Adaptive cluster sampling for estimation of deforestation rates   总被引：2，自引：0，他引：2  

Steen?MagnussenEmail author  Werner?Kurz  Don?G.?Leckie  Dennis?Paradine 《European Journal of Forest Research》2005,124(3):207-220

National estimates of deforestation rates may be based on a survey. Precise estimation requires an efficient design. When deforestation rates are low (<1%) large sample sizes are required with traditional sampling designs to meet a precision target. This study explores the efficiency of adaptive cluster sampling (ACS) for this estimation problem. The efficiency is assessed by simulated ACS sampling from 18,200 × 200 km populations with 78–10,742 deforestation polygons (DFP) of different shape and size and average 10-year deforestation rates between 0.2% and 1.0%. Each population is composed of four million square 1 ha population units (PU) in a regular grid. Relative root mean square errors (RMSE) of ACS were, depending on sample size, 30–50% lower than comparable errors with simple random sampling (SRS) designs. ACS achieves this advantage by adaptively adding PUs to an initial SRS sample of size n. Realized ACS sample sizes were, on average, twice the nominal size (n). Three measures of ACS efficiency indicated that the costs of adaptively increasing the sample size are critical for the effectiveness of ACS. Population effects were manifest in all estimators. Estimates of the abundance, size, and shape of DFPs will allow a prediction of these effects. Populations dominated by a few large DFPs were clearly unsuited for ACS. The performance of ACS relative to that of SRS was similar across plot sizes of 1, 10, and 40 ha. The general conclusion of this study is that the lower RMSE of ACS remains attractive when the average cost of adaptively adding a PU to the initial sample is low relative to the average cost of sampling a PU at random.  相似文献   

Genetic and environmental effects on chromosome doubling of sugarbeet (Beta vulgaris L.) haploids     

M. Ragot  P. Steen 《Euphytica》1992,63(3):233-237

Summary Chromosome doubling has been a limiting factor for production of doubled-haploids, a means of obtaining fruly homozygous individuals, and a time-saving alternative to repeated selfing for the creation of inbred lines. The existence of genetic, environmental and genotype × environment interaction effects on chromosome doubling ability of sugarbeet (Beta vulgaris L.) haploids was investigated. Haploids were derived from four distinct, highly heterozygous diploid populations through in vitro culture of unpollinated ovules. Ovule-derived plants were treated with colchicine to double their chromosome complement. Environmental effects were determined from replication of the experiment at seven dates. Both genetic and environmental factors were found to affect chromosome doubling ability of sugarbeet haploids. No significant interaction between genotype and environment was identified. The presence of genetic effects on chromosome doubling ability is discussed with regard to its implications on breeding programs.  相似文献   

Effects of sewage sludge stabilization on fertilizer value and greenhouse gas emissions after soil application     

Hiroko Yoshida  Martin P. Nielsen  Charlotte Scheutz  Lars S. Jensen  Thomas H. Christensen  Steen Nielsen 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(6):506-516

Application of sewage sludge on agricultural land becomes more and more common in many parts of the world in order to recycle the nutrients from the sludge. A range of sewage sludge stabilization techniques are available to make the sludge more stable prior to storage, transportation, and application. These stabilization techniques include dewatering, drying, anaerobic digestion, composting, and reed bed sludge treatment. However, very few studies have investigated the effect of these techniques after the sludge has been applied to agricultural land. The objective of the current study was therefore to investigate the effect of sewage sludge stabilization techniques on the C and N mineralization and gaseous emissions from soil. A soil incubation was conducted to determine the rate of C and N mineralization and N₂O and CH₄ emissions of sewage sludge stabilized using different techniques. Unstabilized sludge released up to 90% of their C content as CO₂, part of which could be caused by release of CO₂ from carbonates. Compared with this, sludge stabilization including anaerobic digestion and drying resulted in a reduction of the C mineralization rate of about 40%. Liming reduced C mineralization with around 29%, while treatment in a reed bed system reduced it by 74%. The current study thus clearly demonstrated that stabilization techniques resulted in sludge that was more stable once they were applied to agricultural land. Stabilization also reduced the N immobilization phase, potentially improving the value of the sludge as a fertilizer. Emissions of CH₄ were also reduced through sludge stabilization and mainly occurred after application of easily degradable sludge types, which is likely to have enhanced the creation of anaerobic microsites. The stabilization processes also decreased emissions of N₂O. The results for both CH₄ and N₂O indicate that the stabilization tends to reduce the chance of developing conditions where these gases could be produced.  相似文献   

Factors affecting the concentration of Zn,Fe and Mn in herbage from organic farms and in relation to dietary requirements of ruminants     

Espen Govasmark  Arvid Steen  Anne Kjersti Bakken  Turid Strøm  Sissel Hansen 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):131-142

To obtain a general picture of the herbage zinc, iron and manganese concentrations and their relation to dietary requirements of ruminants on organic farms, we analysed soil and herbage samples from four regions in Norway. The soil median Zn, Fe and Mn concentrations were 0.18, 13 and 0.84 mg/L, respectively. The herbage median (10th–90th percentile) Zn, Fe and Mn concentrations (mg/kg) in herbage in the first cut were 19 (14–34), 50 (36–88), 34 (22–86) and in the second cut 21 (16–37), 84 (52–171) and 66 (36–205), respectively. The results of mixed model analysis of herbage Zn, Fe and Mn indicate that soil pH, soil texture, soil mineral concentration and botanical composition are the most influencing factors. We conclude that Zn, Fe and Mn did not limit plant growth, and that the herbage concentrations, except for Zn, were sufficient to meet the dietary needs of ruminants on organic dairy farms.  相似文献   

