Changes In Primary Production Research Articles

Machine learning-based prediction and assessment of recent dynamics of forest net primary productivity in Romania

While the analysis of spatio-temporal changes in the net primary productivity (NPP) of forests can provide critical information on carbon cycle and climate change, these ecological trends have remained unclear in many countries worldwide, including Romania. By using complex (satellite, forest and climate) data, many sophisticated (machine learning) algorithms and some widely applied (the Mann-Kendall test and Sen's slope estimator) statistical procedures, this study investigates, for the first time, recent forest NPP trends (1987–2018) that occurred in Romania, in relation to climate change that affected the country over the past decades. Following the modelling, mapping and assessment of NPP dynamics, results showed almost exclusively positive trends for this ecological parameter, which accounts for ∼99% of all forest NPP changes that occurred throughout the country, after 1987. Interestingly, almost three quarters (∼73%) of all NPP increasing trends are statistically significant, which indicates that Romania's forests have recently experienced a large-scale improvement in carbon fluxes and stocks. Investigations of eco-climatic relationships suggest that climate change has partially contributed to these surprising NPP dynamics observed in recent decades. All these findings can provide valuable information for forest management and for many stakeholders and policymakers who operate in the forestry and climate fields in Romania.

Light use efficiency models incorporating diffuse radiation impacts for simulating terrestrial ecosystem gross primary productivity: A global comparison

Estimating dynamic changes in gross primary productivity (GPP) of terrestrial ecosystems has always been challenging. Indeed, light use efficiency (LUE) models are extensively employed to capture GPP dynamics. Improved big-leaf LUE models by introducing a cloudiness scalar and two-leaf LUE models by dividing the canopy into shaded and sunlit leaves are two improved families for addressing the widely-recognized effects of diffuse radiation on terrestrial ecosystem GPP. However, the global performance in simulating GPP dynamics between such models has not been evaluated comprehensively. Here, we assess and compare the global performance of the ten LUE models considering diffuse radiation impacts (CFLUX, DIFFUSE, CI-LUE, CCW, Wang's Model, CI-EF, TL-LUE, TL-LUEn, DTEC, and RTL-LUE) at 102 flux sites in a standardized framework. Results indicate that LUE models considering diffuse radiation impacts can explain 46.7–63.6% of daily GPP variability obtained by the eddy covariance technique. Seven of the ten models show a better performance across all ecosystems than MOD17, despite the relatively poor performance of three (i.e., DIFFUSE, Wang's Model, and DTEC). The seven improved models exhibiting a similar explanation of GPPEC perform poorly in evergreen broadleaf forests and croplands but well in deciduous broadleaf forests. Although two-leaf models with higher leaf area index (LAI) sensitivity and better model structure have greater potential to describe diffuse radiation fertilization (DRF), their performance in capturing GPP dynamics is limited by the uncertainties of remote sensing data. This study indicates the importance of accurate LAI for two-leaf models and emphasizes the necessity of incorporating diffuse radiation impacts into the global GPP estimates in the future.

Life Histories Vary with Primary Productivity in the Northern Gulf of Mexico

Human activities have increased nutrient delivery to aquatic ecosystems around the world, spurring primary productivity, and leading to the establishment and expansion of oxygen-limited “dead zones.” How will marine animals respond to these changing conditions? To address that question, we take a space-for-time approach and compare the traits of different marine invertebrates along a primary productivity gradient in the northern Gulf of Mexico. Previous studies have found that life history traits can be sensitive to prevailing environmental conditions. Using Holocene death assemblages collected from -20 meters offshore Alabama and Florida, we test the hypothesis that bivalve egg size, and bryozoan reproductive mode, vary with primary productivity. Based on previous studies, we expect populations in areas with an abundance of food to exhibit the following characteristics: 1) cupuladriid bryozoans will exhibit greater frequencies of clonal to aclonal reproduction; and 2) bivalves will produce smaller eggs due to greater juvenile survivorship and fecundity selection. We found that Discoporella depressa colonies show low frequencies of clonal reproduction overall, but that percent clonality was greater in coastal Alabama than Florida. Cupuladria colonies showed higher proportions of clonal reproduction, whereas Reussirella doma colonies exhibited exclusively aclonal reproduction. Egg size is positively correlated with the earliest stage of larval shell growth (PI size) in marine bivalves. Nucula proxima larval shell size varied inversely with primary productivity; larval shells were larger in Florida than Alabama. Preliminary live-dead results in both regions show limited evidence of change over time, in contrast with previous analyses of other bivalve species in the region. These space-for-time case studies highlight ways in which benthic marine invertebrates may respond to future anthropogenic driven changes in primary production in the coastal ocean.

