Tree Layer Research Articles

Altitudinal Variation in Species Diversity, Distribution, and Regeneration Status of a Secondary Picea Forest in Guandi Mountain, Northern China

Altitude plays a crucial role in shaping the diversity and distribution of species in forest landscapes in mountainous regions. However, existing studies often lack comprehensive analysis of the intricate relationships among environmental factors, disturbances, and species diversity. This study aims to address this gap by thoroughly analyzing major species’ diversity, distribution, and regeneration status, along with their influencing factors, across different altitudinal gradients (1850 to 2350 m). Field surveys were conducted to examine the major species in different vegetation layers of the secondary Picea forest in Guandi Mountain. The key findings from the study include the following: (1) the study area recorded a total of nine species of adult trees, belonging to eight genera in five families, fourteen species of shrubs from eight genera in five families, and fifty-two herb species representing forty-eight genera in twenty-six families. Dominant species varied across layers, with Picea asperata Mast. and Larix principis-rupprechtii Mayr. dominating the arborous layer, Lonicera ferdinandii Franch. and Cotoneaster acutifolius Turcz. in the shrub layer, and Poa pratensis L. and Duchesnea indica (Andrews.) Focke in the herb layer. (2) Altitude significantly influenced species diversity, with the most pronounced effects observed in the shrub and herb layers. (3) Tree species regeneration varied with altitude, with Picea asperata exhibiting the highest regeneration performance, particularly in the high-altitude zone (2250–2350 m). Regeneration parameters were significantly correlated with species diversity indices in both tree and shrub layers. (4) Redundancy analysis revealed that, apart from altitude, cutting (p = 0.015) influenced the species diversity of the tree layer, while annual precipitation (p = 0.006) and temperature (p = 0.01) determined the diversity of the shrub layer. Grazing (p = 0.042) was identified as a determining factor for species diversity in the herb layer. Overall, these findings provide valuable insights into the sustainable management of forest ecosystems in the study area and offer practical guidance for forest management in similar mountainous landscapes worldwide.

Too Warm and Too Dry—Decline and Threat of the Subarctic-Subalpine Liverwort Hygrobiella laxifolia in a Low Mountain Range in Central Europe under the Conditions of Climate Change

Using the liverwort Hygrobiella laxiflora as an example, this study aims to investigate the impact of climate change on montane species and their ecosystems. The study area is the Elbe Sandstone Mountains in Germany and the Czech Republic, where Hygrobiella laxifolia has an isolated occurrence in deeply carved gorges characterized by a specific microclimate (cellar climate). The focus is on determining the rate at which populations are affected. After little change in the population over a long period, a sudden sharp decline has been observed in recent years. The decline correlates with the mass proliferation of the European spruce bark beetle (Ips typographus) observed since 2017, which has led to a strong thinning of the forests in the area. In many areas of occurrence, the forests now have a much sparser tree layer or none at all. Competition from other, more competitive species also plays an important role as a cause of decline, as these have spread more widely on the sites due to the now higher light levels. The severe bark beetle infestation and the large-scale forest fire of 2022 both represent events that led to the almost complete deforestation of large parts of the study area, which was previously unknown on this scale. Since both the bark beetle infestation and the forest fire are strongly intensified by climate change, we assume that climate change is the main reason for the decline of Hygrobiella laxifolia in the area. The populations of Hygrobiella laxifolia of the Elbe Sandstone Mountains show some morphological peculiarities. As two new species have recently been described within Hygrobiella, we have integrated a sample from the area into a molecular phylogeny of Hygrobiella based on the plastid sequences of trnL-trnF intergenic spacer and matK to clarify the relationships. The sample from Elbe Sandstone Mountains fits well into the clade of Hygrobiella laxifolia.

Habitat Degradation Facilitates the Invasion of Neophytes: A Resurvey Study Based on Permanent Vegetation Plots in Oak Forests in Slovenia (Europe).

