Lloyd C. Hulbert

Woody plant invasion of unburned Kansas bluestem prairie.

Highlight: Postsettlement invasion of trees and shrubs on the bluestem prairie of Geary County in the Kansas Flint Hills was assessed using aerial photos, General Land Office survey data, and field observations. Tree cover increased 8% from 1856 to 1969 throughout the county, although on regularly burned sites combined tree and shrub cover was effectively maintained at presettlement amounts. On unburned sites, aerial photographs showed that combined tree and shrub cover increased 34% from 1937 to 1969; section-line data showed that tree cover alone increased 24% from 1856 to 1969. Data from two sites suggested that herbicide spraying only slowed the invasion rate. Woody plants increased only slightly on shallow, droughty clay loam soils located on level uplands, ridgetops, and upper slopes. On deeper and more permeable middleand lower-slope soils, woody plants increased more than 40% from 1937 to 1969. In 1937 trees covered 64% of the unburned, deep, permeable, lowland soils; by 1950 they had increased to 89%; change was slight thereafter. The increase in coverage of the lowland soils from 1856 to 1937 suggests that these soils are rapidly invaded. We conclude that on the Flint Hills bluestem prairie rangeland, (1) burning has been effective in restricting woody plants to natural, presettlemen t amounts and (2)-soil type and topography affect the rate of woody-plant invasion.

Causes of Fire Effects in Tallgrass Prairie

Eleven experimental treatments were applied to 2 x 2 m plots over 2 yr at Konza Prairie Research Natural Area, Riley County, Kansas, to ascertain why burning tallgrass prairie causes increased production and flowering. Warming of the soil in unburned plots resulted in an increase in both total production and flower stalk production of dom- inant tall grasses, primarily big bluestem (Andropogon gerardii) and Indian grass (Sor- ghastrum nutans), but the increase was small (34% increase in biomass; 78% increase in number of flower stalks) compared with that in burned plots (151 /% increase in biomass; 435% increase in flower stalks). Increased surface light intensity also appears to be a factor affecting changes in productivity following burning as suggested by the combined responses of increased productivity with removal of standing dead, whether by clipping or burning, and decreased productivity with shading. Further, the addition of ammonium nitrate in- creased yield 41 % and flowering 168% for the dominant grasses, suggesting that any factor increasing nitrogen availability would affect these vegetative parameters. Neither ash left from burning nor heating of the soil surface during burning produced detectable effects on subsequent vegetative growth. Different results for some parameters between years and between species suggest that many complex interactions operate to affect the grasslands response to burning, but surface light, soil surface temperature, and nitrogen appear to be particularly important factors.

Fire and Litter Effects in Undisturbed Bluestem Prairie in Kansas

Two— by two—meter plots of undisturbed, nearly pure Andropogon gerardi prairie were subjected to four treatments: burning, clipping and removal of the litter, burning the clipped litter and returning the ash, and the control (natural litter). Treatments were started in early April before growth began. Differences in results among the denuded plots were small and nonsignificant, but highly significant differences were found between denuded and control plots. Tiller number was increased 1.5 to 2.7 times by removal of litter. Growth began earlier in denuded than control plots. On May 31 yields were twice as great in denuded as in control plots. On September 1 ovendry yields were about 340 g/m2 in denuded and 180 in control plots. Soil temperatures were 1°/5°C higher in denuded than control plots the entire growing season, the differences lessening as the season progressed. Soil moisture was appreciably higher in control plots the entire season. The short—term effects of spring burning in undisturbed bluestem prairie with clay—loam soils are apparently related primarily to litter removal rather than to nutrient changes.

An Annotated List of the Vascular Flora of Konza Prairie Research Natural Area, Kansas

The Konza Prairie Research Natural Area is a 3487 hectare research area located in the northern Kansas Flint Hills. The vegetation of Konza Prairie is predominantly tallgrass prairie with limited gallery forests along major tributaries. The vascular flora of the research area includes 441 species in 90 families. This number represents approximately 44% of the species known to occur in the Kansas Flint Hills. Konza Prairie Research Natural Area (KPRNA) is located in the northern part of the Kansas Flint Hills. This 3487 ha (8616 acre) area is situated approximately 10 kilometers south of Kansas State University in Manhattan, Kansas. Most of the area is in extreme southcentral Riley County, the rest in adjacent Geary County. KPRNA is bounded on the east by Kansas Highway 177 and on the south by Interstate 70. Konza Prairie was acquired by The Nature Conservancy, a national nonprofit private organization dedicated to the preservation of lands exemplary of diversity in the natural world. The Geary County portion, called the original Konza Prairie, consists of 371 ha (917 acres) and was purchased in December 1971 (Fig. 1). In January of 1977, the 2921 ha (7219 acre) Dewey Ranch was added to the research area. A final acquisition was made by The Nature Conservancy in December 1977, when the 194 ha (480 acre) Thowe tract was added to KPRNA. The land is leased to Kansas State University for ecological research. Konza Prairie is one of eleven Long-Term Ecological Research (LTER) sites across the United States supported by the Division of Environmental Biology of the National Science Foundation. Konza Prairie is representative of the Flint Hills Upland, a band of rolling hills roughly 70 kilometers wide extending across Kansas from near the Nebraska-Kansas border south to Oklahoma. The hills were formed by the Contribution No. 83-74-j, Division of Biology, Kansas Agricultural Experiment Station, Manhattan. This content downloaded from 207.46.13.162 on Fri, 01 Jul 2016 04:08:27 UTC All use subject to http://about.jstor.org/terms VOLUME 88, NUMBERS 3-4 85 KONZA PRAIRIE RESEARCH NATURAL AREA 1 4e