Elodea mediates juvenile salmon growth by altering physical structure in freshwater habitats

Invasive species introductions in high latitudes are accelerating and elevating the need to address questions of their effects on Subarctic and Arctic ecosystems. As a driver of ecosystem function, submerged aquatic vegetation is one of the most deleterious biological invasions to aquatic food webs. The aquatic plant Elodea spp. has potential to be a widespread invader to Arctic and Subarctic ecosystems and is already established in 19 waterbodies in Alaska, USA. Elodea spp. has been found to alter ecosystem processes through multiple pathways; yet little is known about the impact of Elodea spp. on fish life history. A primary concern is the effect of Elodea spp. on juvenile Pacific salmon (Oncorhynchus spp.), because this invading plant can form dense stands in littoral zones, potentially impacting important freshwater rearing habitats used by juvenile fish for foraging and refuge from predators. We used a field experiment to test the effect of Elodea spp. on juvenile coho salmon (O. kisutch) growth in an infested lake near Cordova, Alaska, USA. We found that Elodea spp. stands result in reduced growth and a lower trophic position for juvenile coho salmon over the summer compared to habitats dominated by a native assemblage of aquatic plants. While infested sites were not associated with significant changes in water condition or primary productivity compared to sites dominated by native vegetation, zooplankton densities were reduced, and Elodea spp. height and vegetation richness increased macroinvertebrate densities. Combined, these results indicate that Elodea spp. may alter the flow of energy to juvenile salmon by restructuring space and affecting prey resources for rearing fish. Furthermore, these results suggest that widespread establishment of Elodea spp. may alter the quality of habitat for juvenile salmon and, by affecting juvenile fish growth, could lead to population-level impacts on salmon returns.

Landscape Transformation and Variation in Invasive Species Abundance Drive Change in Primary Production of Aquatic Vegetation in the Sacramento–San Joaquin Delta

Conversion of wetlands in the Sacramento–San Joaquin Delta beginning in the mid-1800s resulted in a pronounced shift from a wetland-dominated food web to one driven by open-water primary producers. Submersed and floating aquatic vegetation (SAV and FAV) now rank highest in potential net primary production (NPP) among producer groups, and provide a comparable amount of carbon to the detrital food web as marshes. However, important details of this contribution that relate to shifts in species composition and habitat extent were not understood. Here, we review how changes in aquatic vegetation influence NPP and trophic support from the historical to modern periods, within the modern period (the last 2 decades), and under future management and climate scenarios. We estimate that NPP of SAV and FAV during the historical period was approximately half that of today, before increases in open water and introduction of the highly productive water primrose. During the modern period (the last 20 years), high interannual variability in the extent and relative composition of aquatic vegetation species has driven significant variation in total NPP. This recent temporal variation is 6 to 13 times larger than projected changes in production from the potential future scenarios we modeled, including a reduction in FAV by 20% through control measures, substantial wetland restoration (and thus increased channel area that could support SAV and FAV), and increased salinity intrusion in the western Delta with climate warming, which favors native species with greater salinity tolerance. Large temporal swings in NPP of SAV and FAV cascade to influence the degree of carbon that flows to consumers through detrital pathways and herbivory. This volatility and interannual inconsistency in aquatic vegetation support of food webs make achieving wetland restoration goals for the Delta—which could lead to recovery of a portion of the NPP lost since historical times—even more imperative.

