Operational efficiency of ballast water biocides at low water temperatures
Kaag, N.H.B.M. ; Sneekes, A.C. - \ 2015
Den Helder : IMARES (Report / IMARES Wageningen UR C052/15) - 22
transport over water - schepen - waterballast - geïntroduceerde soorten - waterzuivering - oceanen - canada - water transport - ships - water ballasting - introduced species - water treatment - oceans
In the period 2013-2015 the effect of two biocides used for the treatment of ballast water has been evaluated at low ambient temperatures. Peraclean® Ocean and sodium hypochlorite were used as biocides. Most of the tests were conducted during winter and early spring at the laboratories of IMARES in Den Helder, using outdoor cultures from which phytoplankton and zooplankton (as communities) were collected for the tests. In summer 2013, tests were also conducted at Svalbard in the Arctic using natural zooplankton. Here only Peraclean® Ocean was tested.
Application of a visual soil examination and evaluation technique at site and farm level
Sonneveld, M.P.W. ; Heuvelink, G.B.M. ; Moolenaar, S.W. - \ 2014
Soil Use and Management 30 (2014)2. - ISSN 0266-0032 - p. 263 - 271.
environmental-impact - indicators - quality - agriculture - framework - canada - field
Visual soil examination and evaluation (VSEE) techniques are semi-quantitative methods that provide rapid and cost-effective information on soil quality. These are mostly applied at site or field level, but there is an increased need for soil quality indicators at farm level to allow integration with other sustainability indicators. The objectives of this study were to develop and apply a protocol for application of a VSEE technique at site level, to assess the VSEE observations against standardized laboratory analyses and to aggregate VSEE observations to farm level using an appropriate sampling design. The study was conducted at ten dairy farms in a reclaimed polder in the Netherlands with clay and organic soils. A stratified random sampling design was used to account for spatial variability in land use and soil series. VSEE was carried out using the Visual Soil Assessment approach. Results show that 81% of sites were assessed as good and the remainder as moderate to poor. For the clay soils, field observations of soil structure were significantly correlated with pH, bulk density, soil organic matter (SOM) and mean weight diameter of aggregates, whereas for organic soils, soil structure significantly correlated with pH, bulk density, organic C and SOM. The range in overall scores calculated at farm level was smaller than at site level, and most farms were assessed as good.
The El Niño Southern Oscillation index and wildfire prediction in British Columbia
Xu, Zhen ; Kooten, G.C. van - \ 2014
Forestry Chronicle 90 (2014)5. - ISSN 0015-7546 - p. 592 - 598.
inflated poisson regression - wildland fire - forest-fires - united-states - climate - canada - model - weather
This study investigates the potential to predict monthly wildfires and area burned in British Columbia's interior using El Niño Southern Oscillation (ENSO). The zero-inflated negative binomial (ZINB) and the generalized Pareto (GP) distributions are used, respectively, to account for uncertainty in wildfire frequency and area burned. Results indicate that a four-month lag of the ENSO index has a strong positive influence on monthly wildfire occurrence. Upon fitting the GP distribution with a logit model regressed on the ENSO index, we predict the probabilities that monthly area burned exceeds 1700 ha and find that risks of large fires are significantly higher in northwestern BC. However, the ENSO is likely unable to provide consistent predictions of the total area burned in any month. Sensitivity analysis indicates that increases in the mean value of the monthly ENSO index result in a small increase in the predicted number of fires and an increase in the probability of large burns. This study has several implications for decision-making regarding firefighting budget planning and insurance for firefighting expenditures.
Wetlands Retention and Optimal Management of Waterfowl Habitat under Climate Change
Withey, P. ; Kooten, G.C. van - \ 2014
Journal of Agricultural and Resource Economics 39 (2014)1. - ISSN 1068-5502 - p. 1 - 18.
northern prairie wetlands - us - metaanalysis - temperature - impacts - canada - yields
We develop a positive mathematical programming model to investigate the impact of climate change on land use in the prairie pothole region of western Canada, with particular focus on wetlands retention. We examine the effect of climate change and biofuel policies that are implemented to mitigate climate change on wetlands retention. Simulation results indicate that a drier climate could decrease wetlands by as much as 38% if the externality benefits of wetlands are considered, but by nearly 80% if they are not. Reductions in wetlands are most pronounced in the south-central areas of the region.
