Undergrowth Vegetation Research Articles

Scale effect of landscape characteristics on undergrowth vegetation variance with different ecological traits

Herbaceous understory vegetation plays a significant role in temperate forested ecosystems, with its diversity strongly dependent on both local and landscape conditions. However, the contribution of these factors across different spatial scales (e.g., scale effect) remains inadequately understood. The objective of this study was to determine the most important landscape and local characteristics influencing the species richness of the herb layer. We surveyed and sampled 53 sites in a mountainous forest within the Baihuashan National Nature Reserve of Beijing. Using generalized linear models, we investigated the simultaneous effect of local (e.g. tree density, average tree height, and cover of tree, shrub, and ground vegetation) and landscape (e.g. Area-weighted Mean Patch Size, Area-weighted Mean Euclidean Nearest Neighbor Distance, Area-weighted Mean Fractal Dimension Index, forest area, and shrubbery area) variables on the richness of species in the understory herb layer. Variation partitioning was used to examine the individual contribution of local and landscape variables. Our results identified 366 plant species from 95 families across 53 sampling sites. Significant differences in species richness were found among life forms, seed dispersal types, and habitat preferences (P < 0.001). Parsimonious models indicated that combining local and landscape factors at a 2 km scale explained the most variation in phanerophytes (R2 = 0.658). Locally, average tree height significantly influenced the species richness of biotic dispersal, phanerophytes, and geophytes. At the landscape level, variables such as the Area-weighted Mean Fractal Dimension Index and farmland area significantly impacted plant community traits across different scales. Understanding these effects is crucial for developing effective sustainable forest ecosystem management strategies and for establishing robust ecological conservation policies.

Site occupancy of native terrestrial mammals in oil palm landscapes is driven by the synergy of land sparing and sharing strategies

The conversion of tropical rainforests into industrial oil palm monocultures has detrimental effects of local biodiversity. Although some medium-sized mammals have demonstrated a degree of adaptability in oil palm landscapes, the factors that influence their ability to persist in such human-altered environments remain obscure. Here, we investigated the site occupancy and activity pattern of the mammals in oil palm landscapes in Peninsular Malaysia. We deployed 81 camera traps throughout six oil palm cultivation areas with two distinct management styles (three sites each in organized smallholdings and industrial plantations). Smallholdings had higher site occupancy of native animal species than industrial plantations. The site occupancy of the mammals was influenced by the proximity to continuous forest, forest patches and riparian vegetation. Landscape metrics are characteristics that affect land sparing strategy, allowing wildanimals in agricultural landscapes to thrive in their habitat despite human threats. At stand-level, the detection of animals was determined by elevation, undergrowth vegetation cover/height, canopy cover, oil palm height, quantity of oil palm fruits, and prune stack thickness. Mammal occupancy was higher in the smallholdings due to the proximity to continuous forest. We recommend improving landscape heterogeneity and connectivity in oil palm matrix to promote species mobility and diversifying oil palm management away from monoculture farming. Our findings indicate that incorporating land sharing and sparing strategies into the oil palm matrix is necessary to conserve biodiversity and maintain ecological services. This implies that industry stakeholders ought not to disregard either land sparing or land sharing.

Ecological ramifications of marine debris in mangrove ecosystems: Estimation of substrate coverage and physical effects of marine debris on mangrove ecosystem in Negombo Lagoon, Sri Lanka

The adverse environmental impacts on mangrove ecosystems due to anthropogenic marine debris contamination have attracted public attention not only in Sri Lanka but worldwide. Therefore, quantification of marine debris in sensitive ecosystems like mangroves is critical to assess the impacts on ecosystem vitality and services. We conducted this study to assess the abundance and density of marine debris in Negombo lagoon, Western Province, Sri Lanka. We selected two sites (n = 2) using the purposive sampling technique. Marine debris cover and concentration were calculated to explore the extent of pollution from marine debris. The findings revealed that 9.83 ± 1.05 % of the substrate of the mangrove ecosystem is covered by debris. Nine types of marine debris were recorded, and a higher abundance belonged to single-use plastic items. A significantly higher debris cover was found in Kadolkele (18.80 ± 1.74 %, n = 120) than in Molekadolwetiya (0.85 ± 0.03 %, n = 120) (One-way ANOVA, p < 0.05). The study indicated that the mangroves in lagoon are highly polluted with marine debris and act as “litter catchers.” Correlation coefficient analysis was used to find the impact of debris cover on physical damage to roots, seedlings, and undergrowth vegetation. Correlation analysis revealed that physical damage to seedlings and branches/barks have a positive correlation with debris cover. To conserve these valuable coastal habitats in Negombo lagoon, it is recommended to take remedial measures to reduce arriving debris loads and to remove the debris present in mangroves.

