两种山黄麻属植物在近一世纪里气孔密度和潜在水分利用率的变化

统计了狭叶山黄麻(Trema angustifolia BL．)和光叶山黄麻(Trema cannabina Lour)腊叶标本在近一世纪里的气孔密度，并利用叶中δ13C值推算了它们在这段时期的潜在水分利用率。结果表明，从20世纪20年代到90年代，狭叶山黄麻和光叶山黄麻的气孔密度分别降低28.1％和40.0％；潜在水分利用率分别增加19.5％和42.2％。相关分析表明，在这70年里，两种植物的气孔密度与大气CO2浓度成显著负相关，而它们的潜在水分利用率与大气CO2浓度成显著正相关。

CHANGES IN STOMATAL DENSITY AND INTRINSIC WATER USE EFFICIENCY OF TWO TREMA SPECIES OVER THE LAST CENTURY

The stomatal densities of herbarium specimens of Trema angustifolia BL. and T. cannabina Lour were investigated ,and the intrinsic water use efficiency of both species was computed from δ13C values in their leaves. From 1920 to 1990,the stomatal densities of T. angustifolia and T. cannabina reduced by 28 % and 40% respectively, while their intrinsic water use efficiency increased by 20% and 42% respectively. Changes in these parameters with time (and therefore with increasing of atmospheric CO2 concentration)were significant in both species :with stomatal densities declining and water use efficiency increasing with time.