 12 described chorological (phytogeographical) categories based on their continental distribution. Their occurrence across the 12 previously described forest types is given. Key results and conclusions – A total of 211 tree species was recorded from 176 plots. Most species (86, or 40.8%) are Afromontane endemics or near-endemics, while 48 species (22.7%) are Guineo-Congolian linking, 31 (14.7%) are Eastern endemic or near-endemics, and 16 (7.6%) are sub-Afromontane endemics or near-endemics. The remainder comprise African linking and Zambezian species. This shows that species of the moist forests of eastern Zimbabwe form a complex phytogeographical mix. While Afromontane species dominate at high altitudes, Guineo-Congolian and Eastern species become more common at lower altitudes. In terms of proportions of chorological categories, results were found to be similar to those from forest studies in Malawi.

天目山常绿落叶阔叶林群落垂直结构与群落整体物种多样性的关系

以浙江省天目山1 hm²常绿落叶阔叶混交林样地调查数据为基础，运用K-means聚类方法将DBH≥1 cm的个体根据树高划分为不同林层，研究比较了各个林层的物种多样性特点；利用通径分析方法和决策系数定量计算各个林层物种多样性对群落整体物种多样性的直接作用和间接作用，天目山常绿落叶阔叶林垂直结构对群落物种多样性构成的影响。结果表明：（1）天目山常绿落叶阔叶林群落层次结构丰富，树高由1.4-36.5 m依次可分为灌木层、亚冠层、林冠下层、林冠中层和林冠上层。（2）天目山常绿落叶阔叶林群落从灌木层依次往向上，物种丰富度、多度、特有种数量、Shannon-Weiner指数和Simpson指数均呈下降趋势。（3）灌木层对群落物种多样性的贡献最大且远高于其他四个林层，其中灌木层对群落整体物种多样性Shannon-Wiener指数、Pielou指数以及Simpson指数的决策系数分别为0.850、0.651、0.755。（4）林冠下层、林冠中层和林冠上层密度的大小对灌木层的物种数目有明显的影响，林冠层密度越大，灌木层群落的物种数目越少，复杂程度越低；偶见种和稀有种对群落物种多样性的维持具有特殊作用。综上，研究认为森林群落的垂直结构在维持森林群落整体物种多样性中具有关键作用，而灌木层在群落整体物种多样性构成中具有决定作用，森林群落中稀有种、偶见种多少在群落物种多样性构成中具有特殊作用。;Based on the survey data of 1 hm² deciduous and evergreen broadleaved forest plot in Tianmu Mountain of Zhejiang Province, we assessed species biodiversity by K-means clustering method, the individuals with diameter at breast height(DBH) ≥ 1 cm was divided into different forest layers according to tree height, and the features of species diversity in each layer were computed, compared, and contrasted. In addition, the direct and indirect biodiversity impacts also evaluated by using path analysis, namely, the quantity of decision coefficients. The objective of the study was to reveal the influence of vertical structure on community species diversity in an evergreen deciduous broad-leaved forest community. The results demonstrated that:(1) the forest community had multiple-layered vertical structure, which could be divided into five layers:shrub layer (1.4-4.2 m), sub-canopy layer (4.3-7.6 m), lower canopy layer (7.7-13.4 m), middle canopy layer (13.5-21.5 m), and upper canopy layer (21.6-36.5 m). (2)The species richness,abundance,the number of endemic species, Shannon-Weiner index and Simpson index of the community appeared a downward trend from bottom to top layers. (3)Shrub layer was the largest contributors to the community overall species diversity index and was much higher than the other four forest layers. And the decision coefficient of shrub layer towards overall species diversity of community that Shannon-Wiener index, Pielou index and Simpson index was 0.850, 0.651, and 0.775, respectively. (4) The density of lower canopy, middle canopy, upper canopy had a negative impact on the species number of the shrub layer. The larger density of the forest canopy was, the less the number of species would become in the shrub community as well as the complexity. In addition, the occasional and rare species in the shrub layer also played a key role in maintaining the species diversity of the shrub layer. In conclusion, the vertical structure of the community was critical in maintaining the overall species diversity of the given forest community. The shrub layer played a decisive role in the composition of overall species diversity, besides the number of occasional and rare species also played a key role on the composition, thus, species diversity of the community.

