Tree ecophysiology in the context of climate change

Forest structure and function strongly depend on and concurrently influence environmental conditions.Tree performance is generally governed by its genetics and environment;thus,recent hotspots in this field include tree genotype×environment,phenotype×environment,and functional trait×environment interactions.The editorial,review,and 22 original research articles in this Special Issue,"Tree ecophysiology in the context of climate change",highlight ecophysiological phenomena(e.g.,climate hormesis,seed germination,tree mortality),processes(e.g.,tree metabolism,photosynthate allocation,nutrient uptake and transport),indicators(e.g.,carbon sequestration,pollutants),measurements(e.g.,thermal time methods,soil quality indices,vegetation spectral index,and near-infrared leaf reflectance),and modeling(e.g.,climate correlations with tree growth,photo synthetic phenology,hydraulic strategies,OliveCan model)in the context of global climate change.Understanding forest-environment interactions from an ecophysiological perspective as climate changes provides insights into species fitness in suboptimal environments,species competition for limited resources,and phylogenetic divergence or convergence of species,and predicting species distributions.

Variation and stability analysis of growth traits of poplar clones in the seedling stage in northeast China

Plant phenotypes are infl uenced by genetic and environmental factors.In this study,the growth traits of 43 one-year-old poplar clones grown at diff erent sites in northeast China(Dongling State-owned Forest Protection Center,DL;Baicheng State-owned forest farm,BC;and Cuohai Forest farm,CH)were evaluated and analyzed across clones and sites.Results show signifi cant diff erences in height and base diameter among sites and clones.Phenotypic and genetic variation coeffi cients ranged from 49.59%(BC)to 58.39%(DL)and from 49.33%(BC)to 58.06%(DL),respectively.Additive main eff ects and multiplicative interaction(AMMI)analysis showed that the eff ects of genotype,environment,and genotype×environment interaction were signifi cantly diff erent.Genetic variation was the main source of variation,accounting for 48.6%.AMMI biplot showed that clone 30 had high and stable yields at the three sites.From an evaluation of multiple traits and GGE biplot that clone 2,clone 30 and clone 25 had higher yield than the other clones at DL,CH and BC,respectively.These clones will provide material for forest regeneration in northeast China.

Conical Sonic-Supersonic Solutions for the 3-D Steady Full Euler Equations

This paper concerns the sonic-supersonic structures of the transonic crossflow generated by the steady supersonic flow past an infinite cone of arbitrary cross section.Under the conical assumption,the three-dimensional(3-D)steady Euler equations can be projected onto the unit sphere and the state of fluid can be characterized by the polar and azimuthal angles.Given a segment smooth curve as a conical-sonic line in the polar-azimuthal angle plane,we construct a classical conical-supersonic solution near the curve under some reasonable assumptions.To overcome the difficulty caused by the parabolic degeneracy,we apply the characteristic decomposition technique to transform the Euler equations into a new degenerate hyperbolic system in a partial hodograph plane.The singular terms are isolated from the highly nonlinear complicated system and then can be handled successfully.We establish a smooth local solution to the new system in a suitable weighted metric space and then express the solution in terms of the original variables.

Designing near-natural planting patterns for plantation forests in China

Background: China has a long tradition of managing planted forests. Different species of Populus, Eucalyptus, Larix, Cunninghamia and Pinus are planted to satisfy the local demand for wood products and provide ecological services at the same time. Evidence of the greater resilience of natural forests provides the motivation to develop asymmetric planting patterns, which is the focus of this study. We present a new method for designing plantation patterns that follow those observed in natural ecosystems and to maintain some regularity for operational convenience. Methods: Based on the uniform angle index, we analyzed the spatial structure of six natural forests in different regions of China. The uniform angle index describes the degree of spatial uniformity of the n nearest neighbors of a given reference tree. Accordingly, we identified all possible patterns of a neighborhood group within a regular planting pattern and developed a method to optimize planting point arrangements that contain some randomness as well as a minimum degree of regularity. Results:(1) There are 13 types of structural units in a regular planting, including seven random units, five even units and one cluster unit;(2) Five near-natural arrangements are presented with a minimum proportion of 50% of random units. These five arrangements represent a combination of regularity for operational convenience and asymmetry. Conclusions: The new planting patterns developed in this study are expected to increase the asymmetric competition and resilience of these important ecosystems. Some experimental plantings, based on our findings, have already been established, e.g., in Pinus tabulaeformis plantations in Tianshui, Gansu Province, and in a Populus deltoides plantation in Fangshan near Beijing.

Gender difference in network relationship between inter-temporal decisions and prefrontal activation levels in internet gaming disorder

Background:Impulsivity and decision-making are key factors in addiction.However,little is known about how gender and time sensitivity affect impulsivity in internet gaming disorder(IGD).Objective:To investigate the gender difference of impulsive decision-making and relevant brain responses in IGD.Methods:We conducted a functional magnetic resonance imaging(fMRI)study with 123 participants,including 59 IGD individuals(26 females)and 64 matched recreational game users(RGUs,23 females).Participants performed a delay-discounting task during fMRI scanning.We examined gender-by-group effects on behavioral and neural measures to explore the preference for immediate over delayed rewards and the associated brain activity.We also investigated the network correlations between addiction severity and behavioral and neural measures,and analyzed the mediating role of brain activity in the link between delay discounting parameters and IGD severity.Results:We found significant gender-by-group interactions.The imaging results revealed gender-by-group interactions in the dor-solateral prefrontal cortex,medial frontal gyrus,and inferior frontal gyrus(IFG).Post hoc analysis indicated that,for females,RGUs showed higher activity than IGD individuals in these brain regions,while for males IGD individuals exhibited higher activity than RGUs.The activation in the left IFG mediated the relation between Internet Addiction Test score and discount rate in females.In males,the activation in the right dlPFC mediated the relation between IAT score and time sensitivity.Discussion:Our findings imply that male IGD participants demonstrate impaired intertemporal decisions associated with neural dysfunction.Influencing factors for impulsive decision-making in IGD diverge between males(time sensitivity)and females(discount rate).These findings augment our comprehension of the neural underpinnings of gender differences in IGD and bear significant implications for devising effective intervention strategies for treating people with IGD.