SA-Pmnet: Utilizing Close-Range Photogrammetry Combined with Image Enhancement and Self-Attention Mechanisms for 3D Reconstruction of Forests

Efficient and precise forest surveys are crucial for in-depth understanding of the present state of forest resources and conducting scientific forest management. Close-range photogrammetry (CRP) technology enables the convenient and fast collection of highly overlapping sequential images, facilitating the reconstruction of 3D models of forest scenes, which significantly improves the efficiency of forest surveys and holds great potential for forestry visualization management. However, in practical forestry applications, CRP technology still presents challenges, such as low image quality and low reconstruction rates when dealing with complex undergrowth vegetation or forest terrain scenes. In this study, we utilized an iPad Pro device equipped with high-resolution cameras to collect sequential images of four plots in Gaofeng Forest Farm in Guangxi and Genhe Nature Reserve in Inner Mongolia, China. First, we compared the image enhancement effects of two algorithms: histogram equalization (HE) and median–Gaussian filtering (MG). Then, we proposed a deep learning network model called SA-Pmnet based on self-attention mechanisms for 3D reconstruction of forest scenes. The performance of the SA-Pmnet model was compared with that of the traditional SfM+MVS algorithm and the Patchmatchnet network model. The results show that histogram equalization significantly increases the number of matched feature points in the images and improves the uneven distribution of lighting. The deep learning networks demonstrate better performance in complex environmental forest scenes. The SA-Pmnet network, which employs self-attention mechanisms, improves the 3D reconstruction rate in the four plots to 94%, 92%, 94%, and 96% by capturing more details and achieves higher extraction accuracy of diameter at breast height (DBH) with values of 91.8%, 94.1%, 94.7%, and 91.2% respectively. These findings demonstrate the potential of combining of the image enhancement algorithm with deep learning models based on self-attention mechanisms for 3D reconstruction of forests, providing effective support for forest resource surveys and visualization management.

FOREST FEATURE LIDAR SLAM (F2-LSLAM) AND INTEGRATED SCAN SIMULTANEOUS TRAJECTORY ENHANCEMENT AND MAPPING (IS2-TEAM) FOR ACCURATE FOREST INVENTORY USING BACKPACK SYSTEMS

Abstract. Under-canopy mapping is desired to derive critical forest biometrics, such as diameter at breast height (DBH), merchantable height, and debris volume. The main challenge of such under-canopy mapping is the intermittent access to the global navigation satellite system (GNSS) signal, which is crucial to deriving accurately georeferenced mapping products. In this study, we propose two frameworks – Forest Feature LiDAR Simultaneous Localization and Mapping (F2-LSLAM) and Integrated Scan Simultaneous Trajectory Enhancement and mapping (IS2-TEAM) – for 3D LiDAR unit mounted on backpack systems to achieve accurate forest inventory. In the F2-LSLAM strategy, ground/tree trunk features are extracted from individual LiDAR scans. On the other hand, when trajectory information provided by navigation sensors is available, these semantic features are derived from LiDAR points within several scans (i.e., integrated scan) for the IS2-TEAM strategy. Then, local/global least squares adjustment (LSA) using derived features is performed to register LiDAR scans to a common reference frame for both strategies. To evaluate the performance of the proposed strategies, three in-house developed backpack systems with varying specifications were used to collect data in complicated forest environments. Through the comparison with point clouds acquired by a commercial backpack LiDAR system, the proposed frameworks are capable of generating point clouds with satisfactory intra-dataset alignment quality (in the range of 2–4 cm) for all backpack systems in natural forest areas with relatively flat terrain. However, for more challenging areas with dense undergrowth vegetation and/or large height differences, F2-LSLAM framework cannot extract sufficient features, while IS2-TEAM still exhibits good performance.

