Regeneration Dynamics Research Articles

Vegetation Pattern and Regeneration Dynamics of the Progressively Declining Monotheca buxifolia Forests in Pakistan: Implications for Conservation

Monotheca buxifolia (Falc.) A. DC., a wild edible fruit-yielding tree species, has economic and ecological importance, yet there is a lack of studies concerning its distribution pattern and regeneration dynamics at a larger-scale. This study aims to produce the first country-level classification of Monotheca forests based on their unique floristic composition and influential abiotic factors, besides their natural regeneration dynamics, across the environmentally diverse landscapes in Pakistan. For this purpose, floristic inventory was carried out in 440 plots where environmental variables, stand dendrometric characteristics and woody-species regeneration were recorded. During this survey, 3789 individuals of 27 woody tree species belonging to 25 genera and 22 families were sampled. These native and exotic tree species were mostly dicot (73%) with predominately mega-phanerophytic (88%) lifeforms, which largely reflect strong chorological differentiation and distinct linkage (55%) to the Sino-Japanese phytogeographical region. M. buxifolia and co-occurring species exhibiting similar environmental affinities were grouped into four ecologically distinct communities by Ward’s cluster analysis. Ordinations further highlight the special effects of topographic and edaphic factors besides anthropogenic interference on the sampled plots. Generally, Monotheca stands were moderately dense, with the average density varying considerably, ranging from 296 to 325 individuals/ha, with basal area ranging from 41.26 to 93.35 m2 ha−1. In the understory stratum, natural regeneration of Monotheca was mostly scant and mainly covered by Dodonaea shrubs. Size class structure of the dominant species shows pronounced effect of anthropogenic intervention as reflected by the presence of fewer individuals of juveniles and larger trees. Overall, the cut stump frequency was higher at juvenile and mature stages, which may be attributed to over-harvesting and extraction of fuelwood apart from the adverse effect of climate change in the region. We concluded that both topographic and edaphic factors coupled with biotic interventions are more influential in the distribution and persistence of M. buxifolia and co-occurring woody species and might be considered in its restoration and conservation. Thus, we recommend an urgent management plan to favor Monotheca regeneration for allowing the renewal of these rapidly declining remnant stands in Pakistan.

Dynamics of tropical forest regeneration in the Mexican Mesoamerican Biological Corridor from 2000 to 2020: does forest regeneration maintain continuous forest cover?

Dynamics of tropical forest regeneration in the Mexican Mesoamerican Biological Corridor from 2000 to 2020: does forest regeneration maintain continuous forest cover?

Assessment of natural population and regeneration dynamics of Pinus gerardiana in dry temperate region of north western Himalaya

Assessment of natural population and regeneration dynamics of Pinus gerardiana in dry temperate region of north western Himalaya

Dynamics of stump sprout regeneration after transformation to multiaged management in coast redwood forests

There is considerable interest in multiaged management as a silvicultural and restoration tool in redwood forests of California. For multiaged silviculture to be successful, a new cohort of trees must first be able to regenerate underneath the residual overstory. We used annual re-measurement data from a replicated manipulative experiment in coastal northern California to determine how understory light, stand density, and spatial arrangement of residual trees affected coast redwood (Sequoia sempervirens) and tanoak (Notholithocarpus densiflorus) stump sprouts regenerating after partial harvest of conifers and felling-to-waste of tanoak. Four treatments (group selection, aggregated retention, low-density dispersed retention, and high-density dispersed retention) were applied at each replicate on redwood-dominated sites. Height growth of redwood sprouts was 49% greater than tanoak sprouts across all treatments. Redwood and tanoak sprouts were sensitive to overstory density. Redwood sprouts were marginally taller under high-density aggregated versus dispersed overstory trees at the same residual stand density (39.5 m2/ha BA). Sprout growth correlated with understory light; redwood sprouts exhibited a significant increase in sensitivity to light availability from year 2 to year 6. No differences in redwood sprout growth were detected when retaining a residual tree on the same root system versus sprouts growing on a root system where all redwood stems were cut. Our finding that cutting unwanted hardwoods in tandem with partial harvesting of merchantable conifers can maintain a competitive advantage for redwood sprouts versus tanoaks is an important consideration for maintaining redwood dominance when transitioning to multiaged management.

