Deciduous Broad-leaved Species Research Articles

Functional diversity of neighbours mediates sap flow density and radial growth of focal trees, but in different ways between evergreen and deciduous broadleaved species

Abstract The functioning of a tree is shaped by the neighbouring species through the interspecific interaction and local environments. The functional trait composition of the neighbourhood could provide mechanistic insights into the effects of neighbours on the resource strategies of focal trees. In this study, we deployed an automated high‐frequency measurement of the sap flow density (SFD) and the radial growth of 48 trees of 12 species at BEF‐China, a large‐scale forest biodiversity manipulation experiment, to investigate the consequences and underlying mechanisms of the functional trait composition of the neighbourhood on the sap flow and radial growth of focal trees. We found a positive relationship between SFD and growth, reflecting the important supportive role of sap flow in tree growth. High functional diversity (FD) of the neighbourhood depressed SFD but promoted growth when considering all species, and thus promoted water‐use efficiency. Acquisitiveness of neighbouring trees positively affected growth, suggesting interspecific facilitation. Furthermore, neighbourhood FD benefits evergreen focal trees by promoting growth. However, in deciduous focal trees, neighbourhood FD reduced SFD but had no significant effects on growth. Our findings suggest that considering the functional trait composition of neighbourhood communities will support effective afforestation and forest management. Read the free Plain Language Summary for this article on the Journal blog.

The Added Value of Urban Trees (Tilia tomentosa Moench, Fraxinus excelsior L. and Pinus nigra J.F. Arnold) in Terms of Air Pollutant Removal

The serious densification of human settlements necessitates an increase in the role and importance of green infrastructures in the overall functioning of urban ecosystems. Accordingly, the aim of the present study was to (1) assess the efficiency of air pollutant removal (potentially toxic elements) of three common ornamental trees (Tilia tomentosa Moench, Fraxinus excelsior L. and Pinus nigra J.F. Arnold) and (2) model the air quality regulatory services (removal of PM10, PM2.5 and NO2). Three different approaches were applied—enrichment factor (EF) and metal accumulation factor (MAI) per tree species, as well as simulation modeling for the whole urban forest. The MAI values of the three studied species were found to be very similar, in the range of 22.35 to 23.08, which suggests that these species could be a good choice for planting in urban areas with worsened air quality. The highest EF values were observed for U (3–18), followed by As (1.6–2.56) and Sr (0.87–2.46). The potential of urban forests in countering air pollution was highlighted by three simulated scenarios for PM10, PM2.5 and NO2 removal. The highest removal efficiency was calculated for evergreen species, followed by the mixed composition of deciduous (90%) and evergreen trees (10%), and the scenario with wholly deciduous trees had the lowest one. The contribution of nature-based solutions in meeting air quality standards and enhancing resilience in urban areas was clearly demonstrated. The functional complementarity of the different functional tree groups (coniferous, evergreen and deciduous broad-leaved species) was proven to be crucial for the support of both functional stabilities of the phytocenosis under diverse climatic conditions and during the change of seasonal cycles in the vegetation.

Restoring Subtropical Forests: Alleviating P Limitation and Introducing C Limitation Using Evergreen Broad-Leaved Tree Species

Determining which species to utilize for the artificial restoration of subtropical secondary forests has become a focal point in forestry and ecology. To compare the effects of the subtropical secondary forest artificial restoration model on soil microbial nutrient acquisition and limitation, we examined secondary forests (CKs), evergreen coniferous forests (GCPs), evergreen coniferous mixed broad-leaved forests (GCBMs), evergreen mixed broad-leaved forests (GBMs), and natural deciduous broad-leaved mixed forests (DBMs) as research subjects. Among them, GCPs, GCBMs, and GBMs were dominated by the species of the early, middle, and climax stages of subtropical forest succession, respectively. The activities and stoichiometry of β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (ACP) in the topsoil were analyzed. The results showed that the forest type significantly affects the activities of BG and LAP rather than NAG or ACP. The BG activity in DBMs was the lowest, while the LAP activity in CKs was significantly higher than that in plantations. Furthermore, the nutrient limitation of microbes was quantitatively analyzed by using the vector analysis of enzyme stoichiometry. The soil microbes in the study area were co-limited by C and P, and the nutrient limitation was in the order of C > P > N. Among the forests, the enzyme stoichiometric ratios in GCPs and DBMs were closest to 1:1:1. From CKs to GBMs, the microbial C limitation was increased, while the P limitation was decreased. The C limitation in DBMs was slightly lower than that in CKs. Overall, the P limitation in evergreen plantations was less than that in CKs. The soil bulk density, C/P, and N/P significantly influenced enzyme activities and stoichiometry. These results suggest that the artificial restoration of subtropical forests using evergreen species alleviated P limitation, while using deciduous broad-leaved species offered potential for alleviating microbial C limitation. Compared with evergreen broad-leaved species, employing pioneer and mid-successional or deciduous broad-leaved species can better achieve balanced microbial nutrient requirements.

