Conventional harvesting problems for natural resources often assume physiological homogeneity of the body length/weight among individuals. However, such assumptions generally are not valid in real-world problems, where heterogeneity plays an essential role in the planning of biological resource harvesting. Furthermore, it is difficult to observe heterogeneity directly from the available data. This paper presents a novel optimal control framework for the cost-efficient harvesting of biological resources for application in fisheries management. The heterogeneity is incorporated into the resource dynamics, which is the population dynamics in this case, through a probability density that can be distorted from reality. Subsequently, the distortion, which is the model uncertainty, is penalized through a divergence, leading to a nonstandard dynamic differential game wherein the Hamilton–Jacobi–Bellman–Isaacs (HJBI) equation has a unique nonlinear partial differential term. Here, the existence and uniqueness results of the HJBI equation are presented along with an explicit monotone finite difference method. Finally, the proposed optimal control is applied to a harvesting problem with recreationally, economically, and ecologically important fish species using collected field data.
{"title":"Optimal harvesting policy for biological resources with uncertain heterogeneity for application in fisheries management","authors":"Hidekazu Yoshioka","doi":"10.1111/nrm.12394","DOIUrl":"https://doi.org/10.1111/nrm.12394","url":null,"abstract":"Conventional harvesting problems for natural resources often assume physiological homogeneity of the body length/weight among individuals. However, such assumptions generally are not valid in real-world problems, where heterogeneity plays an essential role in the planning of biological resource harvesting. Furthermore, it is difficult to observe heterogeneity directly from the available data. This paper presents a novel optimal control framework for the cost-efficient harvesting of biological resources for application in fisheries management. The heterogeneity is incorporated into the resource dynamics, which is the population dynamics in this case, through a probability density that can be distorted from reality. Subsequently, the distortion, which is the model uncertainty, is penalized through a divergence, leading to a nonstandard dynamic differential game wherein the Hamilton–Jacobi–Bellman–Isaacs (HJBI) equation has a unique nonlinear partial differential term. Here, the existence and uniqueness results of the HJBI equation are presented along with an explicit monotone finite difference method. Finally, the proposed optimal control is applied to a harvesting problem with recreationally, economically, and ecologically important fish species using collected field data.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"25 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139656084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the single-species literature, it is widely acknowledged that conserving young fish for future harvesting is beneficial. This finding holds great significance in fisheries economics and has garnered substantial attention over the years. In this study, a full-blown age-structured predator–prey model is developed and used to demonstrate that multispecies considerations may shift the optimal selection of predators towards smaller individuals, providing valuable counteractive insights. These new results offer a fresh perspective highly relevant to regulation and choice of selectivity patterns.
{"title":"Beyond age-structured single-species management: Optimal harvest selectivity in the face of predator–prey interactions","authors":"Rasmus Noss Bang, Stein Ivar Steinshamn","doi":"10.1111/nrm.12393","DOIUrl":"https://doi.org/10.1111/nrm.12393","url":null,"abstract":"In the single-species literature, it is widely acknowledged that conserving young fish for future harvesting is beneficial. This finding holds great significance in fisheries economics and has garnered substantial attention over the years. In this study, a full-blown age-structured predator–prey model is developed and used to demonstrate that multispecies considerations may shift the optimal selection of predators towards smaller individuals, providing valuable counteractive insights. These new results offer a fresh perspective highly relevant to regulation and choice of selectivity patterns.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"27 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The urban agglomeration in the middle reaches of the Yangtze river (MYRUA) is the second largest national urban agglomeration in China, with an excellent ecological foundation. As the construction of urban agglomerations accelerated towards both extension and connotation, land prices of various cities rose, and the contradiction in the demand and utilization of land resources became acute. Therefore, exploring the spatiotemporal evolution and driving mechanisms of land green utilization efficiency within MYRUA had positive significance. This article focused on 28 prefecture-level cities in the MYRUA and measured their urban land green use efficiency (ULGUE) from 2006 to 2018 using the super slack-based measure model with undesirable output (Super-SBM-U). Then, the improved Fixed Malmquist–Luenberger index was developed to improve the accuracy of dynamic efficiency analysis. Further, the internal and external driving factors were explored using the index decomposition and the spatial error model with fixed effects. The results showed that the land use mode of the urban agglomeration in the middle reaches of the Yangtze River was relatively green, but efficiency gaps still existed. Although the green total factor productivity of the whole cluster has improved by 3.30% a year on average, the excessive pursuit of technological innovation has led to the stagnation of urban land management in various cities, and there are numerous inherent contradictions in urban development. But at the same time, feasible economic development directions, industrial upgrading, high-quality employees, land marketization, and positive environmental behaviors are conducive to the green and sustainable development of ULGUE. This article depicted the internal land use characteristics of the MYRUA from the perspective of spatiotemporal evolution and efficiency, providing a theoretical reference for the green development and coordinated management of urban agglomeration land.
