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1.
Successful Mormon colonization of the American West has largely been attributed to the adaptive advantage of cooperative Mormon values. This article shows that successful Mormon colonization of the Little Colorado River Basin had an ultimate ecological basis: the redistribution of surplus resources among settlements situated in dispersed and functionally independent local environments. Two systems of resource redistribution among 19th-century Little Colorado Mormon settlements are examined, showing that ecological considerations explain their differential success as adaptive mechanisms contributing to the success of this local colonization effort. The article concludes by suggesting that general ecology provides a useful theoretical framework for explaining successful Mormon colonization in this region and elsewhere.  相似文献   

2.
A dynamic model of nematode populations under a crop rotation that includes both host and nonhost crops is developed and used to conceptualize the problem of economic control. The steady state of the dynamic system is used to devise an approximately optimal decision policy, which is then applied to cyst nematode (Heterodera schachtii) control in a rotation of sugarbeet with nonhost crops. Long-run economic returns from this approximately optimal decision rule are compared with results from solution of the exact dynamic optimization model. The simple decision rule based on the steady state provides long-run average returns that are similar to the fully optimal solution. For sugarbeet and H. schachtii, the simplified rule can be calculated by maximizing a relatively simple algebraic expression with respect to the number of years in the sequence of nonhost crops. Maximization is easy because only integers are of interest and the number of years in nonhost crops is typically small. Solution of this problem indirectly yields an approximation to the optimal dynamic economic threshold density of nematodes in the soil. The decision rule requires knowledge of annual nematode population change under host and nonhost crops, and the relationship between crop yield and nematode population density.  相似文献   

3.
The reasons why some plant species were selected as crops and others were abandoned during the Neolithic emergence of agriculture are poorly understood. We tested the hypothesis that the traits of Fertile Crescent crop progenitors were advantageous in the fertile, disturbed habitats surrounding early settlements and in cultivated fields. We screened functional traits related to competition and disturbance in a group of grass species that were increasingly exploited by early plant gatherers, and that were later domesticated (crop progenitors); and in a set of grass species for which there is archaeological evidence of gathering, but which were never domesticated (wild species). We hypothesised that crop progenitors would have greater seed mass, growth rate, height and yield than wild species, as these traits are indicative of greater competitive ability, and that crop progenitors would be more resilient to defoliation. Our results show that crop progenitors have larger seed mass than wild species, germinate faster and have greater seedling size. Increased seed size is weakly but positively correlated with a higher growth rate, which is primarily driven by greater biomass assimilation per unit leaf area. Crop progenitors also tend to have a taller stature, greater grain yield and higher resilience to defoliation. Collectively, the data are consistent with the hypothesis that adaptations to competition and disturbance gave crop progenitors a selective advantage in the areas surrounding early human settlements and in cultivated environments, leading to their adoption as crops through processes of unconscious selection.  相似文献   

4.
For several decades researchers have debated when cereal cultivation was introduced to northernmost Europe. Most previous studies have concentrated on sites along the coast or close to major rivers; these are areas well-suited to agriculture and represent routes for people and knowledge transfer, but omit other vast areas suitable for cultivation and sedentary settlement. Here, we present strong evidence of permanent cultivation from ad 480 onwards at a settlement located at the 64th parallel North in northern Sweden, currently situated 30 km inland from the Gulf of Bothnia. This predates the beginning of permanent cultivation at sites along the present coastline mentioned here and in results from previous studies of places at approximately the same latitude. Our results are based on continuous finds of cereal pollen grains at certain sites, selected on the basis of archaeological records, old maps, plus past and present elevations above sea level. We highlight the importance of taking factors into account such as access to waterways, communication routes and coast displacement following land uplift when choosing study sites in order to pinpoint early cultivation and sedentary settlements. We suggest that these results have implications for attempts to resolve the question of the history of early agriculture in other parts of northern Fennoscandia.  相似文献   

5.
Several urban medieval sites in Finland (ad 1000–1500) have been archaeobotanically investigated, but until now only a few rural medieval settlements have been studied. Therefore, many aspects of the crops and agricultural methods of medieval villages in Finland still remain unknown. At the 12th to mid-16th century medieval village of Mankby, Espoo, a systematic sampling for archaeobotanical material was carried out. The analysed samples derived from hearths, building contexts and medieval field layers etc. The archaeobotanical material was carbonised, and it consisted mostly of conifer needles, cereal grains and weed seeds. Secale cereale (rye) and Hordeum vulgare (barley) were the only crop species found, Secale being the most frequent. Seeds of Bromus secalinus (rye brome) and achenes of Centaurea cyanus (cornflower), which are associated with autumn sown winter cereal crops, were also present. The archaeobotanical material shows areas of activity linked to storing crops, as well as cultivation within the village boundaries. Based on radiocarbon dated grains, cultivation of the fields started in the 12th century and continued until the abandonment of the village in 1556. Archaeobotanical material from Mankby has been compared to other contemporary sites in Finland, and differences between the sites can be seen. Results from Mankby have added to our knowledge of medieval agriculture, past areas of activity and economic conditions within the village.  相似文献   