The spread of neophytes (non-native plant species) challenges the conservation status and ecological integrity of forests, especially in lowland areas. Long-term resurvey studies are needed to evaluate the temporal dynamics of neophytes in forests; however, such data are scarce. In 2023, we resampled a set of 45 permanent vegetation plots (established in 1992/93) in two forest vegetation types: oak-hornbeam forests dominated by Quercus robur and colline oak-beech forests dominated by Q. petraea. Over the last 30 years, oak forests have experienced extensive oak tree mortality, with the degree of habitat degradation being greater in Q. robur forests. In the early 1990s, only three neophytes with low abundance were recorded across all plots. In the 2023 resurvey, the total number of neophytes increased to 22 species (15 herbaceous and 7 woody species), comprising 6.9% of the total species pool in the understory layer. The increase in the plot-level number and cover of neophytes was significant in plots dominated by Q. robur but not in those with Q. petraea. The most frequent neophytes were Impatiens parviflora (present in 31% of plots), Solidago gigantea (27%), Erigeron annuus (16%) and Erechtites hieraciifolia (16%). The richness and cover of neophytes were significantly affected by the tree layer cover (negative correlation) and the degree of soil disturbance (positive correlation). All neophytes established in disturbed patches, whereas the occurrence of I. parviflora was exceptional as it was able to colonize less degraded, shaded understory environments. Habitat degradation (the mortality-induced loss of stand-forming oak trees resulting in extensive tree layer cover decrease) emerged as a key driver promoting neophyte proliferation, coupled with the impact of management-induced disturbances affecting overstory and soil conditions. The spread is expected to continue or even intensify in the future because novel light regimes and disturbances make forest habitats less resistant to neophyte proliferation.

Organization of forest geosystems in the Lower Amur region by a case study of the Komsomol’sky Nature Reserve

This article is devoted to the structural-functional organization of the forest geosystems of Komsomol’sky Nature Reserve located in the south of the Lower Amur Region. It considers a landscape organization model built using the information theory methods. The model is represented as a block diagram consisting of digraphs, in whose center there are landscape features. This model is a modified version of the previously published one for the studied territory. It is built on the basis of richer field data and with the addition of previously unused landscape features. Weak links of medium density predominate in the model, which may indicate the stability of the forest geosystems formed there. Our analysis shows that the main factors determining the structure of Komsomol’sky Nature Reserve’s forest geosystems are altitudinal-exposure zonality, altitude, lithology of parent rocks, and soil hydrothermal conditions. It is established that the stand of timber is directly related to the humus soil horizon lithomass: it decreases with an increase in lithomass. Plants biomass is highly dependent on the steepness of slopes: it decreases with its increase. Separate relationships have been revealed for plant layers. The herbaceous layer height decreases with an increase in the altitude and lithom ass in the soil. The herbage floristic diversity differs greatly in land facie groups and has a maximum in the ridge-top areas of the slopes and at the foot hill. The shrub layer height depends on soil moisture content, lithology of parent rocks and lithomass: it de-creases with increasing soil moisture content most of all and increases with increasing lithomass in the soil. A relationship has been found only with the lithomass in the soil for all tree layer features. A lithomass increase has a depressing effect on trees.

What makes agroforestry work?

This review summarizes findings from 22 case studies published together in Tropical Forest Issues 61 (Torquebiau 2024). The case studies present clear and tangible benefits from the adoption of agroforestry, based on a wide range of practices from Africa, Latin America and Asia. In this review practices and conditions for tangible benefits of agroforestry are summarized. The practices are presented in four categories: crops under trees or intercropped with trees; annual crops under multispecies tree cover; perennial crops under multispecies tree layers; and agroforests. The conditions cover seven thematic areas: social and human capital; attention to women; governance priorities; technical assistance and capacity strengthening; legal, institutional and policy frameworks; economic research; and value chains.

Elevation gradients alter vegetation attributes in mountain ecosystems of eastern Himalaya, India

