02489nas a2200157   4500008004100000245009000041210006900131300001300200490000700213520191500220653002202135100002402157700001602181700001902197856011502216       2002                        eng d00aEffect of local and regional processes on plant species richness in tallgrass prairie0 aEffect of local and regional processes on plant species richness  a571 -5790 v993 aHistorically, diversity in a community was often believed to result primarily from local processes, but recent evidence suggests that regional diversity may strongly influence local diversity as well. We used experimental and observational vegetation data from Konza Prairie, Kansas, USA, to determine if: (1) there is a relationship between local and regional richness in tallgrass prairie vegetation; (2) local dominance reduces local species richness; and (3) reducing local dominance increases local and regional species richness. We found a positive relationship between regional and local richness; however, this relationship varied with grazing, topography and fire frequency. The decline in variance explained in the grazed vegetation, in particular, suggested that local processes associated with grazing pressure on the dominant grasses strongly influenced local species richness. Experimental removal of one of the dominant grasses, Andropogon scoparius, from replicate plots resulted in a significant increase in local species richness compared to adjacent reference plots. Overall all sites, species richness was higher in grazed (192 spp.) compared to ungrazed (158 spp.) areas. Across the Konza Prairie landscape, however, there were no significant differences in the frequency distribution of species occurrences, or in the relationship between the number of sites occupied and average abundance in grazed compared to ungrazed areas. Thus, local processes strongly influenced local richness in this tallgrass prairie, but local processes did not produce different landscape-scale patterns in species distribution and abundance. Because richness was enhanced at all spatial scales by reducing the abundance of dominant species, we suggest that species richness in tallgrass prairie results from feedbacks between, and interactions among, processes operating at multiple scales in space and time.10atallgrass prairie1 aCollins, Scott., L.1 aGlenn, S.M.1 aBriggs, J., M.  uhttp://lter.konza.ksu.edu/content/effect-local-and-regional-processes-plant-species-richness-tallgrass-prairie04798nas a2200133   4500008004100000245009700041210006900138300001300207490000600220520427600226100002404502700001604526856012204542       1997                        eng d00aEffects of organismal and distance scaling on analysis of species distribution and abundance0 aEffects of organismal and distance scaling on analysis of specie  a543 -5510 v73 aAs communities and populations become increasingly fragmented, much theoretical and some empirical research has focused on the dynamics of metapopulations. Many metapopulation models describe dynamics among populations in a region, yet the scale of the region to which different models apply often is undefined. Because the spatial scale is undefined, testing predictions and assumptions of these models is problematic. Our goal is to present two scaling concepts relevant to these models, distance scaling and organismal scaling, and to apply these scaling notions to patterns of species distribution. To determine distance effects, we analyzed patterns of distribution of four taxonomic groups in tallgrass prairie (grasshoppers, small mammals, vascular plants, and breeding birds) at two spatial scales. To asses organismal effects, we held spatial scale constant and we compared patterns of distribution and abundance among these taxonomic groups. Using long—term data from Konza Prairie, Kansas, there were significant differences in the pattern of distribution of grasshoppers, small mammals, vascular plants, and breeding birds within a single spatial scale. The number of core species (species occupying >90% of the sites in a region) of plants and birds was less than the number of satellite species (those occupying <10% of the sites in a region). The opposite was true for grasshoppers and small mammals. All four distribution patterns were significantly nonrandom, but only grasshoppers and small mammals were significantly bimodal at this scale. Plants and birds were unimodal. The patterns of distribution within these taxonomic groups at two spatial scales were significantly different as well. In all cases, the percentage of species in the core group declined, and the percentage of species in the satellite group increased as spatial scale increased. These results demonstrate the difficulty of testing theoretical models with only one taxonomic group at a single spatial scale. One should not accept or reject a model until the spatial domains of organismal and distance scaling have been properly evaluated.