6.
A direct relationship exists between soil temperature and Heterodera schachtii development. The average developmental period of two nematode populations from Lewiston, Utah, and Rupert, Idaho, from J2 to J3, J4, adult, and the next generation J2 at soil temperatures of 18-28 C were 100, 140,225, and 399 degree-days (base 8 C), respectively. There was a positive relationship (P < 0.05) between nematode Pi, nematode generations, and sugarbeet yields. The greatest sugarbeet growth inhibition (87%) occurred when sugarbeets were exposed to a Pi of 12 eggs/cm³ soil for five generations (1,995 degree-days), compared with a 47% inhibition when plants were exposed to the same Pi for two generations. There was a negative correlation (P < 0.05) between the Pi, Pf, and sugarbeet yield for each population threshold. The smaller the Pi, the greater the sugarbeet yields and the greater the Pf. Root yields were 80 and 29 t /ha and Pf were 8.4 and 3.6 eggs/cm³ soil when sugarbeet seeds were planted at Pi of 0.4 and 7.9 eggs/cm³. respectively, at a soil temperature of 8 C. The number of years rotation with a nonhost crop required to reduce the nematode population density below a damage threshold level of 2 eggs/cm³ depends on the Pi. A Pi of 33.8 eggs/cm³ soil required a 5-year crop rotation, whereas a Pi of 8.4 eggs/cm³ soil required a 2-year crop rotation.  相似文献   

7.
The assemblage of carabid species trapped over a 3 yr period in eight separate but contiguous fields was analysed by Canonical Correspondence Analysis (CCA), Seven of the fields were subject to arable crop rotations involving a mixture of autumn and early spring‐sown cereals (wheat or barley), late spring‐sown crops (potatoes, sugar and fodder beet and maize) and short‐term uncultivated grass leys, The eighth field was an established ‘permanent’ grass pasture of at least 50 yrs standing, Pooled samples collected in the first half of the growing season (April‐June) showed clear evidence of soil cultivation effects on community structure, Systematic exclusion of samples and re‐analysis distinguished the fauna of firstly, old pasture samples, samples from ley pastures of increasing age and finally samples from fields with different times of soil cultivation, In the latter analysis, the main effects of soil cultivation were related to differences in ground cover over the winter and a direct effect of spring soil cultivation on autumn breeding populations, The ordination of pooled catches for the second half of the growing season (July‐September) could not be related to known year, field or crop cultivation variables, The underlying species ordination suggested that later in the summer the effect of crop cover on soil microclimate may mask cultivation effects by influencing the post‐emergence dispersal of autumn‐breeding populations and the reproductive success of spring‐breeders, The combination of earlier soil cultivation effects, and probably microclimatic influences later in the season, resulted in the strong distinction of whole season carabid catches from individual fields, It is concluded that the uniqueness of individual field histories may provide a mechanism to promote the co‐existence of ecologically similar species within the farmed landscape and enhance the abundance and bio‐diversity of species in the face of routine soil cultivation.  相似文献   

