Natural Forest Regeneration Research Articles

Quantification of Forest Regeneration on Forest Inventory Sample Plots Using Point Clouds from Personal Laser Scanning

The presence of sufficient natural regeneration in mature forests is regarded as a pivotal criterion for their future stability, ensuring seamless reforestation following final harvesting operations or forest calamities. Consequently, forest regeneration is typically quantified as part of forest inventories to monitor its occurrence and development over time. Light detection and ranging (LiDAR) technology, particularly ground-based LiDAR, has emerged as a powerful tool for assessing typical forest inventory parameters, providing high-resolution, three-dimensional data on the forest structure. Therefore, it is logical to attempt a LiDAR-based quantification of forest regeneration, which could greatly enhance area-wide monitoring, further supporting sustainable forest management through data-driven decision making. However, examples in the literature are relatively sparse, with most relevant studies focusing on an indirect quantification of understory density from airborne LiDAR data (ALS). The objective of this study is to develop an accurate and reliable method for estimating regeneration coverage from data obtained through personal laser scanning (PLS). To this end, 19 forest inventory plots were scanned with both a personal and a high-resolution terrestrial laser scanner (TLS) for reference purposes. The voxelated point clouds obtained from the personal laser scanner were converted into raster images, providing either the canopy height, the total number of filled voxels (containing at least one LiDAR point), or the ratio of filled voxels to the total number of voxels. Local maxima in these raster images, assumed to be likely to contain tree saplings, were then used as seed points for a raster-based tree segmentation, which was employed to derive the final regeneration coverage estimate. The results showed that the estimates differed from the reference in a range of approximately −10 to +10 percentage points, with an average deviation of around 0 percentage points. In contrast, visually estimated regeneration coverages on the same forest plots deviated from the reference by between −20 and +30 percentage points, approximately −2 percentage points on average. These findings highlight the potential of PLS data for automated forest regeneration quantification, which could be further expanded to include a broader range of data collected during LiDAR-based forest inventory campaigns.

Allowing natural forest regeneration to provide shelter for cocoa trees in tropical agroforestry

Allowing natural forest regeneration to provide shelter for cocoa trees in tropical agroforestry

Simple ecological indicators benchmark regeneration success of Amazonian forests

Natural regeneration of Amazon forests offers a promising strategy to mitigate forest loss and advance the goals of the UN Decade on Ecosystem Restoration. However, the vast variability in regeneration rates across environmental gradients and over time poses considerable challenges for assessing regeneration success and ecosystem services provision in human-modified landscapes. Here we compiled 448 plots from forest regeneration in the Amazon to investigate the drivers of regrowth capacity and identify robust ecological indicators. By modeling optimal successional trajectories, we estimated reference values for vegetation structure, diversity, and functioning. After 20 years, successful regeneration should reach a minimum basal area of 14 m². ha−¹, at least 34 tree species per 100 individuals, a structural heterogeneity index of 0.27, and 123 Mg.ha−¹ of aboveground biomass. These straightforward indicators and reference values provide a foundational framework for governments and practitioners to assess success and establish targets for Amazon restoration efforts.

The Impact of Structural Indicators and Game Browsing on the Natural Regeneration of Forest–Steppe Ecosystems Dominated by Deciduous Oak Species—A Case Study from the Krupina Plateau, Slovakia

The Impact of Structural Indicators and Game Browsing on the Natural Regeneration of Forest–Steppe Ecosystems Dominated by Deciduous Oak Species—A Case Study from the Krupina Plateau, Slovakia

New insights into a sensitive life stage: hydraulics of tree seedlings in their first growing season.

The first year in a tree's life is characterized by distinct morphological changes, requiring constant adjustments of the hydraulic system. Despite their importance for the natural regeneration of forests and future vegetation composition, little has been known about the hydraulics of tree seedlings. At different times across the first growing season, we analysed xylem area-specific (Kshoot_Axyl) and leaf area-specific (Kshoot_L) shoot hydraulic conductance, as well as embolism resistance of three temperate conifer trees, two angiosperm trees and one angiosperm shrub, and related findings to cell osmotic parameters and xylem anatomical traits. Over the first 10 wk after germination, Kshoot_Axyl and Kshoot_L sharply decreased, then remained stable until the end of the growing season. Embolism resistance was remarkably low in the youngest stages but, coupled with an increase in cell wall reinforcement, significantly increased towards autumn. Contemporaneously, water potential at turgor loss and osmotic potential at saturation decreased. Independent of lineage, species and growth form, the transition from primary to secondary xylem resulted in a less efficient but increasingly more embolism-resistant hydraulic system, enabling stable water supply under increasing risk for low water potentials.

