Changes in size of soil seed bank in Robinia pseudoacacia L. (Leguminosae), an exotic tall tree species in Japan: Impacts of stand growth and apicultural utilization

Published Date
Received 20 January 2010, Revised 22 May 2010, Accepted 26 May 2010, Available online 19 June 2010.

https://doi.org/10.1016/j.foreco.2010.05.036

Author
KazuhikoMasakaa. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceOpens the author workspaceOpens the author workspace. Author links open the author workspace.KenjiYamadaa. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace1. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.YasuhiroKoyamab. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace2. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.HajimeSatoa. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace1. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.HirokazuKona. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace1. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.HiroyukiToritaa. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace1. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace

a

Hokkaido Research Organization, Forestry Research Institute, Bibai, Hokkaido 079 0198, Japan

b

Nagano Prefecture Forest Research Center, Shiojiri, Nagano 399 0711, Japan

Abstract

This study examined the factors that influence the size of a soil seed bank in Robinia pseudoacacia stands. We proposed two hypotheses: the amount of buried seeds of R. pseudoacacia is proportional to stand biomass rather than stand age, and apicultural utilization influences the size of the soil seed bank. R. pseudoacacia generally produces seeds with various degrees of physical dormancy. In addition, this tree is short-lived, and fecundity declines after 30–40 years in relation to tree vigor. However, R. pseudoacacia is intensively used in apiculture as an important honey source, and supply of honeybees by beekeepers could influence seed crops. We investigated 25 plantations in Hokkaido (Central, Hidaka, and Oshima) and in Nagano, Japan, where many naturally regenerated R. pseudoacacia stands occur. We found great variation in the size of the soil seed bank among stands, ranging from 13,757 to 6.4 seeds m−2 per plot. A generalized linear mixed model revealed that both basal area (BARp) and apicultural utilization best explained the size of the soil seed bank. Both the positive effect of BARp and small contribution of stand age to the model implied that the soil seed bank is transitory, and will not persist for very long time. The large contribution of apicultural utilization to the size of the soil seed bank implied pollinator limitation under natural conditions. R. pseudoacacia often has large flower crops, and native pollinators can not keep up with the demand for pollination. Thus, the supply of honeybees by beekeepers should improve the pollination success of R. pseudoacacia. From these results, we conclude that we must consider stand history with respect to apicultural utilization if the land is harvested or a stand declines.

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