226 



Tfirc.slridl Ecosxslems — Our Living Kf.vcKM f.v 



Forests logged and burned . 



Fig. 3a. Rates of change rrom a 

 tall-grass prairie and oak savanna 

 in the Indiana Dunes. IN. based on 

 pollen from tree species. 



Fig. 3b. Rates of change from a 

 boreal pme torest at Pictured 

 Rocks. MI. based on pollen from 

 tree species. 



Fig. 3c. Rates of change from 

 coastal sage scrub on Santa Rosa 

 Island. CA, based on pollen from 

 an estuary. 



Indiana Dunes, IN 



Indiana Dunes National Lakeshore 



Howes Prairie Marsh 



■S 1 



I I I I I I I I I I I I I 1 1 I I I 1 11 I I { I I I {[ I 11 I I II I I I I I 

 2000 B,C 100DBC AD 1000 



Year 



Forests logged and burned 



12-MileBog, Ml 



Pictured Rocl<s National Lakeshore 



— 1 



\ Lake Superior declines 

 creating bog 



500BC AD 500 AD 1000 AD 1500 



Year 



California Coastal Sage Scrub 



Fossil pollen was analyzed fiom an estuary 

 on Santa Rosa Island oft" the coast of southern 

 California (Cole and Liu 1994). The semi-arid 

 landscape around the estuary is covered with 

 coastal sage scrub, chapairal. and grassland. 

 This site, within Channel Islands National Park, 

 is one of the least affected areas in this region of 

 rapidly expanding urbanization, although the 

 island's native plants and animals were not well 

 adapted to withstand the grazing of the large 

 animals introduced with the ranching era of the 

 1800's. This island, which had no native large 

 herbi\'ores. became populated with thousands of 

 sheep, cattle, horses, goats, pigs. deer, and elk. 

 The National Park Service is removing many of 

 the large herbi\ ores, although most of the island 

 remains an active cattle ranch. 



All pollen types from 33 samples spread 

 over the last 4,600 years were analyzed. The 

 rates of change in the pollen were similar to 

 those observed from the other sites (Fi2. 3c). 



Large grazing 

 animals introduced 



Santa Rosa Island, CA 

 Channel Islands National Park 

 Abalone Rocks Marsh 



2000 B.C. 1000 B.C. 



A.D. 1000 



Southern Utah Desert 



Because fossil pollen is usually preserved in 

 accumulating sediments of wetlands, different 

 paleoecological techniques are necessary in arid 

 areas. In western North America, fossil deposits 

 left by packrats (Neotoimi spp.) have proven a 

 useful source of paleoecological data 

 (Betancourt et al. 1990). Past desert vegetation 

 can be reconstmcted by analyzing bits of leaves, 

 twigs, and seeds collected by these small 

 rodents and incorporated into debris piles in 

 rock shelters or caves. These debris piles can be 

 collected, analyzed, and radiocarbon dated. 



The vegetation history of a remote portion of 

 Capitol Reef National Park (Hartnett Draw) was 

 reconstructed through the analysis of eight 

 packrat middens ranging in age from to 5.450 

 years (Cole 1995). The vegetation remained 

 fairly stable throughout this period until the last 

 few hundred years. The most recent deposits 

 contain many plants associated with overgrazed 

 areas such as whitebark rabbitbrush 

 (Ch)-ysothamiuis visidiflorus), snakeweed 

 {Giitterezia sawthrae), and greasewood 

 {Sairohatus vcnniciilatiis), which were not 

 recorded at the site before settlement. 



Conversely, other plants that are extremely 

 palatable to grazing animals were present 

 throughout the last 5.450 years, only to disap- 

 pear since settlement. Plant species preferred by 

 sheep and cattle, such as winterfat (Cenitoides 

 hmala) and rice grass (Stipa hymenoides). dis- 

 appeared entirely, while many other palatable 

 plant species declined in abundance after 5,000 

 years of comparative stability. 



The past rates of vegetation change for this 

 site were calculated in a manner similar to the 

 fossil pollen records (Fig. 3d). Although the rate 

 of change calculation is less precise than the 

 fossil pollen records because there were fewer 

 samples, the results show a similar pattern. The 

 rate of vegetation change is highest between the 

 two most recent records. 



Although this area is still grazed by cattle 

 today through grazing leases to private ranchers 

 from the National Park Service, much of the 



0.4 



Large grazing 

 animals introduced 



Capitol Reef National Park. UT 

 Hartnet Draw 



~ 0.2 



'I'M'' 

 1000 BC 



AD 1000 



Year 



Year 



Fig. 3d. Rates of change from desert vegetation at Capitol 

 Reef, UT, based on plant fossils in packrat middens. 