Analyzing the impact of phosphorous and nitrogen on Castanopsis sclerophylla early growth stages

Plant growth elements, particularly nitrogen (N) and phosphorus (P) are vital for their growth and development, particularly for understory vegetation and their excess limits the net productivity of terrestrial ecosystems. This study focuses on the understory vegetation responds and adaptation to key essential nutrients under changing climate scenarios in subtropical evergreen broad-leaved forests, still needs research attention. this, we set up an experiment taking four treatments in a 50-year-old Castanopsis sclerophylla secondary forest under (a) control (CK), (b) N, (c) P, and (d) combined N and P addition, applied to natural forest regeneration seedlings of C. sclerophylla attained similar growth parameters of diameter of 3 cm and 10 cm height. In addition, carbon, N, P, and non-structural carbohydrates (NSC) were determined through the anthrone colorimetric approach in different parts of seedlings. Results show that the combined N + P application enhanced the N and P by 14.48 %−140.55 % in the seedlings in both dry and wet seasons, respectively. However, during wet season, the content of NSC in the plant leaves significantly exceeded under P addition. Remarkably, CK showed increased P in the growing season but lower during the dry season. Furthermore, the root starch content of seedlings showed a significant increase under the application of N and P compared to combined N + P, ranging between 45.60 % and 58.70 %. Overall, the plant growth is attributed to N and P intake. The nutrient addition and seasonal variations have a coupled effect on seedling growth as proved in the in the natural open forest experiment. The study outcomes emphasize that the alterations in NSC allocation in the roots and leaves of C. sclerophylla seedlings under N + P addition could enhance their adaptation to future global climate changes, drought conditions, and high N concentrations.

Global potential for natural regeneration in deforested tropical regions

Extensive forest restoration is a key strategy to meet nature-based sustainable development goals and provide multiple social and environmental benefits1. Yet achieving forest restoration at scale requires cost-effective methods2. Tree planting in degraded landscapes is a popular but costly forest restoration method that often results in less biodiverse forests when compared to natural regeneration techniques under similar conditions3. Here we assess the current spatial distribution of pantropical natural forest (from 2000 to 2016) and use this to present a model of the potential for natural regeneration across tropical forested countries and biomes at a spatial resolution of 30 m. We estimate that an area of 215 million hectares—an area greater than the entire country of Mexico—has potential for natural forest regeneration, representing an above-ground carbon sequestration potential of 23.4 Gt C (range, 21.1–25.7 Gt) over 30 years. Five countries (Brazil, Indonesia, China, Mexico and Colombia) account for 52% of this estimated potential, showcasing the need for targeting restoration initiatives that leverage natural regeneration potential. Our results facilitate broader equitable decision-making processes that capitalize on the widespread opportunity for natural regeneration to help achieve national and global environmental agendas.

Natural forest regeneration is projected to reduce local temperatures

Forest regeneration is a crucial strategy for mitigating and adapting to global warming. Yet its precise impact on local climate remains uncertain, a factor that complicates decision-making when it comes to prioritizing investments. Here, we developed global maps illustrating how natural forest regeneration influences key local climate drivers—land surface temperature (LST), albedo, and evapotranspiration—using models fitted at a 1-km spatial resolution with a random forest classifier. We found that natural forest regeneration can alter annual mean LST by 0.01 °C, −0.59 °C, −0.50 °C, and −2.03 °C in Boreal, Mediterranean, Temperate, and Tropical regions, respectively. These variations underscore the region-specific effects of forest regeneration. Importantly, natural forest regeneration reduces LST across 64% of 1 billion hectares and 75% of 148 million hectares of potentially restorable land under different scenarios. These findings improve understanding of how forest regeneration can help regulate local climate, supporting climate adaptation efforts.