Exploring Ecoacoustic Trajectories in a Giant Sequoia Forest After Wildfire

Forest management strategies that create spatially diverse fire-caused disturbance outcomes, consistent with historic fire regimes, are a desired condition for fire adapted western United States forests. In this context, the temporal dynamics of forest response to fire can inform the tempo and scale of forest management, including prescribed burning. Here, we investigated the use of ecoacoustic methods to assess ecological condition in a four-year period (2016–2019) after wildfire in a giant sequoia forest landscape within Kings Canyon National Park, California, United States. Audio recorders at nine sites were deployed soon after the 2015 Rough Fire subsided. The monitoring sites were located in regions with different fire histories, representing five fire history categories. We used the Acoustic Complexity Index (ACI) to document biotic chorus complexity. This previously tested ecoacoustic index provided a daily indicator of biotic sound activity in frequencies dominated by avian calls. Patterns in ACI were evaluated using generalized additive mixed models to understand the relationship with time-since-fire and covariates that accounted for season, fire history category, and weather conditions. We showed that time-since fire and fire-history influenced patterns in ACI after accounting for season and air temperature effects. Monitoring sites where prescribed fire preceded the Rough Fire showed the highest predicted ACI and evidence for a relatively consistent seasonal pattern in ecoacoustic activity across subsequent seasons. Sites without prescribed fire and burned by the Rough Fire exhibited the most pronounced successive decreases in ACI in the first and second years after the fire. The daily temporal resolution of the ecoacoustic index also revealed phenological shifts related to time-since-fire and fire history. Sites unburned by the Rough Fire offered some context for how fire changed ecoacoustic activity post-wildfire, however evidence suggested they were also impacted by the presence of the nearby Rough Fire. The patterns in the ecoacoustic index when combined with vegetation surveys offered complementary insights into ecological dynamics of regeneration after fire. Our exploratory analysis showed that using ecoacoustic methods in wildfire monitoring offers a scalable approach to remote sensing of ecological trends. Archived recordings from the monitoring effort afford future opportunities for new or more detailed insights.

Dynamics of the Natural Regeneration of Vegetation in an Anthropized Forest in Côte d’Ivoire, West Africa

Ivorian classified forests have been highly anthropized by cocoa farming. In an attempt to provide guidance to the government on approaches to the restoration of the forest while respecting the aspirations of local populations, permanent plots were set up in the classified forest of Haut-Sassandra, and were monitored and measured for 3 years. This study was intended to analyze the evolution of the vegetation of permanent plots in the classified forest of Haut-Sassandra from 2018 to 2021. The results show that the vegetation evolves with the cessation of some agricultural activities. These plantations are colonized by pioneer species during the first three years of the abandonment of agricultural activities. Mortality rates increased by 477.59% and recruitment rates were reduced by 61.87% in regularly maintained plantations compared to their condition three years ago. However, the plantations with no agricultural activities and those which were not maintained but harvested had the highest recruitment rates of pioneer and heliophilous individuals. In sum, tree species could recolonize the classified forest of Haut-Sassandra if clearing is prohibited in cocoa farms. However, the populations could continue to harvest the pods from the cocoa trees which are already established in the classified forest of Haut-Sassandra.

Modelling drivers of Atlantic Forest dynamics using geographically weighted regression

Despite its ecological importance and anthropogenic pressures, only a few studies have modeled deforestation and regeneration dynamics within Brazil’s Atlantic Forest biome. In this article, we propose an econometric approach to model these landscape dynamics. Based on public available data, the model was first processed using a STEPWISE procedure in the software SPSS Statistics, with ad hoc selection of the most relevant model. Next, we used Geoda software to account for spatial dependence and compared its results to a geographically weighted regression executed in ArcGIS software using a 25-municipality neighborhood distance. The amount of forest remnants, percentage of private protected land, expansion of pastures and planted forests can significantly explained the dynamics of deforestation and regeneration in the Atlantic Forest. The geographically weighted regression improved the model adjustment, and also illustrated localities where model performance was not satisfactory, and demonstrated where variables were more or less significant. The model can be used to inform conservation policies. It can also be used to create scenarios for simulations, allowing assessment of how possible market and policy changes, such as cattle rising and reforestation suffering market pressures, and changes in the national Forestry Code, would impact future deforestation and regeneration rates.

