Data from: Savannas after afforestation: assessment of herbaceous community responses to wildfire versus native tree planting

Afforestation and fire exclusion are pervasive threats to tropical savannas. In Brazil, laws limiting prescribed burning hinder the study of fire in the restoration of Cerrado plant communities. We took advantage of a 2017 wildfire to evaluate the potential for tree cutting and fire to promote the passive restoration of savanna herbaceous plant communities after destruction by exotic tree plantations. We sampled a burned pine plantation (Burned Plantation); a former plantation that was harvested and burned (Harvested & Burned); an unburned former plantation that was harvested, planted with native trees, and treated with herbicide to control invasive grasses (Native Tree Planting); and two old-growth savannas which served as reference communities. Our results confirm that herbaceous plant communities on post-afforestation sites are very different from old-growth savannas. Among post-afforestation sites, Harvested & Burned herbaceous communities were modestly more similar in composition to old-growth savannas, had slightly higher richness of savanna plants (3.8 species per 50-m2), and supported the greatest cover of native herbaceous plants (56%). These positive trends in herbaceous community recovery would be missed in assessments of tree cover: whereas canopy cover in the Harvested & Burned site was 6% (less than typical of savannas of the Cerrado), the Burned Plantation and Native Tree Planting, supported 34% and 19% cover, respectively. By focusing on savanna herbaceous plants, these results highlight that tree cutting and fire, not simply tree planting and fire exclusion, should receive greater attention in efforts to restore savannas of the Cerrado.

人工造林与禁火是热带稀树草原面临的普遍威胁。在巴西，限制计划性火烧（prescribed burning）的法律法规阻碍了针对塞拉多（Cerrado）植物群落修复中火烧作用的相关研究。本研究借助2017年的一场野火，评估了在外来人工林破坏后的稀树草原草本植物群落被动修复中，林木砍伐与火烧的应用潜力。我们共设置四类采样样地：遭火烧的人工松林（Burned Plantation）、经采伐与火烧的原人工林（Harvested & Burned）、未遭火烧且经采伐、种植本土树木并施用除草剂防控入侵草本的原人工林（Native Tree Planting），以及两块作为参照群落的成熟稀树草原。研究结果证实，人工造林后迹地的草本植物群落与成熟稀树草原存在显著差异。在人工造林后迹地中，经采伐与火烧样地的草本群落组成与成熟稀树草原的相似度相对更高，其稀树草原植物的物种丰富度略高（每50平方米3.8种），且本土草本植物盖度最高（56%）。若仅通过林木冠层盖度开展评估，将错失草本群落恢复的这些积极趋势：经采伐与火烧样地的冠层盖度仅为6%（低于塞拉多稀树草原的典型水平），而火烧迹地人工松林与本土树木种植样地的冠层盖度分别为34%与19%。本研究聚焦稀树草原草本植物，结果表明，在塞拉多稀树草原修复工作中，应更加重视林木砍伐与火烧措施，而非单纯依赖植树造林与禁火手段。