Potential Primary Production Research Articles

气候变化和人类活动对中国陆地生态系统总初级生产力的影响厘定研究

总初级生产力（GPP）是生态系统植被光合作用生成有机物的能力表征，是生态系统服务功能的基础，关系到区域社会经济可持续发展及区域生态安全。基于生态系统过程模型CEVSA2，应用中分辨率成像光谱仪（MODIS）卫星遥感的叶面积指数数据产品（MCD15A2H），以强迫法构建了遥感数据驱动的模型新版本——CEVSA-RS；基于CEVSA-RS模拟分析了气候变化和人类活动对中国陆地生态系统GPP时空变化的相对影响，从气候潜在总初级生产力（GPP_CL）和现实总初级生产力（GPP_RS）的大小和趋势两方面厘定了人类活动影响。2000至2017年全国平均潜在GPP （1016.36 gC m^-2a^-1）略高于对应现实GPP （962.85 gC m^-2a^-1），但存在明显的空间分异：长江以南大部、秦岭、太行山脉以东以及大兴安岭以东和长白山地区等森林植被覆盖区，现实GPP高于潜在GPP；而西部草地及灌丛等地区现实GPP低于潜在GPP。全国GPP呈显著增加趋势（P<0.05），其中现实GPP的增速（46.04 gC m^-210a^-1）高于潜在GPP的增速（41.46 gC m^-210a^-1），人类活动影响促进GPP增长，主要体现在华南地区和华北平原等地；内蒙古东部、东北平原北部、青藏高原西部等地人类活动呈负面影响。人类活动影响大于气候影响的区域可达全国陆地面积的53%，其中西部生态相对脆弱的草地区人类活动仍为负面影响，这些地区以草定畜，发展草牧业和保护生态，仍然任重道远。;Gross primary productivity (GPP) is the fundament of all ecological services that ecosystems can provide, and its change will influence the sustainable development of regional socio-economic and ecological security. Based on the ecosystem process model CEVSA2, this study applied the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite remote sensing data to construct a new version of the remote sensing data-driven model, CEVSA-RS. The relative impacts of climate change and human activities on the spatial and temporal changes of terrestrial ecosystem gross primary productivity were analyzed based on CEVSA-RS, and the impacts of human activities were determined in terms of both the magnitude and trends of potential gross primary productivity (GPP_CL) driven by climate and actual gross primary productivity (GPP_RS) driven by climate and remote sensing. According to the national average, potential GPP (1016.36 gC m^-2a^-1) was slightly higher than actual GPP (962.85 gC m^-2a^-1) from 2000 to 2017. However, there is an obviously spatial disparity:the actual GPP is higher than the potential GPP in forested vegetation cover areas such as most of the south of the Yangtze River, the east of the Qinling and Taihang Mountains, and the east of the Daxinganling and Changbai Mountain areas. Meanwhile, the actual GPP is lower than the potential GPP in areas such as grassland and shrubland over western China. The GPP of whole Chinese terrestrial ecosystems showed a significant increasing trend (P<0.05), and the increasing speed of actual GPP (46.04 gC m^-210a^-1) exceeded that of potential GPP (41.46 gC m^-210a^-1), which meant human activities positively contributed to the most area in South China and North China Plain, while negatively impacted the ecosystems in eastern Inner Mongolia, northern Northeast Plains and western Tibetan Plateau. The areas where the impacts of human activities are greater than the impacts of climate chang accounted for 53% of the total land area in China. Considering negative impacts of human activities in the western China, as an area of fragile eco-environment, there is a long way to protect its ecosystems while to develop grassland-based husbandry through determining livestock stocking rate according forage production.

RESTREND-based assessment of factors affecting vegetation dynamics on the Mongolian Plateau

