Modifying regeneration strategies classification to enhance the understanding of dominant species growth in fire-prone forest in Southwest China

Background:In fire-prone ecosystems,plant species having different post-fire regeneration strategies(PFRS)coexist at the local scale while showing different growth dynamics.To evaluate the effect of PFRS on species regeneration,we investigated the plant communities burned in different years in the central Yunnan Province,Southwest China.Several indicators describing plant growth and population importance were measured to compare the regeneration of four dominant tree species,including one facultative seeders(FS)and three obligate resprouters(OR).Partial correlation and mixed linear effect modeling were applied to disentangle the contribution of intrinsic and environmental factors to the interspecific variation in post-fire regeneration.Results:We identified two subtypes of plant growth strategy in the early post-fire stage for OR species;i.e.,number growth(ORþN)priority and height growth(ORþH)priority for sprouting stems.Generally,the FS and OR species varied in height growth rate with different temporal dynamics.The ORþN species occupied post-fire space horizontally with more resprouts and larger coverage than ORþH and FS species at the earlier stage.In contrast,the ORþH species generally had far less resprouts per clump,more variations in stem height and basal diameter.Factor analysis showed that the variation of post-fire plant regeneration was not effectively explained by environmental factors(R2<20%);however,the linear mixed models with the modified PFRS as a random effect substantially increased the explanation.Conclusions:The differentiated regeneration dynamics and growth priorities in the four dominant tree species indicated a critical dichotomy of habitat occupation strategy for the resprouter species during the early stage of post-fire forest restoration.Our study uncovered a trade-off between height versus number growth priority in the post-fire tree growth strategy and provides a novel perspective in understanding the living space occupying(niche partitioning)process and species coexistence in post-fire forest community assembly.

Clinical strategies to enhance nerve regeneration

The slow rate of nerve regeneration after injury or recon- struction remains a clinical problem because it prohibits the timely reinnervation of distant target muscles be- fore the irreversible degeneration of the neuromuscular junction and breakdown of muscle tissue. As such, high （proximal） nerve injuries result in the incomplete recovery of motor function and poor functional outcomes despite current and timely surgical management. Experimentally, several strategies have been shown to enhance nerve regen- eration and improve functional recovery in animal models but translation to clinical practice has not been realized. Two potential treatments, tacrolimus （immunosuppres- sant） and electrical stimulation are commonly used for other reconstructive indications and as such, are both read- ily available clinically. There is some evidence, which will be reviewed in subsequent sections, that these approaches may also be useful in enhancing neuronal regeneration.

Beyond taxol: microtubule-based strategies for promoting nerve regeneration after injury

After injury, damaged axons have the capacity to regenerate, but the regenerative capacity of the axon, particularly axons of the central nervous system, is quite limited. This is because the damaged axons tend to retract, because they encounter obstacles such as scar tissue and inhibitory molecules, and because their growth rates simply do not match those of a juvenile axon. In recent years, there has been a focus on microtubules as among the most important factors in encouraging injured adult axons to regenerate. Microtubules are hollow polymeric filaments composed of tubulin subunits that provide structural support for the axon.

Tree mortality and regeneration of Euphrates poplar riparian forests along the Tarim River,Northwest China

Background:Tree mortality and regeneration(seedling and sapling recruitment)are essential components of forest dynamics in arid regions,especially where subjected to serious eco-hydrological problems.In recent decades,the mortality of the Euphrates poplar(Populus euphratica)along the Tarim River in Northwest China has increased.However,few studies have quantified the causes of mortality and regeneration in this azonal riparian forest type.Methods:The present study describes the annual hydrological response of tree mortality and regeneration in forest gaps.A total of 60 canopy gaps were investigated in six replicate grid plots(50m×50 m)and the annual runoff and water consumption data during the period of 1955–2016 were collected from hydrological stations in the middle reaches of the Tarim River.We compared the regeneration density of seedlings and saplings within the canopy gap areas(CGAs),undercanopy areas(UCAs),and uncovered riverbank areas(RBAs)through detailed field investigation.Results:Our study found that the mortality of young and middle-aged gap makers has increased remarkably over recent decades,particularly since the year 1996.The main results indicated that regional water scarcity was the primary limiting factor for long-term changes in tree mortality,as shown by a significant correlation between the diameter at breast height(DBH)of dead trees and the annual surface water.The average density(or regeneration rate)of seedlings and saplings was highest in the RBAs,intermediate in the CGAs,and lowest in the UCAs.Compared with the UCAs,the CGAs promote tree regeneration to some extent by providing favorable conditions for the survival and growth of seedlings and saplings,which would otherwise be suppressed in the understory.Furthermore,although the density of seedlings and saplings in the CGAs was not as high as in the RBAs,the survival rate was higher in the CGAs than in the RBAs.Conclusion:Forest canopy gaps in floodplain areas can play a decisive role in the long-term germination and regeneration of plant species.However,as a typical phreatophyte in this hyper-arid region,the ecosystem structure,functions and services of this fragile P.euphratica floodplain forests are threatened by a continuous decrease of water resources,due to excessive water use for agricultural irrigation,which has resulted in a severe reduction of intact poplar forests.Furthermore,the survival of seedlings and saplings is influenced by light availability and soil water at the regional scale.Our findings suggest that policymakers may need to reconsider the restoration and regeneration measures implemented in riparian P.euphratica forests to improve flood water efficiency and create canopy gaps.Our results provide with valuable reference information for the conservation and sustainable development of floodplain forest ecosystems.

ROCK inhibition as a novel potential strategy for axonal regeneration in optic neuropathies

Optic neuropathies or optic nerve diseases are a frequent cause of permanent vision loss that can occur after inflammation,ischemia,infection,tumors,trauma and/or an elevated pressure inside the eye（also called intraocular pressure or IOP）.