Global Change Scenarios Research Articles

Population Dynamics of Wild Mongolian Gerbils: Quadratic Temperature Effects on Survival and Density-Dependent Effects on Recruitment

It has been hypothesized that animal populations respond nonlinearly to the environment, and such responses are important to understand the effects of climate change population dynamics of small mammals in arid environments at northern latitudes. The aim of this study was to test the following hypotheses: (1) that small rodent populations increase as their semiarid habitat conditions improve from low to intermediate levels of temperature or precipitation, and decline beyond the optimum climate because of decreased survival, and (2) that increased population density would result in stronger negative effects on recruitment than on survival. A wild population of Mongolian gerbils (Meriones unguiculatus), a granivorous rodent distributed in Inner Mongolia, China, was live-trapped half-monthly between April and October from 2014 to 2017 and the effects of climate and density on their apparent survival probabilities and recruitment rates were estimated using mark-recapture methods. Increased temperatures initially had a positive effect on population growth rates, and then had negative effects on population growth rates primarily, which was mediated by quadratic effects on survival probabilities, further supporting the optimum habitat hypothesis. Moreover, the increases in temperature had a positive effect on the recruitment of gerbils, whereas population density had a more markedly negative effect on recruitment than on survival. The results of this study suggested that the density-dependent feedback to recruitment may be a primary regulatory mechanism of small mammal populations, and the complex responses of populations to temperature, which is a limiting ecological factor, may raise concerns for the fate of populations of small mammals at northern latitudes, in view of the predicted global climate change scenarios.

Divergent temporal variations in soil microbial attributes under a subtropic afforestation

Soil microorganisms fundamentally regulate biochemical processes of soil organic matter decomposition in terrestrial ecosystems. In this study, we examined seasonal and yearly variations in soil microbial attributes (i.e., total phospholipid fatty acids (PLFAs), bacteria (B) and fungi (F), actinobacteria (ACT), microbial respiration (MR)) and potential controls at two soil depths under conversion from the cropland and uncultivated land to afforested lands (woodland and shrubland) of different years (2015, 2017) in the Danjiangkou Reservoir of subtropical China. The total PLFA (2.29–11.24 ug g−1), B (1.66–6.73 ug g−1) and F (0.32–1.44 ug g−1) biomass did not significantly vary with seasons of 2015, but they were significantly higher in summer (3.73–13.97, 1.49–7.36, 0.47–2.31 ug g−1, respectively) than in winter (1.30–9.73, 0.61–5.79, 0.23–1.49 ug g−1, respectively) of 2017 due to the larger fluctuation in soil moisture between winter and summer of 2017. In contrast, the lower MR (0.58–2.56 mg CO2−1 g soil−1h) in summer compared to winter (0.77–3.77 mg CO2−1 g soil−1h) was observed in 2015 primarily due to higher soil moisture in winter, but the higher MR (0.77–4.42 mg CO2−1 g soil−1h) was detected in summer than that in winter (0.43–2.89 mg CO2−1 g soil−1h) of 2017, which was closely related to lower soil moisture together with larger PLFA biomass in summer. The MR significantly changed with seasons in afforested lands, but it did not significantly vary with seasons in cropland and uncultivated land. Conversely, the MR/total PLFAs ratios significantly changed with seasons in cropland and uncultivated land, but it did not significantly vary with seasons in afforested lands. Collectively, our results revealed the different temporal pattern of soil microbial community composition under afforestation, thereby providing very useful information for governments to better manage and protect agricultural land use in future global change scenarios.

Productivity Screening of Common Bean (Phaseolus vulgaris L.) Varieties and Agronomic Trait Eco-Seasonal Morphological and Physiological Characterization

The productivity of beans (Phaseolus vulgaris L) has been found to be influenced by biophysical stresses like ecological variations, genotype, climate, pests, and soil fertility. This has reduced bean productivity by 25% in some cases. Hence, research to improve bean varieties and the consequential assessment of their field performance is necessitated by global climate change scenarios. The eco-matching of genotypes in the midst of emerging issues like climate change and global warming has serious economic and food security implications. This research evaluated genotype, seasonal, ecological, and productivity variations of four bean varieties in three diverse ecological zones at the Mua Hills in Machakos County in Kenya. All the experiments were arranged in a Complete Randomized Block Design (RCBD). The research obtained data on growth (leaf numbers, plant heights, plant maturity times), seed parameters (seed water imbibition, shape, colour) and yield parameters (number of pods, pod weight, 100 seed weight) until harvesting time. Data collected were subjected to Multivariate analysis of variance (ANOVA) at P≤0.05 and means separated using the LSD significant difference test at P≤0.05. The study found that there were significant bean genotype and seasonal and eco-sensitive variation differences at P≤0.05. The economically valuable trait of 100 seed weight correlated positively with other traits in all zones. Therefore, bean varieties are season and eco-sensitive due to genotype, water stress, and current climate change scenarios. Hence, breeding experiments should endeavour to release varieties that have undergone seasonal ecological screening as exacerbated by the need for high productivity

Ecological clusters of soil taxa within bipartite networks are highly sensitive to climatic conditions in global drylands.

