Microhabitats, Germination, and Establishment forMammillaria gaumeri(Cactaceae), a Rare Species from Yucatan

• Published in: International journal of plant sciences 2006-03, Vol.167 (2), p.311-319
• Main Authors: Cervera, J. Carlos, Andrade, José Luis, Simá, J. Luis, Graham, Eric A.
• Format: Article
• Language: English
• Subjects: Ambient temperature; Cactus; Dry seasons; Forest canopy; Germination; Nurses; Plants; Rainy seasons; Seedlings; Soil temperature regimes
• ISSN: 1058-5893; 1537-5315
• DOI: 10.1086/498650

Mammillaria gaumeriis a rare cactus endemic to northern Yucatan that has a low rate of seedling establishment. We evaluated the effect of different light microhabitats on germination and seedling survival for this species in the field. Microclimatic requirements for seed germination are synchronized with those typical of the rainy season: germination was optimal at a soil water potential of −0.2 to 0.0 MPa and at a diurnal/nocturnal temperature of 30°/20°C. Low photon fluxes are necessary for seed germination; maximal germination ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $91.5\% \pm 0.38\% $ \end{document} ) and seedling survival (210 d) occurred in microhabitats receiving 20% of total ambient photosynthetic photon flux density (PPFD). Seedlings growing under this condition had a greater volume/surface area relationship (more water stored within their tissues) than those receiving 50% of total ambient PPFD. Water availability is the limiting factor for seedling establishment in arid and semiarid environments; however, becauseM. gaumeriseedlings had a low tolerance to extreme temperatures, a combination of microclimatic factors determined where a seedling could establish and survive.