Wellington A B
Department of Botany, Monash University, 3168, Clayton, Vic., Australia.
Oecologia. 1984 Nov;64(3):360-362. doi: 10.1007/BF00379133.
Comparisons of predawn leaf water potential were made between adults, seedlings and coppicing lignotubers of yellow mallee, Eucalyptus incrassata Labill., during a period of severe drought between December 1981 and March 1983. Measurements were made on plants from areas which were one year, four years, and more than twenty years unburnt.Seedlings and coppice regrowth from sites burnt one year previously had significantly higher leaf water potentials than plants from older sites. Little change in water status of long-established plants occurred, despite the drought. There was no difference in the water potentials of plants from sites which were more than four years unburnt. Seedlings of both the one year old and four year old cohorts suffered mortality rates of more than 50% during the summer season towards the end of the drought when leaf water potentials had decreased to -4 MPa.It is suggested that the difference in plant water status, observed between sites which were one year unburnt and older sites, was due to a temporary cessation of the depletion of soil moisture reserves by the vegetation. Fire results in complete defoliation of established vegetation and it is some years before community evapotranspiration returns to pre-fire levels.
1981年12月至1983年3月的严重干旱期间，对厚皮桉（Eucalyptus incrassata Labill.）的成年植株、幼苗和萌生木质块茎进行了黎明前叶水势的比较。对来自未燃烧一年、四年和二十多年的地区的植株进行了测量。与来自较老地区的植株相比，一年前燃烧过的地点的幼苗和萌生再生植株的叶水势显著更高。尽管干旱，长期生长的植株的水分状况变化不大。未燃烧超过四年的地区的植株的水势没有差异。在干旱接近尾声的夏季，当叶水势降至-4 MPa时，一岁和四岁龄组的幼苗死亡率均超过50%。有人认为，在未燃烧一年的地点和较老地点之间观察到的植物水分状况差异，是由于植被暂时停止了对土壤水分储备的消耗。火灾导致成熟植被完全落叶，群落蒸散量需要数年才能恢复到火灾前的水平。
