12 research outputs found
Potential effects of sea-level rise on plant productivity: species-specific responses in northeast Pacific tidal marshes
An integrated analysis of the effects of past land use on forest herb colonization at the landscape scale
Balanced Sediment Fluxes in Southern California’s Mediterranean-Climate Zone Salt Marshes
Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salt marsh (Seal Beach) and a less modified 1-km2 marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1–2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu’s dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits
Urban areas as hot-spots for introduced and shelters for native isopod species
Isopod assemblages were studied in Budapest, capital of Hungary.
The analyses of literary and field data revealed a high species
richness (28 species), compared to the total species number (57)
in Hungary. Habitats characteristics for the city were
categorized as native forests, urban forests, gardens of Buda,
gardens of Pest, public parks, densely built-up areas and
botanical gardens. We hypothesized that isolated and diverse
habitat patches in the city matrix of Budapest support the
introduction and establishment of exotic species and the
survival of native ones. The composition of assemblages varied
among sampling sites, but were characteristic for the biotope
categories. We concluded that forests, parks and gardens play an
important role in the survival of native isopod populations.
Species numbers were highest in the gardens of Buda and in the
botanical gardens (both 17 species). The overall presence of
cosmopolitan and disturbance-tolerant species indicates an
ongoing homogenization process.
Key-words: soil fauna, woodlice, urban biodiversity, species
introduction, taxonomic uniformit