Plant interactions modulate root litter decomposition and negative plant-soil feedback with an invasive plant
Invasive plants often modify soil biota to benefit their own fitness over native species, and create a positive plant-soil feedback (PSF). Rhizosphere effect (RE), the alterations of decomposition processes by living roots and associated rhizodeposits, may act as a mechanism that contributes to the positive PSF via accelerating litter decomposition and subsequent soil nutrient turnover. However, the relative effects attributable to litter quality versus plant composition and edaphic conditions on RE remain unclear.
A reciprocal translocation decomposition experiment was conducted in a screenhouse with root litter from an invasive (Flaveria bidentis) and a native species (Bidens maximowicziana) in two types of soils (one dominated by the invasive species and another by the native species) with four plantings (two monocultures, one mixture with both species, and one without living plants). We examined the performance of invasive and native species responses to different soils (PSF) and quantified the RE on litter decomposition.
PSF and RE were dependent on whether focal species grew in the monocultures or mixture, and interspecific competition ameliorated negative PSF of F. bidentis when it competed with a weaker competitor. All RE values associated with B. maximowicziana litter under the monocultures were positive, whereas F. bidentis litter exhibited neutral to negative REs, mainly depending on the soil type examined. The RE values in the invaded soil were significantly greater than those in the native soil under the monocultures. However, mixture planting tended to decrease REs on decomposition, which in turn feedback to host plant by affecting soil N availability and microbial composition.
Our study showed that innate differences between the two litters in terms of their decomposability and edaphic conditions are likely to exert a much greater impact in controlling litter decomposition. Importantly, rhizosphere-mediate belowground process has the potential to be an important contributor to plant-interaction outcomes.
KeywordsInvasive plant Root litter decomposition Rhizosphere effect Plant interaction Plant-soil feedback
We are grateful to four anonymous reviewers for their valuable comments, Xiaohang Bai and Weidong Zhang from the Institute of Applied Ecology, CAS (Shenyang) for their statistical suggestions. We also appreciated the insightful discussion with Professor Biao Zhu from Peking University. This study was funded by the Natural Science Foundation of Tianjin (12JCQNJC09800) and the Special Fund for Agro-scientific Research in the Public Interest (200803022, 201103027).
Compliance with ethical standards
The authors declare that they have no competing interests.
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