Natural Regeneration Potential Research Articles

Integrating both restoration and regeneration potentials into real-world forest restoration planning: A case study of Hong Kong

Forest restoration is a vital nature-based solution for mitigating climate change and land degradation. To ensure restoration effectiveness, the costs and benefits of alternative restoration strategies (i.e., active restoration vs. natural regeneration) need to be evaluated. Existing studies generally focus on maximum restoration potential, neglecting the recovery potential achievable through natural regeneration processes, leading to incomplete understanding of the true benefits and doubts about the necessity of active restoration. In this study, we introduce a multi-stage framework incorporating both restoration and regeneration potential into prioritized planning for ecosystem restoration. We used the vegetated landscape of Hong Kong (covering 728 km2) as our study system due to its comprehensive fine-resolution data and unique history of vegetation recovery, making it an ideal candidate to demonstrate the importance of this concept and inspire further research. We analyzed vegetation recovery status (i.e., recovering, degrading, and stable) over the past decade based on the canopy height data derived from multi-temporal airborne LiDAR. We assessed natural regeneration potential and maximum restoration potential separately, producing spatially-explicit predictions. Our results show that 44.9% of Hong Kong's vegetated area has showed evidence of recovery, but remaining gains through natural regeneration are limited, constituting around 4% of what could be attained through active restoration. We further estimated restoration priority by maximizing the restoration gain. When prioritizing 5% of degraded areas, the increment in canopy height could be up to 10.9%. Collectively, our findings highlight the importance of integrating both restoration and regeneration potential into restoration planning. The proposed framework can aid policymakers and land managers in optimizing forest restoration options and promoting the protection and recovery of fragile ecosystems.

Diversity of Treatments in Overcoming Morphophysiological Dormancy of Paeonia peregrina Mill. Seeds.

Paeonia peregrina Mill. is a protected, herbaceous species native to Southeastern Europe and Turkey. Due to its vulnerability, it has to be protected both in its natural habitats and through cultivation. Peonies are known to have a low potential for natural regeneration due to their seed dormancy, low germination rate, and long germination period. In this study, treatments with gibberellic acid (GA3 150, 200, 250, 300, and 350 mg L-1 GA3) and warm (at 20/16 °C day/night regime) and cold stratification (at 4 °C) were used to accelerate dormancy release and increase the germination rate. The seeds of P. peregrina from four natural habitats in Serbia and the Institute's collection were collected and analyzed. They showed an underdeveloped embryo that needs to grow inside the seed before it can germinate. The application of GA3 accelerated each stage of germination (seed coat rapturing, hypocotyl dormancy release, and epicotyl dormancy release) for approximately 10 days compared to the control. It was also found that two-day imbibition with 200 mg L-1 GA3 significantly accelerated and equalized germination. Higher GA3 concentrations had a more pronounced impact on each stage but also resulted in greater seed infection after the seed coat rupture, elongated and weak seedlings, while lower concentrations did not result in obtaining uniform seedlings. There were no significant differences observed between localities. Restoring P. peregrina through seeds and nursery-produced plants is crucial for conserving the genetic diversity of the tested species.

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.

Eucalyptus productive matrix influences the soil seed bank in southern Brazil

<i>Eucalyptus </i>species are cultivated for various purposes around the world, mainly because they adapt well and grow quickly. These productive matrices of planted forests are common in Brazil, added to which, areas of native vegetation are requirements of environmental legislation. Although eucalyptus plantations are widely distributed in Brazil, little is known about the soil seed bank (SSB) in the eucalyptus productive matrix (EPM). We aim to understand how the EPM made up of eucalyptus plantations and native forest remnants affect the SSB in the Brazilian Pampa. Samples of the SSB of EPM were collected and monitored for six months in a shade house. We evaluated seedling emergence, richness, composition, ecological characteristics of the species, diversity, and floristic similarity. We recorded a high rate of seedling emergence, species richness, and different life forms and native species in all EPM treatments, however the similarity between native remnants and eucalyptus plantations was low. The size and level of conservation of native remnants and the position and management of eucalyptus sites in the EPM influenced the diversity and composition of species. Eucalyptus plantations contain SSBs with potential for natural regeneration when they are in a landscape that maintains conserved native forest remnants. These results expand the knowledge of the SSB in EPM and can support actions in ecological restoration projects.