{"title":"How does the green efficiency of urban land use evolve in the urban agglomeration of China's middle Yangtze river?","authors":"Jiaxuan Hong, Yanling Mao","doi":"10.1111/nrm.12392","DOIUrl":"https://doi.org/10.1111/nrm.12392","url":null,"abstract":"The urban agglomeration in the middle reaches of the Yangtze river (MYRUA) is the second largest national urban agglomeration in China, with an excellent ecological foundation. As the construction of urban agglomerations accelerated towards both extension and connotation, land prices of various cities rose, and the contradiction in the demand and utilization of land resources became acute. Therefore, exploring the spatiotemporal evolution and driving mechanisms of land green utilization efficiency within MYRUA had positive significance. This article focused on 28 prefecture-level cities in the MYRUA and measured their urban land green use efficiency (ULGUE) from 2006 to 2018 using the super slack-based measure model with undesirable output (Super-SBM-U). Then, the improved Fixed Malmquist–Luenberger index was developed to improve the accuracy of dynamic efficiency analysis. Further, the internal and external driving factors were explored using the index decomposition and the spatial error model with fixed effects. The results showed that the land use mode of the urban agglomeration in the middle reaches of the Yangtze River was relatively green, but efficiency gaps still existed. Although the green total factor productivity of the whole cluster has improved by 3.30% a year on average, the excessive pursuit of technological innovation has led to the stagnation of urban land management in various cities, and there are numerous inherent contradictions in urban development. But at the same time, feasible economic development directions, industrial upgrading, high-quality employees, land marketization, and positive environmental behaviors are conducive to the green and sustainable development of ULGUE. This article depicted the internal land use characteristics of the MYRUA from the perspective of spatiotemporal evolution and efficiency, providing a theoretical reference for the green development and coordinated management of urban agglomeration land.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"36 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138540808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There is competition for land between Maasai pastoralists and the park agency in the Serengeti ecosystem. The park agency wants to use the land for wildlife conservation while the pastoralist community wants to use it for livestock grazing. Predatory wildlife kills livestock while herbivorous wildlife competes with livestock for water and grazing. In retaliation, the Maasai hunt predators and grazers to protect their livestock and also to supply the black market for wildlife products. With both the Maasai and animal populations growing, increased conflicts are inevitable. This paper develops a bioeconomic model with three animal species to analyse the optimal combination of pastoral activities and wildlife conservation in the Serengeti ecosystem. Using Pontryagin's maximum principle, the market problem for each agent is optimized and compared to the social planner's outcome. Results show that the market solutions are suboptimal because of negative externalities affecting both agents and inadequate regard to biodiversity conservation values. Mathematical simulations of the bioeconomic model are used to generate a solution in which the Maasai pastoralists and park agency can optimally share the land for their mutual benefit. The policy implication is that the government should establish an independent regulatory institution with a primary mandate of balancing the contested socioeconomic and ecological needs of stakeholders in prime ecosystems such as the Serengeti.
