Relationship between phenology and life form: a test with 25 Patagonian species

Authors

  • R. A. Golluscio,

  • M. Oesterheld,

  • M. R. Aguiar


R. A. Golluscio (golluscio@agro.uba.ar), M. Oesterheld and M. R. Aguiar, Dept de Recursos Naturales y Ambiente, and IFEVA, Fac. de Agronomía, Univ. de Buenos Aires, Av. San Martín 4453, Buenos Aires 1417, Argentina.

Abstract

Soil resource availability varies across seasons and soil layers. Both plant phenology, i.e. the sequence of growth and developmental changes along the year, and plant life form, i.e. the life cycle, distribution of roots, and longevity of leaves, determine the ability to use resources. The phenological heterogeneity within and among life forms of a single community may reveal key features of community structure, such as temporal niche segregation within life forms or convergence of phenological and life form patterns. We described the phenological patterns of most species of a Patagonian steppe composed of four life forms: perennial grasses, shrubs, annual herbs, and perennial herbs. By applying standard multivariate analysis techniques, we classified the species into three phenological groups and analysed the variation among groups and life forms. One phenological group, composed exclusively by grasses, had higher autumn-winter phenological activity than the other two groups. The non-grass groups differed in the date of beginning of vegetative growth and ending of the reproductive growth, one of the groups being earlier than the other. However, the three groups coincided at the phenophase of floral buds and open flowers, which occurred around the time of the maximum rate of phenological change and maximum fraction of photosynthetically active radiation being intercepted by the entire community. Phenological groups and life forms only partially overlapped: grasses and annual herbs belonged to individual phenological groups, whereas shrubs and perennial herbs spread across two groups. Thus, some life forms of the community were strictly related to a phenological behaviour, whereas other showed high temporal niche segregation. Simultaneously, diverse life forms converged into similar phenological patterns.

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