Abstract We analyzed the effects of natural disturbances on relationships between forest regeneration and ungulate browsing. Specifically, we asked if natural disturbances affect preferences of ungulate herbivores towards tree species and size classes; and how local and landscape-scale environmental factors affect spatial patterns of ungulate browsing in disturbed forest ecosystems. Our research was conducted in the Tatra National Park, a mountain range affected by large-scale intense disturbances over the last few decades. We used field data collected in a network of regularly distributed 600 circular sample plots where young trees were recorded and examined for browsing signs. Using forage ratio, the Ivlev’s electivity index and chi square tests, we found that the preferences of wild ungulates were similar to those known from undisturbed forests. Our analyses showed preference for deciduous species, especially rowan, sycamore maple and goat willow. The most common species, Norway spruce was strongly avoided by browsing ungulates. Short saplings from 0.5 m to 1.3 m tall were the most browsed size class. Effects of environmental variables on browsing were analyzed with zero-inflated negative binomial models. The occurrence of browsing was positively related to the total number of young trees and mature tree mortality. This suggests the influence of disturbances on spatial patterns of browsing pressure. The browsing frequency (number of browsed individuals per plot) was affected by mature tree mortality and densities of young palatable trees, including silver fir, sycamore maple and rowan. Elevation, geology, soil type, and potential solar radiation did not show any significant influence on the browsing frequency. Browsing frequency was also positively related to the distance to roads and hiking trails, indicating the role of human pressure upon the behaviour of ungulate herbivores. In addition, we analyzed the effects of accumulation of coarse woody debris (CWD) on browsing frequency and found this relationship to be nonlinear. Analysis for all tree species revealed that at low levels of CWD, the browsing frequency increased with CWD accumulation as a consequence of forest regeneration. However, a large amount of CWD (>25 m3) resulted in a decrease in browsing frequency, and this relationship was species-specific.

中文翻译：

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物种和环境因素对受自然干扰影响的山林幼树浏览频率的影响

摘要 我们分析了自然干扰对森林更新和有蹄类动物觅食之间关系的影响。具体而言，我们询问自然干扰是否会影响有蹄类食草动物对树种和大小等级的偏好；以及当地和景观尺度的环境因素如何影响受干扰的森林生态系统中有蹄类动物的空间格局。我们的研究是在塔特拉国家公园进行的，这是一个在过去几十年中受到大规模强烈干扰影响的山脉。我们使用了在定期分布的 600 个圆形样地网络中收集的现场数据，在这些样地中记录了幼树并检查了浏览标志。使用草料比率、Ivlev 的选择性指数和卡方检验，我们发现野生有蹄类动物的偏好与未受干扰的森林中已知的相似。我们的分析显示偏爱落叶树种，尤其是罗文、梧桐树和山羊柳。最常见的物种挪威云杉被有蹄类动物强烈避免。从 0.5 m 到 1.3 m 高的短树苗是浏览最多的尺寸等级。使用零膨胀负二项式模型分析环境变量对浏览的影响。浏览的发生与幼树总数和成熟树死亡率呈正相关。这表明干扰对浏览压力的空间模式的影响。浏览频率（每个地块浏览的个体数）受成熟树死亡率和幼树密度的影响，包括银冷杉、梧桐树和罗文。海拔、地质、土壤类型、潜在的太阳辐射对浏览频率没有任何显着影响。浏览频率也与到道路和远足小径的距离呈正相关，表明人类压力对有蹄类食草动物行为的影响。此外，我们分析了粗木屑 (CWD) 积累对浏览频率的影响，发现这种关系是非线性的。对所有树种的分析表明，在低水平的 CWD 下，由于森林更新，浏览频率随着 CWD 的积累而增加。然而，大量的CWD（>25 m3）导致浏览频率下降，这种关系是物种特异性的。表明人类压力对有蹄类食草动物行为的作用。此外，我们分析了粗木屑 (CWD) 积累对浏览频率的影响，发现这种关系是非线性的。对所有树种的分析表明，在低水平的 CWD 下，由于森林更新，浏览频率随着 CWD 的积累而增加。然而，大量的CWD（>25 m3）导致浏览频率下降，这种关系是物种特异性的。表明人类压力对有蹄类食草动物行为的作用。此外，我们分析了粗木屑 (CWD) 积累对浏览频率的影响，发现这种关系是非线性的。对所有树种的分析表明，在低水平的 CWD 下，由于森林更新，浏览频率随着 CWD 的积累而增加。然而，大量的CWD（>25 m3）导致浏览频率下降，这种关系是物种特异性的。由于森林更新，浏览频率随着 CWD 的积累而增加。然而，大量的CWD（>25 m3）导致浏览频率下降，这种关系是物种特异性的。由于森林更新，浏览频率随着 CWD 的积累而增加。然而，大量的CWD（>25 m3）导致浏览频率下降，这种关系是物种特异性的。