One Health, One Forest: Harnessing Reclaimed Wood as a Sustainable Solution

Deforestation is a multifaceted and wicked problem characterized by its complexity and resistance to straightforward solutions. The issue is driven by human activities and has severe ecological, socio-economic, and climatic consequences. Between 1990 and 2015, approximately 129 million hectares of forest were lost globally, a trend contributing to biodiversity loss, increased carbon dioxide emissions, and climate change. In Canada, deforestation due to logging significantly impacts the boreal forests, with consequences such as habitat fragmentation affecting species like the threatened boreal caribou. The Canadian logging industry aims to provide essential raw materials while fostering economic growth and employment, supplying critical resources for sawmills, planing mills, shingle mills, and pulp and paper industries. Despite economic benefits, logging, particularly clearcutting, disrupts natural forest regeneration, soil composition, and water cycles, leading to long-term ecological consequences. The One Health approach, integrating human, non-human animal, and environmental health, is proposed to address this issue sustainably. Actions like those by Forests Ontario and Evergreen focus on reforestation and urban greening, while companies like Consolidated Pallet Co. promote wood recycling. This action plan showcases the potential for community-driven solutions to reduce environmental footprints, enhance sustainability, and foster economic and social well-being.

Плотность всходов сосны обыкновенной в сосновых лесах под влиянием выбросов Карабашского медеплавильного комбината и лесных пожаров

We assessed the features of natural pine regeneration in forests with different ages of ground fires in the Southern Urals depending on the level of heavy metal pollution. Using the materials obtained from 81 sample plots laid in maturing, mature and over-mature pine forests of natural origin in three types of forest growth conditions (TFGC 1 – TFGC 3), the relationship between the density of pine seedlings and the state of forest stands (crown density, stand age, vital status index), with the characteristics of vegetation condition (total number of species, total projective cover of herb-shrub layer, projective cover of bryophytes layer), with external influences (pollution level, distance from emission source, duration of fire disturbance), and with the methodological features of the study (accounting year) was analyzed. The high variability of estimates of the density of pine seedlings did not allow us to identify the relationship between the density of seedlings and the level of pollution and/or fire disturbances. The density of seedlings is nonlinearly related to the protective cover of the herb-shrub layer. With increasing coverage of the herb-shrub layer, the density of seedlings increased in areas with high levels of pollution and decreased in areas with background pollution.

Governance and policy constraints of natural forest regeneration in the Brazilian Amazon

Governance and policy constraints of natural forest regeneration in the Brazilian Amazon

Smallholders' perspectives, motivations, and incentives for restoring the Brazilian Atlantic Forest

Ecosystem restoration, recognized as a critical strategy for climate change adaptation and mitigation, faces significant challenges in achieving widespread implementation. A particular facet of this challenge lies in the active involvement of rural landowners. Our study aimed to understand rural landowners' perspectives, motivations, and characteristics that influence their participation in restoration projects in the Atlantic Forest of southeastern Brazil. Qualitative content analysis was conducted on 68 semi‐structured interviews with two groups of landowners: 36 who received support and 32 who did not receive project support from a local non‐governmental organization to restore native forests on their landholdings. Approximately three‐quarters of the sample are classified as smallholders (<80 ha). The main difference between the two groups is the dependence on agricultural production as the main source of income, with 22% of farmers in the supported group and 72% in the unsupported group. This socio‐economic characteristic appeared to influence the decision to restore native forest. Farmers' focus tends to be linked to rural production, and the main obstacle to restoration was the loss of productive land. They usually allow natural forest regeneration to establish on slopes. The other type of landowner (lifestylers) mainly restored land through planting of seedlings, with the main barrier being the cost of restoration. Both groups had water conservation as their main motivation for restoration. Our study shows that understanding the perspectives and motivations of the diversity of rural landowners is crucial to effectively engage them and address the socio‐economic feasibility of different restoration approaches.