{"title":"The optimal combination of pastoral activities and wildlife conservation in the Serengeti ecosystem","authors":"Gerald Kibira, Edwin Muchapondwa, Herbert Ntuli","doi":"10.1111/nrm.12391","DOIUrl":"https://doi.org/10.1111/nrm.12391","url":null,"abstract":"There is competition for land between Maasai pastoralists and the park agency in the Serengeti ecosystem. The park agency wants to use the land for wildlife conservation while the pastoralist community wants to use it for livestock grazing. Predatory wildlife kills livestock while herbivorous wildlife competes with livestock for water and grazing. In retaliation, the Maasai hunt predators and grazers to protect their livestock and also to supply the black market for wildlife products. With both the Maasai and animal populations growing, increased conflicts are inevitable. This paper develops a bioeconomic model with three animal species to analyse the optimal combination of pastoral activities and wildlife conservation in the Serengeti ecosystem. Using Pontryagin's maximum principle, the market problem for each agent is optimized and compared to the social planner's outcome. Results show that the market solutions are suboptimal because of negative externalities affecting both agents and inadequate regard to biodiversity conservation values. Mathematical simulations of the bioeconomic model are used to generate a solution in which the Maasai pastoralists and park agency can optimally share the land for their mutual benefit. The policy implication is that the government should establish an independent regulatory institution with a primary mandate of balancing the contested socioeconomic and ecological needs of stakeholders in prime ecosystems such as the Serengeti.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"127 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138540755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Biodiversity offsets (BOs) are increasingly used as economic instruments to manage biodiversity and ecosystem services in the context of economic development. This study investigates the sustainability conditions of BOs. It focuses especially on both the timing and pricing of BOs in development-offset projects. To address this issue, a minimal time control model is proposed, allowing a dynamic and multicriteria approach to be combined through both ecological and economic targets. We rely here on no net loss (NNL) and positive net present value (NPV) goals. In particular, we focus on an offset marginal price, called offset sustainability price (OSP), which equalizes the NNL and payback times. We prove analytically how this OSP pricing corresponds to a win–win solution in terms of ecological-economic synergy. We also show that this OSP pricing can be very high compared to the project rate of return, particularly when the biodiversity loss is high. More globally, a static comparative analysis shows the extent to which the economic and biodiversity parameters impact the OSP. Finally, a numerical application related to mangroves and aquaculture in Madagascar illustrates the analytical findings. For this case study, we argue that the current BO price is underestimated.
{"title":"When profitability meets conservation objectives through biodiversity offsets","authors":"Celine Huber, Luc Doyen, Sylvie Ferrari","doi":"10.1111/nrm.12389","DOIUrl":"https://doi.org/10.1111/nrm.12389","url":null,"abstract":"Biodiversity offsets (BOs) are increasingly used as economic instruments to manage biodiversity and ecosystem services in the context of economic development. This study investigates the sustainability conditions of BOs. It focuses especially on both the timing and pricing of BOs in development-offset projects. To address this issue, a minimal time control model is proposed, allowing a dynamic and multicriteria approach to be combined through both ecological and economic targets. We rely here on no net loss (NNL) and positive net present value (NPV) goals. In particular, we focus on an offset marginal price, called offset sustainability price (OSP), which equalizes the NNL and payback times. We prove analytically how this OSP pricing corresponds to a win–win solution in terms of ecological-economic synergy. We also show that this OSP pricing can be very high compared to the project rate of return, particularly when the biodiversity loss is high. More globally, a static comparative analysis shows the extent to which the economic and biodiversity parameters impact the OSP. Finally, a numerical application related to mangroves and aquaculture in Madagascar illustrates the analytical findings. For this case study, we argue that the current BO price is underestimated.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"10 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138540756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The concept of maximum sustainable yield (MSY), and the underlying Schaefer model, remain relevant in fisheries management today in spite of past difficulties. However, this model is often applied without the consideration of the spatial structure or dynamics of fishing activities. We expand the Schaefer model to account for multiple fishing sites and fishing activities (effort) that follow an ideal free distribution (IFD, a form of Nash equilibrium) driven by exploitation. We explore this conceptual model using both analytical and numerical solutions. MSY across the fishery is unaffected by the spatial structure when fishing is allocated independently within sites. However, in other cases IFD effort dynamics depress MSY and modify the values of associated reference points. The game theoretic aspect of fleet dynamics should be considered in the use of MSY as a management reference point or during the application of the Schaefer model to data-limited fisheries.
