Abstract
Abstract Background The Eurasian steppe is an important vegetation type characterized by cold, arid and nitrogen poor conditions. At the Eastern edge, including in the Songnen grassland, the vegetation is dominated by Leymus chinensis (henceforth L. chinensis ) and is increasing threatened by elevated anthropogenic nitrogen deposition. L. chinensis is a perennial grass that mainly reproduces vegetatively and its sexual reproduction is limited. However, sexual reproduction plays an important role influencing colonization after large disturbances. To develop an understanding of how elevated nitrogen deposition changes the plant community structure and functioning we need a better understanding how sexual reproduction of L. chinensis changes with nitrogen enrichment. Here we report on a field experiment where we added 10 g N m − 2 yr − 1 and examined changes in seed traits, seed germination and early seedling growth. Results Nitrogen addition increased seed production by 79%, contributing to this seed increases were a 28% increase in flowering plant density, a 40% increase in seed number per plant and a 11% increase in seed weight. Seed size increased with a 42% increase in large seeds and a 49% decrease in the smallest seed size category. Seed germination success improved by 10% for small seeds and 18% for large seeds. Combined, the increased in seed production and improved seed quality doubled the potential seed germination. Subsequent seedling above and below-ground biomass also significantly increased. Conclusions All aspects of L. chinensis sexual reproduction increased with nitrogen addition. Thus, L. chinensis competitive ability may increase when atmospheric nitrogen deposition increases, which may further reduce overall plant diversity in the low diversity Songnen grasslands.
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Claims 10
Claim · model-written summary
Nitrogen addition increased seed production by 79%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additione0
- Outcome
- seed productione0
- Direction
- increasede0
- Value
- 79%e0
Not reportedComparator
Verbatim
e0“Nitrogen addition increased seed production by 79%”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Nitrogen addition increased flowering plant density by 28%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- flowering plant densitye0
- Direction
- increasee0
- Value
- 28%e0
Not reportedComparator
Verbatim
e0“a 28% increase in flowering plant density”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Nitrogen addition increased seed number per plant by 40%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- seed number per plante0
- Direction
- increasee0
- Value
- 40%e0
Not reportedComparator
Verbatim
e0“a 40% increase in seed number per plant”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Nitrogen addition increased seed weight by 11%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- seed weighte0
- Direction
- increasee0
- Value
- 11%e0
Not reportedComparator
Verbatim
e0“a 11% increase in seed weight”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Nitrogen addition increased large seeds by 42%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- large seedse0
- Direction
- increasee0
- Value
- 42%e0
Not reportedComparator
Verbatim
e0“a 42% increase in large seeds”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Nitrogen addition decreased the smallest seed size category by 49%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- smallest seed size categorye0
- Direction
- decreasee0
- Value
- 49%e0
Not reportedComparator
Verbatim
e0“a 49% decrease in the smallest seed size category”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Small-seed germination improved by 10%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- Seed germination successe0
- Direction
- improvede0
- Value
- 10%e0
- Qualifier
- small seedse0
Not reportedComparator
Verbatim
e0“Seed germination success improved by 10% for small seeds and 18% for large seeds.”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Large-seed germination improved by 18%.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- Seed germination successe0
- Direction
- improvede0
- Value
- 18%e0
- Qualifier
- large seedse0
Not reportedComparator
Verbatim
e0“Seed germination success improved by 10% for small seeds and 18% for large seeds.”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Potential seed germination doubled.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- potential seed germinatione0
- Direction
- doublede0
Not reportedComparator
Verbatim
e0“Combined, the increased in seed production and improved seed quality doubled the potential seed germination.”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
Claim · model-written summary
Seedling above-ground biomass significantly increased.
- Taxon
- Leymus chinensisLeymus chinensist0
- Treatment
- Nitrogen additiont1
- Outcome
- seedling above and below-ground biomasse0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Subsequent seedling above and below-ground biomass also significantly increased.”
t0“Leymus chinensis”
t1“Nitrogen addition increases sexual reproduction and improves seedling growth in the perennial rhizomatous grass Leymus chinensis”
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See all 14 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.