Solidago altissima

Rim, Hojun, Lee, Minhyun & Song, Uhram, 2023, Mowing inhibits the invasion of the alien species Solidago altissima and is an effective management strategy, Management of Biological Invasions 14 (1), pp. 63-79 : 69-71

Management of S. altissima -dominated community by repeated mowing and eco-friendly herbicide application

The coverages of S. altissima did not differ significantly between 2018 and 2019, regardless of the treatment applied to quadrats ( Figure S2 ). The quadrats that were mowed three times in 2018 had a lower S. altissima coverage in 2019 than in 2018; however, the variance was high and the difference was not statistically significant. Therefore, mowing treatment for 1 year did not affect the coverage of S. altissima , regardless of mowing frequency.

The importance value for S. altissima changed significantly after mowing treatment for 1 year. The importance value for S. altissima was 0.409 in 2018 and decreased to 0.321 in 2019. Consistent results were obtained at all sites subjected to mowing (Table S 5).

In July 2018, 2 months after the first treatment (mowing or Eco200), the height of S. altissima in the mowing group was significantly different from that of the control group, with no difference in the height of S. altissima between the Eco 200 treatment and control group (Table S 6). After 1 year of mowing or Eco 200 treatment, in April 2019, the height of the dead shoots differed significantly between the control group and the Mowing 1, Mowing 2, and Mowing 3 groups ( Table 1). In particular, the average heights in the Mowing 2 and Mowing 3 groups were one-tenth that of the control group ( Table 1). However, the height of the dead shoots in the Eco 200 group was not significantly different from that in the control group and was larger than those in the mowing treatment groups.

We continued the experiment to determine the effects of mowing on the growth of S. altissima in 2019. We measured the height of shoots of S. altissima in May, July, and September, before each mowing treatment. The height of the shoot already differed between the control and Mowing 2 or Mowing 3 groups in May 2019, before mowing ( Table 2). Height did not differ between the Mowing 1 and control groups. In July, heights in the Mowing 2 and Mowing 3 groups were significantly different from that in the control group, with no difference between the Mowing 1 and control groups (Table S 7). In September, heights in all treatment groups were significantly different from that in the control group ( Table 3).

The number of shoots of S. altissima did not differ significantly between groups in March 2018 before the experiment started ( Figure 2 ). After 1 year of mowing or Eco 200 treatment, the number of shoots of S. altissima was significantly lower in the Mowing 3 group than in the control group in April 2019 ( Figure 2 ). Mowing 1, Mowing 2, and Eco 200 treatments did not reduce the number of shoots compared with the number observed in the control group.

The number of leaves was lower in mowing treatment groups than in the control group (Table S 8). Mowing 3 (mowed twice before harvesting) had the fewest leaves between the control and treatment groups. The aboveground biomass of S. altissima was also significantly lower in the mowing treatment groups than in the control group. However, there were no significant differences between mowing treatments ( Figure 3a ).

The biomass of rhizomes was significantly affected by mowing treatment and by the frequency of mowing after 2 years ( Figure 3b ). Plants subjected to mowing once a year had 933.6 g /m 2 rhizomes, similar to the rhizome content of control plants (987.7 g /m 2). However, plants that were mowed two or three times had 732.0 g/m 2 or 535.3 g /m 2 rhizomes, respectively, which were significantly lower than the estimate for control plants.

Figures

Figure 2. Number of shoots of S. altissima in March 2018 and April 2019. Mowing 1: mowed once in July; Mowing 2: mowed twice in May and September; Mowing 3: mowed three times in May, July, and September; Eco 200: 30% of shoots in the quadrats were cut near the ground, and the cut surfaces were covered with Eco 200 block. Data are presented as means ± standard errors of 14 replicates. Bars with different letters are significantly different at p <0.05 (ANOVA with post hoc Tukey’s test).

Figure 3. (a) Aboveground biomass of S. altissima in September 2019. (b) Biomass of rhizomes of S. altissima in September 2019. Mowing 1: mowed once in July; Mowing 2: mowed twice in May and September; Mowing 3: mowed three times in May, July, and September. Data are presented as means ± standard errors of 14 replicates. Bars with different letters are significantly different at p <0.05 (ANOVA with post hoc Tukey’s test).