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Society for Conservation Biology: 2002 Annual Meeting

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Society for Conservation Biology: 2002 Annual Meeting


Society for Conservation Biology 16th Annual Meeting July 14-July 19 2002
co-hosted by DICE and the British Ecological Society


Abstracts for Community Ecology
Session One

Wednesday 17th July, 13.30 - 15.00, Grimond Lecture Theatre 2

Chair: Bruce Baker




(BLOCK CAPITALS indicate the presenting author)


13.30 - 13.45
WILCOX, CAROLYN S., Robert S. Nowak, and Joseph W. Ferguson. University of Nevada, Reno, Environmental and Resource Science, Mail Stop 370, Reno, Nevada 89557-0013, USA, <cwilcox@unr.nevada.edu>, <carolynwilcox@juno.com>.

FINE ROOT GROWTH DYNAMICS OF MOJAVE DESERT SHRUBS AS RELATED TO SOIL MOISTURE AND MICROHABITAT PATCHES

Desert plants are often exposed to long periods of drought and have developed distinct water uptake and conservation strategies to promote growth and survival under variable precipitation patterns. The ability to extract water in a highly effective manner has led to the inclusion of desert vegetation in landfill cap design. Although our understanding of desert water relations and root growth would aid in landfill cap design, few studies have directly investigated these topics. This field study addresses the relationship between active fine root length (mm), soil moisture (%), and microhabitat patches (interspace and canopy) for the Mojave Desert shrubs, Ambrosia dumosa and Ephedra nevadensis. Minirhizotron and neutron probe tubes were used to measure fine root lengths and soil moisture, respectively, in the interspaces and under the canopies of selected shrub-dominated communities. Soil moisture was significantly correlated to the root lengths for both Ambrosia and Ephedra. Additionally, root lengths were significantly greater under the canopy relative to the interspace for both shrub species. These results will have direct applications to the use of desert shrubs in landfill developments and will increase our understanding of physiological and ecological interactions involving Mojave Desert shrubs for potential conservation strategies.

13.45 - 14.00
GUNNARSSON, BENGT, Mikael Hake and Svante Hultengren. Department of Applied Environmental Science, Göteborg University, Box 464, SE 405 30 Göteborg, Sweden, <bengt.gunnarsson@miljo.gu.se> (BG), Grimsö Wildlife Research Station, Department of Conservation Biology, Swedish University of Agricultural Sciences, SE 730 91 Riddarhyttan, Sweden (MH), Naturcentrum, C W Borgs väg 4, SE 444 31 Stenungsund, Sweden (SH).

A RELATIONSHIP BETWEEN SPECIES RICHNESS OF SPIDERS AND LICHENS

We tested the hypothesis that species richness of spiders and foliose and fruticose lichens is positively related in spruce, Picea abies, canopies and investigated whether the number of spider and lichen species are affected by forest management in mid-Sweden. Modern forestry has a major impact on ecological systems in boreal forests, and its effects on biodiversity within many taxa need to be examined. High species richness of lichens may increase the structural complexity of the microhabitat on spruce branches and bring a higher species richness also in the spider community. In six areas, spruce branches were sampled in old-growth and managed boreal forest stands, respectively. Analyses revealed that forest management did not affect the species richness of spiders. The number of lichen species was, however, slightly higher in the managed forests. There was a significant covariation between species richness of lichens and spiders, and the hypothesised positive relationship was confirmed by separate analyses for each area. We conclude that species richness of lichens and spiders are related on spruce branches for functional reasons. This information may be important for conservation biologists, as it provides a "short-cut" for assessing biodiversity in boreal forests.



14.00 - 14.15
CORDEIRO, NORBERT J., Department of Biological Sciences (m/c 066), University of Illinois-Chicago, 845 W. Taylor Street, Chicago, IL 60607, USA, <ncorde1@uic.edu>.

FRAGMENTATION NEGATIVELY IMPACTS DISPERSAL AGENTS AND THEIR DEPENDENT PLANTS IN AN AFRICAN FOREST

Tropical forest fragmentation is a well known agent of biotic extinctions, and yet little is known about how this process impacts plant and animal interactions. If seed dispersal agents decline for tree species in fragments of decreasing area, one would expect corresponding declines in these dependent trees. These predictions were tested in the East Usambara Mountains, Tanzania, an area with 21% floral endemism. Trees > 10 cm were enumerated in 20 x 20 m randomly placed quadrats in 13 fragments ranging in size from 0.5 to 3500 ha and isolated for > 80 years. A total of 62 animal-dispersed tree species were identified, of which 18 were endemics. Regressions of the log fragment area and log number of species of all animal-dispersed (R2=0.789, p<0.0001) and endemic animal-dispersed (R2=0.377, p<0.05) species exhibited a significant negative relationship with area. Censuses of frugivores spanning 16 months in the same fragments showed that these species declined significantly with decreasing area (R2=0.64, p<0.001). Animal-dispersed tree species, including endemics, decrease as a probable result of losing dependent dispersal agents. Other explanations, such as increased seed and seedling predation and pollinator limitation, may also play a role.



