Differences of carbon and nitrogen stoichiometry between different habitats in two natural Korean pine forests in Northeast China's mountainous areas

There is a strong link between vegetation and environmental factors.Therefore,to elucidate how the stoichiometric characteristics of plants respond to different habitats,we studied organic carbon(C)and total nitrogen(N)stoichiometry characteristics of plants in four different habitats of two different natural Korean pine forests.Three of the habitats(gaps,mounds,and pits)were formed via tree uprooting,whereas an undisturbed site(closed canopies)was used as a control.The followings were our main findings:(1)the organic carbon content of more than half of the 12 picked plants showed significant differences in different habitats.Most of the plants in pit-mound complexes exhibited lower organic carbon contents than plants in gaps and closed canopies;(2)there was no significant differences in the total nitrogen content in 13 of the 25 groups of plant samples;(3)interestingly,the C/N of the sample groups with significant differences in total nitrogen also showed significant differences;(4)there was no significant variations in the stoichiometric characteristics of plants that grew in gaps;however,the variations among plants that grew in pits and mounds were significant;(5)through redundancy analysis(RDA),we find that the main factors effecting the C and N stoichiometric characters of the plants were plants own regulation and the change of photosynthetically active radiation(PAR).In conclusion,the C and N stoichiometric characteristics of plants did not respond to gap formations,but they did strongly respond to pit-mound complex formations.Photosynthetically active radiation was the most important effective factor to plants in the four habitats.