8.
The record of prehistoric crop cultivation in central Europe dates as far back as 5500 bc. In the pile-dwellings of the north-western pre-alpine forelands, dating roughly from 4300 to 800 bc, favourable taphonomic conditions provide evidence for the ways of cereal cultivation and consumption in unmatched detail. Based on different sets of (bio-) archaeological and palynological evidence, different hypotheses of crop husbandry methods have been developed for the wetland settlements. During the late Neolithic, two partly antithetic ideas are discussed: On one hand Shifting Cultivation assumes frequently shifted crop fields and the use of fire to provide nitrogen for plant uptake; On the other hand Permanent Cultivation reconstructs longer-ranging use of the fields, to which nitrogen may have been provided by various means. From the Bronze Age onwards, most probably some form of extensive ard cultivation was applied. In this article, we explore the implications of the different hypotheses for the socio-ecological system of the wetland sites. We combine the capability of agent-based modelling to simulate dynamic processes with the benefits provided by geographical information systems and the possibilities provided by the use of modern agro-ecosystem modelling tools. First, we used a mechanistic crop growth model, MONICA, to evaluate the influence of important factors of prehistoric crop yield formation: the climatic conditions, the soil texture and the degree of nitrogen availability. Second, we applied an agent-based model (WELASSIMO_crops) to simulate the spatial and economic implications related to the different crop husbandry methods. Our results provide quantitative information on the extent of crop husbandry activities in the wetland sites and on the effect of natural and anthropogenic factors on prehistoric crop yields. Without manure application, initial average yields of 1.0 t ha?1 a?1 are shown to decrease rapidly to only 50 % after 10 years. A manuring rate of 10 t ha?1 a?1 allows for higher yields of 1.7 t ha?1 a?1 and a slower rate of fertility decrease, but requires high numbers of livestock per capita. In shifting cultivation, high yields of 2.7 t ha?1 a?1 are reasonable, while necessitating a very large area and high labour input. Using the model results and a case study, we argue that permanent cultivation is more likely to have been the standard method, while burning of the landscape may have had different objectives than crop husbandry. We find that the combination of agent-based social and process-based biophysical modelling is a powerful tool to study the complex interdependencies in human-environment systems in the past.  相似文献   

9.
The history of rye cultivation in Europe   总被引:5,自引:5,他引:0  
During recent years finds from several prehistoric and medieval periods have thrown new light on the history of the spread of rye. It is now proven that wild rye is indigenous to Anatolia and was already domesticated there by the early Neolithic at the beginning of agriculture. Secale migrated to Central Europe as a weed among other cereals, and single grains of weed rye have been recorded there since the early Neolithic. The number of finds increased during the Bronze Age and Iron Age, and the status of rye changed from weed to crop plant, probably in the course of the early Iron Age. This acculturation of Secale cereale in central and eastern Europe was obviously independent of the earlier one in Anatolia. The first stages towards deliberate cultivation happened unintentionally through harvesting close to the ground, so that the rye was permanently represented in the seed corn. From this point rye was able to take advantage of its competitive strength on poor soils and in areas with unfavourable climate. The start of rye as a crop in its own right during the pre-Roman Iron Age and Roman period presumably took place independently in different areas. The expansion of intensive rye cultivation occurred in the Middle Ages. However, new finds from north-west Germany, which are presented here, show that in this area rye has been cultivated as a main crop on poor soils since the Roman period. In two maps all rye finds up to 1000 A.D. are shown, which after critical consideration can be regarded as cultivated rye.  相似文献   

10.
Geographical changes in suitability in England and Wales for the cultivation of potatoes under a climate change scenario were predicted for the years 2023 and 2065 by integrating a climate database (1951-80) with climate-driven crop growth models. Initially, model outputs were produced as point values (meteorological site locations) of predicted potential yields for current crop production. The model outputs were validated statistically using actual crop yield figures collated from bibliographic analysis. The most suitable model was run again incorporating projected temperature and precipitation changes for 2023 and 2065. These outputs were then used to predict possible economic changes to farm profitability and general market trends. Results indicated that, although yields may rise, gross margins for maincrop and especially early potatoes may also rise due to shifts in production, to a fall in overall potato output and to price increases.  相似文献   

11.
湘西传统聚落作为一种为数不多的、保存完好的聚落景观之一,其保护研究是我国文化生态及其生物多样性保护研究的重要组成部分。以怀化市侗族传统聚落为研究对象,从传统风水学理念与现代生态位出发,探索传统聚落空间格局的构建方法和驱动因素,以期为传统聚落合理的生态位扩充和空间结构演变提供理论依据。研究表明:湘西传统聚落形成了东、南、西、北四面山林围护、中间宽敞开阔的独立地理空间结构,构建了符合大众追求的"山-林-屋-水-林"的理想聚落空间模式,而且民居建筑大多都"坐西朝东,背风向阳,靠山面水而建"。这种聚落是在自然、经济和文化三大因素共同影响下构成的复合生态系统,有其独特的运行机制。在传统聚落空间系统不断发展的过程中,应遵从其演变发展的客观规律,根据不同传统聚落的生产力水平条件,合理推进经济社会空间结构的转型,并适度加以调控,以稳步实现传统聚落的空间演变和生态位扩充。  相似文献   