Developmental Dynamics and Driving Factors of Understory Vegetation: A Case Study of Three Typical Plantations in the Loess Plateau of China

Understory vegetation is one of the most important links for improving forest biodiversity, and its restoration is conducive to sustainable forest development, energy flow, and nutrient cycling. However, little is known about the developmental dynamics and main driving factors of the long-time series coverage, biomass, diversity, and species composition of plantation understory vegetation. In a case study of three typical plantations, with a natural secondary forest as reference in the Loess Plateau of China, we collected understory vegetation from a Robinia pseudoacacia Linn. deciduous broad-leaved plantation, Pinus tabulaeformis Carr. evergreen coniferous plantation, and mixed plantation with an age span of 10 to 50 years. (1) The understory plantation coverage and biomass results of stands with different ages showed the R. pseudoacacia plantation to be significantly higher than the P. tabulaeformis plantation, and the species diversity of the P. tabulaeformis plantation changed the most with the stand age. However, the growth resource imbalance, and drastic changes in the stands’ environment caused by excessive intraspecific competition in the early stage of the P. tabulaeformis plantation vegetation restoration, are the main reasons that make the species diversity of undergrowth vegetation of P. tabulaeformis plantation lower than that of other stand types. (2) The understory species composition of the plantations revealed their degree of community stability. Compared to the R. pseudoacacia plantation and P. tabulaeformis plantation, the mixed plantation had higher stability, and its species composition closely resembled a natural secondary forest. The community stability of the P. tabulaeformis plantation was the lowest because it had the lowest coverage, biomass, and species diversity of understory vegetation. However, the understory species composition of the three plantation types converged, which was due to atypical species contribution. (3) The dynamic changes of canopy and soil nutrients were the main driving factors affecting the R. pseudoacacia plantation understory vegetation species composition. Stand density and elevation limited the understory vegetation communities of P. tabulaeformis plantation restoration. Soil bulk density is the key factor affecting understory vegetation in mixed plantations, and this effect weakens with the stand age. In future studies, the focus should be on the converged action and further development trend of atypical species, choosing an appropriate recovery strategy (active or passive), and providing more possibilities for the intensive management of vegetation under different plantations.

Multi-species rotational grazing of small ruminants regenerates undergrowth vegetation while controlling weeds in the oil palm silvopastoral system

CONTEXT.Prolonged use of synthetic herbicides to control weeds may cause adverse effects on the environment and human wellbeing. As a mitigation effort, commercial oil palm growers have been encouraged to adopt livestock integration as a holistic approach to manage weeds. Previous studies have suggested utilizing a multi-species livestock grazing may optimize the grazing impacts in silvopastoral agroforestry systems. OBJECTIVEPresent study examined the effects of small ruminant grazing (i.e., goats, sheep and multi-species) on undergrowth vegetation with the following specific objectives: 1) to investigate the effects of small ruminant grazing treatments on undergrowth vegetation composition in oil palm plantations; 2) to examine the variables (canopy cover, grazing treatments, and cycles) that influenced undergrowth vegetation (species richness, coverage, height, and dry weight) in oil palm plantations. METHODSWe established quadrats on experimental plots to detect changes in undergrowth vegetation composition, species diversity, coverage, height, and dry weight resulting from different grazing treatments. RESULTS AND CONCLUSIONSWe found that undergrowth vegetation composition varied between different grazing treatments. The multi-species livestock grazing effectively supress unwanted weeds (i.e., woody broadleaves) compared to single–species livestock grazing (i.e., goats, sheep). The use of single-species livestock grazing is likely to cause oil palm growers to use herbicides to control undesirable weeds. Hence, we concluded managing undergrowth vegetation in oil palm plantations using multi-species livestock grazing is a practical approach, and it should be fine-tuned for example by choosing livestock species based on the targeted objectives and the grazing sequence that will be practiced to regenerate the oil palm silvopastoral system. SIGNIFICANCEMulti-species livestock grazing can reduce oil palm growers' dependence on synthetic herbicides for weed control and optimize land use in oil palm plantation sector. On the other hand, the use of single species, whether goat or sheep-only, has caused unwanted undergrowth to increase after several grazing rotations have been carried out. Therefore, the use of multi-species grazing is a promising biological tool to reduce synthetic herbicide application in environmentally-sustainable oil palm plantations.

Analisis Vegetasi Tumbuhan Bawah di Kawasan Geopark Silokek Kabupaten Sijunjung

Research on the analysis of undergrowth vegetation in the Silokek Geopark Area, Sijunjung Regency. This study aims to determine the composition and structure of the undergrowth in the Silokek Geopark Area, Sijunjung Regency. Vegetation analysis was carried out by using the transect method and purposive sampling by placing plots on the right and left of the transect, with a plot size of 2x2 m. There are 10 plots were created and species identification was carried out at the Andalas University Herbarium. Based on the results of the study, 12 families, 15 genera, 15 species, and 103 individuals were found with the dominant family being Poaceae and the co-dominant families Asteraceae, Schizaeceae, and Selaginellaceae. The highest important value index of Lygodium circinnatum is 30.79%. Understorey diversity index of 2.57. Based on the research, it can be concluded that the Poaceae family is able to reproduce well in this location and the diversity of understoreys is classified as moderate. It is recommended that local governments and local communities protect the biodiversity in this area.

