While invasive plant distributions are relatively well known in the eastern United States, temporal changes in species distributions and interactions among species have received little attention. Managers are therefore left to make management decisions without knowing which species pose the greatest threats based on their ability to spread, persist and outcompete other invasive species. To fill this gap, we used the U.S. National Park Service’s Inventory and Monitoring Program data collected from over 1,400 permanent forest plots spanning 12 yr and covering 39 eastern national parks to analyze invasive plant trends. We analyzed trends in abundance at multiple scales, including plot frequency, quadrat frequency, and average quadrat cover. We examined trends overall, by functional group, and by species. We detected considerably more increasing than decreasing trends in invasive plant abundance. In fact, 80% of the parks in our study had at least one significant increasing trend in invasive abundance over time. Where detected, significant negative trends tended to be herbaceous or graminoid species. However, these declines were often countered by roughly equivalent increases in invasive shrubs over the same time period, and we only detected overall declines in invasive abundance in two parks in our study. Present in over 30% of plots and responsible for the steepest and greatest number of significant increases, Japanese stiltgrass (Microstegium vimineum) was the most aggressive invader in our study and is a high management priority. Invasive shrubs, especially Japanese barberry (Berberis thunbergii), Japanese honeysuckle (Lonicera japonica), multiflora rose (Rosa multiflora), and wineberry (Rubus phoenicolasius), also increased across multiple parks, and sometimes at the expense of Japanese stiltgrass. Given the added risks to human health from tick‐borne diseases, invasive shrubs are a high management priority. While these findings provide critical information to managers for species prioritization, they also demonstrate the incredible management challenge that invasive plants pose in protected areas, particularly since we documented few overall declines in invasive abundance. As parks work to overcome deferred maintenance of infrastructure, our findings suggest that deferred management of natural resources, particularly invasive species, requires similar attention and long‐term commitment to reverse these widespread increasing invasive trends.

中文翻译：

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长期趋势表明，入侵性植物在东部国家公园中无处不在并在增加

尽管在美国东部，入侵植物的分布相对众所周知，但是物种分布的时间变化和物种间的相互作用却鲜有受到关注。因此，管理人员只能根据其传播，持久和胜过其他入侵物种的能力，不知道哪个物种构成最大威胁，来做出管理决定。为了填补这一空白，我们使用了美国国家公园管理局的清单和监测计划数据，该数据是从12年中覆盖了39个东部国家公园的1,400多个永久性森林地块中收集的，用于分析入侵植物的趋势。我们分析了多个标度的丰度趋势，包括标绘频率，二次方频率和平均二次方覆盖率。我们按功能组和物种检查了总体趋势。我们发现入侵植物丰度的增加趋势远大于下降趋势。实际上，在我们的研究中，随着时间的推移，入侵公园的公园中至少有80％的公园具有显着增加的趋势。在检测到的地方，显着的负趋势往往是草本或类蠕虫。但是，这些下降通常可以通过在同一时期内入侵灌木丛大致相等的增长来抵消，并且我们在我们的研究中仅检测到两个公园中入侵物种丰度的总体下降。日本矮脚草（占30％以上的地块）是造成最大幅度和最大幅度显着增长的原因。显着的负面趋势往往是草本或类粉虱物种。但是，这些下降通常可以通过在同一时期内入侵灌木丛大致相等的增长来抵消，并且我们在我们的研究中仅检测到两个公园中入侵物种丰度的总体下降。日本矮脚草（占30％以上的地块）是造成最大幅度和最大幅度显着增长的原因。显着的负面趋势往往是草本或类粉虱物种。但是，这些下降通常可以通过在同一时期内入侵灌木丛大致相等的增长来抵消，并且我们在我们的研究中仅检测到两个公园中入侵物种丰度的总体下降。日本矮脚草（占30％以上的地块）是造成最大幅度和最大幅度显着增长的原因。Microstegium v​​imineum）是我们研究中最具侵略性的入侵者，是高度管理的重点。外来灌木，特别是日本伏牛花（Berberis thunbergii），日本金银花（Lonicera japonica），何首乌蔷薇（Rosa multiflora）和酒berry（Rubus phoenicolasius）），而且在多个公园中都有所增加，有时以日本矮脚草为代价。由于tick传播疾病给人类健康带来的额外风险，侵入性灌木丛是高度管理的重点。尽管这些发现为管理人员提供了有关物种优先次序的关键信息，但它们也证明了入侵植物在保护区带来的难以置信的管理挑战，特别是因为我们记录到入侵性丰度总体下降很少。随着公园努力克服对基础设施的延期维护，我们的发现表明，对自然资源（尤其是入侵物种）的延期管理需要类似的关注和长期承诺，以扭转这些广泛增长的入侵趋势。