The landscape of the Mongolian Plateau (MP) is shaped by both climatic change and human activities. It is noteworthy to monitor regional vegetation dynamics and to discriminate the impacts of climatic and anthropogenic factors on vegetation productivity and diversity. To investigate human- and climate-driven changes in vegetation cover across the MP during 2000−2014, the residual trend analysis (RESTREND) method was applied to analyze the residuals of potential and actual net primary productivity (NPP) and further identify non-climatic effects on vegetation dynamics. Results suggested that the normalized difference vegetation index (NDVI) in growing seasons had been increasing at the rate of 0.002/a in the whole MP during 2000–2015. And potential NPP increased across 71% of the study area, revealed that climate change displayed a generally positive effect on vegetation recovery across the plateau; However, the 53% of the total study area exhibited an decreasing residuals trend, indicated that human activity played a negative role in vegetation recovery. Analysis of the combined effects of climate change and human activities indicated that vegetation recovered in 74% but degraded in 22% of area of the MP. Anthropogenic activity could thus be considered as the main influencing factor of vegetation degradation, while climate change was the main controlling factor of vegetation restoration. Besides, Climatic factors had a similar effect on vegetation dynamics in inner and outer Mongolia, but human activities showed a different pattern with a lesser (greater) effect on vegetation degradation (recovery) in inner Mongolia than in outer Mongolia, respectively.

Daily entropy of dissolved oxygen reveals different energetic regimes and drivers among high‐mountain stream types

AbstractHigh‐resolution time series of dissolved oxygen (DO) have revealed different ecosystem energetics regimes across various stream types. Ecosystem energetic regimes are relevant to better understand the transformation and retention of nutrients and carbon in stream ecosystems. However, the patterns and controls of stream energetics in high‐mountain landscapes remain largely unknown. Here we monitored percent DO saturation (every 10 min) over 2 years in a glacier‐fed, krenal (groundwater‐fed) and a nival (snowmelt‐fed) stream as they are typical for the high mountains. We used daily Shannon entropy to explore the temporal dynamics of stream water DO and to infer information on the ecosystem energetics and on the potential drivers. We found that discharge modulated the drivers of DO variations at daily and seasonal scales. Elevated bed movement along with high turbidity and very high gas exchange rates drove the daily DO patterns in the glacier‐fed stream during snow and ice melt, whereas light seemed to drive DO dynamics in the krenal and nival streams. We found a window of favorable conditions for potential gross primary production (GPP) during the onset of the snowmelt in the glacier‐fed stream, whereas potential GPP seemed to extend over longer periods in the krenal and nival streams. Our findings suggest how the energetic regimes of these high‐mountain streams may change in the future as their biological and physical drivers change owing to climate warming.

Washouts as a source of dissolved elements to the coastal ocean in southern Brazil and its hydrogeological characteristics

The coastal zone of Rio Grande do Sul state, Brazil, presents several surficial water bodies (washouts), which act as a drainage system of the coastal plain. Considering the entire extension of the coast, the number of washouts is very significant, thus, this study aims to assess in an unprecedented way the availability of nutrients, carbon and iron, dissolved in washout waters and its contribution in terms of concentration to the coastal ocean. Furthermore, due to groundwater in the beach region being one of the major sources for the formation and maintenance of these water bodies and influencing their hydrochemistry, we used the Ground Penetrating Radar as a tool to understand the interaction between the surficial and subterranean compartments, the influence of freshwater from the washouts on the aquifers and the extent of this interaction. The influence of the freshwater flux through the washout may reach 1000 m in length and a trough of up to 3.2 m. The medium outflow of freshwater by the washouts was heavily influenced by the rainfall, ranging between 0.12 m3 s−1 and 0.95 m3 s−1, in the dry and wet seasons, respectively. Throughout the Rio Grande do Sul coastal plain, washouts may represent 28% of the medium freshwater outflow from the Patos Lagoon Estuary and can top the outflow from Tramandaí Lagoon by 25%. The high outflow in the wet season impacted on the dissolved elements flux, with estimates of 274 ton y−1 for SiO44−, 0.42 ton y−1 for PO43−, 7.07 ton y−1 for total inorganic N, 1.7 ton y−1 for Fe and 262 ton y−1 for total dissolved C. Reckoning the values for the inorganic nitrogen flux, the washouts can support a potential primary production in the surf zone of 18 gC m−2 y−1, considering the entire Rio Grande do Sul coastal plain.

