TITLE:
The Influence of Avian Biodiversity and a Weedy Understorey on Canopy Arthropod Assembly
AUTHORS:
Kathryn Teare Ada Lambert, Nigel R. Andrew, Paul G. McDonald
KEYWORDS:
Despotic Birds, Disturbance, Insects, Canopy, Tritrophic Relationships
JOURNAL NAME:
Open Journal of Ecology,
Vol.4 No.16,
December
15,
2014
ABSTRACT:
Identifying the
factor causing species decline from a multitude of potential disturbances is
essential for successful management. Invasive species are often drivers of
decline, either through direct effects such as recruitment limitation, or
through indirect effects such as habitat modification that facilitate biota
changes in other taxa. In this study, we tested the importance of bird
predation on arthropods in eucalypt canopies in wet sclerophyll forest that had
been invaded by the understorey weed Lantana
camara. A strong top-down effect is in agreement with studies that show elevated
numbers of insectivorous birds, such as the despotic bell miner, Manorina melanophrys, reduce damaging
herbivorous insect numbers and their effect on tree health. Abundance, order and
family composition were compared among sites, feeding guilds, among the
presence and absence of a despotic bird, and among presence and absence within
sites, using a three-way nested Multivariate Analysis of Variance (MANOVA), and
tested our representation of insect feeding guilds with rarefaction curves. In
total, we found arthropods from 20 families on eucalypt trees, 16 where bell
miners were present and 18 where they were absent (a sampling efficiency of 78%
and 92% of families based on the Chao-I index). Overall, there was a difference
in the abundance of insects in areas where bell miners were present (n = 181), and where they were absent (n = 67). There was also a difference in
the families present in areas with bell miners and without them. Under some
conditions, despotic birds may not change the insect canopy community. Further
studies should examine the effects of a despotic bird on the insect canopy
community in a variety of conditions and throughout their range.