Ecosystem Simulation Model Research Articles

Higher temperature variability reduces temperature sensitivity of vegetation growth in Northern Hemisphere

AbstractInterannual air temperature variability has changed over some regions in Northern Hemisphere (NH), accompanying with climate warming. However, whether and to what extent it regulates the interannual sensitivity of vegetation growth to temperature variability (i.e., interannual temperature sensitivity)—one central issue in understanding and predicting the responses of vegetation growth to changing climate—still remains poorly quantified and understood. Here we quantify the relationships between the interannual temperature sensitivity of mean growing‐season (April–October) normalized difference vegetation index (NDVI) and ecosystem model simulations of gross primary productivity (GPP), and variability in mean growing‐season temperature for forest, shrub, and grass over NH. We find that higher interannual variability in mean growing‐season temperature leads to consistent decrease in interannual temperature sensitivity of mean growing‐season NDVI among all vegetation types but not in model simulations of GPP. Drier condition associates with ~130 ± 150% further decrease in interannual temperature sensitivity of mean growing‐season NDVI by temperature variability in forest and shrub. These results illustrate that varying temperature variability can significantly regulate the interannual temperature sensitivity of vegetation growth over NH, interacted with drought variability and nonlinear responses of photosynthesis to temperature. Our findings call for an improved characterization of the nonlinear effects of temperature variability on vegetation growth within global ecosystem models.

Ecosystem modeling in the Gulf of Mexico: current status and future needs to address ecosystem-based fisheries management and restoration activities

Many ecosystem-based fisheries management (EBFM) measures and restoration projects have been implemented to address the stressors that have negatively affected the United States (U.S.) Gulf of Mexico (GOM). Ecosystem simulation models are useful tools for tackling EBFM and restoration questions. Here, we review the current status of ecosystem modeling efforts for the U.S. GOM and whole GOM large marine ecosystem and identify future needs to address EBFM and restoration in these regions. Existing ecosystem models of the GOM are diverse, ranging from simple conceptual and qualitative models to biogeochemical-based end-to-end models and coupled and hybrid model platforms. Many models have focused on understanding the structure and functioning of GOM ecosystems and the impacts of EBFM measures such as bycatch reduction strategies and marine protected areas. By contrast, a small number of ecosystem models have been used specifically to address the other EBFM issues of the GOM and to assess restoration efforts (e.g., marsh restoration). The demands for EBFM and state and gulf-wide restoration activities will both be increasing in the GOM. Therefore, there is a critical need to better employ and enhance existing ecosystem models of the GOM, and to develop new ecosystem models, to more comprehensively address the different EBFM and restoration needs in the region. We provide suggestions to facilitate this endeavor. The development of consistent libraries of ecosystem models and gap analyses such as ours will help fisheries scientists to effectively tackle specific resource management questions in the different marine regions of the world.

Net climate impacts and economic profitability of forest biomass production and utilization in fossil fuel and fossil-based material substitution under alternative forest management

We studied net climate impacts and economic profitability of the production and utilization of biomass from a Norway spruce (Picea abies L. Karst) stand under alternative forest management in Finnish boreal conditions over 60–100-year rotations. The work employed ecosystem model simulations and a life cycle assessment tool as integrated. The net climate impact of biomass referred to the difference in annual net CO2 exchange between the biosystem and fossil system. Sawn wood, pulp, energy biomass and processing waste substituted for concrete/steel, plastic and coal/oil. In the biosystem, ‘business as usual’ (baseline) and alternative management (maintaining 10–30% higher or lower stocking than the baseline, and/or nitrogen fertilization, and harvesting intensity) were used. The fossil system considered baseline and unthinning as reference management and also net ecosystem CO2 exchange as excluded. We found that using timber and energy biomass generated 32–40% higher net climate impacts compared to using only timber. Generally, harvesting of energy biomass increased the economic profitability but the net climate impacts of biomass were highest over 80–100-year rotations. Maintaining higher stocking in thinning and fertilization generally enhanced net climate impacts, but maintaining up to 20% higher stocking and both energy biomass and timber production increased both net climate impacts and economic profitability. The baseline as a reference produced higher climate benefits compared to unthinning regime. The increased production and use of sawn wood with energy biomass appeared the best option for long-term mitigation, since they enhanced both net climate impacts compared to the fossil system and economic returns.

