Maximum Sustainable Production Research Articles

Estimation of life history parameters of the Gangetic leaffish, Nandus nandus from southern coastal waters of Bangladesh: Implications for sustainable management

The Nandus nandus (Hamilton, 1822) is a highly prized food fish that possesses significant nutritional and commercial worth. Bangladesh, India, Pakistan, Malaysia, Myanmar, Thailand and Viet Nam are the countries where it is endemic. The IUCN Bangladesh has classified this species as near endangered due to its current progressive decline. Hence, immediate actions are necessary to efficiently manage the fishery in this country. To address this issue, a comprehensive understanding of its life history parameters is required. This study aimed to examine the growth characteristics, recruitment length, sexual maturity, mortality, exploitation rate, and maximum sustainable production of N. nandus in Bangladesh's southern coastal waters. Samples were taken every month from January through December of 2021. Our study indicates that N. nandus grows in an isometric manner. The estimated asymptomatic length of this species is 18.0 cm in total length (TL), growing at a rate of 1.30 year−1. The growth performance index of this species was determined to be 2.62, and the projected lifespan was calculated to be 2.31 years. The initial length at recruitment was measured to be 9.5 cm TL, whie the size at first sexual maturity was recorded to be 9.4 cm TL. With the contributions of the natural mortality rate (2.26 year−1) and the fishing mortality rate (1.86 year−1) the total mortality rate was found to be 4.12 year−1. The exploitation rate, determined to be 0.45, surpasses the upper limit of sustainable yield criteria set at 0.37. Therefore, it is imperative to implement strategies to avoid excessive fishing and guarantee the long-term control of N. nandus populations.

Low optimal fisheries yield creates challenges for sustainability in a climate refugia

AbstractReducing resource depletion and promoting ecosystem‐based management are considered key climate change adaptation policies. Therefore, the resource status of an identified climate refugia in a semi‐enclosed bay on the Kenya–Tanzania border was evaluated for sustainability. Both fisheries stock and catch assessment methods found low production and excess effort. Stock recovery in closures (up to 45 years) determined the best‐fit r and K values, which established a maximum sustainable production (MSY) of 2.98 ± 0.45 (SEM) tons/km2/year. Stock estimates in the bays' fishing grounds indicated that biomass was below the MSY and predicted to produce 1.8 ± 1.0 (SEM) or 1.1 ton/km2/year below the optimal MSY. However, landed fish at five studied fishing villages varied greatly from 0.22 to 2.9 tons/km2/year. MSY in the refugia was therefore considerably lower than estimates in nearby ocean‐exposed locations, which has been estimated at 5–7 tons/km2/year. Therefore, low to modest capture rates of fish will be required to allow the recovery needed to achieve sustainability and restore the refugia's ecology. The refugia's highest stocks and near‐MSY yields were captured in the national reserve. Therefore, broader implementation of the reserve's gear‐restriction policies should restore fisheries. High spatial variability in yield patterns indicate interactions between fisheries management, compliance, trade connections, and governance. In climate refugia, reducing cumulative impacts will require knowing and managing for lower fisheries production limits.

An Ecopath perspective on the maximum sustainable yield of a macrophyte infested wetland in Eastern India