The present study describes how vegetation (the tree layer) is shaped along the elevation gradients in the eastern part of the Indian Himalayan Region. Various vegetation attributes, distribution, population structure, and regeneration patterns of 75 tree species belonging to 31 families were studied. Tree species richness shows a low plateau (peaked between 1,300–1,500 m) with a linearly decreasing pattern above 1,500 m asl. Ericaceae was found as the dominant family, followed by Lauraceae and Rosaceae. The distributional pattern of species-to-genera ratio (S/G) did not follow any particular trends, while β-diversity increased along the elevation gradient. The Margalef index of species richness, the Menheink index of species richness, and the Fisher alpha were found to be highest at lower altitudes (1,000–1,500 m), while the Simpson index was highest at middle altitudes (2,600–3,000 m). Random distribution was shown by maximum tree species (47.3%), followed by a contagious distribution (42.9%), and regular distribution (10.8%). The regeneration of tree species was found to be good with a healthier number of seedlings (10.2%), fair (43.5%), poor (30.3%), while 16% were observed not regenerating. Acer laevigatum (1,500 m), Prunus nepalensis (3,300 m), Viburnum sympodiale (3,400 m) were among the new regenerating species at the respective altitudes. The population structure of tree species in terms of proportion of individuals in seedlings, saplings, and the adult class varied in all the elevation transects. Species with better regeneration on upper distribution limits have been recognized as probable for upward movement.

How to classify forests? A case study from Central Europe

Aims: Inconsistent treatment of the vegetation layers is one of the main problems in the floristic classification of forests. In this study I investigate whether a classification based solely on woody species leads to units similar to the Braun-Blanquet system or to something completely different. Study area: Austria (Central Europe) and adjacent regions. Methods: 23,681 forest relevés from the Austrian Vegetation Database were classified using TWINSPAN. Spruce and pine plantations and stands with a cover of non-native woody species > 5% were excluded from the dataset. Only native tree and shrub species were used in the classification while herbs, dwarf shrubs, cryptogams and all records of woody species in the herb layer were omitted. Results: The TWINSPAN classification revealed elevation (i.e., climate) as the main floristic gradient in the data set. Within lowland communities, soil moisture was the dominant factor. The higher units of the Braun-Blanquet system were mostly well reproduced. Conclusions: The higher levels of the phytosociological forest classification (class, order, partly also alliance) can basically be defined by taking only the shrub and tree layer into account. However, all past and current classifications suffer from arbitrary exceptions to this rule. This leads to many inconsistencies and blurs the main biogeographical patterns within European forests. Here I argue that using the tree and shrub species for defining the higher levels and the understorey species for defining the lower ones is best suited to meet the properties that users would expect from a good forest classification. Taxonomic reference: Fischer et al. (2008). Syntaxonomic reference: Mucina et al. (2016) if not stated otherwise. Abbreviations: EVC = EuroVegChecklist (Mucina et al. 2016).

The chemical stoichiometry characteristics of plant-soil carbon and nitrogen in subtropical Pinus massoniana natural forests

Ecological stoichiometry is essential for understanding changes in ecosystem structure and nutrient cycling in forest ecosystems. However, the stoichiometric characteristics of carbon (C) and nitrogen (N) in different organs or layers, such as leaves, branches, trunks, roots, understory vegetation, litter, and soil within a forest ecosystem, have remained poorly understood. In this study, four age groups of Pinus massoniana natural forest including young, middle-aged, near-mature, and mature were selected as research subjects to illustrate the C and N stoichiometry interactions among different layers and organs in the forest ecosystem. The results showed that the average C and N concentrations in the leaves of the tree layer, shrub layer, and herb aboveground parts (HAP) were higher than that of other tree and shrub organs, as well as the herb underground parts (HUP), respectively. The N concentrations of tree branches and trunks showed a trend of increase first and decrease later from young to mature phases, but the C:N ratios presented an opposite trend. The C concentrations.in all tissues in shrubs showed a first decline and then a rise with age. As age progressed, the N concentration in each ecosystem layer increased gradually and demonstrated high synergy. The mineralization of organic matter in the soil was generally slow. The C concentrations in the understory vegetation layer were significantly positively correlated with the C concentrations in the litter layer but negatively correlated with the soil layer, and the C concentrations in the litter layer were also significantly negatively correlated with the C concentrations in the soil layer. The research findings can provide a reference basis for the formulation of nutrient regulation and sustainable management measures in the natural forests of P. massoniana in the study area.

