Lizards along an agricultural land abandonment gradient in Pindos Mountains, Greece

Agricultural land abandonment is recognized as one of the main environmental drivers in Southern Europe, affecting ecological communities. Lizards, as ectothermic species with low dispersal capacity, are particularly prone to the threats associated with land use changes. We investigated the effect of land abandonment on lizards in a remote mountainous area in Greece, using line transect sampling, in 20 randomly selected sites [1 km × 1 km], along a four grade abandonment gradient in terms of forest encroachment. We recorded four species: Algyroides nigropunctatus, Lacerta viridis/ trilineata, Podarcis tauricus and Podarcis muralis, the latter being the most abundant. Our results did not provide evidence for a significant effect of forest encroachment or grazing on lizard diversity, given the dominance of P. muralis, the availability of all microhabitat types along the gradient and the low grazing intensity in the study area. Environmental parameters at the macrohabitat scale did not prove determinant for habitat variance, but microhabitat analysis showed a clear preference of P. muralis to bare ground. Despite the non-significant effects of land abandonment on lizard diversity, the dominance of P. muralis tends to indicate a lizard community shift towards species inhabiting forested habitats. The preservation of open microhabitats, such as bare land, is considered of great importance for promoting high levels of lizard diversity, as their loss would affect even species currently widespread in forested ecosystems. Low intensity grazing, as well as the enhancement of wild ungulate populations in abandoned areas, can contribute to halting forest encroachment and maintaining the required habitat heterogeneity.

农田荒废被视为南欧地区的主要环境驱动因素之一，对生态群落产生显著影响。蜥蜴作为散布能力较低、体温调节为变温的物种，特别容易受到土地利用变化带来的威胁。本研究在希腊一处偏远山区，通过线状样带法，在20个随机选取的[1公里×1公里]样地内，沿着以森林入侵为标准的四个等级的荒废梯度进行了调查。我们记录了四种物种：Algyroides nigropunctatus、Lacerta viridis/trilineata、Podarcis tauricus以及Podarcis muralis，其中Podarcis muralis数量最为丰富。鉴于Podarcis muralis的占主导地位、梯度上所有微生境类型的可用性以及研究区域低强度的放牧，我们的研究结果并未提供森林入侵或放牧对蜥蜴多样性产生显著影响的证据。在宏观生境尺度上，环境参数并未证明对生境变异性具有决定性作用，但微生境分析表明Podarcis muralis对裸露地面的偏好显著。尽管农田荒废对蜥蜴多样性的影响并不显著，但Podarcis muralis的占主导地位倾向于表明蜥蜴群落向栖息于森林生境的物种转变。保护开放的微生境，如裸露土地，对于促进蜥蜴多样性达到高水平具有重要意义，因为其丧失将影响甚至目前广泛分布于森林生态系统的物种。低强度放牧以及增强废弃区域野生动物群落的数量，可以有助于遏制森林入侵并维持所需的生境异质性。