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1.
Vegetation structure and composition during the pre‐ and early‐European period in Australia is often proposed as a benchmark against which to measure the effects of modern landscape management practices. However, little quantifiable information exists for that historical period. One potential source of information is the land survey record, used in this study to provide estimates of tree densities that existed during the period 1870 to 1900 in part of central New South Wales. Estimates were obtained for 23 parishes in the north Lachlan River valley, between the towns of Condobolin and Tottenham. Densities were calculated from portion corner to nearest tree data obtained from historical survey plans, using the plotless, closest individual method. Densities ranged from 6.0 to 31.4 trees per hectare for parishes with enough data points for reliable calculation. These figures would account for trees of a diameter large enough to be blazed with a survey mark. Any smaller trees would be additional and, although no quantitative data existed for this, qualitative evidence suggested that the figures obtained were more likely to be underestimates due to the presence of such small trees. The study area was predominantly covered by woodlands which varied in density across the landscape, in comparison to the modern landscape where much of the native vegetation has been cleared for agriculture. Although the tree density figures should be considered to be indicative rather than precise, they provide quantifiable historical figures for past conditions in an area where the historical record is otherwise sparse. Such information is valuable for interpreting ecological changes brought about by modern land management.  相似文献   

2.
Abstract

This paper presents inferences based on the results of an experimental project comparing the effectiveness of stone, bronze, and steel axes in felling trees. The study shows that bronze is as efficient as steel for this task, and therefore the two material types can be considered equivalent when comparing technologies. We support the findings of other studies indicating that metal axes are more efficient than stone axes in a number of ways other than effort expended. Other variables that affect tree felling efficiency are discussed. Tree type, tree diameter, and axe type are the most important, but other factors may also be significant. The use of regionally specific estimates for tree felling time is suggested when making cultural inferences based upon experimental data.  相似文献   

3.
We propose a new estimator of spatial autocorrelation of areal incidence or prevalence rates in small areas, such as crime and health indicators, for correcting spatially heterogeneous sampling errors in denominator data. The approach is dubbed the heteroscedasticity‐consistent empirical Bayes (HC‐EB) method. As American Community Survey (ACS) data have been released to the public for small census geographies, small‐area estimates now form the demographic landscape of neighborhoods. Meanwhile, there is growing awareness of the diminished statistical validity of global and local Moran’s I when such small‐area estimates are used in denominator data. Using teen birth rates by census tracts in Mecklenburg County, North Carolina, we present comparisons of conventional and new HC‐EB estimates of Global and Local Moran’s I statistics created on ACS data, along with estimates on ground truth values from the 2010 decennial census. Results show that the new adjustment method dramatically enhances the statistical validity of global and local spatial autocorrelation statistics.  相似文献   

4.
Rural landlessness and pauperisation are ongoing processes in Bangladesh, forcing people to migrate to other areas or countries in search of a livelihood. The study estimates levels of and differentials in out-migration of adult Bangladeshis, and examines reasons for migration and place of destination, using longitudinally collected migration data in the International Centre for Diarrhoeal Disease Research, Bangladesh's (ICDDR,B's) Matlab surveillance area during the periods 1997–1999 and 2006–2008. The out-migration rate increased over time (48 per cent men versus 28 per cent women). Men migrated primarily for economic reasons (73–76 per cent), and women, for familial reasons (77–78 per cent). The younger, educated and well-off were more likely to migrate to urban areas and foreign countries than their older, less educated and poorer peers, who were more likely to migrate to other rural areas. Effective steps are needed to check rural-urban migration, and its numerous adverse consequences.  相似文献   

5.
This paper explores the concepts of old‐growth forests, preservation and natural disturbance and demonstrates how contemporary biogeographic theory contributes to successful preservation of old‐growth forests. The case study analyzes the composition, structure, age and growth histories of trees in Big Timber Park, Whistler, British Columbia. Composition. The structure of the forest was diverse and tree ages ranged from 122 to 305 years. The densities of large old Douglas‐fir, shade‐tolerant trees and all snags are indicative of old‐growth forests; however, maximum tree diameters and densities of large snags and logs do not meet quantitative criteria for old‐growth forests. The abundance of tree regeneration and understory vegetation are relatively low. We conclude that some aspects of Big Timber Park are transitional between the mature and old‐growth stages of forest development. In the future, fine‐scale canopy gaps caused by tree senescence and interactions among insects, pathogens and wind are expected to dominate stand dynamics. Forest structure will become increasingly complex, exemplifying the dynamic nature of old‐growth forests. To successfully preserve Big Timber Park and La préservation des forêts other old‐growth forests in Canada requires understanding of natural disturbances. Preservation and the criteria and indicators used to measure successful preservation must explicitly include elements of natural change.  相似文献   

