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101.
How could sympatric megaherbivores coexist? Example of niche partitioning within a proboscidean community from the Miocene of Europe 总被引:1,自引:1,他引:0
Although low in diversity, megaherbivores (mammals weighting over 10(3) kg) and especially proboscideans have a powerful impact on the structure and dynamics of present-day ecosystems. During the Neogene (23 to 2.6 Ma) of Europe, the diversity and geographic distribution of these megaherbivores was much greater. Nonetheless, their role in past ecosystems is unclear. Nutrition is one of the main bonds between organisms and their environment. Therefore, the ecology of organisms can be inferred from their dietary habits. The present study is aimed at characterizing the feeding habits of diverse megaherbivores through dental microwear analyses. This method was applied on cheek teeth of three sympatric species of proboscideans from the middle/late Miocene of the Molasse Basin in Southern Germany: Gomphotherium subtapiroideum, Gomphotherium steinheimense, and Deinotherium giganteum. The microwear signatures are significantly different between these taxa, suggesting differences in feeding habits and ecological niches within a woodland environment. D. giganteum probably browsed on dicotyledonous foliages whereas the two species of gomphotheres were neither strict grazers nor strict browsers and instead probably fed on a large spectrum of vegetal resources. The differences of occlusal molar morphology between the two gomphotheres are supported by the dental microwear pattern. Indeed, G. subtapiroideum probably ingested more abrasive material than G. steinheimense. Thus, our results suggest that these proboscideans did not compete for food resources. 相似文献
102.
The Influence of Two‐Stage Ditches with Constructed Floodplains on Water Column Nutrients and Sediments in Agricultural Streams
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Robert T. Davis Jennifer L. Tank Ursula H. Mahl Sarah G. Winikoff Sarah S. Roley 《Journal of the American Water Resources Association》2015,51(4):941-955
The two‐stage ditch is a novel management practice originally implemented to increase bank stability through floodplain restoration in channelized agricultural streams. To determine the effects of two‐stage construction on sediment and nutrient loads, we monitored turbidity, and also measured total suspended solids (TSS), dissolved inorganic nitrogen (N) species, and phosphorus (P) after two‐stage ditch construction in reference and manipulated reaches of four streams. Turbidity decreased during floodplain inundation at all sites, but TSS and P, soluble reactive phosphorus (SRP) and total phosphorus (TP) decreased only in the two‐stage ditches with longer duration of inundation. Both TSS and TP were positively correlated within individual streams, but neither were correlated with turbidity. Phosphorus was elevated in the stream to which manure was applied adjacent to the two‐stage reach, but not the reference reach, suggesting that landscape nutrient management plans could restrict nutrient transport to the stream, ultimately determining the efficacy of instream management practices. In addition, ammonium and nitrate decreased in two‐stage reaches with lower initial N concentrations. Overall, results suggest that turbidity, TSS, and TP were reduced during floodplain inundation, but the two‐stage alone may not be effective for managing high inorganic N loads. 相似文献