Aboveground productivity and root-shoot allocation differ between native and introduced grass species

Area of Science:

• Ecology
• Plant Biology
• Ecosystem Functioning

Background:

• Grasslands contain C3 grasses, C4 grasses, and forbs, often categorized as native or introduced.
• Introduced grasses, frequently used for erosion control or grazing, are now common in grasslands.
• Differences in growth and allocation patterns between native and introduced species may impact ecosystem functioning.

Purpose of the Study:

• To compare root and shoot distribution and tissue quality between introduced and native C4 grass species.
• To compare these differences to the divergence between C4 grasses and forbs.
• To assess the ecological significance of native-introduced status in grassland ecosystems.

Main Methods:

• Experimental monocultures of native and introduced C4 grasses were planted in the Blackland Prairie, Texas.
• Comparisons were made using equal-sized transplants on a common soil type and at the same density.
• Root and shoot biomass distribution, tissue quality (C:N ratios), and total Nitrogen were analyzed.

Main Results:

• Native grasses exhibited higher aboveground productivity and C:N ratios than native forbs.
• Native and introduced grasses had similar shallow root biomass and tissue C:N ratios.
• Native grasses had lower aboveground productivity and total N, but greater deep root biomass and root mass fraction compared to introduced grasses.

Conclusions:

• Native-introduced status is a significant factor influencing grassland ecosystem processes like productivity and nitrogen accumulation.
• Differences in biomass allocation and nutrient content between native and introduced grasses can have substantial ecosystem-level impacts.
• Understanding these distinctions is crucial for interpreting the functional roles of different species within grassland communities.