Coordenação de Pesquisas em Ecologia, Instituto Nacional de Pesquisas da Amazônia, Manaus, AM, Brazil.
Conserv Biol. 2010 Feb;24(1):278-86. doi: 10.1111/j.1523-1739.2009.01299.x. Epub 2009 Jul 21.
In Amazonia reduced-impact logging, which is meant to reduce environmental disturbance by controlling stem-fall directions and minimizing construction of access roads, has been applied to large areas containing thousands of streams. We investigated the effects of reduced-impact logging on environmental variables and the composition of fish in forest streams in a commercial logging concession in central Amazonia, Amazonas State, Brazil. To evaluate short-term effects, we sampled 11 streams before and after logging in one harvest area. We evaluated medium-term effects by comparing streams in 11 harvest areas logged 1-8 years before the study with control streams in adjacent areas. Each sampling unit was a 50-m stream section. The tetras Pyrrhulina brevis and Hemigrammus cf. pretoensis had higher abundances in plots logged > or =3 years before compared with plots logged <3 years before. The South American darter (Microcharacidium eleotrioides) was less abundant in logged plots than in control plots. In the short term, the overall fish composition did not differ two months before and immediately after reduced-impact logging. Temperature and pH varied before and after logging, but those differences were compatible with normal seasonal variation. In the medium term, temperature and cover of logs were lower in logged plots. Differences in ordination scores on the basis of relative fish abundance between streams in control and logged areas changed with time since logging, mainly because some common species increased in abundance after logging. There was no evidence of species loss from the logging concession, but differences in log cover and ordination scores derived from relative abundance of fish species persisted even after 8 years. For Amazonian streams, reduced-impact logging appears to be a viable alternative to clear-cut practices, which severely affect aquatic communities. Nevertheless, detailed studies are necessary to evaluated subtle long-term effects.
在亚马逊地区，采用了减少影响的伐木方式（通过控制树干倒下的方向和尽量减少道路建设来减少环境干扰），已经应用于包含数千条溪流的大面积地区。我们研究了减少影响的伐木方式对环境变量和鱼类组成的影响，这些溪流位于巴西亚马孙州亚马逊地区的一个商业伐木特许经营区的森林中。为了评估短期影响，我们在一个采伐区中，在伐木前后对 11 条溪流进行了采样。为了评估中期影响，我们比较了在研究前 1-8 年内被采伐的 11 个采伐区的溪流与相邻区域的对照溪流。每个采样单元是 50 米的溪流段。短盖巨脂鲤（Pyrrhulina brevis）和黑带副唇脂鲤（Hemigrammus cf. pretoensis）的丰度在被采伐 >或=3 年前的样方中比在被采伐 <3 年前的样方中更高。南美的刺盖鱼（Microcharacidium eleotrioides）在被采伐的样方中比在对照样方中的丰度更低。在短期内，减少影响的伐木后两个月与立即进行时，鱼类总体组成没有差异。温度和 pH 值在伐木前后有所变化，但这些差异与正常的季节性变化相兼容。在中期，温度和原木覆盖度在被采伐的样方中较低。在控制区和采伐区的溪流中，基于鱼类相对丰度的排序得分的差异随着时间的推移而变化，主要是因为一些常见的物种在伐木后丰度增加。从伐木特许经营区没有证据表明物种损失，但原木覆盖度和排序得分的差异仍然存在，即使在 8 年后也是如此。对于亚马逊地区的溪流，减少影响的伐木方式似乎是一种可行的替代方案，因为传统的皆伐方式严重影响水生群落。然而，需要进行详细的研究来评估微妙的长期影响。