Determining the influence of climate in driving the global distribution of soil microbial communities is fundamental to help predict potential shifts in soil food webs and ecosystem functioning under global change scenarios. Herein, we used a global survey including 80 dryland ecosystems from six continents, and found that the relative abundance of ecological clusters formed by taxa involved in bacteria-fungi and bacteria-cercozoa bipartite networks was highly sensitive to changes in temperature and aridity. Importantly, such a result was maintained when controlling for soil, geographical location and vegetation attributes, being pH and soil organic carbon important determinants of the relative abundance of the ecological clusters. We also identified potential global associations between important soil microbial taxa, which can be useful to support the conservation of terrestrial ecosystems under global change scenarios. Our results suggest that increases in temperature and aridity such as those forecasted for the next decades in drylands could potentially lead to drastic changes in the community composition of functionally important bipartite networks within soil food webs. This could have important but unknown implications for the provision of key ecosystem functions and associated services driven by the organisms forming these networks if other taxa cannot cope with them. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'.

Island and Mountain Ecosystems as Testbeds for Biological Control in the Anthropocene

For centuries, islands and mountains have incited the interest of naturalists, evolutionary biologists and ecologists. Islands have been the cradle for biogeography and speciation theories, while mountain ranges have informed how population adaptation to thermal floors shapes the distribution of species globally. Islands of varying size and mountains’ altitudinal ranges constitute unique “natural laboratories” where one can investigate the effects of species loss or global warming on ecosystem service delivery. Although invertebrate pollination or seed dispersal processes are steadily being examined, biological control research is lagging. While observations of a wider niche breadth among insect pollinators in small (i.e., species-poor) islands or at high (i.e., colder) altitudes likely also hold for biological control agents, such remains to be examined. In this Perspective piece, we draw on published datasets to show that island size alone does not explain biological control outcomes. Instead, one needs to account for species’ functional traits, habitat heterogeneity, host community make-up, phenology, site history or even anthropogenic forces. Meanwhile, data from mountain ranges show how parasitism rates of Noctuid moths and Tephritid fruit flies exhibit species- and context-dependent shifts with altitude. Nevertheless, future empirical work in mountain settings could clarify the thermal niche space of individual natural enemy taxa and overall thermal resilience of biological control. We further discuss how global databases can be screened, while ecological theories can be tested, and simulation models defined based upon observational or manipulative assays in either system. Doing so can yield unprecedented insights into the fate of biological control in the Anthropocene and inform ways to reinforce this vital ecosystem service under global environmental change scenarios.

Wildfire decouples soil multi-element cycles: Contributions of legacy effects and temporal variations

High-severity wildfires may lead to significant impacts on biogeochemical cycling both by burning biomass and by fire legacies. However, the legacy effects of wildfires on multiple soil element cycles across temporal trajectories have rarely been discussed. Here, we evaluated the availability and stability of seven essential soil elements and their stoichiometric ratios, as well as the coupling of multiple and individual elements, over more than two years in a half-mature, severely burnt (SB) artificial Pinus tabuliformis Carr. forest in North China (Beijing) in comparison with the unburnt (UB) control. Despite element concentrations jumped up and down remarkably during the first few months, results showed that the average availability and stability of all elements in soils of the SB site were lower than those of the UB site and legacy effects of fire were consistently significant on available nitrogen (N), phosphorus (P) and sodium. Temporal trajectories (months to years) varied amongst elements, and organic carbon (C) and N depleted more than other elements did. High levels (i.e. above the null model threshold) of multi-element coupling in soils of the UB site were maintained during our monitoring periods. By contrast, a reduction in the degree of element coupling was detected over time in soils of the SB site, which was concomitant with the core role of C and the great variability of P. Fire- and time-induced shifts in cation exchange capacity, acid phosphatase activity, capillary porosity and aggregate fraction dominated the uncoupling of multiple soil elements, implying the critical contributions of fire legacy effects and temporal variations. These responses have important implications for the consideration of additional long-term studies because such biogeochemical decoupling of elements may have unpredicted consequences under global change scenarios. Meanwhile, this work is helpful to predict the direction of ecosystem succession and to provide scientific evidence for management practices.