6.
The article analyses the long-term changes in the spatial distribution and density of the urban settlements in Rome (Italy), a compact Mediterranean city recently undergoing low- and medium-density expansion. Eight density classes were considered: no buildings, <0.5 buildings per hectare, 0.5–1.0, 1–2, 2–3, 3–5, 5–10, >10 buildings per hectare. Non-urbanized land amounted to 89% of the investigated area in 1919 and fell to 30% in 2001. Building density increased over time suggesting that both concentration and diffusion processes occurred in the study area. During 1919–2001, the building density was stable in only 37% of the investigated land. In that period, the largest part of the area (47%) underwent a low increase in building density, while 12% of the area passed from a low-density to a high-density class. Settlement density decreased rapidly with the distance from the city centre in 1919 and 1945, while a marked increase was observed in areas progressively further away from Rome since 1961. In recent years, land consumption was partly determined by the planning strategies adopted by Rome's municipality with the aim of producing a more balanced and polycentric region. More effective policies preserving the quality of the environment and promoting the sustainable development of peri-urban Mediterranean regions are needed.  相似文献   

7.
The census is the traditional source of population figures at various levels. Census figures however are technically outdated immediately they are released because planners require figures for the present and possibly for future dates. In an attempt to meet this demand different organisations and researchers produce population estimates and projections. These estimates however are usually at higher geographical levels and often do not meet the planning needs of administrators at lower geographical levels. This study extends a top‐down estimation method to an African country by estimating the mid‐2014 population at ward level in South Africa. The study used the 2011 South Africa Census to estimate current levels of fertility, mortality as well as current trends in net migration at a higher geographical level. Historical trends in fertility and mortality were based on the 1996 Census, 1997 and 1998 October Household Surveys as well as the 2007 Community Survey data. The results indicate that that 20 of the largest wards as at mid‐2014 were located in South Africa's metropolitan areas. Nineteen of the 20 largest wards are currently growing at a rate of over 4% per annum and if this trend continues, eighteen of these wards will double their current population size in less than 15 years.  相似文献   

8.
In this paper I use bootstrap procedures to develop confidence intervals for estimates of total industrial output generated per thousand tourist visits. Mean expenditures from replicated visitor expenditure data included weights to correct for response bias. Impacts were estimated with IMPLAN. Ninety percent interval endpoints were 6 to 16 percent above or below the original sample's point estimate depending on the calculation method. Due to the linearity of input-output a shortcut method that estimates confidence interval endpoints from the distribution of mean expenditure profiles yields nearly identical results.  相似文献   

9.
ABSTRACT A single-equation econometric approach is developed for estimating personal income on a quarterly basis for counties and county aggregates (e.g., metropolitan areas). An experiment is conducted on state data to test the accuracy of the estimates. The experiment indicates that they would be highly accurate for large local areas; for local areas comprising at least 20 percent of their state's total personal income, the estimates would fall within 2 percent of BEA-type estimates 95 percent of the time. An aggregate estimation approach is shown to be preferable to a component approach. Using data on local department store sales, the quarterly personal income estimates are shown to forecast better than the currently available annual estimates.  相似文献   

10.
The study of tree rings has been used for over 100 years to inform climatic and geomorphological reconstructions. In mainland Australia, no tree species are currently recognised as providing reliable sources for such studies over extensive areas. Eucalyptus camaldulensis is a widely growing species with a growth pattern that is closely linked to high levels of available moisture, such as that associated with floods. The species therefore has the potential to provide palaeoclimatic information that may be of use in hydrological and geomorphological studies. This study initially examines the microstructure of samples of E. camaldulensis taken from the Barmah Forest to assess the applicability of the species to dendroecological investigation. It is found that samples of the species exhibit ring‐like structures, although there are areas of the samples that contain zones of growth without clear ring boundaries. The patterns of growth rings and zones are found to be common to many trees at a site, although the level of variability of pattern from tree to tree is high. Options for future development of the approach described here are to combine ring studies with isotopic‐based analysis to provide a combination of tree age and climatic history.  相似文献   