Forest wind regimes and their implications on cross-canopy coupling

An analysis of wind regimes across forests of varying density and height is presented. The hockey stick-like dependence of the friction velocity on the mean advective wind speed is used to determine the threshold between the weak-wind and the strong-wind regime for the entire canopy. Such thresholds are compared across four different sites. The height dependence of thresholds within the canopy is inverted compared to the one above grassland sites. This can be understood by extending the accepted interpretation for weak-wind thresholds from grassland sites to forested sites.Even for large fluctuations above the canopy, the fluctuations of the vertical wind velocity in the subcanopy remain small during weak-wind situations. Correspondingly, in the strong-wind regime, turbulence in the subcanopy remains strong in spite of reduced above-canopy turbulence. This fact suggests that previously used methods for determining the degree of coupling across the canopy layer based upon the ratio of the vertical wind variance between the above-canopy and subcanopy may prove erroneous. Furthermore, it emphasizes the significance of mechanisms generating subcanopy turbulence other than above-canopy turbulent transport and shear.The transport of mass and energy between the subcanopy and above-canopy layers is significantly reduced during the weak-wind regime. In particular, the vertical turbulent transport is reduced by more than one order of magnitude. This suggests a decoupling of the subcanopy layer during weak-wind situations and allows for the accumulation of carbon dioxide originating from soil respiration in the subcanopy layer during the weak-wind regime.

When and why do trees begin to decrease their resource allocation to apical growth? The importance of the reproductive onset.

Trees reduce their allocation to apical growth compared with that to radial growth during later life stages. This has often been attributed to hydraulic and mechanical limitations; however, a growth-reproduction tradeoff might also play an important role. To test whether the height-diameter (H-D) relationship in trees changes with the timing of the onset of reproduction, we analyzed the H-D relationship of 13 deciduous broad-leaved tree species in a Japanese old-growth temperate forest using linear and segmented-linear regression models. These models showed a better fit than common continuous models (simple allometry and saturating curve). For 11 out of 13 species having break points on the H-D lines, we assessed whether the height at the breakpoint (BPH) was related to the height at the onset of reproduction determined by multiyear observatory records on several trees. Although BPH estimates for these 11 species were highly variable, most were within 3.1m of the stable flowering height (staFLH), or the height at which trees achieve the ability to flower regardless of their growth conditions. The interspecies mean value of the difference between staFLH and BPH was only 45cm, which suggested a causal relationship between these parameters. BPHs of nine out of 11 species were within the canopy layer and, for the two remaining species, were within the subcanopy layer. These results suggest that several species in this forest begin to reduce their allocation to apical growth around the canopy layer at the onset of stable reproduction.

Bird Species Richness in Relation to Land-Use Patch Structure and Vegetation Structure in a Forest-Agriculture Mosaic

Habitat degradation and fragmentation are serious threats to global biodiversity. Attributes of vegetation structure and patch structure have been considered critical factors in sustaining species diversity, but their relative importance remains unclear. This study aimed at identifying key vegetation and patch structure variables for bird species richness and examining their relative importance. We surveyed and mapped all individual birds in a 50-ha forest-farm landscape mosaic over three breeding seasons and recorded the vegetation in 286 patches of six land-use types. Native forests and conifer plantations (covering 59% of the area) contained 89% of the individuals and all of the bird species recorded. The effects of vegetation structure variables, tree family richness, and foliage coverage were more significant than those of patch-structure variables. Although conifer plantations were low in tree family richness of the canopy layer, they had a high tree family richness in the sub-canopy layer, and had similar bird density and species richness values as native forests. Creating and maintaining patches with a complex vegetation structure are critical for supporting animal abundance and species diversity. Forest patches dominated by only a few tree species in the canopy layer can be greatly improved by increasing the floristic composition of the sub-canopy layer. Large patches with a complex vegetation structure are important for sustaining biodiversity and should be kept as intact as possible.

