Vegetation classification requires the defining of a hierarchy of types based on a spatial and temporal dimensionality. Spatial variation is achieved by plots being placed across the landscape; however, temporal dimensionality is generally only inferred but not directly tested and is rarely incorporated within the circumscription of types. Here, 108 permanent plots are surveyed across 7 years within the Mulga Lands Bioregion of north-western New South Wales through a drought cycle to assist in incorporating temporal dimensionality within community definition. Herbaceous biomass and species density decreased significantly and species composition changed associated with increasing drought conditions, with a return to closer to original conditions by the end of the study. Here, nine temporal associations and 31 synusiae are defined. The changes noted have significant implications for current vegetation classification methods, benchmarking and threatened community listings. The use of permanent plots in vegetation classification is recommended at least for threatened communities and highly dynamic vegetation types associated with less predictable climates.

植被分类需要基于空间和时间维度来定义类型层次。空间变化是通过在景观上放置地块来实现的；然而，时间维度通常只是推断出来的，而不是直接测试的，并且很少包含在类型的范围内。在这里，通过干旱周期对新南威尔士州西北部 Mulga Lands Bioregion 内的 108 个永久地块进行了 7 年的调查，以帮助将时间维度纳入社区定义。草本生物量和物种密度显着下降，物种组成随着干旱条件的增加而发生变化，在研究结束时恢复到更接近原始条件。在这里，定义了 9 个时间关联和 31 个 synusiae。注意到的变化对当前的植被分类方法、基准和受威胁社区名录具有重大影响。建议在植被分类中使用永久地块，至少对于受威胁的社区和与不太可预测的气候相关的高度动态的植被类型。