Presence Of Ditches Research Articles

Characteristics of Wild Boar-Damaged Farmland and Assessment of Effectiveness of Prevention Measures in Northeast China.

Although wild boar invasion is a common human-wildlife conflict worldwide, it is difficult to solve. Understanding the characteristics of wild boar invasion into farmland, accurately predicting the areas where wild boar invasions will occur, and implementing effective prevention and control measures are key to effectively alleviating conflicts between humans and wild boars. From 2021 to 2023, we conducted field surveys and experimentally determined the effectiveness of prevention and control measures in the Huanan and Tonghe Counties in order to explore the landscape and farmland factors affecting wild boar invasion, as well as to evaluate the effectiveness of different combinations of prevention and control measures. The results indicate that the mean patch area, patch area coefficient of variation, and forest type edge density show positive linear correlations with the invaded area, which is positively associated with the presence of ditches and negatively correlated with the existence of electronic fences. Meanwhile, there are non-linear relationships between invasion and the edge density of farmland type, the proportion of forests, the Shannon uniformity index, the proportion of residential areas, the distance from the village, the distance from the forest, and the population density. In particular, the risk of wild boar invasion is higher in the border area between forest and farmland. The loss rate of farmland under the different control measures (compound) was significantly lower than that in the electronic fence group (single) (p < 0.05). Based on these findings, we put forward the following suggestions for the prevention and control of wild boar: (1) widen and deepen the narrow landscape elements around farmland; (2) focus on the border area between forest and farmland; and (3) use compound prevention and control measures. This study provides a comprehensive foundation for future wild boar prevention and control research, and it contributes to the formulation of effective wild boar prevention and control policies worldwide.

Effect of Habitat Structure and Crop Diversity on Common and Threatened Birds Breeding in Semi-Natural Field Margins

Field margins are inherent elements of European agricultural landscapes, thought to be crucial for maintaining a high biodiversity level. The interactions between the structure of field margins and biota have been recognized, yet the understanding of the importance of various components of the margins and adjacent areas is still incomplete. The aim of our study was therefore to determine the relative importance of structural features of the margins and diversity of adjacent crops for birds breeding in field margins. The study was carried out in 70 field margins covered with semi-natural vegetation, situated in SW Poland. Both the number of species and bird density were most strongly positively related to the development of tree and shrub layers, while presence of ditches and percentage of reed cover (positive effects) had much less importance. Analyses conducted at the species level revealed the complexity of bird-habitat interactions resulting from various requirements of individual species. Overall, for 22 abundant species and for the threatened species, the development of the shrub layer turned out to be a particularly important feature of field margins positively associated with occurrence of e.g. Emberiza citrinella, Linaria cannabina and Streptopelia turtur. Other significant positive effects had the development of the tree layer (e.g. Turdus merula and Turdus philomelos), presence of ditch (e.g. Acrocephalus palustris, Sylvia communis), and number of gaps in woody vegetation (e.g. Lanius collurio). The diversity of adjacent crops had positive effects only to some threatened species (e.g. L. collurio and E. calandra). Abundances of common and threatened birds were not correlated, which reflects different habitat demands of these two groups. Because of diverse bird-habitat relationships, maintaining a variety of field margins (in particular the shrubby ones), should be accepted as a rule in biodiversity-oriented management of agricultural landscapes.

