Restoration Of Forest Ecosystems Research Articles

Ecological and cenotic features of natural regeneration of forests in the Left-Bank Polissya of Ukraine

The research relevance of the complex, multi-stage process of natural regeneration of forest communities, as well as interactions and transformations, is determined by the rapidly growing challenges posed by climate change, deforestation and biodiversity loss. The study aims to assess the state and to identify the ecological and coenotic specificity of natural seed regeneration of the leading forest-forming species of the Left-Bank Polissya of Ukraine. The study was carried out using a set of methods, primarily geobotanical, population and mathematical and statistical. The process of natural recovery was studied in communities that are typical for the region and belong to 42 syntaxa in the rank of associations and 24 syntaxa in the rank of association groups. The study revealed the specifics of such forest-forming species as Pinus sylvestris L., Quercus robur L., Acer platanoides L., Betula pendula Roth., Populus tremula L., and Tilia cordata Mill. The study established that the representation of the undergrowth of the main forest-forming species in the forest plant communities of the Left-Bank Polissya of Ukraine varies quite significantly. The study described the determinants of the species composition of restoration, including the peculiarities of seed (fruit) dispersion and the adaptive potential of plants. The study determined that the condition of the understory and its population density are determined by the level of soil moisture (the highest values of understory density in most species were recorded in forests with soils moistened at the level of fresh and wet hygro-tops), and this process may intensify against the background of climate change. The results of the study can be used to develop effective strategies for forest management, biodiversity conservation and sustainable forest management in the Left Bank Polissia region, which will help improve the environmental situation and create favourable conditions for the restoration of forest ecosystems

Effect of Vegetation Structure on Lift-Off and Dispersal Velocities of Diaspores with Different Morphological Characteristics in Secondary Wind Dispersal

Diaspore dispersal is crucial in shaping plant population dynamics, biodiversity, and ecosystem functions. The effect of the vegetation structure on the secondary wind dispersal of diaspores with different appendage types is not well understood. Using a wind tunnel and a high-definition video camera, we accurately measured the lift-off and dispersal velocities of diaspores from sixteen plant species across six wind velocities (2, 4, 6, 8, 10, and 12 m s−1) under six simulated vegetation structures. Vegetation structure and appendage type were pivotal factors, explaining 41.1% and 42.3% of the variance in lift-off velocity and accounting for 12.0% and 25.3% of the variability in diaspore dispersal velocity, respectively. Vegetation coverage was the main factor influencing near-surface wind velocity, and the lift-off and dispersal velocities of diaspores changed significantly when vegetation coverage exceeded 40%. Diaspores with one wing, having high lift-off velocities and low dispersal velocities, adopt the anti-long-distance wind dispersal strategy, whereas diaspores with pappus, having low lift-off velocities and high dispersal velocities, adopt the long-distance wind dispersal strategy. In contrast, diaspores with thorn, discoid, balloon, and four wings adopt the non-long-distance wind dispersal strategy, suitable for environments such as low-coverage deserts and desert steppes but not high-coverage typical steppes. This study could help comprehend the effect of the vegetation structure on the dispersal process of diaspores, which facilitate habitat restoration and biodiversity conservation of grassland and forest ecosystems.

Selecting Suitable Tree Species for Direct Seeding to Restore Forest Ecosystems in Northern Thailand

To upscale restoration of tropical forest ecosystems, direct seeding—sowing seeds directly into the ground—is potentially a more cost-effective technique than tree planting. However, its success is limited by seed predation, the harshness of environmental conditions on restoration sites and particularly by a lack of information about suitable tree species. Therefore, this study tested the suitability of 23 native forest tree species for direct seeding, to restore a biodiversity-rich, upland, evergreen forest in northern Thailand. Three replicate seed batches of each species were sown randomly in two degraded sites and in a tree nursery under controlled conditions. Seed removal and germination were monitored weekly until no further germination had occurred for more than a month. Subsequently, seedling yield, growth and species performance score were also monitored at appropriate intervals. Nine months after sowing, seed removal differed significantly among species but was generally low, with a cross-species average of 3.4% (±0.5 SE). Seed size was negatively correlated with seed removal. Eight species failed to germinate. Seed germination percentage varied widely among species. Cross-species average germination of the 15 species that germinated was 25% (±6.2 SE). Two species (Adenanthera microsperma and Alangium kurzii) were ranked as having high germination (>50%), five species (Choerospondias axillaris, Spondias pinnata, Diospyros glandulosa, Melia azedarach and Phyllanthus emblica) had medium germination (20–50%) and eight species had low germination (<20%). Following the first dry season, two of the fifteen germinated species failed to establish. Germination and establishment were influenced by seed size, seed storage behavior and successional status. A. microsperma, S. pinnata and C. axillaris are recommended for direct seeding based on their high species performance index values. This study further concluded that selecting desiccation-tolerant seeds, particularly those with medium-to-large sizes, could increase the chances of successful seedling establishment.

