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）被广泛认为是皆伐（clear-cutting）等高强度采伐方式的替代方案。然而，当前现有信息尚不足以评估可变保留采伐对不耐受冠层移除的本土森林生物（如栖息于森林的苔藓植物（bryophytes））的生物多样性所产生的影响。2. 本研究针对加拿大阿尔伯塔省西北部的落叶阔叶林、混交林以及针叶林占优的北方林（boreal forests），设置了一系列分散式保留采伐处理，分别保留原始断面积（original basal area）的2%（即皆伐）、10%、20%、50%、75%，并以未采伐对照样地（uncut controls，保留100%原始断面积）作为参照，探究苔藓植物的物种盖度、丰富度、多样性及组成随时间的变化规律。研究于采伐前以及采伐后3年、6年和11年，在72个采伐单元（compartments）内的432个永久样地（permanent sample plots）中对苔藓植物开展调查。3. 在混交林与针叶林占优的林分中，皆伐与低保留水平（10%、20%）样地的苔藓植物盖度与丰富度均低于未采伐对照单元；而在以落叶阔叶占优的林分中，这一差异相对较小——此类林分本身的苔藓植物盖度与丰富度普遍偏低。各林分类型的苔藓物种组成随采伐强度梯度发生变化：皆伐与低保留水平样地的物种组成相似，未采伐对照与高保留水平样地亦同理。随着时间推移，保留采伐处理样地的苔藓群落愈发接近未采伐对照样地。4. 综合与应用（Synthesis and applications）。在所有林分类型中，提高保留水平均可缓解采伐对苔藓群落（bryophyte assemblages）造成的负面影响；研究结果表明，即便仅保留10%的原始断面积，也可促进苔藓植物在采伐后更快完成群落恢复。2017年8月2日