[obol] foraging birds increase tree growth

[Romain Cooper]

This is just one study on one forest type in one 
location, But I'm still impressed.

Romain

>"More than anything, this study underscores the 
>importance of preserving the ecological 
>communities in the forest, and not just the trees," Mooney said.
>
>
><http://www.sciencedaily.com/releases/2007/08/070801091253.htm>http://www.sciencedaily.com/releases/2007/08/070801091253.htm
>
>Source: <http://www.colorado.edu>University of Colorado at Boulder
>Date: August 6, 2007
>
>
>
>Chickadee, Nutchatch Presence In Conifers Increases Tree Growth, Says Study
>
>
>
>
>
><http://www.sciencedaily.com>Science Daily ­ 
>Chickadees, nuthatches and warblers foraging 
>their way through forests have been shown to 
>spur the growth of pine trees in the West by as 
>much as one-third, according to a new University of Colorado at Boulder study.
>[]
>
>Chickadees and nuthatches have been shown to 
>increase the growth of conifers in the West. (Credit: Copyright Bill Schmoker)
>
>----------
>The study showed birds removed various species 
>of beetles, caterpillars, ants and aphids from 
>tree branches, increasing the vigor of the 
>trees, said study author Kailen Mooney. Mooney, 
>who conducted the study as part of his doctoral 
>research in CU-Boulder's ecology and 
>evolutionary biology department, said it is the 
>first study to demonstrate that birds can affect the growth of conifers.
>
>"In a nutshell, the study shows that the 
>presence of these birds in pine forests 
>increased the growth of the trees by helping to 
>rid them of damaging insects," said Mooney. 
>"From the standpoint of the trees, it appears 
>that the old adage, 'the enemy of my enemy is my friend,' holds true."
>
>A paper on the subject by Mooney was published 
>in the August issue of Ecology. In the study, 
>Mooney used mesh netting to exclude birds from 
>ponderosa pine limbs in the U.S. Forest 
>Service-managed Manitou Springs Experimental 
>Forest northwest of Colorado Springs for three 
>years. The results showed that branches on 42 
>trees rigged to exclude birds had 18 percent 
>less foliage and 34 percent less wood growth by the end of the study.
>
>Mooney collected about 150,000 insect specimens 
>from the mountain study area, identifying more 
>than 300 separate spider and insect species 
>collectively known as arthropods. The trees used 
>in the study were set up to exclude birds, ants, 
>or both, since ants also can have significant 
>impacts on other arthropods, he said.
>
>"The study indicates that pine canopies are very 
>complex systems with an unexpected level of 
>biodiversity," said Mooney. "Forest managers 
>really need to look at the big picture of 
>ecosystems and not just focus on trees when 
>implementing regulations aimed at encouraging the growth of healthy forests."
>
>The study also has implications for large areas 
>of the West ravaged by forest fires in recent 
>years, he said. A number of once formidable 
>stands of mature ponderosa have been burned and 
>logged and subsequently replaced by smaller 
>pines that offer limited breeding opportunities 
>for cavity-nesting birds like chickadees and 
>nuthatches, which nest and lay their eggs in the 
>holes of large trees and dead snags.
>
>"This is a very rigorous study that essentially 
>shows that even modest little birds like 
>chickadees and nuthatches can help improve the 
>heath of the trees, which are the monarchs of 
>the forest," said CU-Boulder biology Professor 
>Yan Linhart. Linhart was Mooney's doctoral 
>adviser at CU-Boulder and also co-authored a 
>study with Mooney in 2006 in the journal Animal 
>Ecology. The study compared the effects of birds 
>on pine with their effects on dwarf mistletoe, a 
>parasitic plant on ponderosas throughout the West.
>
>Mooney said the activity of the birds also was 
>shown to change the chemical "flavor" of the 
>trees, which may have implications for 
>infestations by damaging insects like bark 
>beetles that have ravaged pine forests in the 
>West. Chemicals in trees known as terpenes, 
>which give vegetation distinctive odors, have 
>been implicated in the resistance of trees to 
>parasites and plant-eating insects, he said.
>
>By removing insects, the birds indirectly 
>altered the terpene composition of pine tissues, 
>said Linhart. The alteration of terpene "flavor" 
>can have wide ranging effects, since terpenes 
>influence decisions that creatures like bark 
>beetles, porcupines and squirrels make when 
>deciding which trees to eat, said Linhart.
>
>"Terpenes act a bit like an immune system by 
>essentially fending off attacks by birds and 
>mammals," said Linhart. "One of the fascinating 
>results of this study is that birds affect how this immune system functions."
>
>The study also showed that chickadees and 
>nuthatches disrupt a mutually beneficial 
>relationship ants have with aphids, which feed 
>on plant tissue known as phloem sap that carries 
>nutrients through the tree, Mooney said. While 
>some ant species "tend" aphid colonies -- 
>protecting them from predators in exchange for 
>their carbohydrate-high "honeydew" secretions - 
>feeding activity by birds can disrupt this 
>relationship, triggering aphid population 
>decreases and increases in tree growth.
>
>"These ponderosa forests have very complex food 
>chains," Linhart said. "In essence the 
>nuthatches and chickadees act as tree 
>protectors, keeping check the insects that can 
>have deleterious effects on forest vigor."
>
>The birds in the study included the mountain 
>chickadee, the red-breasted nuthatch, the pygmy 
>nuthatch and the yellow-rumped warbler. All but 
>the warbler are year-round residents of ponderosa pine forests in Colorado.
>
>"More than anything, this study underscores the 
>importance of preserving the ecological 
>communities in the forest, and not just the trees," Mooney said.
>
>The study was funded by the USFS Rocky Mountain 
>Research Station headquartered in Fort Collins 
>and by CU-Boulder. Mooney was a postdoctoral 
>researcher at Cornell University in 
>2006-07.  Mooney, who received his doctorate 
>from CU-Boulder in 2004, will become a biology 
>department faculty member at the University of 
>California, Irvine, in fall 2007.
>
>Note: This story has been adapted from a news 
>release issued by University of Colorado at Boulder.
>
>----------------------------

Siskiyou Biological Services LLC
Romain Cooper
10398 Takilma Road
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home office 541-592-2311
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