Invasive, non-native plant species can directly affect native plants by monopolizing or controlling limiting resources, and change ecosystems by altering soil stability, colonizing open substrates, promoting erosion, affecting the accumulation of litter or other soil resources, and altering natural fire regimes. Invasive species are a concern to parks because they threaten the genetic integrity of native flora through hybridization, and can change the structure and function of ecosystems through alterations of geochemical and
In the past few decades, non-native invasive species have increased exponentially in Alaska and around the park. Sitka is susceptible to continual invasions by non-native plant taxa because many different plant species thrive in the mild climate of Southeast Alaska. There are several pernicious species that have been recently introduced to Sitka (e.g., snow-in-summer [Cerastium tomentosum] in 2006 and perennial sow thistle [Sonchus arvensis] in 2007). Therefore, regular monitoring and eradication projects are essential in reducing and eradicating encroaching invasive species.
The NPS Exotic Plant Management Team (EPMT), park staff, and participants in AmeriCorps Tribal Civilian Community Corps (TCCC) conduct continual control efforts on Japanese knotweed (Fallopia japonica) and other invasive plant species.