Assessing vulnerability of reptile hotspots through temporal trends of global change factors in the Iberian Peninsula

Habitat degradation and climate change are major threats to the long-term persistence of reptile populations. However, their roles on primary productivity instability remain unclear at certain scales. Besides, the design of protected areas has often overlooked reptiles or assumed that their ecological requirements are represented under the umbrella of more charismatic species. Here, we assess the vulnerability of areas of high diversity of reptiles in the Iberian Peninsula to global change using data from satellite imagery. We focused on primary productivity, climate and land-use change because they are indicators of environmental variability that might impair ecosystem functioning and alter wildlife communities. We used linear regressions to detect monotonic temporal trends in primary productivity (through the enhanced vegetation index, EVI) and climate (mean temperature and accumulated precipitation) at two spatial resolutions (10-km2 UTM squares and CORINE land-cover polygon level) over the period 2000–2020. We also determined how the strength of land-use and climate change affected the intensity of change in primary productivity at both spatial scales with multivariate linear regressions. We identified 339 hotspots (10-km2 UTM squares) and monotonic increments of temperature, EVI or both occurred in 43 %, 16 % and 22 % of them, respectively. Positive trends of the EVI were related to increasing temperatures and changes in shrubland and forest cover. Within the hotspots with monotonic increments in EVI and temperature, EVI increments occurred in 65 % of the CORINE polygons that did not change their land-cover type, with stronger increases in tree crops. Finally, the Natura 2000 network provides only moderate protection to reptile hotspots, being most of the vegetation types relatively underrepresented. The proportion of forest and shrubland protected by the Natura 2000 network was higher in hotspots where EVI changed. Our procedures are relevant to prioritize hotspots requiring ground monitoring that allows economic and time savings.

Complex pattern of environmental changes and organic matter preservation in the NE Ordos lacustrine depositional system (China) during the T-OAE (Early Jurassic)

The lower Toarcian black shale and mudstone succession of the Anya section in the northeastern Ordos Basin records a climatically controlled evolution of the lacustrine system during the negative carbon isotope excursion (NCIE) of the Toarcian oceanic anoxic event (T-OAE; ca. 183 Ma). In the Anya section, petrography integrated with climate proxies (Sr/Cu and Rb/Sr) and weathering indices (weathering index of Parker, chemical index of weathering and plagioclase index of alteration), suggests that a warm-humid climate with sporadic semihumid-semiarid intervals developed during the early Toarcian and was coincident with strong chemical weathering. Sr/Ba and S/TOC ratios suggest that the Anya section's rocks were generally deposited in freshwater. Four phases (phases A, B, C and D) in lake evolution are distinguished from the variation in petrographical and geochemical proxies providing clues about the drivers of environmental change and organic matter accumulation in the lacustrine basin. Phases A and C have a high preservation of organic matter derived from lake plankton (Type II-III kerogens), were characterized by anoxia, and coincided with high primary productivity. On the contrary, phases B and D indicate a low primary productivity and suboxic-oxic conditions, with a lower organic matter content of predominantly higher land plant origin (Type III kerogen). The accumulation of organic matter was mainly controlled by changes in primary productivity and redox conditions that were tightly linked to the local sedimentary evolution of the Ordos Basin and to global and regional climate. During the early Toarcian NCIE, the accumulation of organic-poor sediment and terrestrial organic matter may have been driven by enhanced seasonality, superimposing on local lake level changes. As a consequence, the peak of the T-OAE carbon cycle perturbation does not coincide with lacustrine black shale deposition and/or peak anoxia in this continental depositional system. This emphasizes the significance of local or regional environmental change on the carbon sequestration within lacustrine systems.

Biomarker evidence of the water mass structure and primary productivity changes in the Chukchi Sea over the past 70 years

The Chukchi Sea has experienced significant changes under global warming in the Common Era, including the shift of primary productivity. However, modern observations are too short to fully investigate the effects of environmental changes in this area. Here, we analyzed lipid biomarkers (e.g. long-chain n-alkanes, n-alkanols, n-alkanoic acids, diols, and sterols) from a sediment core (R07) collected from the Chukchi Sea shelf to determine phytoplankton primary productivity variations and factors influencing these changes over the past 70 years. Similar trends of the abundance of terrestrial ecosystem-derived compounds (e.g. long-chain n-alkanes, n-alkanols, n-alkanoic acids, and C32 1,15-diol) indicate that terrigenous input increased from ca. 1946 towards ca. 1983 and then decreased thereafter. In comparison, biomarkers with marine origin indicate that the ratio of diatoms to dinoflagellates increased after ca. 1983 towards the core-top (ca. 2011). Concurrent changes in terrigenous input and phytoplankton community indicated a shift in water mass structure at ca. 1983 (i.e. the Alaska Coastal Water decreased and the Bering Sea Water increased), which may be attributed to the phase shift of the Arctic Oscillation and/or unsynchronized flow changes in different water masses. Owing to the different water mass properties, the change of water mass structure caused intense water mixing and the resulting high turbidity in the study area, which led to light limitation for phytoplankton growth. These conditions probably account for the reduced phytoplankton primary productivity from ca. 1983 to ca. 2000 in the general trend of increasing. The results indicate that, in addition to global warming and sea ice retreat, other factors, such as change in regional water mass structure (i.e. different water masses), may also have a significant influence on the primary productivity and the phytoplankton community in the Chukchi Sea shelf.