Wetlands are recognized as one of the most productive aquatic ecosystems. This high productivity supports its enormous biodiversity, aiding a scope for the small scale fisheries within it. Basically, these wetlands act as platforms for culture-based fisheries (CBF) i.e practice of stocking fish seeds and harvesting the grow out fishes at later. Often in tropical wetlands, the high nutrient load and high temperature enable the luxurious growth of macrophytes. Moreover, this macrophyte infestation is considered as a bottleneck for wetland managers. Facing a similar situation our studied Beledanga wetland is a macrophyte-infested wetland and the invasive Eichhornia crassipes is the most dominant macrophyte species. Owing to the macrophyte problem, Grass carp have been stocked in it as a biocontrol agent, as grass carp is a known biocontrol agent for the macrophyte infestation situation and simultaneously it will raise the fish production. To ensure maximum sustainable production from the wetland by harnessing with the available resources, it is necessary to acquire knowledge about the system’s ecological status and its ecological networks. Thus, the Ecopath based mass-balanced model is one of the best suitable tools to know about the ecological organization of this Beledanga wetland. Considering the available data (observational and literature data), this study has constructed a mass-balanced Ecopath model with 14 functional groups including all fish groups, birds, plankton, benthos and detritus. It has been found that the zooplankton and benthos are the most utilized group and the birds are the keystone group in this wetland system. This wetland possesses a lower transfer efficiency as well as a low Finn’s cycling index (0.224%). The system is found as an immature system with moderate ascendancy and system reserve (overhead). Moreover, concerning the ecologically sustainable production from this wetland more virtual mass-balanced models were developed (i) to evaluate the optimum grass carp stocking to manage the macrophyte population and (ii) to assess the impact of the Eichhornia on the system functioning. The results show that the system can harbour 1.5 times more grass carp biomass than the present without hampering sustainability. Concerning the impact of Eichhornia, it has been noticed that this macrophyte affects the maturity and transfer process of the system. Moreover, its huge biomass only accumulates more detritus in the ecosystem.

Dynamics, stability and sustainable optimal control in wolf-moose systems

A wolf-moose predator-prey system is defined as a nonlinear continuous time differential equation system. The parameters are estimated via a discretized approximation and empirical data from Isle Royale, USA, representing a 61 year period. All parameter estimates confirm the hypotheses and all P-values are below 5%. Possible dynamic equilibria are determined as explicit general functions of the parameters and as numerical values based on the empirical data. General dynamic properties of the system are determined via phase -plane analysis and nonlinear simulation. The nonlinear system is also linearized close to the single equilibrium with two strictly positive populations. The explicit equations of the time path of the linearized system are compared to the nonlinear simulation. Both methods give almost identical solutions close to the equilibrium. Far from the equilibrium, the time paths of the two methods deviate considerably. The solution is a stable converging spiral (center) (unstable diverging spiral) in case the system equilibrium prey population is located at a higher (the same) (lower) level than the population level that gives maximum sustainable net production. Based on the empirically determined expected parameter values, the system is stable but converges very slowly, as a spiral, to the two-species equilibrium. The estimated standard deviations of the parameters can be used to determine the probability that the system solution is a center or an unstable diverging spiral. The optimal management of the wolf-moose system is also determined via sustainable optimal control. Moose hunting and adjustments of the wolf population based on different prices and values of sustainable population levels are derived. Optimal hunting and stock levels are determined and reported as explicit functions of all parameters and prices.

Exploitation level of shortfin scads fish (Decapterus macrosoma) caught with purse seine in Bulukumba waters, South Sulawesi

Shortfin scads fish is a pelagic fish that has an important role in the economic sector of fishermen in South Sulawesi waters. In the last five years, there has been a decline in catch resulting from uncontrolled exploitation. However, there is no control instrument for the exploitation of shortfin scads fish to date, hence, there is a concern that the sustainability of shortfin scads fish resources will be threatened. This study aimed to determine the exploitation level of shortfin scads fish (Decapterus macrosoma) caught with a purse seine. The research was carried out in the waters of Bulukumba Regency, South Sulawesi, from April to August 2018. The method used was direct observation. Data on catches were recorded based on the fish species caught at the time of hauling. Data time series of shortfin scads fish and effort data tabulated from fisheries statistical data. Maximum sustainable yield (MSY) of shortfin scads fish in Bulukumba waters in 2016-2017 exceeded the maximum sustainable production (MSY) of 10,739 tons/year (overfishing). The regression analysis between effort and CPUE Schafer model, showed the estimation parameter intercept value (a) 42.38620491, slope (b) -0.041823411. The equality relationship interpreted as the fishing effort for f units per year will reduce the production value (CPUE) of shortfin scads fish by 42,386 tons/year. The estimation of sustainable potential value (MSY) of shortfin scads fish in Bulukumba waters was 10,739 tons/year, while the optimum fishing effort (fopt) was 507 units/year and the total allowable catch (TAC) 8,591 tons/year.