Differential Analysis of Island Mountain Plant Community Characteristics: Ecological Sensitivity Perspectives

Island plants form the foundation for maintaining the ecology of an island. With the development of the island’s infrastructure, its ecosystems become damaged to a certain extent. A comprehensive understanding of island habitats and plant community characteristics is crucial for the development of island plant communities. This paper focuses on Pingtan Island in Fujian Province, China, as the research subject. Firstly, considering the significance of the wind environment on the island, this study constructed a wind environment model for the entire island of Pingtan to evaluate the ecological sensitivity from a macro perspective. Subsequently, 33 typical sample plots were selected based on different ecologically sensitive areas to conduct a micro-survey and the characterization of the montane plant communities on Pingtan Island. The findings reveal that (1) Pingtan Island’s ecological sensitivity is dominated by areas with ecological insensitivity (35.72%), moderate ecological sensitivity (33.99%), and high ecological sensitivity (18.02%). The soil texture, wind environment, and land use type are the primary influencing factors in the ecological sensitivity of Pingtan Island. (2) A total of 47 families, 82 genera, and 93 species of plants were investigated in a typical sample site in the mountainous area of Pingtan Island. The plant community structure was dominated by the successional stage of shrubs and herbs. There is some similarity in the plant composition of different ecologically sensitive areas. High ecologically sensitive areas have more species. As sensitivity increases, the dominant species in the three ecologically sensitive areas continue to undergo plant succession from Acacia confusa to Pinus thunbergii to Eurya emarginata. (3) Both community characteristics and species diversity vary between sensitive areas. The canopy density (CD) and the mean height of tree layer (MHTL) are higher in moderate ecologically sensitive areas. The mean tree diameter at breast height (MDBH) and the mean height of shrub layer (MHSL) are higher in high ecologically sensitive areas, while the mean height of herb layer (MHHL) is higher in extreme ecologically sensitive areas. Four diversity indicators increase with increasing sensitivity. In the moderate and high ecologically sensitive areas, Casuarina equisetifolia and A. confusa thrive, with Pinus thunbergii showing the opposite trend. However, species diversity is better characterized by A. confusa and P. thunbergii, with C. equisetifolia being the least diverse. Both the community characteristics and species diversity of P. thunbergii are optimal in extreme ecologically sensitive areas. In this study, the ecological sensitivity of Pingtan Island and the characteristics of montane plant communities were systematically analyzed to explore more stable montane plant communities on the island, aiming to provide a scientific basis and model reference for the ecological restoration and sustainable development of Pingtan Island and other islands.

Fusion of airborne multimodal point clouds for vegetation parameter correction extraction in burned areas.

Most experimental studies use unimodal data for processing, the RGB image point cloud cannot separate the shrub and tree layers according to the visible vegetation index, and the airborne laser point cloud is difficult to distinguish between the ground and grass ranges, to address the above problems, a multi-band information image fusing the LiDAR point cloud and the RGB image point cloud is constructed. In this study, data collected from UAV platforms, including RGB image point clouds and laser point clouds, were used to construct a fine canopy height model (using laser point cloud data) and high-definition digital orthophotos (using image point cloud data), and the orthophotos were fused with a canopy height model (CHM) by selecting the Difference Enhancement Vegetation Index (DEVI) and Normalised Green-Blue Discrepancy Index (NGBDI) after comparing the accuracy of different indices. Morphological reconstruction of CHM + DEVI/NGBDI fusion image, remove unreasonable values; construct training samples, using classification regression tree algorithm, segmentation of the range of the burned areas and adaptive extraction of vegetation as trees, shrubs and grasslands, tree areas as foreground markers using the local maximum algorithm to detect the tree apexes, the non-tree areas are assigned to be the background markers, and the Watershed Transform is performed to obtain the segmentation contour; the original laser point cloud is divided into chunks according to the segmented single-tree contour, and the highest point is traversed to search for the highest point, and corrected for the height of the single-tree elevations one by one. Accuracy analysis of the vegetation information extracted by the method with the measured data showed that the improved method increased the overall recall rate by 4.1%, the overall precision rate by 3.7%, the overall accuracy F1 score by 3.9%, and the tree height accuracy by 8.8%, 1.4%, 1.7%, 6.4%, 1.8%, and 0.3%, respectively, in the six sampling plots. The effectiveness of the improved method is verified, while the higher the degree of vegetation mixing in the region the better the extraction effect of the improved algorithm.

