Minimum Area Requirements Research Articles

IMPLEMENTING MINIMUM AREA HARVESTING BLOCKS IN AN OPTIMIZED FOREST PLANNING MODEL1

ABSTRACT The spatial relationships between forest stands scheduled for harvesting are crucial for forest planning, once they affect directly environmental impacts and logistic aspects related to this operation. In this context, the objective of this study was to perform the optimized forest planning of a Pinus taeda, Pinus elliottii and Eucalyptus dunnii forest, composed by 236 stands, including minimum area constraints. Two approaches were applied for clustering harvesting activities. The first approach considered the inclusion of a set of constraints so-called ring inequalities, proposed by Carvajal et al. (2013). The second approach was based on the formulation proposed by Rebain and McDill (2003) for the creation of old-growth forest areas. Both formulations were capable to generate harvesting blocks with minimum area requirements, causing a reduction up to 5.1% in the objective function for the most restrictive scenario. We conclude that the formulation based on Carvajal et al. (2013) is the best alternative when only minimum area constraints are considered, due to the inferior number of constraints and superior performance in terms of the NPV generated.

A management strategy for the long-term conservation of the Endangered sand-dune lizard Liolaemus multimaculatus in the Pampean coastal dunes of Argentina

AbstractThe sand-dune lizard Liolaemus multimaculatus is an Endangered species endemic to the Pampean coastal dunes of Argentina. To inform the development of a future Action Plan for this species, we investigated the demography and conservation status of all remaining populations, and we suggest management actions appropriate to local needs. We used population viability analysis to assess extinction risk in three inbreeding scenarios and estimate the minimum viable population and the minimum area requirement. To assess the current status of each local population, we used information related to population size, human pressure and connectivity. The results were then used to set and prioritize conservation management actions at local level. Our models indicated that populations of > 2,400 individuals would be viable in the long term and that inbreeding depression has a strong effect on extinction risk. The southern patches of coastal dune contain the largest populations of sand-dune lizards, and they are also better connected and less threatened. We suggest land protection as the priority management action for populations larger than the minimum viable population, whereas habitat recovery, when possible, should be the priority for patches of coastal dune smaller than the minimum area requirement. Supplementation with a small number of individuals could stabilize unviable populations but should be considered only in certain situations.The long-term conservation of the sand-dune lizard will be feasible only if a conservation action plan is developed and implemented.

Nestedness of butterfly assemblages in the Zhoushan Archipelago, China: area effects, life-history traits and conservation implications

The nested subset pattern (nestedness) of faunal assemblages has been a research focus in the fields of island biogeography and conservation biology in recent decades. However, relatively few studies have described nestedness in butterfly assemblages in oceanic archipelago systems. Moreover, previous studies often quantified nestedness using inappropriate nestedness metrics and random fill algorithms with high Type I errors. The aims of this study are to examine the existence of nestedness and underlying causal mechanisms of butterfly assemblages in the Zhoushan Archipelago, China. We used the line-transect method to determine butterfly occupancy and abundance on 42 study islands from July to August 2014. We obtained butterfly life-history traits (wingspan, body weight and minimum area requirement) by field work and island geographical features (area and isolation) from the literature. We used the recently developed metric WNODF to estimate nestedness. Partial Spearman rank correlation was used to evaluate the associations of nestedness and island geographical features as well as butterfly life-history traits related to species extinction risk and colonization ability. The butterfly assemblages were significantly nested. Island area and minimum area requirement of butterflies were significantly correlated with nestedness after controlling for other independent variables. In contrast, the nestedness of butterflies did not appear to result from passive sampling or selective colonization. However, multi-year studies are needed to confirm that target effects are not muddling these results. Our results indicate that selective extinction may be the main driver of nestedness of butterfly assemblages in our study system. From a conservation viewpoint, we should protect both large islands and species with large area requirement to maximize the number of species preserved.

The minimum area requirements (MAR) for giant panda: an empirical study.

Habitat fragmentation can reduce population viability, especially for area-sensitive species. The Minimum Area Requirements (MAR) of a population is the area required for the population’s long-term persistence. In this study, the response of occupancy probability of giant pandas against habitat patch size was studied in five of the six mountain ranges inhabited by giant panda, which cover over 78% of the global distribution of giant panda habitat. The probability of giant panda occurrence was positively associated with habitat patch area, and the observed increase in occupancy probability with patch size was higher than that due to passive sampling alone. These results suggest that the giant panda is an area-sensitive species. The MAR for giant panda was estimated to be 114.7 km2 based on analysis of its occupancy probability. Giant panda habitats appear more fragmented in the three southern mountain ranges, while they are large and more continuous in the other two. Establishing corridors among habitat patches can mitigate habitat fragmentation, but expanding habitat patch sizes is necessary in mountain ranges where fragmentation is most intensive.