Effects of increased irradiance on biomass, photobiology, nutritional quality, and pigment composition of Arctic sea ice algae

Ice algae are key contributors to primary production and carbon fixation in the Arctic, and light availability is assumed to limit their growth and productivity. We investigated photo-physiological responses in sea ice algae to increased irradiance during a spring bloom in West Greenland. During a 14 d field experiment, light transmittance through sea ice was manipulated to provide 3 under-ice irradiance regimes: low (0.04), medium (0.08), and high (0.16) transmittances. Chlorophyll a decreased with elevated light availability relative to the control. Maximum dark-adapted photosynthetic efficiency (ΦPSII_max) showed an initially healthy and productive ice algae community (ΦPSII_max &gt; 0.6), with ΦPSII_max decreasing markedly under high-light treatments. This was accompanied by a decrease in the light utilization coefficient (α) and photosynthetic capacity (maximum relative electron transfer rate), and a decrease in the ratio of mono- to polyunsaturated fatty acids. This was partly explained by a corresponding increase of photoprotective pigments (diadinoxanthin and diatoxanthin), and a development of mycosporine-like amino acids as identified from a distinctive spectral absorption peak at 360 nm. After 14 d, in situ fluorescence imaging revealed significant differences in ΦPSII_max between treatments of dark-adapted cells (i.e. those sampled before sunrise and after sunset), during diel cycles, with clear chronic photoinhibition in high and medium treatments. Data demonstrate the high sensitivity of spring-blooming Arctic sea ice algae to elevated irradiance caused by loss of snow cover. The predicted loss of snow cover on landfast ice will negatively impact ice algae, their potential primary production, and nutritional quality for higher trophic levels.

Correction

Previous article FreeCorrectionLauri OksanenLauri OksanenDepartment of Arctic and Marine Biology, UiT–The Arctic University of Norway, Campus Alta, 9510 Alta, Norway; and Department of Biology, Section of Ecology, University of Turku, 20014 Turku, Finland Search for more articles by this author Original articleExploitation Ecosystems in Gradients of Primary ProductivityFull TextPDF Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreIn the 1981 article by Oksanen et al. titled “Exploitation Ecosystems in Gradients of Primary Productivity” (American Naturalist 118:240–261), figure 2 has a potentially confusing technical flaw that should have been fixed decades ago. Figure 2 was intended to consist of three panels, laid side by side, as in the corrected figure 2. However, doing the artwork by hand was so challenging that I had to draw each panel on a separate A4 sheet. In response, the technical editors decided to publish the panels as if they were separate figures, which did improve the visual clarity of figure 2. Unfortunately, however, the legend explaining the entire figure 2 now landed under figure 2a. Moreover, the word “systems” was edited to the singular, which made it hard for the reader to guess that the first sentence refers to the entire figure 2. Here, figure 2 is laid out as initially intended.Figure 2. Carnivore (C), herbivore (H), and plant (P) systems at different points of the productivity (G) axis. Unstable equilibrium is a solid dot; stable equilibrium is a dot with a star. a, An unproductive system where the plant isocline (the rightward-sloping surface) remains well below the carnivore isocline. The herbivore isocline (the surface bending backward from the plane of the page) crosses the plant isocline on the right side of its hump and in the C=0 plane, creating a stable herbivore-plant equilibrium. b, A system where the potential primary productivity has twice the value it had in figure 2a. The herbivore-plant equilibrium is unstable, so that sustained cyclic changes in plant and herbivore density are to be expected. c, Here the potential productivity is 1.25 times that of the system in figure 2b. A locally stable carnivore-herbivore-plant equilibrium has been established.View Large ImageDownload PowerPointMoreover, the article contains two confusing typos on page 255, in the first line of the last paragraph. The numbers of the figures referred to are incorrect. The line ought to be as follows: “A comparison between figure 3 and figure 5 suggests further observations.” Previous article DetailsFiguresReferencesCited by The American Naturalist Volume 195, Number 6June 2020 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/708807 Views: 180 HistorySubmitted February 11, 2020Published online April 06, 2020 © 2020 by The University of Chicago. All rights reserved. Crossref reports no articles citing this article.Related articlesExploitation Ecosystems in Gradients of Primary Productivity15 Oct 2015The American Naturalist

Monitoring and driving force analysis of net primary productivity in native grassland: A case study in Xilingol steppe, China

Grassland is an important type of terrestrial ecosystem. Using remote sensing technology to study the change and driving force of native grassland productivity at large scale is an important way to understand the ecological status of grassland. In this study, potential and actual net primary productivity (NPP) of Xilingol steppe from 2000 to 2018 were examined based on climatic model and light-use efficiency model, respectively. NPP damage value driven by human activities was calculated from the difference between potential and actual NPP. The least square method was used to analyze the temporal and spatial variation of NPP in Xilingol and the driving role of climate and human activities on NPP. The results showed that NPP in Xilingol increased from west to east, with mean annual NPP being 271.54 g C·m-2·a-1, the area with increased NPP (grassland restoration) being 36500 km2, and the area with decreased NPP (grassland degradation) being 59900 km2. The potential NPP tended to rise under the driving force of temperature and precipitation, with an average annual increase of 6.5 g C·m-2·a-1, which indicated that regional climate played a positive role in the improvement of NPP in Xilingol steppe, and that human activities were the main driving force for grassland degradation. The value of NPP damage driven by human activities decreased from east to west and from south to north, with the highest value in Wuzhumuqin meadow and southern steppe. Human activities, such as mining and reclamation, had the most obvious negative impact on grassland NPP.