An Advanced Multiple‐Layer Canopy Model in the WRF Model With Large‐Eddy Simulations to Simulate Canopy Flows and Scalar Transport Under Different Stability Conditions

AbstractForest canopies play a critical role in affecting momentum and scalar transfer. Although there have been recent advances in numerical simulations of turbulent flows and scalar transfer across plant canopies and the atmosphere interface, few models have incorporated all important physical and physiological processes in subcanopy layers. Here we describe and evaluate an advanced multiple‐layer canopy module (MCANOPY), which is developed based largely on the Community Land Model version 4.5 and then coupled with the Weather Research and Forecasting model with large‐eddy simulations (WRF‐LES). The MCANOPY includes a suite of subcanopy processes, including radiation transfer, photosynthesis, canopy layer energy balance, momentum drag, and heat, water vapor, and CO2 exchange between canopy layers and the canopy atmosphere. Numerical schemes for heat and water transport in soil, ground surface energy balance, and soil respiration are also included. Both the stand‐alone MCANOPY and the coupled system (the WRF‐LES‐MCANOPY) are evaluated against data measured in the Canopy Horizontal Array Turbulence Study field experiment. The MCANOPY performs reasonably well in reproducing vertical profiles of mean and turbulent flows as well as second‐order statistical quantities including heat and scalar fluxes within the canopy under unstable stability conditions. The coupled WRF‐LES‐MCANOPY captures major features of canopy edge flows under both neutral and unstable conditions. Limitations of the MCANOPY are discussed for our further work. Our results suggest that our model can be a promising modeling system for a variety of applications to study canopy flows and scalar transport (e.g., CO2).

EFFECTS OF CANOPY STRUCTURE ON GROWTH AND BELOWGROUND/ABOVEGROUND BIOMASS OF SEEDLINGS IN UNEVEN-AGED TROJAN FIR STANDS

ABSTRACT Growth and survival of understory seedlings are influenced by their interactions with the environmental variables. The understanding of the relationships between stand density, canopy structure, and understory seedlings’ growth help forest managers conduct successful establishment through natural regeneration. In this study, the influence of stand basal area (BA) (m2.ha-1), photosynthetically active radiation transmitted through canopy (PART), leaf area index (LAI), height-to-crown base (HCB) and aspect on the root-collar diameter (RCD) (mm) growth, height growth (cm) and belowground/aboveground biomass (g) of seedlings is observed in uneven-aged Trojan fir stands. Seedling growth and belowground/aboveground biomass models were developed for five growing seasons after germination. PART, aspect and HCB were found to be the most strongly related to RCD and height growth of Trojan fir seedlings. PART and aspect explained the most variance in belowground/aboveground biomass of the seedlings. The data also showed that the light transmitted through the canopy was the most significant predictor of understory seedlings growth; thus, PART reaching understory can accelerate the development of sub-canopy layers in uneven-aged Trojan fir stands. Although survival of Trojan fir seedlings is usually high under canopy, results suggest that complete canopy closure should be avoided even in stands of shade-tolerant species such as Trojan fir to increase a seedling’s vigor for its successful recruitment into middle and overstory. The findings of this study will be helpful for forest managers to enhance the establishment and recruitment of Trojan fir seedlings in uneven-aged stands.

Diversity-biomass relationship across forest layers: implications for niche complementarity and selection effects.

Forest stratification plays a crucial role in light interception and plant photosynthetic activities. However, despite the increased number of studies on biodiversity-ecosystem function, we still lack information on how stratification in tropical forests modulates biodiversity effects. Moreover, there is less investigation and argument on the role of species and functional traits in forest layers. Here, we analysed from a perspective of forest layer (sub-canopy, canopy and emergent species layers), the relationship between diversity and aboveground biomass (AGB), focusing on functional diversity and dominance, and underlying mechanisms such as niche complementarity and selection. The sub-canopy layer had the highest species richness and diversity, while the emergent layer had the highest AGB. Species richness-AGB relationship was positive for each forest layer, but stronger for sub-canopy layer than for canopy and emergent layers. Total AGB was strongly correlated with functional diversity, leaf and wood traits of species in the sub-canopy and canopy layers. This suggests that sub-canopy and canopy species are major drivers of stand diversity-AGB relationship, and that resource filtering by canopy or emergent trees may not reduce the strength of diversity-AGB relationship in the sub-canopy layer. We argue that complementary resource use by sub-canopy species that supports niche complementarity, is a key mechanism driving AGB in natural forests. Selection effects are most evident in emergent species and niche complementarity effects for sub-canopy and canopy species, supporting arguments that AGB is affected by sub-canopy species' efficient use of limited resources despite competition from emergent species.