Influences of Succession and Biogeoclimate on Forage Resources for Elk in Northern Idaho

Natural disturbance shaped forest communities for millennia, but fire suppression and timber harvest declines have altered forest structure across the western United States, reducing the abundance of forage for ungulates. We evaluated quality and quantity of forage resources for lactating elk (Cervus canadensis) and their calves in relation to season, succession, and biogeoclimate, the latter indexed by potential vegetation (PV) zones, across 36,500 km2 in Idaho's Clearwater and St. Joe River basins. In 0.2-ha macroplots (n = 359), we measured characteristics of forest overstory, biomass of current annual growth of undergrowth vegetation (kg ha-1), and nutritional content of these plants. Using biomass, digestible energy (kJ g-1), digestible protein (DP, g per100 g forage), and prior knowledge of elk diet selection and nutritional constraints, we developed 8 forage resource metrics. The greatest abundance of undergrowth vegetation (500 to 1,000 kg ha-1) occurred during the first 20 years after stand-replacing disturbance and declined as the overstory closed in wetter PV zones. Digestible energy decreased, whereas DP increased as stands aged. Evidence of nutritional limitations for lactating elk increased markedly after mid-summer; early-seral, high-elevation spruce–fir forests on productive soils provided the best opportunity for lactating elk to satisfy their requirements in late summer. Our findings demonstrate the importance of disturbance regimes that maintain early-seral communities in mosaics with mid- and late-seral stages, and suggest that implementing stand-replacing disturbance in relatively moist forest zones at mid and high elevations provides the greatest improvement in forage resources for lactating elk and their calves in summer.

The Effect of Changes in Forest Area Designation on a Diversity of Undergrowth Vegetation

Biodiversity is a term used for the degree of diversity of living natural resources, including the number and abundance of genes, species, and ecosystems in an area. Consists of various forms of life, their ecological role, and the diversity of germplasm contained therein. The purpose of this study was to examine the effect of changes in forest area designation on the diversity of understorey species. Data analysis used the method of placing plots in the lane using the plotted path method, with a plot area of 2 m x 2 m, by recording all understorey plants from sprouts to a seedling height of no more than 1.5 m. And also using the analysis of the important value index (INP) and species diversity. The results obtained from this study can be concluded that the species diversity in plantation forests is 3.470, in protected areas is 3.525 and in natural forests is 3.093. This shows that there is no serious effect on plant species diversity because the species diversity obtained shows results that are not much different between plantation forests, protected areas, and natural forests.

Effect of complete abolition of Eucalyptus species on under canopy species diversity in Gullele Botanic Garden, Ethiopia

Fast-growing, stress-tolerant tree species belonging to the genus Eucalyptus have historically been introduced in the central highlands of Ethiopia to support various economic and environment-regulating functions. While these non-native tree species are often highly useful, many are simultaneously invasive, generating negative environmental impacts and becoming the greatest global threat to biodiversity. This study is aimed at determining the impacts of the complete removal of the eucalyptus and its replacement by an indigenous species on the undergrowth vegetation of the Gulele Botanic Garden (GBG), Ethiopia. Vegetation data were collected from a total of 60 plots with a dimension of 20 m x 20 m that were laid out and equally distributed among invaded and indigenous species that dominate the landscape. Beside, diversity indices and population structural change parameters were employed for the comparison of changes. Results show that a total of 118 species (103 genera and 57 families) were recorded, and out of those, Eucalyptus camaldulensis was the most dominant species. On the other hand, the richest landscape (Juniperus procera plantation) contained 105 species and 51 families, whereas the poorest landscape (Eucalyptus plantation) was comprised of 66 species and 36 families. Furthermore, the alpha diversity index and vegetation vertical structure of the dominant Eucalyptus plantation differed significantly from those of other landscapes. Regeneration potential was not observed in Eucalyptus-dominant plantations since the inherent physiology of Eucalyptus species repels the regeneration of others. The population structure of the wood species showed an inverse-J curve. The total basal area (BA) of woody species decreased from 64.14 ± 1.54 m2 ha−1, 21.46 ± 0.54 m2 ha−1, and 17.18 m2 ha−1 ± 1.04 for Juniperus procera plantation, mixed plantation, and eucalyptus plantation, respectively. It was concluded that E. camaldulensis was one of the most dominant invasive species that reduced species diversity in the understory. While landscapes replaced after abolition by indigenous plantations demonstrated "fair" to "good" regeneration potential and an alpha diversity index.