{"title":"Maximum sustainable yield as a reference point in the presence of fishing effort that follows an ideal free distribution","authors":"Darren M. Gillis, Jonah Koscielny, Benjamin Blanz","doi":"10.1111/nrm.12390","DOIUrl":"https://doi.org/10.1111/nrm.12390","url":null,"abstract":"The concept of maximum sustainable yield (MSY), and the underlying Schaefer model, remain relevant in fisheries management today in spite of past difficulties. However, this model is often applied without the consideration of the spatial structure or dynamics of fishing activities. We expand the Schaefer model to account for multiple fishing sites and fishing activities (effort) that follow an ideal free distribution (IFD, a form of Nash equilibrium) driven by exploitation. We explore this conceptual model using both analytical and numerical solutions. MSY across the fishery is unaffected by the spatial structure when fishing is allocated independently within sites. However, in other cases IFD effort dynamics depress MSY and modify the values of associated reference points. The game theoretic aspect of fleet dynamics should be considered in the use of MSY as a management reference point or during the application of the Schaefer model to data-limited fisheries.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138540758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yonky Indrajaya, Hans‐Peter Weikard, Frits Mohren, Edwin van der Werf
Forests play an essential role in climate change mitigation by absorbing carbon dioxide from the atmosphere and storing carbon in biomass. Carbon sequestration can be increased by the extension of rotation cycles in existing plantation forests. This study examines the cost‐effectiveness of the remuneration scheme employed by Verified Carbon Standard (VCS), a commonly used carbon accounting method based on the average amount of carbon stored in the forest. We compare the net present value of carbon remuneration under VCS with that of a scheme that remunerates actual carbon storage in each year which we call “current carbon accounting.” We use data for an Acacia mangium plantation in Indonesia where the forestry sector is expected to contribute more than half of the reductions of carbon emissions according to Indonesia's Nationally Determined Contribution (NDC) under the Paris Agreement. For our baseline scenario, we find, first, that the payments needed to incentivise additional carbon storage under VCS are considerably higher than under current carbon accounting. Second, the inefficiency is more pronounced at lower discount rates. Third, recent prices reported for VCS forest credits are not sufficient to incentivise forest managers to lengthen the forest rotation in Indonesian plantation forests.
{"title":"Paying for forest carbon: Cost‐effectiveness of the Verified Carbon Standard (VCS) remuneration scheme","authors":"Yonky Indrajaya, Hans‐Peter Weikard, Frits Mohren, Edwin van der Werf","doi":"10.1111/nrm.12387","DOIUrl":"https://doi.org/10.1111/nrm.12387","url":null,"abstract":"Forests play an essential role in climate change mitigation by absorbing carbon dioxide from the atmosphere and storing carbon in biomass. Carbon sequestration can be increased by the extension of rotation cycles in existing plantation forests. This study examines the cost‐effectiveness of the remuneration scheme employed by Verified Carbon Standard (VCS), a commonly used carbon accounting method based on the average amount of carbon stored in the forest. We compare the net present value of carbon remuneration under VCS with that of a scheme that remunerates actual carbon storage in each year which we call “current carbon accounting.” We use data for an Acacia mangium plantation in Indonesia where the forestry sector is expected to contribute more than half of the reductions of carbon emissions according to Indonesia's Nationally Determined Contribution (NDC) under the Paris Agreement. For our baseline scenario, we find, first, that the payments needed to incentivise additional carbon storage under VCS are considerably higher than under current carbon accounting. Second, the inefficiency is more pronounced at lower discount rates. Third, recent prices reported for VCS forest credits are not sufficient to incentivise forest managers to lengthen the forest rotation in Indonesian plantation forests.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"32 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135819333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract A cornerstone of conservation policy for endangered species subject to illegal harvest involves estimating their population and offtake numbers. Census enumerations are expensive to conduct on nationwide scales, especially in resource‐constrained countries housing such species. Resource and data limitations necessitate the estimation of population counts. The effect of poaching on species recruitment is often ignored in scientific population projections. Estimation of population counts should account for the interactive feedback between harvest and recruitment. Data on tiger population sizes and poaching from 51 reserves in India between 1994 and 2022 were obtained to calibrate a coupled ecological‐economic model of tiger population dynamics and poaching. Cobb–Douglas harvest functions with differing degrees of concavity and scale economies are used to characterize the economics of poaching. Population dynamics are evaluated using exponential and critical depensation growth functions. The predictive abilities of linked models and their parameter parsimony are evaluated using information criteria. Poaching is shown to substantially affect recruitment dynamics and is best characterized by a Schaefer function coupled with critical depensation growth. This paper provides a novel perspective of the interaction between tiger poaching and population dynamics in India. A systematic understanding of coupled ecological‐economic processes would improve the management of high‐value endangered species.