Implications of different nitrogen input sources for potential production and carbon flux estimates in the coastal Gulf of Mexico (GOM) and Korean Peninsula coastal waters

Abstract. The coastal Gulf of Mexico (GOM) and coastal sea off the Korean Peninsula (CSK) both suffer from human-induced eutrophication. We used a nitrogen (N) mass balance model in two different regions with different nitrogen input sources to estimate organic carbon fluxes and predict future carbon fluxes under different model scenarios. The coastal GOM receives nitrogen predominantly from the Mississippi and Atchafalaya rivers and atmospheric nitrogen deposition is only a minor component in this region. In the CSK, groundwater and atmospheric nitrogen deposition are more important controlling factors. Our model includes the fluxes of nitrogen to the ocean from the atmosphere, groundwater and rivers, based on observational and literature data, and identifies three zones (brown, green and blue waters) in the coastal GOM and CSK with different productivity and carbon fluxes. Based on our model results, the potential primary production rate in the inner (brown water) zone are over 2 gC m−2 d−1 (GOM) and 1.5 gC m−2 d−1 (CSK). In the middle (green water) zone, potential production is from 0.1 to 2 (GOM) and 0.3 to 1.5 gC m−2 d−1 (CSK). In the offshore (blue water) zone, productivity is less than 0.1 (GOM) and 0.3 (CSK) gC m−2 d−1. Through our model scenario results, overall oxygen demand in the GOM will increase approximately 21 % if we fail to reduce riverine N input, likely increasing considerably the area affected by hypoxia. Comparing the results from the USA with those from the Korean Peninsula shows the importance of considering both riverine and atmospheric inputs of nitrogen. This has direct implications for investigating how changes in energy technologies can lead to changes in the production of various atmospheric contaminants that affect air quality, climate and the health of local populations.

Implications of Glacial Melt-Related Processes on the Potential Primary Production of a Microphytobenthic Community in Potter Cove (Antarctica)

The Antarctic Peninsula experiences a fast retreat of glaciers, which results in an increased release of particles and sedimentation and, thus, a decrease in the available photosynthetic active radiation (PAR, 400-700 nm) for benthic primary production. In this study, we investigated how changes in the general sedimentation and shading patterns affect the primary production by benthic microalgae, the microphytobenthos. In order to determine potential net primary production and respiration of the microphytobenthic community, sediment cores from locations exposed to different sedimentation rates and shading were exposed to PAR of 0-70 mu.mol photons m(-2)s(-1). Total oxygen exchange rates and microphytobenthic diatom community structure, density, and biomass were determined. Our study revealed that while the microphytobenthic diatom density and composition remained similar, the net primary production of the microphytobenthos decreased with increasing sedimentation and shading. By comparing our experimental results with in situ measured PAR intensities, we furthermore identified microphytobenthic primary production as an important carbon source within Potter Cove's benthic ecosystem. We propose that the microphytobenthic contribution to the total primary production may drop drastically due to Antarctic glacial retreat and related sedimentation and shading, with yet unknown consequences for the benthic heterotrophic community, its structure, and diversity.

Driving Mechanism of Gross Primary Production Changes and Implications for Grassland Management on the Tibetan Plateau

