Forest Ecosystem Management Research Articles

Tropical dry forests, water, biodiversity and the challenges of climate change in Nicaragua.

The Tropical Dry Forests of Nicaragua located mainly in the Pacific and Central-North zones play an essential role in maintaining resources such as water and the special biodiversity of this vulnerable ecosystem now under pressure from land-use changes and climate change These resources are essential to the well-being of the population as the main aquifers of the country are located in this area along with ecosystem services of this now heavily fragmented forest ecosystem. The ongoing influence of climate change along with land-use changes have caused the growth of arid zones in all of Central America. These on-going land use changes are lowering the resilience to the present and future climate change. Individual efforts to sustainable management of the forests are mentioned but it is nonetheless urgent to introduce wider and more intensive sustainable forestry and watershed management under a well-planned strategy based on findings of scientific research. The importance of the interrelationship between water and forests in the management of sustainable forest ecosystems will be stressed.

Predicting tree survival in agroforestry systems using machine learning classification algorithms

This article discusses the application of machine learning algorithms to predict the survival of trees in agroforestry systems. Forests play a key role in maintaining ecological balance and biodiversity, but their survival is subject to many threats, including climate change, anthropogenic impacts, diseases and pests. The study used a dataset containing data on various factors affecting the survival of trees, such as the content of phenols, the presence of arbuscular mycorrhizal fungi (AMF), lignin and non- structural carbohydrates (NSC). The classification model was built using the C4.5 decision tree algorithm, which demonstrated high accuracy (86.02%) in predicting the survival of trees. Correlation analysis revealed that phenols and AMF are the most significant factors determining the survival of trees. These results highlight the importance of biochemical and symbiotic factors for tree health. The article also discusses the importance of various factors and suggests directions for future research aimed at improving the management of forest ecosystems in agroforestry systems. The use of machine learning methods allows not only to improve the accuracy of forecasting, but also to develop more effective strategies for the conservation and sustainable management of forests.

FOREST LITTER PRODUCTION VARIES WITH SEASON AND ELEVATION GRADIENT IN CHIAPAS, MEXICO

<p><strong>Background.</strong> Forest litterfall is a fundamental process of ecosystem nutrient cycling, also, it is a source of energy for the development and propagation of wildfire. Understanding the temporal dynamics of litter production and storage is critical for sustainable management and conservation of forest ecosystems. <strong>Objective. </strong>To quantify<strong> </strong>the monthly production and storage of forest litter in an elevation gradient. <strong>Methodology.</strong> We selected forest sites at three elevations: 670, 775, and 1010 masl, corresponding to pine, oak, and tropical lowland forest ecosystems in Nambiyugua hill, Chiapas, Mexico. Sixteen sampling sites with a radius of 11.28 m were established for tree measurements, and 48 litter traps of 0.50 m<sup>2 </sup>were installed to collect monthly litterfall for a year. To sample ground litter eight 30 by 30 cm<sup>2</sup> quadrats were used in each site. The fallen woody material was measured with the planar intersection method. Litter samples were oven-dried at 60 °C for 72 h and separated into leaves and other plant parts. One-way ANOVA was used to test the significant differences between forests.<strong> Results.</strong> The highest total loads of litter and fallen woody material were obtained in the pine forests of upper elevation with 29.01 t ha<sup>-1</sup>. The highest litter production was obtained in January and April, with a mean of 1.34 ± 0.19 and 0.74 ± 0.13 t ha<sup>-1</sup> respectively in pine forests. In the oak forest, the highest production occurred in March, with 1.08 ± 0.25 t ha<sup>-1</sup>; while the lowland forest reached the highest production in January with 0.85 ± 0.26 t ha<sup>-1</sup>, with a decreasing trend in June. <strong>Implications.</strong> Understanding the seasonal variability in litter production and forest fuel loads is crucial for forest productivity, carbon sequestration, and wildfire prevention <strong>Conclusions.</strong> The production of forest fuels was different among the ecosystems representing the elevation gradients. The highest monthly production of litter was registered during the January-May period for the pine and oak ecosystems but in November - January in tropical lowland forests.</p>

Tight relationships between leaf and topsoil stoichiometries after 42 years of forest conversion from old-growth forests to Chinese fir plantations

