Forest Composition Research Articles

Hindcasting and updating Landsat-based forest structure mapping across years to support forest management and planning

Forest vegetation mapping that integrates forest inventory data with multispectral remote sensing data provides valuable geospatial products for public land management agencies, but resource managers may require rapid updating of maps as new imagery becomes available (updating) or retrospective mapping for times prior to forest inventory plot measurement (hindcasting). While forest attribute mapping using Landsat multispectral imagery is common, the accuracy of applying models outside of reference epoch to support long-term forest monitoring is not normally quantified. We examine whether a Landsat-based mapping approach can support robust, temporally consistent multivariate mapping of forest structure and composition data in support of forest management planning and landscape analysis. Specifically, we ask: how accurate forest attribute mapping was when hindcasting or updating outside of a period of time when forest inventory plot data were available (reference epoch)? In the western Cascade Mountains of Oregon and California, USA, we used the gradient nearest neighbor approach to annually impute USDA Forest Inventory and Analysis (FIA) plot data (2001–2016) to all 30-m forested pixels based on temporally smoothed Landsat multispectral imagery (1986–2021), including basal area, canopy cover, quadratic mean diameter of dominant trees, stand height, and the density of large diameter trees. We made extrapolations from models fit to a 10-year reference epoch to both earlier periods (2001–2006 hindcast) and to later period (2011–2016 update) and quantified prediction accuracies relative to models based on the full data (2001–2016). To evaluate the influence of spatial scale on hindcasting and updating, we compared full and extrapolation model predictions at pixel-level (0.09 ha) and hexagon-level (780 ha).At the plot-level, we found no strong differences between the full and extrapolation model predictions for R2 and mean error nor among predicted vs. observed regression coefficients. At the pixel-level, average differences due to hindcasting and updating were near zero, though differences varied up to 20 % across pixels. At the hexagon-level, the range in map differences was small (+/- 5 %), but hindcasting resulted in lesser forest attribute predictions. We observed greater variability in pixel-level and hexagon-level prediction differences when hindcasting or updating was temporally further away from the reference period. Using 2001 hindcast and 2016 updated maps as a case study, we found that with hindcasting and updating map differences were spatially aggregated across the study region. Our results support Landsat-based hindcasting and updating of forest attribute mapping beyond the time period covered by forest plot data. Our results suggest aggregating data to coarse spatial resolutions may minimize differences due to hindcasting and updating. Further research is needed to identify the key drivers for prediction differences to improve the accuracy of both hindcasting and updating as a basis for forest monitoring.

Long-term ecological studies on the oxbow ecosystems development and fire history in the Drava river valley (Central Europe): Implications for ecological restoration

Oxbow lakes are important habitats for many rare and protected wetland organisms and play a role as a storage of pollutants in floodplain. Unfortunately, many oxbows were destroyed due to drainage works and the adaptation of riverbeds to inland transport. Multi-proxy palaeoecological analyses makes it possible to recognise the succession of flora and fauna in the oxbow lakes over centuries and millenia. Insight into the history of the destroyed wetlands ecosystems is especially important for their restoration. We used palaeoecological methods (plant macrofossils, pollen, mollusc, Cladocera, diatoms, macrocharcoal) supported by radiocarbon dating to: (i) reconstruct the succession of the local flora (macrophytes, diatoms) and fauna (molluscs, Cladocera) during the last ca. 3000 years; (ii) provide a background of local to regional vegetation composition and disturbance by fire and human impact in the Drava valleys. (iii) determine natural reference conditions as a basis for the restoration of degraded oxbow ecosystems in the region; Our study revealed that: (i) in the shallow eutrophic oxbow lakes (ca. 2 m deep) occurred numerous submerged ( Najas marina, N. minor, Ceratophyllum demersum, Zannichelia palustris) and floating macrophytes ( Trapa natans, Nymphaea alba, Nuphar lutea), Cladocera and molluscs species (e.g. Borysthenia naticinata, Bithynia tentaculata, Valvata cristata) and we recommend that these species should be included in the restoration of oxbows in this region; (ii) warm climate phases (Roman Period, Medieval Period) likely enhanced the terrestrialisation process and transformation of water reservoirs into peatlands between 1200 and 800 cal. BP; (iii) human activity has led to changes in overall forest composition, including riparian tree taxa, since the beginning of the record and has intensified since the Medieval Period; (iv) the difference in the time and intensity of fires between the northern and southern part of Drava river valley is most likely due to the different history of human colonisation.

