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 : 65-66

Management of S. altissima -dominated communities by repeated mowing and eco-friendly herbicide use

Large quadrats (300 m 2) were established in the areas dominated by S. altissima at sites 1–7. Ten small quadrats (2 × 2 m, with a 50 cm buffer zone on all sides) were established within large quadrats at each site. Figure S1 shows an example of the quadrat arrangement. Quadrats were randomly assigned to two sets of control (untreated), Mowing 1 (mowed once in July), Mowing 2 (mowed twice in May and September), Mowing 3 (mowed three times in May, July, and September), or Eco 200 treatments; thus there were 14 replicates for each treatment (7 sites × 2 replicates). As previous vegetation monitoring of Jeju island showed, this mowing frequency was common for most green space managed by the local government ( Song 2016). For Eco 200 treatments, 30% of S. altissima shoots were cut near the ground and the cut surface was covered by Eco 200 block, as instructed by the manufacturer (Eco Industry Inc., Pyeongtaek, Korea). Eco 200 is a small, round clay-type block that contains aglycones, an eco-friendly herbicide. Eco 200 was applied three times, in May, July, and September.

Shoots of S. altissima within small quadrats (2 × 2 m) were counted in March 2018, before the experiment. Shoots of S. altissima in each treatment group were then counted in April 2019. The vegetation and coverage of S. altissima in the control or treated quadrats were also investigated in July 2018 (before the experiment) and 2019 (after 1 year of the experiment), following the method described in section 2.2. We measured the height of S. altissima shoots to determine the effects of repetitive mowing on plant growth. The height of S. altissima was measured in July 2018 and April 2019 in the first-year experiments, and in May, July, and September 2019 in the second-year experiments. Each measurement was performed before the mowing application.

The aboveground biomass of S. altissima was measured in September 2019 before the last mowing. We harvested and weighed S. altissima shoots in a small 40 × 40 cm quadrat inside every experimental quadrat. Leaves on five randomly selected individuals were also counted. The effect of mowing frequency on the biomass of rhizomes of S. altissima was also evaluated. In June and July 2020, after digging a 40 × 40 cm wide area to a depth of 15 cm, rhizomes of S. altissima inside the experimental quadrat were harvested. The soil was cleaned from the harvested rhizomes and the biomass was weighed. Finally, the effect of mowing on the reproductive characteristics of S. altissima was determined by estimating flowering rates in October 2019. Five individuals were randomly chosen in the quadrats of each treatment for the investigation of the presence of flowers.

Figures

Figure 1. (a) Coverage of S. altissima and (b) the average number of species per quadrat in the S. altissima-dominant areas or uninvaded areas. Data are presented as means ± standard errors of 14 replicates. Bars with different letters are significantly different at p <0.05 (Student’s t-test).