钱江源国家公园古田山常绿阔叶林木本植物的萌生更新特征

PDF HTML阅读 XML下载 导出引用 引用提醒 钱江源国家公园古田山常绿阔叶林木本植物的萌生更新特征 DOI: 10.5846/stxb201704120641 作者: 作者单位: 浙江师范大学化学与生命科学学院,钱江源国家公园生态资源保护中心,浙江师范大学化学与生命科学学院,浙江师范大学化学与生命科学学院,浙江师范大学化学与生命科学学院,钱江源国家公园生态资源保护中心,浙江师范大学化学与生命科学学院,浙江师范大学化学与生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 浙江省自然科学基金项目（LY17C030001）；国家自然科学基金面上项目（41471049） Sprouting characteristics of woody species in a subtropical evergreen broad-leaved forest in Gutianshan of Qianjiangyuan National Park, East China Author: Affiliation: College of Chemistry and Life Sciences,Zhejiang Normal University,Jinhua,,College of Chemistry and Life Sciences,Zhejiang Normal University,Jinhua,College of Chemistry and Life Sciences,Zhejiang Normal University,Jinhua,College of Chemistry and Life Sciences,Zhejiang Normal University,Jinhua,,College of Chemistry and Life Sciences,Zhejiang Normal University,Jinhua,College of Chemistry and Life Sciences, Zhejiang Normal 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:萌生更新是木本植物在原位进行更新的有效手段，使群落具有较强的恢复力。但以往研究侧重于实生更新，森林中木本植物的萌生更新特征及其在森林群落中的地位仍未得到足够理解。基于钱江源国家公园古田山国家级自然保护区内5 hm2亚热带常绿阔叶林样地的群落数据，分析木本植物萌生更新的数量特征，同时对不同分类单元、不同功能类群的萌生能力等进行比较。结果表明：（1）样地内64%的物种、20%的实生个体已经发生萌生更新现象，且萌生茎的数量占样地总个体数量的24%；（2）物种水平与科水平上，萌生能力均表现为显著差异（F=13.11，P < 0.001；F=27.45，P < 0.001）。腺蜡瓣花、柳叶蜡梅、宜昌荚蒾、窄基红褐柃、美丽马醉木等物种的萌生能力较强，蜡梅科、忍冬科、木兰科、壳斗科等类群的萌生能力较强；（3）不同垂直结构层次（林冠层、亚乔木层、灌木层）的萌生能力差异显著（F=117.5，P < 0.001），灌木层物种的萌生能力是林冠层与亚乔木层的1倍左右。不同生活型（常绿组分与落叶组分）的萌生能力差异显著，常绿类群的萌生能力显著高于落叶类群（P < 0.001）。萌生更新在亚热带常绿阔叶林中具有重要地位，可能是物种多样性维持、群落更新与演替的机制之一。灌木物种与常绿物种有着较强的萌生能力，暗示着萌生可能是植物适应荫蔽环境的生态策略之一。 Abstract:Sprouting, an effective means of regeneration in woody plants, gives the forest community a great resilience. However, most previous studies focused on seedling regeneration, so the importance of sprouting regeneration in forests are still not well understood. Using a 5 hm2 plot of subtropical evergreen broad-leaved forest in Gutianshan National Nature Reserve of Qianjiangyuan National Park, we quantitatively analyzed the characteristics of sprouting in woody plants, and the variations of the sprouting abilities of different taxa and different functional groups. Results showed that:(1) 64% of species and 20% of individuals had sprouted, and sprouted stems accounted for 24% of the total individuals in the plot. (2) There were significant differences in sprouting ability both on the species level and on the family level (F=13.11, P < 0.001; F=27.45, P < 0.001). More precisely, the species Corylopsis glandulifera, Chimonanthus salicifolius, Viburnum erosum, Eurya rubiginosa var. attenuata, and Pieris formosa, and those in Calycanthaceae, Caprifoliaceae, Magnoliaceae, and Fagaceae had high sprouting abilities. (3) There were significant differences among different vertical structure layers in sprouting ability (F=117.5, P < 0.001), and the sprouting abilities of species in the shrub layer were about twice those in the canopy layer and sub-canopy layer. Significant differences in sprouting ability were also detected between different life forms (evergreen vs. deciduous), where the sprouting ability in evergreen groups was higher than that in deciduous groups (P < 0.001). Sprouting regeneration plays an important role in subtropical evergreen broad-leaved forest and may be one of the mechanisms related to species diversity maintenance and community succession. Shrub species and evergreen species have strong sprouting ability, implying that sprouting may be a plant strategy for shade tolerance. 参考文献 相似文献 引证文献

