| Landscape plant configuration is an important part of landscape design and greening.Scientific,effective and reasonable landscape plant configuration needs to consider the growth habits,niche and habitat needs of different species,which requires us to study the distribution pattern and causes of landscape plants in natural communities and original habitats.In fact,species distribution patterns are one of the core topics in community ecology.Recently,much progress has been made on species distribution patterns when inferred from plant functional traits.However,functional traits are only approximations of physiological processes,and even when patterns are identified,physiological mechanisms underlying species distribution patterns may still be elusive.Lower subtropical evergreen broad-leaved forests are the zonal vegetation at the subtropical area.Seasonal and even abnormal drought frequently occur in this type of forests,suggesting that this forest has a high potential for studying the effects of functional traits and hydraulic physiology and their linkage on species distribution.Therefore,in this study,by focusing on the 20-ha lower subtropical evergreen broad-leaved forest plot at Dinghu Mountain in Guangdong Province,I combined plant functional traits and hydraulic physiology to infer community assembly mechanisms.My research started with plant functional traits(plant morphology)and hydraulic measures(water transport capacity and drought tolerance),and then was focused on how plant functional traits,hydraulic physiology and their linkage influence the distribution patterns of 85 woody species with DBH ≥ 1 cm within the plot.I also evaluated how well the functional trait approach predicts the actual physiological measurements.This study was conducted with the aims to provide theoretical foundations for biodiversity maintenance and species coexistence in subtropical forests,and to provide information to predict how tree species will respond to changes in global precipitation patterns.Moreover,the results can provide theoretical basis and practical guidance for landscape plant configuration.The main results are as follows:1.Relationship between plant functional traits and community species distribution patterns in the subtropical evergreen broad-leaved forestPlant functional traits can well characterize the distribution pattern of tree species,and the correlation between different optimal habitat factors and functional traits was different.Moreover,functional traits have a good ability to predict the distribution patterns of tree species.Specific leaf area(SLA)can predict the tree distribution patterns at the level of soil nutrients(PC1),maximum tree height(Hmax)can predict the distribution pattern at the levels of altitude,aspect of slope,and soil variables PC1(soil nutrient)and PC2(soil moisture and available potassium).Net photosynthetic rate per unit leaf area(Aarea)can predict the distribution patterns at the levels of soil PC2.The leaf P content per unit dry weight(Pmass)has the most powerful prediction ability for the distribution patters along altitude and convexity.2.Relationship between hydraulic physiology and community species distribution patterns in the subtropical evergreen broad-leaved forestThe hydraulic physiological parameters that characterize water transport capacity,including sapwood specific conductivity(Ks)and/or leaf specific conductivity(Kl),Huber value(HV)and drought resistance parameter(water potential at turgor loss point,Tlp)can predict the distribution patterns of tree species at the levels of altitude and concavity.P50,with lower value representing stronger cavitation resistance,can predict the species distribution along the aspect of slope,while the species with lower HV tend to distribute at the habitats with higher PC2,i.e.,the habitats with lower soil water and available potassium content.3.Linkage between functional traits and hydraulic physiology and its relationship with community species distribution patternsPlant functional traits and hydraulic physiological processes could well characterize the species distribution patterns.Multiple stepwise regression models were used to analyze the effects of plant functional traits and hydraulic physiological processes on species distribution patterns.It was found that functional traits were more effective in predicting species distribution patterns.Only Tlp can predict the distribution of species along the altitudinal level.The distribution pattern of other levels is mostly related to functional traits.Especially,the P content per plant leaf dry weight can predict the distribution pattern of tree species at altitude and concavity level.The maximum tree height can predict the species distribution pattern in other levels except the convexity and the slope degree.The functional traits and hydraulic physiological processes could not effectively predict the species distribution patterns at the level of the slope.When linking functional traits to hydraulic pysiological processes,their assocations can jointly predict the tress species distribution patterns at the level of altitude.The prediction of the actual physiological process by plant morphology(plant functional traits)is evaluated from the perspective of plant physiological process.The results showed that except P50,other hydraulic physiological characteristics can be predicted by plant functional traits.Drought resistance(Tlp)is mainly predicted by leaf water content and N/P ratio,water transport capacity(Kl and Ks)is mainly predicted by wood density(WD)and net photosynthetic rate per unit leaf area(Aarea),and HV is predicted by LA,LDMC,Nmass and Pmass.In summary,plant functional traits and hydraulic physiological processes could well characterize tree species distribution patterns in the lower subtropical evergreen broad-leaved forest,and functional traits were more effective in predicting tree species distribution patterns.In the plant functional traits,Pmass and the maximum tree height,followed by SLA and Aarea can strongly predict species distribution patterns.In the hydraulic physiological parameters,except for P50,water transport capacity(Ks and Kl),HV and drought resistance factor(Tlp)can be predicting the distribution pattern of tree species in the elevation and convexity levels.In addition,all the hydraulic variables but P50 could be effectively predicted by plant functional traits. |
PDF Full Text Request