Soil C:N:P stoichiometry can regulate plant survival and reflect soil fertility and nutrient utilization. Despite the widespread conversion of old-growth forests to plantations or secondary forests, there is little knowledge about how these conversions affect the relation between leaf and soil stoichiometries. We examined the topography, leaf, and soil stoichiometries of 75 plots (20 m × 20 m) across Chinese fir plantations, secondary forests, and old-growth forests in subtropical China. We found that: (1) There were significant differences in leaf carbon, nitrogen, phosphorus, and their stoichiometry ratios among different stand types (2) stand type significantly affected soil SOC, TP, C:N, C:P, and N:P, except TN and (3) the explanation percentage of leaf stoichiometry on soil stoichiometry doubled with the conversion of old-growth forest to Chinese fir plantation, whereas it was twofold decreased with the conversion of old-growth forest to secondary forest. The explanation percentage of topography on soil stoichiometry decreased onefold at a minimum with the conversion of the old-growth forest to the Chinese fir plantation or the secondary forest. Our results show the shortages of soil nutrients from transforming old-growth forests into plantations or secondary forests and indicate the urgent need to preserve the remaining old-growth forests and increase stand ages by reducing forest disturbances. Therefore, determining the optimal stand type and slope location can effectively promote the accumulation of carbon, nitrogen, and phosphorus nutrients in the topsoil, which is essential for improving the planning and implementation of appropriate forest restoration and ecosystem management strategies.

Diversity and ecological dynamics of ground and understory arachnid spiders from a lowland tropical forest in Sumber Pawon, Kediri, East Java

Spiders have significantly contributed to the dynamics of terrestrial ecosystems and play an essential role as appropriate bio-indicators to monitor habitat changes. We aim to determine the composition and local scale diversity of spiders in the understory and ground layers and to determine habitat preferences regarding the distribution of spiders in the interior forests and riparian forests. Sampling was conducted at a protected forest area in Sumber Pawon Kediri, covering an area of 12.45 Ha during the wet season (January-March). The study’s results found 340 individuals consisting of 15 families and 63 species. Family Araneidae and species Hamadruas superba are the most common taxa groups in the interior forests, while Hippasa holmerae are in riparian forests. More individuals and species are found understorey shrubs in forest interiors. Soil temperature, relative humidity, and litter thickness positively correlate with spider abundance. Resource partitioning observation showed that leaf litter and herbaceous plants contain more potential prey for spiders. Forest habitat management programs must consider the spatial variation of spiders between strata, as well as the response of the spiders to the seasons. A better understanding of spider ecological dynamics will support the sustainable management of forest ecosystems.

Determination of Health Index Classification and Management Sustainable Mangrove Ecosystems Using a Combination of Fuzzy and ISM Methods

The area of mangrove forests in Indonesia in 2021, according to the Ministry of Environment and Forestry, is around 3,364,080 Ha; this amount is equivalent to 23% of the world’s mangrove ecosystem, which is from a total of 16,530,000 Ha (FAO, 2005). Information on the condition of mangrove ecosystems is important to know whether or not an area is good. Studies related to the condition of mangrove ecosystems based on environmental quality and mangrove health index to determine the environmental quality and mangrove health are needed for ecosystem management in the future. This article describes the health parameters of mangrove ecosystems that will be analyzed with the help of a combination of decision support software such as fuzzy and ISM so that priority mangrove ecosystem locations can be determined, mangrove health index values to determine the health status of mangrove ecosystems and determine alternative sustainable mangrove ecosystem management policies that will be applied to the object of study. In addition, the study also discusses the concept of determining standard criteria for the level of damage to mangrove ecosystems and determining the status of mangrove ecosystems. Based on fuzzy logic, data analysis shows that the output of the Mangrove Health Index can be determined with 3 variables and 27 rules, with key factors in Mangrove Density, Canopy Cover and Number of saplings. The results of ISM show that management institutions that must be actively involved in supporting the success of sustainable mangrove forest ecosystem management in Batam City are KLHK, DLHK Riau Islands Province, and BPDAS Sei Jang Duriangkang. Proper handling of constraints and management institutions that are actively involved in mangrove forest ecosystem management will ultimately encourage budget effectiveness and efficiency to meet the main goal, namely sustainable mangrove forest ecosystem management in Batam City.