黄淮平原农业景观鸟类多样性及生境差异

PDF HTML阅读 XML下载 导出引用 引用提醒 黄淮平原农业景观鸟类多样性及生境差异 DOI: 10.5846/stxb201712132246 作者: 作者单位: 河南大学黄河中下游数字地理技术教育部重点实验室;河南大学环境与规划学院,河南大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31600374，41371195）；河南省教育厅科学技术研究重点项目（16A180022）；河南省博士后科研项目（2015049） Bird diversity during the breeding period in different habitats in an agricultural landscape in the Huang-Huai plain Author: Affiliation: Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, Ministry of Education, Henan University, Kaifeng, China; College of Environment and Planning, Henan University, Kaifeng, China,School of Life Sciences, Henan University, Kaifeng, China Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 31600374, 41371195 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:农业景观中的鸟类多样性对生态系统功能和服务的形成与维持具有重要作用。黄淮平原区是我国最重要的农业景观区之一，为探讨区域内农业景观中鸟类多样性特征和不同生境间的差异，在研究区农业景观不同生境中布设样点，调查繁殖期鸟类多样性特征。结果显示：（1）共记录到32科、49属、66种的10044只个体，但优势科属明显；（2）物种丰富度、多样性和均匀度均表现出在沟渠、湖泊生境中较高，农田和村庄生境中相对较低，但物种多度呈现出村庄生境中最高，其次是沟渠和农田生境，湖泊生境中最低；（3）在区系分布上，各生境中均以广布种为主，生态类群上，鸣禽在各生境中均占绝对优势，涉禽和游禽主要分布在沟渠和湖泊生境中，从居留型来看，留鸟是各生境中的主导类群，候鸟、旅鸟和迷鸟比例很低；（4）鸟类群落异质性分析显示，各生境间的相似性总体上较高，表明区域内农业景观中鸟类组成具有较高的重叠性。研究显示农业景观中湖泊和沟渠的存在能有效的提高区域鸟类的丰富度和多样性，而沟渠的存在能有效的提高鸟类个体多度，农田和村庄有助于特定类群多度的增加，因此在未来的区域持续农业景观的构建中一方面要重视自然、半自然非农生境的作用，另一方面也不能忽视不同生物类群对景观异质性响应和对生境特征需求的差异。 Abstract:The diversity of birds in agricultural landscapes plays an important role in the formation and maintenance of ecosystem functions and services. The Huang-Huai plain is among the most important agricultural areas in China. With the continuing expansion of agricultural lands and the intensification of land-use, bird diversity in agricultural landscapes is declining all worldwide. To explore the diversity of birds in different habitats of the agricultural landscape in the Huang-Huai plain, we set up transects across different habitats in this area and investigated bird diversity characteristics during the breeding period. Our results showed that:(1) a total of 10044 individuals in 32 families, 49 genera, and 66 species were recorded; however, several families and genera were obviously dominant. (2) Species richness, diversity, and evenness were all higher in the habitats of ditch and lake, and relatively low in habitats of farmland and village. However, species abundance was highest in the village habitat, followed by ditch and farmland habitats, whereas in the lake habitat it was the lowest. (3) Analysis of faunal distribution showed that cosmopolitan species dominated any given habitat. In terms of ecological groups, the songbirds were the dominant species in all habitats, whereas the waders and swimming-birds were mainly distributed in the ditch and lake habitats. In terms of residence type, however, residents formed the dominant group in all habitats, and migrators, travelers, and stragglers appeared occasionally. (4) The high community similarity among the habitats indicated that bird species compositions were overlapped substantially across habitats in the agricultural landscape. Overall, the habitats of ditch and lake in the agricultural landscape could effectively improve the regional species richness and diversity, and the presence of ditches could further increase the abundance of birds, whereas the habitats of farmland and village may only enhance the abundance of specific bird species. This study emphasized the potential contributions of natural and semi-natural habitats to the construction of a sustainable agricultural landscape in the future; however, the differences in the responses to landscape heterogeneity and habitat requirements of different biological groups should not be ignored. 参考文献 相似文献 引证文献

Applying trait-based community metrics of relevance to conservation for understanding community patterns of farmland birds in Northwest Russia

Use of community trait-based metrics has been increasingly implemented for achieving an integrated view of biodiversity in conservation planning. We examined the extent, to which the use of community metrics based on species traits reflecting plausible sensitivity to change would contribute to our understanding of landscape characteristics of importance to the conservation of farmland birds in a poorly studied region of Northwest Russia. We collected species data on farmland from 230 transects covering a total 215 km for each year of 2008, 2010 and 2011 and analysed them using generalised linear mixed modelling. We derived community indices from species traits of habitat specialisation, trophic position, relative brain size and body mass. By relating these indices to the numbers of all species regarded farmland and Species of European Conservation Concern (SPEC), and by analysing them against the type of field and occurrence in typical non-cropped landscape elements, we showed consistent, albeit weak, congruence among the taxonomic and trait-based community descriptors. All community descriptors had their lowest estimates in arable fields. Community specialisation was the highest in open abandoned fields, which confirms the importance of such fields as refuges for regionally specialised species. Pastures were characterised by the highest community biomass, which indicates a particularly good resource base. Presence of ditches, of all non-cropped elements, had the strongest positive relationship with the community descriptors. The SPEC number strongly correlated with the overall species richness of farmland birds. A relatively weak congruence between taxonomic and trait-based community descriptors highlights their complementarity in understanding the underlying mechanisms of community changes. However, similarity in patterns among field types means that, under the current level of production in the region, accounting for the species richness of farmland birds seems to be sufficient to rapidly assess community sensitivity to agricultural change.

