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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (10): 28-39.DOI: 10.11686/cyxb2023014

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Interactive effect of fertilization and cutting on community dynamics and transgressive overyielding effect of grass pasture in the northern Tibetan Plateau

Juan-juan ZHOU1,2(), Wei WEI1,2()   

  1. 1.State Key Laboratory of Highland Barley and Yak Germplasm Resources and Genetic Improvement,Lhasa 850000,China
    2.Institute of Pratacultural Science,Tibet Academy of Agriculture and Animal Husandry Science,Lhasa 850000,China
  • Received:2023-01-06 Revised:2023-02-27 Online:2023-10-20 Published:2023-07-26
  • Contact: Wei WEI

Abstract:

Establishing artificial grassland using native species is an effective measure to restore alpine degraded grassland in the northern Tibetan Plateau. Our objective was to provide the scientific basis for ecological restoration of degraded grassland. This study investigated the dynamics of community fluctuation in sown grassland of three different native species domesticated in the northern part of Tibet: Elymus nutansElymus tangutorum and Poa litwinowiana. We aimed to identify the optimal sowing combination, explore the possibility of transgressive overyielding effect compared with monocultures, net effect of biodiversity, and the response of individual species to fertilization and cutting of mixed-species grassland. The experiment used a split-plot design with 7 sowing combinations as main plots: Monocultures of E. nutans (S1), E. tangutorum (S2) and P. litwinowiana (S3), the combinations of E. nutans+E. tangutorum (M1), E. nutans+P. litwinowiana (M2), E. tangutorum+P. litwinowiana (M3) and E. nutans+E. tangutorum+P. litwinowiana (M4). Fertilization and cutting treatments were applied as sub-plot treatments. The sub-plots set 4 treatments: Fertilization treatment, cutting treatment, fertilization+cutting treatment combination and control (untreated). The plots were planted in 2019 with 60 g·m-2 fertilizer application of (NH42HPO4, cut to 5 cm stubble height. It was found that swards of the different sowing combinations displayed obvious population dynamic changes through the growing season. Aboveground biomass peaked on September 20th (the end of growing season), and E. nutans was the dominant species of mixtures. The underground biomass accumulation reached its maximum value on August 20th (booting stage); The underground biomass of treatment M4 was the highest (669.61 g·m-2). The combination of E. nutans+E. tangutorum+P. litwinowiana (M4) had the highest productivity. A positive interaction between fertilization and cutting treatments resulted in high yield (3190.83 g·m-2) in the fertilization+cutting treatment combination. Therefore, the mixed sowing of E. nutans+E. tangutorum+P. litwinowiana with fertilization and cutting is the recommended methodology for the establishment of sown grassland in the northern Tibetan Plateau. When tested using natural log response ratio (LNRR) analysis, E. nutans had the strongest competitiveness, followed by P. litwinowiana and E. tangutorum. The relative yield totals of M1, M2, M3 (control and cutting treatments) and M4 were all greater than 1.0, and thus all had over yielding compared to the respective monocultures. In M4, M1 (control and cutting treatments), M2 (cutting, fertilization and fertilization+cutting treatments), the complementary effect and selection effects jointly contributed to the over yielding, while in M1 (fertilization and fertilization+cutting treatments), M2 (control treatment) and M3 (control and cutting treatments), only the complementary effect was important and dominated the over yielding.

Key words: artificial grassland, native species, fertilization and cutting, community dynamics, transgressive overyielding effect, the northern Tibetan Plateau