Camptostemon philippinensis, a new record of endangered mangrove species in the Balikpapan Bay, East Kalimantan, Indonesia

Background Camptostemon philippinensis, found in mangrove forests in Indonesia and the Philippines, is listed as endangered on the International Union for Conservation of Nature (IUCN) Red List. It is found primarily in isolated mangrove forests in Kalimantan (Indonesian Borneo) and Sulawesi in Indonesia. Despite significant studies on mangrove biodiversity in this region, the occurrence of C. philippinensis in Balikpapan Bay, East Kalimantan, is not extensively recorded. Methods The study was conducted by exploring the mangrove forests along Balikpapan Bay. The first survey of about 200 km was conducted to observe mangrove vegetation and found one C. philippinensis tree. The second survey focused on the area around the first discovered C. philippinensis tree to census and record its growth stage and distribution. Results The study recorded a population of 527 individuals of C. philippinensis in Pantai Lango Village, East Kalimantan, dominated by seedlings. The high number of seedlings indicates good natural regeneration potential, but the low number of trees indicates intense competition for space in a restricted habitat. This species inhabits a small and restricted area in Balikpapan Bay, in the middle area of Balikpapan Bay, and is associated with other mangrove flora, such as Rhizophora apiculata, Rhizophora mucronata, Sonneratia alba, Avicennia alba, Lumnitzera littorea, Osbornia octodonta, Ceriops tagal, and Xylocarpus granatum. Conclusions C. philippinensis is vulnerable to habitat damage from anthropogenic activities, which could lead to local extinction. Its natural habitat in Balikpapan Bay also has the potential to be under pressure due to the development of Indonesia’s new capital city (Ibu Kota Nusantara/IKN). It emphasizes the need to understand the ecological role of this protected flora in the natural habitat of protected fauna (the proboscis monkey). Documenting the population of C. philippinensis is crucial for conservation efforts, including propagation and understanding its ecological role.

Floristic Composition, Diversity, and Regeneration of Woody Plant Species of Dabal Forest in Southeastern Ethiopia: Implication for Conservation.

Floristic composition, population structure, and regeneration status of woody species of Dabal forest found in East Hararghe zone of Oromia Regional State, Ethiopia, were studied. Vegetation data were obtained from 52 main plots of 20 × 20 m for mature woody species and 5 subplots of 5 × 5 m for seedlings and saplings. Density and dbh of each live woody plant species found in each sample plot were recorded. Frequency, basal area, importance value, and Shannon-Wiener diversity indices were also computed. Totally 59 woody plant species distributed in 33 families were documented. Of these, 45.80, 44.10, and 5.08% were shrubs, trees, and lianas, respectively. Species diversity and evenness indices were 3.56 and 0.87, respectively. Stem count of all woody species was 3379 stems ha-1. Out of this, 44.6, 30.8, and 24.59% were seedlings (dbh <3.5 cm), saplings (dbh between 3.5 and 10 cm), and mature (dbh >10 cm) individuals, respectively. Total basal area of all individuals with dbh ≥3.5 cm was 29.88 m2 ha-1. Juniperus procera, Cupressus lusitanica, Eucalyptus globulus, Afrocarpus falcatus, Eucalyptus camaldulensis, Myrsine africana, Maytenus undata, Hagenia abyssinica, Ekebergia capensis, and Cordia africana were species with top ten IVI. Most of these species were top densest, dominant, and frequent. Analysis of population structure based on pooled densities of all species in each dbh class showed that density of seedling > sapling > mature individuals, signifying healthy population structure with good natural regeneration potential. On individual basis, however, 35.6 and 8.5% of species showed fair and poor regeneration statuses, respectively, that deserve attention for conservation.