Droughts and windstorms due to climate change increase variability in species and trait composition of a subtropical monsoon evergreen broadleaf forest in China

BackgroundClimate change is accelerating alterations in forest species and community composition worldwide, especially following extreme events like severe droughts and windstorms. Understanding these effects on subtropical forests is crucial for conservation and forest management, but it remains unclear whether the impacts are stochastic or deterministic. MethodsWe analyzed a unique dataset from a 1-ha permanent plot in a subtropical monsoon broadleaf evergreen forest in China, monitored over 26 years with six surveys from 1994 to 2020. The forest has been free from anthropogenic disturbances for over 400 years. In each survey, we measured all trees with a diameter at breast height (DBH) ​≥ ​1 ​cm, and recorded 11 plant functional traits relating to photosynthesis, wood properties, water use, and nutrient dynamics. Using this data, we calculated species and trait dispersion, assessing short-term (∼5 years) and long-term (26 years) trends in species and trait composition following severe droughts and windstorm events. ResultsSevere droughts, and subsequent droughts, increased both species and trait dispersion, while species composition converged, and trait dispersion remained relatively stable throughout the recovery period. Windstorm events led to increased species dispersion but decreased trait dispersion. We observed a clear directional shift in both species and trait composition under these climatic stressors, with a more pronounced increase in trait dispersion compared to species dispersion. ConclusionIn the short term (∼5 years), severe droughts and windstorms increased species composition divergence, while trait composition responses varied. Over 26 years, deterministic processes mainly drove community composition changes, especially for trait composition, although stochastic processes also played a role. These findings suggest enhancing forest resilience to climatic stressors by protecting adaptive species or increasing species diversity in management practices.

How did the diversity of woody plants in urban forests vary with the urban-rural gradient in Qingdao, China?

The distribution and diversity of woody vegetation are crucial for understanding the structure and ecology of urban forests. As urbanization accelerates, the construction and composition of urban forests vary significantly along the urban-rural gradient. Qingdao's urban forests offer an opportunity to test the relationship between the diversity of woody plants and the urban-rural gradient. We classified the urban-rural gradient using imperviousness and construction time, then investigated the diversity of woody plants in Qingdao's urban forests under different urban-rural gradients and tested the reasonableness of their allocation. Correlation analysis found that the diversity index of woody plants in urban forests was highly connected to the urban-rural gradient (by imperviousness: rMargalef Index = −0.589, rShannon-Wiener Index = -0.373, rPielouIndex = −0.170, rSimpson Index = 0.272/by construction time: rMargalef Index = −0.530, rShannon-Wiener Index = −0.360, rPielouIndex = −0.148, rSimpson Index = 0.272/0.174). With a decrease in urbanization density, the Margalef (H), Shannon-Wiener (H′), and Simpson (D) indices all decreased while the Pielou (E) index increased. The four diversity indices showed a substantial correlation with one another, but not with the Margalef and Pielou indices. The analysis utilizing the 10/20/30 rule of empirical demonstrates a clear irrationality in allocating shrub species in Qingdao's urban forests, and the distribution of tree species is reasonable. Based on the study results, strategies for optimizing and enhancing urban forests in Qingdao are proposed for different urban-rural gradients, respectively. This study can provide a scientific framework for urban biodiversity conservation and management in Qingdao and serve as a guide for urban forests and greening with comparable climates.