As communities and populations become increasingly fragmented, much theoretical and some empirical research has focused on the dynamics of metapopulations. Many metapopulation models describe dynamics among populations in a region, yet the scale of the “region” to which different models apply often is undefined. Because the spatial scale is undefined, testing predictions and assumptions of these models is problematic. Our goal is to present two scaling concepts relevant to these models, distance scaling and organismal scaling, and to apply these scaling notions to patterns of species distribution. To determine distance effects, we analyzed patterns of distribution of four taxonomic groups in tallgrass prairie (grasshoppers, small mammals, vascular plants, and breeding birds) at two spatial scales. To assess organismal effects, we held spatial scale constant and we compared patterns of distribution and abundance among these taxonomic groups.

Using long-term data from Konza Prairie, Kansas, there were significant differences in the pattern of distribution of grasshoppers, small mammals, vascular plants, and breeding birds within a single spatial scale. The number of core species (species occupying >90% of the sites in a region) of plants and birds was less than the number of satellite species (those occupying <10% of the sites in a region). The opposite was true for grasshoppers and small mammals. All four distribution patterns were significantly non-random, but only grasshoppers and small mammals were significantly bimodal at this scale. Plants and birds were unimodal. The patterns of distribution within these taxonomic groups at two spatial scales were significantly different as well. In all cases, the percentage of species in the core group declined, and the percentage of species in the satellite group increased as spatial scale increased. These results demonstrate the difficulty of testing theoretical models with only one taxonomic group at a single spatial scale. One should not accept or reject a model until the spatial domains of organismal and distance scaling have been properly evaluated.1 aCollins, Scott., L.1 aGlenn, S.M.  uhttp://lter.konza.ksu.edu/content/effects-organismal-and-distance-scaling-analysis-species-distribution-and-abundance01376nas a2200133   4500008004100000245008800041210006900129300001300198490000700211520094300218100002401161700001601185856004101201       1997                        eng d00aIntermediate disturbance and its relationship to within-and between-patch structure0 aIntermediate disturbance and its relationship to withinand betwe  a103 -1100 v213 aThe intermediate disturbance hypothesis has been the focus of considerable analysis in terrestrial and aquatic systems. This model predicts that species diversity will be highest at intermediate frequencies of disturbance. Despite numerous theoretical and empirical analyses, the utility of the model is still the subject of intense debate. Rather than developing restrictive time and space constraints on application, we suggest that the model may best be used as a generalizable framework for testing hypotheses in both aquatic and terrestrial systems. In addition, we believe that the model may be applied to both within- and between-patch scales. Finally, we propose an empirical model in which disturbance is an extinction causing event, and post-disturbance succession is modeled based on the dynamics of immigration and extinction. Such a model can incorporate a variety of patterns in species diversity in response to disturbance.1 aCollins, Scott., L.1 aGlenn, S.M.  uhttp://www.jstor.org/stable/2405453002545nas a2200145   4500008004100000245011700041210006900158300001300227490000700240520196500247100002402212700001602236700001702252856013002269       1995                        eng d00aExperimental analysis of intermediate disturbance and initial floristic composition: decoupling cause and effect0 aExperimental analysis of intermediate disturbance and initial fl  a486 -4920 v763 aThe intermediate disturbance hypothesis predicts that richness will be highest in communities with moderate levels of disturbance and at intermediate time spans following disturbance. This model was proposed as a nonequilibrium explanation of species richness in tropical forests and coral reefs. A second model of succession, initial floristic composition, states that nearly all species, including late seral species, are present at the start of succession. This leads to the prediction that richness should be highest immediately following disturbance. We tested these predictions using plant species composition data from two long—term field experiments in North American tallgrass prairie vegetation. In contrast to one prediction of the intermediate disturbance hypothesis, there was a significant monotonic decline in species richness with increasing disturbance frequency, with no evidence of an optimum, in both field experiments. Species composition on an annually burned site was a subset of that of infrequently burned sites. The average number of species per quadrat and the number of grass, forb, and annual species were lowest on annually burned sites compared to unburned sites and sites burned once every 4 yr. The second prediction of the intermediate disturbance hypothesis, however, was supported. Richness reached a maximum at an intermediate