Vegetation structure, species diversity, and composition have been monitored at a fire-treatment and a fire-free control unit of a dry oak barrens and woodland complex in southern Illinois, USA, over a 29-year period and five burns. The restoration hypothesis is that fire management would result in different trends for vegetation parameters of conservation interest between fire treatment and control units, that before–after differences would be greater with fire management, and that early trends provide a reliable predictor for later outcomes. This study examines effectiveness of management in achieving restoration goals and uses response to the first two burns and monitoring results over the first seven years as an estimation period to test whether early trends with fire treatment are a reliable predictor for outcomes following three additional burns over the following 22 years. Trends differed between fire-treatment and control units for all parameters measured, and before–after differences were greater at the fire treatment unit. However, trends at the fire-treatment unit during the estimation period were a poor predictor of later outcomes. Tree density and basal area declined more than expected while ground-layer species density, richness, diversity, and percent cover did not keep pace with expectations of increase. Trends at the control unit were more predictable; however, tree basal area declined more than expected, possibly due to an outbreak of rapid white oak mortality disease, and decline of ground-layer species density was less than predicted from the early estimation period. Results suggested that fire alone can be effective at restoring woodland and barrens natural areas and that a fire return interval of about every four years would be optimal for maintaining composition and diversity in this specific oak barrens habitat. However, burns followed immediately by severe drought possibly can have negative interactions, resulting in declines of ground-layer species diversity.

中文翻译：

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橡树贫瘠的火处理的早期趋势是否可以预测较晚的结果？三十年来植被监测的见解

在美国伊利诺伊州南部的一个干燥的橡树荒地和林地综合体的火灾处理和无火控制单元中，对植被的结构，物种多样性和组成进行了监测，历时29年，共烧了5次。恢复假说是，火灾管理将导致火灾处理与控制单位之间具有保护意义的植被参数的趋势不同，火灾管理前后的差异将更大，并且早期趋势可为以后的结果提供可靠的预测指标。这项研究检查了管理在实现恢复目标方面的有效性，并使用了对前两次烧伤的反应并在最初的七年中监测了结果，以此作为估计期，以测试火灾的早期趋势是否可以可靠地预测火灾发生后的三个烧伤结果。接下来的22年。消防部门和控制部门在所有测量参数上的趋势都不同，消防部门前后的差异更大。但是，在估计期间，消防部门的趋势无法预测以后的结果。树木密度和基础面积的下降幅度超过了预期，而地上树种的密度，丰富度，多样性和覆盖率却没有与增长预期保持同步。控制单元的趋势更可预测；然而，树木基部面积的下降幅度超过了预期，这可能是由于白橡树快速死亡病的爆发所致，并且地表物种密度的下降幅度小于早期估计时期的预测值。结果表明，单独的火灾可以有效地恢复林地和贫瘠的自然地区，并且大约每四年的返火间隔对于维持这种特定的橡树贫瘠的栖息地的组成和多样性是最佳的。但是，紧接着严重干旱的烧伤可能会产生不利的相互作用，从而导致地层物种多样性下降。结果表明，单独的火灾可以有效地恢复林地和贫瘠的自然地区，并且大约每四年的返火间隔对于维持这种特定的橡树贫瘠的栖息地的组成和多样性是最佳的。但是，紧接着严重干旱的烧伤可能会产生不利的相互作用，从而导致地层物种多样性下降。结果表明，单独的火灾可以有效地恢复林地和贫瘠的自然地区，并且大约每四年的返火间隔对于维持这种特定的橡树贫瘠的栖息地的组成和多样性是最佳的。但是，紧接着严重干旱的烧伤可能会产生不利的相互作用，从而导致地层物种多样性下降。