Dispersal and local environment affect the spread of an invasive apple snail (Pomacea maculata) in Florida, USA

Dispersal and local environmental factors are major determinants of invasive species distribution. We examined how both dispersal-related geospatial characteristics and environmental factors influence an ongoing invasion of wetlands in a south-central Florida ranchland by non-native apple snails (Pomacea maculata, Ampullariidae). We found P. maculata in 73 (43%) of a random set of 171 wetlands in 2014. We used model selection to evaluate multiple hypotheses of predictors of P. maculata occurrence in 95 wetlands with standing water, including spatially-explicit distances in ditches from wetlands to the presumed entry point, Euclidean (overland) distances, presence/absence of ditches in wetlands, and environmental variables (e.g. pH). We also performed a 5-month field experiment in 20 wetlands to evaluate if snail absence was associated with conditions that limit survival and growth (i.e. unfavorable habitats). Snail occurrence was primarily associated with presence of ditches in wetlands and more neutral wetland pH. These variables more plausibly explained snail occurrence than did Euclidean (overland) distance and minimum ditch travel (rectilinear) distance from propagule sources (a major waterway). Wetland pH best explained survival and growth under the experimental conditions. We found no evidence that prior occupancy by conspecifics affected survival and growth, suggesting that dispersal limitation may contribute to lack of occupancy of wetlands, despite suitable pH. Our study supports man-made conduits as facilitators of dispersal by non-native species, where environmental characteristics (here pH) then also affect colonization within habitats. An understanding of both dispersal mechanisms and local environmental factors is necessary to better predict invasive species distribution.

Identification of ditches and furrows using remote sensing: application to sediment modelling in the Tana watershed, Kenya

ABSTRACTRidge-tillage is an agricultural practice where crops are planted on elevated ridges, with furrows in-between. Ridge-tillage has been shown to significantly reduce erosion from croplands, but data on the presence of ridge-tillage is sparse and challenging to collect at the landscape scale. Thus, water quality models often do not account for ridge-tillage in a spatially-explicit manner, potentially overlooking the important impacts of this practice. We have developed a novel method that exploits the spectral, radiometric and linearity shape characteristics to identify both drainage ditches and ridge-tillage furrows using remote sensing of 0.5 m satellite data. We applied the method to the Sasumua watershed in Kenya, where we had false positives in only 3% of randomly selected polygons, and we detected the majority of ditches in 59% of randomly selected polygons. We then assessed the potential value of including these data in sediment modelling, showing that representing these practices could reduce sediment export in the study area by roughly 80%. Being able to readily identify the presence of ditches and furrows could enable the development of more accurate water quality models, and help identify priority areas for intervention to improve water quality (and possibly crop yields) through changing agricultural practices or policies.

Spatio-temporal dynamics of generalist predators (Tetragnatha spider) in environmentally friendly paddy fields

Earlier studies showed environmentally friendly farming (EFF) increased the populations of various organisms in agricultural landscapes, but the mechanisms of these increases were not well studied, due to a lack of knowledge on their temporal dynamics. Here, we examined spatio-temporal dynamics of Tetragnatha spiders, natural enemies of rice pests, in EFF and conventional farming (CF). Field surveys were conducted in 15 paddy fields under CF and 18 under EFF during three seasons in Tochigi Prefecture, central Japan. The results showed that Tetragnatha spiders were more abundant in paddy fields than in ditches during the growing season, but this tendency was reversed during the non-crop season. Thus, complementary utilization of ditches and paddy fields during different seasons appeared to maintain Tetragnatha populations. Both Tetragnatha spider and flying insect abundance increased in paddy fields under only EFF when the surrounding forest cover was high. There was a significant positive correlation between the density of flying insects and the population growth rate of Tetragnatha spiders, suggesting a bottom-up effect of flying insects emerging from paddy fields. We concluded that the high potential productivity in paddy fields, coupled with the presence of ditches as important habitats, maintained the high abundance of Tetragnatha spiders in paddy-dominated landscapes.