A review of applications of the six-step method of systematic conservation planning

Systematic Conservation Planning (SCP) is an approach to protected areas planning that follows a step-by-step process. Recent reviews have examined the use of key “biogeographic-concepts”, but an assessment of their use or effectiveness has not been done. We conducted a review of the literature on SCP to assess how the 6-step approach considers these concepts. Most of the 127 papers we reviewed varied in their application of SCP steps. Our findings suggest that protected areas plans are not effectively achieving conservation goals. Only six papers considered data uncertainty. Twenty papers used so-called “data free” conservation targets without clear rationales, and which have been shown to under-represent natural features. The median size of planning units applied (2500 ha) is too small to meet minimum area requirements for many species. We show how an examination of the variation in the ways that SCP is applied helps to identify best practices for achieving conservation effectiveness and efficiency. However, very few SCP efforts have been implemented, making it difficult to assess their effectiveness or efficiency in practice. Detailed examination of how SCP is implemented (perhaps focused on a specific region) can lead to a better understanding of how best to achieve large-scale conservation goals.

Planning for Desirable Land Uses in Periurban Landscapes: Application of a Spatial Concept for Territorial Sustainability

With the aim to test the categorical formulation of a spatial concept on the functional, desirable characteristics of land-use distributions inside periurban land- scapes, in the research we envisaged and developed an original quantitative method, deployed in nine study-cases worldwide. Increasingly facing a generic set of pressures from suburbanization and unregulated land-use change, unwanted spatial outcomes in those landscapes often arise after trespassing critical thresholds of ecosystems' processes inadvertently: Overriding the minimum-area requirements, for example, of crucial ecosystems providing basic ecological services to whole urban regions. Spatial concepts can be powerful tools for strategic planning of territorial systems, helping to avoid shortsighted plans and policies. From the narrative of a spatial con- cept supportive of strategic planning and regulatory policies for territorial sustain- ability (the Aggregates-with-Outliers -AWO), we developed an original synthetic, quantitative method fostering statistical analysis between diverse locales, years, and scales -as well desirable scenarios. From the joint maximization of size variance and land-use diversity (JMV+D mod- el), we evidenced deficits and potentials on the composition of heterogeneous peri- urban landscapes, from the universal perspective of the concept. It is considered a tool (among the many required) for the strategic planning of territorial sustainability in those landscapes, especially required of a flexible definition on the desirable spa- tial outcomes of plans and policies.

Concrete Depth on Moment Capacity of Reinforced Concrete Slab: Safety Performance

Aimed to determine whether structural safety response of reinforced concrete slab will fall short of the code target safety value for flexural system and also determine its relation to moment capacity and minimum flexural reinforcement area requirement in consideration of the influence of un-certainties associated with the design parameters. The randomness of the design parameters makes the present deterministic design overly conservative, as such; it is becoming increasingly difficult to ignore the importance of using reliability approach in structural design application, because of its known advantage in accounting for the inherent variability in both loads and resistance variables. The study examined moment capacity violation and parametric sensitivity analysis with different concrete strengths class and span lengths, subjecting the deterministically designed required slab depth to further decrease and obtained the safety index value using First Order Reliability Method. The results indicate that concrete strength has little influence on minima reinforcement requirement with a value of about 3% surge for 500 mm change in span, which also results in increased ultimate moment of resistance of the concrete section with marginal decline in safety value. Interestingly, the safety value from the reliability analysis with optimized slab depth is well above the target safety limit specified for RC slab.

Minimum area requirements for an at-risk butterfly based on movement and demography.

Determining the minimum area required to sustain populations has a long history in theoretical and conservation biology. Correlative approaches are often used to estimate minimum area requirements (MARs) based on relationships between area and the population size required for persistence or between species' traits and distribution patterns across landscapes. Mechanistic approaches to estimating MAR facilitate prediction across space and time but are few. We used a mechanistic MAR model to determine the critical minimum patch size (CMP) for the Baltimore checkerspot butterfly (Euphydryas phaeton), a locally abundant species in decline along its southern range, and sister to several federally listed species. Our CMP is based on principles of diffusion, where individuals in smaller patches encounter edges and leave with higher probability than those in larger patches, potentially before reproducing. We estimated a CMP for the Baltimore checkerspot of 0.7-1.5 ha, in accordance with trait-based MAR estimates. The diffusion rate on which we based this CMP was broadly similar when estimated at the landscape scale (comparing flight path vs. capture-mark-recapture data), and the estimated population growth rate was consistent with observed site trends. Our mechanistic approach to estimating MAR is appropriate for species whose movement follows a correlated random walk and may be useful where landscape-scale distributions are difficult to assess, but demographic and movement data are obtainable from a single site or the literature. Just as simple estimates of lambda are often used to assess population viability, the principles of diffusion and CMP could provide a starting place for estimating MAR for conservation.