Initial oak regeneration responses to experimental warming along microclimatic and macroclimatic gradients.

Quercus spp. are one of the most important tree genera in temperate deciduous forests in terms of biodiversity, economic and cultural perspectives. However, natural regeneration of oaks, depending on specific environmental conditions, is still not sufficiently understood. Oak regeneration dynamics are impacted by climate change, but these climate impacts will depend on local forest management and light and temperature conditions. Here, we studied germination, survival and seedling performance (i.e. aboveground biomass, height, root collar diameter and specific leaf area) of four oak species (Q. cerris, Q. ilex, Q. robur and Q. petraea). Acorns were sown across a wide latitudinal gradient, from Italy to Sweden, and across several microclimatic gradients located within and beyond the species' natural ranges. Microclimatic gradients were applied in terms of forest structure, distance to the forest edge and experimental warming. We found strong interactions between species and latitude, as well as between microclimate and latitude or species. The species thus reacted differently to local and regional changes in light and temperature ; in southern regions the temperate Q. robur and Q. petraea performed best in plots with a complex structure, whereas the Mediterranean Q. ilex and Q. cerris performed better in simply structured forests with a reduced microclimatic buffering capacity. The experimental warming treatment only enhanced height and aboveground biomass of Mediterranean species. Our results show that local microclimatic gradients play a key role in the initial stages of oak regeneration; however, one needs to consider the species-specific responses to forest structure and the macroclimatic context.

Excited-state properties of newly sensitized imidazole-arylamine-based organic DSSC sensitizers in solvent and adsorbed on TiO2/FTO support

Six recently synthesized arylamine-imidazole combo dyes, utilized in dye-sensitized solar cells staining TiO2 semiconductor, were spectroscopically investigated. Studies were performed with application of steady-state and time-resolved absorption spectroscopies and were done on dyes dissolved in dichloromethane and anchored on TiO2/FTO film support. The investigations allowed to characterize the excited state decay dynamics of individual compounds, determine time constants of dye-to-TiO2 electron injection process for dyes adsorbed on TiO2/FTO support and subsequent recombination and dye regeneration dynamics. These studies were performed on bare dye/TiO2/FTO photoanodes in air environment and, if possible, on the same samples with dye layer immersed in electrolyte solution. These evaluations allowed to determine approximate time constants for dye regeneration and directed toward dye that reveals most advantageous properties and hypothetically should outperform its counterparts as TiO2 sensitizer.

Impacts of oak-focused silvicultural treatments on the regeneration layer nine years posttreatment in a productive mixed-oak southern Appalachian forest

