Relict Stands Research Articles

Справочная информационная система FLR-Library для адаптивного лесовосстановления: информационная модель

The process of restoring forest landscapes in the context of global urbanization and deforestation of relict stands,
 as well as climate change, is complex and important for studying, planning stages and technological operations and
 predicting the results of vitality and growth of stands. To solve this problem, a reference information system for adaptive
 reforestation is being developed. In this paper, the modeling and description of the adaptive reforestation process is carried
 out using functional diagrams constructed using the IDEF0 methodology, and the description of the arrows of the context
 diagram with explanations of the processes is given in detail. For a detailed analysis of the subject area and modeling of
 the adaptive reforestation process, we decomposed the context diagram into diagram A1, which shows the implementation
 of the process of choosing a technology for the restoration of the forest landscape from the point of view of technology
 and technical means, and diagram A2, which examines the restoration technology from the point of view of several
 forestry descriptors, which takes into account the specifics of the industry. As a result of the simulation, diagrams A0,
 A1, A2 were obtained, which show a structured image of the system functions, information and objects connecting these
 functions.

Relict stands of Central European oaks: Unravelling autochthony and genetic structure based on a multi-population study

Central European white oaks expanded rapidly after the last glacial period and reached their current distribution range during the early Holocene. They have been an important resource of timber, fuelwood and animal feed for humans, who actively promoted their presence in forests and other landscape types at least since the early historical times. Besides stands with intensive management, putatively relict populations of three native oak species can be found on unproductive sites with restricted accessibility. Here, we apply chloroplast and nuclear microsatellite markers in order to address the autochthony of relict and managed stands and compare the spatial distribution of genetic variation between them. Based on data from more than 150 populations, we demonstrate that oak autochthony was preserved throughout historical times which is likely the result of traditional silvicultural treatment. This is supported by the fact that the spatial pattern of chloroplast haplotype distribution still reflects the post-glacial recolonization in both relict and old managed stands. We observed significant admixture of haplotypes only in stands established after the Second World War, which is attributable to the transfer of reproductive material used for afforestation. In terms of nuclear genetic variation, we observed marked differences among species. Quercus pubescens exhibited a pronounced genetic structure. Genetic drift and limited gene flow among its small and isolated populations in our study area might have contributed to this pattern. Varying extent of genetic introgression with other sympatric oak species could offer an additional explanation. On the contrary, the gene pools of Q. petraea and Q. robur are highly homogenous, displaying only weak isolation-by-distance. We found no significant differences of genetic diversity and differentiation between relict and managed stands. This suggests that seed transfer mostly occurred within our study area, even in those stands established in post-war times, verifying previous findings which point out limited human interference. We recommend consideration of population genetic structure for gene conservation, with a finer resolution of gene conservation units needed for Q. pubescens due to its spatial genetic structure. Both relict and old managed stands, species-pure or mixed, are suitable for conservation, as they host autochthonous gene pools. Coppice-with-standard management could contribute to preservation of autochthony. In the face of climate change, it is also important to maintain the evolutionary potential of the stands, by facilitating generative reproduction and allowing for hybridization in mixed stands.

The effects of fire on Pinus sylvestris L. as determined by dendroecological analysis (Sierra de Gredos, Spain)

Iberian populations of Scots pine (Pinus sylvestris L.) have been declining since the late-glacial period; among those that remain, relict stands have great biological and ecological value. This paper investigates the effects of a 2009 fire on tree growth in one of these small populations in the Sierra de Gredos (Spain) by examining the responses recorded in the tree-ring width series of the surviving trees. The current status and distribution of these surviving trees reveal the severity of the fire; indeed most show scars or other evidence of fire damage. Dendroecological analysis revealed narrower tree rings, indicating negative pointer years for the year of the fire and the following year. A very significant reduction in growth was recorded for the years after the fire, both in terms of tree-ring width and basal area increment; incomplete and even absent rings were also recorded. No relationship was seen between these effects and climatic events. The dates and geographical extension of former possible disturbances were also investigated, using the data from these same trees plus information collected from others in the region. The vulnerability of these populations to past fires was evident. Lastly, given the problems affecting the regeneration of these relict populations, it is strongly suggested to urgently include all these populations in conservation and environmental management programs.