Nitrogen deposition in the middle-aged and mature coniferous forest: Impacts on soil microbial community structure and function

The impact of nitrogen (N) deposition on soil microbial community structure and function has been a focal point of research; however, the influence of forest age and N form on the microbial response to N deposition has yet not to be fully understood. To address this gap, metagenomic sequencing was utilized to explore the responses of soil microbial community structure and functional genes to five years of N addition in middle-aged and mature coniferous forests in southwest China. Adopting a randomized block design, the experiment included two N forms ((NH4)2SO4 and KNO3) across four levels of addition (0, 10, 20 and 40 kg N ha−1 yr−1). Our findings reveal that the composition of the microbial community structure and functional genes involved in the carbon (C), N, phosphorus (P), and sulphur (S) cycling varied significantly between middle-aged and mature forest (P < 0.001). At the phylum level, the soil microbial community in the mature forest were dominated by Proteobacteria (30.4–38.8 %), Acidobacteriota (8.5–24.1 %), and Chloroflexota (8.1–21.5 %), and the soil microbial community in the middle-aged forest showed a greater presence of Acidobacteriota (28.9–34.0 %) and Actinobacteriota (13.3–19.2 %) with a lower proportion of Chloroflexota (0.4–1.2 %). In both middle-aged and mature forests, functional gene abundance, and the composition of microbial community and functional genes were unaffected by N addition rate (P = 0.793) and N form (P = 0.725). The taxonomic composition of soil microbial community in the mature forest showed a significant positive correlation with soil pH, soil organic carbon (SOC) and total nitrogen (TN) (P < 0.01), while the microbial community composition in the middle-aged forests was not significant correlated with soil pH, SOC and TN (P > 0.05). These findings underscore that N addition in the middle-aged and mature coniferous forest does not significantly impact the soil microbial community structure and function across different N forms and N addition rate, suggesting that soil microorganisms of the forest ecosystem exhibit strong resilience to increased N supply.

Woody plants diversity and the associated provisioning ecosystem services across three contrasting forest management regimes in Southwest Ethiopia

Woody plants are a source of provisioning ecosystem services. Coffee management impacts forest composition, structure, and diversity. We studied the effect of coffee management intensification on woody plants and their associated provisioning ecosystem services under three contrasting forest management regimes in southwest Ethiopia. The study employed mixed approaches (vegetation assessment and ethnoecological study) to collect the data. Woody plants were collected from 189 plots and perceived local ecosystem services were identified by 136 individuals through an ethnoecological approach. The total number of woody plants recorded in the natural forest, coffee forest, and coffee agroforest was 971, 945, and 521 respectively. Species richness in natural forest, coffee forest, and coffee agroforest were 57, 54, and 53 respectively. The local people perceived 17 different provisioning ecosystem services collected from the three forest types. The result showed that there is a positive relationship between the diversity and use value of woody plants across the three forest management regimes. Coffee management intensification simplifies the stand structure, woody plant composition, and ecosystem services of the forest. Plant use value increases in coffee agroforests. Coffee agroforests can serve as repositories of diversity and ecosystem services in southwest Ethiopia.

Impact of the extreme 2015-16 El Niño climate event on forest and savanna tree species of the Amazonia-Cerrado transition

Extreme drought events, driven by the El Niño Southern Oscillation (ENSO), are linked to increased tree mortality and alterations in vegetation structure, dynamics, and floristic composition in tropical forests. Existing analyses, primarily focusing on Africa, Central America, and Amazonia, overlook the floristic impacts on biome transitions. This study evaluates the profound effects of the severe 2015/2016 ENSO event on tree density and floristic composition in the critical transition zone between Amazonia and Cerrado, South America's largest biomes. Our findings not only document significant biodiversity loss but also offer insights into species resilience, guiding conservation strategies under changing climate conditions. We inventoried long-term plots before and after the extreme drought event, sampling 12,465 individuals from 526 species, 224 genera, and 65 families, in Open Ombrophilous Forest (OF), Seasonal Forest (SF), Cerradão (CD), and Typical Cerrado (TC). We document the disappearance from our plots of 97 species after the ENSO, with only 61 new species being recorded. The total loss of individuals across the transition zone was almost 10 %. The SF and CD forest plots showed the greatest replacements, species losses, and reductions in tree density. Their markedly seasonal baseline climate probably drove these changes. In most phytophysiognomies, there was an increase in pioneer species and drier environment habitat specialist species, indicating that although many species are vulnerable to extreme climate events, others benefit, especially those with a short life cycle. We found that the vegetation of the Amazonia-Cerrado transition overall is vulnerable to climate anomalies, with widespread loss of tree density and change in floristic composition. Our study also provides a species-by-species list of the most vulnerable and resistant trees which helps point to overall climate change vulnerabilities and assist with initiatives to recover degraded areas.