Critical Biofilm Growth throughout Unmodified Carbon Felts Allows Continuous Bioelectrochemical Chain Elongation from CO2 up to Caproate at High Current Density

Current challenges for microbial electrosynthesis include the production of higher value chemicals than acetate, at high rates, using cheap electrode materials. We demonstrate here the continuous, biofilm-driven production of acetate (C2), n butyrate (nC4), and n-caproate (nC6) from sole CO2 on unmodified carbon felt electrodes. No other organics were detected. This is the first quantified continuous demonstration of n-caproate production from CO2 using an electrode as sole electron donor. During continuous nutrients supply mode a thick biofilm was developed covering the whole thickness of the felt (1.2 cm deep), which coincided with high current densities and organics production rates. Current density reached up to -14 kA m-3electrode (-175 A m-2). Maximum sustained production rates of 9.8 ± 0.65 g L-1 day-1 C2, 3.2 ± 0.1 g L-1 day-1 nC4, and 0.95 ± 0.05 g L-1 day-1 nC6 were achieved (averaged between duplicates), at electron recoveries of 60-100%. Scanning electron micrographs revealed a morphologically highly diverse biofilm with long filamentous microorganism assemblies (~400 µm). n-Caproate is a valuable chemical for various industrial application, e.g. it can be used as feed additives or serve as precursor for liquid biofuels production.

Governance and assessment of small-scale data-limited Arctic Charr fisheries using productivity-susceptibility analysis coupled with life history invariant models

Governance of fisheries in Canada’s North is shared between communities, Inuit land claim management boards and the Canadian Department of Fisheries and Oceans under co-management systems outlined in the Nunavut Land Claim Agreement and the Inuvialuit Final Agreement. The management, conservation and optimization of Arctic Charr resources remain complicated by data paucity; by biological complexity of Arctic Charr stocks; climate change impacts; and by the lack of adapted stock assessment tools and co-management frameworks linking Inuit traditional knowledge with scientific expertise. The current state of Arctic Charr fisheries in Nunavut and the Northwest Territories is reviewed and alternatives presented for the evaluation of Arctic Charr stocks using intra-specific life history diversity as a basis for risk and quantitative assessments. The approach fits well with the shared governance model in that the biological characteristics at the root of the analysis, such as size at spawning and maximum length (life history metrics), can be observed through Inuit knowledge and/or through scientific sampling carried out by community members. Assessment is developed as a two stage process using productivity-susceptibility analysis and life history invariant models to determine the maximum sustainable production. The resulting analytical model can but updated through further ecological observations from the community and field sampling. The approach provides for active engagement by the fishers in the process of stock assessment. These science alternatives can be used by managers within the co-management framework to maximize sustainability of Arctic Charr fisheries.