Avian influenza trasnmission risks: analysis of biosecuritiy measures and contact structure in Dutch poultry farming
Ssematimba, A. ; Hagenaars, T.H.J. ; Wit, J.J. de; Ruiterkamp, F. ; Fabri, T.H.F. ; Stegeman, J.A. ; Jong, M.C.M. de - \ 2013
Preventive Veterinary Medicine 109 (2013)1-2. - ISSN 0167-5877 - p. 106 - 115.
potential pathways - virus h7n7 - a viruses - netherlands - epidemic - chickens - georgia - canada - japan
In the 2003 epidemic of highly pathogenic avian influenza in Dutch poultry, between-farm virus transmission continued for considerable time despite control measures. Gaining more insight into the mechanisms of this spread is necessary for the possible development of better control strategies. We carried out an in-depth interview study aiming to systematically explore all the poultry production activities to identify the activities that could potentially be related to virus introduction and transmission. One of the between-farm contact risks that were identified is the movement of birds between farms during thinning with violations of on-farm biosecurity protocols. In addition, several other risky management practices, risky visitor behaviours and biosecurity breaches were identified. They include human and fomite contacts that occurred without observing biosecurity protocols, poor waste management practices, presence of other animal species on poultry farms, and poor biosecurity against risks from farm neighbourhood activities. Among the detailed practices identified, taking cell phones and jewellery into poultry houses, not observing shower-in protocols and the exchange of unclean farm equipment were common. Also, sometimes certain protocols or biosecurity facilities were lacking. We also asked the interviewed farmers about their perception of transmission risks and found that they had divergent opinions about the visitor- and neighbourhood-associated risks. We performed a qualitative assessment of contact risks (as transmission pathways) based on contact type, corresponding biosecurity practices, and contact frequency. This assessment suggests that the most risky contact types are bird movements during thinning and restocking, most human movements accessing poultry houses and proximity to other poultry farms. The overall risk posed by persons and equipment accessing storage rooms and the premises-only contacts was considered to be medium. Most of the exposure risks are considered to be similar for layer and broiler farms. Our results, including those on farmer opinions, are relevant for the communication with farmers and poultry-related businesses about practices and risks. We conclude by providing recommendations for improvement of control strategies.
Forest inventory stand height estimates from very high spatial resolution satellite imagery calibrated with lidar plots
Mora, B. ; Wulder, M.A. ; Hobart, G.W. ; White, J.C. ; Bater, C.W. ; Gougeon, F.A. ; Varhola, A. ; Coops, N.C. - \ 2013
International Journal of Remote Sensing 34 (2013)12. - ISSN 0143-1161 - p. 4406 - 4424.
airborne scanning laser - tree height - canopy height - stem volume - large-area - integration - landsat - canada - segmentation - update
Many areas of forest across northern Canada are challenging to monitor on a regular basis as a result of their large extent and remoteness. Although no forest inventory data typically exist for these northern areas, detailed and timely forest information for these areas is required to support national and international reporting obligations. We developed and tested a sample-based approach that could be used to estimate forest stand height in these remote forests using panchromatic Very High Spatial Resolution (VHSR, <1 m) optical imagery and light detection and ranging (lidar) data. Using a study area in central British Columbia, Canada, to test our approach, we compared four different methods for estimating stand height using stand-level and crown-level metrics generated from the VHSR imagery. 'Lidar plots' (voxel-based samples of lidar data) are used for calibration and validation of the VHSR-based stand height estimates, similar to the way that field plots are used to calibrate photogrammetric estimates of stand height in a conventional forest inventory or to make empirical attribute estimates from multispectral digital remotely sensed data. A k-nearest neighbours (k-NN) method provided the best estimate of mean stand height (R-2 = 0.69; RMSE = 2.3 m, RMSE normalized by the mean value of the estimates (RMSE-%) = 21) compared with linear regression, random forests, and regression tree methods. The approach presented herein demonstrates the potential of VHSR panchromatic imagery and lidar to provide robust and representative estimates of stand height in remote forest areas where conventional forest inventory approaches are either too costly or are not logistically feasible. While further evaluation of the methods is required to generalize these results over Canada to provide robust and representative estimation, VHSR and lidar data provide an opportunity for monitoring in areas for which there is no detailed forest inventory information available.
