Early and repeated nutrient additions support far greater stemwood production in Norway spruce than traditional late-rotation fertilisation

作者：C. E. Svensson, Martin Karl‐Friedrich Bader, Benjamin Forsmark, Urban Nilsson, Tomas Lundmark, Annika Nordin, Johan Bergh · 发表于：Forest Ecology and Management · 年份：2023 · DOI：10.1016/j.foreco.2023.121425 · 被引用次数：7 · 研究领域：Forest ecology and management、Forest Ecology and Biodiversity Studies、Plant Water Relations and Carbon Dynamics

Silvicultural techniques aimed at promoting forest biomass production can help meet the growing demand for renewable materials and mitigate climate change. One-time nitrogen (N) addition late in the rotation is a well-established method to stimulate growth in coniferous forests in northern Europe, but the potential gains from earlier and repeated fertiliser application remain uncertain. Here, we tested the impact of repeated fertilisation in juvenile Norway spruce stands across 9 sites covering a wide range of growing conditions over a 700 km stretch from central to southern Sweden. We tested the fertilisation effects using two separate studies: i) an interval trial with a fertilisation frequency of one (F1), two (F2), or three years (F3) performed at plot-level across five sites (2002–2014), and ii) a practice-oriented trial with a two-year fertilisation interval (F2) applied at stand-level and replicated at four sites (2003–2013). The composition of the nutrient mix in each plot was optimised based on foliar nutrient analyses. In the interval trial, all three fertilisation schedules strongly increased periodic annual increment (PAI) (F1: 105 %, F2: 93 %, F3: 79 %) relative to the unfertilised control, resulting in more than a doubling of stem volume yield in the F1 and F2 treatments (110 % and 120 %, respectively) and a significantly smaller but still sizeable yield stimulation of 82 % in the F3 treatment. Nitrogen use efficiency (NUE, stemwood volume increase per unit mass...