Trends in Changes in Primary Phytoplankton Production According to Remote Sensing Data in the Deep-Sea Region of the Black Sea for 1998–2015

The analysis of long-term seasonal changes in the concentration of chlorophyll, the maximum rate of phytoplankton photosynthesis and water temperature in the surface layer of the open waters Black Sea from 1998 to 2015 has been carried out. The trends of these indicators were assessed. For the research, we used the data of satellite observations SeaWiFS and MODIS-Aqua, MODIS-Terra. Typical positive temperature trends of 4 % in the deep-water western part of the sea. An annual temperature rise in deep-water areas was noted in the western cyclonic circulation by 0.038 °C. According to average annual data in other areas, no increase was found. The increase was mainly due to the winter season. Negative trends of primary phytoplankton production within 16.4–18.6 % of the initial level according to average annual values throughout the deep-water area. Significance level — p < 0.1. A decrease in primary production was observed in the summer. There were no statistically significant directional changes in chlorophyll concentration based on averaged data over 18 years. In different parts of the deep-sea area, the direction of interannual and seasonal changes in all indicators was similar. The emerging trend towards a decrease in phytoplankton productivity in recent years may lead to a restructuring of the phytoplankton community.

Restored vegetation is more resistant to extreme drought events than natural vegetation in Southwest China

Large scale Ecosystem restoration projects (ERPs) have been implemented to restore vegetation and increase carbon stocks across China. However, whether restored vegetation is strongly resistant to Extreme drought events (EDEs) remains unclear, especially when compared to natural vegetation. Therefore, we used the standardized anomaly of 3-month Standard Precipitation-Evapotranspiration Index (SPEI) to characterize the spatial-temporal trends of EDEs, and figured out the capacity of restored vegetation to withstand the strongest EDE in Southwest China by analyzing their changes of Gross Primary Productivity (GPP) and Water Use Efficiency (WUE). The results showed that Southwest China had experienced six typical EDEs with increasing frequency and severity from 1982 to 2017, particularly the EDE during 2009–2010 (EDE 2009/2010) which had the longest duration and strongest severity. Overall, the EDE 2009/2010 substantially suppressed the vegetation GPP and ecosystem WUE in both restored and natural vegetation area. Compared with natural vegetation, the GPP and WUE of restored vegetation was relative higher and moreover, their GPP decreased more slowly during the EDE 2009/2010 and increased more quickly during the recovery period. This indicates that restored vegetation had a higher drought resistance to the EDE than natural vegetation. Additionally, karst landforms have a stronger negative impact on vegetation GPP and WUE during the EDE. Furthermore, the reduction in the afforestation areas was more obviously observed than that in natural forest areas. Therefore, we suggest that vegetation suitable for regional characteristics should be selected during vegetation restoration, such as afforestation in the non-karst areas.