Adsorption of particulate matter and uptake of metal and non-metal elements from PM in leaves of Pinus densiflora and Quercus acutissima: a comparative study

Trees can serve as effective biofilters of Particulate matter (PM) pollution, making them valuable for managing air pollution and promoting public health. Leaves of trees can reduce PM through absorption, adsorption, and fallout mechanisms, which are influenced by species-specific characteristics and environmental factors. Although several studies have explored the impact of various leaf characteristics on their ability to adsorb PM from field conditions, few have been conducted in controlled chambers to analyze the adsorption of PM on leaf surfaces and the uptake of metal and non-metal elements from PM on leaves. To fill these knowledge gaps, this study investigated the PM adsorption and leaf characteristics of two different tree species, Pinus densiflora (an evergreen coniferous species) and Quercus acutissima (a deciduous broad-leaved species) under controlled conditions in a PM exposure chamber with a target concentration of 300 μg m−3. The main aim of this study was to measure and compare the rate of PM component (metal and non-metal elements) uptake in two species and investigate the leaf characteristics that contribute to PM adsorption. We investigated the relationship between PM adsorption and physiolog, micro-morphology, and chemical properties of the leaf surface in two species. This study used a Pearson’s correlation analysis and a principal component analysis (PCA) to evaluate correlation between PM adsorption and leaf characteristics and uptake of metal/non-metal elements in PM on leaves. This result showed that leaf characteristics such as stomatal size, leaf roughness, and wax content played a crucial role in PM10 adsorption, while physiological factors like transpiration and leaf boundary layer conductance were identified as important determinants of PM2.5 adsorption on plant leaves. It also observed significant variations in the uptake of aluminum, iron, magnesium, phosphorus, and sulfur. This study not only advances our understanding of the mechanisms behind PM adsorption by tree leaves but also underscores the importance of selecting appropriate tree species based on their leaf characteristics for urban forestry and green infrastructure projects. The ability to strategically use tree species for PM pollution mitigation highlights a practical approach to enhancing environmental sustainability and public health.

Factors influencing the difference in dissolved ion inputs to the forest floor between deciduous and coniferous stands: comparison under high and low atmospheric deposition conditions

It is necessary to clear the relationship between physical and vegetation factors on the processes governing dissolved ion inputs to the forest floor to estimate correctly the values of atmospheric input to the forest. This study identified the factors influencing the differences in dissolved ion inputs to the forest floor between coniferous evergreen and broad-leaved deciduous species by analyzing the phenological variations of dry deposition and canopy exchange calculated by the canopy budget model under a high-deposition site near the city of Tokyo and a low-deposition site 84 km further away. At low-deposition site, vegetation factors such as capture efficiency did not explain the differences in Na+ or Cl− dry deposition. Leaf physiological characteristics influenced the differences in the Mg2+ and Ca2+ canopy leaching values, and phenology, leaf wettability, and diffusion processes from water film into leaves influenced the differences in NH4+ and NO3− input processes between tree types. At the high-deposition site, differences in the dry deposition of Na+, SO42−, Cl−, Mg2+, Ca2+, NH4+, and NO3− between tree types were influenced by differences in capture efficiency between coniferous and broad-leaved canopies in the leafed period and by the absence of leaves in deciduous species after leaf fall. These results indicated that atmospheric deposition affected the capture efficiency of coniferous trees for dry deposition and enhanced the difference of dissolved ion inputs to the forest floor between coniferous and deciduous species.

