Inclusion criteria influence species richness, diversity and forest structure with implications to deforestation permits in Rio de Janeiro State, Brazil

ABSTRACT Deforestation requests to government decision-makers aim for the legal permission to remove secondary forests for economic reasons. In the State of Rio de Janeiro, Resolução Conama nº 06/1994 drives the analysis of successional stages of such forests. It does not define which inclusion criterion (diameter at breast height) should be used in forest inventories. We used Floresta da Cicuta as a case study to evaluate the influence of different inclusion criteria on species richness, diversity and structure parameters having Resolução Conama nº 06/1994 as background. Using Hill numbers, we found that the DBH ≥ 2.5 cm highlighted species richness. Species richness is improperly addressed in Resolução Conama nº 06/1994. The use of DBH ≥ 2.5 cm detected 30 individuals of threatened species, while DBH ≥ 10 cm detected only nine. Basal area was the most accurate parameter to identify the successional stage. Mean DBH and mean height misidentified successional stage. We strongly advise environmental authorities to demand the use of DBH ≥ 2.5 cm in forest inventories for deforestation requests. We strongly encourage the review of Resolução Conama nº 06/1994 by environmental authorities in order to reduce the risk of mistaken classification of successional stage of secondary forests.摘要：向政府决策者提交的伐林申请，旨在获取因经济用途采伐次生林的合法许可。在里约热内卢州，《Conama第06/1994号决议》（Resolução Conama nº 06/1994）是此类森林演替阶段分析的核心依据，但该决议未明确森林调查中应采用何种纳入标准（即胸高直径（DBH, diameter at breast height）标准）。本研究以毒芹林（Floresta da Cicuta）为案例研究对象，以《Conama第06/1994号决议》为研究背景，评估不同纳入标准对物种丰富度、多样性及群落结构参数的影响。本研究采用希尔数（Hill numbers）开展分析，结果显示，采用胸高直径≥2.5 cm的纳入标准可更精准地体现物种丰富度。《Conama第06/1994号决议》中对物种丰富度的界定并不恰当。当采用胸高直径≥2.5 cm的标准时，共检测到30株受威胁物种个体，而采用胸高直径≥10 cm的标准时仅检测到9株。基面积是识别森林演替阶段最为精准的参数，平均胸高直径与平均树高则会导致演替阶段的误判。本研究强烈建议环境主管部门在伐林申请的森林调查中，要求采用胸高直径≥2.5 cm的纳入标准，并敦促环境主管部门对《Conama第06/1994号决议》进行修订，以降低次生林演替阶段分类错误的风险。