|Ervaringen over onderzoeksamenwerking gedeeld (interview met Marloes Kraan)
Kraan, M.L. - \ 2013
Visserijnieuws 33 (2013)22. - ISSN 1380-5061 - p. 6 - 7.
visserij - verspreiding van onderzoek - kennisoverdracht - europa - canada - fisheries - diffusion of research - knowledge transfer - europe - canada
De Nederlandse vissers Johan Baaij (TH 10) rn Rene Sperling (OD 6) brachten in mei 2013 samen met twee Italiaanse en Spaanse vissers en onderzoekers en Marloes Kraan van IARES een werkbezoek aan de Canadese oostkust. Het betrof een uitwisseling in het kader van de zogeheten Europese GAP2-project over onderzoekssamenwerking. Met als doel: ervaringen delen over praktijkonderzoek in de visserij. De Europese delegatie was te gast bij de Canadian Fisheries Research Network (CFRN).
Equity, Power Games, and Legitimacy: Dilemmas of Participatory Natural Resource Management
Barnaud, C. ; Paassen, A. van - \ 2013
Ecology and Society 18 (2013)2. - ISSN 1708-3087
social-ecological systems - natural-resource management - resilience - legitimacy - metasynthesis - perspective - framework - canada - agenda - shifts
Many papers in the recent literature on participatory approaches emphasize the need to take better account of the complexity of the social contexts in which they are conducted. Without attention to power asymmetries, there is a risk that the most powerful stakeholders will have greater influence on the outcomes of the participatory process than marginalized stakeholders. However, very few authors address the question of how to deal with such power asymmetries. This question puts designers of participatory processes in a dilemma. On the one hand, if they claim a neutral posture, they are accused of being naively manipulated by the most powerful stakeholders and of increasing initial power asymmetries; but, on the other hand, if they adopt a nonneutral posture and decide to empower some particular stakeholders, their legitimacy to do so is questioned. We test a particular posture to overcome this dilemma: that is, a “critical companion” posture, which strategically deals with power asymmetries to avoid increasing initial power asymmetries, and which suggests that designers should make explicit their assumptions and objectives regarding the social context so that local stakeholders can choose to accept them as legitimate or to reject them. Legitimacy is seen as the product of a coconstruction process between the designers and the participants. This posture was tested in the context of a participatory process conducted in northern Thailand to address a conflict between the creation of a national park and two local communities. While we show that this posture makes it possible for designers to be both strategic and legitimate at the same time, it also raises new questions and new dilemmas. Can we, and should we, really make all our assumptions explicit? How can we deal with stakeholders who refuse to engage in any form of dialog? We conclude that there is no “right” posture to adopt, but that designers need to be more reflexive about their own postures.
Characterisation of Phytophthora infestans Isolates Collected from Potato and Tomato Crops in Tunisia During 2006–2008
Harbaoui, K. ; Lee, T.A.J. van der; Vleeshouwers, V.G.A.A. ; Khammassy, N. ; Harrabi, M. ; Hamada, W. - \ 2013
Potato Research 56 (2013)1. - ISSN 0014-3065 - p. 11 - 29.
