TY - JOUR

T1 - Individual-tree radial growth in a subtropical broad-leaved forest

T2 - The role of local neighbourhood competition

AU - von Oheimb, Goddert

AU - Lang, Anne C.

AU - Bruelheide, Helge

AU - Forrester, David I.

AU - Waesche, Ilka

AU - Yu, Mingjian

AU - Haerdtle, Werner

PY - 2011/2/1

Y1 - 2011/2/1

N2 - Establishing the competitive relationships at the local neighbourhood level is essential for improving our understanding of tree growth dynamics in structurally heterogeneous and species-rich forests. We studied the competitive interactions influencing individual-tree five-year radial growth of the two species Castanopsis fargesii (Franch.) and Quercus fabri (Hance) in a diverse young secondary evergreen broad-leaved forest (EBLF) in eastern China. Different spatially explicit individual-based competition indices were examined for their effectiveness at predicting radial growth. These indices were based on one of the three tree size variables diameter at breast height (dbh), total height, and crown projection area and were combined with different approaches to identify potential competitors. Furthermore, we tested for competitive equivalence of conspecific and heterospecific neighbours and analysed the effects of local diversity, initial dbh (measured at the beginning of the five-year growth period) and abiotic environmental variables on individual-tree radial growth. Competition accounted for up to 78% and 75% of radial growth variation in C. fargesii and Q. fabri, respectively. The best results were provided by competition indices using crown projection area as the variable describing tree size and the angular height method as the approach to identify potential competitors (i.e. neighbours greater than the minimum angular height, measured from the base of the target trees, are selected as competitors). Competitive equivalence of conspecific and heterospecific neighbours was found in C. fargesii, whereas heterospecifics were stronger competitors than conspecifics in Q. fabri. We could not detect diversity effects on radial growth. The addition of initial dbh or abiotic environmental variables as further explanatory variables failed to improve the predictive ability of growth models. Our results indicate that diameter growth in this EBLF is largely a function of local neighbourhood competition and suggest that the mode of competition is primarily size-asymmetric. It appears that there may be high competitive equivalence among different species, but this remains to be experimentally tested.

AB - Establishing the competitive relationships at the local neighbourhood level is essential for improving our understanding of tree growth dynamics in structurally heterogeneous and species-rich forests. We studied the competitive interactions influencing individual-tree five-year radial growth of the two species Castanopsis fargesii (Franch.) and Quercus fabri (Hance) in a diverse young secondary evergreen broad-leaved forest (EBLF) in eastern China. Different spatially explicit individual-based competition indices were examined for their effectiveness at predicting radial growth. These indices were based on one of the three tree size variables diameter at breast height (dbh), total height, and crown projection area and were combined with different approaches to identify potential competitors. Furthermore, we tested for competitive equivalence of conspecific and heterospecific neighbours and analysed the effects of local diversity, initial dbh (measured at the beginning of the five-year growth period) and abiotic environmental variables on individual-tree radial growth. Competition accounted for up to 78% and 75% of radial growth variation in C. fargesii and Q. fabri, respectively. The best results were provided by competition indices using crown projection area as the variable describing tree size and the angular height method as the approach to identify potential competitors (i.e. neighbours greater than the minimum angular height, measured from the base of the target trees, are selected as competitors). Competitive equivalence of conspecific and heterospecific neighbours was found in C. fargesii, whereas heterospecifics were stronger competitors than conspecifics in Q. fabri. We could not detect diversity effects on radial growth. The addition of initial dbh or abiotic environmental variables as further explanatory variables failed to improve the predictive ability of growth models. Our results indicate that diameter growth in this EBLF is largely a function of local neighbourhood competition and suggest that the mode of competition is primarily size-asymmetric. It appears that there may be high competitive equivalence among different species, but this remains to be experimentally tested.

KW - Biology

KW - BEF-China

KW - Competitive equivalence

KW - Competition index

KW - Crown area

KW - Jiangxi Province

KW - Mixed forest

KW - Size-asymmetric competition

KW - BEF-China

KW - Competition index

KW - Competitive equivalence

KW - Crown area

KW - Jiangxi Province

KW - Mixed forest

KW - Size-asymmetric competition

KW - Ecosystems Research

UR - http://www.scopus.com/inward/record.url?scp=78651243516&partnerID=8YFLogxK

U2 - 10.1016/j.foreco.2010.10.035

DO - 10.1016/j.foreco.2010.10.035

M3 - Journal articles

VL - 261

SP - 499

EP - 507

JO - Forest Ecology and Management

JF - Forest Ecology and Management

SN - 0378-1127

IS - 3

ER -