The Growth of Four Tree Species Seedlings on Soil and Decayed Wood of Pinus densiflora
The Growth of Four Tree Species Seedlings on Soil and Decayed Wood of Pinus densiflora
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发表时间：
2017
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通讯作者：
Fukasawa Yu;Y. Fukasawa
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作者：
Fukasawa Yu;Y. Fukasawa
Decayed wood provides regeneration microsites for a variety of tree seedlings, whereas the mechanisms of species-specific preferences for decayed wood, their decay types, and soil are poorly known. To evaluate the effects of chemical and biological characteristics of the substrates on seedling preference, I investigated the biotic and abiotic effects of different substrates on the aboveand belowground growth of seedlings of 4 tree species commonly occurring in post-Pine Wilt Disease (PWD) forests. Seedlings were grown in microcosms including autoclaved or non-autoclaved substrates (3 types: white-rotted wood, brown-rotted wood, and soil) for 4 months. After retrieval, the aboveand belowground growth of the seedlings was measured. Pinus densi ora seedlings experienced greater growth in nons-autoclaved rather than autoclaved substrates; however, growth was affected to a lesser extent by the differences in substrates. In contrast, Cryptomeria japonica seedlings experienced greater growth in soil than in woods; however, growth was not affected by autoclaving. Aboveground growth of Clethra barbinervis seedlings was greater in soil and autoclaved brownrotted wood than in other wood substrates. The growth of Eurya japonica seedlings was greater in soil than in woods. Seedlings of the 3 species, excluding C. barbinervis, showed plasticity in the shoot/root ratio against substrate difference. The relative importance of biotic and abiotic factors for the aboveand belowground growth of seedlings differ among tree species, which may partly explain species-dependent preferences for different microsites on the forest oor when regenerating in post-PWD forests. Introduction Microsite heterogeneity plays an important role in plant population dynamics and species diversity maintenance in forest ecosystems (Harmon and Franklin 1989; Nakashizuka 2001). Different tree species favor speci c microsites for seedling regeneration, reflecting their life-history traits associated with physiological and morphological responses to abiotic and biotic environmental conditions (Leck and Outred 2008). Allocation to aboveand belowground growth is one of the most conspicuous traits characterizing the initial responses of seedlings to their environments (Kohyama and Grubb 1994; Doi et al. 2008). Thus, it is important to determine allocations of seedlings to aboveand belowground growth for understanding their preferences pertaining to forest microsites. Among the microsites on forest floors, coarse woody debris (CWD) provides important refuges for seedling establishment in various forest ecosystems (Fukasawa 2012). Although CWD generally contains relatively lower concentrations of nutrients compared with soil (Goodman and Trofymow 1998; Baier et al. 2006), it can contain greater concentrations of nutrients compared with soil in some cases (Takahashi et al. 2000; Fukasawa 2015a). Furthermore, the nature of microbial communities inhabiting CWD, particularly the low level of soil-borne pathogens, often contributes to good growth performances of pathogen-susceptible