The contribution of climatic change and anthropogenic activities to vegetation productivity are not fully understood. In this study, we determined potential climate-driven gross primary production (GPPp) using a process-based terrestrial ecosystem model, and actual gross primary production (GPPa) using MODIS Approach in alpine grasslands on the Tibetan Plateau from 2000 to 2015. The GPPa was influenced by both climatic change and anthropogenic activities. Gross primary production caused by anthropogenic activities (GPPh) was calculated as the difference between GPPp and GPPa. Approximately 75.63% and 24.37% of the area percentages of GPPa showed increasing and decreasing trends, respectively. Climatic change and anthropogenic activities were dominant factors responsible for approximately 42.90% and 32.72% of the increasing area percentage of GPPa, respectively. In contrast, climatic change and anthropogenic activities were responsible for approximately 16.88% and 7.49% of the decreasing area percentages of GPPa, respectively. The absolute values of the change trends of GPPp and GPPh of meadows were greater than those of steppes. The GPPp change values were greater than those of GPPh at all elevations, whereas both GPPp and GPPh showed decreasing trends when elevations were greater than or equal to 5000 m, 4600 m and 4800 m in meadows, steppes and all grasslands, respectively. Climatic change had stronger effects on the GPPa changes when elevations were lower than 5000 m, 4600 m and 4800 m in meadows, steppes and all grasslands, respectively. In contrast, anthropogenic activities had stronger effects on the GPPa changes when elevations were greater than or equal to 5000 m, 4600 m and 4800 m in meadows, steppes and all grasslands, respectively. Therefore, the causes of actual gross primary production changes varied with elevations, regions and grassland types, and grassland classification management should be considered on the Tibetan Plateau.

Time‐varying responses of lake metabolism to light and temperature

AbstractLight is a primary driver of lake ecosystem metabolism, and the dependence of primary production on light is often quantified as a photosynthesis‐irradiance or “P‐I” curve. The parameters of the P‐I curve (e.g., the maximum primary production when light is in excess) can change through time due to a variety of biological factors (e.g., changes in biomass or community composition), which themselves are subject to external drivers (e.g., herbivory or nutrient availability). However, the relative contribution of variation in the P‐I curve to overall ecosystem metabolism is largely unknown. I developed a statistical model of ecosystem metabolism with time‐varying parameters governing the P‐I curve, while also accounting for the influence of temperature. I parameterized the model with dissolved oxygen time series spanning six summers from Lake Mývatn, a shallow eutrophic lake in northern Iceland with large temporal variability in ecosystem metabolism. All of the estimated parameters of the P‐I curve varied substantially through time. The sensitivity of primary production to light under light‐limiting conditions was particularly variable (&gt;15‐fold) and had a compensatory relationship with ambient light levels. However, the 3.5‐fold variation in the maximum potential primary production made the largest contribution to variation in ecosystem metabolism, accounting for around 90% of the variance in net ecosystem production. Much of the variation in maximum primary production was attributable to cyanobacterial blooms, which occur in some but not all years in Mývatn. Overall, these results illustrate how changes in the P‐I curve contribute substantially to temporal variation in lake ecosystem metabolism.

The age and species composition of mangrove forest directly influence the net primary productivity and carbon sequestration potential

Abstract Although mangroves inhabit only 0.7% of global coastal zone, but they have a significant contribution to the global carbon. Primary production by mangroves provides a substantial source of energy for aquatic food webs. Net primary productivity and carbon sequestration potential play a pivotal role in understanding the characteristics of the forest ecosystem. Therefore, in order to assess whether the age of mangrove forest and species composition has any influence on the net primary productivity and carbon sequestration potential; six plots of different age group (2, 7, 8, 12, 13 yrs and natural population), and mangrove species combinations were studied in Pichavaram mangrove forest, Tamil Nadu, India. Soil temperature, net canopy photosynthesis and forest functional index significantly varied between mangrove species and age. Regression analysis showed that the soil pH and bulk density positively influenced the carbon sequestration potential which was significant between age group. Higher age group (13yrs) and the natural site showed two-fold higher (21.52 ± 0.72 gC/m2/day) net canopy photosynthesis. Forest functional index, shoot Biomass, root Biomass, plant biomass, carbon biomass and CO2 equivalent showed significant variation with species or age having maximum value in natural plot. Net primary productivity was significant between mangrove species or age. However, carbon sequestration potential increased with the increase in age of plants. Maximum carbon sequestration potential was found in Xylocarpus mekongensis. The data obtained from the present study can be effectively used for drafting conservation and management policies for the fragile mangrove forest ecosystem.

