Allelopathy effects of invasive alien Ageratina adenophora on native shrub species of chir pine forest in the central Himalaya, India

ABSTRACT

Ageratina adenophora Spreng. is one of the most troublesome invasive species that has invaded various forest ecosystems in the central Himalaya. The chir pine (Pinus roxburghii Sarg.) forests in the region facing a high risk of invasion and loss understory diversity of native species. The present study comprehends the allelopathy effect of the invasive species A. adenophora residues bioassay (extract) and soil amendment against two co-occurring native shrubs viz Berberis asiatica Roxb. Ex DC. and Rubus ellipticus Sm. in a laboratory and natural forest conditions. Results revealed that a higher concentration (4% and 8%) of A. adenophora leaf, root and shoot extract have significantly inhibited (23% to 76%) and low concentration (1%) did not inhibit the seed germination, root and shoot length of B. asiatica and R. ellipticus. Furthermore, 8% (w/w) A. adenophora residue (leaf, root and shoot) amendments with the natural soil also showed significant inhibition effects (13% to 37%) on seedling growth and biomass of both the test species. Weekly A. adenophora leaf residue amendment showed higher inhibition in shoot elongation than root and shoot amendment during the experiment period. The study demonstrated that A. adenophora extract and residue amendment have strong allelopathic effects on woody shrub species and indicating allelopathy played important role in the successful establishment and rapid spread of A. adenophora in the understory of chir pine forests.

KEYWORDS:

• Allelopathy
• woody shrubs
• A. adenophora residue extract
• A. adenophora residue amendment
• seedling growth

Acknowledgments

The authors acknowledge the University Grant Commission (UGC) and DST-PURSE, India, for providing financial support (Ref. no. 22/06/2014(i)EU-V). The authors are grateful to the Vinod Negi for their help in the field experiment and Rajendra Kumar Joshi for help in laboratory experiment. The authors are thankful to the editor and two anonymous reviewers for their valuable comments and suggestions which helped in improving the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Geolocation information

The study site was located at Chanfi village (29° 22ʹ 22.4” N 79° 34ʹ 33.9” E) in Nainital district, Uttarakhand, India.

Additional information

Funding

This work was supported by the Department of Science and Technology, Ministry of Science and Technology [DST Purse]; University Grants Commission [Student Support].