Understanding the Impacts of Forest Management in Sal (Shorea robusta) Dominant Forest Stands in the Western Lowlands of Nepal

Sal (Shorea robusta) is an economically and ecologically important tree species found in Nepal. Since 2003, Nepal's government has been managing the Sal forest under the Scientific Forest Management (SciFM) scheme. Due to newly implemented approaches, the information regarding the Sal forest condition under regeneration felling and thinning is low. This study aimed to understand the regeneration status after regeneration felling and compare crop stands between thinned and unthinned plots. We selected three years of harvested, thinned, and unthinned blocks in the Tilaurakot collaborative forest. Vegetation sampling was carried out in 63 concentric circular plots. The results show that the number of seedlings and saplings in the harvested blocks was 14,000 and 3368 per hectare, respectively. The growing stock and basal area per hectare in the thinned blocks were lower than in the unthinned blocks. The numbers of trees and poles per hectare were lower in the thinned block than in the unthinned block. Sal's importance valve index (IVI) was higher than other species in all three block types. The study suggests that the regeneration condition was better after the canopy's opening, and thinning promotes the growth of trees and undergrowth vegetation.

Differential responses of soil arthropods to the application of biogas slurry and biochar in a coastal poplar plantation

As critical drivers of ecosystem functionality, soil fauna are sensitive to soil management such as organic amendments. However, the effects of organic amendments on soil fauna communities are poorly understood. Here, we evaluated the differentiated responses of soil arthropod communities to the application of biogas slurry (BS) and biochar (BC) in a newly established poplar plantation on reclaimed coastal land. Compared with the control, the application of BS increased the abundance of soil arthropods by 113–253%, whereas the application of BC decreased it by 35–74%. Furthermore, the total taxonomic richness and Shannon index of the soil arthropods increased under the BS treatments and decreased under a high-dose BC treatment. Arthropod abundance and diversity under the BS treatments correlated with the increased biomass (46–76%) of leaf litterfall, fine roots, and undergrowth vegetation, elevated soil water and nitrogen concentrations (28–254%), as well as neutralized soil pH. In contrast, arthropod abundance and diversity under the BC treatments were correlated with decreased fine root biomass and increased soil alkalinity. These results suggested that BS and BC applications exert different effects on arthropod communities, probably linked with the differential direction and extent of the modification on plant food resource and soil variables in the newly reclaimed coastal lands.

Analysis of the Eucalyptus Crown of Clone IND 72 and IND 83 Against the Composition of Undergrowth Vegetation in PT.Toba Pulp Lestari Tbk., Habinsaran Sector of Toba Regency

The purpose of the study was to identify the diversity of plant types under the Eucalyptus stand and analyze the percentage of cover titled Eucalyptus Clone IND 72 and 83 against the composition of the undergrowth vegetation species in the Habinsaran sector of Toba Regency.Plot determination is done using the minimum species curve method, so that the number of PLOTS IND 72 as many as 29 plots, and IND 83 as many as 28 plots.The data taken is data on the vegetation of the undergrowth vegetatioin the form of the number and type of undergrowth vegetatio, as well as header cover data, then analyzed by calculating density, frequency, INP, and Similarity Index. There are 10 types of lower plants located in the Habinsaran Sector TPL Plant Forest of Toba Samosir Regency.The dominance of the undergrowth vegetation of each clone is occupied by boreria sp type with Important Value Index (INP) on the Stands of Eucalyptus Clone IND 72 = 67.19, and Stands Eucalyptus Clone IND 83 = 57.68.In the stands of Eucalyptus Clone IND 72 obtained a percentage of headers of 1.70% (&lt;50%) including the category of small header cover, with a composition of undergrowth vegetation as many as 9 types, with an average density of 128.9 / ha.On the stand of Eucalytus Clone IND 83 obtained a percentage of headers of 1.80% (&lt;50%) including the category of small header cover, with a undergrowth vegetation as many as 10 types, with an average density of 104.6/ha.

