本地和外来草本物种对水分条件时间异质性的可塑响应

In recent years, many studies have shown that extreme climate events occur morefrequently. The extreme climate led to frequent drought and inundation events, which affected thegrowth of both exotic and native plants. In order to discuss the strategies of exotic and nativeplants in adapting to temporal heterogeneity in water conditions by investigating their responses tothe sequence of drought and inundation events, four native and four exotic perennial herbaceousspecies in western Montana, USA were used as study objects. All plants were treated withmoderate water (CK), initial inundation before drought (I-D) and initial drought before inundation(D-I) conditions, and variations in a series of morphological and biomass traits were measured.The results were as follows: (1) Compared with CK, both D-I and I-D treatments significantlyreduced the total biomass of exotic species (P < 0.05). (2) D-I treatment significantly reduced thetotal biomass at the early stage, and late belowground biomass and root: shoot ratio of nativespecies, but significantly improved their later relative growth (P < 0.05). (3) D-I treatmentsignificantly reduced the scaling exponent of the allometric relationship between belowground andaboveground biomass for all plants, with a higher allometric exponent for exotic species thannative species (P < 0.05). In conclusion, the sequence of extreme events (inundation and drought)could alter the allocation of biomass between exotic and native plants. Early drought was morelikely to reduce the accumulation of plant biomass than late drought, but it could promote thegrowth of native species in late period. The total biomass of native species was not reduced underenvironmental stress, indicating that native species had a strong ability to maintain phenotypic stability. Distribution patterns of aboveground and belowground biomass relationships weredifferent between native and exotic species under D-I treatment.