Patterns of net primary production changes in eurasian steppes

The aim of the study. The aim of the study was to analyze changes in the above-ground (ANP), below-ground (BNP) and total net primary production (NPP), expressed in dry matter, in meadow, true and dry steppes along the latitudinal (from 56o to 43o N) and longitudinal (from 36o to 116o E) gradients. Methodology. Production characteristics of 32 steppes (9 meadow, 14 true and 9 dry steppes), obtained by the same method of minimal estimate, were analyzed. Main results. The ANP value in meadow steppes decreases from 10,2 to 3,1 t/ha per year, in true steppes from 6,7 to 0,7 t/ha per year and in dry steppes from 3,7 to 0,6 t/ha per year. The value of BNP in meadow steppes varies from 26,8 to 10,1 t/ha per year; in true steppes - from 25.7 to 7.7 t/ha per year; and in dry steppes - from 24,8 to 4,9 t/ha per year. The BNP changes from West to East were found not to follow the ANP changes: a decrease in ANP may be accompanied by an increase in BNP. According to the ANP estimates the analyzed steppes can be grouped as following: 1) ANP from 10 to 5; 2) ANP from 5 to 3; 3) ANP from 3 to 1; 4) ANP less than 1 t/ha per year. The first group is located between 56o and 51o NL and includes six meadow steppes and one true steppe. The second group includes all three types of steppes (three meadow, six true and one dry steppe) between 56o and 50o N. The third group of steppes, between 54° and 43° NL, consists of six true and seven dry steppes. At 50°N one true and one dry steppes are located with the smallest ANP. The first and the second groups are located in the same territory (from 56o to 50o N) and include both meadow and true steppes. About 70% of the meadow and half of the true steppes are characterized by the ANP ranging from 6.7 to 3.1 t/ha per year. In the northern part of the explored zone there are highly productive meadow steppes, whereas in its southern part there are true steppes with both high and low production. The third group of steppes, with production from 3 to 1 t/ha per year, includes seven low-productive true and eight dry steppes. The average ANP of true and dry steppes of this group are similar (2,2 t/ha per year). Consequently, the area from 54° to 43°N can be considered as a zone of dry steppes. Conclusion. There are no separate zones of meadow and real steppes, but there is a steppe zone that includes meadow and true steppes. The proposed division of the steppes and their zoning is made on the basis of ANP, which is the most important characteristic of any ecosystem.

DOT-1.1 (DOT1L) deficiency in C. elegans leads to small RNA-dependent gene activation

Methylation of histone H3 at lysine 79 (H3K79) is conserved from yeast to humans and is accomplished by Dot1 (disruptor of telomeric silencing-1) methyltransferases. The C. elegans enzyme DOT-1.1 and its interacting partners are similar to the mammalian DOT1L (Dot1-like) complex. The C. elegans DOT-1.1 complex has been functionally connected to RNA interference. Specifically, we have previously shown that embryonic and larval lethality of dot-1.1 mutant worms deficient in H3K79 methylation was suppressed by mutations in the RNAi pathway genes responsible for generation (rde-4) and function (rde-1) of primary small interfering RNAs (siRNAs). This suggests that dot-1.1 mutant lethality is dependent on the enhanced production of some siRNAs. We have also found that this lethality is suppressed by a loss-of-function of CED-3, a conserved apoptotic protease. Here, we describe a comparison of gene expression and primary siRNA production changes between control and dot-1.1 deletion mutant embryos. We found that elevated antisense siRNA production occurred more often at upregulated than downregulated genes. Importantly, gene expression changes were dependent on RDE-4 in both instances. Moreover, the upregulated group, which is potentially activated by ectopic siRNAs, was enriched in protease-coding genes. Our findings are consistent with a model where in the absence of H3K79 methylation there is a small RNA-dependent activation of protease genes, which leads to embryonic and larval lethality. DOT1 enzymes’ conservation suggests that the interplay between H3K79 methylation and small RNA pathways may exist in higher organisms.

Nutrient uptake plasticity in phytoplankton sustains future ocean net primary production.

Annually, marine phytoplankton convert approximately 50 billion tons of dissolved inorganic carbon to particulate and dissolved organic carbon, a portion of which is exported to depth via the biological carbon pump. Despite its important roles in regulating atmospheric carbon dioxide via carbon sequestration and in sustaining marine ecosystems, model-projected future changes in marine net primary production are highly uncertain even in the sign of the change. Here, using an Earth system model, we show that frugal utilization of phosphorus by phytoplankton under phosphate-stressed conditions can overcompensate the previously projected 21st century declines due to ocean warming and enhanced stratification. Our results, which are supported by observations from the Hawaii Ocean Time-series program, suggest that nutrient uptake plasticity in the subtropical ocean plays a key role in sustaining phytoplankton productivity and carbon export production in a warmer world.