Effects of fire on tree species composition and carbon stocks of a peat swamp forest in Central Kalimantan, Indonesia

ABSTRACT Peat swamp forests are important in the global carbon (C) budget because of the huge amount of C stored in these ecosystems, particularly in below-ground components. Indonesia has some of the greatest extent of peat swamp forests globally, yet many of them are being disturbed by fires that are becoming increasingly frequent. In Kalampangan, Central Kalimantan, the tree species (≥4.8 cm diameter) composition, aboveground biomass (AGB) and litter standing crop of peat swamp forests were sampled, and the overall ecosystem C stock estimated, within two 1-ha sampling plots, one of which was undisturbed (natural) and the other previously burned. The AGB and litter standing crop found in the natural forest totaled 341 and 6.77 Mg ha−1, respectively. The AGB declined more than six-fold to 53.2 Mg ha−1, and the litter standing crop declined by about half to 3.30 Mg ha−1 in the disturbed forest; the total number of tree species declined from 114 to 80 per hectare. The disturbed peat swamp lost just over 200 Mg C ha−1 to the atmosphere due to the combustion of tree biomass and the upper layer of the peat, but C stocks still remained very high overall (c. 1100 Mg ha−1) due to the thick layer of peat (>2 m) making peat swamp forest conservation imperative due to their huge carbon stocks.

An Interseasonal Comparison of Soil Respiration in Xeric and Mesic Pine Forest Ecosystems in Central Siberia

An understanding of how boreal forest composition responds to global environmental changes is an important challenge to predicting the future global carbon balance. Boreal forests are the most significant sink for atmospheric carbon dioxide; however, their sequestration capacity is highly sensitive to ongoing climate changes. The combination of the hydrothermal conditions of a territory strongly regulates its biogeochemical processes. The carbon fluxes in boreal forests are strongly mediated by the ground vegetation cover, composed of mosses (mesic) and lichens (xeric). Despite the concurrence of xeric and mesic vegetation types, their responses to climate variations varies significantly. Soil emission is an informative indicator of ecosystem functioning. In this study, we focused on the soil CO2 dynamics during frost-free seasons with different precipitation regimes in the xeric and mesic boreal ecosystems of Central Siberia. Seasonal measurements of soil CO2 emissions were conducted during frost-free seasons using the dynamic chamber method. Our findings reveal that the precipitation regimes of each year may control the seasonal soil emission dynamics. The soil moisture is the most important driver of emissions growth in the water-limited lichen pine forest (R2adj. = 18%). The soil temperature plays the largest role in the feather moss pine forest during the dry (R2adj. = 31%) seasons, and in the lichen pine forest during the wet (R2adj. = 41%) seasons. The cumulative efflux for the xeric and mesic sites is mostly related to the hydrothermal conditions, and not to the differences in ground vegetation cover. During the dry seasons, on average, the soil CO2 emissions are 45% lower than during the wet seasons for both sites. These findings emphasize the need for estimating and including the hydrothermal characteristics of the growing season for detailed emission assessments.

