Blossey Bernd, Dávalos Andrea, Nuzzo Victoria
Department of Natural Resources, Fernow Hall, Cornell University, Ithaca, NY 14853, USA.
Natural Area Consultants, 1 West Hill School Road, Richford, NY 13835, USA.
AoB Plants. 2017 Jul 22;9(5):plx034. doi: 10.1093/aobpla/plx034. eCollection 2017 Sep.
Management of ungulates is contested ground that lacks stakeholder agreement on desirable population sizes and management approaches. Unfortunately, we often miss information about extent of local impacts, for example on plant communities, to guide management decisions. Typical vegetation impact assessments like the woody browse index do not assess herbaceous plants, and differences in browse severity can be a function of deer density, deer legacy effects, localized deer feeding preferences and/or differences in plant community composition. Furthermore, in heavily affected areas, few remnant plants may remain for assessments. We used a sentinel approach to assess impact of white-tailed deer (), rodent attack, invasive earthworms and three invasive plants on survival and growth of 3-month-old red oak () individuals. We planted cohorts in 2010 and 2011 into deer accessible and fenced 30 × 30 m plots at 12 forests in New York State. We found year and site-specific effects with high deer herbivory of unprotected individuals (70-90 % of oaks browsed by deer versus none in fenced areas) far exceeding importance of rodent attacks. Oaks planted at low earthworm density sites were at significantly higher risk of being browsed compared with oaks at high earthworm density sites, but there was no detectable negative effect of invasive plants. Surviving oaks grew (~2 cm per year) under forest canopy cover, but only when fenced. We consider planting of oak or other woody or herbaceous sentinels to assess deer browse pressure a promising method to provide quantifiable evidence for deer impacts and to gauge success of different management techniques. The strength of this approach is that typical problems associated with multiple stressor impacts can be avoided, areas devoid of forest floor vegetation but under heavy deer browse pressure can still be assessed and the method can be implemented by non-specialists. Implementation of regular assessments can guide ungulate management based on meaningful evidence.
有蹄类动物的管理是一个充满争议的领域，利益相关者在理想的种群规模和管理方法上未能达成共识。遗憾的是，我们常常缺乏有关局部影响程度的信息，例如对植物群落的影响，从而无法指导管理决策。像木本植物啃食指数这样的典型植被影响评估并未对草本植物进行评估，而且啃食严重程度的差异可能取决于鹿的密度、鹿的遗留效应、局部的鹿食性偏好和/或植物群落组成的差异。此外，在受影响严重的地区，可能几乎没有剩余植物可供评估。我们采用了一种哨兵监测方法，来评估白尾鹿、啮齿动物啃咬、入侵蚯蚓和三种入侵植物对3个月大的红橡树个体存活和生长的影响。我们在2010年和2011年将几组红橡树幼苗种植到纽约州12个森林中可被鹿进入的以及用围栏围住的30×30米的地块里。我们发现了年份和地点特异性效应，未受保护个体遭受的鹿的高强度啃食（70 - 90%的橡树被鹿啃食，而围栏区域内没有）远远超过了啮齿动物啃咬的影响。与种植在蚯蚓密度高的地点的橡树相比，种植在蚯蚓密度低的地点的橡树被啃食的风险显著更高，但入侵植物没有可检测到的负面影响。存活下来的橡树在森林树冠覆盖下生长（每年约2厘米），但只有在围栏保护下才如此。我们认为种植橡树或其他木本或草本哨兵植物来评估鹿的啃食压力是一种很有前景的方法，可以为鹿的影响提供可量化的证据，并衡量不同管理技术的成效。这种方法的优势在于，可以避免与多种压力源影响相关的典型问题，仍然能够评估那些没有森林地表植被但鹿啃食压力大的区域，而且该方法非专业人员也可实施。定期评估的实施可以基于有意义的证据来指导有蹄类动物的管理。
