National Forest Research Articles

1110. Hibiscus glaber Matsum. ex Nakai: Malvaceae

SummaryHibiscus glaber is a symbolically significant endemic species found exclusively on the Ogasawara (Bonin) Islands. It is one of the main tree species in the natural forests of the island. This species is illustrated here, and its natural history, ecology, pollination, and cultivation are described.

Kimboza, a Small Lowland Forest With an Outstanding Herpetofauna Diversity in East Africa.

The Eastern Arc Mountains (EAM) and Coastal forests of Tanzania are renowned for harboring large number of threatened and endemic vertebrate species, yet most of these areas have been partially studied. The Kimboza Nature Forest Reserve (KNFR) is a small forest which is in transition between the EAM and Coastal forests, and among the poorly surveyed areas for amphibians and reptiles. We conducted systematic surveys across the KNFR in 2012 and between 2020 and 2023 using a range of approaches with the aim of establishing a comprehensive and updated list of reptile and amphibian species and assess the contribution of EAM and Coastal forests to the KNFR's herpetofauna. We identified 77 species, 29 amphibians and 48 reptiles, substantially updating previous species lists. Three of these species (Kinyongia magomberae, Trachylepis boulengeri and Philothamnus macrops) represent range extensions from previously known ranges. Fourteen species are endemic to East Africa, 11 of them being restricted to Tanzania. These results make the KNFR the richest forest reserve for herpetofauna per square km in Tanzania, and most similar in its composition to the Coastal, rather than Eastern Arc forests. With the caveats concerning taxonomic uncertainties and the inequalities of sampling intensity across the region, this study shows that the KNFR is an important area that deserves conservation attention. The KNFR, like other Coastal forests, is under significant pressure from anthropogenic activities which call for an urgent action to protect this small but rich forest.

The Importance of Regenerating Forests for Biodiversity Conservation: Insights From Bird Communities

Biodiversity is crucial for ecological research and ecosystem function, but human activities have led to widespread habitat loss and threats to biodiversity. Recent studies challenge the belief that only primary forests preserve biodiversity, as 20-year-old secondary forests can exhibit comparable levels. We emphasize the significance of studying regenerating and human-altered forests. Our research explores the impact of such forests on avian communities, focusing on different habitat and forest types. Using Non-metric Multidimensional Scaling and Analysis of Similarities, we analyze bird community composition across various habitats. The Parker index and Analysis of Variance evaluate bird sensitivity to habitat changes. Results indicate significant differences in bird communities and sensitivity based on forest and habitat types. The study provides insights into forest integrity, contributing to improved conservation practices in regenerating and human-altered forests. Limitations include assumptions due to limited fragmented plots, suggesting avenues for future research to enhance forest regeneration efforts.

Species Richness, Abundance, and Vertical Distribution of Epiphytic Bromeliads in Primary Forest and Disturbed Forest.

Epiphytes represent a key component in tropical forests. They are affected by anthropogenic and natural disturbances suffered by forests, since they depend on their hosts and the microclimatic conditions they generate. We analyzed differences in abundance, species richness, and vertical distributions of epiphytic bromeliads in primary and disturbed forests. We found a higher abundance (5316 individuals) and species richness (8 species) of bromeliads in disturbed forest than in primary forest (1360 individuals and 4 species, respectively). Most bromeliads (97%) were found on Taxodium mucronatum, a dominant tree with rough bark in the disturbed forest (gallery forest). Bromeliads were more abundant in the middle of the tree and diminished towards the trunk base and the upper crown. Tillandsia baileyi was the most abundant bromeliad, and the size categories of this species differentially colonize trees in gallery forest according to Johansson zones; seedlings of T. baileyi abundantly colonize the upper canopy, and juveniles colonize the middle canopy or secondary branches. Gallery forest represents an important reservoir for epiphytic bromeliads. Hence, it is important to extend this kind of study to wetland sites to understand the role they play as a habitat for epiphytes, as well as the dynamics and ecological processes that occur in such habitats.