Assessing the Natural Regeneration Potential of Senegalia senegal by Rejection in Chad: Implications for Sustainable Management

The study of the potential of natural regeneration assisted by weaning of white gum was carried out in Mandalia, a locality located about 50 km from N'Djamena and its surrounding area. Inductions of shoots by weaning were carried out at two sites, one a Senegalia senegal Park and the other a grazing area. In the S. senegal parks, most of the shoots were underground. On the other hand, on the grazing land, most of the shoots were stump shoots. There was no significant difference between the number of shoots in the S. senegal park and in the grazing land. The survival rate of underground shoots at weaning showed a low value of less than 25%. In the Acacia Park, the correlation between survival and shoot size was 80.28%. However, in the grazing area, the survival rate was 50.69%. These results show that the site does not significantly influence the fate of the weaned underground discharge. It is clear from this study that a sustainable management plan for S. senegal is urgently required. To this end, studies on varietal selection and domestication of S. senegal should be undertaken as soon as possible. Raising farmers' awareness of the need to protect offshoots in agrosystems and promoting assisted natural regeneration in agrosystems would also enable them to be conserved by local populations and gradually domesticated in the short term.

Post-fire recovery of vegetation in the Chornobyl Radiation and Ecological Biosphere Reserve

ABSTRACT Fires significantly affect the structure and diversity of vegetation. Natural recovery of vegetation after fires in the Chornobyl Exclusion Zone is of special interest because of its status as a nuclear disaster area. This is the first assessment of the potential for natural regrowth of forest and post-fire succession after the catastrophic fires of 2020 that scorched 62 000 ha of forest across the territory. Most of these areas (>80%) have high potential for natural regeneration but, in the first instance, forest species are commonly replaced by wasteland weeds, some of them invasive; 10 alien plant species were identified in the studied plots. Megafires facilitate vegetation shifts and opportunities for invasive species, especially in the early stages of succession.

Camptostemon philippinensis, a new record of endangered mangrove species in the Balikpapan Bay, East Kalimantan, Indonesia

Background Camptostemon philippinensis, found in mangrove forests in Indonesia and the Philippines, is listed as endangered on the International Union for Conservation of Nature (IUCN) Red List. It is found primarily in isolated mangrove forests in Kalimantan (Indonesian Borneo) and Sulawesi in Indonesia. Despite significant studies on mangrove biodiversity in this region, the occurrence of C. philippinensis in Balikpapan Bay, East Kalimantan, is not extensively recorded. Methods The study was conducted by exploring the mangrove forests along Balikpapan Bay. The first survey of about 200 km was conducted to observe mangrove vegetation and found one C. philippinensis tree. The second survey focused on the area around the first discovered C. philippinensis tree to census and record its growth stage and distribution. Results The study recorded a population of 527 individuals of C. philippinensis in Pantai Lango Village, East Kalimantan, dominated by seedlings. The high number of seedlings indicates good natural regeneration potential, but the low number of trees indicates intense competition for space in a restricted habitat. This species inhabits a small and restricted area in Balikpapan Bay, in the middle area of Balikpapan Bay, and is associated with other mangrove flora, such as Rhizophora apiculata, Rhizophora mucronata, Sonneratia alba, Avicennia alba, Lumnitzera littorea, Osbornia octodonta, Ceriops tagal, and Xylocarpus granatum. Conclusions C. philippinensis is vulnerable to habitat damage from anthropogenic activities, which could lead to local extinction. Its natural habitat in Balikpapan Bay also has the potential to be under pressure due to the development of Indonesia’s new capital city (Ibu Kota Nusantara/IKN). It emphasizes the need to understand the ecological role of this protected flora in the natural habitat of protected fauna (the proboscis monkey). Documenting the population of C. philippinensis is crucial for conservation efforts, including propagation and understanding its ecological role.