genotypic diversity - united-states - mating-type - northwestern washington - genetic-structure - populations - resistance - metalaxyl - migration - canada
Severe late blight epidemics in Tunisia in recent years prompted population studies on the pathogen responsible for this disease, Phythophthora infestans. Characterisation of 165 Tunisian P. infestans isolates collected from 2006 to 2008 was performed for the mating type and mt haplotype, while subsets were analysed for metalaxyl sensitivity (n¿=¿65), virulence on differential set of 11 R genes of Solanum demissum (n¿=¿31), aggressiveness on cv. Bintje (n¿=¿36) and measurement of the radial growth on agar medium at three temperatures (n¿=¿38). Most isolates from potato and all isolates from tomato had the A1 mating type. The A2 mating type was detected in the north-east and northern areas, but not in the north-west. All the A2 mating type isolates were metalaxyl resistant and seem to be part of a new generation of the P. infestans isolates which are more aggressive, with more complex races, and tolerant to higher temperatures. The increased severity of epidemics during 2006 to 2008 can be attributed to favourable weather conditions during growing seasons, adaptation of new genotypes, widespread phenylamide resistance in potato production regions and most probably incorrect spray programmes. In contrast to the presence of complex pathotypes in two major potato crop regions (north-east and northern areas), the P. infestans population detected in the other regions and in tomato crops was still relatively simple. Compared with the situation in Europe and the American continent, or even compared with neighbouring countries such as Algeria, the genetic changes in Tunisia are still comforting and require strict management decision on late blight control to avoid the spread of new P. infestans populations from Europe or neighbouring countries
Bioenergy from Mountain Pine Beetle Timber and Forest Residuals: A Cost Analysis
Niquidet, K. ; Stennes, B. ; Kooten, G.C. van - \ 2012
Canadian Journal of Agricultural Economics 60 (2012)2. - ISSN 0008-3976 - p. 195 - 210.
british-columbia - infested wood - canada
In light of the large volumes of pine killed in the interior forests of British Columbia (BC) by the mountain pine beetle, many forest sector participants are keen to employ forest biomass as an energy source. To assess the feasibility of a wood biomass-fired power plant in the BC interior, it is necessary to know both how much physical biomass might be available over the life of a plant and its location as transportation cost is likely to be a major operating cost for any facility. To address these issues, we construct a mathematical programming model of fiber flows in the Quesnel Timber Supply Area of BC over a 25-year time horizon. The focus of the model is on minimizing the cost of supplying feedstock through space and time. Results indicate that over the life of the project, feedstock costs will more than double, increasing from $54.60/bone-dry tonnes (BDt) ($0.039/kWh) to $116.14/BDt ($0.083/kWh).
Risicoanalyse import ei- en spermacellen van honingbijen uit de Verenigde Staten en Canada
Steen, J.J.M. van der; Cornelissen, B. - \ 2012
Wageningen : Plant Research International Wageningen UR, Business Unit Biointeracties en Plantgezondheid (Rapport / Plant Research International 486)
apis mellifera - sperma - honingbijen - bijenziekten - quarantaine - nederland - vs - canada - semen - honey bees - bee diseases - quarantine - netherlands - usa
Thresholds for Boreal Biome Transitions
Scheffer, M. ; Hirota, M. ; Holmgren, M. ; Nes, E.H. van; Chapin, F.S. - \ 2012
Proceedings of the National Academy of Sciences of the United States of America 109 (2012)52. - ISSN 0027-8424 - p. 21384 - 21389.
arctic forest-tundra - climate-change - fire regime - global resilience - interior alaska - tropical forest - white spruce - tree - savanna - canada
Although the boreal region is warming twice as fast as the global average, the way in which the vast boreal forests and tundras may respond is poorly understood. Using satellite data, we reveal marked alternative modes in the frequency distributions of boreal tree cover. At the northern end and at the dry continental southern extremes, treeless tundra and steppe, respectively, are the only possible states. However, over a broad intermediate temperature range, these treeless states coexist with boreal forest (~75% tree cover) and with two more open woodland states (~20% and ~45% tree cover). Intermediate tree covers (e.g., ~10%, ~30%, and ~60% tree cover) between these distinct states are relatively rare, suggesting that they may represent unstable states where the system dwells only transiently. Mechanisms for such instabilities remain to be unraveled, but our results have important implications for the anticipated response of these ecosystems to climatic change. The data reveal that boreal forest shows no gradual decline in tree cover toward its limits. Instead, our analysis suggests that it becomes less resilient in the sense that it may more easily shift into a sparse woodland or treeless state. Similarly, the relative scarcity of the intermediate ~10% tree cover suggests that tundra may shift relatively abruptly to a more abundant tree cover. If our inferences are correct, climate change may invoke massive nonlinear shifts in boreal biomes.
