» 



57 



The influence of habitat alteratioi euround the poids could 

 have an effect on their suooessic»vil trends. In cases where 

 logging has occurred near the habitat margins, an increase 

 in siltatioi rate into the pcnds vrould be esqiected. Such a 

 change would probably influence both the nature of the 

 bottan substrates and the vegetational corposition of the 

 sites. As discussed above, H. aquatilis occurs most 

 frequently and most densely in ponds with firm, ccxisolidated 

 organic clay bottan sediments. It also is frequently found 

 in more open areas within the ponds. Thus, increases in 

 bottan sedimentation, and subsequent oaipetition fran other 

 vegetation, could both have an adverse effect on the 

 viability of H. aquatilis populations. 



Inpacts from grazing could also potentially influence the 

 vegetation caifxasition of the ponds, through increased 

 nutrient levels emd subsequent suooessional changes. Also, 

 tranpling of the bottan sediments may adversely affect the 

 seed bank, and the consolidated substrate which appeeurs to 

 be neoesseury for vigorous germination. There is sone 

 indication that the historical site in California may have 

 been negatively affected by livestock tranpling (Griggs and 

 Dibble 1979) . However, in Spokane County, Washington, 

 several of the ponds containing H. aquatilis have been 

 significeuTtly edtered by past and current grazing. Sane of 

 these sites have possibly been grazed for 50 years or more, 

 emd the species has persisted, suggesting that in sane 

 situations it may be fairly tolerant to such land use, at 

 least in the short term (J. Gamon, pers. ocmn.). 



3. current management policies and actions: In Montana, a 



three-yeeu: inventory and analysis program proposal has been 

 subndtted to the Flathead National Forest by the Montana 

 Natural Heritage Program. If approved, this plan will 

 involve additional field surveys, monitoring studies, and 

 preparatioi of a management plan for populations on U.S. 

 Forest Service lands in the state. The Nature Conservancy 

 has established monitoring studies on the Swan River Oxbow 

 Preserve (005) site, to assess population trends and 

 encroachment of Fhalaris eurundinaoea (Reed Canary Grass) 

 into the habitat. 



The habitat in Idaho is managed as a natural area by the 

 present owner. 



In Washington, the Dishman Hills site will essentially be 

 meinaged as a Natural Area Preserve. The Ridgefield National 

 Wildlife Refuge site is manciged as a Research Natural Area. 

 The sites within the Tumbull National Wildlife Refuge are 

 managed primarily as water fcwl habitat. Grazing does occur 

 at seme of the sites, hcwever. Grazing occurs on most, if 

 not all, privately cwned sites (J. Gamon, pers. oorm.). 