Trees out‐forage understorey shrubs for nitrogen patches in a subarctic mountain birch forest

Nitrogen (N), acquired by roots and mycorrhizal fungi and supplied to plant foliage, is a growth‐limiting nutrient at the subarctic treeline. Due to this limitation, interspecific competition and acquisition of N is an important control on plant community composition and distribution. The ability of trees and shrubs to access N shapes community dynamics at this ecotone undergoing species range shifts and changes in primary productivity driven by climate change. Using 15N soil labelling we investigate the fate of soil inorganic N, and spatial distances over which trees and understorey shrubs access soil N, in a treeline forest. 15N was injected into soil rooting zones in discrete 1 m2 patches and foliar samples were collected from trees between 1 and 50 m away, and understorey shrubs between 0.5 and 11 m away from labelled soil. The 15N label was found in mountain birch trees up to 5 m, and in understorey shrubs up to 2 m, away from labelled soil. We estimate that 1.27% of pulse‐derived N was found in foliage of birch trees, compared to 1.16% in the understorey. However, mountain birch trees contributed only 31% of ecosystem leaf area index (LAI), thus there was a disproportionate allocation of added label to the birch canopy compared with its contribution to ecosystem LAI. The difference in root and mycorrhizal exploration distances and community N partitioning between mountain birch trees and understorey shrubs may confer competitive advantage to trees with respect to nitrogen and nutrient patches, which may alter plant community structures within these forests. This is particularly important considering predicted climate‐driven tree and tall shrub expansion in subarctic regions, with likely consequences for ecosystem N and carbon (C) cycling, as well as for community composition and biodiversity.

Net primary productivity changes associated with landslides induced by the 2008 Wenchuan Earthquake

AbstractThe 2008 Wenchuan Earthquake triggered massive landslide erosion, especially in mountainous terrain, which had a great impact on carbon storage of the local terrestrial ecosystem. However, variation in carbon flux and restoration of ecosystem function after the Wenchuan Earthquake remain open issues. In this study, we evaluated the current restored vegetation productive capability on the coseismic landslide scars through moderate resolution imaging spectroradiometer (MODIS) net primary productivity (NPP) imagery, and explored their sensitivity to meteorological, topographical, and geological factors. The spatio‐temporal evolution and future sustainability of NPP of the landslides after the Earthquake were revealed. The following results were obtained: (i) After 13 years, only 45.36% of the vegetation productivity capability of the landslide scars reached the pre‐earthquake level. (ii) Meteorological factors (precipitation and temperature) have strongest influences on vegetation productivity capability recovery over the coseismic landslide scars, followed by topography (aspect, slope, and altitude) and the lithology of landslides. (iii) The extremely significant improvement (p < 0.01) and significant improvement (0.01 ≤ p < 0.05) in annual NPP pixel values from 2008 to 2021 accounted for 18.92% and 28.30% of the total area, respectively. The slight degradation (p < 0.1) in annual NPP pixel values from 2008 to 2021 account for 0.01% of the total area. In general, the NPP has shown an improving trend since the Wenchuan Earthquake. Moreover, 60.95% of the total area shows the trends of continuous improvement in the future. This study provides important insight into how mega‐earthquakes affect regional ecosystem carbon flux and contributes to our understanding of ecosystem carbon cycles along with earthquake‐induced geohazard chains.

Size matters: Physiological sensitivity of the scallop Argopecten purpuratus to seasonal cooling and deoxygenation upwelling-driven events

Environment imposes physiological constraints which are life-stage specific as growth-maintenance and/or growth-reproduction energetic requirements are size and volume-dependent. The scallop Argopecten purpuratus, one of the most important bivalve species subjected to fishery and aquaculture along the Humboldt Current System, inhabits spaces affected by continuous changes in temperature, pH, oxygen, and food availability driven by remote and local oceanographic processes. Specifically, in Chile, this species is mainly cultured in central-north Chile where is permanently affected by upwelling events of dissimilar intensity and duration which generate local conditions of acidification, deoxygenation, and cooling with different magnitudes. However, to date, it remains unknown how this economic valuable resource is physiologically affected throughout its life cycle by the continuous environmental changes driven by upwelling events of different intensities and duration along the year. Here, for the first time, A. purpuratus life-stage physiological sensitivity was assessed at a seasonal scale through a year-field experiment where growth, calcification, and survivorship were evaluated. Our study shows how seasonal differences in the upwelling phenology (here measured as changes in temperature, dissolved oxygen, pH, and primary productivity, but also as the number, duration, and intensity of cooling and de-oxygenation events) notably impacted the A. purpuratus physiological performance from juvenile to adult life-stages. This was especially noticeable during the spring season which showed the most intense cooling and deoxygenation events driven by stronger favorable-upwelling winds and the lowest growth and gross calcification rates (the highest decalcification rates) where adult stages showed the lowest performance. On the other hand, A. purpuratus survivorship was not significantly affected by upwelling intensity which would be providing evidence of the high physiological flexibility and well-locally adapted is this species to fluctuating and occasional stressful environmental conditions. Our results are significantly relevant in the climate change context as some upwelling systems are at risk to change shortly (i.e., an upwelling intensification in frequency and intensity) as a consequence of changes in the atmospheric pressures that modulate favourable-upwelling winds. These changes may certainly increase the climate related-risks of the entire socio-ecological systems related to the fishery and aquaculture of A. purpuratus along the Humboldt Current System.