Current and future carbon budget at Takayama site, Japan, evaluated by a regional climate model and a process-based terrestrial ecosystem model.

Accurate projection of carbon budget in forest ecosystems under future climate and atmospheric carbon dioxide (CO2) concentration is important to evaluate the function of terrestrial ecosystems, which serve as a major sink of atmospheric CO2. In this study, we examined the effects of spatial resolution of meteorological data on the accuracies of ecosystem model simulation for canopy phenology and carbon budget such as gross primary production (GPP), ecosystem respiration (ER), and net ecosystem production (NEP) of a deciduous forest in Japan. Then, we simulated the future (around 2085) changes in canopy phenology and carbon budget of the forest by incorporating high-resolution meteorological data downscaled by a regional climate model. The ecosystem model overestimated GPP and ER when we inputted low-resolution data, which have warming biases over mountainous landscape. But, it reproduced canopy phenology and carbon budget well, when we inputted high-resolution data. Under the future climate, earlier leaf expansion and delayed leaf fall by about 10 days compared with the present state was simulated, and also, GPP, ER and NEP were estimated to increase by 25.2%, 23.7% and 35.4%, respectively. Sensitivity analysis showed that the increase of NEP in June and October would be mainly caused by rising temperature, whereas that in July and August would be largely attributable to CO2 fertilization. This study suggests that the downscaling of future climate data enable us to project more reliable carbon budget of forest ecosystem in mountainous landscape than the low-resolution simulation due to the better predictions of leaf expansion and shedding.

Comprehensive synthesis of spatial variability in carbon flux across monsoon Asian forests

Forest ecosystems sequester large amounts of atmospheric CO2, and the contribution from forests in Asia is not negligible. Previous syntheses of carbon fluxes in Asian ecosystems mainly employed estimates of eddy covariance measurements, net ecosystem production (NEP), gross primary production (GPP), and ecosystem respiration (RE); however, to understand the variability within carbon cycles, fluxes such as autotropic respiration (AR), net primary production (NPP), litterfall, heterotrophic respiration (HR), and soil respiration (SR) need to be analyzed comprehensively in conjunction with NEP, GPP, and RE. Here we investigated the spatial variability of component fluxes of carbon balance (GPP, AR, NPP, litterfall, HR, SR, and RE) in relation to climate factors, between carbon fluxes, and to NEP using observations compiled from the literature for 22 forest sites in monsoon Asia. We found that mean annual temperature (MAT) largely relates to the spatial variability of component fluxes in monsoon Asian forests, with stronger positive effect in the mid–high latitude forests than in the low latitude forests, but even stronger relationships were identified between component fluxes regardless of regions. This finding suggests that the spatial variability of carbon fluxes in monsoon Asia is certainly influenced by climatic factors such as MAT, but that the overall spatial variability of AR, NPP, litterfall, HR, SR, and RE is rather controlled by that of productivity (i.e., GPP). Furthermore, component fluxes of the mid–high and low latitude forests showed positive and negative relationships, respectively, with NEP. Further investigation identified a common spatial variability in NEP and annual aboveground biomass changes with respect to GPP. The relationship between GPP and NEP in the mid–high latitudes implies that productivity and net carbon sequestration increase simultaneously in boreal and temperate forests. Meanwhile, the relationship between GPP and NEP in the low latitudes indicates that net carbon sequestration decreases with productivity, potentially due to the regional contrast in nitrogen depositions and stand age within sub-tropical and tropical forests; however, it requires further data syntheses or modelling investigations for confirmation of its general validity. These unique features of monsoon Asian forest carbon fluxes provide useful information for improving ecosystem model simulations, which still differ in their predictability of carbon flux variability.