Oaks (Quercus spp.) are foundational species in forests and woodlands in the eastern USA. An oak regeneration bottleneck has occurred throughout its range in recent decades, and refining silvicultural treatments to localized conditions has become a focus in addressing this problem. This study was developed to determine species regeneration dynamics among oak and oak competitors on productive sites in response to silvicultural treatments in oak-dominated southern Appalachian mountain forests. The treatments were: an oak shelterwood treatment (25–30% basal area [BA]) reduction through midstory removal with herbicides); a prescribed fire treatment (two, late-dormant season prescribed fires occurring over a 9-yr period); a shelterwood and burn treatment (one, late-dormant season prescribed fire 3–5 yr following 30–40% BA removal); and an unmanaged control. To determine treatment impacts on the regeneration layer, changes in relative and absolute importance values and stems ha-1 (germinants up to stems ≤ 4.9 cm diameter at breast height [DBH]) were calculated at the species group and individual species level 0 and 9 yr postinitial treatment. The greatest relative increases in importance values were 1,401% and 2,995% for the red oak group and yellow-poplar (Liriodendron tulipifera), respectively, in the shelterwood and burn (SWB). Changes in all species groups were predominantly influenced by the smallest size-class (< 0.6 m tall), with the exception of northern red oak (Q. rubra) and yellow-poplar in the SWB. The SWB significantly reduced importance values of all shade-tolerant species groups and was the only treatment to decrease red maple (Acer rubrum) importance value and density over the study duration. The prescribed fire (RXF) treatment increased the red oak group importance value, while simultaneously decreasing yellow-poplar's importance value and increasing red maple's importance value. Changes in the red oak group in the SWB and the RXF were driven by northern red oak. Treatments did not significantly change the importance value of the white oak group. The SWB was the only treatment to significantly decrease overstory BA. The RXF and SWB treatments improved the competitive status of only some oak species, but modifications to these treatments might result in better control of yellow-poplar and red maple competition, further improving oak's competitive status. Although the SWB resulted in modest recruitment of northern red oak saplings, all treatments appear in need of additional follow-up vegetation control to further improve the competitiveness and recruitment of oak into large size-classes.

Climate and ungulate browsing impair regeneration dynamics in spruce-fir-beech forests in the French Alps

Key messageDifferent components of water balance and temperature reduce density and height growth of saplings of Picea abies (L.) H. Karst (Norway spruce), Abies alba Mill. (silver fir) and Fagus sylvatica L. (European beech) in mixed uneven-aged forests in the French Alps and Jura mountains. Ungulate browsing is an additional pressure on fir and beech that could jeopardise the renewal of these species in the future.ContextThe uncertainty in tree recruitment rates raises questions about the factors affecting regeneration processes in forests. Factors such as climate, light, competition and ungulate browsing pressure may play an important role in determining regeneration, forest structures and thus future forest composition.AimsThe objective of this study was to quantify sapling densities and height increments of spruce, fir and beech and to identify dominant environmental variables influencing them in mixed uneven-aged forests in the French Alps and Jura mountains.MethodsSapling height increment and density were recorded in 152 plots, and non-linear mixed models were obtained to establish relations between them and environmental factors known to affect regeneration, namely altitude, slope, aspect, canopy openness, soil characteristics, temperature, precipitation and ungulate browsing.ResultsRegeneration density, varying from 0 to 7 saplings per m 2, decreased with sapling height and was also negatively affected for spruce by PET, but positively for fir by precipitation and for beech by mean annual soil water content. Height increment reached up to 50 cm annually, increasing with sapling height and canopy openness and decreasing under high maximum summer temperatures for spruce and beech. The statistical effect of different environmental variables varied slightly among species but trends were quite similar. Additionally, ungulate browsing was high, with fir being the most intensely browsed, followed closely by beech, while spruce was rarely browsed.ConclusionsAll these results suggest that more temperature warming and a decrease in water availability could negatively impact sapling growth and density in the three species, with possible reduction of forest renewal fluxes. The observed increase of ungulate populations leading to increased browsing could be particularly detrimental to fir saplings.

Northern hardwood regeneration dynamics 10 years after irregular shelterwood and mechanical control of understory American beech

In northern hardwood stands of the northeastern USA and southeastern Canada, the abundance and occurrence of American beech (Fagus grandifolia Ehrh) regeneration have increased substantially over the past decades, to the detriment of other deciduous species such as sugar maple (Acer saccharum Marshall) and yellow birch (Betula alleghaniensis Britton). To promote the regeneration of these declining species, we established an experimental study near Québec City (Quebec, Canada) to compare the effects of various partial cutting treatments and mechanical control of understory American beech. The design comprises 4 randomized complete blocks, each containing an uncut control, a hybrid single-tree and group selection cutting (SC), two intensities of continuous cover irregular shelterwood (CCIS) and an extended irregular shelterwood (EIS). American beech regeneration, which dominated the sapling layer before cutting, was removed with brush saws in gaps created in the SC and CCIS treatments as well as in the entire understory of the EIS treatment. In addition, gaps and the EIS understory were scarified to favor yellow birch regeneration, and 12 exclosures were built to prevent cervid browsing in CCIS gaps and in entire understory of the EIS treatment. Ten years after cutting, yellow birch regeneration was more abundant in gaps and in the EIS treatment than in the uncut control. These results confirm that increasing the understory light level, eliminating American beech saplings and scarifying the soil can successfully favor yellow birch establishment. However, preferential browsing of yellow birch outside exclosures maintained the overall dominance of American beech in the long term. Thus, under these conditions, damage from repetitive browsing outweighed the positive effects of actions aimed at promoting the regeneration of yellow birch. In the end, despite abundant seed availability, sugar maple remained only a minor component of the regeneration.

