Comparative effects of soil resource availability on physiology and growth of Scotch broom (Cytisus scoparius) and Douglas-fir (Pseudotsuga menziesii) seedlings

FOREST ECOLOGY AND MANAGEMENT

卷:453

Article

Carter, David R.¹  Slesak, Robert A.²  Harrington, Timothy B.³  D'Amato, Anthony W.⁴ 

[1] Virginia Polytech Inst & State Univ, Dept Forest Resources & Environm Conservat, 228G Cheatham Hall, Blacksburg, VA 24060 USA

[2] Univ Minnesota, Dept Forest Resources, 1530 Cleveland Ave N, St Paul, MN 55108 USA

[3] US Forest Serv, USDA, Pacific Northwest Res Stn, 3625 93rd Ave Southwest, Olympia, WA 98512 USA

[4] Univ Vermont, Rubenstein Sch Environm & Nat Resources, Burlington, VT 05405 USA

关键词: Soil water;    Transpiration;    Carbon assimilation;    Water-use efficiency;    Biomass;   

DOI  :  10.1016/j.foreco.2019.117580

来源: Elsevier

【 摘 要 】

Scotch broom (Cytisus scoparius (L.) Link) is an invasive, N-fixing shrub in recently harvested Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) forests in the Pacific Northwest. The ability of Scotch broom to dominate a site and displace Douglas-fir in this region may be mediated by site quality and site resource supply. Individual seedlings of Scotch broom (n = 46) and Douglas-fir (n = 46) were planted in a controlled nursery setting and monitored over two years to test the effects of irrigation and fertilization treatments on the physiology and growth of these oft-conflicting species. Overall, Scotch broom remained largely unaffected by resource availability relative to Douglas-fir, which was more sensitive to water and nutrient availability. Scotch broom consistently showed greater assimilation and transpiration rates and plant water potentials than Douglas-fir under all treatments - indicating an elevated ability to acquire soil water resources. The conservative ecology of Douglas-fir resulted in greater water-use efficiency than Scotch broom throughout the experiment, however. Similarly, Douglas-fir crown and height growth started later in the growing season and ended earlier than that of Scotch broom, indicating a longer growing season for Scotch broom but also the importance of resource availability early in the growing season for Douglas-fir given its determinate growth. While Douglas-fir growth reflected the additive effects of increased resource availability, it did not surpass the growth of Scotch broom, which maintained steady growth and biomass accrual under all treatment conditions. The height of Douglas-fir growing under optimized conditions was approximately 40 cm less than that of Scotch broom regardless of treatment regime by the end of the two-year study. This demonstrates how critical early intervention is for land managers in order to control this invasive to avoid Scotch broom overtopping Douglas-fir seedlings during stand establishment.

【 授权许可】

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