Representing Nitrogen, Phosphorus, and Carbon Interactions in the E3SM Land Model: Development and Global Benchmarking

AbstractOver the past several decades, the land modeling community has recognized the importance of nutrient regulation on the global terrestrial carbon cycle. Implementations of nutrient limitation in land models are diverse, varying from applying simple empirical down‐regulation of potential gross primary productivity under nutrient deficit conditions to more mechanistic treatments. In this study, we introduce a new approach to model multinutrient (nitrogen [N] and phosphorus [P]) limitations in the Energy Exascale Earth System Model (E3SM) Land Model version 1 (ELMv1‐ECA). The development is grounded on (1) advances in representing multiple‐consumer, multiple‐nutrient competition; (2) a generic dynamic allocation scheme based on water, N, P, and light availability; (3) flexible plant CNP stoichiometry; (4) prognostic treatment of N and P constraints on several carbon cycle processes; and (5) global data sets of plant physiological traits. Through benchmarking the model against best knowledge of global plant and soil carbon pools and fluxes, we show that our implementation of nutrient constraints on the present‐day carbon cycle is robust at the global scale. Compared with predecessor versions, ELMv1‐ECA better predicts global‐scale gross primary productivity, ecosystem respiration, leaf area index, vegetation biomass, soil carbon stocks, evapotranspiration, N2O emissions, and NO3‐ leaching. Factorial experiments indicate that representing the phosphorus cycle improves modeled carbon fluxes, while considering dynamic allocation improves modeled carbon stock density. We also highlight the value of using the International Land Model Benchmarking (ILAMB) package to evaluate and document performance during model development.

Mapping the spatial and temporal variability of the upwelling systems of the Australian south-eastern coast using 14-year of MODIS data

Coastal upwelling is important for marine ecosystems and the economy, because of its elevated primary and secondary productivity and large potential for fish catch. This study developed a scale-independent and semi-automatic image processing technique to map the upwelling areas along the 4500 km south-eastern coast of Australia from 14-year monthly MODIS Sea Surface Temperature (SST) data. The results show that there is significant spatial variability in the mapped upwelling areas, month to month, season to season and year to year. There is also strong temporal (month to month, seasonal and inter-annual) variability of the upwelling characteristics in area of influence, SST anomaly, chlorophyll-a concentrations and upwelling speed. This study identifies two prominent upwelling systems, the NSW system along the coast of New South Wales and the WVIC/SA system along the coast of western Victoria and adjacent South Australia. The NSW coastal upwelling system occurs more or less continuously from austral spring to autumn. The WVIC/SA coastal upwelling system is a seasonal upwelling system occurring in the austral summer. The NSW coastal upwelling system has a stronger upwelling intensity than the WVIC/SA system, in terms of area of influence, SST anomaly, chlorophyll-a concentrations and upwelling speed. We believe that the NSW coastal upwelling system, especially the northern and central parts, is mainly driven by the East Australian Current (EAC) and its eddies; while, the WVIC/SA coastal upwelling is a typical wind-driven system. In addition, the results indicate that the El Nino Southern Oscillation (ENSO) events are likely to have a low-to-moderate impact on both the NSW and the WVIC/SA coastal upwelling systems. The El Nino (La Nina) events tend to strengthen (weaken) upwelling intensity.

Using data mining techniques to model primary productivity from international long-term ecological research (ILTER) agricultural experiments in Austria

Primary productivity is in the foundation of farming communities. Therefore, much effort is invested in understanding the factors that influence the primary productivity potential of different soils. The International Long-Term Ecological Research (ILTER) is a network that enables valuable comparisons of data in understanding environmental change. In this study, we investigate three ILTER cropland sites and one long-term field experiment (LTE) outside of the ILTER network. The focus is on the influence of different management practices (tillage, crop residue incorporation, and compost amendments) on primary productivity. Data mining analyses of the experimental data were carried out in order to investigate trends in the productivity data. We generated predictive models that identify the influential factors that govern primary productivity. The data mining models achieved very high predictive performance (r > 0.80) for each of the sites. Preceding crop and crop of the current year were crucial for primary productivity in the tillage LTE and compost LTE, respectively. For both crop residue incorporation LTEs, plant-available Mg affected productivity the most, followed by properties such as soil pH, SOM, and the crop residue management. The results obtained by data mining are in line with previous studies and enhance our knowledge about the driving forces of primary productivity in arable systems. Hence, the models are considered very suitable and reliable for predicting the primary productivity at these ILTER sites in the future. They may also encourage researcher-farmer-advisor-stakeholder interaction, and thus create enabling environment for cooperation for further research around these ILTER sites.