Facilitating early boreal forest succession on waste rock using Ramial Chipped Wood mulch: A five-year study

After a mine is closed, waste rock storage areas must be revegetated to facilitate the return of ecosystem services and meet legal and social expectations. The restoration of forest ecosystems on waste rock through spontaneous colonization associated with primary succession can take decades and is still poorly studied. Adding a mulch of ramial chipped wood (RCW) could improve the physicochemical properties and microclimate conditions of waste rock, thus facilitating substrate colonization by plants. In 2016, a fully randomized block design was installed on waste rock from a closed gold mine located in the boreal forest in Abitibi-Témiscamingue, Quebec, Canada. The design included four treatments: scarified waste rock as the control (WR), 2 cm of RCW mulch on top of scarified waste rock (RCW/WR), and 10 cm layer of sand on top of scarified waste rock with or without 2 cm of RCW mulch (RCW/S and S, respectively). Over a period of five years, we followed the natural colonization of forest species as well as abiotic (substrate microclimate conditions and physicochemistry) and biotic (herbaceous plant colonization) factors influencing woody plant colonization success. Six boreal woody species spontaneously colonized the area (five individuals per m2, on average, all species combined). Salix sp. and Picea glauca seedlings were more abundant on substrates with RCW mulch (especially sand) than those without mulch, and P. glauca had greater aerial biomasses with RCW mulch. Substrate water content during the growing season and the presence of the weed species Tussilago farfara were determining environmental factors in substrate colonization by Abies balsamea. In the absence of Tussilago farfara, RCW mulch increased A. balsamea colonization. RCW mulch increased the total cover of colonizing herbaceous plants (23.3–58.2%) as compared to mineral substrates alone (4.78–52.3%), which negatively affected the number of A. balsamea individuals. The colonizing herbaceous species were mostly primary succession species, Pilosella caespitosa, Anaphalis margaritacea, and Tussilago farfara being dominant; no exotic species were observed. The results highlight the potential of RCW mulch in promoting forest recolonization on waste rock, including mid-successional species like Picea sp., which could be useful for facilitating ecosystem succession in post-mining landscapes.

2021–2022年广东南岭站日尺度气象数据集

The mountainous forest and biodiversity ecological functional area of the Nanling Mountain forest ecosystem is one of the 25 key ecological functional areas in China, covering a variety of forest vegetation types, including tropical and subtropical moist broadleaf forests, coniferous broad-leaved evergreen mixed forest, and mountain top evergreen broad-leaved dwarf forest. The tropical and subtropical moist broadleaf forests are the most typical vegetation type in the Nanling Mountains. Monitoring the meteorological elements in the community can help understand the response mechanism of the tropical and subtropical moist broadleaf forests in the Nanling Mountains to climate change. Based on the Nanling Forest Ecosystem National Field Scientific Observation Research station ("Nanling Station" for short) in the Nanling Mountains, Guangdong, we carried out positioning research in Nanling National Nature Reserve. In this paper, we disclosed the raw data of 10 min average wind speed, precipitation, air temperature, air pressure, solar radiation (i.e. total radiation, reflected radiation, ultraviolet radiation, net radiation, photosynthetically active radiation) as well as relative humidity continuously collected in the subtropical evergreen broad-leaved forest area of the Nanling Station from 2021-2022 on a daily scale after data processing, quality control and evaluation. The dataset accessible to the public can serve as a valuable resource for further insights into the Nanling Mountain Forest Ecosystem, and provide foundation for efforts related to the restoration and protection of forest ecosystems.