Subpermafrost groundwater systems: Dealing with virtual reality while having virtually no data
Ploeg, M.J. van der; Haldorsen, S. ; Leijnse, A. ; Heim, M. - \ 2012
Journal of Hydrology 475 (2012). - ISSN 0022-1694 - p. 42 - 52.
fresh-water ecosystems - axel-heiberg island - climate-change - north slope - permafrost - svalbard - mars - springs - canada - spitsbergen
Studies on the Earth’s hydrology in general thrive on abundant data, while data on certain groundwater systems are virtually absent as a result of their inaccessibility. This poses challenges for understanding and modeling such systems, yet modeling is often the only option to study them. When it comes to limited data availability, a simple model may have a better predictive performance than a complex model. In a case study of a subpermafrost groundwater system on Svalbard we applied three simplified models which do not cover all processes, and compared their outcomes. The results of all models were different and sometimes contrasting. By combining all model results within their associated assumptions we show how dynamic processes in data-limited subpermafrost groundwater systems can be interpreted. Using multiple interpretations of a system by making different assumptions can thus be used to understand processes in data limited groundwater systems. Our results also illuminate the fierce data scarcity of subpermafrost groundwater systems, and the necessity of resolving this.
Evaluating competing hypotheses for the origin and dynamics of river anastomosis
Kleinhans, M.G. ; Haas, T. de; Lavooi, E. ; Makaske, B. - \ 2012
Earth Surface Processes and Landforms 37 (2012)12. - ISSN 0197-9337 - p. 1337 - 1351.
rhine-meuse delta - upper columbia river - british-columbia - sediment transport - channel - netherlands - avulsion - canada - classification - bifurcation
Anastomosing rivers have multiple interconnected channels that enclose flood basins. Various theories potentially explain this pattern, including an increased discharge conveyance and sediment transport capacity of multiple channels, deltaic branching, avulsion forced by base-level rise, or a tendency to avulse due to upstream sediment overloading. The former two imply a stable anabranching channel pattern, whereas the latter two imply disequilibrium and evolution towards a single-channel pattern in the absence of avulsion. Our objective is to test these hypotheses on morphodynamic scenario modelling and data of a well-documented case study: the upper Columbia River. Proportions of channel and floodplain sediments along the river valley were derived from surface mapping. Initial and boundary conditions for the modelling were derived from field data. A 1D network model was built based on gradually varied flow equations, sediment transport prediction, mass conservation, transverse slope and spiral meander flow effects at the bifurcations. The number of channels and crevasse splays decreases in a downstream direction. Also, measured sediment transport is higher at the upstream boundary than downstream. These observations concur with bed sediment overloading from upstream, which can have caused channel aggradation above the surrounding floodplain and subsequent avulsion. The modelling also indicates that avulsion was likely caused by upstream overloading. In the model, multi-channel systems inevitably evolve towards single-channel systems within centuries. The reasons are that symmetric channel bifurcations are inherently unstable, while confluenced channels have relatively less friction than two parallel channels, so that more discharge is conveyed through the path with more confluences and less friction. Furthermore, the present longitudinal profile curvature of the valley could only be reproduced in the model by temporary overfeeding.