12.
Using a soil debris isolation method, populations of Rhizoctonia solani were monitored over a 4 -yr period in four fields which were initially cropped to sugar beet and in which four areas of Rhizoctonia crown rot diseased beets (DA) and four areas of apparently healthy beets (AH) had been selected and precisely located. Soil from these areas was assayed during the subsequent crops, which included sugar beet, tomato, cucumber, maize and soybean. No significant differences in colony counts were found between the soils in DA and AH on any of 30 sampling dates. R. solani population counts were, in general, quite low, except under sugar beet and following tomato harvest. Areas of diseased beet and high R. solani soil populations that developed in subsequent sugar beet crops did not necessarily coincide with the previously selected diseased areas. High R. solani populations developed from parasitic activity on sugar beet or saprophytically on tomato crop residues. Of the other crops, both maize and soybean may have slightly increased the low R. solani residual populations in soil. The monitoring of R. solani populations in the season prior to, and during the early season of sugar beet cropping did not provide a basis for forecasting disease in fields or sites within fields. The initiation of disease patches in these sugar beet fields was therefore governed by factors other than inoculum density.  相似文献   

13.
Geographical changes in suitability for the cultivation of sugar beet in England and Wales were predicted for climate change scenarios for 2023 and 2065 by integrating a climate database (1951-80) with climate-driven crop growth models. Initially, the outputs were produced as point values (at meteorological site locations) of predicted potential yields for current production. The outputs were validated statistically using actual crop yield figures collated from bibliographic analysis. The most suitable model was run again incorporating projected temperature and precipitation changes for 2023 and 2065. The outputs were mapped using a Geographical Information System and used to predict possible economic changes in farm profitability (and general market trends). Results indicated that the area of suitability for the growth of the crop moves westward with an increase in production in the West Midlands of approximately 5% (2 t ha-1 fresh weight) by 2023 and 13% (6 t ha-1 fresh weight) by 2065. The reduction in production in East Anglia coupled with the increase in production in the West does not align well with the current location of processing factories  相似文献   

14.
A survey of Irish farmers was conducted to identify farmers’ opinions on energy crop production and to characterize potential adopters of energy crop cultivation in Ireland. One hundred and seventy‐two surveys were completed from 25 counties in Ireland. Miscanthus (48%) and grass (30%) were the preferred crops for adoption of energy crop production. Potential adopters described themselves as having a significantly greater level of knowledge of energy crop production compared with other respondents. The results indicate that lack of interest in adopting energy crop production may be due to lack of knowledge regarding the economic benefits of adoption and the variety of energy crops available for cultivation in Ireland. The establishment of long‐term contracts and government schemes were identified as important requirements for the development of bioenergy crop production in Ireland. Energy crop adoption was not limited to farmers undertaking specific farm enterprises. Farmers were motivated to adopt energy crop production for both economic and environmental benefits. These results are the first to provide valuable information on the perspectives of potential adopters of bioenergy crop production in Ireland for the promotion and implementation of a national bioenergy industry. Policy requirements and outreach strategies to encourage adoption of energy crops by agricultural producers are suggested.  相似文献   

15.
16.
Crop raiding around Lake Mburo National Park, Uganda   总被引:1,自引:0,他引:1  
In areas around Lake Mburo National Park, large wild animals wander in close proximity to human settlements. This poses serious conflict in terms of crop damage. The integration of conservation with other land uses is difficult where densely settled agricultural land surrounds a protected area potentially containing problem animals, as is the case for several parks in Africa and Asia. The intensity of crop raiding was quantified through the use of random crop quadrants/plots and area estimation techniques in a portion of raided fields. The animal species concerned were documented from observations, footprints and any other marks left behind. Three variables were tested as predictors of damage: human population density, distance from the park boundary and season. In this study, data is presented regarding crop loss in the different seasons of the year, analysis of crop damage variation and animal species involved in crop loss. A diverse assemblage of animals foraged on subsistence crops and analysis of crop damage revealed significant crop depreciation by wildlife.  相似文献   

17.

Human–primate interfaces are expanding and, despite recent studies on primates from peri-urban environments, little research exists on the impact of agriculture and/or pasture areas on primate social behavior and health. We assessed how crop/pasture areas potentially alter social behavior and health of wild geladas (Theropithecus gelada) frequenting the unprotected area of Kundi (Ethiopia). We predicted that compared to pasture areas, crop areas (i) would be more challenging for geladas (prediction 1) and (ii) would have a greater impact on both aggressive and affiliative behavior, by reducing grooming time and enhancing competition (prediction 2). During January–May 2019 and December 2019–February 2020, we collected data (via scan, focal animal sampling, and video analyses) on direct human disturbance, external signs of pathologies and social behavior of 140 individuals from 14 one-male units and two all-male units. Animals experienced the highest level of human disturbance in crop areas (in line with prediction 1). Individuals from the groups preferentially frequenting crop areas showed the highest prevalence of external signs of pathologies consistent with chemical and biological contamination (alopecia/abnormally swollen parts). We collected 48 fecal samples. Samples from frequent crop users contained the highest rates of parasitic elements/gram (egg/larva/oocyst/cyst) from Entamoeba histolytica/dispar, a parasite common in human settlements of the Amhara region. In crop areas, subjects spent less time grooming but engaged in lower rates of intense aggression (in partial agreement with prediction 2). We speculate that the reduction in social behavior may be a tactic adopted by geladas to minimize the likelihood of detection and maximize food intake while foraging in crops.