Ecological indicators of passive restoration in South Brazil's Atlantic Forest areas with former Pinus taeda L. plantations

The use of suitable ecological indicators for assessing and monitoring passive restoration is essential to understand the dynamics of natural regeneration and the restoration course. However, most developed restoration protocols in Brazil are specifically intended for monitoring active restoration. Only a few studies are addressing ecological indicators for passive restoration. In this context, we tested indicators defined by a monitoring protocol (SMA Resolution 32/2014) formulated for active restoration, along with other indicators of richness, diversity, and functional aspects of natural regeneration. The evaluations took place in sites under passive restoration in different age classes (between three and twelve years old) and in a secondary riparian forest (reference ecosystem) inside the Mixed Ombrophilous Forest (Araucaria Forest) in South Brazil. Those sites had previously been covered and degraded by Pinus taeda L. plantations. We compared the evaluated sites with the intermediate and final reference values proposed by the protocol to define the suitability of the tested indicators and the forest restoration process. Results showed that the canopy cover, density, and richness of regenerants are suitable to evaluate areas under passive restoration with a history of degradation by forestry. However, it is necessary to adapt the protocol's reference values. We further suggest the inclusion of other indicators related to the ecosystem's structure and functionality as the herbaceous cover, dispersion syndrome, life form, and the ecological group of species, as well the definition of indicator species for the different restoration levels. Despite the low similarity in composition, structure, and functional aspects with the reference ecosystem, the passive restoration showed potential to perpetuate the successional course in the studied areas.

The dynamics of cell death patterns and regeneration during acute liver injury in mice.

Acute liver injury is a serious clinical syndrome with multiple causes and unclear pathological process. Here, CCl4‐ and D‐galactosamine/lipopolysaccharide (D‐gal/LPS)‐induced acute liver injury was established to explore the cell death patterns and determine whether or not liver regeneration occurred. In CCl4‐induced hepatic injury, three phases, including the early, progressive, and recovery phase, were considered based on alterations of serum transaminases and liver morphology. Moreover, in this model, cytokines exhibited double‐peak fluctuations; apoptosis and pyroptosis persisted throughout all phases; autophagy occurred in the early and the progressive phases; and sufficient and timely hepatocyte regeneration was observed only during the recovery phase. All of these phenomena contribute to mild liver injury and subsequent regeneration. Strikingly, only the early and progressive phases were observed in the D‐gal/LPS model. Slight pyroptosis occurred in the early phase but diminished in the progressive phase, while apoptosis, reduced autophagy, and slight but subsequently diminished regeneration occurred only during the progressive phase, accompanied by a strong cytokine storm, resulting in severe liver injury with high mortality. Taken together, our work reveals variable modes and dynamics of cell death and regeneration, which lead to different consequences for mild and severe acute liver injury, providing a helpful reference for clinical therapy and prognosis.