Recent tree diversity increase in NE Iberian forests following intense management release: A task for animal‐dispersed and drought‐tolerant species

Abstract Under increasing human‐related threats to forests, many studies suggest that increasing tree species diversity may boost forest resilience by enhancing the range of species' responses to disturbances. However, it remains unclear whether passive or active forest management strategies should be applied to increase tree diversity. This issue would benefit from investigating which management and environmental factors, together with species' functional traits, influence temporal changes in tree species diversity. We explored the influence of the bioclimatic region, land‐use history, forest cover, protection, management, forest structure and changes in temperature and precipitation, to explain tree species diversity changes in NE Iberian forests, by comparing 3141 plots from the Spanish National Forest Inventory sampled between 1989 and 2016. Moreover, we assessed which species' functional traits (dispersal habit, drought and shade tolerance) were most relevant for diversity changes. After 27 years, tree species richness and diversity moderately increased in the tree and regeneration layers. This trend occurred mostly in long‐established, non‐recently managed forests and in those with a lower initial basal area. Increasing temperature had negative effects for diversity increase in the tree layer but positive for the regeneration compartment, while decreasing precipitation showed the opposite effects. Tree species with higher drought tolerance, and especially those animal‐dispersed ones arriving from the regional pool, mostly contributed to the local diversity increase. This pattern occurred in all forest types, although the taxonomic array of species varied. Synthesis and applications. The main drivers influencing the passive increase in tree species diversity suggest a primary role of diminishing forest exploitation in this recovery process, fine‐tuned by climatic changes. This ecological scenario has particularly favoured animal‐dispersed tree species with higher drought tolerance, which mostly led the diversity increase. A higher presence of such highly mobile and drought‐tolerant species can be crucial to increase functional diversity and, ultimately, increase forest resilience under future scenarios of greater aridity. In light of these results, management strategies should continue fostering the restoration of diversity in once intensively exploited forests while ensuring the maintenance of the already gained tree species diversity.

Co-Creating Strategies to Optimize Traditional Silvopastoral Systems through the Management of Native Trees in Caívas in Southern Brazil

The conservation of forest remnants in southern Brazil is closely related to historical land use, for example in systems such as caívas that occur within remnants of the Araucaria Forest and include livestock production and the extraction of yerba mate. Over the last decade, technologies adapted for these systems have been developed that promote a significant increase in animal productivity, without harming forest regeneration or the maintenance of the tree layer. However, the fertilization of pastures proposed in the technology has also promoted greater growth of native trees, with a consequent increase in shade levels. This, in turn, has affected the maintenance of pasture and yerba mate in the understory. Thus, this study sought to develop a methodology to adjust shade levels based on forest management that adheres to the limits permitted by current legislation. The objective was to evaluate the effect of tree management to maintain 50% shade levels on environmental indicators in a caíva that has been implementing pasture improvement technology since 2013. Native tree management occurred in 2020 and 2022 and the results were compared with data from the floristic survey of the area carried out in 2013. The results indicate that although the adoption of forest management to adjust shade levels reduced the density of individuals, it did not affect forest diversity, nor the basal area of the caíva tree layer. As such, it is possible to maintain pasture and yerba mate production in the area. Strategies like this are fundamental so that the forest landscape can continue to offer a source of production while also supporting environmental conservation.

Horizontal pattern of trees in the cenopopulation of <i>Larix gmelinii</i> (Rupr.) Rupr. in the forest tundra ecotone on the Taimyr Peninsula

The features of the horizontal spatial structure of multi-aged open forests of Gmelin larch (Larix gmelinii (Rupr.) Rupr.), forming the northern limit of tree vegetation in the forest-tundra ecotone in the eastern part of the Taimyr Peninsula, are considered. It was found that all studied tree stands are characterized by a mosaic structure, in which areas occupied by woody vegetation alternate with open spaces, the area of which ranges from 37 to 50%. In all cases, the composition of the tree layer includes both single trees and their aggregations (biogroups), share of which varies from 17 to 32%. Pair aggregation of trees predominates in biogroups, amounting to 83%. The predominance of the random nature of the location of trees in the formation of the horizontal pattern has been snown, but the specific type of spatial distribution is also determined by the stage of ontogenesis in which the cenopopulation is located.

Effects of community structure of Cunninghamia lanceolata sprouting forests with different densities on ecosystem carbon density at the early stage of succession.

