Data from: Bryophyte abundance, diversity and composition after retention harvest in boreal mixedwood forest

1. Variable-retention harvest is widely recognised as an alternative to more intensive methods such as clear-cutting. However, present information is inadequate to judge impact of variable-retention on biodiversity of indigenous forest organisms intolerant of canopy removal, such as forest-inhabiting bryophytes. 2. We examined how bryophyte species cover, richness, diversity and composition change with time in response to a broad range of dispersed retention harvest treatments (2% (clear-cut), 10%, 20%, 50%, 75% retention of original basal area) contrasted with uncut controls (100% retention)) in broadleaf deciduous, mixedwood and conifer-dominated boreal forests in NW Alberta, Canada. Bryophytes were studied in 432 permanent sample plots within 72 compartments before harvest and at three, six and eleven years after harvest. 3. Clear-cut and lower (10% and 20%) retention levels resulted in lower cover and richness of bryophytes than in unharvested control compartments in mixed and conifer-dominated forests, but less so in deciduous-dominated forests, which generally supported low cover and richness. Species composition in each forest type varied along the gradient of harvesting intensity; clear-cuts and lower levels of retention supported similar composition, as did control plots and those representing higher retention levels. Over time the retention harvest treatments became more similar to uncut controls. 4. Synthesis and applications. Increased retention moderated the negative impacts of harvesting on bryophyte assemblages across all forest types, and our results suggest that even 10% retention will facilitate faster post-harvest recovery of bryophytes.02-Aug-2017

1. 可变保留采伐（variable-retention harvest）已被广泛认可为皆伐等高强度采伐方式的替代方案。然而，当前相关信息尚不足以评估可变保留采伐对不耐受林冠移除的本土森林生物（如栖息于森林的苔藓植物（bryophytes））生物多样性的影响。2. 本研究针对加拿大阿尔伯塔省西北部的落叶阔叶林、针阔混交林及针叶林主导的寒温带森林，设置了一系列分散式保留采伐处理（分别保留原始胸高断面积的2%（即皆伐）、10%、20%、50%、75%），并以未采伐的对照样地（保留100%胸高断面积）作为参照，探究苔藓植物的盖度、物种丰富度、多样性及群落组成随时间的变化规律。研究在采伐前及采伐后3年、6年、11年，对72个林班内的432个永久样地中的苔藓植物开展调查。3. 在针阔混交林和针叶林主导的森林中，皆伐及低保留水平（10%、20%）样地的苔藓植物盖度与物种丰富度均低于未采伐对照样地；而在落叶阔叶主导的森林中，该差异相对较小——这类森林本身的苔藓植物盖度与物种丰富度普遍较低。各林型的苔藓植物群落组成随采伐强度梯度呈现规律性变化：皆伐与低保留水平样地的群落组成相似，未采伐对照与高保留水平样地的群落组成亦相近。随着时间推移，各保留采伐处理样地的苔藓群落组成逐渐趋近于未采伐对照样地。4. 综合与应用。本研究结果表明，提高保留率可缓解采伐对所有林型下苔藓植物群落的负面影响，且即便仅保留10%的胸高断面积，也可促进苔藓植物在采伐后更快恢复。2017年8月2日