Natural restoration exhibits better soil bacterial network complexity and stability than artificial restoration on the Loess Plateau, China

Natural restoration (NR, e.g., secondary succession) and artificial restoration (AR, e.g., afforestation) are key approaches for rehabilitating degraded land; however, a comparative assessment of microbial network between these approaches is lacking. We compared bacterial networks under NR and AR in two different watersheds on the Loess Plateau. Our findings revealed significantly heightened network complexity under NR compared to AR, including metrics such as node, edge, modularity, degree, centrality, and keystone nodes. NR's network robustness exceeded AR by 19.45–35.9% and 7.79–17.74% in the two watersheds, aligning with the ecological principle that complexity begets stability. The significantly higher negative/positive cohesion and natural connectivity under NR also support its better network stability than AR. Integrated analysis of paired sequencing data from five Loess Plateau studies conducted on the Loess Plateau further confirmed the higher complexity and stability of bacterial networks under NR. Further analysis unveiled “biological interactions” as primary drivers of bacterial co-occurrence (on average 84.21% of links), surpassing the influence of environmental filtering (5.17%) or dispersal limitation (4.2%). Importantly, networked communities under NR exhibited generally stronger linkages with various ecosystem function than AR. Overall, our study provides insights into vegetation restoration strategies from the perspective of microbial network, underscoring natural regeneration's potential as a superior remedy for degraded-land restoration.

Mapping the regeneration potential of native vegetation in cultivated pastures of the Brazilian Cerrado.

The Brazilian Cerrado is a hotspot of biodiversity conservation and an important global agricultural region. Cultivated pastures under different degradation levels are dominant in the landscape and are being targeted for sustainable agricultural intensification and restoration of native vegetation. In this study, we classified the cultivated pastures of the Brazilian Cerrado according to their potential for natural regeneration, based on field surveys and environmental predictors. We surveyed the native vegetation cover in 186 plots distributed along 93 cultivated pastures. The environmental predictors considered in this study were the proportion of sand in the soil, cation exchange capacity, climate water deficit, pasture age, slope, and pasture vigor index. We then applied the Random Forest regression algorithm to predict and map the cultivated pastures according to their potential for natural regeneration in the 19 Cerrado ecoregions. The potential for natural regeneration was classified into low (< 30% of native plant cover), medium (30-50%), and high (> 50%). Our prediction explained 75% of the data variability. Most of the cultivated pastures presented medium potential for natural regeneration (57%), while 31% and 12% presented high and low potentials, respectively. Cultivated pastures in ecoregions with high mechanization, due to their high water availability and extensive flat terrains, presented low potential for natural regeneration. This first attempt to map the potential for natural regeneration in the cultivated pastures of the Brazilian Cerrado can be used as a proxy for planning low-cost and predictable restoration or environmentally sustainable intensification in this major type of land use found in this biome.

Enhanced Natural Regeneration Potential of Sessile Oak in Northern Hungary: Role of Artificially Increased Density of Insectivorous Birds

Both artificial and natural regeneration of oaks strongly depend on the quantity and quality of the acorn crop, which show high year-to-year variation. The volume of the acorn crop is influenced by many factors including biotic and abiotic effects. The quality (i.e., germination ability, nutrient reserves) of acorns can be decreased by carpophagous insect and fungal pathogen damage or by inadequate weather conditions. Defoliating insects (caterpillars, sawfly larva, etc.) can significantly decrease the acorn crop as well. The most important predators of the defoliators are insectivorous birds during their nesting period. However, in the oak forests of the northern Hungarian mountains, there is a shortage of natural nesting holes. The main aim of our study was to artificially increase the number of the available nesting holes by nest boxes and to maximize the number of breeding insectivorous birds and register the direct (Lepidoptera densities) and indirect (acorn crop quantity and quality) effects of their presence. We found only slight effects on Lepidoptera densities, so we failed to demonstrate a direct effect in the relatively low time frame of our study. But, we could show the indirect positive effect of increased predation on the health state of the acorn crop, resulting in higher seedling densities, which may improve the natural regeneration potential of sessile oak. This result supports the outstanding importance of natural nesting holes in broadleaved forests.