Resilient consumers accelerate the plant decomposition in a naturally acidified seagrass ecosystem.

Anthropogenic stressors are predicted to alter biodiversity and ecosystem functioning worldwide. However, scaling up from species to ecosystem responses poses a challenge, as species and functional groups can exhibit different capacities to adapt, acclimate, and compensate under changing environments. We used a naturally acidified seagrass ecosystem (the endemic Mediterranean Posidonia oceanica) as a model system to examine how ocean acidification (OA) modifies the community structure and functioning of plant detritivores, which play vital roles in the coastal nutrient cycling and food web dynamics. In seagrass beds associated with volcanic CO2 vents (Ischia, Italy), we quantified the effects of OA on seagrass decomposition by deploying litterbags in three distinct pH zones (i.e., ambient, low, extreme low pH), which differed in the mean and variability of seawater pH. We replicated the study in two discrete vents for 117 days (litterbags sampled on day 5, 10, 28, 55, and 117). Acidification reduced seagrass detritivore richness and diversity through the loss of less abundant, pH-sensitive species but increased the abundance of the dominant detritivore (amphipod Gammarella fucicola). Such compensatory shifts in species abundance caused more than a threefold increase in the total detritivore abundance in lower pH zones. These community changes were associated with increased consumption (52%-112%) and decay of seagrass detritus (up to 67% faster decomposition rate for the slow-decaying, refractory detrital pool) under acidification. Seagrass detritus deployed in acidified zones showed increased N content and decreased C:N ratio, indicating that altered microbial activities under OA may have affected the decay process. The findings suggest that OA could restructure consumer assemblages and modify plant decomposition in blue carbon ecosystems, which may have important implications for carbon sequestration, nutrient recycling, and trophic transfer. Our study highlights the importance of within-community response variability and compensatory processes in modulating ecosystem functions under extreme global change scenarios.

Key Strategies Underlying the Adaptation of Mongolian Scots Pine (Pinussylvestris var. mongolica) in Sandy Land under Climate Change: A Review

Forest degradation and mortality have been widely reported in the context of increasingly significant global climate change. As the country with the largest total tree plantation area globally, China has a great responsibility in forestry management to cope with climate change effectively. Mongolian Scots pine (Pinus sylvestris var. mongolica) was widely introduced from its natural sites in China into several other sandy land areas for establishing shelterbelt in the Three-North Shelter Forest Program, scoring outstanding achievements in terms of wind-breaking and sand-fixing. Mongolian Scots pine plantations in China cover a total area of ~800,000 hectares, with the eldest trees having >60 years. However, plantation trees have been affected by premature senescence in their middle-age stages (i.e., dieback, growth decline, and death) since the 1990s. This phenomenon has raised concerns about the suitability of Mongolian Scots pine to sandy habitats and the rationality for further afforestation, especially under the global climate change scenario. Fortunately, dieback has occurred only sporadically at specific sites and in certain years and has not spread to other regions in northern China; nevertheless, global climate change has become increasingly significant in that region. These observations reflect the strong drought resistance and adaptability of Mongolian Scots pines. In this review, we summarized the most recent findings on the ecohydrological attributes of Mongolian Scots pine during its adaptation to both fragile habitats and climate change. Five main species-specific strategies (i.e., opportunistic water absorb strategy, hydraulic failure risk avoidance strategy, water conservation strategy, functional traits adjustment strategy, rapid regeneration strategy) were summarized, providing deep insights into the tree–water relationship. Overall, the findings of this study can be applied to improve plantation management and better cope with climate-change-related drought stress.