20,000 years of interactions between climate, vegetation and land use in Northern Greece

Detailed knowledge about the history of vegetation, fire and land use is scarce in Northern Greece. We analysed lake sediments from Limni Zazari (Northern Greece) to reconstruct the past local vegetation and fire history with a special focus on land use and its impacts on erosion and lake eutrophication. Our data suggest a rather dense steppic vegetation after ca 20,000 cal bp (18050 cal bc). Forest expansion with Pinus sylvestris and admixed Quercus pubescens started around 14,500 cal bp (12550 cal bc). After the onset of the Holocene, mixed deciduous sub-mediterranean oak forests expanded, accompanied by rapidly decreasing soil erosion rates and increasing aquatic biological productivity. Pollen of cereals and Plantago lanceolata suggests continuous farming activities in the region after 8,200 cal bp (6250 cal bc), in agreement with archaeological evidence. Fairly closed mixed pine-oak forests dominated the landscape until ca 3,500 cal bp (1550 cal bc) that were only temporarily reduced during the Neolithic around 7,100 and 6,500 cal bp (5150 and 4550 cal bc). Land cover changes and aquatic biogeochemistry were closely linked during this period. Forest phases corresponded to lake eutrophication and hypolimnetic anoxia (meromixis), whereas during periods of deforestation (e.g. around 8,200 cal bp/6250 cal bc) soil erosion rates and lake mixing increased, while aquatic productivity decreased. After 3,500 cal bp (1550 cal bc) humans disrupted forests and open land vegetation expanded (e.g. Artemisia, Rumex-type, Cichorioideae, Chenopodiaceae). With the onset of the Iron Age (ca. 3,050 cal bp/1100 cal bc) grassland communities expanded massively and pine-oak forests gradually declined. Anthropogenic pressure on forests increased even more during the past 500 years. Finally, forest recovery during the recent decades led to decreased erosion and increased lake productivity. We conclude that over the millennia, intense pastoral and arable activities shaped both aquatic and terrestrial environments, ultimately creating a humanized vegetation mosaic in which the original natural mixed deciduous oak forests only form relict stands. Future climate warming and decreasing anthropogenic pressure may release a rapid spread of mixed deciduous oak forests around Limni Zazari.

Estimating exotic gene flow into native pine stands: zygotic vs. gametic components.

Monitoring contemporary gene flow from widespread exotic plantations is becoming an important problem in forest conservation genetics. In plants, where both seed and pollen disperse, three components of exotic gene flow with potentially unequal consequences should be, but have not been, explicitly distinguished: zygotic, male gametic and female gametic. Building on a previous model for estimating contemporary rates of zygotic and male gametic gene flow among plant populations, we present here an approach that additionally estimates the third (female gametic) gene flow component, based on a combination of uni- and biparentally inherited markers. Using this method and a combined set of chloroplast and nuclear microsatellites, we estimate gene flow rates from exotic plantations into two Iberian relict stands of maritime pine (Pinus pinaster) and Scots pine (Pinus sylvestris). Results show neither zygotic nor female gametic gene flow but moderate (6-8%) male gametic introgression for both species, implying significant dispersal of pollen, but not of seeds, from exotic plantations into native stands shortly after introduced trees reached reproductive maturity. Numerical simulation results suggest that the model yields reasonably accurate estimates for our empirical data sets, especially for larger samples. We discuss conservation management implications of observed levels of exposure to nonlocal genes and identify research needs to determine potentially associated hazards. Our approach should be useful for plant ecologists and ecosystem managers interested in the vectors of contemporary genetic connectivity among discrete plant populations.