THE ECONOMIC DIMENSION TO THE PRODUCTION OF FISH LAKE QARUN IN FAYOUM GOVERNORATE

lake Qarun is considered as the third largest lake in the Arab Republic of Egypt, and it is the main reservoir of agriculture drainage water in the province of Fayoum. The salinity increased in the lake Qarun from 32.45% in 2015 to about 34.3% in 2016, which caused declining production of fish, and the disappearance of some fish species with deterioration of the productivity of other species. The fish production by the lake decreased from 41.0% in 1995 to about 20.2% in 2014 of the total production of fish in Fayoum governorate. The study aims to identify the fish production at the lake applying the standard functions of production and costs, estimate the maximum sustainable yield (MSY), maximum rate of fishing efforts, and identify the most important marketing problems facing fishermen. Also, the study searching the marketing problems of fish at Qarun lake.The study results showed that white shrimp represents about 86.7% of total production at the lake, and its relative importance decreased compared with other fish species such as tilapia, mullet and Sole by about 9.54%, 1.91%, 1.82%, respectively .The average total costs were 243.98 Egyptian Pounds / Effort, and the average total revenue was586.36 Egyptian Pounds / Effort. The average net return was 342.37 Egyptian Pounds / Effort, which means that every Egyptian Pound invested in fishing at Lake Qarun had 0.403 Egyptian Pounds.The value of production elasticity, showed that increasing total input used at the Lake Qarun by 1% will increase production by 1.403%. To get the maximum sustainable yield at Lake Qarun, each effort need to produce 331.5 kg / Effort, and the average production of 262.8 kg / Effort.Compare actual and optimal production per effort, last result required to increase production by 68.7 kg / Effort. The production level which maximize profits was 508.0 kg / Effort. The maximum sustainable production (MSY) at the lake was 4303.4 tons per year, an increase of 39.6% from the average study of about 3082.3 tons, period, and that the actual fishing effort and estimated at 542 compound has exceeded the maximum fishing effort to the production estimated at 356 compound, an increase of approximately 52.3%.The most important marketing problem was the lack of market equipment’s by 85.2%, and the most important fishing problem was the disappearance of many species of fish species by 100%, and the most important sources of Lake Qarun water pollution were agricultural, industrial and sewage pollution by 98.4.%, 93.4 %, and 91.8%. respectively

木質資源動態予測モデルの構築ならびに資源活用可能性に関する評価

Around the betwixt mountainous areas in Japan, regional decline due to depopulation and aging has become serious. So, the regional redesign and economical promotion are required to maintain the quality of life and area. The fact that the economic value of wood resources has declined and employment has been lost in the 1970s is closely related to depopulation and aging in the betwixt mountainous areas. Therefore, in this research, we evaluate the CO2 emission reduction and the economic revitalization effect of low carbonization countermeasures by means of regional redesign and reestablishment of forestry for rural areas. In the previous paper, we designed a model household to estimate energy consumption and demand for building materials with the aim of evaluating various CO2 emission reduction effects by low carbonization countermeasures. Subsequently, in this paper, the amount of wood resources that can be used continuously for the future is evaluated by constructing “the dynamic prediction model for the regional wood resources” based on forest GIS data. By the prediction model, not only the amount of wood resources that can be sustainably utilized for the future, we can also evaluate forestry production activities to respond to the demand of wood resources. From these results, we can analyze the relationship between the demand for wood resources and the amount of resources available in the case of rebuilding from traditional farmhouses to urban houses and changing heating sources from kerosene to firewood. This study was targeted at Inami Town, Wakayama Prefecture. In Inami Town, the total population is about 8,700 and the number of households is about 3,300, and this town is the underpopulated area prescribed in the Act on Special Measures for Promotion for Independence for Underpopulated Areas. The resulting findings are as follows. 1) In the target area, significant aging of wood resources has been proceeding, so the rapid maintenance is desired not only from the absorption of CO2 but also from the aspect of maintaining the value of materials. 2) The current amount of transport wood from the mountain was estimated about 12% of the annual growth. Due to the further aging of resources, the amount of growth sharply will decrease in the near future. 3) As a sustainable and maximally utilizable condition of wood resources, the appropriate rate of the harvesting was evaluated for this area by the prediction model. 4) The average (for 100 years) amount of wood resources available for building materials was estimated 6,249 m3 and for energy was 16,553 m3, the total was equivalent to about 20 times the amount of transport wood from the mountain in the current status. 5) The dynamic prediction model made it possible to evaluate the transportation amount from the logging of wood resources to the sawmill plant, the area of new afforestation after cutting and the labor volume required for those work. 6) While the total transported material volume increases by about 50% after 100 years due to poplar conversion, labor volumes required for transportation in the forest only increased by 8% on average in 100 years, this indicate that efficient wood resources production will be possible by poplar conversion. 7) When the maximum sustainable production conditions are assumed, demand for building materials in the town will be satisfied in 6 years, it will become possible to use outside Inami Town. Even if all heating is assumed for firewood as a heat source, it is possible to use around 10,000 m3 per year outside Inami Town.

