Study On Leaves Phenology In Spring Of Evergreen Broad-Leaved Forest In Tiantong, Zhejiang

Evergreen broad-leaved forests mainly distribute in the subtropical region of China,which has different characteristics with other forests in tropical or temperate areas.Although many research work have been done in subtropical evergreen broad-leaved forests,it just has a few reports concerned the plant phenology in this particular region.In addition,the research about leaves phenology is critical to understand the dynamic change of communities,the development of evergreen broad-leaved forests and the relationship between animals and plants.The leaves phenology mainly change in spring rather than other seasons in evergreen broad-leaved forests.So they choosed the common woody species to reseach 5 phenological phases of leaves in Tiantong,Zhejiang province.They observed the change of the marked plants from buds to leaves in every 3 or 4 days,and this paper discuss the phenology styles,synchronous pattern and dynamic patterns of budburst, leaf emergence,leaf expansion,shoot growth,leaf abscission in spring.Besides,they classify species to 3 styles based on the phenological characters.The paper has 5 main results as below:(1) Most species began to budburst in the last 10 days of March in Tiantong,Zhejiang province,and reached the peak of budburst between the end of March and the beginning of the April.Many species ended the process of budburst in the first 10 days of April.The earlier the species began to budburst,the earlier the species ended the budburst.The peak time of most species that belonge to unimodal pattern is between March 24 and March 30.One of the peak time of many bimodal species is March 27,and the other is April 7.While the species of multi-peaks pattern reached the peak of budburst in different time.Compared between different groups of species,the deciduous species budburst earlier than evergreen species.The canopy trees budburst earlier than shrubs,but the parameters of budburst do not reach marked difference.The dominant species and companion species almost began to budburst at the same time,but the companion species ended budburst is earlier than the dominant species.Based on the budburst synchronous research of 42 kinds of species,the species with high synchrony in budburst probable have unimodal pattern dynamic figures.The budburst curves of species do not have large fluctuate with low synchrony.While the species has medium synchrony,the budburst pattern will probable have two or three peaks in the figures.(2) Most species began to leaf out during the end of March and the begin of April,and got the peaking time at the first 10 days of April.And most species ended the process of leaf emergence at the first and the middle 10 days of April.The earlier the species began to leaf out,the earlier the species ended the process of leaf emergence.The longer the duration time is,the later it ended the process.Leaves phenology was compared for the saplings of different group of species sharing the same microsite.Leaves emergence occurred earlier in the shrubs than the canopy trees.The deciduous trees were earlier than evergreen trees in leaf emergence.The dominant species began to leaf out earlier than the companion species.The time of reaching the peak value of species that belong to unimodal pattern in leaf emergence is at the first 10 days of April,while the peak time of bimodality pattern are the last 10 days of March and the first 10 days of April.The peak time of multi-species is difference with species.According to synchronous research of leaf emergence,the shorter the leaf emergence last,the higer synchronous of the leaf emergence.There is no relevant relationship between leaf emergence and budburst on synchrony(P＞0.1).(3) The beginning time of leaf expansion of most species was during the last 10 days of March,and many species ended the process of leaf expansion at the first 10 days of May.The average duration of leaf expansion is about 34.5 days.The earlier the species expanded leaves,the earlier the species ended the process.Half of the canopy trees leaves is Notophyll,and the other half is Microphyll.Most leaves of the subcanopy trees belong to the Microphyll,and all species of shrubs is the Microphyll.(4) The shoots of many species begin to grow between the last 10 days of March and the first 10 days of April.And ended the process at the last 10 days of April and the first 10 days of May.The longer the shoot grew,the later the shoot ended the process.There is no relationship between the beginning time and the ending time of shoot growth.The shoots and the leaves of the same species almost began to grow at the same time.72%of species belong to styleⅠ,which shoots are earlier finished the process than leaves expansion.The canopy trees belong to styleⅠexcept Cinnamomum camphora.StyleⅠconsist of 45.5%of all shrubs,styleⅡalso consist of 45.5%,and styleⅢconsist of 9.1%of all the species.(5) 10%-40%old leaves defoliate from the shoots in the spring,and the leaf age of defoliation is below 3 old.Different species have different patterns of abscission. The number of younger old leaves is more than that of older leaves in shoots,and the older leaves is easier to defoliate than younger ones.The longer the span of leaves are,the less percentage that 07 old leaves consist of all the defoliation,and the more percentage of 06 old leaves consist.It has no relevant with the percentage of 05 old leaves.