Impacts of selective logging and agricultural clearing on forest structure, floristic composition and diversity, and timber tree regeneration in the Ituri Forest, Democratic Republic of Congo
Impacts of selective logging and agricultural clearing on forest structure, floristic composition and diversity, and timber tree regeneration in the Ituri Forest, Democratic Republic of Congo
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DOI：
10.1007/s10531-005-5397-6
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发表时间：
2006-04-01
影响因子：
3.4
通讯作者：
Thomas, Sean C.
中科院分区：
文献类型：
--
作者：
Makana, Jean-Remy;Thomas, Sean C.
农业前沿的成熟热带森林作为全球森林砍伐的前沿，受到全球保护关注。与其他热带森林地区一样，在刚果民主共和国的伊图里森林，与选择性采伐相关的道路建设导致人类自发殖民，导致成熟森林被砍伐用于农业目的。经过1-3年的耕种，农田休耕期可能超过20年，导致大面积的次生林区域受到选择性采伐和粗放式农业的影响。本研究对伊图里地区2个样地的次生林（5-10年及40年左右）、选择性采伐林和天然林的森林结构、树种组成和多样性以及木材的更新情况进行了评价。老次生林（40岁左右）的茎密度低于幼次生林和成熟林。不同林型间总体树木多样性差异不显著，但林分>= 10 cm dbh的幼龄次生林的树木多样性明显低于老次生林和成熟林分。次生林的物种组成与成熟林有所不同，成熟林的优势豆科植物在次生林中的代表性较差。然而，尽管先前采伐，高价值木材树木，如非洲红木（花木和红木）的再生在年轻次生林中至少是成熟森林的10倍。我们认为，如果管理和保护得当，次生林，即使是那些受到选择性采伐和小规模转移农业影响的次生林，也可能具有很高的保护潜力和经济价值。
Mature tropical forests at agricultural frontiers are of global conservation concern as the leading edge of global deforestation. In the Ituri Forest of DRC, as in other tropical forest areas, road creation associated with selective logging results in spontaneous human colonization, leading to the clearing of mature forest for agricultural purposes. Following 1-3 years of cultivation, farmlands are left fallow for periods that may exceed 20 years, resulting in extensive secondary forest areas impacted by both selective logging and swidden agriculture. In this study, we assessed forest structure, tree species composition and diversity and the regeneration of timber trees in secondary forest stands (5-10 and similar to 40 years old), selectively logged forest stands, and undisturbed forests at two sites in the Ituri region. Stem density was lower in old secondary forests (similar to 40 years old) than in either young secondary or mature forests. Overall tree diversity did not significantly differ between forest types, but the diversity of trees >= 10 cm dbh was substantially lower in young secondary forest stands than in old secondary or mature forests. The species composition of secondary forests differed from that of mature forests, with the dominant Caesalpinoid legume species of mature forests poorly represented in secondary forests. However, in spite of prior logging, the regeneration of high value timber trees such as African mahoganies (Khaya anthotheca and Entandrophragma spp.) was at least 10 times greater in young secondary forests than in mature forests. We argue that, if properly managed and protected, secondary forests, even those impacted by both selective logging and small-scale shifting agriculture, may have high potential conservation and economic value.