Safe site for seedlings of Rhododendron metternichii var. hondoense

Abstract

Safe sites for seedlings of Rhododendron metternichii Sieb. et Zucc. var. hondoense Nakai (Ericaceae) were determined in the field in Japan. Microhabitats were classified by overlaying a distribution map of ground conditions (moss and rock patches) with crown projection diagrams. Seedlings of R. metternichii var. hondoense were highly dependent on ground conditions; seedling density was extremely low on soil but high on moss mats. Considering the canopy condition, seedling density on soil and rock was significantly lower at open sites than under tree crowns. In contrast, seedling density on moss mats was high at open sites, especially under deciduous trees. Moss–deciduous trees or moss–open sites were the best microhabitats as they usually provided both water and sunlight for seedlings. Of seedlings 0–2 cm in height, 87.7% were on moss mats while only 2.7% were on soil. This proportion of seedlings on moss and soil gradually changed with seedling development. Only 6.1% of the seedlings over 10 cm in height were on moss mats, while 81.8% were found on soil: this apparently was due to changes in ground conditions. The change from moss to soil occurred more frequently than a change from soil to moss during a 2‐year observation period. Although early seedling establishment of R. metternichii var. hondoense is highly dependent on moss mats, seedlings seem to gain tolerance for drought and instability of the substrate as they grow and they continue to survive after the disappearance of moss mats.

Population Structures in Rhododendron metternichii var. hondoense Assessed with Microsatellites and their Implication for Conservation

“…As the effect of bryophytes on seedlings differs depending on the species (Nakamura 1992), no seedlings were found on thickly developed mats of Sphagnum palustre. On the other hand, relatively thin bryophyte mats sometimes appeared to be safe sites for seedlings establishment (Cross 1981, Nakamura 1987, Kameyama et a/. 1999.…”

Patterns and levels of gene flow in Rhododendron metternichii var. hondoense revealed by microsatellite analysis

“…In seed plants, mating patterns within and among populations are decided by gene dispersal (seed and pollen movement) and establishment. Populations of long‐lived woody species normally consist of a range of individuals of various sizes (or ages) and stages of maturity with overlapping generations, such as the combinations of mature adult trees and seedlings established on special microhabitats known as ‘safe sites’ (Harmon & Franklin 1989; Shibata & Nakashizuka 1995; Kameyama et al . 1999).…”

Comparison of fine-scale spatial genetic structure of two sympatricRhododendronshrub species in forest habitat having different seed weights: A case study

“…Further, Rhododendron species are known to require limited microhabitats for germination and seedling establishment; most of their seedlings were restricted to litter-free open sites or Bryophytecovered sites (Cross, 1981;Kameyama et al, 1999;Ng and Corlett, 2000;Suzuki et al, 2000;Morimoto et al, 2003). For species with small seed reserves, such as Rhododendron species, litter acts as a physical barrier for seedling emergence and for seeds to reach the soil.…”