Saltcedar (Tamarix spp.) in the Northern Great Plains: Seed Ecology and Cultural Considerations

Saltcedar (Tamarix spp.) is becoming more commonplace within riparian habitats of the Northern Great Plains (NGP) and has been given “noxious weed” status in many of the states in this region. Little information on the environmental conditions conducive to the establishment of saltcedar specific to this region exists, however. In addition to biological implications, there is little to no understanding as to the sociological impacts of a saltcedar invasion. Therefore, three separate studies were conducted to 1) evaluate saltcedar seed ecology dynamics in a controlled growing chamber setting, 2) assess the seasonality of saltcedar seedlings in the northern Great Plains (NGP), and 3) to determine native Lakota cultural viewpoints of saltcedar and its impacts on the tribes in South Dakota. The first study evaluated saltcedar seedling emergence in conditions found in riparian habitats of the Great Plains. Growth chamber experiments evaluated the effects of soil moisture, soil sterilization, and vegetation cover on saltcedar seedling emergence in two soil types (clayey and sandy) and with seed from two locations in western South Dakota. Emergence increased with increasing soil moisture and was consistently higher in clayey than in sandy soils. Soil sterilization and grass cover decreased seedling emergence, and emergence differed between seed sources. In the second study, seasonality of saltcedar (Tamarix spp.) seedling emergence was monitored in two sites in western South Dakota as related to soil moisture, light availability, and distance from seed source. In June 2011, a total of 120 plots were established in each of three moisture levels (40 plots per level) at each site. Moisture levels were categorized as: 1) wettest, 2) moderate, and 3) driest and were determined based upon topography (slight differences in elevation), distance from nearest standing water and/or the presence of wetland-obligate vegetation at the time of plot establishment. Light availability and distance to the nearest seed source were measured at each plot. The moderate moisture level had the highest number of newly emerged seedlings at the beginning of seedling emergence (mid-July) at both sites, but after that, there was little or no difference in seedling emergence among the moisture levels. Seedling mortality was high; in general 54% of seedlings died within 2 weeks of emerging and only 31% of total emergents remained at the end of the growing season (end of September). Seedling survival was highest in the moderate moisture level (p ≤0.06). Seedling emergence and survival were significantly related to light availability at both sites (p ≤0.06), but to distance from seed source at only one site. However, seedling emergence and survival were not strongly related to either of these factors at either site (all r ≤ 0.39). Ecological effects of saltcedar are widely investigated; little attention is given to cultural considerations. Invasive species can and do affect social and cultural systems in a myriad of ways, usually culturally specific. Therefore, the goal of the final study, through the avenue of interviews, was to gain understanding of the current and possible effects and concerns of saltcedar on the Lakota culture. Interviewed participants were members of a South Dakota federally recognized tribe and/or residents of a South Dakota, Lakota reservation. A priority was to obtain feedback from various internal groups and subgroups. These groups are defined as: 1) ranchers, a) land owners, b) land leasers; 2) traditional practitioners (This included but was not limited to those who regularly participate in cultural and spiritual practices, speak their native language, etc…) and; 3) resource managers, a) park and recreation, b) tribal land officials. Three participants were purposely selected to represent each sub-category, giving a total of 15 interviewees. Three main themes were highlighted from the participant’s responses, stressing concern for 1) culturally significant vegetation, 2) ranching endeavors, and 3) land management time and resources. Emphasizing these concerns can significantly contribute to education about saltcedar and management efforts. An understanding of how saltcedar infestations affect the Lakota culture enhances efforts at environmental and cultural conservation