Sustainable Management Of Forest Ecosystems Research Articles

Climate-smart forestry: an AI-enabled sustainable forest management solution for climate change adaptation and mitigation

AbstractClimate change is the most severe ecological challenge faced by the world today. Forests, the dominant component of terrestrial ecosystems, play a critical role in mitigating climate change due to their powerful carbon sequestration capabilities. Meanwhile, climate change has also become a major factor affecting the sustainable management of forest ecosystems. Climate-Smart Forestry (CSF) is an emerging concept in sustainable forest management. By utilizing advanced technologies, such as information technology and artificial intelligence, CSF aims to develop innovative and proactive forest management methods and decision-making systems to address the challenges of climate change. CSF aims to enhance forest ecosystem resilience (i.e., maintain a condition where, even when the state of the ecosystem changes, the ecosystem functions do not deteriorate) through climate change adaptation, improve the mitigation capabilities of forest ecosystems to climate change, maintain high, stable, and sustainable forest productivity and ecosystem services, and ultimately achieve harmonious development between humans and nature. This concept paper: (1) discusses the emergence and development of CSF, which integrates Ecological Forestry, Carbon Forestry, and Smart Forestry, and proposes the concept of CSF; (2) analyzes the goals of CSF in improving forest ecosystem stability, enhancing forest ecosystem carbon sequestration capacity, and advocating the application and development of new technologies in CSF, including artificial intelligence, robotics, Light Detection and Ranging, and forest digital twin; (3) presents the latest practices of CSF based on prior research on forest structure and function using new generation information technologies at Qingyuan Forest, China. From these practices and reflections, we suggested the development direction of CSF, including the key research topics and technological advancement.

A growth-effective age-based periodic site-index for the estimation of dynamic forest site productivity under environmental changes

Key messageA novel periodic site index is introduced for the quantification of dynamic forest site productivity. The measure is age-independent, sensitive to environmental changes and efficient for the estimation and prediction of stand height and stand volume increment.ContextAccurate and up-to-date prediction of site productivity is crucial for the sustainable management of forest ecosystems, especially under environmental changes.AimsThe aim of this study was to introduce a novel concept: a periodic site index based on growth-effective age for the quantification of dynamic forest site productivity.MethodsThe growth-effective age based periodic site index is estimated from repeated or multi-temporal measurements of stand dominant height. Furthermore, a recursive procedure to update the underlying site index model is presented by using repeated measurements of stand dominant height. The database used in this study comprised repeated measurements of 945 Norway spruce (Picea abies L.) experimental plots at 508 different locations in Southwest Germany.ResultsThe evaluation shows that periodic site index is statistically superior to the conventional site index, based on chronological stand age, for estimating stand height and stand volume increment. The analysis of temporal differences between growth-effective stand age and chronological stand age and between periodic site index and conventional site index in the period 1900 to 2020 reveals trends referring to stand age and site productivity, which corroborate earlier regional studies on forest growth trends due to environmental changes.ConclusionsThe periodic site index is a better indicator for site productivity than conventional site index. Under conditions of environmental changes, conventional site index is biased, whereas the growth-effective age based site index provides an unbiased estimate of stand height development. With the more widespread application of remote sensing techniques, such as airborne laser scanning, the availability of multi-temporal stand height data will increase in the near future. The novel concept provides an adaptive modeling approach perfectly suited to these data for an improved estimation and prediction of forest site productivity under environmental changes and can straightforwardly be applied also to uneven-aged and multi-species stands.

Scale-dependent effects of vegetation attributes and soil fertility on productivity in two temperate forests in Northeast China

Forests are rich in biodiversity and high in productivity, and understanding the relationship between biodiversity and productivity is critical to the sustainable management of forest ecosystems. Although biodiversity and other factors contribute to forest productivity to varying degrees, it is unclear whether spatial scale (or plot size) influences this relationship. In this study, we analyzed the impacts of biodiversity, trait composition, structural attributes, and soil fertility on forest productivity at three scales in two temperate old-growth forests. We found that structural attributes, including basal area and stand density, were positively correlated with productivity and were consistently the strongest drivers of productivity changes in both forest types. Trait composition had a weak direct positive correlation with productivity. Soil nitrogen had positive effects on productivity, and soil moisture content had negative effects, both of which increased with increasing plot size. Different results for the effect of biodiversity on productivity were found between the two forests. In the mixed broadleaved-Korean pine forest, diversity correlated positively with productivity, and the strength of the relationship increased with increasing plot size. In contrast, in the spruce-fir valley forest, diversity had a direct positive correlation with productivity at 10 m × 10 m, no significant effect at 20 m × 20 m, and a negative correlation at 30 m × 30 m. Our results suggest that the contribution of vegetation attributes and soil fertility to forest productivity varies with scale. Despite the fact that both the niche complementarity hypothesis and the mass ratio hypothesis act simultaneously in forests, they have limited effects on productivity. Stand structural attributes play a key role in elucidating the biodiversity-productivity relationships, and they may serve as a more significant regulator of forest productivity than diversity. At the same time, the role of soil fertility in regulating productivity cannot be ignored.

