Effects of herbaceous competition on high growth of regeneration seedlings of Betula platyphylla and Acer mono
Herbaceous competition has a significant ecological effect on forest regeneration and is an important limiting factor for the growth stage of regenerated seedlings.However,the theoretical understanding of the mechanism of the herbaceous competitive effect remains limited.In this study,Betula platyphylla and Acer mono were used as experimental objects in a pot experiment.Four types of competition(non-competition,full competition,above-ground competition,and below-ground competition),four soil nutrient gradients(0,8,16,and 32 g/m2),and two nutrient distribution levels(homogeneous and heterogeneity)were set up,and each treatment was repeated eight times.Linear decomposition of the herbaceous competition effect was realized using a linear model.The relative importance of the contribution rate of each competition effect component was accurately measured and the mechanism of herbaceous competition on seedling height growth under different soil nutrient conditions was revealed based on structural equation modeling.The results showed that herbaceous competition inhibited seedling growth at all succession stages(P＜0.05).The contribution rates of above-ground competition,underground competition,and their interaction were 40％-60％,20％-30％,and 20％-30％,respectively.Different soil nutrient concentrations and distributions significantly affected the contribution rates.Herbaceous plants mainly affected the nutrient uptake capacity of B.platyphylla seedlings(0.62)and the photosynthetic capability of A.mono seedlings(0.74).This affected their growth.Nutrient uptake capacity was more important than photosynthetic capacity under high concentrations or heterogeneous soil nutrient distributions.The herbaceous competition effects of the two ecological learning tree species differed significantly(P＜0.05).The results showed that herbaceous competition and soil nutrients profoundly affected the height growth of regeneration seedlings by affecting soil nutrient uptake and photosynthesis of B.platyphylla and A.mono seedlings.Notably,the mechanism of herbaceous competition on height growth of regeneration seedlings is an important ecological mechanism for maintaining the height growth of seedlings.
competition mechanismregeneration seedlingbiomassmorphological indexstructural equation model
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