@article {KNZ00961, title = {Vegetation-mediated changes in microclimate reduce soil respiration as woodlands expand into grasslands}, journal = {Ecology}, volume = {85}, year = {2004}, pages = {3348 -3361}, abstract = {This study compared annual and growing-season in situ soil respiration and soil C cycling in paired juniper woodland and C4-dominated grassland sites in eastern Kansas (USA) to determine if, under similar edaphic and regional climate conditions, vegetation change alters soil CO2 dynamics. We found marked differences in soil respiration related to vegetation: Growing season mean woodland soil respiration rates (4.6 μmoles{\textperiodcentered}m-2{\textperiodcentered}s-1) averaged 38\% less than paired grassland sites. Soil moisture did not explain the difference in soil respiration between woodlands and grasslands. Soil temperatures at the 10-cm depth were 5{\textdegree}C cooler in woodlands during the growing season and significantly different between woodlands and grasslands throughout the year, explaining most of the low soil respiration in woodlands. However, there were subtle intrinsic differences in the response of soil respiration to temperature between woodlands and grasslands: Woodland and grassland respiration response was significantly different at the P = 0.05 level, also indicated by a grassland Q10 of 2.4 compared to 2.2 in woodlands. We found no significant differences between woodlands and grasslands in long-term (82-week) laboratory incubations of potentially mineralizable soil C and short-term incubations for microbial biomass C. Similarly, root biomass did not differ between woodlands and grasslands and could not explain the lower in situ woodland soil respiration. Thus, vegetation-mediated reduction in soil temperature under the canopy explained much of the lower in situ woodland soil respiration. Lower soil respiration in the woodland resulted in an annual flux of 533.6 ({\textpm}21.7) compared to 858.4 ({\textpm}14.5) g C{\textperiodcentered}m-2{\textperiodcentered}yr-1 in grasslands, nearly 38\% lower in the woodland (means {\textpm} 1 se). Assuming root respiration is 50\% of soil respiration, we estimate that the turnover of woodland soil C stocks may be slowed by 15 years relative to grassland. This suggests that, if juniper expansion (now occurring across nearly 5 million hectares in the Great Plains) proceeds to canopy closure, annual soil C flux may be potentially reduced by as much as 19 {\texttimes} 106 Mg of C below C flux rates that occurred historically from tallgrass prairie soils.}, keywords = {LTER-KNZ}, doi = {10.1890/03-0576}, author = {Smith, D.L. and Johnson, L.C.} } @article {KNZ00851, title = {Expansion of Juniperus in the Great Plains: Changes in soil organic carbon dynamics}, journal = {Global Biogeochemical Cycles}, volume = {17}, year = {2003}, pages = {1062 -}, abstract = {[1] Woody encroachment by Juniperus virginiana into Great Plains grasslands allowed us to answer: Does changing the type of plant input to soils alter soil organic carbon (SOC) distribution or soil carbon (C) storage? The answer is critical because woody encroachment may alter C cycling over millions of hectares in the Great Plains and Midwest. We predicted that (1) forest SOC would become concentrated in shallow soil layers compared to SOC distribution in grassland, (2) woody expansion would increase soil C storage, and (3) forest C would be apparent in the larger soil organic matter fractions. Using δ13C signatures of SOC, 1/5 of the C from 0 to 25 cm in juniper forest soils was derived from C3 juniper trees. Forest C3 input occurred primarily in shallow surface layers: Forest soils developed over former C4 prairie contained 42\% C3-SOC from 0 to 2.5 cm depth, and decreased to 6\% at 25 cm. Isotopic analysis of SOC size fractions revealed that at 0{\textendash}2.5 cm, the forest soil fraction >212 μm was -25.7{\textperthousand}. The fraction <2 μm had a 13C isotope ratio of -17.0{\textperthousand} at the same depth, reflecting the predominance of residual prairie C in the smallest fraction. In spite of fast dynamics of soil C turnover, there was no net change in SOC amounts over 40{\textendash}60 years (cumulative mineral and organic SOC in forest, 8782 g C/m2 {\textpm} 810; in grassland, 7699 {\textpm} 1004). Thus as junipers expand into mesic areas of the Great Plains, juniper forests will provide little additional soil C storage.}, keywords = {LTER-KNZ}, doi = {10.1029/2002GB001990}, author = {Smith, D.L. and Johnson, L.C.} } @phdthesis {KNZ00855, title = {Changes in soil carbon dynamics during juniper expansion into tallgrass prairie}, volume = {PhD Dissertation}, year = {2001}, pages = {1 -137}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Smith, D.L.} } @article {KNZ00179, title = {Hydrologic and riparian influences on the import and storage of coarse particulate organic matter in a prairie stream}, journal = {Canadian Journal of Fisheries and Aquatic Science}, volume = {45}, year = {1988}, pages = {655 -665}, abstract = {