Primary emissions and secondary aerosol production potential from woodstoves for residential heating: Influence of the stove technology and combustion efficiency

To reduce the influence of biomass burning on air quality, consumers are encouraged to replace their old woodstove with new and cleaner appliances. While their primary emissions have been extensively investigated, the impact of atmospheric aging on these emissions, including secondary organic aerosol (SOA) formation, remains unknown. Here, using an atmospheric smog chamber, we aim at understanding the chemical nature and quantify the emission factors of the primary organic aerosols (POA) from three types of appliances for residential heating, and to assess the influence of aging thereon. Two, old and modern, logwood stoves and one pellet burner were operated under typical conditions. Emissions from an entire burning cycle (past the start-up operation) were injected, including the smoldering and flaming phases, resulting in highly variable emission factors. The stoves emitted a significant fraction of POA (up to 80%) and black carbon. After ageing, the total mass concentration of organic aerosol (OA) increased on average by a factor of 5. For the pellet stove, flaming conditions were maintained throughout the combustion. The aerosol was dominated by black carbon (over 90% of the primary emission) and amounted to the same quantity of primary aerosol emitted by the old logwood stove. However, after ageing, the OA mass was increased by a factor of 1.7 only, thus rendering OA emissions by the pellet stove almost negligible compared to the other two stoves tested. Therefore, the pellet stove was the most reliable and least polluting appliance out of the three stoves tested. The spectral signatures of the POA and aged emissions by a High Resolution – Time of Flight – Aerosol Mass Spectrometer (Electron Ionization (EI) at 70 eV) were also investigated. The m/z 44 (CO2+) and high molecular weight fragments (m/z 115 (C9H7+), 137 (C8H9O2+), 167 (C9H11O3+) and 181 (C9H9O4+, C14H13+)) correlate with the modified combustion efficiency (MCE) allowing us to discriminate further between emissions generated from smoldering vs flaming conditions.

Upscaling site‐scale ecohydraulic models to inform salmonid population‐level life cycle modeling and restoration actions – Lessons from the Columbia River Basin

AbstractWith high‐resolution topography and imagery in fluvial environments, the potential to quantify physical fish habitat at the reach scale has never been better. Increased availability of hydraulic, temperature and food availability data and models have given rise to a host of species and life stage specific ecohydraulic fish habitat models ranging from simple, empirical habitat suitability curve driven models, to fuzzy inference systems to fully mechanistic bioenergetic models. However, few examples exist where such information has been upscaled appropriately to evaluate entire fish populations. We present a framework for applying such ecohydraulic models from over 905 sites in 12 sub‐watersheds of the Columbia River Basin (USA), to assess status and trends in anadromous salmon populations. We automated the simulation of computational engines to drive the hydraulics, and subsequent ecohydraulic models using cloud computing for over 2075 visits from 2011 to 2015 at 905 sites. We also characterize each site's geomorphic reach type, habitat condition, geomorphic unit assemblage, primary production potential and thermal regime. We then independently produce drainage network‐scale models to estimate these same parameters from coarser, remotely sensed data available across entire populations within the Columbia River Basin. These variables give us a basis for imputation of reach‐scale capacity estimates across drainage networks. Combining capacity estimates with survival estimates from mark–recapture monitoring allows a more robust quantification of capacity for freshwater life stages (i.e. adult spawning, juvenile rearing) of the anadromous life cycle. We use these data to drive life cycle models of populations, which not only include the freshwater life stages but also the marine and migration life stages through the hydropower system. More fundamentally, we can begin to look at more realistic, spatially explicit, tributary habitat restoration scenarios to examine whether the enormous financial investment on such restoration actions can help recover these populations or prevent their extinction. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Biogeochemical cycling and phyto- and bacterioplankton communities in a large and shallow tropical lagoon (Términos Lagoon, Mexico) under 2009–2010 El Niño Modoki drought conditions