Age, growth, longevity, and post-fire/thinning response of chinkapin oak seedlings in a Kansas upland hardwood forest1

Thinning and prescribed fire are often used to promote oak recruitment into the canopy; however, little is known about the longevity of resprouting oak seedlings and how age affects growth response to these treatments. We investigated this by excavating 180 chinkapin oak seedlings (Quercus muehlenbergii) from an eastern Kansas upland hardwood forest study area divided into different combinations of burning and thinning treatments: control, burn only, burn and thin to 7 m2/ha, burn and thin to 14 m2/ha, thin to 7 m2/ha, and thin to 14 m2/ha. In each treatment, approximately three years post-treatment, we aged the seedlings at the root collar (“root age”) and the base of the current aboveground shoot using tissue staining and microscopy techniques. Annual shoot growth rate was calculated for each individual based on the age of the shoot and its total height. We compared these shoot growth rates in height across treatments and investigated this relationship as a function of plant age using the root age. The oldest root age was 48 yr, and 20% of the roots were ≥ 18 yr. Mean root age of advance reproduction was 11.8 years, while mean age of associated aboveground stems was 4.1 yr, with the oldest age structure belonging to treatments without any burn with the control being the oldest. The majority (90%) of the mismatch between root and shoot age was associated with burn treatments. Root age had a strong positive correlation with shoot growth rate in the burn + thinning treatments and also the untreated control, suggesting that age becomes an influence on growth when resprouting under adequate light conditions but also when individuals experience low competition. Further determination of root age structures, such as along gradients of site productivity, would likely aid in further understanding regeneration dynamics and management for sustaining oaks.

Single-cell transcriptome analysis reveals three sequential phases of gene expression during zebrafish sensory hair cell regeneration.

Loss of sensory hair cells (HCs) in the mammalian inner ear leads to permanent hearing and vestibular defects, whereas loss of HCs in zebrafish results in their regeneration. We used single-cell RNA sequencing (scRNA-seq) to characterize the transcriptional dynamics of HC regeneration in zebrafish at unprecedented spatiotemporal resolution. We uncovered three sequentially activated modules: first, an injury/inflammatory response and downregulation of progenitor cell maintenance genes within minutes after HC loss; second, the transient activation of regeneration-specific genes; and third, a robust re-activation of developmental gene programs, including HC specification, cell-cycle activation, ribosome biogenesis, and a metabolic switch to oxidative phosphorylation. The results are relevant not only for our understanding of HC regeneration and how we might be able to trigger it in mammals but also for regenerative processes in general. The data are searchable and publicly accessible via a web-based interface.

Overcoming the regeneration barriers of tropical dry forest: effects of water stress and herbivory on seedling performance and allocation of key tree species for restoration

AbstractTropical dry forests (TDF) are one of the most threatened and poorly protected ecosystems in the Americas. Although there are international efforts for the restoration of TDF, how stress factors such as herbivory or water limitation due to changes in precipitation, impact the regeneration dynamics of these forests is poorly understood. Specifically, how seedlings of key tree species for TDF restoration cope with current abiotic pressures such as the intensification of climatic events, and biotic factors like herbivory, is not yet fully understood. Here, we compared seedling performance, and allocation of biomass, and water to roots vs. shoots for three legume, and one non-legume TDF tree species, as a response to water limitation and herbivory in an 8-month greenhouse experiment. Contrary to our expectations, we found that the non-legume species, G. ulmifolia, had the best performance compared to legumes, while N-fixing and non-fixing legumes showed similar performance. Based on our findings, we suggest the use of G. ulmifolia in TDF restoration projects due to its high performance despite abiotic and biotic stress factors, its allocation of biomass and water to belowground structures. We also recommend the use of N-fixing legume species owing to their ability to fix nitrogen, which guarantees an N input to the soil, important in the first stages of succession. However, the legume species used in this experiment do not appear to resist the abiotic and biotic stressors studied. Thus, more studies exploring the response of dry forest plant species to stress factors are key for informing and assuring more effective TDF restoration efforts.

Do trait responses to simulated browsing in Quercus robur saplings affect their attractiveness to Capreolus capreolus the following year?