PRODUCTION, DENSITY AND HEIGHT OF FLOWER STALKS OF THREE GRASSES IN ANNUALLY BURNED AND UNBURNED EASTERN KANSAS TALLGRASS PRAIRIE: A FOUR YEAR RECORD

response of height to fire was variable. In contrast, density and production of flower stalks were usually greater on the annually burned sites, whereas soil effects were inconsistent. Production of flower stalks for all three species combined ranged from 0 to 670 g/m2 during the 4-year period with maximum production occurring in a mesic year which followed a drought year. Various estimates of net primary production (aboveground biomass) have been used as ecological descriptors of grassland ecosystems throughout the world. Variations in aboveground productivity among grasslands in North America may range from 0 to 1000 g/m2/yr but within grassland types

FOREST SUCCESSION ON THE REPUBLICAN RIVER FLOODPLAIN IN CLAY COUNTY, KANSAS'

ment Station. This study supported by The Kansas Agricultural Experiment Station, also fulfilled a part of the requirement of the Ph.D. degree in plant ecology. ABSTRACT. On the Republican River floodplain in Clay County, Kansas, 39 forest stands were plot sampled in 1968. Salix interior (sandbar willow), S. amyg- daloides (almondleaf willow), and Populus deltoides (cottonwood) appeared the first or second year after alluvium was exposed above water level. Salix interior rarely persisted more than 10 years, S. amygdaloides not more than 30 years, and P. deltoides about a century. Young of these species did not survive in established stands. After about 100 years dominant trees included Ulmus americana (American elm), Celtis occidentalis (common hackberry), Fraxinus pensylvanica (green ash), Morus rubra (red mulberry), and Acer negundo (boxelder). No stand had attained climax, but Celtis occidentalis and Ulmus americana would likely have been dominants. Celtis may be the sole dominant in the future now that Dutch elm disease has en- tered the area. For young (0-10) and old (>60 years stands, mean tree density was 24,000/ha (9,710/acre) and 5,000/ha (2,020/acre), mean basal area was 20 m2/ha (87 ft2/ acre) and 39 m2/ha (170 ft2/acre) and mean basal area per tree > 6 cm diameter was 58 and 638 cm2, respectively. The amount of light that penetrated the forest capony ranged from 18% in young to 2% in old stands. Competition, especially ef- fects of shading, is thought to be more important than changes in soil in eliminating pioneer woody species. Polygonum lapathifolium, Ambrosia trifida and Conyza canadensis were the most common herbs in young stands. Galium aparine had a frequency of 20% in young stands and over 70% in stands more than 30 years old. Rhus radicans and Partheno- cissus quinquifolia were absent in young but common in old stands. Studies of floodplain forest succession provide knowledge that can be applied in managing timber, wildlife, recreation, and floods. Such forests in Kansas and nearby states have been little studied. In Kansas Schaffner (1906) referred briefly to river-bottom forests in Clay County; Smith (1940) to one 200-year old stand in the Smoky Hill Valley in Geary County; and Gesink, Tomanek and Hulett (1970)

An evaluation of beta attenuation for estimating aboveground biomass in a tallgrass prairie.

