scholarly journals Short-Term Effects of Timber Harvest on Abundance, Territory Characteristics, and Pairing Success of Ovenbirds in Riparian Buffer Strips

The Auk ◽  
2000 ◽  
Vol 117 (3) ◽  
pp. 687-698 ◽  
Author(s):  
J. Daniel Lambert ◽  
Susan J. Hannon

AbstractIn managed forests, riparian buffer strips typically are maintained to protect water quality. If properly designed, buffer strips also may act as wildlife reserves. However, forest managers have lacked the information to develop standards for buffer strips to maximize benefits for wildlife species. We assessed the conservation potential of 20-, 100-, and 200-m wide buffers for an area-sensitive songbird in boreal mixed-wood forest in Alberta. We measured abundance, territory characteristics, and pairing success of Ovenbirds (Seiurus aurocapillus) at treatment and control lakes one year before and after upland timber harvest. After harvest, Ovenbirds were absent from 20-m buffer strips. Harvesting did not significantly influence abundance or territory size in 100-m or 200-m buffers, although territories generally became narrower. Postharvest territory position did not change in 200-m buffers, but territories in 100-m strips shifted lakeward and included more habitat adjacent to the riparian edge than before harvest. Despite this shift in territory position, males that occupied 100-m strips successfully attracted mates. High availability of regional forest cover may have muted the more pronounced effects of habitat alteration observed in other studies. Our research is among the first to evaluate individual behavioral responses to the creation of forest edges. Our data indicate that 20-m buffer strips do not support breeding Ovenbirds, whereas 100- and 200-m buffers retain Ovenbirds during the year following harvest. Long-term harvest effects may differ from those we monitored and require study, particularly as timber extraction increases in the boreal mixed-wood ecoregion.

2000 ◽  
Vol 78 (5) ◽  
pp. 740-747 ◽  
Author(s):  
Darroch M Whitaker ◽  
Allan L Carroll ◽  
William A Montevecchi

We compared the abundances of flying insects along undisturbed lakeshores and riparian buffer strips in balsam fir (Abies balsamea) forests in western Newfoundland. Insects were collected in pan traps placed on the forest floor and tanglefoot (sticky) traps suspended within the live canopy. Significantly greater numbers of insects were captured in riparian buffer strips than in undisturbed shorelines for four of five size classes in the canopy and two of five size classes in the understory. Collections were dominated by adult Diptera and Hymenoptera. Mean capture rates along buffer strips were 120-200% of the mean capture rates along undisturbed shorelines. This increase was greatest for large-bodied insects. A likely explanation for our observations is that buffer strips act as windbreaks, collecting airborne insects blown in from adjacent clearcuts and lakes. This phenomenon has been widely documented in agricultural landscapes. Understory wind speed was generally greater along buffer strips than controls, which is a reflection of increased exposure caused by clear-cutting. A concurrent parallel study conducted at the same sites investigated the effects of riparian buffering on breeding bird assemblages. Ubiquitous insectivorous birds, including the yellow-rumped warbler (Dendroica coronata) and blackpoll warbler (Dendroica striata), were more abundant along buffer strips than undisturbed shorelines, possibly in response to increased prey availability. Increased food availability may in part explain the high numbers of insectivorous birds typically observed in riparian buffer strips in boreal forests.


New Forests ◽  
2011 ◽  
Vol 42 (2) ◽  
pp. 241-265 ◽  
Author(s):  
Julien Fortier ◽  
Daniel Gagnon ◽  
Benoit Truax ◽  
France Lambert

2003 ◽  
Vol 33 (5) ◽  
pp. 755-762 ◽  
Author(s):  
Ian G Warkentin ◽  
Allison L Fisher ◽  
Stephen P Flemming ◽  
Shawn E Roberts

We examined the distribution and foraging behaviour of northern waterthrushes (Seiurus noveboracensis) in recently harvested and intact landscapes of Newfoundland. Data were collected along six 1-km segments of stream and adjoining upland habitat resulting in four treatments (harvested or intact, upland or stream) with three replicates each. Although known as a riparian specialist, we found waterthrush territories equally distributed across intact upland and riparian habitats. However, few waterthrushes occupied harvested uplands, while large numbers packed into riparian buffer strips adjacent to these 5- to 10-year-old postharvest clearcuts. Arthropod abundance and biomass were highly variable between years and across the four treatments, generating significant year × treatment interaction effects. Riparian habitat (in both intact and harvested areas) had consistently greater numbers of arthropod prey and more biomass than either upland habitat type. Northern waterthrushes foraging in riparian habitat adjacent to harvested uplands had lower attack rates and more frequent long flights than waterthrushes foraging in the intact treatment types. Prolonged packing of individuals into riparian buffer strips, and apparent adverse affects on waterthrush foraging efficiency, raise concerns about the effectiveness of buffer strips for sustaining viable populations of terrestrial riparian habitat specialists.


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