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Bug Communities and Forest Structure Modification
- 1. Bug Communities and Forest Structure Modification Andy Moldenke Carolyn Ver Linden
- 2. Bugs, bugs, bugs and more bugs! “Bugs rule!!”
- 14. Opening the canopy Open-canopy Forest
- 16. Opening the canopy Open-canopy versus closed-canopy foodwebs
- 37. Forest floor Riparian Riparian Zone Fauna Composition
- 40. Forest-floor invertebrates: Spiders Beetles Mollusks Millipedes
- 43. Forest (97 species) 1 m 5-70 m (2 species) (1 species @ 20 m) F. Köhler Distance from stream 1m 5 m 10 m 20 m 50-70 m Total r 2 = .92 Axis 1 = .12 Axis 2 = .66 DISTANCE ELEVATION
- 44. Management treatments Microclimate classes 18.0-23.9 C 45-93% RH 24.0-31.9 C 31-61% RH 32.0-44.1 C 16-36% RH Cool/humid (6 species) Warm/dry (16 species) AIR TEMP SOIL TEMP % RH
- 45. Buffer/Forest (9 species) Clearcut (19 species) Management treatments (134 species) Total r 2 = .84 Axis 1 = .18 Axis 2 = .51 Buffer Clearcut Forest
- 46. Buffer vs. Forest edge effects? 2G SP MM Edge effect Stream effect TC BP Buffer Forest
Editor's Notes
- 30 m buffer (100ft buffer in SH ranger district)
- Chose 4 forest-floor invertebrate groups Intended to represent a broad range of functional groups: herbivores (weevils and gastropods), predators (other beetles and spiders), detritivores (millipedes) 34 families in all Some are known to be useful indicator taxa (carabids),taxonomy well known (lycosids) Mollusks chosen because over 40 gastropods on the survey & manage list associated with the NW Forest Plan. Millipedes because they’re an important functional group
- Sampling design. Each site had a transect on either side of the stream, with pairs of traps at 1m, 5m, 10m, 20m, 50-70m from the stream. Traps offset, so no two traps closer than 10m to each other. This meant that at buffer site, first four rows of traps were within the buffer, 70 m traps were in the clearcut. Trapping conducted in 6 discrete 2-week sampling periods, between August 2000 and July 2002
- I’m going to be showing a series of ordinations (Alan will have explained?) The data that went into these ordinations is a matrix of species by sample units. Using combined data from all sampling periods, adults to species only.
- Again, same ordination as previous slide, but missing 5m distance. I created 3 (arbitrary) microclimate classes again, and the two ends of the horizontal axis are distinctly cool/humid or warm/dry, with some mixing inbetween. Range was much larger (18.0-44.1 C, 16-93%RH) than for forests only (18-31 C, 30-95%RH) Those samples in Swamp Peak buffer were warm/dry, and the samples circled in green are all clearcut 1m distance—span the range of microclimate classes (talk about near-stream vegetation BP vs. 2G) There were 3 shared indicator species for cool/humid and forest/buffer (3 beetles, one spider, one snail, one millipede), and 14 shared species for warm/dry and clearcut (6 beetles, 10 spiders)(no medium indicators) So, it does appear that having a riparian buffer is a more effective management treatment than harvesting to the stream edge for preserving the riparian forest community, but to how similar are the forest and buffer?… So microclimate does seem to be strongly associated with these distributions. Gradient from stream-side to forest/buffer to clearcut. How similar are the forest and the buffer?
- This ordination shows 75 sample units in all 3 treatments Samples are coded a different color for each treatment, the 70 m samples from buffer sites are coded as clearcuts. Samples at 1 m from the stream (in all treatments) are unfilled triangles. Again, you see elevation driving the ordination along the vertical axis. Now, I’ve rotated the ordination so that treatment is aligned with the horizontal axis. The green clearcut samples are all at one end of the axis, while forest and buffer sites are more mixed together on the left side of the ordination. Interestingly, the samples at 1 m distance from the stream are almost all at the extreme left side, this includes samples from all treatments. Two of the clearcut samples from next to the stream do not cluster with the rest. Also evident that at higher elevations, buffer and forest are more separate (vertically, diagonally?) Partially, due to a windthrown buffer…
- I’ve paired up the forest and buffer sites for each block, and lifted them right out of the ordination. This is just purely a visual analysis When we look at the individual block pairs of real data, no clear pattern emerges. In 2G, there appears to be no stream effect in the forest (because it’s a flat site, and seepy damp areas up to 10 m from stream?), while in the buffer, 5,10, and 20m samples are close together, but quite a bit further on the right of the axis. In MM, very similar patterns. SP also pretty similar, although the whole buffer transect is shifted to the right. TC quite similar. BP, more of stream effect in the forest. All in all, although this is all just visual, doesn’t show much effect at a community level I did an Indicator Species Analysis with buffer and forest as groups, and there was one millipede forest indicator, and 4 spider buffer indicators (two of which are very abundant in clearcuts). Might be good to look at some individual species…