黄土高原撂荒地白草种群生长动态OA

Pennisetum centrasiaticum is a typical pioneer species on the abandoned farmlands of the Loess Plateau.Based on ten years of continuous field monitoring data,the responses of P.centrasiaticum population dynamics to the abandonment duration and climatic factors were analyzed.The results showed that with increas-ing abandonment duration,the plant height and canopy diameter of P.centrasiaticum decreased significantly by 2.26 cm and 6.01 cm,respectively,after ten years of abandonment compared to the first year.Reproductive branch density and tiller density exhibited an initial increase followed by a decline,in which tiller density peaked in the fifth year of abandonment.Tiller density reduced by 2.31 tillers/m2 in the ten years of abandonment com-pared to the peak.Seedling density decreased by 4.00 plants/m2 after ten years abandonment compared to the first year.Population density and aboveground biomass showed significant decreasing trend with abandonment duriation,with annual average reductions of 0.82 plants/m2 and 1.92 g/m²,respectively,by the tenth year rela-tive to the first year.The abandonment duration was identified as the dominant factor affecting plant growth,reproductive characteristics,and biomass accumulation of P.centrasiaticum populations,independently explain-ing 33%to 79%of the variation in each of the indictors.Structural equation modeling further revealed that the abandonment duration not only directly suppressed the aboveground biomass of P.centrasiaticum,but also exerted an indirect negative effect by limiting seedling density.Furthermore,the abandonment duration indi-rectly reduced the proportion of P.centrasiaticum aboveground biomass within the community by suppressing plant height,canopy diameter,seedling density,and population density.