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A Comparative Study on Diaspore Weight and Shape of 43 Species at the Alpine Meadow in the Source Region of Three Rivers

Author: Update time: 07-20-2009 Printer Text Size: A A A
We studied the diaspore weight and shape of 43 species (13 seeds, 30 fruits) in the Alpine meadow.15 species (accounting for 35%) had a diaspore weight less than 1 mg, and meanwhile close to sphericity (variance less than 0.09). Previous studies have shown that morphological characteristics of diaspore were closely related to longevity of soil seed bank, thus these species might have persistent soil seed bank, and adapt to disturbance. Although diaspore weight and shape might be related to life form of plants, the weight and shape differences of diasporas were distinct between annuals and perennials (P<0.05), and the diaspores of perennials were weighter, flatter and longer. There was an evident shape difference of diaspores between palatable herbages and forbs (P<0.01), and the diaspores of forbs were weighter, but the diaspores of palatable herbages were flatter and longer. Seeds were closer to sphericity in comparison with fruits(P<0.01. All the diaspores of Compositae and Gramineae and Sedges species were flat and elongated (variance more than 0.06), and the diaspore weight of Compositae species was evidently larger than that of Gramineae and Sedges species(P<0.05). Therewfore, study that  whether they were easier to form persistent seed bank or not is needed.The appendages of diaspores played an important role in dispersal and establishment, the diaspores of 60% Compositae species had pappuses, they might be dispersed by wind easily, and the diaspores of 88.9% Gramineae species had awns, these species were not likely to be dispersed. Nevertheless, the investigation of diaspore dispersal and soil seed bank persistence is needed before we could fully understand the ecological significance of diaspore morphology.
Northwest Institute of Plateau Biology, CAS
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