Composition of Paleocene forests from Antarctica based on fossil wood

A new assemblage of fossil wood of Paleocene age from Seymour Island, Antarctic Peninsula, is described. Conifer species have been identified, belonging to the fossil genera Agathoxylon, Phyllocladoxylon, Protophyllocladoxylon, and Podocarpoxylon. Angiosperm fossil wood species are assigned to Nothofagoxylon, Caldcluvioxylon, and Myrceugenellites. New wood types have been described with possible affinity to Atherospermataceae and Asteraceae (daisy family). A newly identified fossil angiosperm species, Aextoxicoxylon jacksius, has been recorded from Antarctica for the first time. It shares traits with modern Aextoxicon punctatum and other Aextoxicoxylon wood from South America but is considered a separate species due to significant differences in vessel density, ray height, and frequency. This study indicates, in accordance with previous studies that conifers were the most common elements in the Paleocene Antarctic vegetation. In particular, Agathoxylon being the most dominant wood type. Nothofagoxylon was the most common angiosperm wood type. Overall the composition of the Antarctic Paleocene vegetation deduced from the presence of fossil wood resembles that of the modern warm to cool temperate forests of Tasmania, New Zealand and southern South America. Possible upland and lowland forest types have been identified, with the lowland forests likely most similar to the modern mixed cool temperate forests on South Island, New Zealand, and Tasmania. The upland forests were similar to the modern open canopy Araucaria-Nothofagus forests on the high Andes today.

Achieving structural heterogeneity and high multi-taxon biodiversity in managed forest ecosystems: a European review

AbstractThe European Biodiversity Strategy has set the key goal to maintain and promote biodiversity. Managed forests here play a key role, as they are among the most diverse ecosystems. To create biodiversity rich managed forest landscapes, we need a deep understanding on how management affects forest structure and subsequently habitat quality on the local and landscape level. However, to date a confusingly large amount of different terms for various management systems exist and it remains unclear how forest structure and composition affected by specific management systems affect biodiversity. Here, we first aim to clarify forest management systems terminology. Second, we link existing management systems with forest structure and review at European level how these structures affect local α-, as well as landscape-scale β- and γ-biodiversity. We found that research and derived management guidelines have a strong focus on local forest stand heterogeneity and related α-diversity, while ignoring the importance of landscape-scale heterogeneity and therefore β- and γ-diversity. Instead of promoting one management system as an all-in-one-solution, a diversity of different forest management systems seems the most promising way to create biodiversity rich forest landscapes. We finally discuss how a combination of different management systems might help to create structurally rich forest habitats and landscapes, simulating different successional stages and promoting species rich communities.

Association of Carbon Pool with Vegetation Composition along the Elevation Gradients in Subtropical Forests in Pakistan

As the most important way to mitigate climate change, forest carbon storage has been the subject of extensive research. A comprehensive study was carried out to investigate the influence of elevation gradients and diameter classes on the forest growth, composition, diversity, and carbon pools of the Bagh Drush Khel Forest area. Research revealed that elevation gradients significantly influenced the composition, diversity, and carbon pools in forests. At lower elevations, Eucalyptus camaldulensis was the dominant species, with Olea ferruginea as a co-dominant species, whereas at higher elevations, Pinus roxburghii was the dominant species with Quercus incana as a co-dominant species. Regeneration was higher at higher elevations with the maximum number of saplings and seedlings of P. roxburghii. Species diversity association with elevation was negative (R2 = −0.44; p &lt; 0.05—Shannon Index). Soil organic carbon (SOC association with elevation was non-significant while positive with DBH classes (R2 = 0.37; p &lt; 0.05). Overall, carbon pool association with elevation and diameter at breast height (DBH) were negative (R2 = −0.73; p &lt; 0.05) and (R2 = −0.45; p &lt; 0.05). Litter biomass correlated positively with elevation (R2 = 0.25; p &lt; 0.05) and DBH (R2 = 0.11; p &lt; 0.05), while deadwood biomass correlated negatively with elevation gradients (R2 = −0.25; p &lt; 0.05), and no effect was observed for DBH classes. The highest carbon stock (845.89 t C/ha) was calculated at low elevations, which decreased to (516.27 t C/ha) at high elevations. The overall carbon stock calculated was (2016.41 t C/ha) respectively. A total of six tree species were found at the study site. Future research is essential for forest health monitoring and understanding fine-scale impacts. This study offers a methodological framework for similar investigations in unexplored yet potentially significant forest regions worldwide.