time interval since the last disturbance. This contradicts the prediction from the initial floristic composition model of succession. These results also suggest that the two predictions of the intermediate disturbance hypothesis are independent and unrelated. We propose that this may be explained by uncoupling the effects of disturbance as a single, relatively discrete event from system response to disturbance. From this perspective, disturbance becomes an extinction—causing event in these grasslands, where recovery following disturbance is a balance between immigration and extinction.1 aCollins, Scott., L.1 aGlenn, S.M.1 aGibson, D.J.  uhttp://lter.konza.ksu.edu/content/experimental-analysis-intermediate-disturbance-and-initial-floristic-composition-decoupling02898nas a2200241   4500008004100000245009700041210006900138300001300207490000700220520209400227653001402321653002202335653002402357653002302381653001802404653001202422653002502434100001502459700002402474700001602498700001602514856012602530       1995                        eng d00aFine-scale spatial organization of tallgrass prairie vegetation along a topographic gradient0 aFinescale spatial organization of tallgrass prairie vegetation a  a169 -1840 v303 aFine-scale spatial patterns of native tallgrass prairie vegetation were studied on Konza Prairie, Kansas, USA. Three sites, upland, slope, and lowland, were sampled in an ungrazed watershed. Presence of vascular plant species was recorded in two 25.6 m long transects of contiguous 5×5 cm micro-quadrats on each topographic position. Spatial patterns of species and functional groups were analyzed by information theory models ofJuhász-Nagy. Within-community variability of coexistence was expressed by the diversity and spatial dependence of local species combinations. Considerable diversity in the local coexistence of species was found on each site. Upland and hillside communities were richer and more diverse in species combinations than lowland. Spatial scale effected coexistence relationships. The maxima of information theory estimates varied between 15 and 30 cm. There was no trend in the variation of characteristic scales along the topographical gradient. Above 10 m, all sites tended to be homogeneous.
The analysis of spatial associations revealed that variability in the local coexistence of species was strongly constrained in all topographic positions. Overall spatial association of species was the lowest on lowland. The characteristic scales of maximum association were between 1.2 m and 3 m at all sites. The maxima of information theory estimates for the functional group-based data appeared at smaller plot sizes than for the species based analyses. Only weak spatial associations were detected among the functional groups indicating that individuals of functional groups coexist well at small scales, and form combinations close to random expectations. The length of transects did not effect the relative associations. Strong positive correlations were found between the number of components (species or functional groups) and the maxima, of information theory models suggesting that richness is a good predictor of within-community coexistence relations. However, there was no relationship between richness and the characteristic scales of community patterns.10adiversity10aFunctional groups10aGrassland community10ainformation theory10aKonza Prairie10aScaling10aSpatial associations1 aBartha, S.1 aCollins, Scott., L.1 aGlenn, S.M.1 aKertesz, M.  uhttp://lter.konza.ksu.edu/content/fine-scale-spatial-organization-tallgrass-prairie-vegetation-along-topographic-gradient00479nas a2200145   4500008004100000245004700041210004700088260002800135300001300163100002400176700001600200700001900216700001700235856008100252       1995                        eng d00aGrassland ecosystem and landscape dynamics0 aGrassland ecosystem and landscape dynamics  bOxford University Press  a128 -1561 aCollins, Scott., L.1 aGlenn, S.M.1 aJoern, Anthony1 aKeeler, K.K.  uhttp://lter.konza.ksu.edu/content/grassland-ecosystem-and-landscape-dynamics02504nas a2200181   4500008004100000245008300041210006900124300001300193490000600206520186400212653002402076653002002100653002302120653002802143100001602171700002402187856011102211       1993                        eng d00aExperimental analysis of patch dynamics in tallgrass prairie plant communities0 aExperimental analysis of patch dynamics in tallgrass prairie pla  a157 -1620 v43 aPrevious research has indicated that patch structure at small spatial scales (<100m2) in tallgrass prairies was defined by a diverse array of infrequent species because dominant species occurred in all samples at this scale. Also, patch structure was not significantly different from that derived from random species associations. Based on these results, we hypothesized that remo val of a dominant species would have no effect on patch structure in these prairies. We tested this hypothesis by removing a dominant grass, Schizachyrium scoparium (Poaceae), from half of each of four 10 m × 10 m study blocks, and comparing differences in patch structure between control and removal halves before and after removal. The minimum resolution in our study was 1 m2. Patches of similar species composition were defined by cluster analysis of presence/absence data and cover data. Patch sizes ranged from 1 to 34 m2.

