Autecological studies of Drosera linearis, a threatened sundew species

The linear-leaf sundew has been extirpated from several stations at the southern edge of Its range. Cedarburg Bog is believed to harbor the largest of the remaining southern colonies of this species. Drosera linearis has a lower reproductive output at Cedarburg Bog than at other sites, and produces fewer seeds per plant than the three sundew species which share its range. The population studied at Cedarburg Bog declined in population size and reproductive output from 1980 to 1982, and revealed characteristics associated with high rates of local extinction. Populations experienced rapid turnover of individuals, and population size was closely coupled to the size of the previous year\u27s seed crop. Sustained flooding in the flarks of the patterned fen further decreased population stability. The species may have persisted at Cedarburg Bog because the patterned fen is sufficiently large to allow the recolonization rate to keep pace with the rate of local extinction

Coupling groundwater and riparian vegetation models to assess effects of reservoir releases

Although riparian areas in the arid southwestern United States are critical for maintaining species diversity, their extent and health have been declining since Euro-American settlement. The purpose of this study was to develop a methodology to evaluate the potential for riparian vegetation restoration and groundwater recharge. A numerical groundwater flow model was coupled with a conceptual riparian vegetation model to predict hydrologic conditions favorable to maintaining riparian vegetation downstream of a reservoir. A Geographic Information System(GIS) was used for this one-way coupling. Constant and seasonally varying releases from the dam were simulated using volumes anticipated to be permitted by a regional water supplier. Simulations indicated that seasonally variable releases would produce surface flow 5.4-8.5 km below the dam in a previously dry reach. Using depth to groundwater simulations from the numerical flow model with conceptual models of depths to water necessary for maintenance of riparian vegetation, the GIS analysis predicted a 5- to 6.5-fold increase in the area capable of sustaining riparian vegetation

Multitaxonomic Diversity Patterns along a Desert Riparian–Upland Gradient

Riparian areas are noted for their high biodiversity, but this has rarely been tested across a wide range of taxonomic groups. We set out to describe species richness, species abundance, and community similarity patterns for 11 taxonomic groups (forbs & grasses, shrubs, trees, solpugids, spiders, scarab beetles, butterflies, lizards, birds, rodents, and mammalian carnivores) individually and for all groups combined along a riparian–upland gradient in semiarid southeastern Arizona, USA. Additionally, we assessed whether biological characteristics could explain variation in diversity along the gradient using five traits (trophic level, body size, life span, thermoregulatory mechanism, and taxonomic affiliation). At the level of individual groups diversity patterns varied along the gradient, with some having greater richness and/or abundance in riparian zones whereas others were more diverse and/or abundant in upland zones. Across all taxa combined, riparian zones contained significantly more species than the uplands. Community similarity between riparian and upland zones was low, and beta diversity was significantly greater than expected for most taxonomic groups, though biological traits explained little variance in diversity along the gradient. These results indicate heterogeneity amongst taxa in how they respond to the factors that structure ecological communities in riparian landscapes. Nevertheless, across taxonomic groups the overall pattern is one of greater species richness and abundance in riparian zones, coupled with a distinct suite of species

Herbaceous exotics in Arizona's Riparian Ecosystems

Desert Plants is published by The University of Arizona for the Boyce Thompson Southwestern Arboretum. For more information about this unique botanical journal, please email the College of Agriculture and Life Sciences Publications Office at [email protected]

MORTALITY AND AGE OF BLACK COTTONWOOD STANDS ALONG DIVERTED AND UNDIVERTED STREAMS IN THE EASTERN SIERRA NEVADA, CALIFORNIA

Volume: 39Start Page: 205End Page: 22

RESPONSE OF SALIX LASIOLEPIS TO AUGMENTED STREAM FLOWS IN THE UPPER OWENS RIVER

Volume: 39Start Page: 224End Page: 23

SEED PRODUCTION AND SEEDLING ESTABLISHMENT OF A SOUTHWEST RIPARIAN TREE, ARIZONA WALNUT (JUGLANS MAJOR)

Volume: 50Start Page: 47End Page: 5