Cost-effectiveness of natural forest regeneration and plantations for climate mitigation

Mitigating climate change cost-effectively requires identifying least-cost-per-ton GHG abatement methods. Here, we estimate and map GHG abatement cost (US$ per tCO2) for two common reforestation methods: natural regeneration and plantations. We do so by producing and integrating new maps of implementation costs and opportunity costs of reforestation, likely plantation genus and carbon accumulation by means of natural regeneration and plantations, accounting for storage in harvested wood products. We find natural regeneration (46%) and plantations (54%) would each have lower abatement cost across about half the area considered suitable for reforestation of 138 low- and middle-income countries. Using the more cost-effective method at each location, the 30 year, time-discounted abatement potential of reforestation below US$50 per tCO2 is 31.4 GtCO2 (24.2–34.3 GtCO2 below US$20–100 per tCO2)—44% more than natural regeneration alone or 39% more than plantations alone. We find that reforestation offers 10.3 (2.8) times more abatement below US$20 per tCO2 (US$50 per tCO2) than the most recent IPCC estimate.

Pattern of water use by Tamarix ramosissima seedlings in floodplains under varied groundwater depths in the hinterland of the Taklimakan Desert

The water use of Tamarix ramosissima Ledeb. seedlings after flooding were analyzed both to explore the maintenance mechanism and pattern of natural regeneration of riparian forest, which will provide a scientific basis for restoration of desert riparian forest and ecosystem stability in the lower reaches of inland rivers of arid regions. This study area was located in the hinterland of the Taklimakan Desert in Xinjiang, China. Tamarix ramosissima seedlings growing on different groundwater depths at the river floodplain were used as the study system. The rooting depths of T. ramosissima seedlings with different basal stem diameters were ascertained by the root excavation method. The water source for the T. ramosissima seedlings was clarified using hydrogen and oxygen stable isotope methods, and the water use efficiency of T. ramosissima seedlings was investigated by stable carbon isotope (δ13C) analysis. As the basal stem diameter classes of the T. ramosissima seedlings increased, their root depths increased. As the groundwater depth increased, the seedlings changed from primarily utilizing deep soil water to utilizing shallow soil water. In the three sample sites, the average depth of water uptake of the seedlings with basal stem diameters of 0–5 mm was 110.5, 44.1 and 39.1 cm, respectively, and that of seedlings with basal stem diameters of 5–11 mm was 83.8, 73.6 and 37.7 cm, respectively. As groundwater depth increased, the average water uptake depth of the seedlings gradually became shallower. There was no significant difference in the δ13C values of leaves under different groundwater depths, indicating that the seedlings were not subjected to water stress. Thus, surface water played a greater role than groundwater in T. ramosissima seedling water utilization. Therefore, when analyzing ecological water conveyance patterns, attention should be paid to T. ramosissima located in areas with deep groundwater. Shallow-rooted seedlings with small basal stem diameters face an increased risk of wilting if they do not receive timely recharges of surface water. Data AvailabilityAll data generated or analyzed during this study are included in this published article.

Growth stimulant influence on biometric indicators of oak seedlings in the Bukovyna Sub-Carpathian region

The use of growth stimulants for the cultivation of oak seedlings in the Bukovyna Sub-Carpathian region allows to accelerate their development and increase their sustainability in an environment where there is no natural forest regeneration. The aim of the study was to evaluate the effect of growth stimulants at different multiplicity of treatments during the growing season on the biometric parameters of Quercus robur L. Seedlings were grown in Ecotherm containers in the glasshouse of the base nursery. The composition of the substrate for filling the containers is a mix of peat, sand and black soil in equal proportions with mycorrhiza from under the forest canopy of oak stands. The results of the effect of growth stimulants on the biometric parameters of one-year-old seedlings of common oak with a closed root system are presented. Plant growth stimulants were used for spraying and irrigation seedlings during their cultivation. The results of the research indicate a positive effect of the use of growth stimulants on the seedlings of common oak. All experimental variants showed a positive effect on the biometric parameters of one-year-old oak seedlings at three, six and nine times of feeding with growth stimulants during the growing season. The difference in the variants with the use of plant growth stimulants compared to the control in height is up to 27%, in the length of the root system – up to 43%, and in the total length – up to 29%, accordingly, depending on the dose of the stimulants and the frequency of treatment during the growing season. Refined data on the biometric parameters of one-year-old seedlings of common oak with a closed root system grown in closed ground conditions were obtained. The data obtained are useful for forest restoration in regions with damaged or degraded ecosystems where natural regeneration is limited

A Local-Scale, Post-Fire Assessment in a Double-Burned Area: A Case Study from Peloponnisos, Greece

