OREGON STATE UNIVERSITY

Capacity of biochar application and nitrogen fertilization to mitigate grass competition upon tree seedlings during stand regeneration

TitleCapacity of biochar application and nitrogen fertilization to mitigate grass competition upon tree seedlings during stand regeneration
Publication TypeJournal Article
Year of Publication2016
AuthorsKrapfl KJ, Hatten JA, Roberts SD, Baldwin BS, Rousseau RJ, Shankle MW
JournalForest Ecology and Management
Volume376
Pagination298 - 309
Date Published2016///
Abstract

Background and aims: This experiment examined early competition dynamics of a tree-grass intercropping system. We hypothesized that (1) the effects of competition would outweigh those of facilitation in this system and (2) soil amendment-induced fertility would alter competitive relationships between these species. Methods: We intercropped loblolly pine and switchgrass seedlings at three rates of density-induced interspecific competition (high, low, and pine only) and amended soils with biochar (0, 5, and 20 Mg ha1) and nitrogen fertilizer (0 and 56 kg ha1 N). We measured soil properties, foliar N concentrations, and plant productivity over two years. Results: Soil temperatures decreased and total soil N increased in intercropping treatments relative to the pine only control treatment. Competition reduced soil moisture and inorganic N concentrations as well as tree productivity and switchgrass yields. Biochar amendments increased total soil C, C:N ratios, and soil moisture. Fertilization acidified soil pH and decreased total soil C and N pools. Switchgrass yields were increased and soil moisture was decreased with N fertilization. Conclusions: The net effects of competition outweighed those of facilitation within this system. Competitive relationships amongst these species were altered by soil amendment-induced fertility. Favorable switchgrass responses to soil inorganic N suggests its competitive ability is increased on nitrogen-rich or fertilized sites.

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0378112716303279