Summer profundal hypoxia determines the coupling of methanotrophic production and the pelagic food web in a subtropical reservoir

Summary We investigated how profundal redox conditions determine the inter‐annual variation in methane oxidising bacteria (MOB) contribution to zooplankton production in a deep subtropical reservoir. Two hydrological regimes which affect MOB activity are considered: (i) reduced MOB activity resulting from high profundal oxygen saturation promoted by water column disturbance during the period of summer stratification; and (ii) increased MOB activity due to high profundal oxygen saturation during winter mixing. Four years of field stable‐isotope analyses revealed that oxygen saturation of profundal waters during summer stratification was negatively correlated with winter MOB contribution. This relationship is consistent with our theoretical ecosystem modelling. Although the ecosystem model simulation predicted positive effects of profundal oxygen supply during winter mixing on MOB contribution, the stable isotope mixing model indicated that the effects were secondary. Winter oxygen supply did not enhance MOB activity when methane accumulation during the preceding summer was low. Our findings suggest that summer profundal hypoxia plays the primary role in determining methanotrophic food‐web activity and methane‐derived carbon cycling in deep lakes.

Carbon content and climate variability drive global soil bacterial diversity patterns

AbstractDespite the vital role of microorganisms for ecosystem functioning and human welfare, our understanding of their global diversity and biogeographical patterns lags significantly behind that of plants and animals. We conducted a meta‐analysis including ~600 soil samples from all continents to evaluate the biogeographical patterns and drivers of bacterial diversity in terrestrial ecosystems at the global scale. Similar to what has been found with plants and animals, the diversity of soil bacteria in the Southern Hemisphere decreased from the equator to Antarctica. However, soil bacteria showed similar levels of diversity across the Northern Hemisphere. The composition of bacterial communities followed dissimilar patterns between hemispheres, as the Southern and Northern Hemispheres were dominated by Actinobacteria and Acidobacteria, respectively. However, Proteobacteria was co‐dominant in both hemispheres. Moreover, we found a decrease in soil bacterial diversity with altitude. Climatic features (e.g., high diurnal temperature range and low temperature) were correlated with the lower diversity found at high elevations, but geographical gradients in soil total carbon and species turnover were important drivers of the observed latitudinal patterns. We thus found both parallels and differences in the biogeographical patterns of aboveground vs. soil bacterial diversity. Our findings support previous studies that highlighted soil pH, spatial influence, and organic matter as important drivers of bacterial diversity and composition. Furthermore, our results provide a novel integrative view of how climate and soil factors influence soil bacterial diversity at the global scale, which is critical to improve ecosystem and earth system simulation models and for formulating sustainable ecosystem management and conservation policies.

Using forest ecosystem simulation model EFIMOD in planning uneven-aged forest management

Uneven-aged forest management is suggested to be a sustainable management alternative in boreal forests, but knowledge on applicable harvest intensities is very limited as majority of the studies has focused on even-aged management practices. The ecosystem model EFIMOD was used to assess the effect of selection cuttings on ecosystem production, carbon sequestration and volume increment in spruce stands. The model was calibrated and validated against experimental data from 20 permanent forest plots in southern Finland where stand responses to uneven-aged management had been monitored for 25years. The simulated scenarios started with planting trees on bare land, simulation of first decades according to even-aged management, and a subsequent transformation into uneven-aged stand structure and management. Simulated selection cutting scenarios contained variations of both harvest interval (10–30years) and postharvest stand density (basal area 8–16m2ha−1). We hypothesized that longer harvest intervals and higher post-harvest basal areas will positively affect the net ecosystem production, nitrogen use efficiency, and forest carbon sequestration. The results presented here are for a period of 90years. Simulations showed that net ecosystem production (NEP) increased from 0.25 to 0.5kgm−2a−1 of carbon with longer harvest intervals and higher postharvest density, and was generally less than that at undisturbed development. Nitrogen use efficiency (NUE) varied from 100kg NPP per kg consumed N for heavy cuttings to 300kg NPP per kg consumed N for light removal of trees. Changes in soil carbon stocks were negative for most scenarios (5–20% decline in terms of total soil C), and the decline was most pronounced with lowest postharvest density and short harvest intervals. The volume of harvested timber was between 320 and 400m3ha−1 for a 60-year period. Longer harvest intervals resulted in increased timber production. Stem volume growth (5–7m3ha−1a−1) was equally affected by both harvesting parameters. The cumulative volume of deadwood of 80–120m3ha−1 was substantially higher with the longest harvest interval (30years) than with the shorter alternatives where it comprised 40–60m3ha−1. The simulations provide novel results on different harvesting options for uneven-aged forest management of boreal Norway spruce stands. These results fill a gap in knowledge on ecosystem responses to alternative management regimes and support the development of sustainable management practices.