The Composition of Undergrowth Vegetation in Forest Area with the Special Purpose of Gunung Bromo, Karangayar, Central Java, Indonesia

Data on the biodiversity is essential to support the Forest Area with the Special Purpose (KHDTK) of Gunung Bromo as an educational forest and training center. This study aimed to obtain basic information on undergrowth vegetation composition under pine stands. Furthermore, the important value index (IVI), species diversity index (H’), species richness index (R), and evenness index (E) were determined. The data was systematically obtained by marking 35 plots of 2 m × 2 m. The distance between plots was 100 m. The results showed that the undergrowth vegetation consisted of 39 species from 26 families. The habitus of undergrowth vegetation was herb (15 species), shrub (14 species), liana (3 species), fern (6 species), and palm (1 species). Eragrostis tenerum was the dominant species with an IVI of 58.84%). Centrosema pubescens showed an IVI of 18.38%, while the other species showed less than 10%. Furthermore, H’ was classified as moderate (2.35), R was classified as moderate (4.69), and E was classified as uneven (0.64). This condition indicated that the undergrowth species that grew in KHDTK of Gunung Bromo was limited and uneven. It was considered due to inhibiting factors such as allelopathy in pine leaf litter and low light intensity. Undergrowth species that grow in KHDTK of Gunung Bromo showed several potential utilizations, such as medicinal plants (30 species), ornamental plants (9 species), food sources (5 species), forage (4 species), culture and crafts (4 species), and conservation (3 species). Keywords: important value index, KHDTK of Gunung Bromo, species composition, species diversity, undergrowth vegetation

The Effects of Different Undergrowth Vegetation on the Types and Densities of Functional Ground-Dwelling Arthropods in Citrus Orchards

&lt;p&gt;In agricultural lands, citrus orchards, pest feeding and weed seed predation by ground-dwelling arthropods are essential ecosystem services. This research aims to investigate the effects of different undergrowth vegetation, including weed area, bare land, rattail fescue and white clover fields, on the types and densities of functional ground-dwelling arthropods in citrus orchards, using pitfall traps. The captured organisms included carnivorous beetles (&lt;em&gt;Pheropsophus jessoensis&lt;/em&gt;,&lt;em&gt; Chlaenius naeviger&lt;/em&gt; and &lt;em&gt;Dolichus halensis&lt;/em&gt;), wolf spiders (&lt;em&gt;Lycosidae&lt;/em&gt; sp.), earwigs (&lt;em&gt;Anisolabididae&lt;/em&gt; sp.), house centipedes (&lt;em&gt;Scutigeromorpha&lt;/em&gt; sp.), herbivorous ground beetles (&lt;em&gt;Amara&lt;/em&gt; sp., &lt;em&gt;Harpalinae&lt;/em&gt; sp.), crickets and millipedes. Furthermore, the population of the functional ground-dwelling arthropods was significantly increased by the presence of a live mulch, where a higher number was seen in the rattail fescue or white clover compared to the weed or bare land fields. The cover crops also affected the types of arthropods identified, with the rattail fescue field including more &lt;em&gt;Pheropsophus jessoensis&lt;/em&gt; while the white clover had an elevated number of wolf spiders, earwigs and &lt;em&gt;Amara sp. &lt;/em&gt;(a weed seed predator). This discovery indicates that the type of undergrowth vegetation plays an important role in enhancing functional biodiversity. The kind of pests and weeds that these arthropods are effective against, as well as the extent to which their densities can be decreased, is also unknown. Therefore, further research on the feeding habit and predation of these arthropods should be conducted.&lt;/p&gt;

