1. EFFECTIVENESS AND LONGEVITY OF BUFFELGRASS TREATMENTS IN SAGUARO NATIONAL PARK Molly Hunter Assistant Research Professor Northern Arizona University, School of Forestry Molly.hunter@nau.edu

2. Objectives Assess the effectiveness of different buffelgrass control treatments (i.e. manual pulling, herbicide application) Determine how buffelgrass treatment effectiveness is impacted by factors such as treatment timing, treatment frequency, and site characteristics

3. Saguaro National Park Examined treatments from 2006 – 2010 Data collected in 2010 Two types of treatments Herbicide only Manual pulling followed by herbicide Two treatment seasons Winter (October – May) Summer (June – September)

4. Rincon Mountain DistrictTucson Mountain District

5. Treatment regime Treatment type Number of patches Description Three consecutive treatments Chemical15 Three herbicide treatments occurring in consecutive seasons. Three consecutive treatments Chemical + manual 11 Three treatments (one manual followed by two herbicide) occurring in consecutive seasons. Two consecutive seasons Chemical28 Two herbicide treatments occurring in consecutive seasons. Two consecutive seasons Chemical + manual 15 Two treatments (one manual followed by one herbicide) occurring in consecutive seasons. One skipped seasonChemical15 Two herbicide treatments occurring in nonconsecutive season (one winter or summer season skipped) One skipped season Chemical + manual 10 Two treatments (on manual followed by one herbicide) occurring in two nonconsecutive seasons (one winter or summer season skipped) Two skipped seasonsChemical12Two herbicide treatments occurring in nonconsecutive seasons (one winter season and one summer season skipped)

6. Other variables Rainfall (total rainfall 1 month prior to treatment) Aspect (N, S, E, W) Time since last treatment (months) Slope (%)

7. Response variables Current density (individuals m -2 ) Current coverage (m 2 – percent cover X patch size) Percent change in patch size (time of first treatment compared to summer 2010) Percent change in density Percent change in coverage

8. Statistics Categorical variables Non-parametric tests (van der Waerden chi square, Wilcoxon test) Continuous variables Spearman’s correlation

9. Results Change in patch size was lowest when two seasons were skipped No other variables impacted by treatment regime

10. Results Current buffelgrass coverage and density were lower in manual + herbicide treatments compared to herbicide only

11. Results Percent change in patch size was lower on south- facing aspects

12. Results Current buffelgrass density and coverage were higher on south-facing aspects

13. Results Percent slope was negatively correlated with change in patch size (-0.24) and change in density (-0.30) Percent slope was positively correlated with current density (0.32) and current coverage (0.35)

14. Results Rainfall was positively correlated with percent change in coverage (0.27) Rainfall was negatively correlated with current density (- 0.23) and current coverage (-0.20)

15. Uncertainties Time since last treatment was not significant, but time frame of study was short Distance to roads/trails/drainages, soil type, and temperature not assessed Influence of original patch size, cover and density not assessed

16. Conclusion Most plots showed reductions in patch area greater than 90% Skipping two full treatment seasons (one winter and one summer) may result in less successful control of buffelgrass Combination treatments may be slightly more effective than herbicide only treatments Buffelgrass abundance measures were consistently higher on south-facing aspects Buffelgrass treatments were less effective on steep slopes

17. Acknowledgements Dana Backer and Perry Grissom (SNP) Leigh Perry (UA) NPS Fuels Reserve Fund