To explore potential responses of ecosystem carbon density to changes of community structure during natural regeneration of woody plants, we analyzed the relationships between ecosystem carbon density and its components, tree species diversity, structural diversity (CVDBH) and spatial structure parameters (mingling, aggregation, dominance, crowding) of Cunninghamia lanceolata forests with different sprouting densities (1154, 847 and 465 individuals·hm-2) at the early stage of succession in Baishanzu National Park. The results showed that tree species diversity (species richness index and Shannon diversity index) increased with the decrease of sprouting density of C. lanceolata. Among the stand structural parameters, CVDBH, stand density, and mingling increased with the decrease of sprouting density of C. lanceolata. The stand distribution pattern of different C. lanceolata densities was uniform, with sub-dominant stand growth status and relatively dense status. The carbon density of tree layer under high, medium, and low sprouting densities of C. lanceolata were 57.56, 56.12 and 46.54 t·hm-2, soil carbon density were 104.35, 122.71 and 142.00 t·hm-2, and the total carbon density of ecosystem were 164.59, 182.41 and 190.13 t·hm-2, respectively. There was little variation in carbon density of understory layer and litter layer among different treatments. The carbon density distribution characteristics of different C. lanceolata densities were following the order of soil layer (63.4%-74.7%) > tree layer (24.5%-35.0%) > understory layer and litter layer (0.8%-2.0%). The results of variance partitioning analysis indicated that the change of tree layer carbon density was mainly influenced by stand structure diversity, soil layer carbon density was influenced by both tree species diversity and stand structure diversity, while ecosystem carbon density was mainly influenced by tree species diversity. Stand spatial structure parameters had a relatively little effect on ecosystem carbon density and its components. The sprouting density of C. lanceolata significantly affected ecosystem carbon accumulation during the conversion from C. lanceolata plantations to natural forests. A lower remaining density of C. lanceolata (about 500 individuals·hm-2) was more conducive to forest carbon sequestration.

Multi-ecosystem services differently affected by over-canopy and understory nitrogen additions in a typical subtropical forest.

Obtaining a holistic understanding of the impacts of atmospheric nitrogen deposition on multiple ecosystem services of forest is essential for developing comprehensive and sustainable strategies, particularly in heavy N deposition regions such as subtropical China. However, such impacts remain incompletely understood, with most previous studies focus on individual ecosystem function or service via understory N addition experiments. To address this knowledge gap, we quantified the effects of over-canopy and understory N additions on multiple ecosystem services based on a 7-year large-scale field experiment in a typical subtropical forest. Our results showed continued over-canopy N addition with 50 kg ha-1 year-1 over a period of 4-7 years significantly increased plant nutrient retention, but did not affect the services of soil nutrient accumulation, water yield, C sequestration (in plants and soil), or oxygen release. There were trade-offs between the soil and plant on providing the services of nutrient accumulation/retention and C sequestration under over-canopy N addition. However, without uptake and retention of tree canopy, the trade-off between soil and plant were more weaken under the understory N addition with 50 kg ha-1 year-1 , and their relationships were even synergetic under the understory N addition with 25 kg ha-1 year-1 . The results suggest that understory N addition cannot accurately simulate the effects of atmospheric N deposition on multiple services, along with mutual relationships. Interestingly, the services of plant N, P retention, and C sequestration exhibited a synergetic increase under the over-canopy N addition but a decrease under the understory N addition. Our results also found tree layer plays a primary role in providing plant nutrient retention service and is sensitive to atmospheric N deposition. Further studies are needed to investigate the generalized effects of forest canopy processes on alleviating the threaten of global change factors in different forest ecosystems.