Quantifying patch size distributions of forest disturbances in protected areas across the European Alps

AbstractAimNatural disturbances are key drivers of forest ecosystem dynamics and are highly sensitive to global change. Despite their importance, central disturbance characteristics remain unknown for many forests worldwide. Here, we quantified an important component of the forest disturbance regime—the distribution of patch sizes—in strictly protected areas by asking: (i) How are patch sizes of naturally occurring disturbances distributed across the Alps and how can they best be quantified? (ii) Are patch size distributions stochastic or can they be explained by environmental drivers? (iii) What are the return periods of extreme disturbance events?LocationEuropean Alps.MethodsWe analysed satellite‐based disturbance maps for the period 1986–2020 across a network of 12 strictly protected areas, modelling patch sizes of all observed disturbance patches as well as of annual extreme events. We tested the influence of temperature, precipitation, topographic complexity and forest type on patch size distributions.ResultsDisturbance patch sizes across the Alps (median 0.36 ha, 5th percentile 0.18 ha and 95th percentile 1.71 ha) as well as their annual extremes (0.72 ha, 0.18–7.11 ha) are best described by a Fréchet distribution. The size of annual extreme events significantly increased with intra‐annual temperature amplitude (+0.98 ha with a one standard deviation increase) and the share of evergreen trees (+0.63 ha). On average, disturbance patches of 5.5 ha (95% credible interval 2.6–17.5 ha) occur once every 30 years, whereas patches of 2.6 ha (1.2–7.0 ha) occur once every 10 years.Main ConclusionsDisturbances caused by natural agents are generally small and stochastic across the Alps. Extreme events are driven by climate, suggesting sensitivity of disturbance patch sizes to climate change. Our results provide a baseline for monitoring climate‐induced changes in forest disturbance regimes, and provide important information for the management and conservation of forest ecosystems.

Spatial Distribution and Determinants of Aboveground Biomass in a Subalpine Coniferous Forest in Southwestern China

Aboveground biomass (AGB) is the most dynamic carbon pool in forest ecosystems and is sensitive to biotic and abiotic factors. Previous studies on AGB have mostly focused on tropical and temperate forests, while studies on AGB and its determinants in subalpine coniferous forests are lacking and the mechanisms are not yet clear. Here, we systematically investigated all woody plants in 630 subplots (20 m × 20 m) in the Wanglang Plot (25.2 ha) to explore the spatial distribution of AGB and the effects of topography, soil, and stand structure on AGB. The results showed that AGB varied remarkably among different subplots with an average of 184.42 Mg/ha. AGB increased significantly with aspect, soil organic matter, maximum DBH, and important value of spruce–fir, while it decreased significantly with slope, total phosphorus, and stem density. Stand structure exerted greater influences than topography and soil factors, and especially maximum DBH determines the variation of AGB. Our results are of great significance to accurately estimate and predict the productivity of this forest type, and can provide insights into the diversity maintenance of subalpine coniferous forests as well as the conservation and management of forest ecosystems.

Soil water infiltration characteristics of reforested areas in the paleo-periglacial eastern Liaoning mountainous regions, China

Plantation forests (PF) and natural secondary forests (NSF) are the primary reforestation approaches. The establishment of PF can affect forest hydrological processes by changing soil structure. To date, few studies have focused on these changes and the effects on hydrological processes for the paleo-periglacial landform. To reveal reforestation approaches effects on water infiltration, including soil water infiltration capacity, retention capacity, and waterflow path pattern, we conducted field dye-tracer investigations with rainfall and laboratory infiltration experiments for the paleo-periglacial landform of eastern Liaoning mountains, China. The results showed that (1) Soil physical properties (including total porosity (TP), capillary porosity (CP), non-capillary porosity (NCP), initial soil water content (IWC), field water capacity (FWC)) and root abundance (RA) decreased with soil depth in both PF and NSF, while the soil bulk density (BD) and distribution of gravel content showed opposite changes. (2) Establishment of PF reduced the infiltration capacity and water retention capacity in the 0–20 cm layer, but enhanced the water retention capacity in 20–30 cm layer. Low IWC was conducive to increase soil water content (SWC) after infiltration. (3) Infiltration capacity parameters (including saturated hydraulic conductivity (Ks), SWC, difference between SWC and IWC (SWC–IWC), dye coverage ratio (DC)) were significantly correlated with BD, TP, CP, NCP, FWC, and fine roots RA (P < 0.05). Better connectivity gravels were more conducive to water infiltration. (4) Preferential flow was the main infiltration type, but with different waterflow paths pattern, with the 'funnel', 'finger' shape for PF, NSF, respectively. Increasing infiltration could increase flow path connectivity. Our findings show that soil physical properties, roots, and gravel occurrence affected soil infiltration, and different reforestation approaches had varying impacts on soil infiltration, water redistribution, transportation, and storage of surface and groundwater, improving the understanding of ecohydrological processes and effects of water resources management in forest ecosystems of paleo-periglacial landform.