In the summer of 2021, Greece experienced significant forest fires and mega-fires across multiple regions, leading to human casualties and damage to the natural environment, infrastructure, livestock, and agriculture. The current study aims to assess the ecosystem condition in terms of the natural regeneration and soil conditions of an area burnt by a forest fire (2021), specifically in the Ancient Olympia region situated in West Peloponnese (Ilia Prefecture), Greece. A standardized field sampling methodology was applied to record natural regeneration at chosen sites where a forest fire had also previously occurred (in 2007), resulting in the natural re-growth of the Pinus halepensis forest. Furthermore, an analysis was conducted on the geochemical, mineralogical, and sedimentological properties of soils obtained from this location. The findings of the research demonstrate the decline in the established natural regeneration of the Pinus halepensis forest and the overall tree layer. Species characteristic of post-fire ecological succession were observed in the shrub and herb layers, displaying varying coverage. The examination of soil mineralogy, sedimentology, and geochemistry indicated that the soil characteristics in the area are conducive to either natural or artificial regeneration. Ultimately, recommendations for landscape rehabilitation strategies are provided to inform decision-making processes, considering future climate conditions.

Features of the structure of the herbaceous cover and natural regeneration in the spruce forests of the Kologrivsky Forest Nature Reserve

The aim of the study was to identify the features of the structure of the herbaceous cover and natural regeneration in the southern taiga spruce forests of the Kostroma region using the example of the Kologrivsky Forest Nature Reserve. To achieve this goal, twelve temporary square sample plots (SP) with an area of 0.0625 ha were established. Forest type, canopy density, soil and topography were determined. To characterize the forest stands, a taxonomic survey of the sample plots was carried out. To describe the vegetation cover, a combined method was used, including the Braun-Blanke and Drude-Uranov methods, which assumes the distribution of typical plant complexes over a large number of plant species growing together. Geobotanical descriptions were processed according to the method of D.N. Tsyganov, which consisted in using two tables: ecological amplitudes of species and scales of factors. Correlation analysis was used for data processing. The obtained statistical data set was presented in histograms and graphs for the sake of clarity. The frequency of occurrence, errors, participation rate, and average projective cover of the species were calculated according to generally accepted methods. In the course of the work, all sample plots were characterized by a tree-by-tree census. As the sample plots were located in very different parts of the reserve, the taxonomic indicators varied. In most cases, however, the dominant species was spruce. Its viable regrowth was 95%, indicating a high renewal potential. In the studied forest areas, the dominant species of the living ground cover were Northern linseed (Linnaea borealis) and blueberry (Vaccinium myrtillus), oak fern (Gymnocarpium dryopteris) and wood sorrel (Oxalis acetosella). The practical significance of the conducted research lies in the expansion of the ideas about the structure of the herbaceous cover formed under the canopy of spruce forests in the conditions of the Kologrivsky Forest Nature Reserve, as well as about the peculiarities of the process of natural regeneration in different conditions of the growth site.

Impact of salvage logging on short-term natural regeneration in montane forests of the Alps after large windthrow events

Wind disturbances are one of the main drivers of forest dynamics in Europe, shaping forest stands and modifying the ecosystem services provisioning. Salvage logging is often most common strategy adopted after a high-severity disturbance in managed stands. Understanding natural regeneration dynamics including their interaction with the logging operations, is crucial to understand how forests will be changing under a climate with increasing variability and to design adequate adaptive post-disturbance management strategies. In this study, we focused on 148 stands damaged by storm Vaia (2018). The aim was to analyze natural regeneration dynamics under different logging systems and to investigate influences of site characteristics and disturbance legacies on sapling growth and seedling emergence. The sampling protocol consisted of one transect per stand, perpendicular to one of the intact forest edges, and with a length of 80 m. Along the transect, we collected soil cover, natural seedling and sapling stem density, and deadwood quantity in four sample plots of 3 m radius each at distances of 0, 20, 40, and 80 meters from the edge (592 plots in total). Regeneration species composition was mainly driven by previous stand composition, with some exceptions depending on seed dispersal strategy. Distance from the edge significantly influenced seedlings and saplings occurrence in large gaps and affected the browsing damage percentage, together with deadwood presence. According to GLM’s models, distance from the edge, elevation, and logging methods influenced seedling establishment. At the same time, species characteristics, edge structure, deadwood and logging damages significantly influenced pre-storm seedlings and saplings presence and health. In conclusion site factors, disturbance legacies, and logging strategies are key points to consider in post-disturbance management for a fast forest recovery.

