A New Classification for Plant Phenology Based on Flowering Patterns in Lowland Tropical Rain Forest Trees at La Selva, Costa Rica

A new classification and conceptual framework for plant phenology are proposed to resolve problems in describing tropical patterns. A long-term (12 yr) survey of flowering in 254 lowland tropical rain forest trees of 173 species from the La Selva Biological Station in Costa Rica showed highly diverse, irregular, and complex patterns. Analysis of this survey data relied primarily on graphical analyses that provide data representation methods rather than numerical summaries that provide data reduction methods. The classification differs from previous ones in three ways. It uses, as the primary criterion, frequency of the time series, based on explicit time and amplitude scales, so that irregular temporal sequences are revealed. It features a system of subsidiary classes based on other quantitative descriptors: regularity, duration, amplitude, date, and synchrony. Finally, the conceptual framework separates patterns at each level of analysis so that adding the time series at one level produces a time series for the next higher level. Levels are hierarchical from the flower to the individual, population, and community with additional non-nested levels such as the guild. The four basic classes-continual, subannual, annual, and supra-annual--are applied to patterns at any level of analysis. The classification system provides a logical framework for quantitative description of phenological behavior leading to more standardized comparisons. Thus we can see that tropical phenology differs from temperate phenology in two major ways. In tropical species, the nature of the pattern may change from one level of analysis to the next, which is not typical of temperate species. In many tropical species, phenological patterns vary more widely over the geographic range of a species than they do in temperate species.