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Role of Seed Bank in Establishment of Single and Mixed-Sowing Artificial Grasslands of Tibetan Plateau

Ma Z., Zhang C., Zhou H.-K., Yao B.-Q., Zhao X.-Q.

Polish Journal of Ecology

2017

Vol. 65, nr 4

334--344

Artificial grassland establishment is one of the fastest and most effective ways to restore the productivity of degraded grasslands. Little is known about the effect of different types of artificial grassland establishment (i.e., single- and mixed-sowing grassland establishment with perennial grasses) on soil seed bank in degraded grassland ecosystems. Single-sowing population of a high yield species usually has a great standing biomass causing shading that may inhibit germination of seeds in soil seed bank. Thus, we hypothesized that there is higher species richness and seed density in the soil seed bank of single-sowing than mixed-sowing grasslands. Here, we investigated the soil seed bank in four-year old single-sowing and mixed-sowing and control (degraded) grasslands on the Qinghai-Tibetan Plateau. We found that the autumn seed bank of mixed-sowing grasslands had lower species richness and seed density than single-sowing grasslands, while the summer soil seed bank (persistent seed bank) showed little differences. There were differences in biomass among the three grasslands (single-sowing > mixed-sowing > control), but there was no differences in species richness of vegetation. In sum, our results of the autumn seed bank support our hypothesis. Greater above-ground biomass in single-sowing grasslands could generally cause low light availability preventing seeds in soil from germinating and support more seed output, which both may indirectly or directly result in the relatively higher species richness and seed density in the soil seed bank. Our results also suggest that artificial grasslands usually returning to native grasslands in terms of production and species composition after several years is likely due to stability of the persistent soil seed bank.

Stable carbon and nitrogen isotopes reveal the food diet of Tibetan antelope Pantholops hodgsoni (Abel 1826) in Kekexili Nature Reserve (China)

Sun P., Yu H.-H., Zhao X.-Q., Wang D.-H.

Polish Journal of Ecology

2013

Vol. 61, nr 2

365--371

The stable isotope technique has been widely used to infer the dietary ecology of a range of animal species. The δ13C technique provides a valuable tool for researchers when designing pastures for dual environmental and production purposes. Tibetan antelope, Pantholops hodgsoni (chiru), is endemic species to the high-altitude Qinghai-Tibet Plateau of western China – Kekexili Nature Reserve area. The aim of this study was to identify the food diet of Tibetan antelope among plants with C3 and C4 photosynthetic pathways. Faeces and plant samples were collected at the Kekexili Nature Reserve (KNR, 34°19’ ~ 36°16’N, 89°25’ ~94°05’E) in Qinghai Province, China. Stable isotope values of carbon and nitrogen of faeces and plant samples were measured under EAMS (element-analysis meter and spectrometer) conditions. Enrichment and food content ratio were calculated according to previous research methods to determine the relative importance of plant sources in the food diet of Tibetan antelopes. The results indicate that faecal samples provided the most convenient and uninjurious sources to predict the food diet and that C3 plants were selected as the food by chiru. Dualisotope multiple-source mixing model suggested that the food content of antelope is including Gramineae, Cyperaceae, Compositae, Leguminosae, and Cruciferae. An understanding of what chiru selects allows for development of appropriate grazing and protecting strategies, especially in fragile ecosystem. According to our knowledge, this is the first essay to reveal the food diet of chiru with stable isotope analysis method.