Divergent Importance and Geographic Patterns in Threats to Birds and Mammals in China

ABSTRACTAimWildlife populations are continuing to decrease worldwide. Understanding the ranking and distribution of drivers of species declines is crucial to enable targeted actions to counteract major threats. However, few studies have assessed the relative importance and geographic distribution of threats to biodiversity in China, even for high‐profile groups such as birds and mammals. Therefore, this study aims to rank and map the distribution of threat to birds and mammals in China, which could provide novel insight into biodiversity conservation in China.LocationChina.MethodsA database of different threats for 147 threatened bird species and 176 threatened terrestrial mammal species was obtained from China's Red List of Biodiversity published in 2021. We collated information on the distribution and threat categories for birds and mammals in China, aiming to classify, rank and map threats. We used Bray–Curtis dissimilarity index to examine the correlations of threats occurring simultaneously, and compared the distribution of habitat of threatened birds and mammals. In addition, we conducted threat ranking analyses of threatened birds and mammals between different orders and traits (body mass and clutch/litter sizes).ResultsThe results showed that the most common threats to birds were habitat loss, hunting, human disturbance, agriculture, pollution and logging, while the most common threats to mammals were hunting, agriculture, logging, habitat loss, human disturbance and livestock farming or ranching. These threats showed different geographic patterns, and some threats frequently co‐occur as threat syndromes. Forests were the primary habitat for most threatened species, and orders formed by larger species with small clutch or litter sizes were more likely to be threatened.Main ConclusionsWe highlight the most common threats and key areas for conservation. Furthermore, focusing on clusters of co‐occurring threats may be the most effective way to aid recovery of threatened species, and targeted actions are needed to counter ongoing population declines in many groups. These actions should not be limited to the protection of regions where species are at risk of multiple significant threats, but should also include the maintenance and restoration of native forests and strategic planning of afforestation through planted forests.

A Dataset for Species Distribution Modelling of Mangroves in Vietnam: Based on the National Forest Inventory Monitoring

Mangroves provides essential ecosystem services such as protection of coastal areas, carbon sequestration, and habitat provision for diverse species in coastal ecosystems. Species distribution models (SDMs) are powerful tools for predicting the potential distribution of mangrove species, which support impact assessments of climate changes on biodiversity and ecological functions of mangrove ecosystems. A comprehensive dataset for mangrove occurrence information derived from the Forest Inventory Map of Vietnam was designed to facilitate the building and projection of SDMs. The prediction data designed for training SDMs integrates ecological information including 701 field survey-based mangrove occurrences at the genus level and 21 environmental variables such as bioclimatic variables, digital elevation model and soil properties with 1 km spatial resolution. The projection data for provide sets of predictors aligned with four shared socioeconomic pathways scenarios representing two future periods to support the projection of SDM results under future climate conditions in Vietnam. This dataset serves as a valuable ecological information resource, enabling the modeling and predicting of potential mangrove habitats and distributions for the protection and restoration of mangroves in Vietnam under changing environmental conditions.

Modeling aboveground carbon stock under the forest canopy influence

The dominance, size, and sociological position of tree species are essential components of natural forest patterns, providing critical information for understandinh forest dynamics. These patterns can be influenced by a variety of factors. This study aimed to evaluate the effectiveness of using spectral, hydrological, and geographical variables to estimate aboveground carbon stock (AGC) across four canopy strata, defined by diametric percentiles, in a Brazilian Atlantic Forest remnant. Our methodology, which employed machine learning techniques (Random Forest - RF + Genetic Algorithm - GA) and Multiple Linear Regression (MLR) to model AGC, proved to be highly efficient, as evidenced by our results. We observed a wide range of AGC values, from 0.37 to 467.71 MgC.ha-1, with an average of 77.4 MgC.ha-1. Trees in the 30th, 60th, and 90th percentiles contributed, respectively, 97.32%, 87.74%, and 52.02% of the total AGC. Spectral and hydrological variables combined with basal area explain AGC stock. Our findings demonstrate the robustness of machine learning techniques and MLR methods in obtaining accurate carbon estimates and generating an optimized dataset. Trees within the 30th percentile represent a smaller portion of the total AGC, and their removal does not interfere with the relationship between AGC and spectral variables.