The economics of regulation in agriculture : compliance with public and private standards
Brouwer, F.M. ; Fox, G. ; Jongeneel, R.A. - \ 2012
Wallingford [etc.] : CABI - ISBN 9781845935573 - 278
landbouwbeleid - agrarische economie - regelingen - landbouw - milieubeleid - gezondheid - dierenwelzijn - europese unie - vs - canada - nieuw-zeeland - agricultural policy - agricultural economics - regulations - agriculture - environmental policy - health - animal welfare - european union - usa - canada - new zealand
This volume investigates the cost implications and competitiveness effects resulting from regulations and standards in the fields of environment, human health and animal welfare and production-linked rules of "good agricultural conditions" for a range of agricultural products in the EU, USA, Canada and New Zealand. Part I of the book (chapters 2-6) highlights changes taking place in developed country agricultures. Part II (chapters 7-11) offers a commodity approach linking public concerns with trade and competitiveness. Emerging policy perspectives are identified in Part III (chapters 12-16).
Vessel formation in relation to leaf phenology in pedunculate oak and European ash
Sass-Klaassen, U. ; Sabajo, C.R. ; Ouden, J. den - \ 2011
Dendrochronologia 29 (2011)3. - ISSN 1125-7865 - p. 171 - 175.
fagus-sylvatica l. - tree-rings - earlywood vessels - quercus-robur - red oak - canada - xylem - netherlands - dynamics - drought
The earlywood–vessel area of ring-porous species is related to environmental factors that prevailed during the time of vessel formation. However, limited knowledge is available on the time window during which environmental factors such as temperature, precipitation or flooding can be recorded in vessel area. The susceptibility of vessel area to capture these environmental signals is likely to be related to the timing and duration of vessel formation. Ring-porous species are known to have their new earlywood vessels formed before buds break to guarantee efficient water transport through the large earlywood vessels in the outermost tree ring. However, as leaf phenology differs in ring-porous species, also the timing of vessel formation may vary between species. In this study we investigated the timing and duration of earlywood–vessel formation in relation to phenological status in pedunculate oak (Quercus robur L.) and European ash (Fraxinus excelsior L.) growing at the same site. Microcores were taken from the stem periphery of ten oaks and five ashes in weekly intervals from March to the beginning of June in 2008. Leaf phenology was recorded in the same period. Vessel size was measured from the microcores to relate dynamics in vessel formation to the leaf phenological phases. We found that vessel formation in ash started well before bud swelling and much earlier as compared to oak. Although oak preceded ash in leaf phenology, earlywood–vessel formation in oak started on average more than 13 days later, but vessels enlarged faster than in ash. The formation of all earlywood vessels was completed in both species before leaves were fully expanded. These results indicate that timing and dynamics in vessel formation, as well as the relation between leaf phenology and vessel formation, can considerably differ between ring-porous species
Global river temperatures and sensitivity to atmospheric warming and changes in river flow
Vliet, M.T.H. van; Ludwig, F. ; Zwolsman, J.J.G. ; Weedon, G.P. ; Kabat, P. - \ 2011
Water Resources Research 47 (2011)2. - ISSN 0043-1397 - 19 p.
water temperature - air-temperature - stream temperatures - climate-change - thermal regime - united-states - new-brunswick - variability - models - canada
This study investigates the impact of both air temperature and river discharge changes on daily water temperatures for river stations globally. A nonlinear water temperature regression model was adapted to include discharge as a variable in addition to air temperature, and a time lag was incorporated to apply the model on a daily basis. The performance of the model was tested for a selection of study basin stations and 157 river temperature stations globally using historical series of daily river temperature, air temperature, and river discharge for the 1980–1999 period. For the study basin stations and for 87% of the global river stations, the performance of the model improved by including discharge as an input variable. Greatest improvements were found during heat wave and drought (low flow) conditions, when water temperatures are most sensitive to atmospheric influences and can reach critically high values. A sensitivity analysis showed increases in annual mean river temperatures of +1.3 °C, +2.6 °C, and +3.8 °C under air temperature increases of +2 °C, +4 °C, and +6 °C, respectively. Discharge decreases of 20% and 40% exacerbated water temperature increases by +0.3 °C and +0.8 °C on average. For several stations, maximum water temperatures on a daily basis were higher under an air temperature increase of +4 °C combined with a 40% discharge decrease compared to an air temperature increase of +6 °C (without discharge changes). Impacts of river discharge on water temperatures should therefore be incorporated to provide more accurate estimations of river temperatures during historical and future projected dry and warm periods