Multi-objective optimization of forest structure for broadleaf mixed forest under different CMIP5 scenarios

Climate change is an important global research topic and one of the most pressing issues facing the world today. It significantly impacts forest distribution, species composition, stand structure, growth, and other functions, therefore, it is crucial to simulate the dynamic changes of forest structure under future climate change and develop optimized solutions to adapt to it. Combined with the various stand structural parameters, based on the equal or unequal weights of each parameter at the stand level, to establish a dynamic stand spatial structure multi-objective optimization index (L-index) under different climate changes, and to implement broadleaf mixed forest spatial structure optimization research in Yanan Forest Farm under RCP 2.6, RCP 4.5, RCP 8.5 climate scenarios after 5 years. The results indicated that the L-index showed an increase ranging from 13.8 % to 35.7 % under equal weights in different climate scenarios. Additionally, the optimal harvesting intensity ranged from 13.2 % to 20.5 %, with the highest intensity observed in the RCP4.5 climate scenario; compared to the RCP4.5 and RCP8.5 climate scenarios, the RCP2.6 scenario shows the largest trend and magnitude of change in the indicators, suggesting that the state of stand growth is more sensitive under the RCP2.6 scenario. The L-index showed an increase ranging from 13.7 % to 34.4 % under the unequal weights in different climate scenarios, in which the optimal harvesting intensity ranged from 14.6 % to 19.8 %. More importantly, it should be noted that the values of the increases in the L-index and the relative increased proportion (RIP) were both higher than those when unequal weights were employed. Moreover, it should be highlighted that the increments in the L-index and RIP were both greater than those observed when unequal weights were applied for all three plots under different climate scenarios. Overall, the adjusted the complete mixing degree index (Mc) increased, angle index (W), dominance ratio index (U), and Hegyi competition index (CI) decreased compared to before optimizing with the equal or unequal weights of the stand structural variable, which is evident that the adjustments made to the stand’s structure have resulted in a significant improvement. Thus, the multi-objective optimization for forest spatial dynamics constructed is both reasonable and effective, and it more scientific forest management under different climatic scenarios.

Tree species richness and mycorrhizal types drive soil nitrogen cycling by regulating soil microbial community composition and diversity in tropical forests

A growing body of evidence indicates that tree mycorrhizal association and species richness pronouncedly affect soil nitrogen (N) cycling. However, most studies have been conducted in temperate forests, and the roles of soil microbial communities have been largely overlooked. Here, based on 11 long-term dynamic monitoring sites in tropical forests, we investigated the effects of the dominance of trees associated with arbuscular mycorrhizal (AM) (by basal area) and tree species richness on soil N cycling, and explored the role of soil bacteria, archaea and fungi. Our results showed contrasting effects of AM tree dominance and tree species richness, with AM tree dominance-induced increases in soil ammonium N, nitrate N and the rate of net N nitrification, and tree species richness-caused decreases in ammonium N, nitrate N, the rate of net N mineralization and ammonification. Moreover, we found that the “plant-soil-microbe” interactions mainly triggered the changes in net N mineralization, ammonification and nitrification. It was mainly bacterial composition that directly affected soil N mineralization and ammonification, while fungal diversity only changed soil N ammonification. For soil N nitrification, the abundance of ammonia-oxidizing archaea (AOA) was the main drivers. These findings reveal the discrepancy in effects of the AM tree dominance and tree species richness on soil N cycling, highlighting microbe-mediated mechanisms in regulating soil N mineralization, ammonification and nitrification.