Abstract. The 2009–2010 period was marked by an episode of intense drought known as the El Niño Modoki event. Sampling of the Términos Lagoon (Mexico) was carried out in November 2009 in order to understand the influence of these particular environmental conditions on organic matter fluxes within the lagoon's pelagic ecosystem and, more specifically, on the relationship between phyto- and bacterioplankton communities. The measurements presented here concern biogeochemical parameters (nutrients, dissolved and particulate organic matter [POM], and dissolved polycyclic aromatic hydrocarbons [PAHs]), phytoplankton (biomass and photosynthesis), and bacteria (diversity and abundance, including PAH degradation bacteria and ectoenzymatic activities). During the studied period, the water column of the Términos Lagoon functioned globally as a sink and, more precisely, as a nitrogen assimilator. This was due to the high production of particulate and dissolved organic matter (DOM), even though exportation of autochthonous matter to the Gulf of Mexico was weak. We found that bottom-up control accounted for a large portion of the variability of phytoplankton productivity. Nitrogen and phosphorus stoichiometry mostly accounted for the heterogeneity in phytoplankton and free-living prokaryote distribution in the lagoon. In the eastern part, we found a clear decoupling between areas enriched in dissolved inorganic nitrogen near the Puerto Real coastal inlet and areas enriched in phosphate (PO4) near the Candelaria estuary. Such a decoupling limited the potential for primary production, resulting in an accumulation of dissolved organic carbon and nitrogen (DOC and DON, respectively) near the river mouths. In the western part of the lagoon, maximal phytoplankton development resulted from bacterial activity transforming particulate organic phosphorus (PP) and dissolved organic phosphorus (DOP) to available PO4 and the coupling between Palizada River inputs of nitrate (NO3) and PP. The Chumpan River contributed only marginally to PO4 inputs due to its very low contribution to overall river inputs. The highest dissolved total PAH concentrations were measured in the El Carmen Inlet, suggesting that the anthropogenic pollution of the zone is probably related to the oil-platform exploitation activities in the shallow waters of the southern of the Gulf of Mexico. We also found that a complex array of biogeochemical and phytoplanktonic parameters were the driving force behind the geographical distribution of bacterial community structure and activities. Finally, we showed that nutrients brought by the Palizada River supported an abundant bacterial community of PAH degraders, which are of significance in this important oil-production zone.

Assessing maximum depth distribution, vegetated area, and production of submerged macrophytes in shallow, turbid coastal lagoons of the southern Baltic Sea

Submerged macrophytes improve water quality in shallow coastal lagoons but eutrophication often resulted in a degradation of macrophytes. Management measures that protect and restore macrophyte stands require knowledge on what limits macrophyte distribution. Information on macrophyte production and distribution in the Darss-Zingst Bodden Chain (southern Baltic Sea) is lacking since an almost complete loss of submerged vegetation in the 1980s. Nutrient input was reduced in the 1990s and macrophytes seem to recover, although turbidity is high and light conditions are still poor. However, this recovery raised hope that returning macrophytes could stabilize sediments and improve water clarity. In this study, seasonal changes in photosynthesis–irradiance curves of selected macrophyte species were used to calculate potential primary production in different depths and turbidity situations. Bathymetry of the area is then used to assess depth distribution and vegetated area. Since the so-calculated depth limits correspond well with the actual depth distribution in the field, macrophyte depth distribution is concluded to be mostly determined by light conditions. Most macrophytes grow in very shallow areas up to 50 cm depth where also 70% of potential primary production takes place. Present light conditions do not support a further expansion of macrophyte distribution in the DZBC.

Simulation of the Contribution of Phosphorus-Containing Minerogenic Particles to Particulate Phosphorus Concentration in Cayuga Lake, New York

Phosphorus (P) associated with minerogenic particles delivered from watersheds can interfere with the common use of total P (TP) concentration as a trophic state metric in lacustrine systems, particularly proximate to tributary entries, because of its limited bioavailability. The concentration of unavailable minerogenic particulate P (PPm/u), where it is noteworthy, should be subtracted from TP in considering primary production potential and trophic state levels. A first mass balance model for PPm/u is developed and tested here for Cayuga Lake, New York. This is supported by a rare combination of detailed information for minerogenic particle level dynamics for the tributaries and lake, the bioavailability of tributary particulate P (PP), and previously tested hydrothermal/transport and minerogenic particle concentration submodels. The central roles of major runoff events and localized tributary loading at one end of the lake in driving patterns of PPm/u in time and space are well simulated, including (1) the higher PPm/u concentrations in a shallow area (“shelf”) adjoining the inputs, relative to pelagic waters, following runoff events, and (2) the positive dependence of the shelf increases on the magnitude of the event. The PPm/u component of P was largely responsible for the higher summer average TP on the shelf vs. pelagic waters and the exceedance of a TP water quality limit on the shelf. The effective simulation of PPm/u allows an appropriate adjustment of TP values to avoid overrepresentation of potential primary production levels.