Phytogeographical and biological spectrum of vascular flora as an indicator of ecological changes following clear-cutting in Eastern Serbian beech forest sites

Extreme weather events caused considerable harm to the forest ecosystems in Eastern Serbia over a few hard winters, resulting in widespread ice breaks and ice uprooting. Certain forest stands were severely impacted during the winter of 2014-2015, necessitating clear-cutting measures. This research was conducted in the Timok forest area, through examination of the floristic composition in areas subjected to clear-cutting, including natural beech forests and artificially established conifer stands within beech sites (Helleboro odori-Fagetum moesiacae). A phytogeographical and bioecological analysis was conducted five years after clear-cutting. Changes in ecosystems were assessed by analysing the spectra of area-types and plant life forms, with comparisons drawn to the “Vinatovača” old-growth forest, situated in the submontane beech forest of Eastern Serbia. Descriptive analysis of the phytogeographical and bioecological spectra of vascular flora, alongside multinomial correspondence analysis, revealed an increased presence of species from Eurasian, Mediterranean-sub-Mediterranean, and Pontic area-types, as well as hemicryptophytic, phanerophytic, and therophytic life forms in the clear-cut areas. In contrast, the old-growth forest was colonised by species of Central European and Holarctic area-types, along with geophytic life forms. These findings suggest a shift towards xerothermic microclimates in the clear-cut areas and the stronger influence of the continental climate of Eastern Serbia with its extremes on deforested areas, as well as on the processes of forest ecosystem degradation.

Species Richness and Similarity of New Zealand Mayfly Communities (Ephemeroptera) Decline with Increasing Latitude and Altitude.

The distribution of species in relation to latitude and altitude is of fundamental interest to ecologists and is expected to attain increasing importance as the Earth's climate continues to change. Species diversity is commonly greater at lower than higher latitudes on a global scale, and the similarity of communities frequently decreases with distance. Nevertheless, reasons for such patterns are not well understood. We investigated species richness and changes in community composition of mayflies (Ephemeroptera) over 13 degrees of latitude at 81 locations throughout New Zealand by light-trapping and the benthic sampling of streams. Mayflies were also sampled along an altitudinal gradient on a prominent inactive volcano in the east of North Island. Sampled streams were predominantly in the native forest, at a wide range of altitudes from sea level to c. 1000 m a. s. l. A total of 47 of the 59 described New Zealand mayflies were recorded during the study, along with five undescribed morphospecies. Species richness declined and the degree of dissimilarity (beta diversity) of mayfly communities increased significantly from north to south but less strongly with increasing altitude. Our results suggest that the southward decline in species richness has historical origins with the north of the country having acted as a major refuge and region of speciation during the Pleistocene. The increasing dissimilarity of the northern and southern communities may reflect an increasingly harsh climate, variable amounts of subsequent southward dispersal of northern species and, in the South Island, the presence of species which may have evolved in the newly uplifted mountains during the Miocene-Pliocene.

The Impact of Tourists’ Perceived Value on Environmentally Responsible Behavior in an Urban Forest Park: The Mediating Effects of Satisfaction and Subjective Well-Being

Urban forest parks serve as significant venues for tourists’ leisure and recreation. The experiences and perceptions of tourists in these parks considerably influence their attitudes and behaviors. While numerous studies have investigated the functions and values of urban forest parks at a macro level, the mechanisms influencing tourists’ perceived values and their environmentally responsible behavior at a micro level remain under explored. This research used structural equation modeling (SEM) to test the association between tourists’ perceived values and their environmentally responsible behavior, including the mediating functions of tourists’ satisfaction and their subjective well-being. 502 valid questionnaires in total were obtained from Changpoling National Forest Park in Guiyang City, Guizhou, China, for this case study. The results show that there are some variances in the impact of the dimensions of tourists’ perceived value on environmentally responsible behavior, in which service quality, resource quality, and emotional value impose a pronounced positive effect on environmentally responsible behavior, tourism costs impose a pronounced negative effect on environmentally responsible behavior, and the activity experience does not exert a pronounced effect on environmentally responsible behavior. Satisfaction and subjective well-being have a mediating function during the process of positive influence of tourists’ perceived value on their environmentally responsible behavior and serve as partial mediators, and the significant positive influence of satisfaction on subjective well-being as well as subjective well-being on environmentally responsible behavior are verified. This research can help better explain the mechanism of the effect of tourists’ perceived value exerted on environmental responsibility behavior in nature-based tourism destinations, and also has a guiding and reference significance for the sustainable development of urban forest parks.