11.
This paper estimates China’s future population and labour force by developing a novel forecasting model for population. It combines information about age-specific parameters on fertility and mortality for both rural and urban areas using information about rural–urban migration and the transformation of rural areas into urban ones. This model takes into account the effects of urbanisation on changes in the age structure of the Chinese population; and provides separate projections on the rural and urban populations. Our findings show that (i) the shares of people aged 65 and over, in China’s rural and urban populations, will double between 2010 and 2030; this implies that the ageing problem in rural areas will continue to be more serious than in urban areas; (ii) the rural labour force will shrink by 45 per cent, between 2010 and 2030, while the urban labour force will grow by 34 per cent; and (iii) China’s urbanisation rate will increase to 71 per cent by 2030.  相似文献   

12.
Honey from the giant Asian honey bee (Apis dorsata) has been harvested by communities throughout Southeast Asia for centuries. In Indonesia, 80 per cent of the national supply of honey comes from Sumbawa; however, there is limited information regarding the sustainability and importance of honey hunting in supporting rural livelihoods. This study used semi‐structured interviews and questionnaires to examine honey hunting and forest honey production in Sumbawa. It evaluates the economic and cultural importance, opportunities, and constraints of honey hunting and prompts us to suggest that income generation from honey plays a critical role in supporting rural communities. Of respondents, 83 per cent reported that income from honey was essential and accounts for 68 per cent of cash income. Yet honey hunters were harvesting using destructive methods under dangerous conditions and are subject to unpredictable market prices and fluctuating yields. Unlike situations in other areas of Indonesia, no system of customary law was found to exist that defines ownership of honey trees and the right to harvest from them. Limited access to market information, high moisture content of honey, and limited training and extension services were identified as key constraints. Future research exploring the sustainability of harvesting practices and mechanisms for improving profitability of honey hunters would be valuable.  相似文献   

13.
Core sampling is normally used for dendrochronological age determination of both timber and living trees. As core sampling can seriously damage artefacts, a photographic method was tried on 29 wooden objects made of Scots pine (Pinus sylvestris L.). These were photographed and tree‐ring sequences for dendrochronological analysis were measured on the photographs in the laboratory. Nine objects could be dated. The undatable objects had few tree‐rings or a non‐matching tree‐ring pattern. The region in Norway where the material had grown could be determined by matching against various regional chronologies.  相似文献   

14.
Discrete choice models are commonly used to predict individuals' activity and travel choices either separately or simultaneously in activity‐scheduling models. This paper investigates the possibilities of decision tree induction systems as an alternative approach. The ability of decision trees to represent heuristic decision rules is evaluated and a method of capturing interactions across decisions in a sequential decision model is outlined. Decision tree induction algorithms, such as C4.5, CART, and CHAID, are suited to derive the decision rules from empirical data. A case study to illustrate the approach considers decisions of individuals when they are faced with the choice to combine different out‐of‐home activities into a multipurpose, multistop trip or make a trip for each activity separately. Data from a large‐scale activity diary survey are used to induce the decision rules. Possible directions of future research are identified.  相似文献   

15.
"小白礁I号"清代沉船遗址位于浙江省宁波市象山县石浦镇东南约26海里的渔山列岛海域,于2008年首次发现,计划于2014年将沉船船体发掘出水。为了从多方面了解"小白礁I号"沉船的特点,考察其建造地点及造船工艺方面的有关问题,制定出水船体保护方案,为此,分别从龙骨、肋骨、隔舱板、船底板等多个部位对船体木材采样进行了种属鉴定。种属鉴定结果表明,"小白礁I号"沉船船体所用木材多为龙脑香科、马鞭草科和山榄科等阔叶硬材,且多产于东南亚热带地区而在我国较少分布,有别于我国以往考古发现的古船。"小白礁I号"沉船用材及保存状况的了解为船体发掘出水后的保护修复工作创造了非常有利的条件。  相似文献   