The attenuation of beta particles by vegetation was evaluated as a nondestructive method for estimating aboveground biomass in tallgrass prairie in northtast Kansas. Regression equations using the sum of beta attenuation measurements for each of 5 height classes within the vegetation and mean midday leafwater potential as the independent variables were ustd to predict live and total biomass. Live and total biomass were better predicted on burned (r2z.91 and .88, respeetivtly) than unburned sites (P=.71 and .70, respectively). Greater variability in the relationship between beta attenuation and biomass in unburned prairie was a result of the lPrgt and variable amount of dead biomass on unburned sites. Dead biomass was poorly predleted by beta attenuation (+.24 .49). Beta attenuation predicted biomass in burned tallgrass prairie within 315% of harvest values until late Season vegetative stntscenct. In unburned prairie, prtdictions were poorer, but the technique could still be ustful if the required accuracy need be only f25%. Measurement of aboveground biomass by clipping and weighing the vegetation is labor intensive and destroys the plot for subsequent measurements for at least a year. These disadvantages prompted t&e development of several nondestructive techniques [see Tucker (1980) for review]. Due to the success of Teare et al. (1966), Mitchell (1972), and Johnson et al. (1976) with the beta attenuation technique in herbaceous vegetation, we evaluated beta attenuation as a nondestructive method for estimating aboveground biomass in a tallgrass prairie. This evaluation was accomplished by deriving regression equations from calibration plots and testing their predictive value. Material and Methods Research was conducted on the Konza Prairie Research Natural Area (KPRNA) near Manhattan, Kans. The vegetation is characteristic of bluestem prairie (Bailey 1980). Sites burned annually (late April) or left unburned were used in this study. None of the sites have been grazed recently, nor had the unburned sites been burned for 5 years. The soil at the study sites is a moderately deep Reading silt loam (Typic Argiudolls; Jantz et al. 1975). The apparatus constructed to measure beta attenuation consisted of 4 parts: a beta particle source, a Geiger-Mueller (GM) tube, a scaler, and a mounting frame. The beta source consisted of 10 capsules (l-cm diameter) containing 10 microcuries of strontium% each. A side-window GM tube was placed 50 cm from the source. The GM tube was connected to a Ludlum model 2000 scaler to record the number of beta particles received by the GM tube. The beta source, GM tube, and scaler were mounted on a rigid frame with a moving section that held the GM tube at a fixed horizontal distance from the beta source, but permitted the tube and source to be moved vertically. Five vertical positions, repreAuthors are research associates and professor of plant ecology, Division of Biology, Kansas State Universitv, Manhattan 66506. and Department of Botany. University of Wyoming, Laramie, dY 8207 1. Research was suoaorted bv NSF arant DEB 80-12 166. R. Sherwood. G. Radke, R. Rogers, C. McAfe&*J. Bog&h, S. Peterson, D. Loring, R. Peak, R. Ramundo, and T. Seastedt provided valuable field assistance. E. Finck, E. Evans, and M. Gurtz assisted in data analysis. G.R. Marzolf and C.E. Owensby reviewed an earlier version of this manuscript and comments by W.K. Lauenroth wereappreciated. Raw data and supporting documentation are stored in the Konza Prairie Research Natural Area data bank (data set code = PBAOI). 556 senting 5 height classes were used in this study (O-lO, lO-20,20-30, 30-40, and 40-50 cm). This height stratification allowed the integration of the density of vegetation over the height of the stand (Teare et al. 1966). Further details on the construction and operation of the frame are available from L.C. Hulbert (Director, Konza Prairie Research Natural Area). Twenty 20XSO-cm plots, systematically located along 50-m transects, were sampled in burned and unburned tallgrass prairie at 2-week intervals from late-May to mid-September (1983). Four beta attenuation measurements were taken at S-cm intervals at each of the 5 heights in each plot (total q 20/plot). Vegetation in each plot was clipped at ground level, sorted into live and dead biomass, oven-dried, and weighed. After the 20 plots were clipped, additional beta attenuation measurements were made at 40 points along an adjacent transect. These data were used to test the accuracy of the predictive equation developed from the clipped plot data. Also, during the 1982 and 1983 growing seasons, a comparison of predicted biomass values with clipped plot data was made in nearby sites which had either shallower or deeper soils. Two to four times during a daily sampling period, 10 replications of beta attenuation were measured at each height class in an area devoid of vegetation. These measurements were used to correct vegetation measurements for daily and seasonal differences in absolute humidity and electronic drift. Attenuation was calculated using the following equation: T:T Beta Attenuation = I ~ Ti;‘i where T?< is the number of beta particles transmitted through the vegetation (in 6 sec.) at a given height (htS and Ti?c is the number of beta particles transmitted through the air. Leaf water potential (Yld) was measured concurrently with beta attenuation hourly on a clear day late in the 1982 growing season to determine if diurnal variations in the water relations of the vegetation influenced beta attenuation. Measurements of Yluf were made with a Scholandertype pressure chamber on 5-7 fully expanded leaves of big bluestern (Andropogon gerardii Vitman), the dominant species in the study area. Additionally, midday Y1-r (1500 hr CDT) was measured for 5-7 big bluestem leaves each week throughout the 1983 growing season to examine the relationship between seasonal variation in Y\~l*at nd beta attenuation. Regression equations were developed with total, live and dead biomass as the dependent variables and the sum of the beta attenuation measurements for each of the 5 height classes (Xatt) and the mean midday Yl,r preceding the sampling date (X Y1.d) as independent variables. Data transformations and model fitting followed the techniques described by Neter and Wasserman (1974). Results and Discussion The relationship between aboveground biomass and Watt was exponential as reported by Teare et al. (1966) and Mitchell (1972). Because of heteroscedasticity of variance in data sets from burned and unburned sites, a log/log transformation was necessary to meet the assumptions of a linear model (ln(x+ 1); Zar 1974). Several combinations of the height class variables were used but Catt produced the highest coefficient of determination. JOURNAL OF RANGE MANAGEMENT 38(6), November 1985 Two aspects of the relationship between the moisture content of the vegetation and beta attenuation were evaluated: diurnal and seasonal changes in leaf water potential. When the diurnal course of Yi,tand beta attenuation were monitored concurrently (Fig. 1)