Timber Harvest Planning Using Reinforcement Learning: A Feasibility Study

This study developed a forest management plan model using reinforcement learning (Q-learning) to optimize both the economic and ecological functions of forests. Management objectives for national forests were established, and forest conditions were analyzed using GIS spatial data and administrative records. A 60-year forest management plan was formulated to predict timber production and management performance across different regions and time periods. Our analysis revealed that Scenario 3 (Carbon Storage Priority) demonstrated the highest economic value, starting at approximately KRW 576.2 billion in the initial period and escalating to KRW 775.7 billion over six 10-year periods, totaling 60 years. In addition to its economic performance, Scenario 3 effectively improved forest age class structure and ensured a stable timber supply, making it the most balanced approach for sustainable forest management. By focusing on carbon storage as a key management goal, this approach highlights the potential for achieving both economic and environmental benefits concurrently. These results suggest that reinforcement learning is a powerful tool for developing long-term forest management strategies that address multiple objectives, including economic viability, ecological sustainability, and resource optimization.

Predicting the drivers of Bothrops snakebite incidence across Brazil: A Spatial Analysis

Snakebite envenoming poses a significant public health challenge on a global basis, affecting millions of people annually and leading to complications that may result in fatalities. Brazil stands as one of the countries most impacted by snakebite envenoming, with snakes of the Bothrops genus being responsible for most bites. The current study aimed to identify the determinants of Bothrops snakebite incidence across different regions of Brazil. An ecological study was conducted using municipality-aggregated data, with snakebite incidence as the dependent variable. The study period comprised the years 2015–2021. We constructed Species Distribution Models (SDMs) for Bothrops species, and information was collected on precipitation, runoff, maximum and minimum temperatures, native forest, historical forest loss, agriculture, and pasture in each Brazilian municipality. These data were employed to assess the association between snakebite incidence and biotic, climatic, and landscape factors. The data were analyzed using Generalized Least Squares (GLS) regression. The SDMs demonstrated good performance. The average annual snakebite incidence during the study period ranged from zero to 428.89 per 100,000 inhabitants, depending on the municipality. Higher incidence rates were concentrated primarily in municipalities in the northern region of the country. In this study, we found that nationwide, areas with extensive native forests and those that have historically experienced significant loss of forest cover exhibited higher snakebite incidence rates. Additionally, areas with higher temperatures and precipitation levels, as well as greater climatic suitability for the species B. jararaca, showed significantly higher snakebite incidence rates in the South and Southeast of Brazil, respectively. These associations may be linked to increased snake abundance and active behavior, as well as to engagement in activities favoring human-snake contact in these areas. The findings of this study can contribute to the improvement of prevention and control strategies for this public health issue in Brazil.

Ghost species form an important component of the epiphytic lichens in temperate forests

Sequencing of environmental samples has great potential for biodiversity research, but its application is limited by the lack of reliable DNA barcode databases for species identifications. Such a database has been created for epiphytic lichens of Europe, allowing us to compare the results of environmental sequencing with standard taxonomic surveys. The species undetected by taxonomic surveys (what we term the ghost component) amount to about half of the species actually present in hectare plots of Central European forests. Some of these, which currently occur only as diaspores or weakly developed thalli, are likely to be favoured in the course of global change. The ghost component usually represents a larger fraction in managed forests than in old-growth unmanaged forests. The total species composition of different plots is much more similar than suggested by taxonomic surveys alone. On a regional scale, this supports the well-known statement that “everything is everywhere, but, the environment selects”.

Nitrogen deposition contributed to a global increase in nitrous oxide emissions from forest soils

Nitrous oxide is a potent greenhouse gas. Anthropogenically enhanced nitrogen deposition causes natural forest soils to release more nitrous oxide, exacerbating global warming. We used data from nitrogen addition experiments conducted in forests worldwide to quantify the spatially varying sensitivity of soil nitrous oxide emission to nitrogen deposition, thereby inferring soil nitrous oxide emission dynamics from nitrogen deposition data. From 1985 to 2015, nitrous oxide emitted from global forest soils increased from 3.55 to 3.85 teragrams of nitrogen per year. Nitrogen deposition contributed directly to 9.0% of global forest soil nitrous oxide emissions. The derived country-specific sensitivities of soil nitrous oxide emission to nitrogen deposition could be employed as localized emission factors for forestland nitrous oxide emission inventories. This study sheds light on a process-augmented data-driven approach to estimating global nitrous oxide emissions by synthesizing experimental and observational data.

