The Evaluation On Characteristics Of Drought Resistance And Adaptability Of Main Trees In Rocky Desertification District Of GuiZhou Province

Taking tree species for vegetation in Stone Dissertation District of Huangguoshu in Guizhou as study object, in the view of physiological ecology, this paper deeply studied the characteristics of water consumption, photosynthesis and water physiological ecology and growth of the main tree species through potted plant trial and plantation survey, and the comprehensive evolution of drought tolerance and the main reason of restricting Pn were done using membership function and regression equation and provide theoretical ad practical base for ecological forestation in Stone Dissertation District. The main conclusions were below:1,Drought tolerance of the main tree species for forestationWith increase in days of the drought treatment , water consumption by transpiration, water potential of soil (WS) and water potential of plant (WP) decreased lineally, power function correlation between WP and WS, but speed and extent of decrease was different among tree species. According to the mathematical relationship between WP and WS, systematical classification method was applied to divide 19 kings of tree species into four sorts: a drought tolerance of dehydration postponement with high tissue water potential, including Pinus massoniana Lamb. and Nerrium indicum Mill.; a drought tolerance of sub-dehydration postponement with high tissue water potential, including Dodonaea viscosa (Linn.) Jacq., Elaeocarpus decipiens Hemsl., Melia azedarach L., Sapium sebiferum (Linn.) Roxb., Toona sinensis (A. Juss.) Roem., Tapiscia sinensis Olivx., Cinnamonum camphora L., Michelia szechuanica Dandy., Ligustrum vicaryi Mill., Platycladus orientalis (Linn.) Franco., and Koelreuteria paniculata Laxm.; a drought tolerance of dehydration tolerance with low tissue water potential, including Camptotheca acuminata Decne.; a drought tolerance of sub-dehydration tolerance with low tissue water potential, including Elaeocarpus decipiens Hemsl., Ligustrun lucidum Ait., Zanthoxylum bungeanum Maxim., Catalpa fargesii Bur. f. duclouxii (Dode) Gilmour, and Fokienia hodginsii (Dunn) Henry et Thomas.With increase in days of the drought treatment, photosynthesis (Pn) decreased linearly, stomatal conductance (Gs) decreased exponentially, transpiration rated (Tr) decreased linearly and power, while water use efficiency (WUE) increased in initial stages then decreased. This indicated that Tr reacted sensitively to drought stress in initial stages due to stomatal close, while the decrease extent of Pn was larger than that of Tr because of the increase in non stomatal restriction.Under drought stress, with the decrease in WP, Pn deceased logarithmically, Tr and Gs decreased exponentially. There was a significant difference among tree species. BecauseNerrium indicum Mill.belonged to a classic drought tolerance of dehydration postponement with high tissue water potential, stress extent of Nerrium indicum Mill. did not judge by WP.Linear and power function correlation between Pn and Gs, power function correlation between Tr and Gs, linear correlation between Pn and Tr. With the Tr and Gs decrease, there was different in extent of Pn among tree species. The same extent of decrease in Tr, Pn of Ligustrun lucidum Ait. and Osmanthus fragrans Lours. decreased largest, and Pn of Tapiscia sinensis Olivx. smallest.PSII electronic transmit rate (Fm/Fo), potential activity and photosynthesis efficiency were restrained by drought stress, chlorophyll content of partial tree species decreased notably. There was significant different in root amount, root and shoot biomass, growth amount among tested tree species.Under middle-drought stress, the capability of drought tolerance and water control from strong to feeble: Elaeocarpus decipiens Hemsl., Cinnamonum camphora L., Sapium sebiferum (Linn.) Roxb., Dodonaea viscosa (Linn.) Jacq., Catalpa fargesii Bur. f. duclouxii (Dode) Gilmour, Ligustrum vicaryi Mill., Pinus massoniana Lamb., Melia azedarach L., Toona sinensis (A. Juss.) Roem., Camptotheca acuminata Decne., Osmanthus fragrans Lours., Platycladus orientalis (Linn.) Franco., Fokienia hodginsii (Dunn) Henry et Thomas., Ligustrun lucidum Ait., Tapiscia sinensis Olivx., Michelia szechuanica Dandy., Zanthoxylum bungeanum Maxim. And Koelreuteria paniculata Laxm.; Under heavy-drought stress, the capability of drought tolerance and water control from strong to feeble: Toona sinensis (A. Juss.) Roem., Cinnamonum camphora L., Elaeocarpus decipiens Hemsl., Catalpa fargesii Bur. f. duclouxii (Dode) Gilmour, Tapiscia sinensis Olivx., Michelia szechuanica Dandy., Melia azedarach L., Ligustrum vicaryi Mill., Pinus massoniana Lamb., Camptotheca acuminata Decne., Dodonaea viscosa (Linn.) Jacq., Sapium sebiferum (Linn.) Roxb., Fokienia hodginsii (Dunn) Henry et Thomas., Koelreuteria paniculata Laxm., Platycladus orientalis (Linn.) Franco., Ligustrun lucidum Ait. and Zanthoxylum bungeanum Maxim.2,Photosynthetic and water ecophysiology adaptation mechanism of main tree species for vegetation restoration There were notable difference in SWC and Ws among AS/SP, those of northern slope was higher than southern slope. Under drought stress, the peak time of Gs, Pn and WUE moved up and presentation of"sleep at noon"was the adaptation mechanism of tree to drought.Daily average values of WP, WUE and Pn in northern slope were higher than those in southern slope, on the contrary, daily average values of Tr and Fv/Fm in southern slope were higher than those in northern slope; daily average values of WP and Tr on the higher SP were higher than on the lower SP. The difference of WP resulting from AS was related to SW, and the higher WP on the higher SP related to stronger water uptake capability and smaller water consumption by Tr. And, the AS effect on the daily average value of WUE and Pn arose mainly from the difference in daily average value of WP.The tested tree species were divided into four sort in terms of different parameters using hierarchical clustering method, high, sub-high, sub-low and low, respectively. As followed: Platycladus orientalis (Linn.) Franco., high WUE, sub-high Pn, sub-low WUE and Fv/Fm; Cinnamonum camphora L., high Pn and Tr, sub-low WUE and Fv/Fm; Ligustrum quihoui Carr., high Fv/Fm, sub-high Pn and Tr, sub-low WUE; Ligustrun lucidum Ait., high Tr, sub-low Pn, low Fv/Fm and WUE; Fokienia hodginsii (Dunn) Henry et Thomas., sub-high WUE and Pn, sub-low Fv/Fm and Tr; Nerrium indicum Mill., sub-high WUE and Fv/Fm, low Pn and Tr; Sapium sebiferum (Linn.) Roxb., sub-high WUE, sub-low Fv/Fm and Pn, low Tr; Sophora viciifolia Hance. and Pyracantha fortuneana (Maxim.) Li., sub-low WUE, Pn, Fv/Fm and Tr; Dodonaea viscosa (Linn.) Jacq., sub-low WUE and Fv/Fm, low Pn and Tr; Ligustrum vicaryi Mill., sub-low WUE and Fv/Fm, sub-high Pn and Tr.Under drought season, WUE affected mainly by Tr; with the increase in Gs and Tr, the restriction of Pn increase was related to drought stress. There was positive correlation between Pn and Gs, WUE, Tr. WP become a main reason only in 5 equation, which indicated these plant subjected from great drought stress.There were significant difference in growth amount, biomass and root amount of tested tree species among AS/SP.