Setor de Ecologia e Conservação, Departamento de Biologia, Universidade Federal de Lavras, Lavras, MG, Brazil.
Department of Biology and the Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, St. Louis, MO, United States of America.
PLoS One. 2018 Aug 22;13(8):e0201873. doi: 10.1371/journal.pone.0201873. eCollection 2018.
The Brazilian Cerrado is one of the most endangered biomes in the world. We evaluated the sustainability of leaf harvest in one of the most important Cerrado tree species, Stryphnodendron adstringens. The bark of this tree is used as a source of medicinal tannin. Harvesting bark, however, often kills the tree. In a manipulative field experiment, we tested the hypothesis that harvesting leaves, which might serve as an alternative source of tannin, would be less detrimental for tree survival, growth, reproduction, and defense than harvesting bark. In a two-way crossed experimental design, we either clipped 100% of a plant's leaves or applied NPK fertilizer to the soil. Our predictions of the experimental outcomes were based on plant resource and defense theory. Growth was determined by total leaf dry mass production, reproduction by inflorescence and fruit production traits, and defense by total phenolics, hydrolyzable tannins, and condensed tannins. Fertilization had a marginally positive effect on total leaf dry mass. Defoliation had no effect on subsequent leaf production, and most importantly, no plants died as a result of defoliation. We found high tannin amounts in leaves of S. adstringens produced both prior to and subsequent to clipping, further suggesting that leaves could serve as a sustainable alternative source of tannin. After clipping, plants invested more in tannin production and less in reproduction. Our results suggest that leaf harvest may be more sustainable than harvesting of bark in S. adstringens. We suggest the need for further investigation of the medicinal properties of leaf tannins to formulate a viable sustainable management plan for the exploitation of this plant species.
巴西塞拉多是世界上最濒危的生物群落之一。我们评估了在塞拉多最重要的树种之一，斯泰弗诺登德龙·阿丁斯特伦斯（Stryphnodendron adstringens）中进行叶片收获的可持续性。这种树的树皮被用作药用单宁的来源。然而，收获树皮常常会杀死树木。在一项操纵性的田间实验中，我们检验了这样一个假设，即收获树叶（可能是单宁的替代来源）对树木的存活、生长、繁殖和防御的危害要小于收获树皮。在双向交叉实验设计中，我们要么剪掉植物叶片的 100%，要么向土壤中施加 NPK 肥料。我们对实验结果的预测是基于植物资源和防御理论。生长通过总叶干质量产量来确定，繁殖通过花序和果实生产性状来确定，防御通过总酚类、可水解单宁和缩合单宁来确定。施肥对总叶干质量有轻微的积极影响。去叶对随后的叶片生产没有影响，最重要的是，没有植物因去叶而死亡。我们发现斯泰弗诺登德龙·阿丁斯特伦斯的叶片中含有大量的单宁，无论是在修剪前还是修剪后都有大量的单宁，这进一步表明叶片可以作为一种可持续的单宁替代来源。修剪后，植物在单宁生产上的投入增加，在繁殖上的投入减少。我们的研究结果表明，在斯泰弗诺登德龙·阿丁斯特伦斯中，叶片收获可能比树皮收获更具可持续性。我们建议需要进一步研究叶片单宁的药用特性，以制定一种可行的可持续管理计划，以开发这种植物物种。