Study on Physicochemical Properties of Rice Varieties in Fiji

<p>Determination of the most suitable rice varieties is to ensure the maximum sustained production for continuous economical development. In Fiji, multiple varieties of rice exist and it becomes important to identify the varieties best suited for commercial production to improve overall food security and to reduce the dependency on imports. Twenty varieties of rice cultivated in Fiji were analysed at IRRI to determine which varieties had the best characteristics for potential production. Results were correlated to determine if one variable would have an impact on another. Results indicated significant negative correlation between amylose content and the weight of milled rice (-0.715).</p>

Data limited assessment of selected North American anadromous charr stocks

Charr populations are particularly susceptible to change, either from the application of harvest or environmental conditions such as climate variation. As an alternative to conventional fishery analysis, we analyze the sustainability and viability of selected North American charr stocks using a number of approaches. We compare several methods for data limited situations to determine the allowable harvest of the Ekalluk River, Paliryauk River, Halovik River, Jayco Lake and Lauchlan River Arctic Charr including Cadima’s Maximum Sustainable Production Method, Hierarchical Bayesian Surplus Production Models, a Status Quo Total Allowable Harvest method, Long-term Average Catch methods and the Depletion-Corrected Average Catch method. Each method provided a similar outcome in terms of the relative importance of stocks to the fishery. The predicted sustainable harvest of larger stocks such as the Ekalluk and Jayco varied more according to the method applied than the other stocks studied. While not a replacement for more comprehensive fishery models these methods can be useful in data poor situations.

Corrigendum to: Impacts of level of utilisation by grazing on an Astrebla (Mitchell grass) grassland in north-western Queensland between 1984 and 2010. 2. Plant species richness and abundance

The occurrence of interstitial species in Astrebla grasslands in Australia are influenced by grazing and seasonal rainfall but the interactions of these two influences are complex. This paper describes three studies aimed at determining and explaining the changes in plant species richness and abundance of the interstitial species in a long-term sheep utilisation experiment in an Astrebla grassland in northern Queensland. In the first study, increasing utilisation increased the frequency of Dactyloctenium radulans (Button grass) and Brachyachne convergens (Downs couch) and reduced that of Streptoglossa adscendens (Mint bush). In the second study, seasonal rainfall variation between 1984 and 2009 resulted in large annual differences in the size of the seed banks of many species, but increasing utilisation consistently reduced the seed bank of species such as Astrebla spp. and S. adscendens and increased that of species such as B. convergens, D. radulans, Amaranthus mitchellii (Boggabri) and Boerhavia sp. (Tar vine). In the third study, the highest species richness occurred at the lightest utilisation because of the presence of a range of palatable forbs, especially legumes. Species richness was reduced as utilisation increased. Species richness in the grazing exclosure was low and similar to that at the heaviest utilisation where there was a reduction in the presence of palatable forb species. The pattern of highest species richness at the lightest grazing treatment was maintained across three sampling times, even with different amounts of seasonal rainfall, but there was a large yearly variation in both the density and frequency of many species. It was concluded that the maintenance of highest species richness at the lightest utilisation was not aligned with other data from this grazing experiment which indicated that the maximum sustainable wool production occurred at moderate utilisation.

Impacts of level of utilisation by grazing on an Astrebla (Mitchell grass) grassland in north-western Queensland between 1984 and 2010. 2. Plant species richness and abundance

The occurrence of interstitial species in Astrebla grasslands in Australia are influenced by grazing and seasonal rainfall but the interactions of these two influences are complex. This paper describes three studies aimed at determining and explaining the changes in plant species richness and abundance of the interstitial species in a long-term sheep utilisation experiment in an Astrebla grassland in northern Queensland. In the first study, increasing utilisation increased the frequency of Dactyloctenium radulans (Button grass) and Brachyachne convergens (Downs couch) and reduced that of Streptoglossa adscendens (Mint bush). In the second study, seasonal rainfall variation between 1984 and 2009 resulted in large annual differences in the size of the seed banks of many species, but increasing utilisation consistently reduced the seed bank of species such as Astrebla spp. and S. adscendens and increased that of species such as B. convergens, D. radulans, Amaranthus mitchellii (Boggabri) and Boerhavia sp. (Tar vine). In the third study, the highest species richness occurred at the lightest utilisation because of the presence of a range of palatable forbs, especially legumes. Species richness was reduced as utilisation increased. Species richness in the grazing exclosure was low and similar to that at the heaviest utilisation where there was a reduction in the presence of palatable forb species. The pattern of highest species richness at the lightest grazing treatment was maintained across three sampling times, even with different amounts of seasonal rainfall, but there was a large yearly variation in both the density and frequency of many species. It was concluded that the maintenance of highest species richness at the lightest utilisation was not aligned with other data from this grazing experiment which indicated that the maximum sustainable wool production occurred at moderate utilisation.

