Reducing invasive species abundance near the leading edge of invasions is important for maintaining diverse, high-functioning ecosystems, but it can be hard to remove invasives present at low levels within desirable plant communities. Focusing on an invasive annual grass, Bromus tectorum, near the edge of its range in the southern Colorado Plateau, we used an observational study to ask what plant community components were associated with lower levels of B. tectorum, and a manipulative experiment to ask if targeted spring grazing or seeding native competitors were effective for reversing low-level invasion. The observational study found that higher C₃ perennial grass cover and shrub cover were associated with lower B. tectorum abundance, and adult Poa fendleriana and Pascopyrum smithii plants had the fewest B. tectorum individuals within 50 cm. Our manipulative experiment used a randomized, hierarchical design to test the relative effectiveness of seeding native perennial grasses using different spatial planting arrangements, seeding rates, seed enhancements, and targeted spring grazing. Two years after seeding, seeded species establishment was 36% greater in high seed rate than unseeded plots, and high rate plots also had lower B. tectorum cover. One season after targeted spring grazing (a single, 2-week spring-grazing treatment 17 months post-seeding), grazed paddocks displayed trends towards higher seeded species densities and lower B. tectorum biomass in certain seeding treatments, compared to ungrazed paddocks. Results suggest high rate native grass seedings may be effective and short-duration spring grazing should be further evaluated as potential tools for preventing ecosystem conversion along invasion fronts.

减少入侵前沿附近的入侵物种数量对于维持多样化的高功能生态系统很重要，但要清除理想植物群落中低水平的入侵物种可能很难。针对科罗拉多州南部高原范围边缘附近的入侵性一年生禾草Bromus tectorum，我们进行了一项观察性研究，询问哪些植物群落成分与较低水平的B. tectorum相关，并进行了操作性实验以询问是否有针对性的春季放牧或为当地竞争对手播种可有效逆转低度入侵。观察性研究发现，较高的C ₃多年生草覆盖率和灌木覆盖率与较低的B. tectorum有关。丰度，成年的Poa fendleriana和Pascopyrum smithii植物在50 cm内有最少的B. tectorum个体。我们的操纵性实验使用了随机的，分层的设计，以测试使用不同空间种植安排，播种率，种子增强和有针对性的春季放牧的多年生草播种的相对有效性。播种后两年，高种子率的种子物种建立比未播种的地块高36％，高速率的地块也有较低的鹤望兰覆盖。在有针对性的春季放牧后的一个季节（播种后17个月进行一次为期2周的春季放牧处理）后，放牧的牧场呈现出更高的播种密度和更低的趋势。B. tectorum生物质在某些播种疗法相比，ungrazed围场。结果表明，高比率的天然草木播种可能是有效的，短时春季放牧应进一步评估，作为防止沿入侵前沿的生态系统转化的潜在工具。