{"title":"Evaluating feedback dynamics between poaching and population with an application to Indian tigers","authors":"Adrian A. Lopes","doi":"10.1111/nrm.12386","DOIUrl":"https://doi.org/10.1111/nrm.12386","url":null,"abstract":"Abstract A cornerstone of conservation policy for endangered species subject to illegal harvest involves estimating their population and offtake numbers. Census enumerations are expensive to conduct on nationwide scales, especially in resource‐constrained countries housing such species. Resource and data limitations necessitate the estimation of population counts. The effect of poaching on species recruitment is often ignored in scientific population projections. Estimation of population counts should account for the interactive feedback between harvest and recruitment. Data on tiger population sizes and poaching from 51 reserves in India between 1994 and 2022 were obtained to calibrate a coupled ecological‐economic model of tiger population dynamics and poaching. Cobb–Douglas harvest functions with differing degrees of concavity and scale economies are used to characterize the economics of poaching. Population dynamics are evaluated using exponential and critical depensation growth functions. The predictive abilities of linked models and their parameter parsimony are evaluated using information criteria. Poaching is shown to substantially affect recruitment dynamics and is best characterized by a Schaefer function coupled with critical depensation growth. This paper provides a novel perspective of the interaction between tiger poaching and population dynamics in India. A systematic understanding of coupled ecological‐economic processes would improve the management of high‐value endangered species.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135980520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Systems of whole‐stand yield models facilitate projections of forest attributes, but their inputs may be difficult to measure accurately. This study conducted sensitivity analyses to examine the effect of systematic and stochastic measurement errors on outputs from a representative system of equations. Simulated error was added to explanatory variables stand age, site index, or both. Results showed that large systematic error in one variable tended to produce moderate to large percent changes in all models, particularly the height and volume equations (often >50% change). Systematic error in both variables amplified this effect, especially for young, less productive stands. Stochastic error dramatically increased estimate variability (some relative standard errors >50%), particularly in the height and volume models at young ages and low site indices. These results suggest that measurement error may considerably alter projections and increase uncertainty when using whole‐stand yield models, highlighting the need for careful crew training.