16.
This article comments upon the situation of sprawl in Spain and Madrid, especially residential sprawl. It does not appear to be a serious problem due to its low starting point, but artificial surface and residential sprawl is growing rapidly. For that reason, it may be an issue in the future. Between 2000 and 2006, urban residential land use grew 0.4% in Spain and 0.2% in Europe per year, land use of industrial and commercial areas grew 2.3% in Spain and 0.4% in Europe and total artificial surface grew 2.7% in Spain and 0.6% in Europe (EEA, 2010). Further, we will study the legislation on maximum and minimum urban density in Spain. The highest maximum urban density is established by the Basque Country, with 230 dwellings per hectare, and the highest minimum urban density is established by Catalonia, with 50 dwellings per hectare. In both cases, it is applied to only certain types of territories. Finally, we will analyse what happens in the Region of Madrid in relation to sprawl. It has very similar patterns compared with the rest of Spain, although more pronounced.  相似文献   

17.
Spatial clusters contain biases and artifacts, whether they are defined via statistical algorithms or via expert judgment. Graph-based partitioning of spatial data and associated heuristics gained popularity due to their scalability but can define suboptimal regions due to algorithmic biases such as chaining. Despite the broad literature on deterministic regionalization methods, approaches that quantify regionalization probability are sparse. In this article, we propose a local method to quantify regionalization probabilities for regions defined via graph-based cuts and expert-defined regions. We conceptualize spatial regions as consisting of two types of spatial elements: core and swing. We define three distinct types of regionalization biases that occur in graph-based methods and showcase the use of the proposed method to capture these types of biases. Additionally, we propose an efficient solution to the probabilistic graph-based regionalization problem via performing optimal tree cuts along random spanning trees within an evidence accumulation framework. We perform statistical tests on synthetic data to assess resulting probability maps for varying distinctness of underlying regions and regionalization parameters. Lastly, we showcase the application of our method to define probabilistic ecoregions using climatic and remotely sensed vegetation indicators and apply our method to assign probabilities to the expert-defined Bailey's ecoregions.  相似文献   

18.
This article presents a method for investigating the spatial distribution of vehicle and pedestrian traffic crashes relative to the volume of vehicle and pedestrian movement in urban areas. This method consists of two phases. First, vehicle and pedestrian traffic volumes on the street network are modeled using a space syntax configurational analysis of the network, land use data, and observed traffic data. Second, crash prediction models are fitted to the traffic crash data, using negative binomial regression models and based on traffic volume estimates and street segment lengths. The method was applied in two areas in Tel Aviv, Israel, which differ in their morphological and traffic characteristics. The case‐studies illustrated the method's capability in identifying hazardous locations on the network and examining relative crash risks. The analysis shows that an increase in vehicle or pedestrian traffic volume tends to be associated with a decrease in relative crash risk. Moreover, the spatial patterns of relative crash risks are associated with the design characteristics of urban space: areas characterized by dense street networks encourage more walking, and are generally safer for pedestrians, while those with longer street segments encourage more driving, are less safe for pedestrians, but safer for vehicles.  相似文献   

19.
Archaeological and historical data, combined with GIS analysis gives us new perspectives on 11th c. medieval period envoy missions from the Song Dynasty (960–1279) to the Liao Empire (907–1125) Middle Capital in Chifeng Inner Mongolia, China. The envoys’ routes can be recreated on maps, and optimal route and viewshed analyses give us insight into the Liao’s concerns about these foreign missions crossing their territory and how they addressed them. Furthermore, population estimates can be made from envoy information that can be used to extrapolate population density estimates from archaeological data for other areas in Chifeng.  相似文献   

20.
Public policy has often addressed the problems of water supply and sanitation from the supply side to the neglect of demand side aspects in developing countries like India. This policy has not only rendered a large number of projects financially unviable but has also resulted in inadequate coverage of aspects such as population and ecological unsustainability. This article, based on household level information from six villages in a water scarce region of India (Rajasthan state), examines inter- and intra-village variations in water use and the costs, direct and indirect, involved in obtaining water. It also estimates households' willingness and ability to pay for water, using the contingent valuation method (CVM). Using qualitative as well as quantitative methods, it is argued that it is the failure of government policy and of institutions which has led to severe water shortages in harsh environments rather than supply or financial bottlenecks per se. While the estimates of price elasticity of water use indicate the feasibility of water pricing in the rural areas, the willingness to pay estimates question the general assumption that rural households are willing to pay 5 per cent of their income/expenditure for water. Various economic and extra economic factors such as household income, low opportunity costs of women and children, and attitudes towards female labour and public goods are vital in influencing the households' willingness to pay for water.  相似文献   

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