Impacts of human forest management on seed dispersal patterns by scatter-hoarding rodents

Abstract Scatter-hoarding rodents play a central role in seed dispersal, predating and dispersing seeds that affect many plant species’ population dynamics and influence forest regeneration. Anthropogenic changes in forest structure, such as clear-cutting in dense forests, may alter the ecological interactions between seeds and dispersers. This study compared predation and dispersal patterns of holm oak (Quercus ilex L.) acorns by wood mouse (Apodemus sylvaticus L.) in original dense forest [less managed forest (MF)] vs open MF (more MF) in north-eastern Spain. Results showed variations in the patterns of acorn predation and dispersal by wood mouse between forest types. In the MF, a greater fraction of acorns was harvested, and the acorns were being dispersed further than in the original forest. Despite the greater fraction of acorns dispersed in the MF, the proportion of acorns that survived and had the potential to grow was reduced in the MF because of increased predation. This shows that forest management has a significant influence on seed dispersal by rodents and thereby influences the natural regeneration potential of forests.

Natural Regeneration Potential of Tree Flora at Bangabandhu Sheikh Mujib Safari Park (Bsmsp), Dulahazara, Cox’s Bazar, Bangladesh

The aim of this study was to evaluate the natural regeneration status of tree flora at Bangabandhu Sheikh Mujib Safari Park (BSMSP) in Dulahazara, Cox’s Bazar. Six blocks were created within the safari park to explore regeneration potential. A total of 41 sample plots of 5m × 5m size, each centered in the middle of a 20m × 20m vegetation survey plot, was taken. In total, 835 seedlings representing 56 tree species under 29 families were recorded. Euphorbiaceae was the dominant family with 8 species followed by Myrtaceae (6 species) and Combretaceae (4 species). The highest Family Relative Density (FRD) was represented by Myrtaceae (26.95%) followed by Euphorbiaceae (16.05%) and Dipterocarpaceae (12.93%). Euphorbiaceae showed the maximum Family Relative Diversity Index FRDI (14.29%) followed by Myrtaceae (10.71%) and Combretaceae (7.14%). The highest Family Importance Value Index (FIVI) was observed in Myrtaceae (37.66%), whereas Euphorbiaceae and Dipterocarpaceae represented 30.33% and 18.29%, respectively. Species in the order of descending value of Importance Value Index (IVI) were Syzygium fruticosum (24.10), Aporosa wallichii (12.30), Dipterocarpus costatus (12.10), Dipterocarpus alatus (11.60) and Fernandoa adenophylla (11.60). The regeneration percentage of seed-originated individuals was 72%, whereas the rest 28% individuals were from coppices. The onset of safe guard and preserve trees with proper management could contribute conserving native gene pool contribution to ecotourism. J. Biodivers. Conserv. Bioresour. Manag. 2023, 9(1): 1-12

Characterizing the Change of Annual Cone Production in Longleaf Pine Forests

Sporadic cone (or seed) production challenges longleaf pine forest restoration. Characterizing annual cone production change from long-term monitored data provides functional information on the foundational species of this imperiled ecosystem. In this study, permutation entropy (PE) and phase change were used to analyze longleaf pine annual cone production based on cone counts from four sites (Escambia Experimental Forest, Blackwater River State Forest, The Jones Center at Ichauway, and Sandhills State Forest). PE is an analytical tool to measure the complexity of a dynamic system while phase change characterizes the stage of self-organization. Results indicate that PE at each site was close to 1.0 (largely random changes in annual cone production) and generally increased with time. The positive association between the permutation entropy of cone production and average air temperature at different times was significant at two sites (Blackwater River State Forest and The Jones Center at Ichauway). The frequency distribution of phases (e.g., Poor (P), Fair (F), Good (G), Bumper (B)) in cone production followed negative power laws. Phase P could transition to any stage, but more than 50% remained in P across sites. For phase G, it would revert to P more than 50% of the time. Phase B would shift to P, except at Sandhills State Forest. The average lasting time of phase P was approximately 3.7 years. The overall relationship between the interval time of phase B and cone production was not statistically significant. Similarly, the overall relationship between cone production in phase B and the phase change times between consecutive B phases was not statistically significant. These results provide information on the ecological complexity of cone (or seed) production. Our methods can be helpful for estimating the occurrence of bumper cone (or seed) production, the lasting period between phase changes, and providing a tool for predicting natural regeneration potential over time for longleaf pine and other tree species (e.g., masting species).