Mapping the height and spatial cover of features beneath the forest canopy at small-scales using airborne scanning discrete return Lidar

The objective of the current study was to develop methods for estimating the height and horizontal coverage of the forest understorey using airborne Lidar data in three managed pine plantation forest typical of the south eastern USA. The current project demonstrates a two-step approach applied automatically across a given study site extent. The first operation divided the study site extent into a regularly spaced grid (25 × 25 m) and identified the potential height range of the main Loblolly pine canopy layer for each grid-cell through aggregating Lidar return height measurements into a ‘stack’ of vertical height bins describing the frequency of returns by height. Once height bins were created, the resulting vertical distributions were smoothed with a regression curve line function and the main canopy vertical layer was identified through the detection of local maxima and minima. The second operation sub-divided the 25 × 25 m grid-cell into 1 × 1 m horizontal grid, for which height-bin stacks were created for each cell. Vertical features below the main canopy were then identified at this scale in the same manner as in the previous step, and classified as understorey features if they were lower in height than the 25 × 25 m estimate of the main canopy layer. The heights of the tallest understorey and sub-canopy layers were kept, and used to produce a rasterized map of the understorey layer height at the 1 × 1 m scale. Lidar derived estimates of the 25 × 25 m lowest vertical extent of the coniferous canopy correlated highly with field data (R2 0.87; RMSE 2.1 m). Estimates of understorey horizontal cover ranged from R2 0.80 to 0.90 (RMSE 6.6–11.7%), and maximum understorey layer height ranged from R2 0.69 to 0.80 (RMSE 1.6–3.4 m) for the three study sites. The automated method deployed within the current study proved sufficient in determining the presence and absence of vegetation and artificial structures within the understorey portion of the current forest context, in addition to height and horizontal cover to a reasonable accuracy. Issues were encountered within older stands (e.g. more than 30 years old) where understorey deciduous vegetation layers intersected with the coniferous canopy layer, resulting in an underestimation of sub-dominant heights.

Conservation and development in conflict: regeneration of wildDavidia involucrata(Nyssaceae) communities weakened by bamboo management in south-central China

AbstractProtected areas, including nature reserves and management areas, are established for the conservation of biological diversity and protection of the associated natural and cultural resources. These objectives, however, are often in conflict with socio-economic development. We investigated the plant communities dominated by the dove treeDavidia involucratain a nature reserve on Mount Jinfo, China, where people intensively manage large areas of bamboo stands. We found a significant lack of small-sized main stems ofD.involucrata(0–25 cm diameter at breast height; height &gt; 1.3 m) and newly emerging sprouts in the reserve. The height-class distribution showed a unimodal pattern, with most individuals (of bothD.involucrataand co-occurring species) concentrated in the 16–28 m height-class, and few individuals in the shrub and sub-canopy layer (1.3–8 m). Existing practices to facilitate the spread of bamboo stands, and the need to develop a local market for bamboo shoots received little consideration when the nature reserve was established in 1979 to protectD.involucrata. To conserveD. involucrataon Mount Jinfo the appropriate authorities and local parties involved in bamboo harvesting need to focus on methods that are favourable to the life history of this and other tree species, and strategies for their regeneration. These methods will also benefit the conservation of other highly valued trees that share similar life-history characteristics withD. involucrata.

Time series data of a broadleaved secondary forest in Japan as affected by deer and mass mortality of oak trees.

