More info for the terms:
density,
litter,
rhizome,
seed,
stratificationCommon river grass regenerates and spreads primarily by shallow rhizomes. In
North Dakota, a road grader removed the vegetation from a site dominated
by hardstem bulrush (Scirpus acutus). The following growing season, the
cleared area was dominated by common river grass with 90 stems per square foot
(998 stems/sq m) while water was still 16 inches (40 cm) deep. Common river grass
regenerated from rhizomes in the substrate [
36].
Although common river grass generally produces abundant seeds, it does so only if
wetlands contain water early in the spring [
18]. Seeds are dispersed by
water movement and accumulate in the seedbank [
34,
43].
Smith [
38] tested the effects of stratification temperatures and times
on germination of wet and dry common river grass seeds. Results were variable.
Galinato and van der Valk [
11] reported that stratification does not
improve common river grass germination.
Seed burial, which occurs with inundation, is required for common river grass
emergence. Anaerobic conditions stimulate fermentation which increases
the germination rate. In summer, anaerobic conditions increase as water
levels decrease and potholes stagnate. Seeds, which have been
stimulated by early season anaerobic conditions, germinate when light
reaches the substrate and the ground is no longer submerged [
11,
36]. A
seed burial depth of 0.4 inches (1 cm) maximizes emergence and seedling
length and weight [
38]. Seedlings can reach the soil surface from a
maximum depth of 2 inches (5 cm) [
11]. Smith [
36] found no seedlings in
areas with heavy litter accumulation.
Few common river grass seedlings become established. A seedling must have a
rhizome to survive the winter. Seedlings produce a rhizome 30 to 60
days after emergence. The window of time between germination and
dormancy is often too short to produce a rhizome [
36].
Merendino and others [
29,
30] investigated common river grass establishment and
success on artificially created mudflats subject to reflooding 1 year
later at different depths. Mudflats were created at four drawdown
dates: May 15, June 15, July 15, and August 15. Seedling density,
measured on August 30, was highest with the June 15 and July 15
drawdowns. The soil may have been too cold for germination in May. The
plots were reflooded the following May with four depths: 0, 6, 12, and
20 inches (0, 15, 30, and 50 cm). By August 30, most 1-year-old
common river grass seedlings had died with 12 inches (30 cm) or more of continuous
flooding [
29,
30].
McKee and others [
28] investigated root metabolic response of common river grass
to flooding. Common river grass has insufficient air space development in the
roots to allow complete aerobic metabolism during prolonged flooding.
It is not as tolerant of flooding as hybrid cattail (Typha glauca),
hardstem bulrush, softstem bulrush (Scirpus validus), or common reed [
28].