Following the removal of S. scoparium there was an overall increase in the number of species in the removal half of each block compared to pre-treatment levels. However, the number of patch types and number of spatially mapped groups, based on presence/absence or cover data, did not change between control and removal plots after the removal of S. scoparium. This supports the hypothesis that removal of a large, dominant species would have no effect on patch structure at this scale of resolution in these prairies. Thus, patch structure, as defined here, is an emergent property in these grasslands that is not predictable from changes in species composition. This property of stochastic patch structure results from interactions of processes operating at scales both larger and smaller than our scale of resolution. Stochastic models may provide a reasonable approach to modelling small-scale patch dynamics in tallgrass prairie communities.10aGrassland community10aPatch structure10aRemoval experiment10aSchizachyrium scoparium1 aGlenn, S.M.1 aCollins, Scott., L.  uhttp://lter.konza.ksu.edu/content/experimental-analysis-patch-dynamics-tallgrass-prairie-plant-communities02278nas a2200193   4500008004100000245003900041210003500080300001300115490000600128520173000134653002401864653002001888653002201908653002701930100002401957700001601981700001801997856006902015       1993                        eng d00aThe hierarchical continuum concept0 ahierarchical continuum concept  a149 -1560 v43 aTwo general models have been proposed to explain the structure of the plant community: the community-unit model of Clements and the continuum model of Whittaker and Curtis, the latter based on Gleason's individualistic distribution of species. It is generally assumed that most ecologists now accept the continuum model. Empirical evidence suggests, however, that the continuum in its current form does not fully describe the observed patterns of vegetation along environmental gradients. In this paper, we introduce the hierarchical continuum as a general concept to represent dynamic community structure along regional spatial gradients. The hierarchical continuum is derived from a combination of the individualistic distribution of species, hierarchical assemblage structure, and the core-satellite species hypothesis. The hierarchical continuum concept predicts that the distribution of species across sites in a region will be polymodal, which reflects hierarchical structure, and that the distribution and abundance of species within and between sites will be spatially and temporally dynamic. Regional distribution of plant species in North American tallgrass prairie, southeastern flood-plain hardwood forests, northern upland hardwood forests, and boreal forests were either bimodal or polymodal as predicted by the hierarchical continuum concept. Species in tallgrass prairie were spatially and temporally dynamic with an average turnover of 8–9 species per 50 m2 yr1. In addition, the hierarchical continuum concept predicts the potential for fractal (self-similar) patterns of community structure, and provides a framework for testable hypotheses concerning species distributions along environmental gradients.10acommunity structure10aContinuum model10aGradient analysis10aHierarchical structure1 aCollins, Scott., L.1 aGlenn, S.M.1 aRoberts, D.W.  uhttp://lter.konza.ksu.edu/content/hierarchical-continuum-concept00573nas a2200145   4500008004100000245009600041210006900137300001300206490000600219653002200225100001600247700002400263700001700287856012300304       1992                        eng d00aDisturbances in tallgrass prairie: local versus regional effects on community heterogeneity0 aDisturbances in tallgrass prairie local versus regional effects   a243 -2520 v710atallgrass prairie1 aGlenn, S.M.1 aCollins, Scott., L.1 aGibson, D.J.  uhttp://lter.konza.ksu.edu/content/disturbances-tallgrass-prairie-local-versus-regional-effects-community-heterogeneity02075nas a2200145   4500008004100000245009900041210006900140300001300209490000700222520153300229653000901762100001601771700002401787856011801811       1992                        eng d00aEffects of scale and disturbance on rates of immigration and extinction of species in prairies0 aEffects of scale and disturbance on rates of immigration and ext  a273 -2800 v633 a<p>Relationships between local annual immigration and extinction rate of plant species and total species richness were determined from long-term data in permanent plots in tallgrass and shortgrass prairies in Kansas. Combining