Abstract:
【Objective】 This study aimed to investigate the feedback regulation of soil legacy effects within
Alternanthera philoxeroides-invaded habitats on itself and the native coexisting species
Digitaria sanguinalis， so as to provide theoretical basis for predicting the invasion trends of
Alternanthera philoxeroides under environmental changes and implementing biological substitution. 【Method】 Soil samples were collected from habitats seriously invaded by
Alternanthera philoxeroides in four provinces （regions） of China， including Jiangxi， Hunan， Guangxi， and Guangdong. The three-factors potted experiment was conducted， which including the soil treatment （control treatment， feedback treatment （adding soil within invaded habitats）， planting method （mono and mixed culture）， and species trait （
Digitaria sanguinalis，
Alternanthera philoxeroides）， to examine the effects of soil within invaded habitats on the morphological trait， biomass， nutrition， and photosynthetic fluorescence of
Alternanthera philoxeroides and
Digitaria sanguinalis. 【Result】 The maximum stem length， content of total carbon and total nitrogen in
Digitaria sanguinalis were significantly （
P<0.05， the same below） or extremely significantly （
P<0.01， the same below） higher than those in
Alternanthera philoxeroides， while the root area， total biomass， shoot biomass， root biomass， root-shoot ratio， minimum fluorescence （
F0）， maximum fluorescence （
Fm）， and photochemical quenching coefficient （qP-Lss） of
Alternanthera philoxeroides were significantly or extremely significantly higher than those of
Digitaria sanguinalis. Compared with the control treatment， feedback treatment led to extremely significant decrease in the maximum stem length， root length， root area， and leaf area of the entire stu-died plants， and caused a higher decrease in the root length of
Alternanthera philoxeroides than that of
Digitaria sanguinalis in mixed cultures. Feedback treatment led to significant or extremely significant decrease in the total biomass， shoot biomass， and root biomass of the entire studied plants， caused an extremely significant decrease of 48.28% in the root-shoot ratio of
Digitaria sanguinalis and an extremely significant increase of 20.10% in that of
Alternanthera philoxeroides. Feedback treatment led to an extremely significant increase of 13.79% and 148.00% in the total carbon of
Digitaria sanguinalis and
Alternanthera philoxeroides respectively. Feedback treatment led to significant increase in the maximum light quantum efficiency （
Fv/
Fm） of the entire studied plants and the steady-state light actual quantum efficiency （QY-Lss） of
Digitaria sanguinalis， while caused significant decrease of 45.40% and 32.18% in
F0 and
Fm of
Alternanthera philoxeroides in mixed cultures respectively. 【Conclusion】 Soil within
Alternanthera philoxeroides-invaded habitats on large scale weakens the morphology and biomass of itself and
Digitaria sanguinalis， and interspecific competition intensifies the negative feedback of soil within invaded-habitats on photosynthetic fluorescence of
Alternanthera philoxeroides. Thus， when the native species
Digitaria sanguinalis exists in communities， soil within invaded habitats may not be conducive to the secondary invasion of
Alternanthera philoxeroides， and the artificial planting of
Digitaria sanguinalis in invasion areas can be considered as a method for substitutive control of
A.
philoxeroides.
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