Mid-Term Effects of Fire on Soil Properties of North-East Mediterranean Ecosystems

Fire is a fundamental ecological process with a long history on Earth, determining the distribution of vegetation formations across the globe. Fire, however, does not only affect the vegetation but also the soil on which vegetation grows, creating a post-fire environment that differs significantly in terms of soil chemical and physical properties from the pre-fire environment. The duration of these alterations remains largely unknown and depends both on the vegetation condition and the fire characteristics. In the current study, we investigate the effect of fire on some chemical and physical properties 11 years after the event in four plant communities. Two of them constitute typical Mediterranean fire-prone plant communities, dominated by sclerophyllous Mediterranean shrubs, such as Quercus coccifera and Q. ilex, while the other two are not considered fire prone and are dominated by deciduous broadleaved species such as Q. petraea and Castanea sativa, respectively. The results indicate that fire affects the soil properties of the various communities in a different manner. Burned sites in the Q. coccifera community have a significantly lower concentration of organic matter, total nitrogen, and available magnesium. At the same time, they have a significantly higher concentration of sand particles and a lower concentration of clay particles. The effect of fire on the soil properties of the other three communities is less dramatic, with differences only in total phosphorus, organic matter, and total nitrogen. The results are discussed in relation to the site conditions and the post-fire regeneration of plant communities.

Drivers of the differentiation between broad-leaved trees and shrubs in the shift from evergreen to deciduous leaf habit in forests of eastern Asian subtropics

In eastern Asian subtropical forests, leaf habit shifts from evergreen to deciduous broad-leaved woody plants toward higher latitudes. This shift has been largely explained by the greater capacity of deciduous broad-leaved plants to respond to harsh climatic conditions (e.g., greater seasonality). The advantages of deciduous leaf habit over evergreen leaf habit in more seasonal climates have led us to hypothesize that leaf habits would shift in response to climate changes more conspicuously in forest canopy trees than in forest understory shrubs. Furthermore, we hypothesize that in the forests of the subtropics, plants at higher latitudes, regardless of growth form, would better tolerate seasonal harsh climates, and hence show less differentiation in leaf habit shift, compared to those at lower latitudes. To test these two hypotheses, we modelled the proportion of deciduous broad-leaved species and the incidence of deciduous and evergreen broad-leaved species in woody angiosperm species compositions of ten large-sized forest plots distributed in the Chinese subtropics. We found that the rate of leaf habit shift along a latitudinal gradient was higher in forest trees than in forest shrubs. We also found that the differentiation in leaf habit shift between trees and shrubs is greater at lower latitudes (i.e., warmer climates) than at higher latitudes (i.e., colder climates). These findings indicate that specialized forest plants are differentially affected by climate in distinct forest strata in a manner dependent on latitudinal distribution. These differences in forest plant response to changes in climate suggest that global climate warming will alter growth forms and geographical distributions and ranges of forests.

Competition and Facilitation Co-Regulate Spatial Patterns and Coexistence in a Coniferous and Broad-Leaved Mixed Forest Community in Zhejiang, China