Suitability assessment for forest landscape restoration based on species diversity conservation

Forest landscape fragmentation poses a significant challenge to the conservation of species diversity. Evaluating the suitability of forest landscape restoration (FLR) becomes essential as it promotes effective management of forest resources and protects species diversity. This study focused on deploying and testing a suitability evaluation framework system for FLR in the Saihanba area of Hebei, China. The framework system incorporated factors such as land cover type, landscape structure, soil quality, and topography. Using the matter-element model, the study evaluated the restoration suitability and identified priority restoration areas. The results revealed that land cover type and landscape structure were the primary factors influencing FLR in the study area. The suitable area for FLR in the study area was about 519.20 km2, accounting for 55.55% of the total area. The area of moderate, marginal, and unsuitable restoration accounted for 17.30%, 23.96%, and 3.18% of the study area, respectively. The suitable restoration areas predominantly consisted of natural secondary forest characterized by large patch areas, short distances between patches, and complex patch shapes. In the study area, the objective of FLR should be protect large and complex shaped patches of natural secondary forests for better conservation of species diversity. The FLR suitability evaluation conducted in this study provide a valuable guidance for promoting species-diversity conservation and restoration of forest ecosystems at the landscape scale in the study area and other similar regions.

Assessment of Temperate Deciduous Forest Communities and Structures after Restoration through the Multi-Reference Ecosystems Framework

The reference forest serves as a model for forest ecosystem restoration and can be employed to assess the vegetation of the Restored Forest, thereby confirming the success of restoration. When evaluating restoration, employing multireference forests is advantageous for discerning gradual changes in Restored Forests. However, in previous studies, their utilization has been limited to comparisons with individual ecosystems. Therefore, this study investigates the status of Restored Forests in previously damaged areas and their resemblance to reference forests across four forest types, namely Climax Forest (CF), Secondary Forest (SF), Restored Forest (RF), and Planted Forest (PF). Reference forests, serving as model targets for restoration, include CF and SF, while RF and PF represent the restoration forests. Six target sites within two temperate deciduous forests (Quercus acutissima and Quercus variabilis) were selected, and a comparative analysis of species diversity, dominance, and evenness was conducted. This study revealed that the dominant species in the top canopy of restoration forests mirrored those in reference forests, with Q. variabilis and Q. acutissima being prevalent. A similarity index of over 60% and a high correlation of 0.987 were observed in the top canopy layer between the reference and restored ecosystems (CF-RF/SF-PF). These findings enhance our understanding of the current status of Restored Forests and advocate for the utilization of multiple reference forests for successful restoration efforts.

Exploring the landscape pattern change analysis for the transboundary Nyungwe-Kibira Forest (2000–2019): a spatially explicit assessment

Introduction and aimEnsuring the protection and restoration of forest ecosystems is vital to maintaining and restoring ecological balance in deforested or degraded landscapes. However, sustainable development faces challenges from high human impacts on natural forest ecosystems, insufficient advanced conservation measures, and limited engagement of local communities in developing nations. The aim of this study was to explore the utility of spatial remote sensing datasets in examining the landscape pattern changes within the transboundary Nyungwe-Kibira Forest from 2000 to 2019. This aimed to emphasize the necessity of understanding the intricate dynamics of this ecosystem and its susceptibility to human activities in order to bolster diverse restoration initiatives throughout the region.MethodsThe landscape pattern change in the Nyungwe-Kibira between 2000 and 2019 was analysed using high-resolution Landsat data. This analysis encompassed an evaluation of the dynamics of changes in built-up, cropland, and forest areas within the region. Especially, primary data derived from the Landsat dataset and secondary data from reports such as the Outlook Report were employed to elucidate the ongoing landscape transformation within and surrounding the transboundary forest.Results and discussionThe analysis revealed a net change of +62.3% and +18.07% in built-up and cropland areas, resulting in a gross change of 14,133 ha and 6,322 ha in built-up and cropland areas, respectively. Furthermore, the forest experienced an overall gain of 9.11%, corresponding to a net loss of 6.92% due to deforestation, estimated at -14,764 ha. The analysis also indicated that built-up areas accounted for approximately 33.02% of the net forest loss, primarily affecting the northern edge of the Rwanda region, while cropland expansion contributed to a net loss of forest (-9.48%), predominantly impacting the southeast portion of the forest in Burundi. Additionally, the forest is predicted to decrease by 0.74% by 2030, with current findings showing aggregated forest and cropland at 66% and 7%, dissected rangeland at 24%, and created built-up areas at 3%. The findings indicate that the Nyungwe-Kibira Forest is undergoing notable transformations, highlighting the necessity of land-based projects and mitigation plans to facilitate the restoration of the forest from its historical changes. Without proactive measures, an ongoing decrease in forest area by 2030 is anticipated.