Heavy browsing pressure by moose (Alces alces) can interfere with the objectives of ecosystem-based forest management

Forest management can enhance the ecosystem services forests provide, but it can also alter the capacity of forests to provide those services in the future. Ecosystem-based management has been widely implemented to mitigate the deterioration of forest ecosystems by reducing dissimilarities between managed and natural forests. Ecosystem-based management objectives generally aim to maintain community composition, stand structure, ecosystem functions and services. Heavy browsing pressure by ungulates at densities unrepresentative of past abundance could interfere with these objectives by chronically and selectively browsing tree regeneration following logging.Using a browsing exclusion experiment, we investigated how the effects of different moose browsing pressures on tree regeneration could interfere with ecosystem management objectives in boreal forests of Quebec, Canada. Management objectives in this region include, among others, reaching targeted coniferous trees densities for commercial harvest, favouring the conservation of birches (Betula spp.) to maintain soil quality and conserving fruit-bearing trees due to their ecological significance for biodiversity. We used path analyses to differentiate direct and indirect effects of moose on seedling density and mixed models to investigate how browsing affected sapling recruitment and whether resulting densities are compatible with ecosystem management objectives.By directly reducing the overall sapling density, moose browsing indirectly increased seedlings densities of all deciduous species. This indirect effect increased with browsing pressure and favoured raspberry cover, which was positively or negatively linked to seedling density, depending on tree species. Moderate and heavier browsing pressures reduced coniferous sapling density below the ecosystem management target. Moose suppressed birch saplings so that the minimal target of 50 birches ha−1 was not met under heavier browsing pressure. Sapling density of fruit-bearing trees was low under all browsing pressures when compared to exclosures.Policy implicationsHeavy moose browsing is preventing the achievement of ecosystem management objectives in our study area. Positive indirect effects on seedling densities suggest that reducing moose density could allow released seedlings to replenish the sapling layer, but we discuss why this would not guarantee reaching ecosystem management objectives. To help forest managers evaluate and respond to challenges posed by high ungulate densities, we suggest incorporating browsing inventories in national forest surveys to monitor this chronic disturbance and modulate decisions for forest ecosystem management.

Elucidating factors driving post-fire vegetation recovery in the Mediterranean forests using Landsat spectral metrics

Wildfires represent one of the primary disturbance agents in the Mediterranean, significantly affecting the ecological integrity of forests. Therefore, understanding the spatial patterns of post-fire vegetation recovery is crucial to improving forest restoration planning and assessing the regeneration capacity of different forest stands that have been impacted by wildfires. In this study, we analysed post-fire vegetation recovery rates within the context of fire severity, pre-fire vegetation, and post-fire climate conditions, for different Mediterranean forest classes, namely, Mediterranean pine, holm, deciduous oak forests, sclerophyllous vegetation, and thermophilous shrublands. Basilicata, in Italy, was chosen as a study area, as it represents a wide range of forests.The Relative Recovery Indicator (RRI) was derived from Normalized Burn Ratio (NBR) patterns extracted from 30-meter Landsat time series for different wildfires that occurred during the 2004–2016 within Google Earth Engine (GEE) environment. A Linear Mixed Model (LMM) was used to test the effect of the different variables on the RRI. Results showed a general decrease in recovery rate within five-years post-fire for each forest cover class, which is mainly related to pre- and post-fire conditions. Pre-fire vegetation conditions significantly influenced post-fire vegetation recovery, especially in sclerophyllous and deciduous oak forests. Post-fire climate conditions (e.g., temperature) were also important predictors of vegetation recovery explaining the variation in post-fire RRI patterns. The proposed method could provide new insights into the restoration and management of forest ecosystems in the Mediterranean.

