Zagros forests in western Iran have been impacted by severe fuelwood removal, traditional agricultural systems, non-timber products removal, and livestock grazing. These conditions have led to the forest area diminishing from 10 to 6 million hectares over the last six decades. This study was conducted to understand the consequences of livestock exclusion on understory plant diversity, forest tree regeneration, and soil physicochemical properties in semiarid forests. We selected four neighbouring areas, including those subject to livestock exclusion and to grazing, in the Zagros oak forests of Iran. Ten randomized sampling plots (400 m2) were established, and all plant species were recorded in each area. A soil physicochemical analysis indicated a significant improvement in soil nitrogen, phosphorous, potassium, and organic matter in the livestock exclusion area compared to the grazing area. The Shannon–Wiener diversity and species richness was also significantly higher in the livestock exclusion areas compared to the grazed. Grazing tolerant species like Poa bulbosa were abundant in grazing areas, while palatable and nitrogen-fixing species disappeared. The tree regeneration rate was significantly higher in the exclusion areas compared to the grazing areas, and its values were 0.079 and 0.006 per square metre in the exclusion and grazing areas, respectively. The results of the present study provided evidence that exclusion had a significant effect on improving soil chemical properties, understory plant diversity index, and sapling regeneration. However, the regeneration rates were still low, and therefore, livestock exclusion alone may not be enough to promote forest restoration. Therefore, to better understand plant diversity and tree regeneration in the Zagros forests, livestock exclusion and other factors such as soil seed bank and socio-economic status of people should be considered.

中文翻译：

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牲畜排斥对伊朗半干旱森林树木再生、林下植物多样性和土壤特性的有益影响

伊朗西部的扎格罗斯森林受到严重的薪材砍伐、传统农业系统、非木材产品砍伐和牲畜放牧的影响。在过去的 60 年里，这些条件导致森林面积从 10 公顷减少到 600 万公顷。本研究旨在了解牲畜排斥对半干旱森林林下植物多样性、林木再生和土壤理化特性的影响。我们在伊朗的扎格罗斯橡树林中选择了四个邻近地区，包括那些受到牲畜排斥和放牧的地区。建立了 10 个随机抽样小区（400 m2），记录了每个区域的所有植物种类。土壤理化分析表明土壤氮、磷、钾、与放牧区相比，牲畜禁区中的有机物和有机物。与放牧区相比，牲畜禁区的香农-维纳多样性和物种丰富度也显着提高。耐放牧的物种，如早熟禾在放牧区丰富，而可口和固氮物种消失了。与放牧区相比，禁区的树木更新率显着高于放牧区，禁区和放牧区的值分别为每平方米0.079和0.006。本研究结果提供了证据，证明排斥对改善土壤化学性质、林下植物多样性指数和树苗再生具有显着影响。然而，再生率仍然很低，因此仅靠排除牲畜可能不足以促进森林恢复。因此，为了更好地了解扎格罗斯森林中的植物多样性和树木再生，应考虑牲畜排斥和其他因素，如土壤种子库和人们的社会经济地位。