{"title":"Measurement error effects on estimates from linear and nonlinear regression whole‐stand yield models","authors":"John M. Zobel","doi":"10.1111/nrm.12384","DOIUrl":"https://doi.org/10.1111/nrm.12384","url":null,"abstract":"Systems of whole‐stand yield models facilitate projections of forest attributes, but their inputs may be difficult to measure accurately. This study conducted sensitivity analyses to examine the effect of systematic and stochastic measurement errors on outputs from a representative system of equations. Simulated error was added to explanatory variables stand age, site index, or both. Results showed that large systematic error in one variable tended to produce moderate to large percent changes in all models, particularly the height and volume equations (often >50% change). Systematic error in both variables amplified this effect, especially for young, less productive stands. Stochastic error dramatically increased estimate variability (some relative standard errors >50%), particularly in the height and volume models at young ages and low site indices. These results suggest that measurement error may considerably alter projections and increase uncertainty when using whole‐stand yield models, highlighting the need for careful crew training.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42351384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reza Chamani, S. Sadeghi, Somayeh Zare, Hengameh Shekohideh, Azam Mumzaei, Hamed Amini, Laila Hemmati, R. Zarei
Today, watersheds have changed under the influence of various environmental and human factors, and their expected performance has decreased in terms of meeting human needs, providing natural responses, and reducing environmental risks. However, evaluating health status and its impact on various factors has not been given enough attention. To this end, an attempt has been made to evaluate the health and ecological security of the sub‐watersheds of the Sharghonj Watershed using the pressure‐state‐response approach emphasizing flood‐related issues in the region. Towards that, 21 preliminary hydrological, anthropogenic, natural, and climatic criteria were selected. The preliminary variables were then finalized based on the results of the collinearity test and the data availability. The final variables were appropriately allocated to pressure, state, and response indices, and associated health and ecological security indices were determined at the sub‐watershed scale. The results showed that the pressure, state, and response ranged from 0.56 to 0.86, 0.46 to 0.84, and 0.35 to 0.96, respectively. Health and ecological security also varied from 0.53 to 0.83 and 0.27 to 1.01 in different sub‐watersheds. Eventually, the weighted mean pressure, state, and response indices for the Sharghonj Watershed were 0.72, 0.67, and 0.73, respectively. The weighted mean health and ecological security indices were 0.70 and 0.68, respectively. The research results indicated that the dynamic of various variables related to floods considerably affects the health of the Sharghonj Watershed. It could be concluded from the results that the Sharghonj Watershed is highly flood‐susceptible, whose health and ecological security status was mainly controlled by the damages due to the destruction of residences and orchards by floods in the past years. The results of the current study provide an appropriate roadmap to the decision makers and planners for the better management of the watershed resources in the region through allocating adequate financial support and implementation measures to priority sub‐watersheds.This article is protected by copyright. All rights reserved.
{"title":"Flood‐Oriented Watershed Health and Ecological Security Conceptual Modeling using PSR Approach for the Sharghonj Watershed, South Khorasan Province, Iran","authors":"Reza Chamani, S. Sadeghi, Somayeh Zare, Hengameh Shekohideh, Azam Mumzaei, Hamed Amini, Laila Hemmati, R. Zarei","doi":"10.1111/nrm.12385","DOIUrl":"https://doi.org/10.1111/nrm.12385","url":null,"abstract":"Today, watersheds have changed under the influence of various environmental and human factors, and their expected performance has decreased in terms of meeting human needs, providing natural responses, and reducing environmental risks. However, evaluating health status and its impact on various factors has not been given enough attention. To this end, an attempt has been made to evaluate the health and ecological security of the sub‐watersheds of the Sharghonj Watershed using the pressure‐state‐response approach emphasizing flood‐related issues in the region. Towards that, 21 preliminary hydrological, anthropogenic, natural, and climatic criteria were selected. The preliminary variables were then finalized based on the results of the collinearity test and the data availability. The final variables were appropriately allocated to pressure, state, and response indices, and associated health and ecological security indices were determined at the sub‐watershed scale. The results showed that the pressure, state, and response ranged from 0.56 to 0.86, 0.46 to 0.84, and 0.35 to 0.96, respectively. Health and ecological security also varied from 0.53 to 0.83 and 0.27 to 1.01 in different sub‐watersheds. Eventually, the weighted mean pressure, state, and response indices for the Sharghonj Watershed were 0.72, 0.67, and 0.73, respectively. The weighted mean health and ecological security indices were 0.70 and 0.68, respectively. The research results indicated that the dynamic of various variables related to floods considerably affects the health of the Sharghonj Watershed. It could be concluded from the results that the Sharghonj Watershed is highly flood‐susceptible, whose health and ecological security status was mainly controlled by the damages due to the destruction of residences and orchards by floods in the past years. The results of the current study provide an appropriate roadmap to the decision makers and planners for the better management of the watershed resources in the region through allocating adequate financial support and implementation measures to priority sub‐watersheds.This article is protected by copyright. All rights reserved.","PeriodicalId":49778,"journal":{"name":"Natural Resource Modeling","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42205729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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