Using ecological theory to develop recovery criteria for an endangered butterfly

Using ecological theory to develop recovery criteria for an endangered butterfly

Screening of pervaporation membranes with the aid of conceptual models: An application to bioethanol production

In this paper, we assess the performance of a given hydrophobic membrane from the conceptual design of a hybrid process formed by the hydrophobic membrane itself and the separation train located downstream. To this end, a single pervaporation experiment with a model ethanol–water mixture is needed to estimate the minimum area requirement of the hydrophobic membrane. Short-cut methods, on the other hand, can be used to estimate the minimum number of stages and reflux ratio of the distillation column. Estimation of the minimum area requirement for a hydrophilic membrane, which is considered to overcome the azeotropic composition, requires the integration of a spatially one-dimensional isothermal mass transfer model of the unit until the desired biofuel purity is achieved in the corresponding retentate stream.The idea behind the approach is that the performance of a given membrane must be measured taking into account the overall hybrid process given that the hydrophobic membrane itself performs only a part of the desired separation.The hybrid process is then assessed on the basis of a cost estimate using the minimum membrane areas of the two membrane units together with minimum number of stages and minimum reflux ratio of the distillation column among other structural and operating variables.The outcome allows for the screening of pervaporation membranes, and yields valuable insights into the nature of the process as well as the constraints that a hybrid process may face. Membranes can be assessed based on their overall process performance by this method; only the subset of membranes presenting the best economic figures can be considered for a further analysis.

Optimizing any-aged management of mixed boreal forest under residual basal area constraints

The current trend of forest management in many countries is reduced use of clear-felling and planting, and increased use of continuous cover management. In Finland, the new forest act of 2014 made all types of cuttings equally allowable on the condition that if the post-cutting residual stand basal area is too low, the stand must be regenerated within certain time frame. Forest landowner can freely choose between even- and uneven-aged management. This study developed a method for optimizing the timing and type of cuttings without the need to categorize the management system as either even-aged or uneven-aged. A management system that does not set any requirements on the sequence of post-cutting diameter distributions is called any-aged management. Planting or sowing was used when stand basal area fell below the required minimum basal area and the amount of advance regeneration was less than required in the regulations. When the cuttings of 200 stands managed earlier with even-aged silviculture were optimized with the developed system, final felling followed by artificial regeneration was selected for almost 50% of stands. Reduction of the minimum basal area limit greatly decreased the use of artificial regeneration but improved profitability, suggesting that the truly optimal management would be to use natural regeneration in financially mature stands. The optimal type of thinning was high thinning in 97–99 % of cases. It was calculated that the minimum basal area requirement reduced the mean net present value of the stands by 12–16 % when discount rate was 3–5 %.

White‐handed Gibbon (Hylobates lar) Core Area Use Over a Short‐Time Scale

AbstractCore areas represent small regions within animal home‐ranges intensively used during a given period of time. We assessed the quality of core areas relative to the rest of the home‐ranges (i.e., non‐core areas) of 11 groups of the territorial and highly frugivorous white‐handed gibbon (Hylobates lar) over a short‐time scale to reflect temporarily available resources. Weekly core areas included consistently higher densities of the gibbons' important foods compared to non‐core areas. Gibbon core areas partially overlapped at 46 percent with a model comprising the best hypothetical core areas based on a concentration map of available food sources. In addition, a maximization ratio estimated by dividing the cumulative dbh covered by gibbon core areas and the model reached an intermediate value. Gibbon core areas only partially mirrored food distribution probably because they represent a trade‐off between covering regions with important food locations and areas needed for other biologically relevant activities such as territory defense. Results do not support the concept that core areas can represent the minimum area requirement that would allow a gibbon group to survive and reproduce successfully irrespective of the time period considered, which indicates that core areas alone should not be treated as a conservation target.

