Community- And Ecosystem-Level Changes in a Species-Rich Tallgrass Prairie Restoration

Abstract

Changes in the plant community and ecosystem properties that follow the conversion of agriculture to restored tallgrass prairies are poorly understood. Beginning in 1995, we established a species‐rich, restored prairie chronosequence where ∼3 ha of agricultural land have been converted to tallgrass prairie each year. Our goals were to examine differences in ecosystem properties between these restored prairies and adjacent agricultural fields and to determine changes in, and potential interactions between, the plant community and ecosystem properties that occur over time in the restored prairies. During the summers of 2000–2002, we examined species cover, soil C and N, potential net C and N mineralization, litter mass, soil texture, and bulk density across the 6‐ to 8‐year‐old prairie chronosequence and adjacent agricultural fields in southern Minnesota. We also established experimentally fertilized, watered, and control plots in the prairie chronosequence to examine the degree of nitrogen limitation on aboveground and belowground net primary production (ANPP and BNPP). Large shifts in functional diversity occurred within three growing seasons. First‐year prairies were dominated by annuals and biennials. By the second growing season, perennial native composites had become dominant, followed by a significant shift to warm‐season C4 grasses in prairies ≥3 yr old. Ecosystem properties that changed with the rise of C4 grasses included increased BNPP, litter mass, and C mineralization rates and decreased N mineralization rates. ANPP increased significantly with N fertilization but did not vary between young and old prairies with dramatically different plant community composition. Total soil C and N were not significantly different between prairie and agricultural soils in the depths examined (0–10, 10–20, 20–35, 35–50, 50–65 cm). We compared the results from our species‐rich prairie restoration to published data on ecosystem function in other restored grasslands, such as Conservation Reserve Program (CRP) and old‐field successional sites. Results suggest that rapid changes in functional diversity can have large impacts on ecosystem‐level properties, causing community‐ and system‐level dynamics in species‐rich prairie restorations to converge with those from low‐diversity managed grasslands.

Diversifying Agricultural Catchments by Incorporating Tallgrass Prairie Buffer Strips

“…This may be attributed to perennial species becoming established and, with time, having competitive advantages over annual species. Similar successional patterns were found in sown grassed margins around cropland throughout England (Critchley et al 2006) and in reconstructed tallgrass prairies in the USA (Schwartz and Whitson 1987, Rothrock and Squiers 2003, Camill et al 2004, which tended to shift from annual, weedy vegetation to perennial vegetation within four years of establishment. The plant community within the prairie buffer strips in our experiment followed the same successional trend as those within larger patches of reconstructed prairie reported in previous literature; therefore, buffer strips did not appear to be degraded by their proximity to conventionally managed crops.…”

“…The plant community within the prairie buffer strips in our experiment followed the same successional trend as those within larger patches of reconstructed prairie reported in previous literature; therefore, buffer strips did not appear to be degraded by their proximity to conventionally managed crops. If the prairie buffer strips continue to follow trends described in other investigations (Schwartz and Whitson 1987, Rothrock and Squiers 2003, Camill et al 2004), they will have more native and perennial prairie species in subsequent years.…”

Net energy of cellulosic ethanol from switchgrass

“…Low-input subsistence agriculture has low outputs, because essential factors needed to optimize capture of solar energy are lacking. The addition of nitrogen to undisturbed and restored high-diversity prairies has been shown to increase above-ground biomass production (31,32). These results demonstrate a similar situation likely exists for perennial biomass energy crops.…”

Physiological shifts in the microbial community drive changes in enzyme activity in a perennial agroecosystem

“…Perennial cropping systems, such as those proposed for cellulosic bioenergy production, may promote plant-microbial linkages because of their extensive root networks and allocation of belowground C. The development of perennial root systems during grassland restoration represents a significant source of C inputs to soils that stimulates microbial biomass and activity and can change community composition Bach et al 2010;Baer et al 2010;Barrett and Burke 2000;Camill et al 2004;McKinley et al 2005). Carbon additions from perennial root systems may also affect microbial communities in cultivated soils.…”

“…We predicted that changes in enzyme activity would be coupled to microbial biomass, and increase with increasing microbial biomass in the perennial agroecosystem. Furthermore, we predicted that microbial growth would result in concurrent increases in microbial respiration and N retention, as the utilization of C would increase microbial demand for N and reduce net N mineralization rates in the perennial system relative to the annual agroecosystem (Baer et al 2002Barrett and Burke 2000;Camill et al 2004). …”