Tidal Marsh Vegetation of China Camp, San Pablo Bay, California

China Camp (Marin County, California) preserves extensive relict stands of salt marsh vegetation developed on a prehistoric salt marsh platform with a complex sinuous tidal creek network. The low salt marsh along tidal creeks supports extensive native stands of Pacific cordgrass (Spartina foliosa). The outer salt marsh accreted following hydraulic gold mining sedimentation. It consists of a wave-scarped pickleweed-dominated (Sarcocornia pacifica) high salt marsh terrace with a broad fringing low marsh dominated by S. foliosa, including intermittent, variable stands of alkali-bulrush (Bolboschoenus maritimus). Most of the extensive prehistoric salt marsh plains within the tidal creek network also support mixed assemblages of S. pacifica, but high marsh zones along tidal creek banks support nearly continuous linear stands of gumplant (Grindelia stricta) and saltgrass (Distichlis spicata) with more diverse salt marsh forb assemblages. Salt pans with submerged wigeongrass (Ruppia maritima) are scarce, local, and small. The landward edge of the tidal marsh forms rare examples of ecotones with adjacent terrestrial vegetation, including those of alluvial valleys (riparian scrub and woodland, freshwater marsh, sedge-rush meadows) and hillslope grassland and oak woodland vegetation. Narrow high tidal marsh ecotones bordering terrestrial grasslands are locally dominated by creeping wildrye (Elymus triticoides) and Baltic rush (Juncus balticus), mostly on south-facing slopes. Brackish tidal marsh ecotones above ordinary high tides are associated with freshwater discharges from groundwater and surface flows. Brackish marsh ecotones support large clonal stands of sedge, bulrush, and rush vegetation (Carex praegracilis, C. barbarae, Bolboschoenus maritimus, Juncus phaeocephalus, Schoenoplectus acutus), intergrading with terrestrial freshwater wetlands and salt marsh. The terrestrial ecotone assemblages at China Camp are comparable with those of other prehistoric tidal marshes in the San Francisco Estuary, but China Camp lacks most native clonal perennial Asteraceae and halophytic annual forbs of the region’s remnant high tidal marsh ecotones. Few globally rare salt marsh plant populations have been reported from China Camp within the National Estuarine Research Reserve and State Park boundaries, but some species regionally uncommon in San Francisco Bay tidal marshes occur. To date, non-native tidal marsh plant invasions have been relatively minor and localized within China Camp.

Survival and relative frequency of native woody species and their specialist Lepidoptera on Coll, Inner Hebrides, two millennia after deforestation

AbstractThe Hebridean island of Coll has almost certainly been predominantly treeless for at least two millennia; it was certainly largely deforested when the first surviving written description of the island was made in the sixteenth century. A survey of the surviving native trees, shrubs and lianes carried out between 1997 and 2011 showed that only Salix aurita is present in any quantity, with all other species being reduced to small, relict stands or scattered individuals. Juniperus communis (at least 650 bushes), Populus tremula (450 trees) and Sorbus aucuparia (121 trees) are the commonest of these species and represent contrasting strategies, with P. tremula present as long-lived suckering clones and the others as freely seeding but probably short-lived individuals. Betula pubescens (42 trees), Hedera helix (50 plants), Corylus avellana (17 trees), Quercus spp. (11 trees) and Salix cinerea (4 stands) are the rarest surviving native species. Historical records indicate a decline since the 1930s of Be...

Competition modulates the adaptation capacity of forests to climatic stress: insights from recent growth decline and death in relict stands of the Mediterranean fir Abies pinsapo

Summary 1. Long‐term basal area increment (BAI) in Abies pinsapo was studied to investigate the way density‐dependent factors modulate the responses of radial growth to climatic stresses in relict stands of a drought‐sensitive Mediterranean fir. 2. First, we verified that spatially explicit competition predicts mean A. pinsapo BAI at our study site; i.e. it modulates the degree to which the average climate‐driven potential for growth is expressed. Second, we verified that the long‐term pattern of temperature predicts the long‐term pattern of BAI, estimated as the main trend over a time period of c. 40 years. Finally, we assessed whether the intensity of tree‐to‐tree competition restrains the potential improvements achieved by our model of BAI when a short‐term, high‐frequency stressor such as drought (inter‐annual precipitation variability) is introduced. 3. We applied Dynamic Factor Analysis (DFA) to characterize regional climatic trends and to test the hypothesis that trees subjected to contrasting competition intensity may differ in their growth pattern. Significant long‐term climate trends obtained by DFA were used as predictors of long‐term BAI. 4. The mean BAI was mainly determined by competition, whereas growth trends obtained by DFA did not differ among dominant, suppressed and dying trees. Common trends of growth decline were strongly related to long‐term, late‐winter to summer temperatures, while the residuals were related to total annual precipitation, although with decreasing significance as competition increased. Our results support the contention that the reported patterns of A. pinsapo growth decline and death occur as a result of the interacting effects of both competition and climate stressors acting at long‐ and short‐term time scales. 5. Synthesis. Long‐term climatic drought stress was the main driving factor of growth decline in A. pinsapo. Moreover, trees already suffering from competition (a long‐term stress) were predisposed to decline given an additional short‐term stress, such as a severe drought.

