The role of refugia in the recolonization of streams devastated by the 1980 eruption of Mt. St. Helens
Streams normallv consist of mosaics of habitat patches (Pringlc et al. I9BB). each of l,hich provides cronditions and rcsourccs suitable for different Ipes of lliola. We t1''picalh intlude rilfles. pools. and runs as stream habitais. but these tlpes ofhabtats can bc cithcr dividcd or combined dependng on the scale of interest. In fact. slream hab;taLs can be delined at -"everal spatial scales (Table 1). Considcring the l'ay stream environments van' at different spatial scales leads to insiglrt-s regarding the factofs that promotc and maintain biodiversitr in srreatn ecosYstems. In streams. environmental heterogeneitv begets biological divelsitl. Furthermorc" individual patcics embedded lithin complex environrnenls ofLen act us rcfugia from disturbance and can strongl,v influencc lhc ratc of rccoven in streams follo$.ing disturbance. Rccausc of thc patch_r nature of stleam habitats, even catastrophic distulbances r.ill selclom eliminate biota liom an entire strearn. Corsequen! h. thu' h.rhit.rt p.rl, hos lh.rl Jre cilher rr.-i.lflnl lo di-qturbance or simpll_ escape denudaLion bv chance can act a-s sources of colonists fiom uhich disturbed habitlts rue subsequendv recolonized. The presence of rcfugia can therefore confer ecological resiJience to sLream ecoslslems as a lrholc.
Hawkins, C.P. and J.R. Sedell. 1991. The role of refugia in the recolonization of streams devastated by the 1980 eruption of Mt. St. Helens. Northwest Science 64:271-274