Risk factors for Coxiella burnetii antibodies in bulk tank milk from Danish dairy herds     

Jens Frederik Agger  Suman Paul  Anna-Bodil Christoffersen  J?rgen Steen Agerholm 《Acta veterinaria Scandinavica》2013,55(1):80

The aim was to identify risk factors associated with Coxiella burnetii antibody positivity in bulk tank milk (BTM) samples from 100 randomly selected Danish dairy cattle herds. Antibody levels were measured by an enzyme-linked immuno-sorbent assay. Before testing the herds, the farm managers were interviewed about hired labour, biosecurity, housing and herd health during the 12 months prior to the study. Variables considered important for C. burnetii antibody positivity in multivariable logistic regression analysis included the sharing of machines between farms (OR = 3.6), human contacts (OR = 4.2), artificial insemination by other people than artificial insemination technicians (OR = 7.7), routine herd health contract with the veterinarian (OR = 4.3) and hygiene precautions taken by veterinarians (OR = 5). In addition, herd size, hired labour, trading of cattle between farms, quarantine and use of calving and disease pens also showed significant association in univariable analysis. This study demonstrates that strict biosecurity is important for the prevention of infections with C. burnetii.  相似文献   

Processes affecting genetic structure and conservation: a case study of wild and cultivated <Emphasis Type="Italic">Brassica rapa</Emphasis>     

Naja Steen Andersen  Gert Poulsen  Bente Anni Andersen  Lars Pødenphant Kiær  Tina D’Hertefeldt  Mike J. Wilkinson  Rikke Bagger Jørgensen 《Genetic Resources and Crop Evolution》2009,56(2):189-200

When planning optimal conservation strategies for wild and cultivated types of a plant species, a number of influencing biological and environmental factors should be considered from the outset. In the present study Brassica rapa was used to illustrate this: to develop Scandinavian conservation strategies for wild and cultivated B. rapa, DNA-marker analysis was performed on 15 cultivated and 17 wild accessions of B. rapa plus 8 accessions of the cross compatible B. napus. The B. rapa cultivars were bred in Sweden and Finland in 1944–1997 and the wild B. rapa material was collected from Denmark, Sweden and United Kingdom. The B. napus accessions were bred within the last 20 years in the Scandinavian countries. Results were based on scoring of 131 polymorphic ISSR markers in the total plant material. A Bayesian Markov chain Monte Carlo (MCMC) approach implemented in NewHybrids demonstrated a clear distinction of B. rapa and B. napus individuals except for three individuals that seemed to be backcrosses. The backcrossed hybrids descended from two Swedish populations, one wild and one escaped. The overall pattern of genetic variation and structure in B. rapa showed that cultivated and wild B. rapa accessions formed two almost separated clusters. Geographical origin and breeding history of cultivars were reflected in these genetic relationships. In addition, wild populations from Denmark and Sweden seemed to be closely related, except for a Swedish population, which seemingly was an escaped cultivar. The study point to that many processes, e.g. spontaneous introgression, naturalisation, breeding and agricultural practise affected the genetic structure of wild and cultivated B. rapa populations.  相似文献   

Stand-level wind damage can be assessed using diachronic photogrammetric canopy height models     

Jean-Pierre Renaud  Cédric Vega  Sylvie Durrieu  Jonathan Lisein  Steen Magnussen  Philippe Lejeune  Mériem Fournier 《Annals of Forest Science》2017,74(4):74

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Intracytoplasmic inclusion bodies associated with vesicular, ulcerative and necrotizing lesions of the digestive mucosa of a roedeer (Capreolus capreolus L.) and a moose (Alces alces L.)     

R. Feinstein  C. Rehbinder  E. Rivera  T. Nikkil  M. Steen 《Acta veterinaria Scandinavica》1987,28(2):197-200

At post-mortem examination of a roedeer and a moose, ulcerative and necrotizing lesions were observed in the digestive mucosa.Both animals were serologically positive for Bovine Viral Diarrhea Virus antibodies. Histological examination revealed intra- and intercellular oedema in stratum germinativum and spinosum, formation of vesicles and ulcers, and intracytoplasmic inclusion bodies in numerous epithelial cells of mainly stratum germinativum.Electronmicroscopy confirmed the histological findings and demonstrated inclusion bodies containing a granular electron dense material encircled by a single-layer membrane. Virus particles were not found.  相似文献   

The Use of Tumor Doubling Time in Veterinary Clinical Oncology1     

Steen Bech-Nielsen  John S. Reif  Robert S. Brodey 《Veterinary radiology & ultrasound》1976,17(3):113-116

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The implication of maternal effects for genetic improvement of litter size in pigs     

H.A.M. Van Der Steen 《Livestock Production Science》1985,13(2):159-168

Gilts raised in large litters produce smaller litters than those raised in small litters. These maternal influences affect the regression coefficient of additive genetic on phenotypic value. Over a range of plausible values, this regression coefficient, and thus genetic change, decreased 5–10% due to maternal effects. So the genetic impact of maternal effects on litter size is minimal. In a selection experiment, selected breeding gilts are raised in large litters. This results in a negative maternal influence on litter size which is mainly environmental. This influence can be eliminated to a large extent by standardization of those litters from which gilts are going to be selected. Selection for fertility seems to be possible if the requirements (accurate correction for fixed effects, optimization of herd management, high selection intensity, standardization of litters and accurate estimation of breeding values) are fulfilled.  相似文献