Stoichiometry of microbial carbon use efficiency in soils

AbstractThe carbon use efficiency (CUE) of microbial communities partitions the flow of C from primary producers to the atmosphere, decomposer food webs, and soil C stores. CUE, usually defined as the ratio of growth to assimilation, is a critical parameter in ecosystem models, but is seldom measured directly in soils because of the methodological difficulty of measuring in situ rates of microbial growth and respiration. Alternatively, CUE can be estimated indirectly from the elemental stoichiometry of organic matter and microbial biomass, and the ratios of C to nutrient‐acquiring ecoenzymatic activities. We used this approach to estimate and compare microbial CUE in >2000 soils from a broad range of ecosystems. Mean CUE based on C:N stoichiometry was 0.269 ± 0.110 (mean ± SD). A parallel calculation based on C:P stoichiometry yielded a mean CUE estimate of 0.252 ± 0.125. The mean values and frequency distributions were similar to those from aquatic ecosystems, also calculated from stoichiometric models, and to those calculated from direct measurements of bacterial and fungal growth and respiration. CUE was directly related to microbial biomass C with a scaling exponent of 0.304 (95% CI 0.237–0.371) and inversely related to microbial biomass P with a scaling exponent of −0.234 (95% CI −0.289 to −0.179). Relative to CUE, biomass specific turnover time increased with a scaling exponent of 0.509 (95% CI 0.467–0.551). CUE increased weakly with mean annual temperature. CUE declined with increasing soil pH reaching a minimum at pH 7.0, then increased again as soil pH approached 9.0, a pattern consistent with pH trends in the ratio of fungal : bacteria abundance and growth. Structural equation models that related geographic variables to CUE component variables showed the strongest connections for paths linking latitude and pH to β‐glucosidase activity and soil C:N:P ratios. The integration of stoichiometric and metabolic models provides a quantitative description of the functional organization of soil microbial communities that can improve the representation of CUE in microbial process and ecosystem simulation models.

Evidence that summer jellyfish blooms impact Pacific Northwest salmon production

AbstractInterannual variability in salmon (Oncorhynchus spp.) production in the northeast Pacific is understood to be driven by oceanographic variability and bottom‐up processes affecting prey availability to juvenile salmon. Scyphozoan jellyfish have an important role in shaping the pathways of energy flow through pelagic food webs. While jellyfish obtain high production rates and biomasses as major consumers of zooplankton production, they have few predators and may divert plankton production away from higher trophic levels. Although jellyfish are planktivorous and juvenile coho (O. kisutch) and Chinook (O. tshawytscha) salmon are mainly piscivorous, they may be indirect competitors for plankton production. Ecosystem model simulations suggested that among all trophic interactions within the Pacific Northwest coastal food web, juvenile salmon are particularly sensitive to jellyfish blooms, and that salmon production will be suppressed in years of high summer jellyfish biomass. Pelagic surveys off Oregon and Washington (1999–2012) were used to examine the interannual relationship between salmon production and the dominant jellyfish species, the sea nettle Chrysaora fuscescens, off the Pacific Northwest coast. There was a significant, negative correlation between sea nettle biomass and the strength of adult coho and Chinook salmon returns to the Columbia River. Examination of spatial distributions across years showed a positive association between sea nettles and salmon. Within individual years, significant differences between the distribution of sea nettles and yearling coho and Chinook salmon generally occurred during cooler ocean summers, perhaps due to the greater expanse of optimal salmon habitat resulting from more upwelling. Whether the association is behavioral or a product of oceanographic processes, association enhances the opportunity for indirect competition. Examination of feeding incidence in September showed that salmon stomachs were less full at locations with higher sea nettle biomass.