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

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

Multi-Agent Reinforcement Learning for Stand Structure Collaborative Optimization of Pinus yunnanensis Secondary Forests

This study aims to investigate the potential and advantages of multi-agent reinforcement learning (MARL) in forest management, offering innovative insights and methodologies for achieving sustainable management of forest ecosystems. Focusing on the Pinus yunnanensis secondary forests in Southwest China, we formulated the objective function and constraints based on both spatial and non-spatial structural indices of the forest stand structure (FSS). The value of the objective function (VOF) served as an indicator for assessing FSS. Leveraging the random selection method (RSM) to select harvested trees, we propose the replanting foreground index (RFI) to enhance replanting optimization. The decision-making processes involved in selection harvest optimization and replanting were modeled as actions within MARL. Through iterative trial-and-error and collaborative strategies, MARL optimized agent actions and collaboration to address the collaborative optimization problem of FSS. We conducted optimization experiments for selection felling and replanting across four circular sample plots, comparing MARL with traditional combinatorial optimization (TCO) and single-agent reinforcement learning (SARL). The findings illustrate the superior practical efficacy of MARL in collaborative optimization of FSS. Specifically, replanting optimization based on RFI outperformed the classical maximum Delaunay generator area method (MDGAM). Across different plots (P1, P2, P3, and P4), MARL consistently improved the maximum VOFs by 54.87%, 88.86%, 41.34%, and 22.55%, respectively, surpassing those of the TCO (38.81%, 70.04%, 41.23%, and 18.73%) and SARL (54.38%, 70.04%, 41.23%, and 18.73%) schemes. The RFI demonstrated superior performance in replanting optimization experiments, emphasizing the importance of considering neighboring trees’ influence on growth space and replanting potential. Following selective logging and replanting adjustments, the FSS of each sample site exhibited varying degrees of improvement. MARL consistently achieved maximum VOFs across different sites, underscoring its superior performance in collaborative optimization of logging and replanting within FSS. This study presents a novel approach to optimizing FSS, contributing to the sustainable management of Pinus yunnanensis secondary forests in southwestern China.

Impact of Deforestation on Water Quality in Cameroon

Purpose: The aim of the study was to analyze the impact of deforestation on water quality in Cameroon. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Deforestation in Cameroon significantly impacts water quality, as evidenced by increased sedimentation, higher pollutant levels, and elevated risks of waterborne diseases. Loss of forest cover reduces natural filtration capacities, leading to higher concentrations of contaminants in water sources. Alterations in hydrological patterns and changes in land use further exacerbate these issues, affecting water availability and aquatic habitats. Unique Contribution to Theory, Practice and Policy: Hydrological cycle theory, land use/land cover change (LU/LC) theory &amp; ecosystem services theory may be used to anchor future studies on impact of deforestation on water quality in Cameroon. Implement land-use planning measures that prioritize the conservation and sustainable management of forest ecosystems, including protected area designation, forest restoration initiatives, and sustainable forest management practices. Develop and enforce policies that incentivize forest conservation and sustainable land management practices, such as payment for ecosystem services schemes, land-use zoning regulations, and carbon offset programs.

Relationships between ecosystem services provided by forest ecosystems and human well-being

Current climate change trends significantly influenceing the structure and functioning of natural ecosystems, including forest ecosystems, which directly or indirectly affects human well-being. The present study consists in reviewing the specialized literature on the effects of the relationships between ecosystem services provided by forest ecosystems and human well-being, describing the following aspects: the definition of the concept of ecosystem services, their history, categories of ecosystem services and the relationship between them and human well-being. The concept of ecosystem services has become an important model of the link between forest ecosystem functioning and human well-being. Understanding this linkage is essential for a wide range of decision-making contexts for the sustainable management of forest ecosystems. We conclude that humanity’s dependence on nature for well-being and survival is complex.