The hydrologic regime and zonation of riparian vegetation influenced the quantity and quality of coarse particulate organic matter (CPOM; greater than 1 mm) stored in the channel and upper bank of a prairie stream. In a 5.4 km intermittent reach of the South Branch of Kings Creek on Konza Prairie, Kansas, total annual import was lowest in headwater reaches and increased downstream. Total storage of benthic CPOM in the dry channel on the bank before the flow period was highest in the fourth- and fifth-order gallery forest zone (999 g ash-free dry mass.m-2) and less in upstream reaches (320-341 g.m-2). These longitudinal patterns of CPOM annual import and storage (before the flow period) were opposite those predicted by the river continuum concept for streams draining forested regions. Following flow, headwater channels had more CPOM (291 g.m-2) than downstream reaches. On the bank, storage was always highest in downstream reaches. Composition of CPOM both in the channel and on the bank varied with changes in riparian vegetation; grass tissues dominated in headwater channels, while wood and leaves of trees and shrubs were more abundant downstream. During the flow period, storage of CPOM increased only in headwater channels, where retention was high despite the lack of woody debris. In this intermittent prairie stream, benthic CPOM may not contribute consistently to the terrestrial/aquatic linkages that are suggested in the river continuum concept because of (1) a paucity of large CPOM sources (e.g. trees, shrubs) in the upper reaches and (2) a hydrologic regime that reduces the amount , as well as the predictability, of stored CPOM. The biota of prairie streams must have opportunistic food gathering and reproductive strategies to take advantage of variable food resources in a flow environment that is itself very unpredictable

}, keywords = {LTER-KNZ, gallery forest}, doi = {10.1139/f88-079}, author = {Gurtz, M.E. and Marzolf, G.R. and Killingbeck, K.T. and Smith, D.L. and McArthur, J.V.} } @article {KNZ00126, title = {Leaf litter processing and the associated invertebrate fauna in a tallgrass prairie stream}, journal = {The American Midland Naturalist}, volume = {116}, year = {1986}, pages = {78 -86}, abstract = {

Processing rates and invertebrate colonization of leaf material were measured from November 1980 through April 1981 in a tallgrass prairie stream. Processing rates of artificial leaf packs varied amongh specieis (hackberry\> elm\> chinquapin oak\> bur oak\> sycamore) and between sites (riffle\> pool). Sycamore and bur oak packs were colonized by more invertebrates (primarily collector-scrapers) than were hackberry, elm and chinquapin oak. Both leaf packs and samples of natural leaf aggregations from riffles contained more organisms (shredders in natural aggregations and collector-scrapers in the artificial leaf packs) than did leaf samples from the pools. Differences in invertebrate density between riffle and pool were greater for artificial leaf packs than for natural leaf aggregations. These differences may result from leaf pack construction as well as the natural distribution of leaf material within the stream. In Kings Creek, the slow processing rates, the relatively low densities and diversity of macroinvertebrates, as well as their types and distribution, suggest that 1) leaf material is used more as habitat than as a food source, and 2) macroinvertebrates are not likely to play a major role in degradation of leaf litter

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/2425939}, author = {Smith, D.L.} } @article {KNZ0033, title = {Chemical changes in tree leaves during decomposition in a tallgrass prairie stream}, journal = {Ecology}, volume = {63}, year = {1982}, pages = {585 -589}, abstract = {

As part of an investigation into the movement patterns of elements in a prairie watershed, we performed preliminary leaf pack experiments in which the concentrations of 10 elements were measured in undecomposed gallery forest litterfall, and in the same litterfall as it decomposed in the adjacent tallgrass prairie stream. What we report here are the patterns of concentration change in these 10 elements for three dominant gallery forest tree species during 16 weeks of in-stream decomposition

}, keywords = {LTER-KNZ, decomposition, leaf, prairie, stream, tallgrass}, doi = {10.2307/1938976}, author = {Killingbeck, K.T. and Smith, D.L. and Marzolf, G.R.} } @phdthesis {KNZ0036, title = {Macroinvertebrates and leaf litter decomposition in a tallgrass prairie stream}, volume = {PhD Dissertation}, year = {1982}, pages = {1 -60}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, decomposition, leaf, stream}, author = {Smith, D.L.} } @article {KNZ0030, title = {Organic matter loading and processing in a pristine stream draining a tallgrass prairie/riparian forest watershed}, journal = {Kansas Water Resources Research Institute Contribution No}, volume = {230}, year = {1982}, pages = {1 -78}, abstract = {

The means by which organic matter enters and leaves streams and the rates at which it does so are significant determinants of water quality. This report documents the import, storage, decomposition, and export of organic matter in a prairie stream from natural sources in a watershed on the Konza Prairie Research Natural Area that contains no human activity other than ecological research. This prairie stream has features that differ from streams in forested watersheds. During this one-year study, the headwater channels were ephemeral and drained watersheds vegetated by grasses rather than trees. They received less organic matter from the watershed but retained a larger fraction of it. Intermittent third and fourth order channels flowed through riparian gallery forest in the lower portions of the watershed and received more organic matter than headwater channels. They retained less of it during the period of flow (i.e., more was exported during storm flows) so in situ decomposition was reduced. These exports represent pulses of organic matter loading downstream

}, keywords = {LTER-KNZ, organic matter, prairie, stream, tallgrass}, author = {Gurtz, M.E. and Marzolf, G.R. and Killingbeck, K.T. and Smith, D.L. and McArthur, J.V.} }