A novel approach to selecting a competition index: the effect of competition on individual-tree diameter growth of Calabrian pine
Küçük Resim Yok
Tarih
2018
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Canadian Science Publishing, Nrc Research Press
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
In this study, we evaluated the performance of 18 competition indices composed of nine distance-dependent and nine distance-independent indices in explaining the variation in individual-tree diameter growth of Calabrian pine (Pinus brutia Ten.) in the central Mediterranean region of Turkey. The data were obtained from 432 sample plots with varying stand age, site index, and stand density. To evaluate the performance of each competition index, the mean square error reduction approach was used relative to the noncompetition. Also, this study compared fixed and mixed effects models to analyze diameter growth. Statistical analyses showed that the best distance-independent competition indices performed as well as the best distance-dependent competition indices. The distance-independent competition index of Schroder and Gadow (1999; Can. J. For. Res. 29(2): 280-283, doi:10.1139/x98-199) performed best and is recommended for use in future growth and yield models to be used in the central Mediterranean region of Turkey. Also, the best selection of competitive neighbors was achieved using the area of influence overlap method, whereas the fixed-radius and angle count sampling methods had no significant improvement in quantifying the competition effects. On the other hand, all mixed effects models provided much better fits than their fixed model counterparts.
Açıklama
Anahtar Kelimeler
diameter growth, competition indices, selection of competitor, fixed and mixed models, Calabrian pine
Kaynak
Canadian Journal Of Forest Research
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
48
Sayı
10
