Effects of pruning on Colophospermum mopane leaf phenology and production

2019 ◽  
Vol 58 (1) ◽  
pp. 145-148
Author(s):  
Rudzani A. Makhado ◽  
Martin J. Potgieter ◽  
Wilmien J. Luus‐Powell

2021 ◽  
Vol 489 ◽  
pp. 119085
Author(s):  
Zhenzhao Xu ◽  
Qijing Liu ◽  
Wenxian Du ◽  
Guang Zhou ◽  
Lihou Qin ◽  
...  


Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 425
Author(s):  
Noviana Budianti ◽  
Hiromi Mizunaga ◽  
Atsuhiro Iio

Unmanned aerial vehicles (UAV) provide a new platform for monitoring crown-level leaf phenology due to the ability to cover a vast area while offering branch-level image resolution. However, below-crown vegetation, e.g., understory vegetation, subcanopy trees, and the branches of neighboring trees, along with the multi-layered structure of the target crown may significantly reduce the accuracy of UAV-based estimates of crown leaf phenology. To test this hypothesis, we compared UAV-derived crown leaf phenology results against those based on ground observations at the individual tree scale for 19 deciduous broad-leaved species (55 individuals in total) characterized by different crown structures. The mean crown-level green chromatic coordinate derived from UAV images poorly explained inter- and intra-species variations in spring leaf phenology, most probably due to the consistently early leaf emergence in the below-crown vegetation. The start dates for leaf expansion and end dates for leaf falling could be estimated with an accuracy of <1-week when the influence of below-crown vegetation was removed from the UAV images through visual interpretation. However, a large discrepancy between the phenological metrics derived from UAV images and ground observations was still found for the end date of leaf expansion (EOE) and start date of leaf falling (SOF). Bayesian modeling revealed that the discrepancy for EOE increased as crown length and volume increased. The crown structure was not found to contribute to the discrepancy in SOF value. Our study provides evidence that crown structure is a pivotal factor to consider when using UAV photography to reliably estimate crown leaf phenology at the individual tree-scale.





2015 ◽  
Vol 30 (2) ◽  
pp. 206-214 ◽  
Author(s):  
Jingjing Yin ◽  
Jason D. Fridley ◽  
Maria S. Smith ◽  
Taryn L. Bauerle




2006 ◽  
Vol 100 (2) ◽  
pp. 265-279 ◽  
Author(s):  
J FISHER ◽  
J MUSTARD ◽  
M VADEBONCOEUR
Keyword(s):  


1994 ◽  
Vol 72 (10) ◽  
pp. 1560-1560
Author(s):  
Shigeru Uemura




2009 ◽  
Vol 15 (4) ◽  
pp. 961-975 ◽  
Author(s):  
XAVIER MORIN ◽  
MARTIN J. LECHOWICZ ◽  
CAROL AUGSPURGER ◽  
JOHN O'KEEFE ◽  
DAVID VINER ◽  
...  


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