With the rise of large herbivore populations in most northern hemisphere forests, browsing is becoming an increasingly important driver of forest regeneration dynamics. Among other processes affecting the regeneration, the concept of plant-herbivore feedback loops holds that browsed saplings are more subject to subsequent herbivory. This phenomenon is interpreted as a consequence of compensatory growth following browsing since fast growth is generally associated with higher digestibility and lower defense against herbivores. However, studies linking browsing-induced trait variations to subsequent attractiveness to herbivores are still lacking, especially in the forest context. In this study, we experimentally examine the existence of a feedback loop between oak ( Quercus robur L.) and roe deer ( Capreolus capreolus ) and investigate its underlying morphological and chemical traits. We simulated single and repeated roe deer browsing on nursery-grown oak saplings and measured the changes in sapling height growth, lateral branching, leaf traits and winter shoot traits over two years. We conducted winter feeding trials with tame roe deer one year after the first treatment to test the effect of simulated browsing on sapling attractiveness. Simulated browsing reduced sapling height growth but had no effect on branching. Simulated browsing had no effect on leaf traits after half a year, but decreased the phenolic content and increased the fiber content of winter shoots the following winter. Contrary to our predictions, roe deer preferentially browsed control saplings over saplings previously browsed. After two years, repeated browsing promoted fast carbon acquisition leaf traits (high chlorophyll, high specific leaf area and low fiber content), reduced leaf phenolic content and increased leaf digestibility. We showed that a reduction in 1-year-old oak sapling height growth following browsing, combined with increased structural defense at the expense of chemical defense in winter shoots the following winter, was correlated with reduced browsing pressure, thereby challenging the feedback loop hypothesis. However, we also demonstrated that repeated browsing promoted fast carbon acquisition leaf traits in 2.5-year-old saplings, which tend to support the existence of a feedback loop on older and more intensively browsed saplings. As such, our study provides empirical evidence that morphological and physiological trait responses to browsing influence oak sapling attractiveness, but that the direction and magnitude of this effect depend on the ontogenic stage of the sapling and on the number of browsing events. • We examine the morphological and chemical response of oak saplings to browsing. • Browsing reduces sapling height growth and modifies shoots chemical composition. • We show with feeding trials that roe deer prefers unbrowsed saplings. • Oak trait responses to browsing decrease the probability of subsequent herbivory.

Reconstruction of regulatory network predicts transcription factors driving the dynamics of zebrafish heart regeneration

The limited regenerative capacity in mammals has serious implications for cardiac tissue damage. Meanwhile, zebrafish has a high regenerative capacity, but the regulation of the heart healing process has yet to be elucidated. The dynamic nature of cardiac regeneration requires consideration of the inherent temporal dimension of this process. Here, we conducted a systematic review to find genes that define the regenerative cell state of the zebrafish heart. We then performed an in silico temporal gene regulatory network analysis using transcriptomic data from the zebrafish heart regenerative process obtained from databases. In this analysis, the genes found in the systematic review were used to represent the final cell state of the transition process from a non-regenerative cell state to a regenerative state. We found 135 transcription factors driving the cellular state transition process during zebrafish cardiac regeneration, including Hand2, Nkx2.5, Tbx20, Fosl1, Fosb, Junb, Vdr, Wt1, and Tcf21 previously reported for playing a key role in tissue regeneration. Furthermore, we demonstrate that most regulators are activated in the first days post-injury, indicating that the transition from a non-regenerative to a regenerative state occurs promptly.

GDNF neurotrophic factor signalling determines the fate of dermal fibroblasts in wound-induced hair neogenesis and skin regeneration.

We propose that GDNF, a glial cell line‐derived neurotrophic factor, can promote hair follicle neogenesis and skin regeneration after wounding by directing the fate of dermal fibroblasts. Our hypothesis is largely based on detailed GDNF and receptor analysis during skin regenerative stages, as well as the induction of GDNF receptors after wounding between the pro‐regenerative spiny mouse (genus Acomys) and its less‐regenerative descendant, the house mouse (Mus musculus). To characterize the GDNF‐target cells, we will conduct a series of lineage‐tracing experiments in conjunction with single‐cell RNA and assay for transposase‐accessible chromatin sequencing experiments. The heterogenetic dynamics of skin regeneration have yet to be fully defined, and this research will help to advance the fields of regenerative medicine and biology. Finally, we believe that stimulating the GDNF signalling pathway in fibroblasts from less‐regenerative animals, such as humans, will promote skin regeneration, morphogenesis and scarless wound healing.