Transcript Mar 18
http://www.justlogiclifescience.com.au/powerlines.html Power lines cause diseases through Static Electricity • New science reveals, not radiation, but static electricity produced by power lines interferes with the bioelectrical life process causing diseases and premature aging. • NPR had a story that farm cows tend to gather underneath the power line because their magnetic fields are confused (PNAS 2009) http://photos.innersource.com/page/45/31 Cheatgrass was brought from Eurasia to Washington State in the 1890s. In 30 years it basically took over the Western USA http://www.enn.com/enn-news-archive/1999/08/081399/cheatgrass_5005.asp http://www.rr-fallenflags.org/aft/aft.html Cheatgrass changes not only the fire frequency of a site, but also the fire volatility, intensity and the extent that an area is likely to burn in the future. The combination of fires, and low nitrogen content soil may drive out the native plants. But the cheatgrass seems to thrive under these conditions. http://www.enn.com/enn-news-archive/1999/08/081399/cheatgrass_5005.asp Merriam & Saunders (1993) Hypotheses: Very rare/difficult in landscape ecology H1: Home range sizes of all three study species would be larger in patches with a corridor than in patches w/o a corridor. H2: Habitat generalists would more likely than habitat specialists to move between them. H3: Individual movement distances would be affected by corridor presence. Cotton Mouse: Peromyscus gossypinus -- generalist Old field mouse: Perromyscus polionotus -- specialist Cotton rat: Sigmodon hispidus -- specialist http://www.nsrl.ttu.edu/tmot1/sigmhisp.htm Specialists Generalist Hypotheses: results H1: Home range sizes of all three study species would be larger in patches with a corridor than in patches w/o a corridor. not true H2: Habitat generalists would more likely than habitat specialists to move between them. true H3: Individual movement distances would be affected by corridor presence. not supported Road Corridors and Their Ecological Significances • • • How much road is there in US? Roads in US National Forests Effects of roads on plants & animals Reading: • • • Trombulak, S.C. and C.A. Russell. 2000. Conservation Biology 14(1): 18-30. Forman, R.T.T. 2000. Conservation Biology 14(1): 31-35. Semlitsch et al. 2007. Conservation Biology 21(1): 159-167. • • • • • • • Road Effects Increased mortality from road construction Increased mortality from collision with vehicles Modification of animal behavior Alteration of the physical environment Spread of exotic species Increased alteration and use of habitat by human Alteration of chemical environment 6.2 million km public roads in the US, including • 3,836,381 km secondary roads in rural area; • 1,237,198 km of primary roads in rural area; • 927,122 km of primary roads in urban area; Covers 1% of the US land All rural roads and 25% of urban roads are near natural ecosystems A minimum of 200 m effect distance caused by roads 19% of the total area of the US is directly affected by roads THE LARGEST HUMAN ARTIFACT ON EARTH! Salamander abundance near the road was reduced significantly, and salamanders along the edges were predominantly large individuals. These results indicate that the road-effect zone for these salamanders extended 35 m on either side of the relatively narrow, low-use forest roads along which we sampled. Furthermore, salamander abundance was significantly lower on old, abandoned logging roads compared with the adjacent upslope sites. These results indicate that forest roads and abandoned logging roads have negative effects on forest-dependent species such as plethodontid salamanders. Quantifying roads and road networks • • • • • • • Road density (km.km-2) Road length (km) Road width (m) Road type Road sides Road surface Other constructions (bridge, signs, etc.) Road density relative to population in various countries. Total road lengths (km) in a country are in parentheses. Forman et al. 2003. Longest among all countries! Roads in National Forests: 10% of total U.S. road length (» 380,000 miles) lies within the National Forest systems. On Jan. 22, 1998, the USDA Forest Service proposed a moratorium on the construction of new roads in some roadless areas of the National Forests. This was designed to allow time for procedures to be put in place to evaluate the need for a new management policy. Case Studies 1. 2. 3. 4. Reed et al. (1996) Brosofske (1999) Watkins (2000) Saunders et al. (2002) Data from the Rockies indicated that roads not only occupy a large proportion of the landscape, but also elevate the fragmentation and edge effects Reed et al. (1996) Study site showing: A) location of Section J, Southern Superior Uplands, within Province 212; B) Subsections within Section J. Saunders et al. (2002) Road densities (km.km-2) for LTAs (n=117) across Section J based on all primary and secondary surfaced roads. Road density (km/km2) by land cover class for LTAs of Section J. Median (line in gray box), upper and lower quartiles (box), 1.5 x inter-quartile range (whiskers) and outliers (>1.5 x interquartile range) are shown. Average % of a land cover class within an LTA falling inside road buffers of different widths Average % of the road buffer within an LTA falling in each land cover class. Housing density and soils with excellent suitability for road subgrade were positively related to road density while wetland area was negatively related. Pteridium aquilinum 15 30 0 10 Amelanchier arborea 80 0 Hieracium aurantiacum 6 0 40 Conyza canadensis 2 0 3 Trientalis borealis 1 Trifolium pratense 0 0 1000 2000 3000 JPO SPB OPB SPB CC YA2 H1 H2 Distance (m) YA1 OPB MA Percent Cover 20 0 50 100 Percent Cover of Selected Species Along the Transect PA Brosofske (1998) BOPB OPB Changes in (a) canopy cover, (b) litter cover, (c) litter depth, (d) woody-debris cover, (e) stump cover, and (f) bare ground cover with distance from unpaved forest roads in northern hardwood forests. Vertical bars represent standard deviations. 130 ( a) Canopy cover (%) ( d) Woody debris cover (%) 12 110 90 8 70 4 50 0 3 ( b) Litter cover (%) ( e) Stump cover (%) 130 2 100 1 70 40 0 15 90 ( c) Litter depth (cm) ( f) Bare ground cover (%) 11 60 7 30 0 3 0 30 60 90 120 150 0 30 Distance from Roads (m) 60 90 120 150 14 14 Changes in (a) total species richness, (b) exotic species richness, (c) Shannon-Wiener diversity (H’), (d) native species richness, (e) species richness of gramnoids, and (f) native species H’ with distance from unpaved forest roads into the forest ( a) Species richness ( d) Native species richness 12 12 10 10 8 8 3 2 ( b) Exotic species richness ( e) Gramnoids species richness 1.5 2 1 1 0.5 0 0 2.4 2.4 ( c) Total H’ ( f) Native species H’ 2 2 1.6 1.6 1.2 1.2 0 30 60 90 120 150 0 30 Distance from Roads (m) 60 90 120 150 The roads appeared to be associated with a disturbance corridor that affected site variables up to 15 m into the hardwood stands. Our results suggest that roads have associated effects that alter interior forest conditions and thus plant species composition and abundance; however, these effects are limited in depth of penetration into managed forests. Perforate the road as a barrier to animal movement by using tunnels, under passes, and other mitigation technology; Close and remove logging and other roads in remote areas to reduce disturbance effects of human access; Increase the use of soil berms, plantings, depressed roads and other construction techniques; Concentrate traffic on primary roads and minimize the conversion of secondary roads; Forman (2000) Reduce traffic noise.