Dynamic restoration mechanism of plant community in the burned area of northeastern margin of Qinghai-Tibet Plateau.

Forest fires play a pivotal role in influencing ecosystem evolution, exerting a profound impact on plant diversity and community stability. Understanding post-fire recovery strategies holds significant scientific importance for the ecological succession and restoration of forest ecosystems. This study utilized Partial Least Squares Path Modeling (PLS-PM) to investigate dynamic relationships among plant species diversity, phylogenetic diversity, soil properties, and community stability during various recovery stages (5-year, 15-year, and 23-year) following wildfires on the northeastern margin of the Qinghai-Tibet Plateau. The findings revealed: (1) Over time, species richness significantly decreased (p< 0.05 or p< 0.01), while species diversity and dominance increased, resulting in uniform species distribution. Community stability progressively improved, with increased species compositional similarity. (2) Throughout succession, phylogenetic diversity (PD) significantly decreased (p< 0.01), accompanied by rising Mean Pairwise Distance (MPD) and Mean Nearest Taxon Distance (MNTD). Net Relatedness Index (NRI) shifted from positive to negative, indicating an increasing aggregation and dominance of plants with similar evolutionary traits in burned areas. Early succession witnessed simultaneous environmental filtering and competitive exclusion, shifting predominantly to competitive exclusion in later stages. (3) PLS-PM revealed that in the early recovery stage, soil properties mainly affected community stability, while species diversity metamorphosed into the primary factor in the mid-to-late stages. In summary, this study showed that plant diversity and phylogenetic variation were successful in revealing changes in community structure during the succession process. Soil characteristics functioned as selective barriers for plant communities during succession, and community stability underwent a multi-faceted and dynamic process. The soil-plant dynamic feedback continuously enhanced soil conditions and community vegetation structure thereby augmenting stability. Post-fire vegetation gradually transitioned towards the original native state, demonstrating inherent ecological self-recovery capabilities in the absence of secondary disturbances.

Strategic Assessment of the Impact of Forestry on the Environment to Achieve Sustainable Development

The relevance of the proposed topic is driven by global climate change and the urgent need to optimize the management of natural resources. Forests play a central role in the global carbon balance and are of great socio-economic importance for local communities. The research aims to analyze forest management strategies and their environmental impacts. The study focuses on forest ecosystems in different regions and climatic zones. The methodology is based on a comprehensive analysis of scientific literature, statistical data, and the examination of practical examples. The article highlights the dynamics of forest ecosystem restoration following different types of forestry interventions in different climatic zones, including the Ukrainian context. The impact of forest management on global carbon balances and the socio-economic sphere is assessed. The research shows that adaptive strategies can contribute to sustainable development and biodiversity conservation. The conclusions provide recommendations for the implementation of these strategies at the national level, especially in Ukraine.

Negotiating Environmental Crisis within Forest Ecosystem Restoration Projects in Puncak and Lombok, Indonesia

Negotiating Environmental Crisis within Forest Ecosystem Restoration Projects in Puncak and Lombok, Indonesia

Quercus wutaishanica shrub affects temperate forest community composition and soil properties under different restoration stage.