A dataset of bird checklist and community characteristics during breeding and wintering seasons in typical forest ecosystems of Dinghushan (2015–2018)

Bird diversity and its community structure are important indicators for the long-term monitoring of biodiversity in ecosystems. Three typical forest vegetation types have been well preserved in Dinghushan National Nature Reserve, including the monsoon evergreen broad-leaved forest, the mixed Pinus massoniana/broad-leaved forest and the Pinus massoniana coniferous forest. In particularly, the monsoon evergreen broad-leaved forest has a conservation history of more than 400 years without any human disturbance. The dataset consists of organized data on the long-term monitoring of bird communities during breeding and wintering seasons from 2015 to 2018 in all three forest types. Field surveys recorded information such as bird species, number, time, distance, ground height, habitat type, activity substrate and behavior. Moreover, we carried out various data analyses of diversity index, evenness index, dominance index, similarity coefficient of bird community and occurrence frequency, individual number, as well as average density of bird species in different survey periods. The dataset includes a total of 89 species from 9 orders and 35 families. This dataset provides valuable information for future studies on bird communities, and for better understanding inter-species interaction between multiple groups of plants and animals. It is further expected to support the protection and management of forest ecosystems in this region.

Assessing the environmental destruction in forest ecosystems using landscape metrics and spatial analysis

Forest degradation is a serious environmental issue that has significant implications for ecological stability, biodiversity, and human well-being. Identifying the extent and severity of forest degradation is crucial for effective management and conservation of forest ecosystems. The objective of this study was to assess the ecological vulnerability of the forest in the Dadabad region using spatial analysis and landscape metrics. The land cover map of the area was divided into 13 sub-basins to quantify landscape metrics, and the severity of human activities, degradation level, and ecological vulnerability were calculated for each sub-basin. Each sub-basin was evaluated as a single landscape to determine the extent of degradation, and landscape zoning was performed based on the degradation coefficients. The study found that sub-basins 2 and 4 had the highest levels of degradation, while sub-basins 3, 7, 8, 11, and 12 were the least degraded. Over half of the Dadabad region, 37.8% for protection and 32.25% for rehabilitation, was recommended for conservation planning. The research highlights the importance of using spatial analysis of landscape metrics to assist managers and planners in protecting and conserving natural areas.

Natural regeneration in tropical forests along a disturbance gradient in South-East Cameroon

The dynamics of tropical forests are highly dependent on the forest understorey. Understanding its diversity and composition is essential to ensure sustainable management of forest ecosystems. In this study, following a gradient of human disturbance, we analysed the density, diversity and floristic composition of the forest understorey in three land use types of south-eastern Cameroon: a protected area, a selective logging concession and community forests. Vegetation was inventoried in thirty-three permanent one-hectare plots. Woody individuals (tree, shrub, liana) were classified in four strata depending on their diameter: seedling (dbh < 1 cm), sapling (1–9.9 cm), small trees (10–29.9 cm), large tree (≥30 cm). A total of 4,159 individuals (dbh < 10 cm) belonging to 418 species and 232 genera were recorded. They mainly represent tree species (65%) and shade tolerant plants (77%), with diaspores disseminated by animals (74%). Life forms and modes of dissemination were significantly different between land use types. Abundance, species richness and diversity of juveniles varied significantly between strata and land use types: they were globally the highest in plots that have been logged less than five years before inventory. In terms of species composition, the different land use types were not clearly separated, indicating some resilience to disturbance. A low similarity between strata was observed. In all types, most canopy species are light demanding and cannot regenerate in the understorey. This indicates a natural evolution of the forest stands in the absence of silviculture. The presence of species that currently dominate the canopy of these forests will be gradually reduced without human intervention.

Synergistic management of forest and reservoir infrastructure improves multistakeholders’ benefits across the forest-water-energy-food nexus

Forest management can influence multistakeholders' benefits across the forest-water-energy-food nexus at the watershed scale. However, bringing synergistic gains for multiple stakeholders is still a challenge for regional sustainable management. We took the Changhuajiang basin in China's Hainan Island as a case to present the impacts of synergistic management for upstream forest and reservoir optimization on the benefits of downstream hydropower enterprise and different farmers. By multimodel ensembles and scenario analysis, we quantified the relationships among upstream forest ecosystem management (rubber-intercropped), reservoir, water flow and downstream stakeholders' benefits (i.e., hydropower generation for the energy company, and available irrigation water for two downstream sites' farmers). We also adopted the genetic optimization algorithm to obtain the optimal reservoir infrastructure operation rule for the benefit improvement of multiple stakeholders. We found that rubber-intercropped management significantly increased reservoir inflow in the dry seasons (5%–170%) and reduced it in the rainy seasons (0.5%–7%). The irrigation water availability for downstream farmers in the Gao Canal and downstream irrigation areas correspondingly increased by 7% and 24.3% on average, respectively, with a slight change in hydropower production. Further, we found that water regulation by reservoir optimization operation could enhance the irrigation water supply (36.6–92% and 0–100% in Gao Canal and downstream irrigation areas, respectively) and hydropower generation (14.8–28.4%). This study indicates that the effect of upstream forest management on downstream multistakeholders' benefits could be strengthened by reservoir water flow regulation across the forest-water-energy-food nexus, and demonstrates the key role of infrastructure in regulating ecosystem service flow for strengthening the benefits of multistakeholders in the context of ecosystem management.