不同林分密度杉木林生态系统碳密度及其垂直空间分配特征

以不同林分密度(1800、3000、4500株/hm²)杉木林为研究对象, 通过野外调查、样品采集和室内分析, 研究不同林分密度杉木林生态系统碳密度及其分配特征。结果表明：1)三种林分密度杉木林生态系统碳密度分别为131.54、161.42、172.69 t/hm², 随林分密度增大而升高, 且具有显著差异(P < 0.05)。杉木林碳密度表现为土壤层>乔木层>林下地被物层。土壤有机碳储量占总碳储量的比例最大(53.11%-67.37%), 其次是树干、树根、树皮(25.89%-35.74%), 高密度杉木林分有利于树干、树皮、树根碳密度分配比例的增加。2)乔木层, 树干、树皮、宿留枯枝及宿留枯叶碳密度随林分密度增大而升高, 鲜枝及鲜叶碳密度随林分密度增大先升高后降低, 且均具显著差异(P < 0.05)；树干、树皮碳密度随树体高度的升高而降低, 鲜枝鲜叶碳密度集中于树体中上部(8 m≤h≤10 m), 宿留枯枝枯叶碳密度集中分布于树体中部(4 m≤h≤8 m)。3)随着林分密度的增大, 不同径级根碳密度呈上升趋势, 且不同径级根碳密度随林分密度变化差异达显著水平(P < 0.05)；不同径级间碳密度：根头>粗根>大根>中根>小根>细根, 根头和粗根占比最大(57.38%-70.84%)。4)林下植被碳密度随林分密度增大不断降低, 而林下凋落物碳密度随林分密度增大呈逐渐上升趋势, 且具显著差异(P < 0.05)。5)土壤层碳密度随土壤深度增加逐渐降低, 不同林分密度土壤层碳密度没有显著差异(P>0.05)。综上所述, 适当增加林分密度有利于提高杉木林生态系统的碳密度。;Cunninghamia lanceolata plantation with densities of 1800, 3000 and 4500 plants/hm² were employed to investigate the carbon density and its distribution characteristics of C. lanceolata forest ecosystem under different stand densities through field investigation, sample collection and analysis. The results showed that: 1) the carbon density in the C.lanceolata ecosystem with stand densities of 1800, 3000 and 4500 plants/hm² were 131.54 t/hm², 161.42 t /hm² and 172.69 t/hm², respectively, and increased significantly with the increase of stand densities (P < 0.05). The carbon density of C. lanceolata forest followed the order of soil layer > tree layer > understory layer. Soil organic carbon storage accounted for the largest proportion of total carbon storage (53.11%-67.37%), followed by trunk, root and bark (25.89%-35.74%). High stand density could increase the carbon density distribution portion in trunk, bark and root. 2) The carbon density of tree layer, trunk, bark and persistent withered branches and leaves increased with the increase of stand densities, while the carbon density of fresh branches and leaves displayed first increase and then decrease tendency with the increasing stand densities, which all showed significantly decreased with the increase of stand densities (P < 0.05). The carbon density of trunk and bark decreased with the increase of tree height. The carbon density of fresh branches and leaves were relatively high in the middle and upper part of tree (8 m≤h≤10 m), while for withered branches and leaves, higher carbon density was observed in the middle of the tree (4 m≤h≤8 m). 3) The carbon density in roots of different diameter increased significantly with the increase of stand densities (P < 0.05). The carbon density among different roots diameter was as follows: root head > coarse root > big root > middle root > small root > fine root, and root head and coarse root accounted for the largest portion (57.38%-70.84%). 4) The carbon density of undergrowth vegetation decreased with the increase of stand densities, while the opposite trend was observed for litter, which showed significantly decreased with the increase of stand densities (P < 0.05). 5) The carbon density of soil layer decreased with the increase of soil depth, and no significant difference was observed for different stand densities (P>0.05). 6) In summary, appropriate increase stand density is beneficial to improve the carbon density of C. lanceolata forest ecosystem.

Strip Clearcutting Drives Vegetation Diversity and Composition in the Moso Bamboo Forests

Abstract Strip clearcutting of Moso bamboo forests in southern China has seen increasing interest as a way of reducing harvesting costs. Previous research has shown that cutting influences the overstory structure and drives changes in the microclimate and soil properties. However, the effects of strip cutting on understory vegetation diversity and composition remain unclear. To better understand the influence of cutting on the understory vegetation, this study compares sites under natural restoration after cut and uncut sites in the Moso bamboo forest. We selected plots that were cut in 2019 (C19) and 2017 (C17), as well as unharvested plots as controls (CK). The results showed that strip clearcutting increased the understory vegetation richness and diversity, and a significant difference (A = 0.23, P = 0.001) existed in the composition of the vegetation between the three treatments. Furthermore, the decrease of soil total phosphorus and total potassium content resulted in the difference in undergrowth vegetation distribution and composition between the uncut plots and the cut plots. Our results suggest that strip clearcutting may not be harmful to biodiversity on a local scale in the Moso bamboo forest.

First Report of Colletotrichum brevisporum Causing Anthracnose of Dalbergia odorifera in China.