Plant interactions have long been the subject of intense research and debate in ecology. Competition and facilitation are known to be the basic drivers of community structure, species coexistence, and forest succession dynamics; however, there remains a lack of understanding of how spatial patterns affect these in the mixed forest community of coniferous and broad-leaved species. In the present study, we studied the roles of competition and facilitation in a mixed forest community in the Zhejiang Province, China. For this, we divided plants measured at a study site according to the size of the diameter at breast height (DBH) into three levels of saplings as follows: saplings (1 cm ≤ DBH < 5 cm), juveniles (5 cm ≤ DBH < 15 cm), and adults (DBH ≥ 15 cm). We used the spatial point pattern method to explore the raw number, spatial distribution, and both intra- and inter-specific correlations of coniferous and broad-leaved species at these different diameter levels. The corresponding findings were as follows. First, the DBH and structure of coniferous and broad-leaved species were similar, showing a distinct distribution in an inverted “J” shape as the number of individuals with a particular diameter declined as DBH increased. Second, when all individuals of a similar diameter range were pooled, coniferous species were clustered at all size scales; however, in this situation, broad-leaved species (evergreen and deciduous) showed a clumped distribution at small scales, and this decreased as spatial scale increased. Third, there were small, but significant positive correlations between large-diameter trees and small-diameter trees of coniferous species and between evergreen broad-leaved species at different diameter levels; however, as the scale increased, the correlation diminished. On any scale, individual deciduous broad-leaved species at different diameter ranges did not have any significant correlation. Fourth, coniferous species had a strong competitive effect on broad-leaved species, and there was a weak promoting effect between deciduous and evergreen broad-leaved species as well. In summary, different tree species occupy similar living spaces, and through competition and facilitation, regulate the spatial pattern and community stability of coniferous and broad-leaved species in mixed forest communities.

Characterization of the complete chloroplast genome of Handroanthus chrysanthus (Bignoniaceae)

Handroanthus chrysanthus is a deciduous broadleaved species with ecological and medicinal value. Here, the complete chloroplast genome of H. chrysanthus is characterized to investigate its phylogenetic position in Bignoniaceae. The chloroplast genome is 159,437 bp in size with GC content of 38.1%, including a large single copy region of 85,659 bp, a small single copy region of 12,824 bp and a pair of inverted repeats of 30,477 bp. It encodes 132 genes, including 87 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Based on current available chloroplast genome sequences, the phylogenetic analysis indicated that H. chrysanthus is closely related to Tabebuia nodosa.

Assessment of the mixed coniferousbroadleaved forest canopy disturbance induced by typhoon Maysak (2020) using drone-borne images near Vladivostok, Russia

We assess the impact of typhoon Maysak (2020) on the canopy structure of mixed coniferous-broadleaved forests with Abies holophylla, Pinus koraiensis and a complex of deciduous broad-leaved species and secondary oak forests of Quercus mongolica. The study was conducted in the experimental forest of the Botanical Garden-Institute FEB RAS. We classified the natural forest vegetation of the study area, created a high-resolution vegetation map, and assessed the damage from typhoon Maysak remotely using the ultra-high resolution images, obtained with an unmanned aerial vehicle. We found that the largest number and area of canopy gaps are associated with the conditionally primary coniferous-broadleaved forests, where Abies holophylla and Pinus koraiensis form the main canopy layer. The smallest number and area of gaps relate to the secondary oak forests.

Tree Species Classification in a Temperate Mixed Mountain Forest Landscape Using Random Forest and Multiple Datasets

For monitoring protected forest landscapes over time it is essential to follow changes in tree species composition and forest dynamics. Data driven remote sensing methods provide valuable options if terrestrial approaches for forest inventories and monitoring activities cannot be applied efficiently due to restrictions or the size of the study area. We demonstrate how species can be detected at a single tree level utilizing a Random Forest (RF) model using the Black Forest National Park as an example of a Central European forest landscape with complex relief. The classes were European silver fir (Abies alba, AA), Norway spruce (Picea abies, PA), Scots pine (Pinus sylvestris, PS), European larch (Larix decidua including Larix kampferii, LD), Douglas fir (Pseudotsuga menziesii, PM), deciduous broadleaved species (DB) and standing dead trees (snags, WD). Based on a multi-temporal (leaf-on and leaf-off phenophase) and multi-spectral mosaic (R-G-B-NIR) with 10 cm spatial resolution, digital elevation models (DTM, DSM, CHM) with 40 cm spatial resolution and a LiDAR dataset with 25 pulses per m2, 126 variables were derived and used to train the RF algorithm with 1130 individual trees. The main objective was to determine a subset of meaningful variables for the RF model classification on four heterogeneous test sites. Using feature selection techniques, mainly passive optical variables from the leaf-off phenophase were considered due to their ability to differentiate between conifers and the two broader classes. An examination of the two phenological phases (using the difference of the respective NDVIs) is important to clearly distinguish deciduous trees from other classes including snags (WD). We also found that the variables of the first derivation of NIR and the tree metrics play a crucial role in discriminating PA und PS. With this unique set of variables some classes can be differentiated more reliably, especially LD and DB but also AA, PA and WD, whereas difficulties exist in identifying PM and PS. Overall, the non-parametric object-based approach has proved to be highly suitable for accurately detecting (OA: 89.5%) of the analyzed classes. Finally, the successful classification of complex 265 km2 study area substantiates our findings.

