In arid and semiarid forests and rangelands, native ranchers and farmers frequently use fire as a tool to improve soil fertility and vegetation composition, and to facilitate soil tilling. Investigating changes in ecosystem characteristics after these measures is of great importance for establishing management and recovery strategies. This study aimed to investigate spatial–temporal changes in the understory heterogeneity, diversity and composition after fires of different severities in a Brant's oak (Quercus brantii Lindl.) forest. Vegetation sampling was monitored in 14 patches including unburned sites (UBN), burned sites with low fire severity after 1, 5, and 10 years (LFSO, LFSF, and LFST, respectively), and burned sites with high fire severity after 1, 5, and 10 years (HFSO, HFSF, and HFST, respectively). Fire severity and time since fire significantly affected diversity indices with the lowest values of richness, evenness and diversity in high‐severity fires, while the highest values were observed in low‐severity fires. Time since fire did not significantly affect the understory evenness in both fire severities. However, species diversity and richness in low‐severity fires decreased with time since fire while the reverse was observed in high‐severity fires. The results of a detrended correspondence analysis indicated that the severity and time since fire significantly changed vegetation composition. The largest changes in vegetation composition compared to control sites were observed in HFSO, and then in HFSF and HFST. Both fire severity and time since fire caused changes in the heterogeneity of plant communities. We concluded that the use of low‐severity fires can be suitable for maintaining and increasing the heterogeneity of understory vegetation in semiarid forest ecosystems. However, low‐severity fires have also slightly, while not significantly, increased evenness and can therefore potentially reduce the ecosystem functions of dominant species in such semiarid regions. This could mitigate the positive effect of fire on vegetation heterogeneity and necessitate further investigations.

中文翻译：

---

在半干旱橡树（Quercus brantii Lindl。）森林中不同严重度的火灾后，林下异质性，多样性和组成的时空变化

在干旱和半干旱的森林和牧场中，当地牧场主和农民经常使用火作为改善土壤肥力和植被组成并促进土壤耕作的工具。在采取这些措施之后调查生态系统特征的变化对于建立管理和恢复策略非常重要。这项研究的目的是调查布兰特橡木桶（栎栎）火灾后不同严重程度下林下的异质性，多样性和组成的时空变化。林德（Lindl。）森林。在14个斑块中监测了植被采样，包括未烧毁地点（UBN），在1、5和10年后火灾严重程度较低的烧毁地点（分别为LFSO，LFSF和LFST）以及在1、5之后的严重火灾严重程度的烧毁地点，以及10年（分别为HFSO，HFSF和HFST）。火灾严重性和火灾以来的时间显着影响多样性指数，高烈度火灾中的丰富度，均匀性和多样性值最低，而低烈度火灾中的最高值。自火灾以来的时间并未严重影响两种火灾严重程度下的林下均匀度。但是，自烈火以来，低烈度火种的物种多样性和丰富度随时间下降，而高烈度火种则相反。去趋势对应分析的结果表明，火灾以来的严重程度和时间大大改变了植被组成。与对照地点相比，在HFSO，然后在HFSF和HFST中观察到植被组成的最大变化。火灾的严重程度和火灾以来的时间造成了植物群落异质性的变化。我们得出的结论是，使用低烈度火灾可能适合于维持和增加半干旱森林生态系统中林下植被的异质性。但是，低烈度火灾的均匀度也略有提高，但不显着，因此有可能降低这种半干旱地区优势物种的生态系统功能。这样可以减轻火灾对植被异质性的积极影响，因此有必要进行进一步研究。