How do ditches contribute to bryophyte diversity in managed forests in East-Central Europe?

The study focuses on identifying and assessing the effect of the presence of drainage and roadside ditches on the diversity of bryophytes in managed forests. We compared the composition of moss and liverwort species, their richness and abundance in plots that are located in ditches as well as corresponding control plots in the surrounding forests with regard to the forest type (coniferous, mixed and deciduous). ANOVA demonstrated the pronounced impact that the presence of ditches in managed forests has on an increase in bryophyte species richness. A comparison of forest and ditch types using DCA pointed to a correlation between the number of deciduous trees in the stands and an increased dissimilarity of ditch bryophytes when compared to the bryophytes of the corresponding control plots. Using the ecological indicator values, CCA confirmed the special significance of ditch settlements for hygrophilous species, which at present cannot otherwise find favorable conditions in managed forests. The study proves that ditches, and especially those with intermittent pools of stagnant water, may become a significant source of microhabitat diversity. Their presence may provide a welcome preserve for rare and protected species that cannot find suitable substrates in managed forests.

The Spread of Non-native Plant Species Collection of Cibodas Botanical Garden into Mt. Gede Pangrango National Park

The role of botanic garden in spread of non-native plant species has concerned of international worldwide. This study aimed to study the extent of non-native plant species from Cibodas Botanical Garden (CBG) which invades into natural rainforest. A line transect was made edge-to-interior with 1,600 m in distance from CBG boundary. Result showed that distance from CBG was not significant in correlation with non-native tree and treelet density. Furthermore, presence of existing CBGs plant collection was not a single aspect which influenced presence and abundance. Three invasive species possibly was escape from CBG and it showed edge-to-interior in stems density, i.e. Cinchona pubescens, Calliandra calothyrsus and Cestrum aurantiacum. The patterns of non-native species were influenced by presence of ditch across transect, existence of human trail, and the other non-native species did not have general pattern of spread distribution. Overall, botanical gardens should minimize the risk of unintentional introduced plant by perform site-specific risk assessment.

The importance of drainage ditches for farmland birds in agricultural landscapes in the Baltic countries: does field type matter?

Land drainage exhibits a considerable impact on biodiversity. Drainage ditches-a regionally common landscape element-carry a number of benefits for birds associated with farmland. The aim of this study was to quantify a relative value of ditches for farmland birds depending on the type of surrounding fields. Survey data on farmland bird communities and farmland landscape structure across Estonia, Latvia and Lithuania were used. Count plots were situated within either arable fields or grasslands, or their combination and contained two types of ditches, with grassy margins or with tall vegetation such as bushes and trees. Focal species were selected based on their plausible use of ditches. Species richness and abundance of farmland birds were positively associated with the presence of ditches with tall vegetation, but the plausible role of ditches with only grassy margins remained unclear. For some species, the relationship was more pronounced in arable land than in grassland. Regional agricultural policy should support the retention of ditches, especially those with complex structure, in farmland. This action is crucial in landscapes dominated by crop production, as they face the most intense utilisation.

Effectiveness of the GAEC cross-compliance standard Short-term measures for runoff water control on sloping land (temporary ditches and grass strips) in controlling soil erosion