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.

Nitrogen and phosphorus resorption and stoichiometric characteristics of different tree species in a mid-subtropical common-garden, China.

To understand the nutrient use strategies of 11 tree species in a subtropical common-garden, we measured the specific leaf area, nitrogen (N) and phosphorus (P) resorption and stoichiometric characteristics of leaves in August 2019. The results showed that the specific leaf area, N and P concentrations in mature and senescent leaves of evergreen broadleaved (Lindera communis, Cinnamomum camphora, Schima superba, Castanopsis carlesii, Michelia macclurei and Elaeocarpus decipiens) and coniferous species (Cunninghamia lanceolata and Pinus massoniana) were lower than those of deciduous broadleaved species (Liquidambar formosana, Sapindus mukorossi and Liriodendron chinense). In contrast, C:N and C:P in mature leaves of evergreen broadleaved and coniferous species were significantly higher than those of deciduous broadleaved species. Except for C. carlesii, the N:P of all the species were lower than 14. Compared with other tree species, N and P resorption efficiencies of S. mukorossi were higher than 50% based on both mass and leaf area. Although P resorption efficiency of P. massoniana, C. lanceolata and C. camphora were higher than 50%, N and P resorption efficiency of M. macclurei were the lowest with only 15%-30%. In addition, specific leaf area of mature leaves was significantly positively correlated with N and P concentrations, but negatively correlated with C:N and C:P. In the common-garden, evergreen broadleaved species such as C. carlesii and L. communis, and coniferous species such as P. massoniana might belong to the slow investment species with lower specific leaf area, N and P concentrations, displaying relatively efficient in N and P resorption and utilization in comparison with other species. In contrast, deciduous broadleaved species such as S. mukoraiensis might be the fast investment species with low N and P use efficiency. Interestingly, tree species being restricted by N availability did not exhibit higher N resorption efficiency in the common-garden. Similarly, C. carlesii, the only P-restricted species here, did not exhibit higher P resorption efficiency. Our results provided scientific support for afforestation practice in the mid-subtropics.

Crown Structure Explains the Discrepancy in Leaf Phenology Metrics Derived from Ground- and UAV-Based Observations in a Japanese Cool Temperate Deciduous Forest

Unmanned aerial vehicles (UAV) provide a new platform for monitoring crown-level leaf phenology due to the ability to cover a vast area while offering branch-level image resolution. However, below-crown vegetation, e.g., understory vegetation, subcanopy trees, and the branches of neighboring trees, along with the multi-layered structure of the target crown may significantly reduce the accuracy of UAV-based estimates of crown leaf phenology. To test this hypothesis, we compared UAV-derived crown leaf phenology results against those based on ground observations at the individual tree scale for 19 deciduous broad-leaved species (55 individuals in total) characterized by different crown structures. The mean crown-level green chromatic coordinate derived from UAV images poorly explained inter- and intra-species variations in spring leaf phenology, most probably due to the consistently early leaf emergence in the below-crown vegetation. The start dates for leaf expansion and end dates for leaf falling could be estimated with an accuracy of <1-week when the influence of below-crown vegetation was removed from the UAV images through visual interpretation. However, a large discrepancy between the phenological metrics derived from UAV images and ground observations was still found for the end date of leaf expansion (EOE) and start date of leaf falling (SOF). Bayesian modeling revealed that the discrepancy for EOE increased as crown length and volume increased. The crown structure was not found to contribute to the discrepancy in SOF value. Our study provides evidence that crown structure is a pivotal factor to consider when using UAV photography to reliably estimate crown leaf phenology at the individual tree-scale.