  相似文献   

18.
Studies were conducted on eight sugarcane (Saccharum spp. hydrid) cultivars during the 1982–83 (plant crop) and 1983–84 (ratoon crop) growing seasons to determine the effects of glyphosine (Polaris) (N,N-bis (phosphonomethyl) glycine) and glyphosate (Polado) (sodium-N-(phosphonomethyl) glycine) on stalk sucrose content and yield. Difference due to crops (plant vs. ratoon) for sugarcane quality, kilograms of sugar per ton of cane (S/T), sugarcane yield, tons of cane per hectare (TCH), and sugar yield, tons of sugar per hectare (TSH) were significant. Significant differences were found in quality for the ratoon crop and cane and sugar yield in both crops due to ripener treatment. Cultivars in both crops differed significantly in quality and yield. Harvest dates were significantly different for all plant characteristics. Interactions of cultivar by treatment for the plant crop, harvest date by treatment for the ratoon crop, and cultivar by harvest date for both crops for cane quality also were significant. Time from ripener application to achievement of maximum sugar concentration also depended on cultivar. This is important in determining the economic benefits of a ripener treatment. Climatic conditions may also affect the benefits of such applications.  相似文献   

19.
Human–elephant conflict poses a major threat to elephants in many parts of Asia, including Sri Lanka. We studied human–elephant conflict in two areas with contrasting scenarios of landuse and conflict, Kahalle and Yala. Kahalle was developed and settled under the Mahaweli irrigation project and the main agricultural practice was irrigated agriculture, with two annual growing seasons. The area was a mosaic of settlements, agriculture, and small forest patches with ill defined human- and elephant-use areas. Elephants ranged within the habitat mosaic year round, occupying remnant forest patches and raiding adjacent crops at night. In contrast, Yala was dominated by a large protected area complex, and the main agricultural methods were slash-and-burn agriculture and rain-fed paddy cultivation. Human- and elephant-use areas were well defined and segregated. The protected area provided elephants with a refuge and food during the rainy season, when the single annual crop was grown. During the dry season, elephants moved into slash-and-burn areas and utilized leftover crops and pioneer vegetation in fallow fields. The landuse pattern and agricultural practices in Yala facilitated co-existence, whereas that in Kahalle led to year round conflict. We suggest that areas managed according to traditional landuse practices should be part of an elephant conservation strategy, where people and elephants have to share resources.  相似文献   

20.
Crop Expansion and Conservation Priorities in Tropical Countries   总被引:1,自引:0,他引:1  
Expansion of cropland in tropical countries is one of the principal causes of biodiversity loss, and threatens to undermine progress towards meeting the Aichi Biodiversity Targets. To understand this threat better, we analysed data on crop distribution and expansion in 128 tropical countries, assessed changes in area of the main crops and mapped overlaps between conservation priorities and cultivation potential. Rice was the single crop grown over the largest area, especially in tropical forest biomes. Cropland in tropical countries expanded by c. 48,000 km2 per year from 1999–2008. The countries which added the greatest area of new cropland were Nigeria, Indonesia, Ethiopia, Sudan and Brazil. Soybeans and maize are the crops which expanded most in absolute area. Other crops with large increases included rice, sorghum, oil palm, beans, sugar cane, cow peas, wheat and cassava. Areas of high cultivation potential—while bearing in mind that political and socio-economic conditions can be as influential as biophysical ones—may be vulnerable to conversion in the future. These include some priority areas for biodiversity conservation in tropical countries (e.g., Frontier Forests and High Biodiversity Wilderness Areas), which have previously been identified as having ‘low vulnerability’, in particular in central Africa and northern Australia. There are also many other smaller areas which are important for biodiversity and which have high cultivation potential (e.g., in the fringes of the Amazon basin, in the Paraguayan Chaco, and in the savanna woodlands of the Sahel and East Africa). We highlight the urgent need for more effective sustainability standards and policies addressing both production and consumption of tropical commodities, including robust land-use planning in agricultural frontiers, establishment of new protected areas or REDD+ projects in places agriculture has not yet reached, and reduction or elimination of incentives for land-demanding bioenergy feedstocks.  相似文献   

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