14.15 - 14.30
BÁLDI, András. Animal Ecology Research Group, HAS, Hungarian Natural History Museum, Ludovika tér 2, Budapest 1083 , Hungary, <baldi@ludovika.nhmus.hu>.

THE LOSS OF SPECIES AND INDIVIDUALS MAY DESTROY METACOMMUNITY COMPOSITION

The nested subsets pattern of community composition is common in nature, wherein less species-rich local communities are subsets of richer communities. Nestedness analyses are based on occurrence data, and the effects of distribution of abundance among species have not previously been studied. In a step-by-step procedure, I excluded the rarest and the most abundant species of four example metacommunities (birds, beetles, butterflies, orthopterans), and correlated the changes of nestedness with the loss of species and individuals. Nestedness declined rapidly in orthopterans and butterflies. The loss of 15-25% of the rarest species led to non-nested metacommunities. The loss of <23% of individuals of the rarest species in all groups resulted in random composition. Excluding less than one third of the most abundant species in all groups resulted in non-nested metacommunities. The loss of individuals of the abundant species was >58% to reach non-nested pattern for all the four groups. Therefore, the decline in the number of species and/or individuals may destroy the original metacommunity structure, and resulted in random species composition. It has important message for conservation, showing that the effects of population extinctions and declines may have important long-term effects on the predictability of species composition of metacommunities.



14.30 - 14.45
SU SU, DAW and John B. Sale. Zoology Department, Yangon University, Yangon, Myanmar, <susurosie@mptmail.net.mm> (SS) and Biodiversity Conservation Consultant, Fach Gynan, Moelfre, Oswestry, SY10 7QP, UK (JBS).

DYNAMICS OF A SMALL CARNIVORE COMMUNITY IN MYANMAR: SOME PRELIMINARY FINDINGS

The study investigates the dynamics of a typical small carnivore community in a reserve in lower Myanmar, identifying any threats to survival of the five species, namely Palm Civet (Paradoxurus hermaphroditus), Small Indian Civet (Viverricula indica), Crab-eating Mongoose (Herpestes urva), Jungle Cat (Felis chaus) and Leopard cat (F. bengalensis). In addition to observation of individuals and sign (tracks, scats), methodology includes camera trapping and radio-tracking. Food availability is determined by phenology studies, observation and trapping of potential prey species. Scat analysis provides quantitative data on actual diets. Results show Palm Civets as being very common and Small Indian Civets as relatively common (ratio of respective numbers 7.8:1). Sparse data indicate that Mongooses, Jungle Cats and Leopard Cats are uncommon. While the two civets eat mainly fruit and insects, the three rarer species are primarily predators on small vertebrates and, as such, occasionally attack domestic poultry, resulting in their persecution by people residing near the reserve. Greater protection is essential for mongooses and small cats if these species are to survive in populated areas of the country.



14.45 - 15.00
BAKER, BRUCE W., Heather C. Ducharme, David C. Mitchell, Thomas R. Stanley, and H. Raul Peinetti. US Geological Survey, Midcontinent Ecological Science Center, Fort Collins, CO 80525-3400, USA, <bruce_baker@usgs.gov> (BWB, HCD, DCM, TRS, HRP), Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80523-1499, USA and Facultad de Agronomia, Universidad Nacional de La Pampa, Santa Rosa, Argentina (HRP).

INTERACTION OF BEAVER AND ELK AS A MECHANISM OF DECLINING WILLOW IN ROCKY MOUNTAIN NATIONAL PARK

Populations of beaver, Castor canadensis, and willow, Salix spp., have decreased coincident with increased populations of elk, Cervus elaphus, in Rocky Mountain National Park (RMNP). We experimentally tested the effects of elk browsing on regrowth of simulated beaver-cut willow inside and outside 5 elk exclosures and found intense elk browsing produced plants of low vigour that were small and hedged with a high percentage of dead stems. In contrast, regrowth of protected plants had high vigour and were large, highly branched, and leafy with a low percentage of dead stems. We also compared use of woody stems in food caches and dams with nearby unused stems and found that beaver selected stems that had a lower percentage of leaders browsed by elk. We conclude that if beaver cut tall willow, and intense elk browsing suppresses regrowth, then the interaction of beaver and elk may function as a mechanism of declining riparian willow. Further, we speculate that intense elk browsing may decrease the suitability of willow as winter beaver food, increase willow mortality (directly or indirectly through loss of beaver), alter willow community structure, and increase elk carrying capacity by conversion of beaver-wetland to upland-meadow.