Pérez-Molina Junior Pastor, Cordero Solórzano Roberto A
Laboratorio de Ecología Vegetal Funcional (LEVEF), Escuela de Ciencias Biológicas, Universidad Nacional de Costa Rica, Campus Omar Dengo, Heredia, Costa Rica.
Rev Biol Trop. 2012 Dec;60(4):1431-43.
In Costa Rica, the region of Rio Macho is a highly fragmented landscape with imminent risk of landslides. This area, which provides important environmental services, has been partially recovered to its original forest through intentional reforestation with exotic species or natural regeneration after abandonment. The aim of this study was to evaluate the bioindicator potential of oligochaete presence as well as some litter and soil characteristics. The ecosystem recovery of the two common restoration modes was measured within three different forest covers. For this, some substrate characteristics were analyzed and compared in a-50 years old secondary forest, a 13 years tacotal, and a 35 years cypress (Cupressus lusitanica) plantation. The three sites studied differed in density, biomass and average mass of oligochaetes, and in some litter (depth, nitrogen, phosphorus and C/N ratio of litter), and soil variables (soil water content (CA), pH, phosphorus, cation exchange capacity, and magnesium). The forest registered the lowest density of earthworms and soil pH, and the highest soil CA and phosphorus. CA was inversely related to the oligochaete density across sites. Besides, there were positive correlations between C/N and C/P ratios from the litter and soil pH, and inverse correlations of litter depth, litter N and P concentrations with soil P. Discriminant Analysis (AD) performed with all soil and litter variables, produced a sharp classification of the three forest cover types. AD suggests that site differences were mostly determined by soil CA and litter nitrogen concentration. Considering all the evaluated parameters, our results suggest in the first place, that oligochaetes are sensitive to changes in some soil and litter characteristics. Secondly, aside from the striking oligochaete differences between the old secondary forest and the other two sites, some soil and litter traits resulted good indicators of the present recovery of the three forest covers. In addition, comparing soil nutrients content (organic carbon, nitrogen, calcium, potassium and sulfur) among the three sites, our findings indicate that the cypress plantation had reached soil nutrient conditions similar to the old secondary forest, presumably by the accumulation of nutrients, as a result of low nutrient recirculation. In conclusion, ecosystem level studies throughout simple evaluation criteria (soils, oligochaetes and ground litter) can be used as rapid indicators of the state of some of the many and complex forest ecosystem compartments.
在哥斯达黎加，马乔河地区是一个高度破碎化的景观区域，面临着山体滑坡的紧迫风险。该地区提供重要的环境服务，通过引入外来物种进行人工造林或在弃耕后自然恢复，部分区域已恢复到原始森林状态。本研究的目的是评估寡毛纲动物的生物指示潜力以及一些凋落物和土壤特征。在三种不同的森林覆盖类型中，对两种常见恢复模式的生态系统恢复情况进行了测量。为此，在一片50年树龄的次生林、一片13年树龄的塔科塔尔林和一片35年树龄的柏树（Cupressus lusitanica）人工林中，对一些基质特征进行了分析和比较。所研究的三个地点在寡毛纲动物的密度、生物量和平均质量，以及一些凋落物（凋落物深度、氮、磷和C/N比）和土壤变量（土壤含水量（CA）、pH值、磷、阳离子交换容量和镁）方面存在差异。森林中蚯蚓密度和土壤pH值最低，土壤CA和磷含量最高。 across sites，CA与寡毛纲动物密度呈负相关。此外，凋落物和土壤pH值的C/N和C/P比之间存在正相关，凋落物深度、凋落物N和P浓度与土壤P呈负相关。对所有土壤和凋落物变量进行判别分析（AD），对三种森林覆盖类型进行了清晰的分类。AD表明，地点差异主要由土壤CA和凋落物氮浓度决定。综合所有评估参数，我们的结果首先表明，寡毛纲动物对某些土壤和凋落物特征的变化敏感。其次，除了老龄次生林与其他两个地点之间寡毛纲动物存在显著差异外，一些土壤和凋落物特征是三种森林覆盖类型当前恢复情况的良好指标。此外，比较三个地点的土壤养分含量（有机碳、氮、钙、钾和硫），我们的研究结果表明，柏树人工林的土壤养分状况已达到与老龄次生林相似的水平，这可能是由于养分循环率低导致养分积累的结果。总之，通过简单的评估标准（土壤、寡毛纲动物和地表凋落物）进行的生态系统水平研究，可以作为许多复杂森林生态系统组成部分中某些部分状态的快速指标。