Dalbergia odorifera T. Chen (family Fabaceae) is one of four prized species of mahogany plant in China. In June 2017, an investigation of the condition of anthracnose was carried out on apporximately 333 hectares of D. odorifera plantations in Haikou City, Hainan Province (110.19°E, 20.03°N). Approximately 40% of D. odorifera plants had disease symptoms. Lesions on leaves were brown to grayish-white containing black dots and dark-brown borders, occasionally surrounded by a yellowish-green halo. Leaf spots generally occurred along the edge of the leaf. Severely infected leaves became withered and died. Hyphal growth was recovered from symptomatic leaf tissue, surface-sterilized with a 75% ethanol solution for 30s, rinsed with sterile distilled water, plated on potato dextrose agar (PDA), and incubated at 26°C in the dark. The representative isolate JXHTC19 was recovered by transferring a hyphal tip to a fresh PDA plate to obtain a pure culture. Fungal colonies had white aerial mycelium initially, turning pale gray after 3 days. At 7 days, colonies had a cottony appearance ranging from white to dark gray with orange masses of conidia. The colony surface was slimy and aerial mycelium was sparse. Isolates displayed single-celled, cylindrical, hyaline conidia that were rounded at both ends, and were 9.7 - 16.4 μm long (avg. 13.5 μm) × 3.6 - 6.2 μm wide (vg. 4.8 μm) (n = 100). To further identify the fungus, genomic DNA was extracted from single conidial cultures of JXHTC19. The rDNA internal transcribed spacer (ITS) region, glutamine synthetase (GS) gene, partial sequence of glyceraldeyde-3-phosphate dehydrogenase-like (GAPDH) gene, actin (ACT) gene, and beta-tubulin (TUB2) gene were amplified using the primer pairs ITS4/ITS5, GS-F/GS-R, GDF1/GDR1, ACT-512F/ACT-783R, and TUB2-T1/Bt-2b (Weir et al 2012), respectively. The results showed that the ITS, GS, GAPDH, ACT and TUB2 genes of the target strain (JXHTC19) have 100%, 95%, 100%, 97% and 98% sequence homology with C. brevisporum, respectively. The sequences obtained were deposited in GenBank (MF993572, MN737615, MN737614, MG515612, and MG515615[LJ1]). All five sequences were analyzed together with representative sequences from type or ex-type specimens of the Colletotrichum genus (Yang et al. 2011, Weir et al. 2012) and a phylogenetic tree was generated via the neighbor-joining method using MEGA6. The tree placed the isolate in the same group as C. brevisporum. Thus, both morphological and molecular characteristics identified the pathogen as C. brevisporum. To verify Koch's postulates, two-year-old leaves of healthy potted D. odorifera plants (n = 6) were inoculated with a spore suspensions of JXHTC19 that contained 105 conidia/ml. Plants were sprayed with water to serve as mock-inoculated controls [LJ2](Garibaldi et al, 2020). Six plants per treatment were used in each test. The test was repeated once.Plants were incubated in moist chambers at 26°C and monitored daily for symptom development. After five days, eleven of twelve isolates [LJ3]caused lesions on all inoculated plants, whereas no symptoms developed on the mock-inoculated controls. Koch's postulates were fulfilled by reisolating the same fungus and verifying its colony and morphological characters as C. brevisporum. To our knowledge, this is the first report of this species causing anthracnose of D. odorifera in China. Corresponding measures must be adopted to manage this disease such as reducing the planting density of D. odorifera and increasing the species diversity of undergrowth vegetation. These results could help develop better monitoring and management practices for this disease.

Effects of exotic plantation expansion and management intervention on woody plant species diversity, regeneration and soil seed bank in Tarmaber district, Ethiopia

This study was carried out to determine the effect of plantation forest with management intervention on woody plant species diversity in Tarmaber district north shewa zone Ethiopia, regeneration and soil seed bank species composition in five different forest types. A total of 75 circular sample plots of 314 m2 were established along a transect lines. Soil seed bank analysis was done from soil samples collected in each of the plots (225 samples). Different diversity index and ANOVA was used in SPSS software for analysis. The result showed that a total of 51 woody plant species was recorded in adjacent natural forest (41), managed C. lusitanica (27), not managed C. lusitanica (9), managed E. globules (22) and not managed E. globules (13) species. Regeneration of seedlings were 3538, 5567, 707, 1462 and 2524 mean stems ha-1 for natural forest, managed C. lusitanica, not managed C. lusitanica, managed E. globules and not managed E. globules respectively. Unmanaged C. lusitanica plantations had significantly lower densities of mature tree stems ha-1 as compared to managed C. lusitanica, managed E. globules and adjacent natural forest (F=14.03, p&lt;0.05). Similarly in terms of sapling density ha-1 unmanaged C. lusitanica was significantly lower from other forest types (F=7.37, p &lt;0.05). However managed C. lusitanica had significantly higher seedling regeneration (stem density ha-1) than other plantation and adjacent natural forests (F = 16.11, p &lt; 0.05). Generally mean stem densities including tree, sapling and seedling of woody species among different forest types managed C. lusitanica was significantly higher among different forest types (F= 13.01, p&lt;0.05). From the soil seed bank a total of 22 plant species (20 native and 2 exotic) species were recovered. In different forest types the number of species recorded was in adjacent natural forest (19), managed C. lusitanica (11), unmanaged C. lusitanica (4), managed E. globules (7) and unmanaged E. globules (5). Generally, with appropriate management intervention, undergrowth vegetation and soil seed bank status in plantation forest had good species composition and diversity.