Natural temperate grasslands are endangered throughout their range, largely because of their almost complete conversion to agriculture, and by changes in fire and grazing regimes. Woody encroachment by shrubs is a global threat to the structure, function and composition of grasslands. We wished to determine the characteristics of fire regimes that prevent or reverse woody plant encroachment, maintain native species richness and minimise exotic plant invasion in temperate grassland at the Surrey Hills Tasmania, where a fire management plan with variable prescriptions had been implemented for two decades. We collected floristic, fire regime and environmental data from 105 quadrats (1 × 10 m) in 2016/2017, and compared the data from 2016/2017 to that from a 1994 survey using the same methods. A high frequency and cover of native shrubs characterised areas unburned for at least 20 years before 2017, but not those unburned in the 20 years before 1994. Shrub cover began to strongly increase after a decade without fire and was greater on larger plains. Native species richness declined with an increasing minimum interval between fires and increased with elevation. It began to decline at the quadrat scale when shrub cover attained 40%. In the data set as a whole, 17 of the 67 most abundant taxa were absent from all quadrats unburned for 20 years before 2017, indicating a high potential for loss of species at a landscape scale in the absence of fire. Exotic species cover was randomly distributed in relation to fire regimes and environment. The current fire management regime has largely been at a sufficient frequency and minimum interval (approximately a decade between fires) to maintain the grassiness and native species richness of treated plains, which is fortunate given that recent land‐use change appears to have resulted in increased frequency of shrubs independent of their cover.

中文翻译：

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有计划的频繁起火可防止在山地温带草原上继承木本植物的优势

天然温带草原在其整个范围内都受到威胁，这主要是由于它们几乎完全转变为农业，以及由于火灾和放牧制度的变化。灌木丛对木本植物的侵蚀是对草原结构，功能和组成的全球威胁。我们希望确定在萨里山塔斯马尼亚州的温带草原上防止或逆转木本植物入侵，维持原生物种丰富性并最大程度减少外来植物入侵的防火方式的特征，该地区已实施了具有可变处方的消防管理计划已有二十年了。我们在2016/2017年收集了105个四方类（1×10 m）的植物，火情和环境数据，并将2016/2017年的数据与1994年使用相同方法进行的调查相比较。天然灌木的高频率和覆盖特征是2017年之前至少20年未燃烧的区域，但1994年之前的20年未燃烧的区域却没有。灌木覆盖在无火十年后开始急剧增加，在较大的平原上更大。随着火灾之间的最小间隔时间的增加，本地物种的丰富度下降，并随海拔升高而增加。当灌木覆盖率达到40％时，它开始以四方型下降。在整个数据集中，2017年之前20年未燃烧的所有阔脚类群中没有67个最丰富的类群中的17个，这表明在没有火灾的情况下，在景观尺度上物种丧失的可能性很高。外来物种的覆盖与火情和环境有关，是随机分布的。