Natural regeneration potential and dynamics in boreal lichen woodlands of eastern Canada following soil scarification

Boreal lichen woodlands (LWs) are stable low tree-density zones of the Canadian boreal forest whose afforestation has been proposed as a way to create new C sinks and thus mitigate climate change. Planting operations in these remote areas are however costly and time-consuming, and may not be necessary when soil scarification is followed by dense natural regeneration. In the present study, we assessed the natural regeneration potential and dynamics in six boreal LWs of Québec, Canada, 11 years after soil scarification. The number, size (height and stem diameter) and age of seedlings were measured in 2-4 sampling plots per site (18 plots in total). Our data show that scarification operations produced on average 1,400 m2 ha–1 of exposed mineral soil (scarification intensity of 14%) with, however, a large within-site variability. The natural regeneration was mainly composed of black spruce seedlings (&amp;gt; 95%), averaged ∼12,000 seedlings ha–1 across the six sites and significantly varied among sites, mostly due to the variation in scarification intensity. Seedling density averaged ∼9 seedlings m–2 of exposed mineral soil and increased with seed tree mean diameter at breast height (DBH) (R2 = 0.51; P &amp;lt; 0.05) but not with the density of seed trees, revealing the importance of old and large seed trees in natural regeneration success. Together, scarification intensity and the DBH of remaining seed trees explained ∼60% of the variation in natural regeneration density across the 18 sampled plots. The rate of establishment of seedlings was generally high – with on average 60% of the carrying capacity of the substrate being reached within three years following scarification – and increased with seed tree mean DBH (R2 = 0.77; P &amp;lt; 0.05). However, the growth rate of seedlings was very low. Eleven years after scarification, 60% of the seedlings were &amp;lt; 15 cm and the height of 10-yr-old seedlings averaged 27.5 cm. Thus, even though seedling establishment was successful, the biomass accumulated by the natural regeneration was negligible in the span of a decade. Therefore, the implementation of afforestation following scarification appears to be necessary to create significant C sinks in the midterm.

Factors affecting savanna and forest regeneration in pastures across the cerrado

The Cerrado region comprises the world's most biodiverse savanna and the largest cultivated pastures for cattle in Brazil. Forty percent of these pastures are unproductive or degraded, with bare soil and native vegetation increasingly replacing exotic forage grasses. This study sought to investigate the regeneration of native vegetation in the pastures of the Cerrado and to evaluate the contribution of biophysical, land management, and landscape attributes to this process. Across the Cerrado, we analyzed pasture plant communities and the attributes of pasture management intensification, fire events, landscape native vegetation cover, and climate and soil types of 93 active pastures and 15 abandoned pastures. For the abandoned pastures, time since abandonment was an additional variable. On actively cultivated pastures, savanna regeneration varied from 0 to 70%, with a diversity of herbs and woody species. Pasture management was the main predictor of savanna regeneration on cultivated pastures. On abandoned pastures, time since abandonment was the main predictor. Exotic grass cover had a strong negative relationship with savanna regeneration and they were present even in pastures abandoned for 44 years. Our study reveals the potential of natural regeneration of the Cerrado and its particular predictors. The occurrence of pastures with high natural regeneration indicates that national policies can promote native vegetation restoration and silvopastoral systems with predictable, low cost implementation.

Tree sapling vitality and recovery following the unprecedented 2018 drought in central Europe