Quercus wutaishanica is the dominant tree species in the natural ecosystem restoration of temperate forests in China, and it plays an active role in maintaining ecological balance. However, little is known about how ecosystem versatility develops during the restoration of forest ecosystems dominated by Q. wutaishanica. In this study, we investigated the species composition of the Q. wutaishanica community, soil nutrients, and their functional traits at various restoration stages, and comprehensively analyzed the correlations among them. At the early stage of restoration (10 years of restoration), there were Spiraea pubescens and Syringa pubescens in Q. wutaishanica community (87% of the total species), while had a larger niche width. In the middle of restoration (30 years of restoration), shannon and evenness indices were the largest, while soil total carbon, ammonium nitrogen and chlorophyll content of Q. wutaishanica leaves were the highest; among them, soil total carbon was 15.7% higher than that in 10 years of restoration, 32.4% higher than that in 40 years of restoration, ammonium nitrogen was 71.7% higher than that in 40 years of restoration, and chlorophyll content was 217.9% higher than that in 10 years of restoration, and 51.8% higher than that in 40 years of restoration. At the later stage of restoration (40 years of restoration), Lonicera ferdinandii occupied the dominant ecological niche, and soil available nitrogen, available phosphorus content and leaf thickness were the largest; while AN was 10.9% higher than that of 10 years of restoration, 16.5% higher than that of 30 years of restoration, AP was 60.6% higher than that of 10 years of restoration, 21.6% higher than that of 30 years of restoration, leaf thickness was 22.3% higher than that of 10 years of restoration, 84.9% higher than that of 30 years of restoration. However, the restriction of various soil nutrients was reduced. Our study highlighted the effectiveness of soil resource availability in plant communities during restoration, reduced competition for light among plants, and altered species richness. Furthermore, changes in the interrelationship between plant community composition and leaf functional traits of the dominant species responded positively to community restoration. These results further deepen our understanding of forest management and restoration of forest communities. In the future, it is necessary to comprehensively consider the influence of various factors on forest community restoration.

The response of epiphytic lichens on living and dead Pinus sylvestris to prescribed fires of varying severity

Prescribed burning can be used to restore forest ecosystems degraded by anthropogenic pressures. However, some species such as epiphytic lichens may be vulnerable to fire. We studied the effects of fire on epiphytic lichens on living and dead Pinus sylvestris (Scots pine) by surveying lichens up to two meters on the trunks 21 years after experimental and replicated prescribed burnings in pine-dominated boreal forests in Finland. We investigated three types of stands that had faced different levels of fire severity: 1) unburned semi-natural mature stands (i.e., control sites), 2) burned semi-natural mature stands, and 3) burned retention groups on clearcut sites. In the semi-natural mature stands, the fires were low-severity surface fires and induced negligible mortality in P. sylvestris. In the retention groups, the fires induced high tree mortality and made fresh deadwood the dominant substrate type. Low-severity fires reduced the occurrence of several species, but usually did not eliminate them. High-severity fires eliminated some species, but the abundant deadwood frequently hosted some species that were absent or infrequent on the unburned sites. Thus, the fires had only small effects on total species richness. However, fires substantially changed species composition: they reduced the occurrence of species associated with late-successional habitats, while increasing the occurrence of early-successional species. We also found fires to decrease the occurrence of microlichens and increase that of macrolichens. The magnitude of the compositional changes increased with fire severity. Our findings indicate that the high quantities of fresh deadwood in post-disturbance forests provide habitat only to a limited portion of deadwood-associated lichens. Fire can increase landscape-scale variation in epiphytic lichen communities, but we observed negative effects, which increased with fire severity, on lichen flora of conservation concern. Thus, we recommend prescribed burning to be applied primarily in sites with a history of intensive management. Fire should be avoided in sites with substrates that are fire-sensitive and important to lichen diversity.