Exploring the Influence of Biological Traits and Environmental Drivers on Water Use Variations across Contrasting Forests

Understanding species-specific water use patterns across contrasting sites and how sensitivity of responses to environmental variables changes for different species is critical for evaluating potential forest dynamics and land use changes under global change. To quantify water use patterns and the sensitivity of tree transpiration to environmental drivers among sites and species, sap flow and meteorological data sets from three contrasting climatic zones were combined and compared in this analysis. Agathis australis from NZHP site, Schima wallichii Choisy (native) and Acacia mangium Willd (exotic) from CHS site, Liquidamber formosana Hance, Quercus variabilis Blume and Quercus acutissima Carruth from CJGS site were the dominant trees chosen as our study species. Biological traits were collected to explain the underlying physiological mechanisms for water use variation. Results showed that the strongest environmental drivers of sap flow were photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and temperature across sites, indicating that the response of water use to abiotic drivers converged across sites. Water use magnitude was site specific, which was controlled by site characteristics, species composition and local weather conditions. The species with higher sap flow density (Fd) generally had greater stomatal conductance. Native deciduous broadleaved species had a higher Fd and faster response to stomatal regulation than that of native evergreen broadleaved species (S. wallichii) and conifer species A. australis. The analysis also showed that exotic species (A. mangium) consumed more water than native species (S. wallichii). Trees with diffuse porous and lower wood density had relatively higher Fd for angiosperms, suggesting that water use was regulated by physiological differences. Water use characteristics across sites are controlled by both external factors such as site-specific characteristics (local environmental conditions and species composition) and internal factors such as biological traits (xylem anatomy, root biomass and leaf area), which highlights the complexity of quantifying land water budgets for areas covered by different species.

天目山常绿阔叶林空间结构动态变化特征

PDF HTML阅读 XML下载 导出引用 引用提醒 天目山常绿阔叶林空间结构动态变化特征 DOI: 10.5846/stxb201912312841 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目（31870617） Analysis on spatial structure dynamic characteristics of evergreen broad-leaved forest in Tianmu Mountain Author: Affiliation: 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:采用固定样地重复监测的方法，2005-2015年每5年1次对天目山国家级自然保护区内1hm2常绿阔叶林固定样地进行3次样地调查，按优势度分析法确定群落优势树种，根据树种类别将优势树种分为常绿阔叶树种、常绿针叶树种和落叶阔叶树种3个优势树种组，利用聚集指数、树种多样性混交度和Hegyi竞争指数3个空间结构指数，分析群落和优势树种在2005-2015年期间的空间结构动态变化特征。结果表明：（1）群落表现为低度聚集、中度混交和中度竞争状态。群落聚集程度和竞争强度降低，混交程度保持稳定。群落空间结构动态变化总体特征是混交度稳定性最高，其次是分布格局，竞争态势稳定性最低。（2）群落优势种组成变化不大，3个优势树种组均呈低度聚集分布；常绿阔叶树种表现为低度混交、中度竞争状态；常绿针叶和落叶阔叶树种均表现为中度混交、低度竞争状态。常绿阔叶树种的聚集程度和竞争强度降低，混交程度保持稳定，与群落空间结构动态变化特征基本一致。常绿针叶和落叶阔叶树种的3种空间结构均保持稳定。在常绿阔叶林经营或人工林近自然改造过程中，应重视群落和优势树种的空间结构变化规律，确定阶段性空间结构优化目标，逐步促进群落进展演替。 Abstract:In order to analyze the spatial structure dynamic characteristics of the evergreen broad-leaved forest in Tianmu Mountain, a permanent sample plot (1 hm2) in Tianmu Mountain National Nature Reserve was surveyed every 5 years from 2005 to 2015. Based on the filed data collected from these three surveys, dominance index analysis was applied to determine the dominant tree species. For easy analysis, the dominant tree species were divided into three dominant species groups: evergreen broad-leaved species, evergreen conifer species, and deciduous broad-leaved species. Then, spatial structure parameters such as aggregation index, tree species diversity mingling, Hegyi competition index were used to analyze the spatial structure dynamic characteristics of the whole community and dominant tree species during 2005-2015. The results showed that: (1) the spatial structure of community was characterized by low-level aggregation, moderate mingling and moderate competition. The degree of aggregation and competition decreased, whereas the mingling degree remained stable. And the dynamic change overall characteristics of community spatial structure were as follows: the stability of mingling degree was the highest, followed by distribution pattern, and competitive situation was the lowest. (2) The composition of dominant tree species in community did not change significantly. Three dominant species groups all represented a low-level aggregated distribution pattern. Furthermore, evergreen broad-leaved species showed a low degree of mingling and moderate competition. Both evergreen conifer species and deciduous broad-leaved species showed a moderate mingling degree and low-level competition. The spatial structure dynamic characteristics of evergreen broad-leaves species was that the degree of aggregation and competition decreased, and mingling degree remained stable. It was basically consistent with the spatial structure dynamic characteristics of community. But, the spatial structure of evergreen conifer species and deciduous broad-leaved species had remained stable from 2005 to 2015. During the management of evergreen broad-leaved forest or the close-to-nature transformation management of plantation, attention should be paid to the dynamic characteristic of spatial structure of community and dominant tree species and determine the staged spatial structure optimization goals to gradually promote community succession. At present, there are few studies on dynamic monitoring of evergreen broad-leaved forest spatial structure. In the future, the establishment of a permanent sample plot network of evergreen broad-leaved forest with spatial structure as the goal will play an important role in understanding the relationship between structure and function of evergreen broad-leaved forest, revealing the formation mechanism and succession law of community. 参考文献 相似文献 引证文献