Impacts of the Integrated Management of Invasive Weeds and Litter on Slope Hydrology in Eucalyptus Plantations in Central Yunnan, Southwest China

Background: The hydrological effects of invasive plant control in forestland have not been well studied in the past, and numerous scientific mysteries remain unsolved. The long-term suspension of the unsolved issues will unavoidably influence the sound growth and sustainable management of forest ecosystems. This study investigates the hydrological effects of controlling invasive weeds in forestland. The research aims to understand the impact of invasive weed control on soil and water loss. Methods: Conducted in Eucalyptus benthamii Maiden &amp; Cambage plantations in Central Yunnan, SW China, which are invaded by alien weed Ageratina adenophora (Spreng.) R. M. King &amp; H. Rob., four surface cover treatments were applied to study runoff and sediment yielding properties. The four surface cover treatments were weed harvesting and litter elimination (WH&amp;LE), weed harvesting and litter retention (WH&amp;LR), litter burning and weed renewal (LB&amp;WR), and weed retention and litter retention (WR&amp;LR). Essentially, WH&amp;LE and LB&amp;WR served as integrated management approaches for invasive weeds and litter, WH&amp;LR was an independent weed control measure, and WR&amp;LR served as a research control. Results: Runoff was significantly higher in the LB&amp;WR plots (3.03 mm) compared to the WR&amp;LR plots (1.48 mm) (p &lt; 0.05). The WH&amp;LE plots had higher runoff (2.39 mm) than the WR&amp;LR plots (not statistically significant), while the WH&amp;LR plots had less runoff (1.08 mm) than the WR&amp;LR plots (not significant). Sediment yield was lower in the WH&amp;LR plots (0.50 t/km2) than in the WR&amp;LR plots (0.52 t/km2) (not significant), but significantly higher in the WH&amp;LE plots (2.10 t/km2) and LB&amp;WR plots (1.57 t/km2) than in the WR&amp;LR plots (p &lt; 0.05). Conclusions: Managing invasive weeds independently reduces the risk of soil and water loss, but combined management with litter can exacerbate the issue. Invasive weed control and litter management should be performed separately in slope plantations. This study provides a scientific basis for soil and water conservation, restoration and rehabilitation of plantation ecosystems.

A thorough assessment of various forest management planning initiatives and development of improvement strategies towards an ecosystem-based planning

Management planning for forests in Turkey has undergone gradual evolution over the last century. Developing and implementing a comprehensive management planning framework present significant challenges. This paper evaluates the effectiveness of various forest management planning approaches implemented across the country over different time periods, with overarching planning principles. It formulates a robust planning framework and proposes improvements grounded in scientific advancements and international standards. The assessment indicated that the management plans were developed using reputable scientific methods and principles aimed at ensuring the sustainable management of forest resources with certain strengths and opportunities presented by SWOT analysis. All management plans shared a common planning concept primarily focused on maximizing wood production through the area-control harvest scheduling method (except for continuous cover forest, which employed the single tree selection method). Each management plan established its unique vision, targets, policies, objectives, and planning guidelines. Forest inventory data were gathered through a combination of ground surveys and remotely sensed data to characterize and stratify the landscape. A robust in-house management authority and governance system with appropriate technical capacity and guidelines were developed and implemented, fostering a sound common working culture and tools. However, some notable drawbacks were identified, including political pressure, biomass/carbon accounting, growth-yield modelling, economic analysis, limited characterization of the full range of ecosystem services, risk and uncertainty analysis, food security and, particularly, long-term sustainability and scenario analysis with the appropriate decision-making tools and methods. Despite a few strengths, these limitations may raise concerns about the far-sighted design and application, potentially jeopardizing the sustainable management of forest ecosystems. Proposed improvement strategies for an efficient forest ecosystem management planning system include characterization of ecosystem services, modelling their productivity, scenario analysis with a decision support system, stakeholder involvement, balancing utilization and conservation targets, conducting risk and uncertainty analysis and economic analysis of management actions.