ECOLOGICAL STRATEGIES OF PLANTS IN THE PROCESS OF RESTORATION OF DISRUPTED NATURAL ECOSYSTEMS OF UKRAINIAN POLISSIA

Tasks related to the restoration of disturbed natural ecosystems are of theoretical and practical importance. Traditional approaches to remediation are often utilitarian. We often observe that the natural processes of ecosystem restoration occur faster and with better quality than those carried out by humans under similar conditions. The purpose of our work is to investigate the role of plants that have different ecological strategies during the process of restoration of disturbed ecosystems. The following tasks were outlined to achieve this goal: to identify groups of plants with different ecological strategies involved in the restoration of natural vegetation; develop models of vegetation restoration using plants with different ecological strategies. The materials of our research are standard geobotanical descriptions made on the territory of Ukrainian Polissia in the period from 2004 to 2023. We consider environmental strategies more broadly than R. Whittaker, L. H. Ramensky, J. Grim and E. Pianki in their classic works. The ecological strategies of plants differ in the way of spreading and reproduction, as well as in the signs of fixation on the soil; by methods of energy reservation; changing the environment around itself. The rate of restoration of natural ecosystems, as well as their characteristics, depend on the configuration of the disturbed area, the substrate of its surface, and the adaptive strategies of the plants that fall on it. The classification of adaptive strategies of species that affect the process of restoration of natural ecosystems is formed on the basis of the variety of methods of reproduction and distribution of fruits and seeds of autotrophs, as well as the peculiarities of their energy distribution in the reproduction process. The change in ecological strategies of species is because ecosystems are dynamic systems, therefore, during primary successions; disturbed ecotopes are most successfully populated by patient species, and during secondary ones by explerent species and violent species. Plants penetrate the primary substrate with the help of seeds, spores, or vegetative organs (most often rhizomes). In the early stages of primary succession, the seeds and spores of patient species are the most successful – those with low competitiveness and can achieve reproductive and vegetative success outside the communities. The balance of the amount of energy of Polissia pioneer patients is often shifted from supporting the vegetative part of the body to its seeds. Species that spread to pioneer substrates using rhizomes do not have such a limitation because they share a common distribution of matter and energy with the pioneer part of the community. Those species on the primary substrate, having no competitors, actively photosynthesize and share carbohydrates, while those on the formed substrate and have many competitors for solar energy share water and mineral nutrients. Global climate changes, which lead to xerophytization of Polissia and warm winters with little snow, are becoming an obstacle to the rapid natural restoration of pine forest ecosystems in large areas of disturbed areas.

Study on the Regeneration Probability of Understory Coniferous Saplings in the Liangshui Nature Reserve Based on Four Modeling Techniques

Forests are one of the most important natural resources for humans, and understanding the regeneration probability of undergrowth in forests is very important for future forest spatial structure and forest management. In addition, the regeneration of understory saplings is a key process in the restoration of forest ecosystems. By studying the probability of sapling regeneration in forests, we can understand the impact of different stand factors and environmental factors on sapling regeneration. This could help provide a scientific basis for the restoration and protection of forest ecosystems. The Liangshui Nature Reserve of Yichun City, Heilongjiang Province, is a coniferous and broadleaved mixed forest. In this study, we assess the regeneration probability of coniferous saplings (CRP) in natural forests in 665 temporary plots in the Liangshui Nature Reserve. Using Sentinel-1 and Sentinel-2 images provided by the European Space Agency, as well as digital elevation model (DEM) data, we calculated the vegetation index, microwave vegetation index (RVI S1), VV, VH, texture features, slope, and DEM and combined them with field survey data to construct a logistic regression (LR) model, geographically weighted logistic regression (GWLR) model, random forest (RF) model, and multilayer perceptron (MLP) model to predict and analyze the CRP value of each pixel in the study area. The accuracy of the models was evaluated with the average values of the area under the ROC curve (AUC), kappa coefficient (KAPPA), root mean square error (RMSE), and mean absolute error (MAE) verified by five-fold cross-validation. The results showed that the RF model had the highest accuracy. The variable factor with the greatest impact on CRP was the DEM. The construction of the GWLR model considered more spatial factors and had a lower residual Moran index value. The four models had higher CRP prediction results in the low-latitude and low-longitude regions of the study area, and in the high-latitude and high-longitude regions of the study area, most pixels had a CRP value of 0 (i.e., no coniferous sapling regeneration occurred).

Successful forest restoration using plantation at high deer density: How neighboring vegetation drives browsing pressure and tree growth

Browsing can be an environmental stress to forest ecosystems, where the composition and structure of plant communities depend on the balance between ungulate browsing and the ability of plants to tolerate and acclimate to this stressor. Tree planting is a management tool for restoring forest whose integrity has been compromised by the intensity and repetition of browsing. This tool may be insufficient when the stress leading to forest degradation is ongoing. Balsam fir (Abies balsamea (L.) Mill.) plantations are used on Anticosti Island (Quebec, Canada) to restore winter habitat for white-tailed deer (Odocoileus virginianus Zimmermann, 1780). To promote natural regeneration and growth of planted firs that are the staple winter forage of deer, enclosures were temporarily erected and deer densities reduced to decrease browsing pressure. The stress induced by heavy browsing at the time of fence removal and the density of competitors in regenerating cutblocks, however, could compromise fir growth and forest recruitment. Our objective was to identify factors influencing browsing intensity and balsam fir’s growth following fence removal. We aimed to identify factors influencing lateral browsing intensity and number of trunk reiterations on fir at the landscape scale, including distance and size of the surrounding forests, and at the local scale through intraspecific density-dependence and interspecific associative effects. We then sought to identify the stressors most influencing balsam fir growth among browsing variables and a neighborhood crowding index (NCI). We measured browsing intensity and growth of 114 balsam firs 8 years following planting and again 2 and 4 years after dismantling two management enclosures. At the landscape scale, our results showed that when balsam fir was more than 150 m from a forest edge, the probability of browsing was close to zero and consistently a low percentage of shelter area surrounding a focal fir led to a decrease in browsing pressure. At the local scale, intensity of lateral browsing increased with the NCI of white spruce (Picea glauca (Moench) Voss). Fir growth was negatively influenced by the additive effects of browsing and NCI. Finally, our results showed that 19.7% (95 %CI: 4.5%, 42.6%) of the effect of the surrounding vegetation on growth was mediated by browsing. The success of forest ecosystem restoration through planting depends on density of neighboring tree species that can generate environmental stress by influencing growth indirectly through browsing as well as directly through competition for resources.

