Broad‐scale threats to floristic diversity in native temperate grasslands are well‐documented and include elevated soil nutrients, changes in disturbance regimes and exotic species. However, fine‐scale variables associated with the presence of native forbs, such as gap size and biomass cover, have received relatively little attention. We conducted a case–control study to determine the relative influence of physical structural dimensions and other fine‐scale variables associated with the presence of native forbs in a modified temperate grassland previously used for domestic grazing. We matched 145 case plots centred on 27 different species of native forbs with 290 control plots not centred on a native forb. For each percentage increase in ground litter cover, dead biomass cover, grass cover or exotic forb cover, or the area of bare ground within 30 cm, the relative odds that a native forb was present vs absent declined by a mean of 10–13%. Living and dead biomass reduces light availability, and the former can also reduce nutrient and water availability. Declines in the presence of native forbs associated with increasing total bare ground may suggest that gap sizes were too small or the soil surface condition too degraded. Our results add to a body of evidence suggesting that native forbs in temperate native grassland are likely to benefit from periodic removal of living and dead grass biomass and a reduction in the cover of exotic forbs.

中文翻译：

---

与天然温带草原中原生草存在相关的精细尺度变量

有证据表明，原生温带草原对植物多样性的广泛威胁包括升高的土壤养分，干扰状况的变化和外来物种。但是，与天然福布斯相关的小规模变量，例如缺口大小和生物量覆盖率，却很少受到关注。我们进行了病例对照研究，以确定物理结构尺寸和其他精细尺度变量的相对影响，这些变量与先前用于家庭放牧的改良温带草原中原生草的存在相关。我们将以27种不同种类的原生动物为中心的145个案例地块与没有以原生动物为中心的290个对照地块进行了匹配。地面垃圾覆盖，生物量死亡覆盖，草覆盖或异国情调的森林覆盖每增加一个百分比，或30厘米以内的裸露区域，存在或不存在本机前叉的相对几率平均下降了10-13％。生活的生物量和死生物量会降低光的利用率，而前者也会降低养分和水的利用率。与自然裸露地面的增加相关的天然前叉的减少可能表明，缝隙尺寸太小或土壤表面状况过差。我们的结果增加了大量证据，表明温带天然草原中的原生草可能会受益于定期清除活草和枯草生物量以及减少外来草的覆盖。与天然裸露地面的增加相关的天然前叉的减少可能表明间隙大小过小或土壤表面状况过差。我们的研究结果增加了大量证据，表明温带天然草地上的原生草可能会因定期清除活草和枯草生物量以及减少外来草的覆盖而受益。与自然裸露地面的增加相关的天然前叉的减少可能表明，缝隙尺寸太小或土壤表面状况过差。我们的研究结果增加了大量证据，表明温带天然草地上的原生草可能会因定期清除活草和枯草生物量以及减少外来草的覆盖而受益。