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

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

Addressing Epistemic Injustice: Engaging Children as Environmental Communicators to Support the Long-Term Sustainability of Forest Ecosystems

Closure of a forest for biosecurity purposes led to the marginalisation and disconnection of Year 6 children from a local forest of significance to them in Aotearoa, New Zealand. The marginalisation of children’s voices and concomitantly of their knowledge, ideas, and values from environmental issues can be viewed as an example of epistemic injustice, which manifests widely in the environmental area, particularly in relation to marginalised groups. To counter this marginalisation and promote epistemic justice, we explored how the creative arts involving a child-driven environmental communication project could foster children’s sense of agency by supporting the protection of a local forest affected by a tree disease. We show that the creative arts could facilitate the children’s meaningful engagement in environmental issues in a learning environment that fostered child-centric approaches that enabled children to express their visions for sustainable futures in distinctly unique ways that were relevant to them. Furthermore, enabling the children to participate as environmental communicators re-established their relationship with their local forest and re-balanced the power structures that had led to the children’s sense of marginalisation. The insights on how this child-centred relational approach can promote epistemic justice and provide a meaningful contribution to the long-term sustainable management of forest ecosystems has implications for other marginalised groups.

Ectomycorrhizal necromass turnover is one‐third of biomass turnover in hemiboreal Pinus sylvestris forests

Societal Impact StatementEfficient mitigation of climate change requires predictive models of forest ecosystems as sinks for atmospheric carbon. Mycorrhizal fungi are drivers of soil carbon storage in boreal forests, yet they are typically excluded from ecosystem models, because of a lack of information about their growth and turnover. Closing this knowledge gap could help us better predict future responses to climate change and guide policy decisions for sustainable management of forest ecosystems. This study provides new estimates of the production and turnover of mycorrhizal mycelial biomass and necromass. This information can facilitate the integration of mycorrhizal fungi into new predictive models of boreal forest soils.Summary In boreal forests, turnover of biomass and necromass of ectomycorrhizal extraradical mycelia (ERM) are important for mediating long‐term carbon storage. However, ectomycorrhizal fungi are usually not considered in ecosystem models, because data for parameterization of ERM dynamics is lacking. Here, we estimated the production and turnover of ERM biomass and necromass across a hemiboreal Pinus sylvestris chronosequence aged 12 to 100 years. Biomass and necromass were quantified in sequentially harvested in‐growth bags, and incubated in the soil for 1–24 month, and Bayesian calibration of mathematical models was applied to arrive at parametric estimates of ERM production and turnover rates of biomass and necromass. Steady states were predicted to be nearly reached after 160 and 390 growing season days, respectively, for biomass and necromass. The related turnover rates varied with 95% credible intervals of 1.7–6.5 and 0.3–2.5 times yr−1, with mode values of 2.9 and 0.9 times yr−1, corresponding to mean residence times of 62 and 205 growing season days. Our results highlight that turnover of necromass is one‐third of biomass. This together with the variability in the estimates can be used to parameterize ecosystem models, to explicitly include ERM dynamics and its impact on mycorrhizal‐derived soil carbon accumulation in boreal forests.

Optimal Allocation of Water Reservoirs for Sustainable Wildfire Prevention Planning via AHP-TOPSIS and Forest Road Network Analysis

The sustainable management of forest ecosystems is directly linked to the management of forest fires. The increasing occurrence of wildfires has prompted the need for the establishment of infrastructure aimed at addressing them. The placement of anti-fire water reservoirs can address the lack of water intake points. This study introduces a decision support system (DSS) tailored for the optimal allocation of anti-fire water reservoirs in Mediterranean forest ecosystems, ensuring a reliable water supply for firefighting operations. The methodology integrates the analytical hierarchy process (AHP) and the technique of order of preference by similarity to ideal solutions (TOPSIS) methods, facilitating precise location determination through comprehensive criteria analysis. Additionally, the analysis of the forest road network is incorporated to optimize the placement of water reservoirs. In the forest complex of Taxiarchis, Chalkidiki, Greece, 100 potential reservoir sites were identified and prioritized based on factors such as fire risk, proximity to existing water sources, and coverage area using optimal pathways. The study’s findings demonstrate that by establishing 34 water reservoirs, firefighting forces can access a replenishment point within a 5-min travel time. The conclusions underscore the efficacy of this methodology as a valuable decision-making tool for sustainable wildfire prevention planning. This approach contributes to allocating resources judiciously, effectively mitigating the wildfire risk in Mediterranean forest ecosystems, and therefore promoting sustainability.

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.

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.

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.

Effect of environmental and spatial factors on the phylogenetic and functional diversity of the Mediterranean tree communities of Europe.