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.

Secondary invasion by an invasive shrub limits native tree seedling growth in a size‐dependent manner following the eradication of a different invasive species in an island ecosystem

Following the control of an invasive tree species, native forest ecosystem restoration can be prevented by a secondary invasion by another invasive species that inhibits the reestablishment of native trees. In this study, we evaluated the effects of the invasive shrub Leucaena leucocephala on the initial growth of planted seedlings of four native tree species (Pandanus boninensis, Rhaphiolepis indica, Schima mertensiana, and Terminalia catappa) after eradication of the invasive tree Casuarina equisetifolia in the Ogasawara Islands in the northwestern Pacific Ocean. In a 24‐month field experiment, we compared the sizes of planted seedlings (diameter at ground level, height, and leaf number) among four treatments in a 2 × 2 design of initial seedling size (large vs. small) × L. leucocephala invasion (sowing L. leucocephala seeds vs. control). More than 75% of the seedlings (excluding S. mertensiana) survived regardless of the treatments. For all four species, initially large seedlings tended to become larger plants at the end of the experiment than initially small seedlings. We detected significant effects of L. leucocephala invasion on one or more plant size parameters in all four species. Seedlings grown in L. leucocephala invasion quadrats were smaller than those in control quadrats at the end of the experiment. We detected significant interactions between initial seedling sizes and L. leucocephala invasion for three species. Together, these results indicate that secondary invasion by L. leucocephala after controlling C. equisetifolia inhibits the initial growth of native tree seedlings, depending on their size at the time of invasion.

Tree diversity, vegetation structure and management of mangrove systems on Viti Levu, Fiji Islands

Mangrove forest ecosystems are critical natural resources, particularly in the South Pacific region. Mangrove forests in Viti Levu, Fiji’s main island, are threatened by infrastructure development activities and population growth. Consequently, the protection and restoration of mangrove forest are of utmost importance. This study investigated the diversity and structure of mangrove forest on Viti Levu to determine the most appropriate species for use in restoration projects. These species could enhance the management of mangroves in Fiji. Five sites were selected: Ellington Wharf (EW), Naboutini Village (NV), Nasese (NA), Suva City Council Park (SCCP) and the University of the South Pacific Upper Campus (UUC). The variations in the number of tree stumps from site-tosite highlighted differences in the degree of anthropogenic disturbances, EW was classified as an undisturbed site while NA was highly disturbed. The sites were examined using systematic line transects with random starting points. Continuous belt transects were established, along which 10 m × 10 m segments were selected as the primary plots (n = 100 primary plots). Tree species, stand structure, tree diameter and height, stem abundance, stand volume, basal area and natural regeneration were recorded at all sites. Five mangrove species (Rhizophora stylosa Griff., Bruguiera gymnorhiza (L.) Lam., Excoecaria agallocha (L.), Rhizophora samoensis (Hochr.) Salvoza, and Rhizophora × selala (Salvoza) Toml.) were identified. The species importance value indices were highest for R. stylosa at EW (264.0) and for B. gymnorhiza) at NV (175.2). All sites had at least some level of human disturbance but R. stylosa and B. gymnorhiza thrived regardless of the extent of anthropogenic impacts. Subsequently, R. stylosa and B. gymnorhiza are recommended for mangrove forest ecosystem restoration programmes in Fiji.

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.