Abstract
Giant ragweed (Ambrosia trifida, L. henceforth referred to as GR), an annual non‐native invasive weed, may cause health problems and can reduce agricultural productivity. Chemical control of GR in grasslands may have irreversible side effects on herbs and livestock. In an attempt to propose a solution to the harmful effects of GR on grasslands, this study explores the fate of its soil seed bank (SSB) and considers the physical control of its SSB reduction.By studying GR distributed in grasslands of the Yili Valley, Xinjiang, China, we measured the spatial and temporal changes in seed density, seed germination, dormancy, and death. We analyzed seed germination, dormancy, and death following different storage periods. The study analyzed population characteristics over time, including seed fate, and examined physical control methods for reducing the SSB density.The SSB of GR occurs in the upper 0–15 cm of soil in grasslands. Seed density in the SSB decreased by 68.1% to 82.01% from the reproductive growth period to the senescence period. More than 98.7% of the seeds were rotten, eaten, germinated, dispersed, or died within one year after being produced. The seed germination rate of the SSB decreased with the number of years after invasion. When stored for 0.5 or 3.5 years, seed germination rates fell by 40%, during which time seed death rate increased by almost 40%. When GR was completely eradicated for two consecutive years, the SSB and population densities decreased by >99%.The vast majority of GR seeds germinated or died within one year; the germination rate decreased significantly if the seeds were stored dry at room temperature for a long time. Newly produced seeds are the main source of seeds in the SSB. Therefore, thoroughly eradicating GR plants for several years before the seeds can mature provides an effective control method in grasslands.
Highlights
| 4856 density occur during different years after invasion in grasslands? (3) What are the characteristics of seed germination, seed dormancy, and seed death in the soil seed bank (SSB) in different years and following different periods of storage? (4) Can we control GR more effectively by reducing the SSB density in grasslands?
The highest SSB density in grasslands was 14,200 grain m−2 at six years after invasion (Figure 3), which is much higher than the SSB in farmlands (Goplen, 2015; Goplen et al, 2016; Page & Nurse, 2015)
The SSB density had become more uniform by six years after invasion (Figure 3)
Summary
Giant ragweed propagates exclusively by seeds (Rasmussen et al, 2017) This annual plant uses an r-strategy during reproduction, featuring rapid development, a large proportion of reproductive allocation, a short generation cycle, and production of a large number of individuals. It is meaningful to research the germination characteristics of GR seeds in the SSB during different invasion years and to consider possible physical controls for SSB reduction. This study considers whether we can prevent the introduction of GR and control GR by reducing the SSB density via physical methods. The seed fate in this study refers to the characteristics of SSB density, seed germination, seed dormancy, and seed death in different soil layers and during different years after the invasion of GR. | 4856 density occur during different years after invasion in grasslands? (3) What are the characteristics of seed germination, seed dormancy, and seed death in the SSB in different years and following different periods of storage? (4) Can we control GR more effectively by reducing the SSB density in grasslands?
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