Planted Forests Greened 7% Slower Than Natural Forests in Southern China Over the Past Forty Years

AbstractForests have seen a strong greening trend worldwide, and previous studies have attributed this mainly to land‐use conversions such as afforestation. However, for the greening of existing forests, the role of human interventions is unclear. Here we paired neighboring natural and planted forests in Southern China to minimize the differences between the forest types and analyzed the vegetation index EVI2 from Landsat over 1987 to 2021. The EVI2 trends observed in natural forests can be seen as mainly responses to large‐scale environmental changes, whereas the difference between the forest types represents the impact caused by human interventions. We found that though the mean EVI2 of planted forests was comparable to that of natural forests, the greening trends were overall 7.0% lower in planted forests. Our results suggest that human interventions associated with planted forests did not accelerate their greening, indicating the necessity for refined policies to enhance future forest greening.

Assessing the role of natural kelp forests in modifying seawater chemistry

Climate change is causing widespread impacts on seawater pH through ocean acidification (OA). Kelp forests, in some locations can buffer the effects of OA through photosynthesis. However, the factors influencing this variation remain poorly understood. To address this gap, we conducted a literature review and field deployments of pH and dissolved oxygen (DO) loggers within four habitats: intact kelp forest, moderate kelp cover, sparse kelp cover and barrens at one site in Port Phillip Bay, a wind-wave dominated coastal embayment in Victoria, Australia. Additionally, a wave logger was placed directly in front of the intact kelp forest and barrens habitats. Most studies reported that kelp increased seawater pH and DO during the day, compared to controls without kelp. This effect was more pronounced in densely populated forests, particularly in shallow, sheltered conditions. Our field study was broadly consistent with these observations, with intact kelp habitat having higher seawater pH than habitats with less kelp or barrens and higher seawater DO compared to barrens, particularly in the afternoon and during calmer wave conditions. Although kelp forests can provide local refuges to biota from OA, the benefits are variable through time and may be reduced by declines in kelp density and increased wave exposure.

Historical pyrodiversity in Douglas-fir forests of the southern Cascades of Oregon, USA

Our understanding of forest dynamics and successional pathways in coastal Douglas-fir (Pseudotsuga menziesii var menziesii) forests with relatively frequent mixed-severity fires is limited by a lack of annually precise dendroecological reconstructions that combine records of historical fires and tree establishment. The processes by which old-forest heterogeneity developed under historical fire regimes with recurrent low- and moderate-severity fires has not been well studied at fine temporal scales and across spatial scales. We developed crossdated multi-century records of fire and tree establishment histories in old forests (170 – 550 years) at 34 plots distributed across six sites. Study sites include warm-dry to cool-moist Douglas-fir forest types found in the southern west Cascades of Oregon, USA. Spatial variability in historical fire frequency and fire effects resulted in tremendous diversity in forest developmental histories, age structure, and forest conditions. Most historical fire intervals were very frequent (<10 years) to frequent (<25 years) in dry Douglas-fir forests. Exceptionally high fire frequency and an abrupt decrease in fire frequency after European colonization in dry Douglas-fir forests adds to growing evidence and recognition of Indigenous fire stewardship in montane Douglas-fir forests. In moist forests where Douglas-fir is seral to western hemlock, fire intervals were frequent to moderately frequent (<50 years), but intervals varied substantially over time. Relatively young moist forests burned frequently while mature moist forests had long fire intervals (50–160 years). Nearly all tree establishment cohorts were preceded by either stand-replacing (28 %) or non-stand-replacing fires (64 %). However, tree cohorts only provided evidence of 16 % of historical fire events that we reconstructed from cambial fire scars. This study demonstrates that frequent fire can be an important driver of forest development and in some contexts shapes the structure of coastal old-growth Douglas-fir forests, which are often characterized as developing from endogenous disturbances during long fire-free periods. The high level of pyrodiversity we observed was associated with variation in and interactions of micro-climate, topography, fuels, and Indigenous fire stewardship. We recommend rigorous dendroecological reconstructions across the coastal Douglas-fir region to refine our understanding of the geography of fire-mediated forest developmental dynamics in this important forest type, to inform forest management, conservation, and ecocultural restoration.