Effects of intensive forest management on net climate impact of energy biomass utilisation from final felling of Norway spruce

The main objective of this work was to study the effects of intensive forest management on net climate impact of energy biomass (logging residues and/or stumps and coarse roots) utilisation from final felling of Norway spruce (Picea abies L. Karst) grown on medium-fertile site under boreal conditions in Finland. We employed forest ecosystem model simulations and a life cycle assessment (LCA) tool to calculate net CO2 exchange for utilising biomass in biosystem and coal in fossil system. In the biosystem, baseline management (business as usual, BT) and management with maintaining 30% higher stocking in thinning than in the BT regime were used. In addition, nitrogen fertilisation and improved planting material both alone and as combined were used to enhance growth in order to assess effects of intensive management on net climate impact. Carbon neutrality of biomass utilisation under alternative management was compared with the utilisation of coal. We found that the carbon neutrality of biomass utilisation varied between 0.5 and 3.4 (i.e. from partial to full neutrality), depending on the management applied. Under intensified management, CO2 emissions associated with energy biomass utilisation could be offset by forest ecosystem carbon sequestration over the following 20 years. Under the BT regime, such compensation could not be fully achieved over the rotation, but the utilisation of biomass produced less emissions per unit of energy than the use of coal. From a climate change mitigation point of view, the intensive management of Norway spruce could increase the climate benefits of energy biomass utilisation.

Litter dominates surface fluxes of carbonyl sulfide in a Californian oak woodland

AbstractCarbonyl sulfide (COS) is a promising tracer for partitioning terrestrial photosynthesis and respiration from net carbon fluxes, based on its daytime co‐uptake alongside CO2 through leaf stomata. Because ecosystem COS fluxes are the sum of plant and soil fluxes, using COS as a photosynthesis tracer requires accurate knowledge of soil COS fluxes. At an oak woodland in Southern California, we monitored below‐canopy surface (soil + litter) COS and CO2 fluxes for 40 days using chambers and laser spectroscopy. We also measured litter fluxes separately and used a depth‐resolved diffusion‐reaction model to quantify the role of litter uptake in surface COS fluxes. Soil and litter were primarily COS sinks, and mean surface COS uptake was small (∼1 pmol m−2 s−1). After rainfall, uptake rates were higher (6–8 pmol m−2 s−1), and litter contributed a significant fraction (up to 90%) to surface fluxes. We observed rapid concurrent increases in COS uptake and CO2 efflux following the onset of rain. The patterns were similar to the Birch effect widely documented for soils; however, both COS and CO2 flux increases originated mainly in the litter. The synchronous COS‐CO2 litter Birch effect indicates that it results from a rapid increase in litter microbial activity after rainfall. We expect that the drying‐rewetting cycles typical for mediterranean and other semiarid ecosystems create a pronounced seasonality in surface COS fluxes. Our results highlight that litter uptake is an important component of surface COS exchange that needs to be taken into account in ecosystem COS budgets and model simulations.

A simplified, data-constrained approach to estimate the permafrost carbon-climate feedback.

We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation–Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2–33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9–112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change (γ sensitivity) of −14 to −19 Pg C °C−1 on a 100 year time scale. For CH4 emissions, our approach assumes a fixed saturated area and that increases in CH4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10–18%. The simplified approach presented here neglects many important processes that may amplify or mitigate C release from permafrost soils, but serves as a data-constrained estimate on the forced, large-scale permafrost C response to warming.

Review of the current methods used to assess the values of coefficients, sensitivity, and adequacy of simulation models of aquatic ecosystems

The major principles, current methods, and approaches to solving optimization problems in assessing parameters for simulation models of aquatic ecosystems and their sensitivity to changes in the values of model parameters are considered. Analysis of the practical application of different methods to model calibration shows that no method of global optimization for complex hydrological models and models of aquatic ecosystems can guarantee obtaining a unique and best solution. Some results are shown, which have been obtained in solving the problem of the choice of parameters for the biohydrochemical block of a simulation model of Neva Bay (NB), the Gulf of Finland. The process of solving the optimization problem is formalized in the form of a two-stage direct-search algorithm: a random search algorithm (global search in the entire parameter space), followed by a local search by a modified Nelder-Mead simplex method.