The coexistence of Baird's tapir (Tapirus bairdii) and indigenous hunters in northeastern Honduras

The Baird's tapir (Tapirus bairdii) is a popular game species throughout Central America, particularly among indigenous populations, and is currently endangered. Research on Miskitu hunting was conducted over 4 months in a remote region in northeastern Honduras that overlaps with the Río Plátano Biosphere Reserve. The hunting zone was mapped together with hunters and interviews were conducted with elders and other community members about tapir hunting. Results show that tapir harvesting is targeted toward specific habitats at specific times of year. Harvest rates for one year suggest that tapir hunting in the area exceeds estimates of maximum sustainable production. Nevertheless, field surveys reveal the presence of tapir within 1 km of the community, and its harvest tends to be nearby, in both forested and agricultural landscapes, suggesting that the animal has not been depleted in the area. It appears that the existence of forest areas adjacent to the hunting zone that do not experience hunting, together with the anthropogenic habitats created through shifting cultivation, are factors that help explain the presence of tapirs in the area. The article concludes with a discussion regarding the potential positive role of indigenous hunters in tapir conservation throughout its distribution range.

A basic design for a multicriteria approach to efficient bioenergy production at regional level

In Germany, government policies supporting the growth of renewable energies lead to a rapid increase in energy crop cultivation. This increase is linked to possible conflicts between different sustainability goals which so far have been rarely considered in the planning procedure. This article looks at different approaches of assessment and planning methods on a region-specific level. It describes the methodology of the project Efficient Bio-Energy in the Perspective of Nature Conservation - Assessment and Recommendations to Protect Biodiversity and Climate which aims to establish the basis for an integrated sustainability assessment of energy crop cultivation for decentralized energy production in Germany and has been conducted by the author. The method takes into account the three main requirements of agricultural profitability, greenhouse gases (GHG) efficiency, and environmental sustainability of energy crop cultivation for decentralized energy production and has been applied for two sample regions. Using ArcGIS, the suitability of energy crops can be displayed, and regional aspects can be considered by overlaying and intersecting the individual output of all three requirements. This allows the definition of ‘no-go’ areas as well as the overall estimation of the maximum sustainable production capacity for each energy crop or energy path in a specific region. It enables an estimation of the profitability and GHG efficiency of energy crop cultivation paths at regional or communal level under consideration of different indicators for environmental sustainability. The article closes with a discussion of the methodological challenges of this integrative method. The conclusion gives an outlook in which planning and policy processes could be beneficial to apply such an integrative method in order to assess the suitability of certain landscape areas for energy production paths.

Common patterns, common drivers: comparative analysis of aggregate surplus production across ecosystems