Variation In Resource Availability Changes The Impact Of Invasive Thistles On Native Bunchgrasses

The threat posed by invasive nonnative plants to native plant populations is one of the largest challenges facing both conservation biology and restoration ecology. California has been highly impacted by invaders, although many relict stands of native plants are found on shallow, rocky soils with limited resources. The abiotic conditions of these sites may strongly influence the performance of an invasive plant and its effect on resident native species. In addition, the maturity of native plants in these sites may modulate an invader's impact; larger, well-established plants may be better able to resist invaders. In this study we examined how the impact of an invasive thistle (Centaurea solstitialis) on a native perennial bunchgrass (Nassella pulchra) changed in response to variation in soil depth, soil water availability, and bunchgrass maturity. We measured plant performance in terms of survival, growth, reproduction, and predawn water potential. We found that soil depth, water availability, and bunchgrass maturity acted in concert to influence the impact of the invasive thistle on the native bunchgrass. Both species performed better in deep soils, especially during dry years. The combination of shallow soil and low water availability reduced C. solstitialis performance and ameliorated its negative effect on N. pulchra growth and reproduction. Higher water availability resulted in a stronger negative effect of C. solstitialis on N. pulchra in both shallow and deep soils. However, as N. pulchra matured and increased in size, we saw a steady decline in C. solstitialis growth and reproductive output. Higher water availability increased the performance of C. solstitialis in shallow soils. C. solstitialis may thus have a stronger impact on N. pulchra and be more able to invade relict stands of N. pulchra in shallow soils during high-rainfall years. However, established stands of N. pulchra appear to be more resistant to invasion by C. solstitialis as N. pulchra plants grow older and larger.

SEA-LEVEL RISE AND COASTAL FOREST RETREAT ON THE WEST COAST OF FLORIDA, USA

We investigated patterns, rates, and mechanisms of forest replacement by salt marsh in relation to sea-level rise on the west coast of Florida, USA. The geomorphology of this region typifies that of low-lying, limestone coastlines considered highly susceptible to sea-level rise (e.g., much of the eastern Gulf of Mexico, the Yucatan Peninsula, and low-lying limestone islands throughout the world). This coast is microtidal, shallowly sloping, and has a rate of relative sea-level rise similar to that of eustatic rise. To determine patterns of forest change in relation to sea-level rise, we examined patterns of tree species zonation, tree recruitment, and tree mortality in relation to site elevation and tidal-flooding frequency. To reconstruct histories of forest change in relation to sea-level rise, we estimated age distributions of Sabal palmetto, the most widely distributed tree species at our site, relating age structures of stands to reconstructed histories of tidal flooding in the stands. Finally, to assess the relative roles of flooding stress (hypoxia), salt exposure, and competition from encroaching salt-marsh vegetation in the decline of forest stands, we examined patterns of soil redox potential, groundwater salinity, and density of halophytic vegetation among stands in different stages of decline. Zonation among tree species was related to tidal-flooding frequency. For most trees, seedlings were absent from the most frequently flooded stands in which the species occurred. Reconstructed flooding histories of stands and age estimates for S. palmetto suggest that many decades elapse between cessation of regeneration and local elimination of a tree species. Even during the relatively short duration of the study (4 yr), however, composition of some stands changed in the direction predicted from species zonation and sea-level rise. Forest understory replacement by halophytic vegetation appeared to follow, rather than cause, failure of tree regeneration. Tidal flooding rarely produced severe reducing conditions in soil, but groundwater salinity was correlated with tidal-flooding frequency. Forest retreat in this system, therefore, involves the development of relict (non-regenerating) stands of different tree species at different flooding frequencies. Exposure to salt appears to be the major cause of tree regeneration failure, with flooding stress and interference from marsh vegetation playing minor or negligible roles. These interactions differ somewhat from those on deltaic coasts or coasts with high freshwater outflows, where flooding stress may play a larger role in regeneration failure, and from sandy coasts, where erosion may play a larger role in forest retreat. Regardless of the cause of tree regeneration failure, the development of relict stands may be a general forest response to sea-level rise.

Long‐Term Patterns in Coastal California Grasslands in Relation to Cultivation, Gophers, and Grazing