Soil Legacies of Tree Species Composition in Mature Forest Affect Tree Seedlings’ Performance

AbstractTrees affect the biotic and abiotic properties of the soil in which they grow. Tree species-specific effects can persist for a long time, even after the trees have been removed. We investigated to what extent such soil legacies of different tree species may impact tree seedlings in their emergence and growth. We performed a plant–soil feedback experiment, using soil that was conditioned in plots that vary in tree species composition in Białowieża Forest, Poland. Soil was taken from plots varying in proportion of birch, hornbeam, pine, and oak. In each soil, seeds of the same four target species were sown in pots. Seedling emergence and growth were monitored for one growing season. To further explore biotic implications of soil legacies, ectomycorrhizal root tip colonization of oak, a keystone forest species, was determined. We found no effect of soil legacies of tree species on the emergence measures. We, however, found a clear negative effect of pine legacies on the total biomass of all four seedling species. In addition, we found relationships between the presence of pine and soil fertility and between soil fertility and root tip colonization. Root tip colonization was positively correlated with the biomass of oak seedlings. We conclude that tree species can leave legacies that persist after that species has been removed. These legacies influence the growth of the next generation of trees likely via abiotic and biotic pathways. Thus, the choice of species in today’s forest may also matter for the structure and composition of future forests.

Tidal Freshwater Forested Wetlands in the Mobile-Tensaw River Delta along the Northern Gulf of Mexico

Tidal freshwater forested wetlands (TFFWs) typically occur at the interface between upriver non-tidal forests and downstream tidal marshes. Due to their location, these forests are susceptible to estuarine and riverine influences, notably periodic saltwater intrusion events. The Mobile-Tensaw (MT) River Delta, one of the largest river deltas in the United States, features TFFWs that are understudied but threatened by sea level rise and human impacts. We surveyed 47 TFFW stands across a tidal gradient previously determined using nine stations to collect continuous water level and salinity data. Forest data were collected from 400 m2 circular plots of canopy and midstory species composition, canopy tree diameter and basal area, stem density, and tree condition. Multivariate hierarchical clustering identified five distinct canopy communities (p = 0.001): Mixed Forest, Swamp Tupelo, Water Tupelo, Bald Cypress, and Bald Cypress and Mixed Tupelo. Environmental factors, such as river distance (p = 0.001) and plot elevation (p = 0.06), were related to community composition. Similar to other TFFWs along the northern Gulf of Mexico, forests closest to Mobile Bay exhibited lower basal areas, species density, diversity, and a higher proportion of visually stressed individual canopy trees compared to those in the upper tidal reach. Results indicate a strong tidal influence on forest composition, structure, and community-level responses.

Understanding Tree Mortality Patterns: A Comprehensive Review of Remote Sensing and Meteorological Ground-Based Studies

Land degradation, desertification and tree mortality related to global climate change have been in the spotlight of remote sensing research in recent decades since extreme climatic events could affect the composition, structure, and biogeography of forests. However, the complexity of tree mortality processes requires a holistic approach. Herein, we present the first global assessment and a historical perspective of forest tree mortality by reviewing both remote sensing and meteorological ground-based studies. We compiled 254 papers on tree mortality that make use of remotely sensed products, meteorological ground-based monitoring, and climatic drivers, focusing on their spatial and temporal patterns and the methods applied while highlighting research gaps. Our core results indicate that international publications on tree mortality are on the increase, with the main hotspots being North America (39%) and Europe (26%). Wetness indicators appear as the barometer in explaining tree mortality at a local scale, while vegetation indicators derived from multispectral optical sensors are promising for large-scale assessments. We observed that almost all of the studies we reviewed were based on less than 25 years of data and were at the local scale. Longer timeframes and regional scale investigations that will include multiple tree species analysis could have a significant impact on future research.

Sapling recruitment as an indicator of carbon resiliency in forests of the northern USA.