Net primary productivity exhibits a stronger climatic response in planted versus natural forests

Compared to planted forest ecosystems (PFE), natural forest ecosystems (NFE) generally have a longer history and theoretically have stronger environmental adaptability. Changes in net primary productivity (NPP) due to global change have been studied for many forest types, yet the underlying mechanism remain poorly understood. Using 926 forest plots (including both PFE and NFE) established between 2005 and 2020 in China, we found that NPP exhibited stronger climate and soil nutrient responses, with greater environmental plasticity, in PFE versus NFE. Several functional traits (e.g., leaf area, leaf nitrogen and phosphorus content) differed between NFE and PFE, but only weakly predicted spatial variation in NPP, as compared to the environmental factors. Overall, NPP in both NFE and PFE showed consistent responses to climate and soil nutrient changes. These environmental responses were weaker in coniferousforests than broadleaved forests. Direct effects of climatic factors on NPP were stronger than indirect effects. Overall, the effects of functional traits on NPP were mediated by climatic and edaphic factors. These findings provide guidance for more reliable predictions of NPP and succession in NFE and PFE in the context of global warming.

Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale.

Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two-three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries.

Southern westerly winds and paleoceanography of the San Jorge Gulf (SW-Atlantic ocean, Argentina) during the last 14,000 years

We use pollen and dinocyst assemblages from three sedimentary sequences of the San Jorge Gulf (SJG) to document the vegetation history of the extra-Andean/eastern Patagonia (Argentina), and the latitudinal variations of the Southern Westerly Wind Belt (SWWB) in relation with ocean changes during the Late Pleistocene and Holocene. Our results suggest that prior to 14 cal ka BP, the vegetation of the SJG was dominated by halophytic taxa probably related to arid conditions in coastal environments. After 14 cal ka BP, pollen data suggest the development of shrub and herb vegetation in the Patagonian steppe then characterized by semi-arid conditions. The 14 cal ka BP transition is marked by increasing Nothofagus pollen abundances, suggesting strong westerlies at the onset of the Antarctic Cold Reversal (ACR). This transition is also marked by the occurrence of marine palynomorphs (dinocysts, organic linings of foraminifers), which relate to sea-level rise. The dinocyst assemblages allowed us to quantitatively estimates changes in summer sea-surface temperature (SST) and annual net primary productivity. Between 14 and 10.8 cal ka BP, which encompasses the glacial termination and the early Holocene, dinocyst assemblages are dominated by Operculodinium centrocarpum (∼82%) and Spiniferites mirabilis (∼8%) that suggest warmer conditions than at present. The transition from early to middle Holocene was marked by high SWWB intensity as suggested by pollen assemblages, and an increase of heterotrophic taxa such as Brigantedinium spp., Echinidinium sp., Dubridinium sp., and the cysts of Polykrikos kofoidii, suggesting increased primary productivity and gradual cooling of surface water. After 4 cal ka BP, pollen data suggest a decrease in the SWWB intensity that correlates with glacier advances in Patagonia and a further decrease in summer SST in the SJG.

Offshore wind farms are projected to impact primary production and bottom water deoxygenation in the North Sea

The wind wake effect of offshore wind farms affects the hydrodynamical conditions in the ocean, which has been hypothesized to impact marine primary production. So far only little is known about the ecosystem response to wind wakes under the premisses of large offshore wind farm clusters. Here we show, via numerical modeling, that the associated wind wakes in the North Sea provoke large-scale changes in annual primary production with local changes of up to ±10% not only at the offshore wind farm clusters, but also distributed over a wider region. The model also projects an increase in sediment carbon in deeper areas of the southern North Sea due to reduced current velocities, and decreased dissolved oxygen inside an area with already low oxygen concentration. Our results provide evidence that the ongoing offshore wind farm developments can have a substantial impact on the structuring of coastal marine ecosystems on basin scales.