Grasslands at the Hastings Natural History Reservation (HNHR) and in adjacent Santa Lucia coastal range of Monterey County, California were sampled from 1971 to 1991. Grasslands on HNHR showed two distinct and stable associations: stands with and without historical cultivation (≈ 1865‐1937$). Relict stands dominated by native, perennial grasses (e.g., Nassella pulchra, Poa secunda) are limited to uncultivated, steeper stands, often where soils have more clay. Abandoned agricultural fields have stable compositions dominated by Avena fatua, Bromus mollis, B. diandrus, Erodium spp., Hypochaeris glabra, Vulpia spp., Eremocarpus setigerus, and Amsinckia spp. Patterns in species composition were associated with gradients in soil texture, gopher abundance, and slope. Gophers provide a significant and continuous source of soil disturbance and may slow successional processes in old fields. Where gophers are excluded, aboveground biomass accumulates. Germination and establishment of native perennial grasses (compared to introduced, annual grasses) are reduced on gopher tailings in old fields. Species composition patterns reflecting past cultivation on both grazed and ungrazed stands are apparent. Relict (uncultivated) stands of native grasses persist under many historical levels of grazing. Effects of grazing are often only seen on old fields, and not on relict grasslands. Compared to stands where grazing was removed in 1937, stands currently or recently grazed by cattle show higher soil nitrogen, but reductions in cover of gopher tailings, species diversity, soil phosphate, and sulphate.

A Comparison of Limber Pine (Pinus flexilis) Ages at Lower and Upper Treeline Sites East of the Continental Divide in Colorado

-A series of isolated woodlands, composed largely of limber pine (Pinus flexilis), occupy an escarpment of the western Great Plains that extends from southeastern Wyoming into northeastern Colorado. Previous workers suggested that these limber pine stands are Pleistocene relicts. Although we and other investigators have reported limber pines more than 1500 yr old in the Rocky Mountains, we failed to find limber pines over 200 yr old in any of the Great Plains stands. Demographic similarities among all of the escarpment populations indicate that common factors control tree age in these stands. The stands also generally lack remnants of dead trees, and this suggests that they might represent recently founded populations. Alternately, they may be relict stands in which tree ages are limited and remnants removed by disturbances such as fires, droughts and logging. Partial support for the latter hypothesis comes from an elevational trend in limber pine ages E of the Continental Divide, in which maximum ages generally increase with elevation in response to decreasing stand disturbance frequency.

Stand biomass dynamics of pine plantations and natural forests on dry steppe in Kazakhstan

Biomass dynamics were studied in isolated relict stands of Scots pine (Pinus sylvestris L.) on the dry steppe of Kazakhstan (53–54° N), where potential evaporation is 500–600 mm yr−1 and the rainfall is 250–260 mm yr−1. Samples were taken from seven plots in natural stands on sandy forest soils (aged 13–110 yrs) and ten plots in plantations on dark‐chestnut‐coloured soils (aged 5–50 yrs). Nine or ten sample trees were taken from each plot, giving a total of 68 and 96 sample trees in natural and plantation stands respectively. Root systems were excavated and fractionated in 11 plots. Analyses indicated that the stability of these stands becomes critical at 10–20 yrs, when foliage biomass reaches its maximum (7–13 t ha−1 dry weight), both in plantations and natural stands. Self‐regulating mechanisms in natural stands provide stability that may not develop in some plantations. Natural stands may show an abrupt decrease in foliage biomass at the time of canopy closure, but it increases again by age 40–50 yrs....

Major pests of man-made forests in israel: origin, biology, damage and control

The important pests of the three main tree genera used in afforestation in Israel are described. The pine pests are the Israeli bast scale,Matsucoccus josephi; the pine processionary caterpillar,Thaumetopoea wilkinsoni; the bark beetlesOrthotomicus erosus, Pityogenes calcaratus andTomicus destruens; and the Mediterranean shoot moth,Rhyacionia buoliana thurificana. The cypress pests are the bark beetlesPhloeosinus armatus andP. aubei. The eucalypt borerPhoracantha semipunctata is the sole significant pest of eucalypts. All of these pests, except for the last, are considered endemic species which maintained themselves in the natural relict stands. Routine chemical control operations are conducted only againstT. wilkinsoni. Natural enemies are capable of keeping the other pest populations under good control if appropriate silvicultural measures and practices are in use.

Remnant Grassland Vegetation and Ecological Affinities of the Upper Coastal Prairie of Texas