A General Rule-Based Framework for Generating Alternatives for Forest Ecosystem Management Decision Support Systems

Linear programming formulations of forest ecosystem management (FEM) problems proposed in the 1960s have been adapted and improved upon over the years. Generating management alternatives for forest planning is a key step in building these models. Global forests are diverse, and a variety of models have been developed to simulate management alternatives. This paper describes iGen, a forest prescription generator that employs a rule-based system (AI-RBS), an AI technique that is often used for expert systems. iGen was designed with the goal of being able to generate management alternatives for virtually any FEM problem. The prescription generator is not designed for, adapted to, focused on—and ideally not limited to—any specific region, landscape, forest condition, projection method, or yield function. Instead, it aims to maximize generality, enabling it to address a broad range of FEM problems. The goal is that practitioners and researchers who do not have and do not want to develop their own alternative generator can use iGen as a prescription generator for their problem instances. For those who choose to develop their own alternative generators, we hope that the concepts and algorithms we propose in this paper will be useful in designing their own systems. iGen’s flexibility can be attributed to three key features. First, users can define the state variable vector for management units according to the available data, models (production functions), and objectives of their problem instance. Second, users also define the types of interventions that can be applied to each type of management unit and create a rule base describing the conditions under which each intervention can be applied. Finally, users specify the equations of motion that determine how the state vector for each management unit will be updated over time, depending on which, if any, interventions are applied. Other than this basic structure, virtually everything in an iGen problem instance is user-defined. iGen uses these key elements to simulate all possible management prescriptions for each management unit and stores the resulting information in a database that is structured to efficiently store the output data from these simulations and to facilitate the generation of optimization models for ultimately determining the Pareto frontier for a given FEM problem. This article introduces iGen, illustrating its concepts, structure, and algorithms through two FEM example problems with contrasting forest management practices: natural regeneration with shelterwood harvests and plantation/coppice. For data and iGen source programs, visit github.com/SilvanaNobre/iGenPaper.

Effects of Canopy Damage and Litterfall Input on CO2-Fixing Bacterial Communities

Extreme weather events often cause canopy disturbance and litter deposition. To study the CO2-fixing bacterial response to forest damage, we simulated the canopy damage caused by extreme weather with four different treatments: control (CN), canopy trimming + removal of branches and leaves debris (TR), canopy trimming + retaining of branches and leaves debris (TD), and undamaged + transplantation of branches and leaves debris (UD). We used the cbbL gene, which encodes ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO), for Miseq sequencing to analyze the dynamics of community composition of soil CO2-fixing bacteria for five consecutive years after canopy damage. Double treatments of canopy damage and litterfall inputs (TD) facilitate forest restoration better than single treatments (TR or UD). Most soil CO2-fixing bacteria are facultative autotrophic bacteria, and Nitrosospira, Streptomyces, and Saccharomonospora are the main carbon-fixing microorganisms, which have significant differences during the restoration of damaged forest canopy. The forest ecosystem restoration after canopy damage lasted 4–5 years. Rainfall and pH showed a significant negative correlation with most soil CO2-fixing bacteria communities. This study provides a theoretical basis for improving the carbon sequestration capacity of forest soil CO2-fixing bacteria after extreme weather and also provides guidance for forest ecosystem management.

