Stem Respiration Spatial-temporal Dynamics And Characteristics Of Sapwood/heartwood Of Larix Gmelinii

There were 8 provenance(Mangui,Genhe,Xinlin,Tahe,Hebei,Sanzhan,Zhongyangzhan and Wuyiling) Larix gmelinii in this study as the research object.We used the Li-6400 system to measure the stem respiration(Rw) and its controlling factors of 8 provenance Larix gmelinii. At the same time,the increment core method was applied to measure the growth characteristics of sapwood and heartwood.The Ln(Rw)of all 8 provenance at the three height(10cm above ground surface,DBH and the middle of the stem) was significantly correlated to the stem surface temperature and the correlation degree was depending on the height and the provenance.The stem surface temperature explained 68%～86%,66%～84%and 45%-82% variations in stem respiration.The seasonality of stem surface temperature and stem respiration in the different height and provenance showed a bell-shape pattern with different maximums. There was no general pattern for the temperature sensitivity coefficient of stem respiration of 8 provenance Larix gmelinii(GZ＞DBH＞D10).Compared with the stem respiration,the variations and temperature sensitivity coefficient of the maintenance respiration were less significant There were significant differences in annual fluxes of maintenance and growth respiration.The contribution of maintenance respiration and growth respiration range 64.06～96.86.%and 3.13～35.93%,respectively.There were significant differences in such growth parameters as diameter at breast height(DBH),sapwood width(SW),sapwood area (SA),heartwood radius(HR) and mean sapwood growth rate(MSGR) among the provenances. The mean values of the parameters from the most southern provenance - Heibei were the greatest,whereas those from Sanzhan were the least.Provenances also significantly influenced the relationships between SA,heartwood area(HA) and MSGR,however,it did not affect the allomteric relationships of the parameters against DBH and the ratio of heartwood area to sapwood area(HSR).The SW,HR,HSR and SGR were significantly correlated to DBH;and SA and HA were related to DBH as a power function.The mean annual air temperature and precipitation of the origins significantly affected the SA and MSGR of the larch trees except for the Sanzhan provenance.We concluded that significant changes in the growth characteristics of sapwood and heartwood of L.gmelinii due to the long-term adaptation to changes in temperature and precipitation of the origin,which were presented in terms of changes in growth rates instead of growth patterns.