High potential but little success: ungulate browsing increasingly impairs silver fir regeneration in mountain forests in the southern Swiss Alps

Abstract Sustainable regeneration of silver fir (Abies alba Mill.) is important for maintaining and improving the future resilience and protective capacity of mountain forests in the southern Swiss Alps. However, increasing densities of wild ungulates, such as red and roe deer, can hamper the regeneration success of silver fir. A comprehensive understanding of forest–wildlife interactions is essential to plan concrete measures for improving the adaptation potential of mountain forests. Here, we monitored the dynamics of natural silver fir regeneration in mountain protective forests. This study encompassed 30 unfenced permanent plots across two sites, Lostallo and Soazza, located in Valle Mesolcina in the southern Swiss Alps. These sites were selected for their comparable ecological characteristics related to silver fir regeneration, yet contrasting densities of mature, seed-bearing silver fir trees. We recorded the number of seedlings (<10 cm height) and saplings (10–200 cm height), and repeatedly assessed height growth, frequency, and intensity of ungulate browsing on saplings in the summers 2016, 2019, and 2022. In 2022, we additionally recorded the presence of browsing on other tree species in the unfenced plots and the height growth increments of silver fir saplings in pre-existing fences. On average, 509 silver fir seedlings/ha were present in the study area, but there was a lower density of saplings (382 saplings/ha). Between 2016 and 2022, the browsing frequency on silver fir saplings increased from 33 per cent to nearly 100 per cent, accompanied by a significant rise in browsing intensity. Furthermore, sapling height growth from 2019 to 2022 was significantly reduced or even negative in the unfenced plots as compared to the growth of saplings in the fenced plots. The observed seedling density indicated a good potential for natural regeneration of silver fir, irrespective of the differences in the density of seed-bearing trees between the two sites. However, the increased ungulate browsing impaired successful regeneration in the considered mountain forests in the southern Swiss Alps. Thus, without an effective control of ungulate browsing, silver fir may not be able to substantially contribute to the transition to more resilient and future-proof mountain forests.

Neighborhood Competition and Understory-Associated Vegetation Are Important Factors Influencing the Natural Regeneration of Subtropical Mountain Forests

Natural regeneration is deemed essential for maintaining biodiversity and ecosystem stability. Previous studies, however, have primarily concentrated on regions exhibiting limited environmental and climatic variability, overlooking the classification of natural regeneration based on age and source. Research conducted at the mesoscale, characterized by increased environmental variability and the incorporation of neighborhood competition and understory-associated vegetation, enhances our comprehension of the multifaceted influences on natural regeneration. To comprehend this issue, this study implemented 60 plots, each measuring 20 m × 20 m, across five distinct areas of Chongqing, China. Twenty explanatory variables were chosen from five diverse categories: understory vegetation, neighborhood competition, stand structure, climatic factors, and environmental factors. And the naturally regenerated species were classified into seedlings and saplings, as well as endogenous and exogenous species, based on their age and origin. We examined the response of the different categories of natural regeneration to various factors and constructed a structural equation model (SEM) for significant factors to investigate their direct and indirect effects on natural regeneration. A total of 61 regenerated tree species belonging to 29 families and 42 genera were found in the study area, and the naturally regenerating species with high importance values were Quercus fabri, Robinia pseudoacacia, Alangium chinense, Cunninghamia lanceolata, and Ligustrum lucidum. It was found that neighborhood competition and understory-associated vegetation explained the largest proportion (more than 50%) of the variation in the different categories of natural regeneration, and forests with clumped distribution (W), a high mingling index (M) and strong competition (H) had a reduced natural regeneration capacity. Understory-associated herbs significantly reduced natural regeneration and the crowdedness index (C) significantly inhibited the understory-associated herbs, thus indirectly promoting natural regeneration. The shrub cover is significantly and positively correlated with the number of naturally regenerated plants and can be used as an indicator of a forest community’s regeneration potential. Understanding the differences in the importance of various factors at the mesoscale, as well as their direct and indirect impacts, can help us further comprehend the mechanisms of natural regeneration and provide a foundation for the sustainable development of forests.