Forest Phenology under Differing Topographic Conditions: A Case Study of Changbai Mountain in Northeast China

Forest phenology is sensitive to climate change, and its responses affect many land surface processes, resulting in a feedback effect on climate change. Human activities have been the main driver of climate change’s long-term shifts in temperature and weather patterns. Forest phenology, understood as the timing of the annual cycles of plants, is extremely sensitive to changes in climate. Quantifying the responses of temperate forest phenology under an elevational range of topographic conditions that mimic climate change is essential for making effective adaptive forest ecosystem management decisions. Our study utilized the Google Earth Engine (GEE), gap filling, and the Savitzky–Golay (GF-SG) algorithm to develop a long-time series spatio-temporal remote sensing data fusion. The forest phenology characteristics on the north slope of Changbai Mountain were extracted and analyzed annually from 2013 to 2022. Our study found that the average start of the growing season (SOS) on the north slope of Changbai Mountain occurred between the 120th–150th day during the study period. The end of the growing season (EOS) occurred between the 270th–300th day, and the length of the growing season (LOS) ranged from the 110th–190th day. A transect from the northeast to southwest of the study area for a 10-year study period found that SOS was delayed by 39 d, the EOS advanced by 32 d, and the LOS was gradually shortened by 63 d. The forest phenology on the north slope of Changbai Mountain showed significant topographic differentiations. With an increase of 100 m in altitude, the mean SOS was delayed by 1.71 d (R2 = 0.93, p &lt; 0.01). There were no obvious trends in EOS variation within the study area altitude gradient. LOS decreased by 1.23 d for each 100 m increase in elevation (R2 = 0.90, p &lt; 0.01). Forests on steep slopes had an earlier SOS, a later EOS, and a longer LOS than forests on gentle slopes. For each degree increase in slope, SOS advanced by 0.12 d (R2 = 0.53, p = 0.04), EOS was delayed by 0.18 d (R2 = 0.82, p = 0.002), and the LOS increased by 0.28 d (R2 = 0.78, p = 0.004). The slope aspect had effects on the EOS and the LOS but had no effect on the SOS. The forest EOS of the south aspect was 3.15 d later than that of the north aspect, and the LOS was 6.47 d longer. Over the 10-year study period, the phenology differences between the north and south aspects showed that the LOS difference decreased by 0.85 d, the SOS difference decreased by 0.34 d, and the EOS difference decreased by 0.53 d per year. Our study illustrates the significance of the coupling mechanism between mountain topography and forest phenology, which will assist our future understanding of the response of mountain forest phenology to climate change, and provide a scientific basis for further research on temperate forest phenology.

Integrating wildfire resistance and environmental concerns into a sustainable forest ecosystem management approach

This research aims at presenting landscape management planning methods to help stakeholders select forest ecosystem management plans that may address concerns with wildfire risk and with the environmental impacts of clearcuts. Specifically, we develop mixed integer programming models for spatial optimization that incorporate a wildfire resistance index as well as constraints on the size of clearcut openings. The former is used to enforce a minimum level of resistance to wildfire while the latter limits the size of openings, in each period of the planning horizon. Timber volume even flow is another concern that is also taken into account. This research is applied to the Zonas de Intervenção Florestal (ZIF) de Paiva and de Entre-Douro e Sousa (ZIF_VS) which are located in northwestern Portugal.

Ecological Stoichiometry and Stock Distribution of C, N, and P in Three Forest Types in a Karst Region of China.

Ecological stoichiometry plays important roles in understanding the nutrient constraints on tree growth and development, as well in maintaining ecosystem services in forests, yet the characteristics of carbon:nitrogen:phosphorous (C:N:P) stoichiometry in forests under karst environment have not been sufficiently evaluated. In this study, concentration, distribution, stocks of Nitrogen (N) and Phosphorous (P), and ecological stoichiometry were studied in three common forest types: Masson pine natural forests (MPNF), Masson pine plantation forests (MPPF), and Slash pine plantation forests (SPPF) in a karst region of southwestern China. Results showed that N concentrations were higher in overstory than in understory and litter in the studied forests. However, P concentration was relatively low in overstory component of the forested ecosystems. Meanwhile, the N and P concentrations were higher in SPPF in the stem and litter, while these contents were higher in MPPF and MPNP in the overstory and understory. The N and P stocks ranged from 5.7-6.2 t ha-1, and 0.5-0.6 t ha-1 in the examined forests. The ecological stoichiometry of C:N:P in the three forest types was similar in litter (46-49:2:1), and relatively steady in soil (250-320:13-16:1) and tree leaf (100-200:14-20:1). Soil P status was the primary limiting factor in affecting tree growth in MPPF and SPPF (N:P ratio > 16), while both N and P conditions were the main restrictive factors in MPNP (N:P ratio = 15) in the study area. Our study provides scientific references and useful datasets of C:N:P stoichiometry for sustainable management of forest ecosystems in karst regions.