The influence of spatial patterns of damping-off disease and arbuscular mycorrhizal colonization on tree seedling establishment in Ghanaian tropical forest soil
The influence of spatial patterns of damping-off disease and arbuscular mycorrhizal colonization on tree seedling establishment in Ghanaian tropical forest soil
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DOI：
10.1111/j.0022-0477.2004.00917.x
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发表时间：
2004-10-01
影响因子：
5.5
通讯作者：
Mason, PA
中科院分区：
文献类型：
--
作者：
Hood, LA;Swaine, MD;Mason, PA
1 Milicia regia（桑科）是一种雌雄异株的光需求（先锋）西非木材树。利用日光温室试验研究了光照和土壤源对植物生长的影响在加纳的实验包括光照处理，（2%和20%的无遮蔽辐照度），三种土壤源结果表明，光照、光照强度、光照强度、光照时间、光照时间土壤源和杀菌剂对幼苗死亡率和生物量的影响。生物量更大，死亡率降低在较高的辐照度。杀菌剂的应用降低死亡率在2%的辐照度，但在20%没有显着的影响，虽然AM感染的幼苗生长在土壤中的成人以下严重减少。死亡率是最大的雌树下的土壤中，至少在远离成年同种的土壤。然而，在20%辐照度下，雌性下方土壤中的生物量更大，可能是因为增强了AM定植：幼苗根系被AM真菌侵染的百分比显著高于成年种，生物量积累与AM真菌侵染的根长显著相关。土壤来源和杀菌剂处理证明了空间效应对热带森林幼苗建立的复杂性。虽然有明确的证据表明病原体介导的效应为Janzen-Connell间隔机制提供了支持，但逃离母树增加了到达间隙的机会，AM真菌群落的空间差异可能起相反的作用，并增强幼苗生长接近成年同种。5非生物和生物因素之间相互作用的复杂性以及这些因素在空间上变化的方式，影响幼苗补充可能是维持热带森林树种多样性的一个重要因素。
1 Milicia regia (Moraceae) is a dioecious light-demanding (Pioneer) timber tree of West Africa. Experiments in shadehouses were used to examine the influence of light and soil source (beneath and away from conspecific adults) on mortality and growth of its seedlings in relation to fungal pathogens and arbuscular mycorrhizal (AM) colonization.2 The experiment in Ghana included treatments for light (2% and 20% of unshaded irradiance), three soil sources (under female, under male and 200 m distant from adults), and two different fungicide treatments.3 The results showed significant effects of irradiance, soil source and fungicide on both seedling mortality and accumulated biomass. Biomass was greater and mortality reduced at higher irradiance. Fungicide application reduced mortality in 2% irradiance, but had no significant effects at 20%, although AM infection of seedlings grown in soils from beneath adults was severely reduced. Mortality was greatest in soil from beneath female trees and least in soil distant from adult conspecifics. However, biomass in 20% irradiance was greater in soil from beneath females, possibly because of enhanced AM colonization: seedlings had a significantly higher percentage root length colonized by AM fungi beneath adult conspecifics, and biomass accumulation was significantly correlated with root length colonized by AM fungi.4 There were significant interactions amongst light, soil source and fungicide treatments that attest to the complexity of spatial effects on seedling establishment in tropical forest. Whilst there was clear evidence of pathogen-mediated effects that provides support for Janzen-Connell spacing mechanisms, and escape from the parent tree increases the chances of arriving in gaps, spatial differences in AM fungal communities may act in the opposite direction and enhance seedling growth close to adult conspecifics.5 The complexity of interactions between abiotic and biotic factors and the way in which these factors can vary spatially to affect seedling recruitment may be an important factor contributing to the maintenance of tree species diversity in tropical forests.