Decomposition of Litter in Kansas Bluestem Prairie

From l April to 26 August 1978, about 45 percent of the aboveground standing dead plant material and litter disappeared in ungrazed bluestem prairie on Konza Prairie Research Natural Area, Geary County, Kansas, USA. In plots trampled on April l to compact the material close to the soil surface about 55 percent of the material decomposed. The results are based on 10 replications in native prairie on deep, productive, silty-clay loam at two sites, l and 5 years since burning. The amount of decomposition of aboveground standing dead plant material and litter was studied on the southern part of Konza Prairie Research Natural Area, 14 km south of Manhattan, Kansas at the north edge of Geary County. The study was begun in the spring of 1978 on two sites, one last burned in the spring of 1973, the other last burned in the spring of 1977, or 5 and l years since burning. Both were on lower slopes with Tully silty-clay loam, 4 to 8 percent slope. This soil is deep, not rocky, moderately permeable, and representative of the productive bluestem prairie soils that support grasses 2 meters tall in good years. The 108-year median precipitation at nearby Manhattan is 779 mm. In March, 1978, 50 plots, each 0.5 by 1.5 meters, were marked in a block in each of the two sites and two treatments were instituted: trampled and control. All plots were randomly selected. Ten plots in each site were sampled on April 1 to obtain the initial weight of above ground organic matter. At the same time the standing dead plant material was compacted on 20 plots at each site by breaking stems by hand and by walking on the plots until the material lay close to the soil surface. 1 Contribution No. 80-73-J, Division of Biology and Kansas Agricultural Experiment Station. This content downloaded from 157.55.39.78 on Sun, 19 Jun 2016 05:54:04 UTC All use subject to http://about.jstor.org/terms Table 1. Oven-dry weights (g/m2) and least signilicant differences (LSD) of standing dead plant material and litter at three dates on areas I year and 5 years since burning. Values in parentheses are percent loss in weight from the initial weights on I April. Averages of 10 plots, each 0.1 m2. I year since burning 5 years since burning Date of sampling Control Trampled Control Trampled I April 680 950 a* 5, 7 June 503 a (26) 382 ab (44) 884 a (7) 591 b (38) 26 August 383 ab (44) 334 b (51) 507 b (47) 332 (65) LSD, 59 102 LSD, 59 170 IC>o 136 1S, 228 * Values for each of the two treatments followed by the same letter are not significantly different at the 5 percent level. Sampling was done in 20 by 50 cm (0.1 m2) plots by clipping as close to the soil surface as feasible, placing the standing dead and litter in a paper sack, oven-drying at 60°C, and weighing. Production of the 1978 season was removed to the extent it could be distinguished. Separation was complete in June, but a small amount, probably insignificant to the current years growth, may not have been removed in August. Approximately 2 and 4 months after the first sampling, 10 control plots and 10 trampled plots were sampled in each site at each date. Vacuuming was not employed, but care was taken to pick up as much organic matter on the soil surface as possible in these small plots. A little less than half the aboveground dead organic matter disappeared in the four months from April through August (Table 1). Trampling caused a significant increase in the amount decomposed. The increase is likely to have resulted from slower drying and perhaps from warmer temperatures than in the untrampled material. The few other studies that provide information on rate of decomposition in bluestem or tallgrass prairie also found that about half of the material disappeared during the growing season (Hadley and Kieckhefer, 1973; Kucera et al., 1967). The increased rate of decomposition resulting from trampling implies that compaction by snow speeds up decomposition. This should help compensate for the shorter decomposition season in the northern than in the southern part of the bluestem prairieX and is a factor in the variation in amount of aboveground dead organic matter from year to year. The trampling effect also implies that trampling by livestock would increase decomposition, but this effect would be complicated by changes in the amount of material entering the standing dead plant material and litter 34 compartments of the ecosystem (Sims and Singh, 1978). TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCES This content downloaded from 157.55.39.78 on Sun, 19 Jun 2016 05:54:04 UTC All use subject to http://about.jstor.org/terms VOLUME 83, NUMBER 1 35