Stoichiometry of carbon, nitrogen and phosphorus and their allometric relationship between leaves and fine roots of three functional tree seedlings.

We analyzed the contents and stoichiometric ratios of carbon (C), nitrogen (N) and phosphorus (P) in leaves and fine roots of Machilus pauhoi (an evergreen broad-leaved species), Cerasus campanulata (a deciduous broad-leaved species) and Fokienia hodginsii (an evergreen coniferous species) to compare the leaf and root stoichiometry and allometric relationship between different functional groups of trees. There were significant difference in the contents and stoichiometry of C, N and P in the leaves and fine roots among different functional groups. C content, C/N and C/P of the leaves and roots were the highest in M. pauhoi. N content and N/P of the leaves and roots were the highest in C. campanulata, whereas P content of the leaves and roots was the highest in F. hodginsii. The allometric relationship of C, N and P contents as well as their stoichiometric ratios between the leaves and fine roots showed significant difference, which was affected by functional difference. The allometric relationship between C/P and N/P with significantly different allometric indexes in leaves in seedlings of those three tree species, while the isometric relationship between the contents of N and P was found in fine roots. There were significant difference in the C, N and P stoichiometry between the leaves and fine roots. The allometric relationship between leaf C content and root P content in M. pauhoi was detected. C and N contents and C/N, N/P in leaves generally had the allometric or isokinetic relationships with C/N, N/P of fine roots. There were allometric relationships between the leaf C content and the root C, N and P contents in F. hodginsii. It was concluded that nutrient allocation between leaves and fine roots of C. campanulata was more strongly coordinated. The investment strategy of P for leaves and fine roots across those three tree species was similar. The results provided scientific reference for accurate nutrient management at seedling stage and efficient cultivation technique.

Intraspecific variation in spring leaf phenology and duration of leaf expansion in relation to leaf habit and leaf size of temperate tree species