ALOKASI SUMBERDAYA KAWASAN HUTAN RAKYAT KABUPATEN SUKABUMI, JAWA BARAT: PENDEKATAN MULTI-OBJECTIVE PROGRAMMING

<em>The economic and ecological objectives in the development of private forest are conflicting, thus led to deforestation. The objectives of the study were to analyze factors affecting farmers’s decision in determining for the aim (economic or ecological objectives) of their land management by using logistic regession, and to analyze resources allocation in private forest that gives the best compromise solution between economic and ecological objectives by multi-objective programming approach and scenarios. The result shows that farmers are still economic oriented in determining the aim of their land management, mostly affected by number of farm household, off-farm income, participation in farmer group meeting, participation in extention meeting and farmer’s experiance in farm factors. Land management scenario that the closest to the target value (Rp 39.907 billion per year) is land management with minimum land area requirement, so that the value received by farmers is Rp 21.038 billion per year. Capital is a limitting factor in optimizing the use of available resources.</em>

Predicting minimum area requirements of butterflies using life-history traits

The minimum area requirement (MAR) of a species is the amount of functional habitat necessary for population persistence. The accurate measurement of MAR in the field usually requires long and precise investigations of all resources used by the target organism. Here we tested if MAR could be predicted by body size and species-specific life-history traits. Using values of MAR collected on European butterflies, we related MAR to 17 life-history traits plus wing size (a correlate of body size). We show that four life-history traits and wing size were significantly related with MAR in European butterflies. Compared to a model with wing size only, the inclusion of these four traits (myrmecophily, thermal tolerance, mate searching strategy, and ovigeny) more than doubled the power of the predictions of MAR. Our study provides a first step towards a predictive theory of species spatial requirements, with strong applications in conservation biology.

Dehydration of natural gas using membranes. Part II: Sweep/countercurrent design and field test

Membrane technology is an attractive alternative to conventional glycol dehydrators for natural gas dehydration. While membranes with high water/methane selectivity are available, the separation performance of membrane systems is restricted by the moderate feed-to-permeate pressure ratio encountered in this application, resulting in high membrane area requirement and high methane loss. This paper (Part II of a two-part study) addresses that challenge by evaluating suitable process designs to overcome the limitations of feed-to-permeate pressure ratio, using a process simulation package. A design with a dry gas on the permeate side as a countercurrent sweep shows the best combination of low methane loss and minimum membrane area requirement. The design was experimentally evaluated by field testing a spiral-wound module that incorporates countercurrent operation, at a natural gas processing plant. The use of a dry sweep gas on the permeate side significantly increased water vapor flux across the membrane. For example, as sweep/feed flow rate ratio increased from 0% to 5.9% at a permeate pressure of 4.8bar, water flux increased by 2.5 times, from 0.13slpm/m2 (standard liter per minute per m2 membrane area) to 0.47slpm/m2. The measured water flux reached about 80% of the value calculated with the process simulation package for a perfect sweep/countercurrent module, confirming the suitability of the spiral-wound modules with countercurrent configuration for natural gas dehydration.

Influence of Patch Size and Shape on Occupancy by Shrubland Birds

Abstract. Populations of many shrubland bird species are declining in the eastern United States. Efforts to restore shrubland and early-successional forest may help to ameliorate these declines. However, uncertainty remains about how the size and shape of habitat patches and the surrounding habitat matrix affect patch occupancy by shrubland passerines. Our objectives were to determine if shrubland birds avoid small or irregularly shaped habitat patches and to identify minimum area requirements for area-sensitive species. Additionally, we sought to determine if the proportion of mature forest cover in the landscape influences patch occupancy. We surveyed 35 individual habitat patches in 2007 and 43 in 2008 for the presence of eight shrubland birds. Then, we modeled the probability of five of these species occupying an individual patch relative to patch area, patch shape, and percent forest cover within 1 km of the patch. We documented evidence of area sensitivity for the Yellow-breasted Chat (Icteria viren...

