Reproductive characteristics of a Populus euphratica population and prospects for its restoration in China

• Published in: PloS one 2012-07, Vol.7 (7), p.e39121-e39121
• Main Authors: Cao, Dechang, Li, Jingwen, Huang, Zhenying, Baskin, Carol C, Baskin, Jerry M, Hao, Peng, Zhou, Weilei, Li, Junqing
• Format: Article
• Language: English
• Subjects: Agriculture; Arid regions; Biology; Canals; Channeling; China; Dispersal; Dispersion; Distilled water; Ecosystem biology; Ecosystems; Education; Environmental changes; Environmental economics; Environmental restoration; Failure; Floods; Forest management; Forestry; Forests; Germination; Germination - physiology; Grazing; Groundwater; Laboratories; Land management; Ovis aries; Plant Roots - physiology; Populus - physiology; Populus euphratica; Populus nigra; Rain; Rainfall; Regeneration; Reproduction - physiology; Restoration; Riparian environments; River banks; Rivers; Seed dispersal; Seed germination; Seedlings; Seeds; Seeds - physiology; Sheep; Silt; Soil sciences; Systems analysis; Tamarix ramosissima; Temporal variability; Trees - physiology; Valuation; Vegetation; Water consumption; Water shortages; Water use
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0039121

Populus euphratica is a dominant tree in riparian ecosystems in arid areas of northwest China, but it fails to regenerate in these systems. This study evaluates causes for the failure of sexual and asexual regeneration of this species in the wild. P. euphratica disperses as many as 85743 seeds/m(2) during summer, and the seeds germinate to 92.0% in distilled water and to 60.8% on silt. However, very few seeds (3.6%) can germinate on unflooded soil. The seed-rain season is prolonged by temporal variability in seed dispersal among individuals, which ensures that seedling emergence can occur during favorable conditions (i.e., floods and rainfall). As a result of water shortage and river channeling due to water usage and altered river flows, there are no safe sites on river banks for seed germination, which has led to the failure of P. euphratica to regenerate from seed. Root suckers of P. euphratica were present in 86% of the forest gaps investigated. However, extensive grazing has destroyed many of them and thus has reduced this form of regeneration. This research suggests that human activities are resulting in the failure of P. euphratica to regenerate. Changes in land management such as reduced use of concrete canals in Populus forests and/or reduced sheep grazing in these areas may promote their regeneration.