Conservation value of disturbed and secondary forests for ferns and lycophytes along an elevational gradient in Mexico
Conservation value of disturbed and secondary forests for ferns and lycophytes along an elevational gradient in Mexico
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DOI：
10.1111/avsc.12318
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发表时间：
2017-10-01
影响因子：
2.8
通讯作者：
Kessler, Michael
中科院分区：
文献类型：
--
作者：
Carvajal-Hernandez, Cesar I.;Kroemer, Thorsten;Kessler, Michael
问题蕨类植物群落的物种丰富度和组成如何随着海拔的变化而变化，以及在海拔带内，在受到不同影响的森林栖息地中？蕨类植物群落和小气候之间是否存在沿着海拔和干扰梯度的关系？哪些物种对栖息地干扰和小气候变化最敏感？位置从靠近墨西哥湾的海平面 81 公里处，位于墨西哥韦拉克鲁斯州中部海拔 3500 m 的 Cofre de Perote 东坡上。方法我们研究了 120 个研究地块中蕨类植物群落的丰富度和组成，这些研究地块位于 8 个海拔 20-3500 m 的三种森林类型中：天然林 (NF)、遭受木材采伐和放牧的受干扰森林 (DF) 以及 15-20 年前完全清除后的次生林 (SF) 重新生长。此外，我们在一年内测量了五个海拔高度的三种森林类型的小气候条件。结果蕨类植物丰富度在中海拔的潮湿山地森林中达到顶峰，而在梯度末端的干燥栖息地中则较低。潮湿的山地森林对干扰最敏感，与 NF 相比，DF 和 SF 的年平均气温升高约 1℃，相对空气湿度降低约 20%。与此同时，蕨类植物物种丰富度下降了 5-60%，物种组成也发生了显着变化。相比之下，低海拔的干旱落叶林和高海拔的针叶林在 NF 中已经具有低湿度和高光强度，并且受人类影响较小：它们的小气候条件和蕨类植物组合在 DF 和 SF 中没有显着变化。 山地森林依赖于对不受人类干扰的自然片段的保护。相比之下，只要保持总体森林结构，梯度末端的自然开放森林就可以进行一些开发，同时保留大部分蕨类植物区系。
QuestionsHow do species richness and composition of fern assemblages change with elevation and, within elevational belts, in differently impacted forest habitats? Is there a relationship between fern assemblages and microclimate, both along gradients of elevation and disturbance? Which species are most sensitive to habitat disturbance and microclimatic changes?LocationFrom sea level close to the Gulf of Mexico 81km away in a direct line on the eastern slopes of the Cofre de Perote at 3500m, central Veracruz, Mexico.MethodsWe studied the richness and composition of fern assemblages in 120 study plots at eight elevations from 20-3500m in three forest types: natural forest (NF), disturbed forest (DF) subjected to timber extraction and grazing, and secondary forest (SF) regrown after total clearance 15-20yr ago. In addition, we measured microclimatic conditions in the three forest types at five elevations over a year.ResultsFern richness peaked in humid montane forests at mid-elevations and was low in the drier habitats at the ends of the gradient. Humid montane forests were most sensitive to disturbance, showing increases in mean annual temperatures by about 1 degrees C and reduction in relative air humidity by about 20% in DF and SF compared to NF. This was together with a reduction in fern species richness of 5-60% and marked changes in species composition. In contrast, drought-deciduous forests at low elevations and coniferous forests at high elevations already had low humidity and high light intensity in NF and were less affected by human impact: their microclimatic conditions and fern assemblages did not change markedly in DF and SF.ConclusionsThe conservation of much of the humidity-dependent biota (ferns and presumably also groups such as bryophytes and amphibians) in humid montane forests depends on the protection of natural fragments without human disturbance. In contrast, the naturally open forests at the ends of the gradient can be subjected to some exploitation while conserving much of their fern flora as long as a general forest structure is maintained.