Karatassiou Maria, Parissi Zoi M, Panajiotidis Sampson, Stergiou Afroditi
Laboratory of Rangeland Ecology, School of Forestry and Natural Environment, Aristotle University of Thessaloniki, P.O. Box 286, 54124 Thessaloniki, Greece.
Laboratory of Range Science, School of Forestry and Natural Environment, Aristotle University of Thessaloniki, P.O. Box 236, 54124 Thessaloniki, Greece.
Plants (Basel). 2022 Apr 4;11(7):982. doi: 10.3390/plants11070982.
The rangelands of Crete island (Greece) are typical Mediterranean habitats under high risk of degradation due to long-term grazing and harsh climatic conditions. We explored the effect of abiotic (climatic conditions, altitude) and biotic factors (long-term grazing by small ruminants) on the floristic composition and diversity of selected lowland (Pyrathi, Faistos) and highland (Vroulidia, Nida) rangelands. In each rangeland, the ground cover was measured, and the floristic composition was calculated in terms of five functional groups: grasses, legumes, forbs, phrygana, and shrubs. The aridity index, species turnover, species richness, Shannon entropy, and Gini-Simpson index (with the latter two converted to the effective number of species) were calculated. Our results reveal that highlands are characterized by the highest aridity index (wetter conditions). Lowland rangelands, compared to highland, exhibited a higher percentage contribution of grasses, legumes, and forbs, while species turnover decreased along the altitudinal gradient. The Shannon entropy index was correlated (a) positively with Gini-Simpson and mean annual temperature and (b) negatively with mean annual precipitation, aridity index, and altitude. Moreover, the Gini-Simpson index correlated positively with mean annual temperature and negatively with altitude. Our results could help to understand the effects of grazing on rangeland dynamics and sustainability in semi-arid regions in the context of climatic change.
希腊克里特岛的牧场是典型的地中海栖息地，由于长期放牧和恶劣的气候条件，面临着很高的退化风险。我们探究了非生物因素（气候条件、海拔）和生物因素（小型反刍动物的长期放牧）对选定的低地（皮拉蒂、法伊斯托斯）和高地（弗鲁利迪亚、尼达）牧场植物区系组成和多样性的影响。在每个牧场中，测量了地被植物覆盖度，并根据五个功能组计算了植物区系组成：禾本科、豆科、杂草类、地中海常绿矮灌丛和灌木。计算了干旱指数、物种周转率、物种丰富度、香农熵和基尼-辛普森指数（后两者转换为有效物种数）。我们的结果表明，高地的干旱指数最高（气候较湿润）。与高地相比，低地牧场的禾本科、豆科和杂草类的贡献百分比更高，而物种周转率沿海拔梯度降低。香农熵指数与（a）基尼-辛普森指数和年平均温度呈正相关，与（b）年平均降水量、干旱指数和海拔呈负相关。此外，基尼-辛普森指数与年平均温度呈正相关，与海拔呈负相关。我们的结果有助于理解在气候变化背景下，放牧对半干旱地区牧场动态和可持续性的影响。
