Seed production and recruitment in primary and harvested Nothofagus pumilio forests: Influence of regional climate and years alter cuttings

TORRES, AD; CELLINI, JM; LENCINAS, MV; BARRERA, M; SOLER, R; DÍAZ-DELGADO, R; MARTÍNEZ PASTUR, G

Forest Systems

Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria-INIA

Año: 2015 vol. 24 p. 1 - 11

Aim of study:Harvesting proposals (e.g. variable retention) for Nothofagus pumilio forestsare based on canopy opening, to increase recruitment and enhance seedlinggrowth, by modifying light and soil moisture. Seed production and seedlingrecruitment will define the success of harvesting, where remnant foreststructure are the main influence factors, as well as biotic and abiotic factors.The objective was to analyse seed production, seedling recruitment andrecruitment efficiency in primary and harvested forests throughvariable retention along the first 10 years after harvesting, as well as theinfluence of regional climate.Area of study: Thestudy were conducted in a pure Nothofagus pumilio forest located in centralTierra del Fuego (54°18? S, 67°49? W), where harvested stands with variableretention and unmanaged forests were sampled in long-term permanent plots.Material and methods:Data of forest regeneration plots were used (n = 72) (2007 a 2014), and foreststructure and seed production (2006 a 2013) were also measured. Regional climate wascharacterised for these years from satellite images (Sea Surface Temperature)and climate re-analysis models (rainfall and temperature of land surface).Main results:Harvesting modified forest structure; however, aggregated retention maintainedsome characteristics of the primary unmanaged forests. These changes influencedseed production and recruitment. Seed production and recruitment were related tocrown cover and the amount of seed production; however, recruitment efficiencywas not affected by harvesting. The studied variables significantly changedalong the years after harvesting. Seed production and recruitment were alsorelated to regional climate factors, where it was possible to explain theirvariations through temperature (e.g. summer temperature) and rainfall (e.g. winterrainfall) for the different retention types in harvested forests and theprimary forests.Research highlights:Variable retention harvesting generated different micro-conditions thatinfluence seed production and recruitment. These variables were related tocanopy cover. However, recruitment efficiency was not affected by harvesting.Seed production and recruitment (primary forests and harvested stands) wererelated to regional climate factors and their variations can be explained fromvariables related to temperature and rainfall.