How dominant height responds to mixing species: Effect of traits and height difference between species

Adapting forests to climate change is a major challenge for forest ecology and forestry. Among the management options available, encouraging the use of mixtures is a promising way forward. However, this practice requires a thorough understanding of how species respond to mixing. In this article, we analyzed species dominant height responds to mixing and how species ontogeny and traits drive this response. We compared species observed dominant height in mixed even-aged stands with the expected dominant height of the same species in a monospecific stand under the same environmental conditions. We then related this dominant height variation due to mixing to between-species dominant height difference and to species traits linked to competition (shade tolerance, wood density, specific leaf area).We focused our analyses on 76 pairs of forest tree species. We used data from the French National Forest Inventory to calculate species dominant height in 1368 mixed stands. We then used previously developed models to estimate the expected dominant height in virtual monospecific stands with the same environmental conditions.We found that mixture had a significant impact on species dominant height for 15 out of 50 species-combination considered. Dominant height of a given species was higher in mixture than in pure stands when this species had a lower dominant height in pure stands, a lower shade tolerance, a lower specific leaf area or a higher wood density than its companion species.Our results suggest that species dominant height response to mixing depends on how mixture influences the competition for light. Our results will help inform strategies aiming to diversify species in forests, and will be especially useful in anticipating a given species’ behavior in response to competition for light when it is mixed with other species.

Assessing the impact of urbanization on forest carbon stocks and social costs using a machine learning approach

Urbanization frequently precipitates urban sprawl, resulting in deforestation and alterations in landscape and land alterations. Such transformations profoundly impact the carbon stocks within metropolitan regions. This study examines the ramifications of urbanization on alterations in carbon stocks within urban forests across ten South Korean cities experiencing substantial urbanization over the past 15 years. Leveraging machine learning techniques and high-resolution satellite imagery, we scrutinize changes in land usage and urban forests, utilizing them to gauge the societal costs linked with shifts in urban carbon stocks. Furthermore, we integrate regional-level data sourced from national forests to enhance the precision of carbon stock estimations. Data analysis reveals that over the 15 years, urban areas expanded at an average rate of 4.43 km2 annually. In comparison, forested areas decreased by an average of −2.19 km2 per year, resulting in an average annual decline of −3171 tC in forest carbon stocks due to urbanization. The fluctuation in carbon stocks across the urban forests of the ten cities ranged from −68 % to 48 % over 15 years, primarily influenced by the extent of preserved forest area, with forest composition playing a secondary role. Concurrently, carbon sequestration efficiency varied between cities, ranging from 8 % to 57 % over 15 years, contingent upon tree type and forest age composition. An approximate loss of 174,380 tCO2eq of carbon stocks attributable to urbanization is estimated, with the associated social cost of increased emissions estimated at $8,893,396. Effective management of carbon emissions and sinks within urban locales is paramount for climate change mitigation, given the substantial contribution of urban areas to global carbon emissions. This study underscores the significance of urban forest management in carbon governance and furnishes valuable insights into nations undergoing rapid urban expansion.

Applying Reiss’ expectancy theory to locals’ perceptions of a potential red wolf reintroduction to Ozark National Forest, AR

ABSTRACT Although perceptions of risk related to wildlife have been well-studied, little research has evaluated the root causes of these perceived risks. Using a semi-structured instrument, we interviewed 20 interested parties who reside and/or recreate near Ozark National Forest, Arkansas, to explore perceptions of a potential red wolf (Canis rufus) reintroduction to the region. We employed Reiss’ (1991) expectancy theory to identify cause and effect relationships between previous conditioning events interested parties had experienced (i.e. sensitivities) and perceived risks related to the reintroduction (i.e. expectancies). We found respondents drew parallels to previous events including the red wolf reintroduction to North Carolina, other wildlife reintroductions in Arkansas, gray wolf (Canis lupus) reintroductions in Yellowstone National Park, and conflicts with other wildlife in Arkansas, where distrust for wildlife agencies underpinned these experiences. Based on our findings, we recommend agencies preemptively build trust and practice clear and frequent communication among interested parties when reintroductions are being considered.