Structure and Composition of Woody Species in the Kpatawee Tropical Rainforest in Liberia

Studying ecosystem structure and species composition is pivotal, offering critical insights into environmental health and biodiversity. It facilitates the evaluation of environmental changes, like deforestation and climate shifts, and their influence on species dynamics within ecosystems. Our study aimed to assess the woody species composition and structure within Liberia's Kpatawee tropical rainforest. We conducted transect walks, crossing the forest south-north and east-west, establishing six 20 m x 20 m sampling plots. Using the PlantNet plant species identifier tool, we cataloged surviving trees with a DBH ≥ 5 cm, including their scientific names. Results unveiled 71 tree species across 42 families, with Leguminosae displaying the highest diversity. Prominent species included Quararibea asterolepis, Hasseltia floribunda, and Castilla elastica. An intriguing inverted J-shaped pattern in diameter distribution linked to stem-stand shrubs, small-sized trees, and young large trees characterized the first class. The tree layer, mainly species like Garcinia benthamiana, Iramyan therasagotiana, and Eschweilera decolarans, contributed significantly to the total DBH (65.45%). Total basal area (BA) for trees DBH ≥ 5 cm was 16.39 m² ha-1. Notably, eight species accounted for 93% of the basal area, reflecting a concentration of individuals in lower DBH classes in the first category. This trend suggests a gradual decline in numbers in higher DBH classes. Consequently, we recommend implementing sustainable forest management to mitigate the impacts of selective cutting on forest recruitment and regeneration processes. The inverted J-shaped pattern, indicating prolific regeneration but limited recruitment, possibly due to selective cutting, underscores the imperative for prudent forest management.

Impacts of forest fire frequency on structure and composition of tropical moist deciduous forest communities of Bandhavgarh Tiger Reserve, Central India

Forest fire is one of the prominent factors especially in tropical seasonal forests that have a variety of consequences on ecosystem composition, structure and function depending upon the type of fire, fire intensity, and fire frequency. Forest fire incidences have been increasing in the last few decades especially in tropical moist forests, raising the concerns for forest restoration and management since the inhabiting plants in these forest communities largely lack adaptive strategies. The present study was carried out in tropical moist deciduous forests to (A) understand the patterns of forest fire frequency by delineating the fire affected areas and (B) evaluate the impacts of forest fire frequency on species composition, diversity and regeneration of a moist deciduous forest of Central India. A fire frequency map was prepared using Landsat satellite images from 2005 to 2021 for the study purpose. Vegetation data were collected from field surveys for each fire frequency class separately. Results of the present study showed that 25.12 % area was affected by low frequent fires, 2.92 % by moderate frequent fires and 0.099 % by high frequent fires, whereas 71.85 % area remained unaffected by fire. The diversity of the tree layer was highest in the low fire frequency class whereas, for the sapling layer, it was highest in unburned areas. Overall, the negative impact of fire frequency on species diversity was observed for the tree and sapling layers. Favorable effects of fire on young current year recruitments were observed as a result of the removal of seed dormancy. Results indicate that moderate fire frequency in moist deciduous forests helps to increase tree density. Contrary to this, unburned areas are suitable for species diversity of seedlings and saplings which consequently decides the composition of mature vegetation. Overall, a negative impact of fire frequency on density was observed for the sapling and seedling layers. Our study concludes that higher fire frequency is detrimental to both the density and diversity of tree, sapling and seedling layers, particularly in tropical moist deciduous forest communities of Central India. It is expected that fire incidences are likely to increase with the increasing temperatures as a result of climate change. In this context, the present study would be highly valuable for forest policy development as information on the impact of fire in tropical moist forests is lacking especially from Central Indian region.

Vegetation composition, tree diversity, Biomass and carbon stock of Kanger Valley National Park

This study focuses on vegetation composition, tree diversity, biomass and carbon stock within Kanger Valley National Park of Bastar district (C.G), a biodiverse hot spot located in central India. The research comprised of systematic field surveys to identify and document tree species present in various zones of the park. A combination of quantitative measures such as Phytosociological analysis, diversity indices, biomass and carbon stock were estimated. Density and basal cover of tree layer across the three study sites were 220 to 520 trees ha-1 and 18.56 to 26 m2 ha-1, respectively. Sapling layer density and basal cover across the three study sites were 110-260 trees ha-1 and 0.34-0.74 m2 ha-1, respectively. Shannon-Wiener diversity index respectively ranges from 2.88 to 3.39 for tree layer and 2.29 to 3.96 for saplings layer. Equitability were from 1.10-1.25 and 1.29 -1.59, respectively for tree and sapling layer, whereas, species richness was from 3.08- 5.53 for tree layer and 3.64 to 13.58 for sapling layer. Total biomass across the study sites was between 286.43 and 3144.44 t ha-1, and was maximum on site-1 and minimum on site III. Litter layer also followed the similar trend being maximum (3.85 t ha-1) on site I and minimum on site III (2.62 t ha-1). The total carbon stock ranged between 110.52t ha-1 and 133.87 t ha-1, being maximum on site I, and minimum on site III. The dominated tree species on site I was Anogesisssus latifoia and Caseria graveolens, site II was dominated by Shorea robusta and Pterocarpus marusupium ans site III was dominated by Schleichera oleosa and Semecarpus anacardium. Study revealed that the structure, diversity, biomass and carbon stock in present sudy site are the result of protection and conservation.

