Abstract
Comparative studies of congeners have been identified as valuable tools to understand why some introduced species become invasive and others do not. I compared individual and population growth characteristics of two annual grasses, invasive Bromus tectorum and naturalized B. briziformis, in greenhouse and field experiments. Smaller pot size, lower water availability and lower rates of nutrient addition all reduced maximum plant size, decreased growth rates, and delayed the period of most rapid plant growth of both species in greenhouse studies. Ontogenetically controlled analyses of biomass allocation revealed that plants had higher root to shoot ratios in less favorable growing conditions (limited soil volume or low nutrient addition), compared to more favorable growing conditions. B. tectorum biomass allocation was more root-heavy compared to B. briziformis biomass allocation in all treatments. Neither species adjusted its allocation to roots in response to water availability but greater root allocation by B. tectorum compared to B. briziformis throughout development may increase the drought tolerance of that species. I used logistic and linear regression analysis of matrix population-model parameters to examine the response of B. tectorum and B. briziformis population growth rates to individual plant nitrogen and water status at two sites. B. tectorum population growth rates were 2 to 3.5 times greater than B. briziformis growth rates across water and nutrient treatments, and across study sites. B. tectorum plants were larger than B. briziformis plants, had lower leaf nitrogen content and produced nearly three times as many seeds as B. briziformis plants. Fertilized plants were larger and produced more seeds than unfertilized plants, but only at one site. Watered plants were more depleted in 13C than unwatered plants only at one site. However, fertilizer and water treatment effects on plant size, seed production, or [delta]13C did not translate into differences in population growth rates. Population growth rates differed only by species and sites.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 15
Claim · model-written summary
Smaller pots, less water, and less nutrient addition reduced maximum size in both species.
- Treatment
- Smaller pot size, lower water availability and lower rates of nutrient additione0
- Outcome
- maximum plant sizee0
- Direction
- reducede0
Not reportedTaxonComparator
Verbatim
e0“Smaller pot size, lower water availability and lower rates of nutrient addition all reduced maximum plant size”
Claim · model-written summary
The three restrictive conditions decreased growth rates.
- Treatment
- Smaller pot size, lower water availability and lower rates of nutrient additione0
- Outcome
- growth ratese0
- Direction
- decreasede0
Not reportedTaxonComparator
Verbatim
e0“Smaller pot size, lower water availability and lower rates of nutrient addition all reduced maximum plant size, decreased growth rates”
Claim · model-written summary
The three restrictive conditions delayed most rapid growth.
- Treatment
- Smaller pot size, lower water availability and lower rates of nutrient additione0
- Outcome
- period of most rapid plant growthe0
- Direction
- delayede0
Not reportedTaxonComparator
Verbatim
e0“Smaller pot size, lower water availability and lower rates of nutrient addition all reduced maximum plant size, decreased growth rates, and delayed the period of most rapid plant growth”
Claim · model-written summary
Limited soil volume or low nutrients increased root to shoot ratios.
Verbatim
e0“plants had higher root to shoot ratios in less favorable growing conditions (limited soil volume or low nutrient addition), compared to more favorable growing conditions”
Claim · model-written summary
B. tectorum allocated more biomass to roots than B. briziformis in every treatment.
- Taxon
- B. tectorum
Bromus tectorume0 - Outcome
- biomass allocatione0
- Direction
- more root-heavye0
- Comparator
- B. briziformise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B. tectorum biomass allocation was more root-heavy compared to B. briziformis biomass allocation in all treatments.”
Claim · model-written summary
Neither species changed root allocation with water availability.
Not reportedTaxonComparatorDirection
Verbatim
e0“Neither species adjusted its allocation to roots in response to water availability”
Claim · model-written summary
B. tectorum population growth was 2 to 3.5 times that of B. briziformis.
- Taxon
- B. tectorumBromus tectorume0
- Outcome
- population growth ratese0
- Direction
- greatere0
- Value
- 2 to 3.5 timese0
- Comparator
- B. briziformise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B. tectorum population growth rates were 2 to 3.5 times greater than B. briziformis growth rates across water and nutrient treatments, and across study sites.”
Claim · model-written summary
B. tectorum plants were larger than B. briziformis.
- Taxon
- B. tectorumBromus tectorume0
- Outcome
- plantse0
- Direction
- largere0
- Comparator
- B. briziformise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B. tectorum plants were larger than B. briziformis plants”
Claim · model-written summary
B. tectorum had lower leaf nitrogen than B. briziformis.
- Taxon
- B. tectorumBromus tectorume0
- Outcome
- leaf nitrogen contente0
- Direction
- lowere0
- Comparator
- B. briziformise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B. tectorum plants were larger than B. briziformis plants, had lower leaf nitrogen content”
Claim · model-written summary
B. tectorum produced nearly three times as many seeds as B. briziformis.
- Taxon
- B. tectorumBromus tectorume0
- Outcome
- seedse0
- Direction
- three times as manye0
- Value
- nearly three timese0
- Comparator
- B. briziformise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B. tectorum plants were larger than B. briziformis plants, had lower leaf nitrogen content and produced nearly three times as many seeds as B. briziformis plants.”
Claim · model-written summary
Fertilization increased plant size at one site.
Verbatim
e0“Fertilized plants were larger and produced more seeds than unfertilized plants, but only at one site.”
Claim · model-written summary
Fertilization increased seed production at one site.
Verbatim
e0“Fertilized plants were larger and produced more seeds than unfertilized plants, but only at one site.”
Claim · model-written summary
Watered plants were more depleted in 13C at one site.
Verbatim
e0“Watered plants were more depleted in 13C than unwatered plants only at one site.”
Claim · model-written summary
Fertilizer and water treatments did not change population growth rates.
- Treatment
- fertilizer and water treatmente0
- Outcome
- population growth ratese0
- Direction
- did not translate into differencese0
Not reportedTaxonComparator
Verbatim
e0“fertilizer and water treatment effects on plant size, seed production, or [delta]13C did not translate into differences in population growth rates”
Claim · model-written summary
Population growth rates differed by species and site.
Not reportedTaxon
Verbatim
e0“Population growth rates differed only by species and sites.”