BackgroundAbandonment of broadleaved secondary forests that have been used for various purposes may cause the loss of biodiversity. Some of these forests suffer from diseases such as Japanese oak wilt. An increasing number of deer also impact some of them. Monitoring and recording the status of such forests is important for their proper management.New informationThis data set provides a concrete example of temporal changes in a temperate broadleaved secondary forest. The forest has been damaged by mass mortality of oak trees caused by Japanese oak wilt disease. In addition, the forest has been under foraging pressure by sika deer (Cervus nippon Temminck). The data set can provide information on how such a forest has changed in species composition of the canopy and sub-canopy layers and in species occurrence in the understory layer.

Sprucing up the mixedwoods: growth response of white spruce (Picea glauca) to partial cutting in the eastern Canadian boreal forest

Mixed-species stands present a number of opportunities for and challenges to forest managers. Boreal mixedwood stands in eastern Canada are often characterized by a dominant canopy of shade-intolerant aspen (Populus tremuloides Michx.) with more shade-tolerant conifers in the mid- to sub-canopy layers. Because the aspen and conifer components often attain optimal merchantable sizes at different moments in stand development, there is an interest in developing silvicultural practices that allow partial or total removal of aspen and favour accelerated growth of residual conifers. We tested four partial harvesting treatments in mixed aspen – white spruce (Picea glauca (Moench.) Voss) stands in which different proportions of aspen (0%, 50%, 65%, and 100% basal area) were removed. Ten years after treatments, 72 spruce stems representing dominant, co-dominant, and suppressed social classes were destructively sampled for stem analysis. Using linear mixed effect models, we analyzed growth as a function of treatment intensity, time since treatment, social status, pretreatment growth rate, and neighbourhood competition. Relative to control stands, radial and volume growth responses were detected only in the extreme treatment of 100% aspen removal. In relative terms, suppressed trees showed the greatest magnitude of cumulative growth increase. Compared with control trees, average annual radial and volume increments were, respectively, 23.5% and 7.1% higher for dominant trees, 67.7% and 24.1% higher for co-dominant trees, and 115.8% and 65.6% higher for suppressed trees over the 10 years after treatment. Growth response was proportional to pretreatment growth rate, and among neighbouring trees, only coniferous neighbours had a negative effect on white spruce growth. Our results suggest that in similar mixed-stand conditions, relatively heavy removal of overstory aspen accompanied by thinning of crowded conifers would result in greatest growth response of residual spruce stems.

Thirty Years of Compositional Change in an Old-Growth Temperate Forest: The Role of Topographic Gradients in Oak-Maple Dynamics.

Ecological communities are structured in response to spatial and temporal variation of numerous factors, including edaphic conditions, biotic interactions, climatic patterns and disturbance regimes. Widespread anthropogenic factors such as timber harvesting can create long-lasting impacts, obscuring the relationship between community structure and environmental conditions. Minimally impacted systems such as old-growth forests can serve as a useful ecological baseline for predicting long-term compositional shifts. We utilized decadal tree species sampling data (1979–2010) divided into three strata (understory, midstory, overstory) to examine temporal changes in relative abundances and spatial distributions of dominant taxa, as well as overall shifts in community composition, in a relatively pristine Appalachian old-growth forest in eastern Kentucky, USA. Quercus and Carya species persisted mainly as mature canopy trees with decreasing juvenile recruitment, especially in mesic areas. In contrast, Acer, Fagus, and other mesophytic species were abundant and spatially widespread in subcanopy layers suggesting these species are more likely to recruit in gap-scale canopy openings. In the overstory, mesophytic species were spatially restricted to lower and mid-slope mesic habitats. Temporal changes in community composition were most evident in the understory and tended to be greater in mesic areas, a trend seemingly driven by recruitment failure among xerophytic species. In subcanopy vegetation we discovered a loss of distinction through time among the ecological community designations established following the 1979 survey (Chestnut oak, Mixed mesophytic, and Beech). The overstory was more stable through time, suggesting a storage effect where long-lived trees have maintained a particular community composition through time in areas where regeneration opportunities are minimal under current environmental conditions. Overall, sitewide canopy succession is occurring slowly in the absence of major disturbance, and topography-driven environmental variation appears to have an important local-scale filtering effect on communities.