The agronomic measures made obligatory by the cross-compliance Standard Temporary measures for runoff water control on sloping land included in the Ministry of Agricultural, Food and Forestry Policies (MiPAAF) decree on cross compliance until 2008, and by Standard 1.1 Creation of temporary ditches for the prevention of soil erosion in the 2009 decree, certainly appear to be useful for the control of soil erosion and runoff. The efficacy of temporary drainage ditches and of grass strips in controlling runoff and erosion has been demonstrated in trials conducted in field test plots in Italy. When level temporary drainage ditches are correctly built, namely with an inclination of not more than 2.5% in relation to the maximum hillslope gradient, they allow the suspended sediment eroded upstream to settle in the ditches, retaining the material carried away on the slope and, as a result, reducing the quantity of sediment delivered to the hydrographic network. In particular, among all the results, the erosion and runoff data in a trial conducted in Guiglia (Modena) showed that in corn plots, temporary drainage ditches reduced soil erosion by 94%, from 14.4 Mg ha-1 year-1 (above the limit established by the NRCS-USDA of 11.2 Mg ha-1 year-1) to 0.8 Mg ha-1 year-1 (within the NRCS limit and also within the more restrictive limit established by the OECD of 6.0 Mg ha-1 year-1). With respect to the grass buffer strips the most significant research was carried out in Volterra. This research demonstrated their efficacy in reducing erosion from 8.15 Mg ha-1 to 1.6 Mg ha-1, which is approximately 5 times less than the erosion observed on bare soil. The effectiveness of temporary drainage ditches was also assessed through the application of the Revised Universal Soil Loss Equation (RUSLE) erosion model to 60 areas under the control of the Agency for Agricultural Payments (AGEA) in 2009, comparing the risk of erosion in these sample areas by simulating the presence and absence of drainage ditches at a distance of 80 metres from each other as required by the Standard. The results of the scenario analysis showed that the presence of ditches on average decreases erosion by 67%. To sum up, the Standard was found to be effective from a hydraulic point of view, as the results have demonstrated the adequacy of temporary ditches for the control of runoff water. Another important result of this study was the production of a simple equation that can be directly used by farmers or, more realistically, by the farm advisory system to provide farmers with the information necessary for the realisation of temporary drainage ditches (depth and section that can be obtained with the most widespread types of ditch diggers) so that these ditches are effective and maintain their hydraulic efficacy throughout the entire cropping period. This equation would also be useful for cross-compliance control by the AGEA and regional control bodies.

Species richness and composition of bird communities in various field margins of Poland

A study was conducted to determine the occurrence of bird species in relation to 70 field margins of an agricultural landscape in SW Poland. Three types of margins were divided according to the volume of tall vegetation, i.e. herbaceous, shrubby, and tree lined. Fifty breeding bird species were recorded, with a mean density of 33.2 pairs/km. The dominant species were non-threatened and were characteristic of forests or of the field-forest mosaic. Tree lined margins showed the highest abundance and bird species richness. Shrubby margins supported the second highest, while open habitats ranked last. Abundances in ecological guilds were affected by the margin type, the presence of field roads, and especially the presence of ditches in the margin structure. Redundancy Analysis showed clear differences in bird communities between the discernable types of field margins. Species richness increased in the combinations of various margin types. In heterogeneous farmland environmental policy should aim at maintaining various types of field margins at high density in the agricultural landscape.

Avian fauna in windbreaks integrating shrubs that produce non-timber forest products

Windbreaks are well known for their environmental benefits on agriculture but the diversity of the wildlife they support remains to be investigated. Therefore, avian diversity was studied during the spring and fall of 2005 and 2006 on farmlands in eastern Québec, Canada. The study focused on 12-year-old windbreaks, half of which comprised shrubs that produce non-timber forest products (NTFP). The main objectives were (1) to determine whether the introduction of NTFP into windbreaks influences bird abundance, richness and diversity; (2) to verify if NTFP attract potentially detrimental birds; and (3) to determine the habitat variables that best explain the use of windbreaks by birds. Traditional windbreaks ( n = 7) were composed of larches ( Larix laricina (Du Roi) Koch.) alternating with ashes ( Fraxinus pennsylvanica Marsh. or Fraxinus americana L.), while the windbreaks with shrubs that produce NTFP ( n = 7) included American elderberries ( Sambucus canadensis L.) and highbush cranberries ( Viburnum trilobum Marsh.) instead of L. laricina. No difference was found in bird abundance, diversity or richness between the two types of windbreaks, except for greater richness during springtime in windbreaks without NTFP, probably due to larches providing greater tree cover. In both windbreak types, the vast majority (>94%) of the birds belonged to the non-detrimental bird class. Bird use was positively influenced by the presence of ditches along the windbreak.

Pianificazione delle operazioni di esbosco in un ceduo

Abstract: A series of cartographic models of analysis have been elaborated through the softwares ArcView GIS (ESRI 2002) and Surfer 8 (Golden Software 2002) to find optimal work systems for the wood extraction in an oak coppice, located on the Monti della Tolfa, near Rome, Italy. The main factors analyzed were the morphology of the territory and the roads characteristics. The methodological procedure followed was applied on the different classes of slope, the direction of water outflow, the presence of ditches and channels, the principal and secondary roads, the wood cover and the clearings. The possibility to employ tractors with cages, polyethylene chutes, mules and cable cranes has been examined, also identifying the fittest areas to their use. This first analytical phase was followed by a second phase dedicated to the evaluation of the technical feasibility. The proposed method contributes to a rational planning of the work site. The advantage could be the planning of extraction operations on the map, but it will be necessary to verify the method in field studies. Although this method has been developed on limited extensions of territories, it could be applicable to situations of greater complexity, representing the base for the creation of a tool that may be employed in ampler territorial contexts, such as Comunita Montane and hydrographic basins.