Tree regeneration shapes forest carbon dynamics by determining long-term forest composition and structure, which suggests that threats to natural regeneration may diminish the capacity of forests to replace live tree carbon transferred to the atmosphere or other pools through tree mortality. Yet, the potential implications of tree regeneration patterns for future carbon dynamics have been sparsely studied. We used forest inventory plots to investigate whether the composition of existing tree regeneration is consistent with aboveground carbon stock loss, replacement, or gain for forests across the northeastern and midwestern USA, leveraging a recently developed method to predict the likelihood of sapling recruitment from seedling abundance tallied within six seedling height classes. A comparison of carbon stock predictions from tree and seedling composition suggested that 29% of plots were poised to lose carbon based on seedling composition, 55% were poised for replacement of carbon stocks (<5 Mg ha-1 difference) and 16% were poised to gain carbon. Forests predicted to lose carbon tended to be on steeper slopes, at lower latitudes, and in rolling upland environments. Although plots predicted to gain and lose carbon had similar stand ages, carbon loss plots had greater current carbon stocks. Synthesis and applications. Our results demonstrate the utility of considering tree regeneration through the lens of carbon replacement to develop effective management strategies to secure long-term carbon storage and resilience in the context of global change. Forests poised to lose C due to climate change and other stressors could be prioritized for regeneration strategies that enhance long-term carbon resilience and stewardship.

Understanding the influence of environmental factors on forest composition along the vertical gradient of Northwestern Himalaya

Temperate and alpine ecosystems are considered the most sensitive and vulnerable region towards climate change in the Indian Himalayan region. The current study investigates forest composition in relation to environmental and edaphic factors, which is critical for determining plant community patterns. The impact of climatic and soil properties was studied to better understand species diversity and composition over an elevational gradient (2500–4800 m) in Beas Valley, Northwestern Himalaya. A total of 181 species from 15 community types, representing 122 genera and 53 families (9 Trees, 13 shrubs, and 142 herbs) were recorded from the valley. Non-metric multidimensional scaling (NMDS) analysis revealed significant compositional dissimilarity (PseudoF = 10.16, R2 = 0.48, p < 0.001) among vegetation types. Structural equation modeling (SEM) results indicated that tree species diversity was significantly influenced by solar radiation (β=0.17, p = 0.001) and winter temperature (β=41.95, p = 0.017). It was observed that solar radiation and winter temperature shape the community types in high elevation temperate regions. In contrast, precipitation, solar radiation along with summer temperature determine the composition of sub-alpine communities, whereas solar radiation, winter temperature and soil pH determine the composition of alpine communities. This indicated that multiple environmental factors are responsible for this diversity. The research findings shed light on crucial factors influencing high elevation plant diversity, emphasizing the significance of understanding environmental correlations for effective conservation. This is pioneer study, which will act as a reference for future studies in Beas valley. This scientific foundation allows for prioritized conservation efforts, focusing on areas with specific environmental conditions influencing forest composition and plant diversity, ultimately contributing to better management and preservation of high elevation plant communities.

Effect of climate change on current and future potential distribution of Strawberry tree (Arbutus unedo L.) in Türkiye

The demand for nontimber forest products (NTFPs) has increased significantly in recent years. Hundreds of plant species that grow naturally in Türkiye have medicinal and aromatic value. Medicinal and aromatic plants are primarily used as a sources of tea, spices, condiments and essential oils. Species belonging to the genus Arbutus L. are used for decorative purposes and as fuel wood in many wood-based industries, they also have a wide range of uses in packaging, chairs making and furniture production. Additionally, the fruits of these trees are widely consumed by humans and animals because they are rich in sugar and vitamin C. It is predicted that changes in climatic conditions will significantly change the distribution, composition and function of forests threatening biodiversity. The purpose of this study was to model current and future potential geographical distributions of Arbutus unedo L., which is among the species that naturally grow in Türkiye and is of substantial value in terms of its ecological contribution to forest ecosystems, based on species presence data and environmental variables (bioclimatic variables and altitude). The current and future distribution area models for Arbutus unedo L. indicate that the potential distribution areas of the species in the coming years will gradually decrease, and in the SSP5 8.5 model, which represents the highest level of world resource usage this gradual decrease will reach its highest level and there will be no suitable distribution area left for the species. Therefore, it is predicted that the species will become endangered. In-situ and ex-situ conservation measures need to be taken to ensure the sustainability of the species in forestry and landscape areas.