Reyes & Griffiths 2009 (Separate Publ.) Mexico

Ecophysiological Studies of perennials of the Bromeliaceae family In a dry forest: strategies for survival

Author(s):—C. Reyes G. & H. Griffiths in A Tribute to Park S. Nobel

Publication:— (2009).

Abstract:—Seasonally dry tropical forests constitute environments that can have a shift in the dominant life forms during the year. These forests are defined as being frost free, having an annual rainfall of 250 to 2000 mm and several months of drought (Mooney et al. 1995). Seasonal forests have a lower species diversity than moist forests, but a higher structural (plant habit) and physiological diversity (Medina 1995). The forest of Chamela, Mexico, represents one of the most diverse seasonally dry tropical forests (Lott 1993) and is one of the most seasonal regarding precipitation (Bullock 1986). During the 8 months of dry season at Chamela, the landscape appears dominated by families that exhibit Crassulacean acid metabolism (CAM), a metabolism that conserves water by performing gas exchange at night. Only a few C3 shrubs remain active, while more than 95 % of the trees shed their leaves (Bullock and Solís-Magallanes 1990; Martínez- Yrízar and Sarukhán 1990). Out of the 950 plant species present at Chamela, 60 exhibit CAM photosynthesis. These perennials are found in four families: Agavaceae (four species), Bromeliaceae (26 species), Cactaceae (19 species) and Orquidaceae (11 species). At the driest upland site, the Bromeliaceae family is represented by three terrestrial and ten epiphytic species; the epiphytes all belonging to the Tillandsioideae sub-family (Reyes-García et al. 2008), the most drought resistant (Pittendrigh 1948). In this chapter we will explore strategies of the perennial plants in the family Bromeliaceae to survive and thrive during the prolonged drought by reviewing previous studies using stable isotopes and other ecophysiological tools. Even though the physiology of these plants has been well documented and specific microclimatic requirements for different species have been described, few attempts have been made to develop a niche theory among coexisting species. This leaves the open question on whether the distribution of the species in the habitats responds only to the history and dispersion of the species. Yet, because niche theory has been well developed in dry and seasonal desert communities, which can have great resemblance with the canopy microenvironment; we will compare those case studies and theories of water use strategies to those observed in the Bromeliaceae community of Chamela.

Pages: 121–151