The tree flora of the Mediterranean Basin contains an outstanding taxonomic richness and a high proportion of endemic taxa. Contrary to other regions of the Mediterranean biome, a comprehensive phylogenetic analysis of the relationship between phylogenetic diversity, trait diversity and environmental factors in a spatial ecological context is lacking. We inferred the first calibrated phylogeny of 203 native tree species occurring in the European Mediterranean Basin based on 12 DNA regions. Using a set of four functional traits, we computed phylogenetic diversity for all 10,042 grid cells of 10 × 10 km spatial resolution to completely cover Mediterranean Europe. Then, we tested the spatial influence of environmental factors on tree diversity. Our results suggest that the nature of the relationship between traits and phylogeny varies among the different studied traits and according to the evolutionary distance considered. Phylogenetic diversity and functional diversity of European Mediterranean trees correlated strongly with species richness. High values of these diversity indices were located in the north of the study area, at high altitude, and minimum temperature of the coldest month. In contrast, the two phylogenetic indices that were not correlated with species richness (Mean Phylogenetic Distance, Phylogenetic Species Variability) were located in the south of the study area and were positively correlated with high altitude, soil organic carbon stock and sand soil texture. Our study provides support for the use of phylogenies in conservation biology to assess ecosystem functioning, and provides insights for the implementation of sustainable forest ecosystem management.

Altitudinal Gradients Modify the Ecological Stoichiometry and Enzyme Activities of Soil in a Natural Secondary Quercus spp. Forest of the Dabie Mountains

Understanding the vertical distribution and driving mechanisms behind soil carbon (C), nitrogen (N), and phosphorus (P) contents and enzyme activities along elevation gradients is of great significance for the healthy and sustainable management of forest ecosystems. For this study, the 0–20 cm soil-layer samples of different natural Quercus spp. secondary forests from eight altitude gradients (ranging from 250 to 950 m) were investigated to quantify their physicochemical properties, ecological stoichiometry characteristics, and enzyme activities. The results indicated that the soil nutrient content of natural secondary Quercus spp. forests in the Dabie Mountains was low, with average soil organic carbon (SOC) and total phosphorus (TP) contents of 19.86 ± 3.56 g·kg−1 and 0.68 ± 0.10 g·kg−1, respectively, which were 19.14% and 12.82% lower, respectively, than the Chinese average. In terms of vertical spatial distribution, the SOC, total nitrogen (TN), and TP contents of the soil at high altitudes (≥750 m) were greater than those at middle- and low-altitude areas and reached the maximum value at or near the top of the mountain (850–950 m). The stoichiometric attributes of the soil ecosystem fluctuated with the higher altitudes in vertical space; however, the fluctuation range was not significant. The C:N, N:P, and C:P ratios reached their maximum values at altitudes of 250, 750, and 850 m, respectively. However, the overall average value remained generally lower than the national average; thus, in forest management, attention should be paid to the supplementation of the soil with C and P. The activities of soil sucrase, urease, acid phosphatase, and catalase were interconnected across the overall space, and increased with altitude. The SOC, TP, and pH were the main factors that influenced the changes in soil enzyme activities.

Development and Testing of a New UWB Positioning Measurement Tool to Assist in Forest Surveys

Forest resource inventory is a significant part of the sustainable management of forest ecosystems. Finding methods to accurately estimate the diameter at breast height (DBH), tree height and tree position is a significant part of forest resource inventory. The traditional methods of forest resource inventory are expensive, difficult, laborious and time-consuming; the existing systems are not convenient to carry, resulting in low working efficiency. In addition, it is usually necessary to rely on a forest compass, DBH taper and RTK or handheld GPS to set up the plot. These instruments each have a single function and cannot achieve accurate positioning under the forest canopy. Therefore, it is necessary to update the existing equipment and technology. This study aimed to design. a multi-functional, high-precision, real-time. positioning intelligent tree-measuring instrument that integrates plot the set-up, DBH measurement, tree height measurement and tree position measurement. The instrument is based on the ultra-wideband positioning principle, sensor technology, image processing technology, trigonometric functions, tree surveying and other related theories and realizes the functions of plot set-up, tree position measurement, DBH measurement, tree height measurement and other functions. The device was tested in four square plots. The results showed that the root mean squared. error (RMSE). of the tree position estimates ranged from 0.07 m to 0.16 m, while the relative root mean squared error (rRMSE) of the DBH estimates of individual trees ranged from 3.01 to 6.43%, which is acceptable for practical applications in traditional forest inventory. The rRMSE of the tree height estimates ranged from 3.47 to 5.21%. Furthermore, the cost of this instrument is only about one-third that of traditional forestry survey tools, while the work efficiency is three times that of the traditional measurement methods. Overall, the results confirmed that the tree measuring instrument is a practical tool for obtaining. accurate measurements of the tree position, DBH and tree height for forest inventories.