Drainage Ditches Facilitate Frog Movements in a Hostile Landscape

Ditches are common in landscapes influenced by agricultural, forestry, and peat mining activities, and their value as corridors remains unassessed. Pond-breeding amphibians can encounter hostile environments when moving between breeding, summering, or hibernation sites, and are likely to benefit from the presence of ditches in the landscape. Within a system consisting of ditch networks in bogs mined for peat in eastern New Brunswick, Canada, I quantified the breeding, survival, and movements of green frogs (Rana clamitans melanota) in drainage ditches and also surveyed peat fields. Frogs rarely ventured on peat fields and most individuals frequented drainage ditches containing water, particularly in late summer. Though frogs did not breed in ditches, their survival rate in ditches was high (88%). Ditches did not hinder frog movements, as frogs moved independently of the current. Results indicate that drainage ditches containing water enable some movements between habitats isolated by peat mining, in contrast to peat surfaces, and suggest they function as amphibian movement corridors. Thus, such drainage ditches may mitigate the effects of peat extraction on amphibian populations. At the very least, these structures provide an alternative to hostile peat surfaces. This study highlights that small-scale corridors are potentially valuable in population dynamics.

Heterogeneous nucleation in the crystallization of polyolefins. III. Theory and mechansim

AbstractThe nucleating activity of a large number of nucleating agents for the crystallization of polyolefins is not based on a high surface free energy of the substrate or on epitaxy, or on a minimum particle size just compatible with the thickness of the crystallizing polymer lamellae, or on any persistance of crystalline material in holes of the nucleating particles. The relevant mechanism is thought to be nucleation at steps of limited length in the surface of the nucleating particles. The nucleation is enhanced by a high degree of accommodation of polymer molecules at the surface of the substrate through the presence of ditches in the latter which cause prealignment of polymer chains and thus facilitate crystallization.

Occupying the Wet Prairie: The Role of Artificial Drainage in Story County, Iowa

0OME attention by geographers to the statistics from three United States censuses of drainage and to the chapter on reclamation of wet and overflow lands in a textbook on conservation' has led to the realization by a part of the geographical profession that there is considerably more drained land than irrigated land in the United States and that the major portion of the drained land forms a relatively continuous arc from southeastern Michigan and northwestern Ohio, through Indiana, Illinois, and Iowa to the northwestern corner of Minnesota. This great arc of drained land for over two-thirds of its length runs through the prairie. The great extent of naturally wet land in the Midwestern prairie, the fact of the reclamation of the wet land, and the results of the reclamation are all comparatively unknown. The common unawareness of the drainage of formerly wet land on the part of the American public and geographers alike is in contrast to the interest in the irrigation of dry land. The unequal attention given irrigation and drainage may be explained in two main ways. 1) Irrigation produces marked local areal differentiation; whereas, drainage reduces local differences in landscape appearance and use. 2) The fact of irrigation is usually evident in the presence of ditches and men at work directing the flow of water whereas most artificial drainage takes place automatically through tile buried in the ground. It is the purpose of this paper to examine in some detail the character of the occupation and utilization of a small portion of the poorly drained prairie in the north central portion of the United States, on the assumption that some generalizations may be discovered that can be tested later in a larger setting. The area selected, Story County, Iowa, is representative of the Iowa wet prairie. It lies within the Mankato Lobe of late Wisconsin glaciation, the major region of poor drainage in the state (Fig. 1). Like the larger region, it contains both till plain flats of extensive poor drainage and undulating to gently rolling land marked by numerous small poorly drained depressions. The amount and arrangement of naturally wet prairie land varies greatly within the county, facilitating the comparison of wetter and less wet areas. Because Story County lies at the southeastern edge of the major area of wet prairie in the state, it was among the first of the fairly wet counties of the state to be settled. Accordingly, the record of drainage may be the more meaningful because of the length of time involved.