Collection of information on biorefinery research funding and research organisations (projects). Task 2.3.2 Outside Europe
Annevelink, E. ; Oever, M.J.A. van den - \ 2010
Wageningen : Wageningen UR - Food & Biobased Research (Star-Colibri Deliverable 2.3.2) - 124
vs - onderzoeksprojecten - onderzoeksinstituten - canada - china - india - japan - brazilië - biobased economy - bioraffinage - usa - research projects - research institutes - brazil - biorefinery
This report provides an outlook on research into biorefineries in the US, Canada, Australia, China, India, Japan and Brazil. The results will be used for benchmarking or to indicate new opportunities. The most recent EU-funded Specific Support Action projects (Bioref-Integ, Biorefinery Euroview, Biopol and Sustoil) on biorefinery knowledge were taken as a starting point for data collection for this report. Furthermore, input was taken from the (country) reports of the IEA Task 42 Biorefinery. Literature research was combined with a thorough scan of the web to find as much information as possible. This survey concentrated on finding basic information. No further analysis of the information has been made in this report.
Analysis of population development and effectiveness of mnagement in resident greylag geese Anser anser in the Netherlands
Klok, T.C. ; Turnhout, C. van; Willems, F. ; Voslamber, B. - \ 2010
Animal Biology 60 (2010)4. - ISSN 1570-7555 - p. 373 - 393.
density-dependence - brent geese - demographic-models - branta-canadensis - south sweden - goose - conservation - growth - scotland - canada
The resident Greylag goose population in the Netherlands has strongly increased in number which led to conflict with agricultural interests, public concern on goose hunting and legal debate on the need to regulate geese. Such a debate can be facilitated by insight in population development and the effectiveness of management options. In this paper we analyse the historic population development and apply density independent and density dependent models to investigate possible future population development and the impact of management on this development. We explored the influence of density dependence by applying the amount of gosling rearing habitat as the first limiting factor. The models were parameterised with life-history data of two well studied populations during their exponential growth phase as a proxy for the total Dutch population for which life-history data are unavailable. The effectiveness of two management options aimed to reduce population growth: culling birds and egg reduction are assessed with these models. The developed models can be used as a management tool to evaluate the consequences of different measures in advance of their implementation. The results show significant positive growth rates which approximate the growth rate of the total Dutch population based on census data. With density dependence in the amount of gosling rearing habitat the population will grow for another one or two decades before it stabilizes. Of the two considered management options culling birds is more effective in reducing bird numbers than egg reduction. This conclusion holds both under density independent and density dependent conditions.
Implications of Expanding Bioenergy Production from Wood in British Columbia: An Application of a Regional Wood Fibre Allocation Model
Stennes, B. ; Niquidet, K. ; Kooten, G.C. van - \ 2010
Forest Science 56 (2010)4. - ISSN 0015-749X - p. 366 - 378.
spatial price equilibrium - infested wood - canada - energy
Energy has been produced from woody biomass in British Columbia for many decades, primarily within the pulp and paper sector, using residual streams from timber processing to create heat and electricity for on-site use. More recently, there has been some stand-alone electricity production and an increase in the capacity to produce wood pellets, both using “waste” from the sawmill sector. Hence, most of the low-cost feedstock sources associated with traditional timber processing are now fully employed. Although previous studies modeled bioenergy production in isolation, we used a fiber allocation and transportation model of the British Columbia forest sector with 24 regions to demonstrate that it is necessary to consider the interaction between use of woody feedstock for pellet production and electricity generation and its traditional uses (e.g., production of pulp, oriented-strandboard, and others). We find that, despite the availability of large areas of standing mountain pine beetle-killed timber, this wood does not enter the energy mix in a dedicated salvage timber harvest to energy system. Further expansion of biofeedstock for energy is met by a combination of woody debris collected at harvesting sites and/or bidding away of fiber from existing users.