Marine ecosystems are dynamic, often have open boundaries, and their overall pro- ductivity responds nonlinearly to multiple drivers acting at multiple temporal and spatial scales, under a triad of influences: climatic, anthropogenic, and ecological. In order to further our under- standing of how the structure and functioning of marine ecosystems influence and regulate pat- terns of fisheries production, and how they are affected by this triad of drivers, a comparative approach is required. We apply a system-level surplus production modeling approach to the total aggregated catch and biomass of all major targeted fish species in 12 exploited Northern Hemi- sphere ecosystems. We use 2 variations of a surplus production model: a regression model and a dynamic model, each fit with and without environmental and biological covariates. Our aims were to explore (1) the effects of common drivers at the basin scale and their relative influence within the triad of drivers among systems, (2) the impact of covariates on biological reference points and implications for fisheries management, and (3) the relationship between maximum sustainable yield (MSY) and production. Our results show that the environment affects estimates of system- level MSY across all ecosystems studied and that specifically water temperature is a major influ- ence on productivity. Emergent properties of northern hemisphere systems suggest that MSY val- ues and optimal exploitation rates are relatively consistent: MSY ranges between 1 and 5 t km �2 and optimal exploitation rate between 0.1 and 0.4 yr �1 . Finally, we suggest that the relationship between fisheries yield and primary production is not as simple as suggested in other studies. These results put fisheries in a broader ecosystem context and have implications for an ecosystem approach to management.

Sustainability of hunting, population densities, intrinsic rates of increase and conservation of Papua New Guinean mammals: A quantitative review

New Guinea’s mammalian fauna consists of a unique assemblage of relatively small sized (0.5–13.5 kg) marsupial mammals, the hunting of which provides a major source of protein for local communities. However, the impact of hunting and the influence of the marsupial life-history strategies on the sustainability of hunting are unknown. Anthropological studies of subsistence hunting and published life-history data for Australasian marsupial mammals were quantitatively reviewed to determine the major sources of game and annual harvest, and estimate intrinsic rates of population increase ( r max) and population densities. These data were used to estimate extraction versus maximum sustainable production (MSP) and make a preliminary estimate of the sustainability of hunting. There were significant negative relationships between increasing body size and decreasing r max and decreasing population densities, which were further influenced by phylogeny and diet, and appear very similar to relationships found for placental mammals in Afrotropical and Neotropical forests. The estimated biomass of mid-sized marsupial mammals (923 kg/km 2) in Papua New Guinea is also comparable with densities of placental mammals in other evergreen tropical forests. Intrinsic rates of increase ranged from 0.28 for tree-kangaroos (Macropodidae) and 0.29 for cuscus (Phalangeridae), up to 5.14 for bandicoots/echymipera (Peroryctidae). Estimated population densities ranged from 0.4–4.0 animals/km 2 for long-beaked echidna ( Zaglossus sp.) to 150–340 animals/km 2 for ringtails (Pseudocheridae). Extraction rates of game in three studies averaged 23.5 ± 9.9 kg/km 2/year, with cuscus and bandicoot species numerically comprising the main game, although cuscus are the most important source of protein. Rates of extraction in Papua New Guinea versus rates of production demonstrate that long-beaked echidna, tree-kangaroos and cuscus are likely to be hunted unsustainably. In contrast hunting of bandicoots and ringtails was lower than maximum production levels, and the high intrinsic rate of increase of bandicoots means that they can potentially provide a sustainable source of protein, in preference to scarcer and intrinsically slower breeding species.

Regionally optimized forest management under changing climate

The purpose of this study was to optimize forest management for a forest region (the total area of forest and scrub land 1.54 mill. ha) under changing climate by using the large-scale forestry scenario model MELA and sample plot data from the geo-referenced National Forest Inventory (NFI). The MELA model is based on integrated simulation and optimisation; in the simulation it utilises empirical tree-level models into which the impacts of climate change were introduced by transfer variables derived by using the physiological model FinnFor. Six scenarios with differences in climate and forest management were defined. In simulations, the accelerating tree growth caused by climate change resulted in an increase in maximum sustainable removal of trees at regional level. Changes in regionally optimized forest management were also detected during the analysis period of 30 years; the proportion of thinnings increased because the stands fulfilled the thinning requirements earlier than in the current climate. This study was the first attempt to solve endogenously maximum sustainable timber production and corresponding forest management at the regional level under different climate scenarios. When implemented in the MELA system, which is widely used in Finnish forestry, the transfer variables offer means of disseminating the results from physiological studies to planning of adjustment and mitigation measures under changing climate.