Plant community differentiation of desertification region in northwest Liaoning Province, China

Understanding plant communities in desertification area is the scientific basis of evaluating the local eco-environmental quality and carrying out desertification control. According to longitude, we divided the desertification area in northwest Liaoning Province into three regions: the eastern region (122°50'37″ -123°49'40″ E), the middle region (121°16'41″-122°35'00″ E), and the western region (119°20'03″ -120°02'41″ E), and investigated the plant communities in each region. The results showed that the proportion of forest and canopy density of tree layer increased from the west to the east. Ass. Pinus sylvestris var. mongolica and Ass. Populus sp. in the eastern, Ass. Pinus tabuliformis and Ass. Populus sp. in the middle, as well as Ass. P. tabuliformis and Ass. Prunus sibirica in the western were dominant communities, respectively. The proportion of brush community in the eastern, middle and western was 0, 22.2%, and 28.0%, respectively. Grasslands formed mainly by human disturbance in the eas-tern and middle regions. The total species numbers were 110 in the middle, 88 in the western and 75 in the eastern, respectively. Therophytes were dominant in the eastern and middle with proportions of 68.2% and 66.7%, respectively. Hemicryptophytes were the dominant type (36.3%) in the western region. The proportion of microphanerophyt, nanophanerophyte, chamaephyte, and geophyte increased from the eastern to the western. The species number, Shannon index, and Simpson diversity index of the middle were the highest among the three regions. Pielou evenness index increased gradually from the eastern to the western. Community similarity between the eastern and the western was the lowest, as shown by the β-biodiversity, and the similarity between the middle and the western was the highest. The community type, species number, characteristics of species composition and species biodiversity of the middle region had the characteristics of ecological transition zone. In general, vegetation status in the desertification area of northwest Liaoning Province was in good condition. There were still some problems including the monotonous vertical structure of forest and tree species as well as the serious human interference.

Stratification of vertical canopy structure to improve estimation of forest inventory attributes using airborne LiDAR data in a large subtropical region of China

Over the last two decades, airborne light detection and ranging (LiDAR) has been developed into an advanced tool for practical forest resource inventory monitoring over large areas. Nonetheless, improving the accuracy of forest inventory attribute estimations remains an ongoing challenge. This paper introduces a novel framework for estimating forest inventory attributes based on the stratification of vertical forest structures (VFS). According to the composition and spatial arrangement of the superior, middle, and inferior strata in the tree layer, the forest stand was classified into six distinct VFS classes. Subsequently, the multiplicative power models were established for the stratification-based estimations of the forest inventory attributes, including stand volume (VOL), basal area (BA), and above-ground biomass (AGB), by using a rule-based exhaustive combination approach, and their performances were comparatively analyzed. The result indicated that: compared to the accuracy (relative root mean squared error, rRMSE) of the species-based estimation, the weighted average rRMSE of stratumbased VOL, BA, and AGB estimations of four forest types (Chinese fir, Masson pine, eucalyptus, and broadleaf forests) decreased by 0.3%–7.3%, +3.6%–9.4%, and 0.7%–8.7%, respectively, and the accuracy was significantly improved after stratification. Even after clustering the VFS into two or three classes using cluster analysis, the accuracy of forest attribute estimations remained superior to that of the species-based estimations. Notably, the coefficients of variation for both forest attributes and LiDAR metrics experienced a substantial decrease, and their statistical relationship considerably strengthened within most strata post-VFS classification, which led to an improvement in the accuracy of the forest attribute estimations. The methodology presented in this paper provides a significant advance in improving the accuracy of forest inventory attributes for large areas using airborne LiDAR data.