Wednesday, August 8, 2007

PS 43-64: Phenology of shrubs and precipitation pulses in the Chilean semiarid zone

María Moreno-Chacón, Universidad de La Serena, Julio R. Gutierrez, Universidad de Chile, Peter L. Meserve, Northern Illinois University, and Douglas A. Kelt, University of California.

We assessed the effect of precipitation pulses on the phenology of three dominant shrub species (Porlieria chilensis, Adesmia bedwellii, Proustia cuneifolia), with dimorphic root systems but with different foliar pattern, in north-central Chile. We hypothesized that the plant response to a rain event will be faster in P. chilensis (perennial leaves) than in A. bedwellii (semi-deciduous leaves) and P. cuneifolia (deciduous leaves), although the latter species will show higher growth activity.

The study was carried out in Parque Nacional Bosque Fray Jorge, north-central Chile from 2003 through 2005. Rainfall was 80, 168, and 90 mm in 2003, 2004, and 2005, respectively. The three shrub species showed inter-annual variation in the onset and length of the vegetative and reproductive phases. Phenological activity in P. chilensis initiated soon after the onset of winter rains, while in A. bedwelli and P. cuneifolia this occurred one and two months later than in P. chilensis, respectively. For P. chilensis the vegetative phase peaked in July (2003) and November (2005), but in 2004 (rainy year) the vegetative phase remained high for three months. The length of the reproductive phase was variable among years but always ended in December. In A. bedwellii there was large overlap between phenological phases which lasted from June (winter) until December (early summer). Similar to P. chilensis, phenological phases in A. bedwellii were longer in 2004. In P. cunneifolia phenological activity extended from July-August (winter) until the end of summer season (February-March). The vegetative phase in P. cuneifolia peaked between October and November, while the reproductive phase peaked in the summer season between January and March.


[DK1]I thought 2004 was the rainy year. Did I misunderstand?

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