TY - JOUR
T1 - Neighborhood aggregation effect and its effective scale on reproductive success in Shorea laxa (Dipterocarpaceae)
AU - Takeuchi, Yayoi
AU - Samejima, Hiromitsu
AU - Nakagawa, Michiko
AU - Diway, Bibian
AU - Nakashizuka, Tohru
N1 - Funding Information:
Acknowledgments The authors thank to Ms. L. Chong (Forest Research Centre, Sarawak) for her permission and assistance for us to conduct this work in Sarawak. We are also grateful to Dr. K. Kitajima and an anonymous reviewer for valuable suggestions for our early manuscript. Dr. S. Sakai, Dr. T. Kenta and members of laboratory of forest biology in Kyoto University also gave us valuable suggestions for this study. We also thank Dr. M. Aiba and Mr. B. Jingan for field work assistant. This study was financially supported by the Grant for the Biodiversity Research of the 21st Century COE, MEXT Japan (A14), research grant from Showa Shell Sekiyu and the JSPS Research Fellowship for Young Scientists for Y. Takeuchi.
PY - 2010/3
Y1 - 2010/3
N2 - This study investigated whether reproductive success is affected by the intensity of neighborhood aggregation of adults in the tropical tree Shorea laxa. We focused on three processes in the early reproductive stages: seed maturation; seed survival (categorizing sound seed, predation by insects and predation by vertebrates) in pre-seed dispersal; and seedling survival in the post-seed dispersal stage. We used a model selection procedure to examine the aggregation effect on reproductive success. The intensity of neighborhood aggregation was represented by the neighborhood aggregation index, which contains the adult number within a specific radius and the distances to neighboring adults (weight of proximity). Then, we evaluated the models exhaustively with the aggregation index having different scales (radius and weight of proximity) to assess the scale on which aggregation had significant effects. In particular, the best effective neighborhood scale, which is defined as the scale of the index in the model with minimum Akaike information criterion, was examined to compare those scales among processes. We found that the probability of seed maturation, seed survival and seedling survival decreased with the aggregation index at specific scales. This suggests that aggregation influenced reproductive success negatively in both the pre- and post-seed dispersal stages. However, the selected radii differed among processes: >200 and 130 m in pre- and post-seed dispersal stages, respectively. The selected weight of proximity also seemed to have a weak effect on all processes and was not different among processes.
AB - This study investigated whether reproductive success is affected by the intensity of neighborhood aggregation of adults in the tropical tree Shorea laxa. We focused on three processes in the early reproductive stages: seed maturation; seed survival (categorizing sound seed, predation by insects and predation by vertebrates) in pre-seed dispersal; and seedling survival in the post-seed dispersal stage. We used a model selection procedure to examine the aggregation effect on reproductive success. The intensity of neighborhood aggregation was represented by the neighborhood aggregation index, which contains the adult number within a specific radius and the distances to neighboring adults (weight of proximity). Then, we evaluated the models exhaustively with the aggregation index having different scales (radius and weight of proximity) to assess the scale on which aggregation had significant effects. In particular, the best effective neighborhood scale, which is defined as the scale of the index in the model with minimum Akaike information criterion, was examined to compare those scales among processes. We found that the probability of seed maturation, seed survival and seedling survival decreased with the aggregation index at specific scales. This suggests that aggregation influenced reproductive success negatively in both the pre- and post-seed dispersal stages. However, the selected radii differed among processes: >200 and 130 m in pre- and post-seed dispersal stages, respectively. The selected weight of proximity also seemed to have a weak effect on all processes and was not different among processes.
KW - Neighborhood aggregation effect
KW - Post-dispersal seed predation
KW - Pre-dispersal seed predation
KW - Proximity
KW - Seedling survival
UR - http://www.scopus.com/inward/record.url?scp=77951499512&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77951499512&partnerID=8YFLogxK
U2 - 10.1007/s10265-009-0265-1
DO - 10.1007/s10265-009-0265-1
M3 - Article
C2 - 19894085
AN - SCOPUS:77951499512
VL - 123
SP - 249
EP - 259
JO - Journal of Plant Research
JF - Journal of Plant Research
SN - 0918-9440
IS - 2
ER -