The Effects Of Climate Warming On Water Characteristics Of Larix Gmelinii

This paper focus on the water relations of Larix gmelinii from different latitudes Tahe,Songling, Heihe, Dailing, which are from north to south. By the measurement of the PV curve,we got eight parameters: the saturate osmotic potential(Ψsat), osmotic potential at incipientplasmolysis (Ψsat),relative water content at incipient plasmolysis (RWC^tlp),osmoticwater volume at incipient plasmolysis (ROWC^tlp),apoplastic water volume (AWC),bulkelastic potential modulus (ε^max),a and b. We also measured the predawn leaf waterpressure(Ψw), soil water content(SWC), water saturation deficit(WSD) and leaf water-losingrate. With analyzing these parameters, we got the seasonal course and differences of the Larixgmelinii in four latitudes. We also measured the background value in the four latitudes inAugust to compare the difference of the same provenance. Last, we compared the drought-resistance of the four latitudes with the integrate evaluation index DI to get the response toclimate warming. The results were as follows:(1) The seasonal courses of the water relations parameters from the PV curve of Larixgmelinii in different latitudes were approximately similar. The drought-resistance was strongerin the early spring (April) and was weaker in the leaf expanding (May), after leaf expanding, itwas more stronger and then kept stable. And it became weaker as leaf falling in October.(2) The drought-resistance was not significantly changed before and after transplanted,except for Dailing and Tahe in the values of RWC^tlp and AWC. Before and after transplanted,the values of RWC^tlp were79.70%, 89.90%, AWC were 53.85%, 72.18% in Dailing, and inTahe were 88.28%, 77.81% and 57.21%, 72.72%. Those indicated that the water-absorptionand water-keep capacity were stronger but the osmotic adjustment capacity was weaker aftertransplanted in those two sites. The value of a was significantly changed before(7.649) andafter transplanted (8.836) in Heihe, which indicated turgot pressure -keeping capacity grewstronger after transplanted.(3) The variation of different provenance was similar in the values ofΨw and WSD. Asthe same water-stress conditions, water-consumption rate was lower in high latitude, andrecovered quickly water status after water-stress. However the difference of predawnΨmaxand dailyΨmin was completely opposite with above results. So drought-resistance wasstronger in Dailing.(4) According the results of leaf water-losing rate: Dailing(46.84%) Heihe(59.09%)Songling(60.01%) Tahe(64.76%), the resistance order to water losing rate from stronger toweaker were: Dailing, Heihe,Songling, Tahe.(5) According the integrate evaluation index DI, the drought-resistance order from stronger to weaker were: (1)Dailing(1.853), Heihe(1.836), Songling(1.819), Tahe(1.715), asleaf expanding in May; (2) Tahe(1.985), Dailing(1.930), Songling(1.914), Heihe(1.865), asgrowing season in July, (3) Dailing(2.031), Songling(1.948), Tahe(1.803), Heihe(1.705), as leaffalling in October.