Effects of climate change and management on net climate impacts of production and utilization of energy biomass in Norway spruce with stable age‐class distribution

AbstractWe studied the effects of climate change and forest management scenarios on net climate impacts (radiative forcing) of production and utilization of energy biomass, in a Norway spruce forest area over an 80‐year simulation period in Finnish boreal conditions. A stable age‐class distribution was used in model‐based analyses to identify purely the management effects under the current and changing climate (SRES B1 and A2 scenarios). The radiative forcing was calculated based on an integrated use of forest ecosystem model simulations and a life cycle assessment (LCA) tool. In this work, forest‐based energy was used to substitute coal, and current forest management (baseline management) was used as a reference management. In alternative management scenarios, the stocking was maintained 20% higher in thinning compared to the baseline management, and nitrogen fertilization was applied. Intensity of energy biomass harvest (e.g. logging residues, coarse roots and stumps) was varied in the final felling of the stands at the age of 80 years. Also, the economic profitability (NPV, 3% interest rate) of integrated production of timber and energy biomass was calculated for each management scenario. Our results showed that compared to the baseline management, climate benefits could be increased by maintaining higher stocking in thinning over rotation, using nitrogen fertilization and harvesting logging residues, stumps and coarse roots in the final felling. Under the gradually changing climate (in both SRES B1 and A2), the climate benefits were lower compared to the current climate. Trade‐offs between NPV and net climate impacts also existed.

Geographic variation in Pacific herring growth in response to regime shifts in the North Pacific Ocean

Pacific herring populations at eight North Pacific Rim locations were simulated to compare basin-wide geographic variations in age-specific growth due to environmental influences on marine productivity and population-specific responses to regime shifts. Temperature and zooplankton abundance from a three-dimensional lower-trophic ecosystem model (NEMURO: North Pacific Ecosystem Model for Understanding Regional Oceanography) simulation from 1948 to 2002 were used as inputs to a herring bioenergetics growth model. Herring populations from California, the west coast of Vancouver Island (WCVI), Prince William Sound (PWS), Togiak Alaska, the western Bering Sea (WBS), the Sea of Okhotsk (SO), Sakhalin, and Peter the Great Bay (PGB) were examined. The half-saturation coefficients of herring feeding were calibrated to climatological conditions at each of the eight locations to reproduce averaged size-at-age data. The depth of averaging used for water temperature and zooplankton, and the maximum consumption rate parameter, were made specific to each location. Using the calibrated half-saturation coefficients, the 1948–2002 period was then simulated using daily values of water temperature and zooplankton densities interpolated from monthly model output. To detect regime shifts in simulated temperatures, zooplankton and herring growth rates, we applied sequential t-test analyses on the 54years of hindcast simulation values. The detected shifts of herring age-5 growth showed closest match (69%) to the regime shift years (1957/58, 1970/71, 1976/77, 1988/89, 1998/99). We explored relationships among locations using cluster and principal component analyses. The first principal component of water temperature showed good correspondence to the Pacific Decadal Oscillation and all zooplankton groups showed a pan-Pacific decrease after the 1976/77 regime shift. However, the first principal component of herring growth rate showed decreased growth at the SO, PWS, WCVI and California locations and increased growth at the Sakhalin, WBS and Togiak locations after 1977. The SO location belonged to the same cluster as the location in with the eastern North Pacific. The calibrated half-saturation coefficients affected the degree to which growth was sensitive to interannual variation in water temperature versus zooplankton. For example, the half-saturation values for the SO location resulted in very efficient feeding that shifted the sensitivity of herring growth from food to temperature. The model results demonstrate how geographic specificity of bioenergetics parameters, coupled with location-specific variation in temperature and food, can combine to determine local and regional responses of fish growth to climate forcing.

Eco-hydrodynamic Modelling of Chini Lake: Model Description

In this study, we coupled a three-dimensional hydrodynamic model with an ecosystem model and applied it to the shallow complex floodplain wetland of Chini Lake in Malaysia. Our objective was to provide a better understanding of the lake’s ecosystem dynamics under different forcing mechanisms. Simulations and validation were performed over a dry month period. Wind speed ranged between 0 and 7.7 m s−1, whilst air temperature ranged between 22.0 and 35.6 °C. Advective transport driven by wind stress was the dominant physical force that shaped the water quality variations during the dry season. Convective circulation intermittently influenced the circulation during calm conditions. Nutrient concentration and stratification of dissolved oxygen (DO) varied between the lakes. Wind events saw patterns of the surface DO concentrations move spatially in the direction of the wind. The ecosystem model simulation suggested that the water quality in Chini Lake was influenced by macrophyte production, although the dissolved and particulate organic carbon accounted for the major fraction of organic matter content in the lake.