Minimum prey and area requirements of the Vulnerable cheetahAcinonyx jubatus: implications for reintroduction and management of the species in South Africa

AbstractIn South Africa there are efforts to manage reintroduced subpopulations of the Vulnerable cheetahAcinonyx jubatusin small reserves (10–1,000 km2) as a managed metapopulation. We estimated areas required to support cheetahs given varying prey densities, prey profiles and presence/absence of competing predators. A recent population and habitat viability assessment indicated that 20 subpopulations of 10 cheetahs or 10 subpopulations of 15 cheetahs are required to retain 90% of the heterozygosity of free-ranging cheetahs and to overcome stochastic events in the absence or presence of lionsPanthera leo, respectively. We estimate that 203 ± SE 42 km2(range 48–466 km2) is required to support 10 cheetahs in the absence of lions, whereas 703 ± SE 311 km2(166–2,806 km2) is required to support 15 cheetahs given equal numbers of lions, and 2,424 ± SE 890 km2(727–3,739 km2) given equal numbers of leopardsPanthera pardus, spotted hyaenasCrocuta crocuta, wild dogsLycaon pictusand lions. Existing subpopulations of cheetahs generally occur at densities higher than our mean predicted densities but usually within the range of predicted densities. The large area requirements of cheetahs have implications for the development of the managed metapopulation. Sourcing reintroduction sites of the sizes required to support recommended subpopulation sizes will be difficult. Consequently, innovative measures to increase the carrying capacity of reserves for cheetahs and/or to enlarge reserves will be required. Managers may be forced to stock cheetahs close to or beyond the carrying capacity of their reserves. Consequently, careful management of reintroduced subpopulations will be required to prevent declines in prey populations.

A block-based selection method for road network generalization

When road symbols are shown in a size proportionate to the reduced scale, several problems of legibility may arise concerning the urban blocks. By the method proposed in this paper, in order to overcome these problems, urban block areas are enlarged through amalgamation and the intervening roads in the amalgams are eliminated. This method includes two new approaches for computation of threshold used in determination of important roads based on the connectivity measure, and for definition of minimum block space and area requirements based on graphic limits. A block life cycle was designed for amalgamation of blocks. For the amalgamation process, a new algorithm was developed. The experimental testing indicates that important roads and the roads surrounding the urban area have been preserved. A simpler and more legible road network has been acquired. This method can be described as a more holistic approach as the buildings are taken into account. The problems arising in the experimental testing indicate that the cartographic selection/elimination process is not sufficient by itself for road network generalization, which can be assumed as one of the integral parts of Digital Earth. As well as the selection/elimination, processes such as displacement and caricaturizing are also needed.

Forest management strategies for dealing with fire-related uncertainty when managing two forest seral stages

Ecological values are an important aspect of sustainable forest management, but little attention has been paid to maintaining these values when using traditional linear programming (LP) forest management planning models in uncertain planning environments. We embedded an LP planning model that specifies when and how much to harvest in a simulation model of a “managed” flammable forest landscape. The simulation model was used to evaluate two strategies for dealing with fire-related uncertainty when managing mature and old forest areas. The two seral stage areas were constrained in the LP planning model to a minimum of 10% of the total forest area and the strategies were evaluated under four representative fire regimes. We also developed a risk analysis tool that can be used by forest managers that wish to incorporate fire-related uncertainty in their decision-making. We found that use of the LP model would reduce the areas of the mature and old forest to their lower bound and fire would further reduce the seral areas below those levels, particularly when the mean annual burn fraction exceeds 0.45% per annum. Increasing the minimum area required (i.e., the right-hand side of the constraint) would increase the likelihood of satisfying the minimum area requirements.

Quantifying movement patterns for shark conservation at remote coral atolls in the Indian Ocean

Grey reef sharks (Carcharhinus amblyrhynchos) are apex predators found on many Indo-Pacific coral reefs, but little is known about their movement patterns and habitat requirements. We used acoustic telemetry to determine movements and habitat use of these sharks at the isolated Rowley Shoals atolls, 250 km off the coast of north-western Australia. We equipped 12 male and 14 female sharks ranging from 0.79 to 1.69 m in total length with transmitters that were detected by an array of 11 strategically placed receivers on two atoll reefs. Over 26,000 detections were recorded over the 325 days of receiver deployment. No sharks were observed to move between reefs. Receivers on the outer slopes of reefs provided nearly all (99%) of the detections. We found no differences in general attendance parameters due to size, sex or reef, except for maximum period of detection where larger sharks were detected over a longer period than smaller sharks. Male and female sharks were often detected at separate receivers at the outer slope habitat of one reef, suggesting sexual segregation, but this pattern did not occur at the second reef where males and females were detected at similar frequencies. We identified two patterns of daily behaviour: (1) sharks were present at the reef both day and night or (2) sharks spent more time in attendance during day than at night. Fast Fourier transforms identified 24-h cycles of attendance at the reef and a secondary peak of attendance at 12 h for most sharks, although no individuals shared the same attendance patterns. Our study provides baseline data that can be used to optimise the minimum area and habitat requirements for conservation of these apex predators.