Evaluation On The Water Physiological Adaptability Of Tree Species Of Farmland Shelter-belt In Western Of Hei Long Jiang Province

This evaluation chose the main tree species of farmland shelter-belt in western ofHeiLongJiang province, Populus simonyi×P.nigra(18a), Populus alba×P. Beolinensis(17a),Populus alba×P. Beolinensis(3a), Pinus sylvestris L. var. mongolica litv(18a), Pinus sylvestrisL. var. mongolica litv(8a), Larix gmelinii(Rupr.) Rupr(17a). The water physiological parameterwe determined in the field including Natural W.S.D, Critical W.S.D, Natural water requirement,leaf water potential and transpiration rate. Relatively analyzed the water physiologicaladaptability of every species of trees, carried on the drought resistance of every Species of trees.The conclusion were as follow:Populus alba×P. Beolinensis(17a) has a low level in Natural W.S.D and Natural waterrequirement, the numerical value is 14.44% and 26.87%,it also has a high level in CriticalW.S.D, the numerical value is 53.49%, it indicates that degree of water deficit is minor;Populus simonyi×P. nigra(18a) and Pinus sylvestris L. var. mongolica litv(18a) have anoppositional information, the numerical value of Natural W.S.D is 24.87% and 29.05%, thenumerical value of Natural water requirement is 56.06% and 84.70%, the numerical value ofCritical W.S.D is 43.85% and 34.21%, it indicates that degree of water deficit is higher; thelevel of Larix gmelinii(Rupr.) Rupr(17a) is the middle of Populus alba×P. Beolinensis(17a),Populus simonii×P. nigra(18a) and Pinus sylvestris L. var. mongolica litv(18a), the numericalvalue is 16.33%,32.71% and 49.84%. The order of the water physiological adaptability ofevery species of trees is Populus alba×P. Beolinensis(17a)＞Larix gmelinii(Rupr.) Rupr(17a)＞Populus simonyi×P. nigra(18a)＞Pinus sylvestris L. var. mongolica litv(18a).Populus alba×P. Beolinensis(17a) has a low level in the difference PredawdΨw andDailyΨwmin, the numerical value is 2.42MPa; it also has a high level in PredawdΨw andDailyΨwmin, the numerical value is -2.31MPa and -4.73MPa, that indicates its root has astrong capacity in absorbing water, the speed of resuming water is fast, and also has strongcapacity in counteracting disturber; Populus simonyi×P. nigra(18a) and Pinus sylvestris L. var.mongolica litv(18a) have an oppositional information, the numerical value of the differencePredawdΨw and DailyΨwmin is 2.29MPa and 2.50MPa, the numerical value of PredawdΨwis -2.88MPa and -2.63MPa, the numerical value of the DailyΨwmin is -5.18MPa and -5.13MPa, that indicates they has weak capacity in counteracting disturber; the level of Larixgmelinii(Rupr.) Rupr(17a) is the middle of Populus alba×P. Beolinensis(17a), Populussimonii×P. nigra(18a) and Pinus sylvestris L. var. mongolica litv(18a), the numerical value is2.83MPa,-2.02MPa and -4.85MPa. The order of the water physiological adaptability of everyspecies of trees is Populus alba×P. Beolinensis(17a)＞Larix gmelinii(Rupr.) Rupr(17a)＞Popul -us simonyi×P. nigra(18a)＞Pinus sylvestris L. var. mongolica litv(18a).The transpiration rate of broadleaf species of trees is greater than needle species of trees, theorder of transpiration rate is Populus alba×P. Beolinensis(17a)＞Larix gmelinii(Rupr.)Rupr(17a)＞Populus simonyi×P.nigra(18a)＞Pinus sylvestris L. var. mongolica litv(18a).Themean value of transpiration rate is 0.371 g.g^-1.h^-1, 0.290 g.g^-1.h^-1, 0.220 g.g^-1.h^-1 and 0.062 g.g^-1.h^-1. It indicates that Populus alba×P. Beolinensis(17a) and Populus simonyi×P.nigra(18a)have strong capacity in latency water consumption, the water consumption of unit areagreater, Larix gmeIinii(Rupr.) Rupr(17a) and Pinus sylvestris L. var. mongolica litv(18a) havean oppositional information. Populus alba×P. Beolinensis(17a), Larix gmeIinii(Rupr.)Rupr(17a) and Populus simonyi×P. nigra(18a) have larger ratio between the mean value oftranspiration rate of July and August and the mean value of transpiration rate June andSeptember, the ratio is 2.06, 2.35 and 2.43, it indicates that this three species of trees have agreater amplitude of transpiration strength between the month with more rainfall and the monthwith less rainfall, and also indicates the transpiration get strong inhibition in the month withless rainfall, they get through the dry season with reducing the transpiration water consumption,this characteristic can make them living well in the month with less rainfall; Pinus sylvestris L.var. mongolica litv(18a) have an oppositional information, the ratio is 1.86, that indicates it hasweak inhibition in dry season.All of the indexes of the Populus alba×P. Beolinensis(3a), were similar with the Populusalba×P. Beolinensis(17a), so it shows the PopuIus alba×P. Beolinensis(3a) also have a lowlevel in drought stress, a high level in water physiological adaptability and have strong droughtresistance. All of the indexes of Pinus sylvestris L. var. mongolica litv(8a),was in the middlebetween this tree species, the in water physio-ecological adaptability and drought resistancewas stronger than Pinus sylvestris L var. mongolica litv(18a).