Seed germination, seedling growth and habitat partitioning in two morphotypes of the tropical pioneer tree Trema micrantha in a seasonal forest in Panama

Abstract

Abstract:We examined the distribution, germination, growth and photosynthetic characteristics of two co-existing morphotypes of the pioneer tree Trema micrantha at the Barro Colorado Nature Monument (BCNM), Panama. Morphotypes differed significantly in distribution and in seed characteristics. A 'large'-seeded morphotype (endocarp mass = 3.83 mg) was associated with treefall gaps in the forest interior, whereas a 'small'-seeded morphotype (endocarp mass = 1.38 mg) was found predominantly on landslides on the margins of Lake Gatun. Seeds of the small-seeded morphotype germinated faster than seeds of the large-seeded morphotype, with seedlings of the small-seeded morphotype showing both a higher Unit Leaf Rate (ULR) and a lower Specific Leaf Area (SLA). Differences in photosynthetic rates reflected differences in SLA; the small-seeded morphotype had a higher rate on a leaf area basis, while the large-seeded morphotype had a higher rate on a leaf mass basis. Although allocation patterns between morphotypes varied in a way consistent with known interspecific differences between 'sun' and 'shade' plants, relative growth rates (RGR) of the morphotypes were similar across different light conditions suggesting that factors other than light, such as water uptake efficiency, soil nutrient requirements, and perhaps seed dispersal characters may explain the habitat partitioning of morphotypes.

Species Interactions in Spruce–Fir Mixed Stands and Implications for Enrichment Planting in the Changbai Mountains, China

“…The potential mechanisms include the ecological preferences of tree species (Xu 2001), intraspecific and interspecific competition (He and Duncan 2000;Druckenbrod et al 2005), microenvironmental factors (Sugita and Tani 2001;Mori and Komiyama 2008), site condition, and chemical interactions between tree species (Silvera et al 2003;Wright et al 2005), and hence further exploration of the mechanisms responsible is needed in order to further refine enrichment planting techniques in such a context.…”

Studies on the seed biology of 100 native species of trees in a seasonal moist tropical forest, Panama, Central America

“…In addition to the comprehensive studies of BCI species by Garwood (1983) and by Daws et al (2005), which included seed mass and nursery tests, there have been a number of reports on germination patterns in natural conditions for species native to the PCW (Acuña and Garwood, 1987;Garwood, 1986a;Garwood and Lighton, 1990;Kitajima and Augspurger, 1989;Silvera et al, 2003;Sork, 1985). A considerable amount of information for species that occur in the PCW comes from studies done in Costa Rica, Mexico, or Brazil (Lorenzi, 1998;Ramalho Carvalho, 1994;Salazar, 2000;Salazar and Soihet, 2001;Vázquez-Yanes and Orozco-Segovia, 1993).…”

Enhancement of Seed Germination inTrema orientalis(L.) Blume—Potential Plant Species in Revegetation of Mine Wastelands

“…Other species of Trema-viz. T. guineensis and T. micranthalso exhibit initial dormancy for a few months due to the presence of an endogenous germination inhibitor (Vazquez-Yanes, 1998;Silvera, Skillman, & Dalling, 2003). Further research on these endogenous inhibitors may reveal the cause of initial dormancy in T. orientalis.…”