BackgroundOngoing climate change is anticipated to increase the frequency and intensity of drought events, thereby affecting forest recovery dynamics and elevating tree mortality. The drought of 2018, with its exceptional intensity and duration, had a significant adverse impact on tree species throughout Central Europe. However, our understanding of the resistance to and recovery of young trees from drought stress remains limited. Here, we examined the recovery patterns of native deciduous tree sapling species following the 2018 drought, and explored the impact of soil depth, understory vegetation, and litter cover on this recovery. MethodsA total of 1,149 saplings of seven deciduous tree species were monitored in the understory of old-growth forests in Northern Bavaria, Central Germany. The vitality of the saplings was recorded from 2018 to 2021 on 170 plots. ResultsFagus sylvatica was the most drought-resistant species, followed by Betula pendula, Acer pseudoplatanus, Quercus spp., Corylus avellana, Carpinus betulus, and Sorbus aucuparia. Although the drought conditions persisted one year later, all species recovered significantly from the 2018 drought, albeit with a slight decrease in vitality by 2021. In 2018, the drought exhibited a more pronounced adverse effect on saplings in deciduous forests compared to mixed and coniferous forests. Conversely, sapling recovery in coniferous and mixed forests exceeded that observed in deciduous forests in 2019. The pivotal factors influencing sapling resilience to drought were forest types, soil depth, and understory vegetation, whereas litter and forest canopy cover had a negative impact. ConclusionLong-term responses of tree species to drought can be best discerned through continuous health monitoring. These findings demonstrate the natural regeneration potential of deciduous species in the context of climate change. Selective tree species planting, soil management practices, and promoting understory diversity should be considered when implementing adaptive management strategies to enhance forest resilience to drought events.

Influence of Aspect and Elevational Gradients on The Regeneration of Festuca Macrophylla and Helicrysum Spelindidum Plant Species in Gcca, Central Highlands of Ethiopia

Natural regeneration is an important process that ensures the flow genes and thus preserves the diversity of life in ecosystems. However, natural regeneration is constrained by many factors including biotic, climatic and edaphic factors. The aim of this work was to assess the effects of aspect and elevational gradient on the natural regeneration potential of two competing species in Guassa Community Conservation Area in North Central Ethiopian highlands. We stratified our study area into eight blocks based on aspect and elevational gradient and conducted shrub removal experiment on 160 plots (5m x 5m). From these plots, we conducted vegetation survey following the modified Braun-Blanquette methods every three months. We used two elevational (&lt;3350 m/lower and &gt;3350 m/upper elevation) and four aspect categories (northeast, northwest, southwest and southeast) to compare the seeding density of the target species and species composition studies. On these plots, all vascular plants were recorded and the data was analyzed by two-way ANOVA using SAS statistical software version 9.0.1. In addition, we used LSD test for mean separation test. We computed the similarities in composition, density, abundance and species similarity between soil seedbank and the aboveground vegetation. Results showed that a total of 31 species, representing 27 genera and 16 families were recorded. The families with the highest number of species were Asteraceae (18 species, 22.5%), Fabaceae (3 species, 10%), and Poaceae (3 species, 10%). Of the total families, the dicots constituted 87.5% and monocots 12.5%. Species abundance was negatively correlated with elevation, with fewer species occurring at higher elevation. Meanwhile, species abundance was positively correlated with both northwest and northeast aspect. Treatments done during the study also highly influenced the recovery of vegetation species. High species similarity was also observed between below and aboveground vegetation.

The lower storeys of main tree species in deciduous pioneer tree stands of fertile sites: case of Lithuania

Forest ecosystems face challenges of climate change and the pressure of economic activity on biodiversity. As European policies turn into Green Deal, ecological forestry systems, which aim to increase or at least not reduce biodiversity while maintaining high forest productivity, are becoming particularly relevant. This study examines distribution regularities of the lower storeys of main tree species in fertile not wet habitats of forest communities composed of pioneer deciduous tree species, the understanding of which will allow the development of forestry systems that exploit the natural forest regeneration potential. We used stand-wise forest inventory data on Betula spp., Populus tremula, Alnus incana mature and overmatured stands. We analysed how lower storeys are distributed in the stands of different tree species according to soil conditions, the age, stocking level and mixture. We found that most of stands are not in the second story and understory, from which new stands can be formed. Betula forests have the greatest potential for regeneration, and Alnus incana forests have the lowest one. The most important species of the second story and understory is Picea abies, rarer Fraxinus excelsior and Tilia cordata, other species are more random. With an increasing forest mixture, the second story and understory are found more often. To reduce clear-cutting in the fertile forests of pioneer tree species in forestry, we need to focus on measures to allow the development of lower storeys of the major climax tree species. Keywords: ecological forestry, forest succession, fertile site type, pioneer tree stands, temperate hemiboreal forests.