Spring leaf phenology has been intensively studied in temperate deciduous broad-leaved tree species, but the phenology of evergreen broad-leaved tree species has seldom been focused on. Evaluation of the difference in spring leaf phenology between coexisting deciduous and evergreen species is essential to predict their responses to climate change. In this study, spring leaf phenology was investigated for the 12 deciduous and 12 evergreen broad-leaved species coexisting in a warm-temperate forest in Japan, based on the predictions that selection pressure for earlier leaf production in spring results in less intraspecific variation in phenology at a given timing (SDmax) and a shorter duration of leaf expansion in deciduous than in evergreen species. In contrast to this prediction, SDmax did not differ between deciduous and evergreen species and was not related to leaf area or LMA. On the other hand, the duration of leaf expansion was longer in evergreen than in deciduous species, and was positively correlated with LMA. The leaves of greater LMA required longer periods of leaf expansion, probably due to a higher cost of and/or more conservative leaf development in the face of herbivory. As a consequence, the timing of full leaf expansion was delayed not only by later budburst (approximately two weeks) but also by a longer duration of leaf expansion (approximately two weeks) in evergreen than in deciduous broad-leaved species, which would probably influence the productivity of newly emerging leaves in spring.

Sap flow characteristics in growing and non-growing seasons in three tree species in the semiarid Loess Plateau region of China

Year-round observation suggests that sap flow in growing season represents species-specific transpiration characteristics and sap flow of deciduous broadleaved species in non-growing season is related to daily changes in stem diameter. Year-round observation is necessary to investigate species-specific characteristics of sap flow and its possible contribution in non-growing season. The middle Loess Plateau in China is characterized by temperate climate and vegetation cover of generally drought-tolerant deciduous broadleaved and some evergreen coniferous trees. In this study, Granier-type thermal dissipation probes were applied to measure year-round xylem sap flow in three species from April 2017 to April 2018. Solar radiation, air temperature, relative air humidity, precipitation, and soil moisture were monitored continuously. The results showed that the peak time of sap flux density (Fd) in the diurnal courses of Robinia pseudoacacia was later than that of Quercus liaotungensis and Platycladus orientalis. The peak time of Fd for R. pseudoacacia was significantly postponed during the period with higher soil moisture when compared with that at lower soil moisture, whereas the peak time was reached slightly earlier in the other two species. Sap flow during the non-growing season was relatively higher in P. orientalis than in the two broadleaved species. The diurnal course of Fd in non-growing season showed high values at nighttime and low values in daytime, opposite to that in growing season. Daily variation in stem diameter was inverse of the change in sap flow in the two broadleaved species, whereas the daily change in stem diameter of P. orientalis was very small and showed no clear relation with sap flow. The results suggest that changes in transpiration characteristics with soil moisture conditions vary with tree species; sap flow in deciduous broadleaved trees in non-growing season is small and closely related to daily changes in stem diameter.

Evaluation of O3 Effects on Cumulative Photosynthetic CO2 Uptake in Seedlings of Four Japanese Deciduous Broad-Leaved Forest Tree Species Based on Stomatal O3 Uptake

The current level of tropospheric ozone (O3) is expected to reduce the net primary production of forest trees. Here, we evaluated the negative effects of O3 on the photosynthetic CO2 uptake of Japanese forest trees species based on their cumulative stomatal O3 uptake, defined as the phytotoxic O3 dose (POD). Seedlings of four representative Japanese deciduous broad-leaved forest tree species (Fagus crenata, Quercus serrata, Quercus mongolica var. crispula and Betula platyphylla var. japonica) were exposed to different O3 concentrations in open-top chambers for two growing seasons. The photosynthesis–light response curves (A-light curves) and stomatal conductance were measured to estimate the leaf-level cumulative photosynthetic CO2 uptake (ΣPn_est) and POD, respectively. The whole-plant-level ΣPn_est were highly correlated with the whole-plant dry mass increments over the two growing seasons. Because whole-plant growth is largely determined by the amount of leaf area per plant and net photosynthetic rate per leaf area, this result suggests that leaf-level ΣPn_est, which was estimated from the monthly A-light curves and hourly PPFD, could reflect the cumulative photosynthetic CO2 uptake of the seedlings per unit leaf area. Although the O3-induced reductions in the leaf-level ΣPn_est were well explained by POD in all four tree species, species-specific responses of leaf-level ΣPn_est to POD were observed. In addition, the flux threshold appropriate for the linear regression of the responses of relative leaf-level ΣPn_est to POD was also species-specific. Therefore, species-specific responses of cumulative photosynthetic CO2 uptake to POD could be used to accurately evaluate O3 impact on the net primary production of deciduous broad-leaved trees.