plots resulted in higher equilibrium numbers of species as predicted from immigration and extinction rates. Immigration and extinction rates also increased with scale. Extinction rates are higher because the regional scale supports more rare species which, in turn, have high probabilities of extinction. We also tested the hypothesis that extinction rates would be higher on burned versus unburned grasslands, and that immigration rates would be higher on grazed versus ungrazed grasslands. Extinction rates were positively correlated with the number of species at a site, and this relationship was not altered by burning or grazing. Immigration rates were variable, but were sometimes positively correlated with growing season precipitation. Immigration rates decreased in years sites were burned. Therefore, after fire, the number of species going locally extinct was still dependent on earlier species richness, but the number of species added to the site was reduced. Variances in immigration and extinction rates were high, therefore, confident predictions regarding the effects of burning or grazing regimes on species richness could not be made. Variance in rates of immigration and extinction results in a range of values within which the equilibrium number of species fluctuates randomly</p>10afire1 aGlenn, S.M.1 aCollins, Scott., L.  uhttp://lter.konza.ksu.edu/content/effects-scale-and-disturbance-rates-immigration-and-extinction-species-prairies00510nas a2200121   4500008004100000245009500041210006900136300001300205490000700218100002400225700001600249856012300265       1991                        eng d00aImportance of spatial and temporal dynamics in species regional abundance and distribution0 aImportance of spatial and temporal dynamics in species regional   a654 -6640 v721 aCollins, Scott., L.1 aGlenn, S.M.  uhttp://lter.konza.ksu.edu/content/importance-spatial-and-temporal-dynamics-species-regional-abundance-and-distribution00483nas a2200121   4500008004100000245008200041210006900123300001300192490000800205100002400213700001600237856010800253       1990                        eng d00aA hierarchical analysis of species abundance patterns in grassland vegetation0 ahierarchical analysis of species abundance patterns in grassland  a633 -6480 v1351 aCollins, Scott., L.1 aGlenn, S.M.  uhttp://lter.konza.ksu.edu/content/hierarchical-analysis-species-abundance-patterns-grassland-vegetation02163nas a2200145   4500008004100000245007300041210006900114300001300183490000700196520165200203653002201855100001601877700002401893856010001917       1990                        eng d00aPatch structure in tallgrass prairies: dynamics of satellite species0 aPatch structure in tallgrass prairies dynamics of satellite spec  a229 -2360 v573 a<p>Space in tallgrass prairie communities is dominated by a few core species. A large number of less abundant, satellite species occupy the remaining space. These satellite species define vegetation patches that vary withinn and between growing seasons. In order to determine if patch structure was random we established five permanent 100-m2 blocks in undisturbed tallgrass prairie in Oklahoma and Kansas. Presence of core and satellite species in each m2 was sampled over one or two growing seasons. Patch types were defined by cluster analysis. Characteristics of patch structure included number of patch types, patch type diversity, patch composition, number of spatial groups, group size, and fractal dimension of the spatial groups. We generated simulated data sets with random species associations, in which we quantified patch structure. Actual patch structure, defined mainly by satellite species, was not significanly different from simulated patch structure, except that simulated patches were more fragmented. Therefore, processes that affect species associations may not be important controls of patch structure of satellite species within the spatial and temporal scale of this analysis. Because there was some degree of spatial autocorrelation in patch structure, dispersal processes may have significant effects on patch structure at this scale. In order to understand grassland community dynamics, we propose that satellite species should be modelled using stochastic models constrained by core species dynamics. This approach may be applicable to any community with major components operating at different hierarchical levels</p>10atallgrass prairie1 aGlenn, S.M.1 aCollins, Scott., L.  uhttp://lter.konza.ksu.edu/content/patch-structure-tallgrass-prairies-dynamics-satellite-species