-Little bluestem (Schizachyrium scoparium), brownseed paspalum (Paspalum plicatulum), and Indiangrass (Sorghastrum nutans) dominate remnant upland grasslands of the Upper Coastal Prairie of Texas. Lowlands are dominated by eastern gammagrass (Tripsacum dactyloides) and switchgrass (Panicum virgatum). Composition and flora of uplands are similar to those of communities over loamy Alfisols of the Fayette Prairie, a southern outlier of the Blackland Prairie. Coastal Prairie lowlands are also similar to lowlands of the Fayette Prairie. Fayette Prairie communities over Alfisols show less similarity to Fayette Prairie communities over clayey Vertisols than to Upper Coastal communities over both soil types. Therefore, the Upper Coastal Prairie should be considered part of a north-south continuum of tall grass communities within Texas. Decreased importance of big bluestem (Andropogon gerardii) and sideoats grama (Bouteloua curtipendula) and an increased importance of brownseed paspalum in the uplands represent the most significant differences in dominance relationships between Upper Coastal Prairie remnants and remnants over Vertisols within the Fayette Prairie. This shift in dominance relationships may be the result of decreased precipitation inland coupled with variation in soil type. The Coastal Prairie in Texas can be divided into two sections based on variation in soils and climate. The Lower Coastal Prairie south of the San Antonio River occurs over hyperthermic soils and is in a dry sub-humid to semi-arid moisture region, while the Upper Coastal Prairie occurs over thermic soils and is in a wet sub-humid to humid moisture region (Thornthwaite, 1948; Soil Survey Staff, 1975). Smith (1899), Bray (1906), and Tharp (1926) provided qualitative vegetation descriptions of the entire Coastal Prairie, but no comprehensive quantitative studies exist for remnant grasslands of either the Lower or Upper Coastal Prairie. It is estimated that less than 1% of an original 8 million ha of native grasslands of the entire Coastal Prairie remains in a relatively pristine state (Smeins et al., in press). Extensive surveys of the Coastal Prairie revealed that little relict grassland vegetation exists in the Lower Coastal Prairie, while the Upper Coastal Prairie contained only approximately thirty relict stands. The purpose of this study was to: 1) quantitatively document characteristics of remnant grasslands of the Upper Coastal Prairie, 2) relate vegetation to edaphic and topographic variables, and 3) compare the composition and floristics of these remnants to the Fayette Prairie, which is located to the north and is considered a southern outlier of the Blackland Prairie (Fig. 1). This comparison will elucidate the degree of relationship between the Upper Coastal Prairie and other Texas Prairies (Collins et al., 1975; Diamond, 1980; Smeins and Diamond, 1983). STUDY AREA.-The Upper Coastal Prairie in Texas comprises a narrow strip approximately 50 to 100 km wide from the Louisiana border to the San Antonio River (Godfrey et al., 1973; Smeins SOUTHWESTERN NATURALIST 29(3):321-334 A GUST 28, 1984 This content downloaded from 157.55.39.102 on Sat, 24 Dec 2016 05:12:17 UTC All use subject to http://about.jstor.org/terms The Southwestern Naturalist

Pollen evidence for the protohistoric development of the “big woods” in Minnesota (U.S.A.)

When the presettlement deciduous forest, as described from land-survey notes of 1854–1860, is compared with relict forest stands of today, it is clear that mesic succession has taken place. The “Big Woods”, dominated by Acer and Tilia, has developed from a forest dominated by Ulmus and Quercus with some Tilia and Acer. Two pollen diagrams spanning the past 1,000 years show that this succession was initiated several hundred years before settlement. Three pollen diagrams from the adjacent oak forest suggest a concurrent succession from Quercus savanna, as well as a later increase in mesic elements at the time of settlement. An area that was oak barrens (a type of Quercus savanna) at the time of settlement, now has relict stands of oak forest; the two pollen diagrams from this area suggest the formation of oak forest since settlement. The mesic successions are probably a culmination of a long-term change toward a cooler and moister climate, but a postulated decrease in Indian populations and fires after European contact about 1650 and before settlement could have accelerated the vegetation successions.

Soil and Vegetation Relationships on Four Slopes of the Ogallala Formation in Trego County, Kansas

The Mixed Prairie is the largest of several grassland associations of North America (Weaver and Albertson, 1956) and was first recognized as a distinct plant association by Clements (1920). Many studies of the mixed prairie have been made but only recently have such factors as slope and soils of the various communities been investigated. Very little research has been conducted concerning vegetation occurring on soils of the Ogallala formation in Kansas. The Ogallala formation is a product of old alluvial deposits composed of materials which were weathered from the Rocky Mountains as they were rising above the rest of the continent (Frye, Leonard and Swineford, 1956). Lunsford (1963) and Smith (1963) studied some relict stands of vegetation over this formation on limy upland and breaks range sites, respectively. The purpose of this study was to describe the vegetation on soils developing from the Ogallala formation in west-central Kansas. The vegetation was measured on slopes facing in different directions and on the hilltop to determine the variations that occur. As a result, this study gives some information on the effect of direction of slope on vegetation covering Ogallala mortar beds.