Guayule agronomics: establishment, irrigated production, and weed control

Vast amounts of information on the cultivation of guayule were generated by the Emergency Rubber Project (ERP) during World War II, but there were still knowledge gaps in many aspects of guayule growth and development. Multi-disciplinary, multi-institutional research studies from the late 1970s to the present have helped to fill these gaps. Transplanting has been and still is the most reliable method of guayule stand establishment. Direct-seeding has been successful in research plots in Texas, New Mexico, and Arizona, using seed conditioning techniques and precision planting. The consistent production of high quality guayule seed is essential for reliable establishment by direct-seeding. Although, guayule is a semiarid, drought-tolerant shrub, it must have irrigation for maximum sustained production. Guayule is not an efficient user of water, and may require from 1000 to 1300 mm of applied water (irrigation + rainfall) to attain maximum production. The quantity of irrigation water required depends primarily on the growing region and yield desired. Growers must determine a goal for economical biomass and rubber yield, and adjust inputs accordingly. Research has revealed that guayule responds to nitrogen more than any of the other major nutritional elements. The crop water stress index has been developed for guayule and is a valuable tool for growers to monitor and manage water stress and irrigation scheduling. Clipping has been demonstrated to be a viable harvest technique, and would allow growers an early return on their investment, plus it would delay the cost of stand reestablishment. Increasing salinity results in decreased biomass and rubber yield. Guayule transplants have been shown to maintain production at salinities up to 4.5–4.6 dS/m. Pendimethalin is safe for preemergence weed control in transplanted guayule. A Special Local Needs registration for pendimethalin is in place for the preemergence control of annual grasses and broadleaf weeds in Arizona. No postemergence treatments have been successful except during guayule's dormant period. Several preemergence herbicides are safe for weed control in direct-seeded guayule. However, no treatments are currently approved.

Sustainable management regimes for Europe's forests — a projection with EFISCEN until 2050

In Europe, forest policy discussions are moving towards a European Union-wide strategy. This will further intensify the relations between European countries in the field of forests and forest management. European-wide forest planning and decision-making require that policy makers have insight into the long-term development of European forests under alternative regimes. The European Forest Information Scenario Model (EFISCEN) was used to make projections of the development of the European forests under four scenarios: (1) business as usual; (2) EFISCEN European timber trend studies (ETTS); (3) maximum sustainable production; and (4) multifunctional management. The simulations were carried out for 30 countries individually, i.e. harmonized scenarios were run, but the special circumstances and demands that play a role in each country were taken into account. The simulations covered 139.2 million ha increasing to 143 million ha in 2050. The initial year varied per country, but was mostly in the region of 1990. The average age of European forests was 57 years in 1990 with a mean growing stock of 142 m 3 ha −1. The results showed that the future European total fellings may vary between a stable amount of 400 million m 3 year −1 in the ‘business as usual’ scenario to 647 million m 3 year −1 in the ‘maximum sustainable production’ scenario. The other two scenarios incorporated a 9% gradual increase in fellings over the first 30 years of the simulation period (i.e. 0.3% year −1). The average growing stock will rise to approximately 250 m 3 ha −1 in 2050, with the exception being the ‘maximum sustainable production’ scenario, in which the growing remains at approximately 137 m 3 ha −1. The average net annual increment remains at approximately 5 m 3 ha −1 year −1 throughout the simulation period, almost irrespective of the scenario. In the multifunctional scenario, special attention was paid to nature values by increasing the area of strict reserves from 4 million ha in 1990 to 12.3 million ha in 2050 (8.6% of the total forest area). The assumed increase in fellings of 0.3% year −1 appeared possible in combination with this area of reserves. The simulations showed that growing stock development and increment development differed very much for each country separately per scenario. Therefore, the results show a strong need for maintaining the national diversity that constitutes European forestry within harmonized European-wide forest management strategies. In this article, we address what the consequences of each scenario are for wood production, biodiversity, and environmental functions of the forest. The results provide policy makers with a challenge on whether to intervene in the ongoing trend of build-up of growing stock and whether to choose for biodiversity, for increased use of domestically produced wood products, or a combination of these, but spatially separated.