Dynamic Eco-industrial Model of Forest Rich Developing Nations: Application to the Bolivian Forestry Sector and National Economy

We combined ecosystem simulation modeling with emergy accounting to develop the National Eco-industrial Forestry System (NEIFS), a spatially aggregated model for exploring the role that renewable (forests) and nonrenewable (natural gas) resources could play in the development of an underdeveloped nation. NEIFS was applied to simulate the Bolivian national economy considering the forestry and natural gas sectors under four different scenarios and for the time period between 2005 and 2205. The four scenarios (business-as-usual; increased domestic use; increased export of natural resources; and improved national industrialization) were simulated to observe the behavior of soil/carbon storage, wood reserves, natural gas reserve, national assets, money supply (M4), and total national debt. Results showed that people of Bolivia would enjoy twice the standard of living if its forest products sector were industrialized and it used more of its forest and gas domestically. Thus, simply increasing the exports of natural resources will not increase the well-being of Bolivians. Only when Bolivia’s forest products industry was restructured so that it processed the raw wood into manufactured products, did the country’s citizens see an increase in their well-being. Promisingly, NEIFS showed that this increase in standard of living must not come at the expense of depleting the forests. More simulations should be conducted with NEIFS to determine which rate of gas depletion can maximize the long-term well-beingof the nation’s citizens.

Net climate impacts of forest biomass production and utilization in managed boreal forests

AbstractIn this work, we studied the potentials offered by managed boreal forests and forestry to mitigate the climate change using forest‐based materials and energy in substituting fossil‐based materials (concrete and plastic) and energy (coal and oil). For this purpose, we calculated the net climate impacts (radiative forcing) of forest biomass production and utilization in the managed Finnish boreal forests (60°–70°N) over a 90‐year period based on integrated use forest ecosystem model simulations (on carbon sequestration and biomass production of forests) and life‐cycle assessment (LCA) tool. When studying the effects of management on the radiative forcing in a system integrating the carbon sink/sources dynamics in both biosystem and technosystem, the current forest management (baseline management) was used a reference management. Our results showed that the use of forest‐based materials and energy in substituting fossil‐based materials and energy would provide an effective option for mitigating climate change. The negative climate impacts could be further decreased by maintaining forest stocking higher over the rotation compared to the baseline management and by harvesting stumps and coarse roots in addition to logging residues in the final felling. However, the climate impacts varied substantially over time depending on the prevailing forest structure and biomass assortment (timber, energy biomass) used in substitution.

Potential of forest biomass production and utilization for mitigation of climate change in boreal conditions

The aim of this work was to study the potential of forest biomass production and utilization for mitigating climate change in boreal conditions, based on integrated use of forest ecosystem model (SIMA) simulations and life cycle assessment (LCA). More specifically, it was studied how forest management (e.g. thinning regime, nitrogen fertilization, rotation length), harvesting intensity (timber, logging residues, stumps and coarse roots in the final felling) and gradually changing climate affect in Finnish conditions forest biomass production (timber and energy biomass) (Papers I, III, IV), carbon neutrality (Paper I) and net climate impacts of forest biomass production and utilization in substituting fossilintensive materials and fuels (Paper III, IV). Furthermore, it was studied the need to adapt the cultivation of the main Finnish tree species under the gradually changing climate (Paper II). This work showed that by modifying the business-as-usual (baseline) management and by increasing the harvesting intensity, we may increase simultaneously forest biomass production, carbon sequestration and stocks of forests, and climate benefits of forest biomass production and utilization. This could be done by maintaining higher stocking over a rotation (of 60 to 80 years) compared to the baseline management and using nitrogen fertilization, and harvesting in addition to timber, also logging residues, stumps and coarse roots for energy in the final felling. However, some trade-offs exist between the economic profitability of forest biomass production and climate impacts of forest biomass production and utilization. The impacts will also vary over time depending on the prevailing environmental conditions, forest structure and forest biomass assortments used in substitution. To conclude, gradual adaptation of forest management and utilization is needed in the future, taking into account the prevailing environmental conditions (climate, site) and uncertainties related to the climate change, to fully utilize the positive effects of climate change and reduce the negative ones.