Does pH matter for ecosystem multifunctionality? An empirical test in a semi‐arid grassland on the Loess Plateau

Abstract Globally, higher inputs of acid deposition and anthropogenic reactive nitrogen cause lower pH in soils, that is, soil acidification, which may broadly influence both above‐ and below‐ground biota and their habitats. However, we know little about the consequences of soil acidification for a wide range of ecosystem functions and services (i.e. ecosystem multifunctionality). Here, we examined the impacts of short‐term soil acidification on 19 ecosystem functions relevant to ecosystem primary productivity and the cycling and/or storage of soil carbon (C), nitrogen (N) and phosphorus (P) using a 2‐year acid addition field experiment in a semi‐arid grassland on the Loess Plateau, China. We further assessed the potential pathways through which plant diversity and soil processes drive ecosystem multifunctionality (hereafter, EMF, EMF‐productivity, EMF‐C, EMF‐N, EMF‐P). We found that soil acidification suppressed 15 of the 19 individual ecosystem functions. By accounting for other biotic and abiotic confounding variables, we found that soil pH remains to be the dominant one explaining the variation in EMF, EMF‐C and EMF‐N. The underlying mechanisms of soil pH driving multifunctionality varied substantially among the groups of multifunctionality. Specifically, plant‐related variables (i.e. species richness and abundance) exhibited stronger mediating effects on EMF‐productivity and EMF‐C than did soil properties (i.e. soil K+, Ca2+, Mg2+ and Na+ ions) and microbial‐related variables (i.e. microbial biomass C and N). Our findings provide empirical evidence that short‐term soil acidification could have greater negative effects on ecosystem multifunctionality than expected in the arid and semi‐arid areas where alkaline soils are commonly seen. This study also indicates that more attention should be paid to the biological mechanisms mediating multifunctional ecosystems under a global change scenario in the future. Read the free Plain Language Summary for this article on the Journal blog.

Contributing to healthy forests: Social preferences for pest and disease mitigation programs in Spain

In a scenario of global change, with increasing temperatures and extreme climatic events, healthy forests are at risk. Forests have to fight several types of biotic and abiotic stress. Prospective scenarios warn of the negative effects that forests will suffer in upcoming decades (drought, fires, pests, diseases, etc.), consequently making it necessary to implement actions that can not only prevent the attack of biotic agents such as fungi and insects but also improve the resilience of forest systems. Such warning scenarios transcend the scientific sphere, and as such, Spanish society has previously expressed considerable concern about the appearance of pests and diseases caused by biotic agents. This article therefore analyzes the social preferences for pest and disease mitigation programs in Spanish forests. A discrete choice experiment was consequently carried out, and the willingness to pay was estimated for various characteristics of mitigation programs. The results show that society positively values these programs, mainly when they are applied in relatively nearby forests, when they are targeted at mixed forests, and when there is low uncertainty about their effectiveness. Conversely, the self-management of subsidies by forest owners is rejected, with a preference for funds being managed by regional public authorities.

Temperature responsiveness of soil carbon fractions, microbes, extracellular enzymes and CO2 emission: mitigating role of texture.

The interaction of warming and soil texture on responsiveness of the key soil processes i.e. organic carbon (C) fractions, soil microbes, extracellular enzymes and CO2 emissions remains largely unknown. Global warming raises the relevant question of how different soil processes will respond in near future, and what will be the likely regulatory role of texture? To bridge this gap, this work applied the laboratory incubation method to investigate the effects of temperature changes (10–50 °C) on dynamics of labile, recalcitrant and stable C fractions, soil microbes, microbial biomass, activities of extracellular enzymes and CO2 emissions in sandy and clayey textured soils. The role of texture (sandy and clayey) in the mitigation of temperature effect was also investigated. The results revealed that the temperature sensitivity of C fractions and extracellular enzymes was in the order recalcitrant C fractions > stable C fractions > labile C fractions and oxidative enzymes > hydrolytic enzymes. While temperature sensitivity of soil microbes and biomass was in the order bacteria > actinomycetes > fungi ≈ microbial biomass C (MBC) > microbial biomass N (MBN) > microbial biomass N (MBP). Conversely, the temperature effect and sensitivity of all key soil processes including CO2 emissions were significantly (P < 0.05) higher in sandy than clayey textured soil. Results confirmed that under the scenario of global warming and climate change, soils which are sandy in nature are more susceptible to temperature increase and prone to become the CO2-C sources. It was revealed that clayey texture played an important role in mitigating and easing off the undue temperature influence, hence, the sensitivity of key soil processes.

Phosphorus addition decreases plant lignin but increases microbial necromass contribution to soil organic carbon in a subalpine forest.

Increasing phosphorus (P) inputs induced by anthropogenic activities have increased P availability in soils considerably, with dramatic effects on carbon (C) cycling and storage. However, the underlying mechanisms via which P drives plant and microbial regulation of soil organic C (SOC) formation and stabilization remain unclear, hampering the accurate projection of soil C sequestration under future global change scenarios. Taking the advantage of an 8-year field experiment with increasing P addition levels in a subalpine forest on the eastern Tibetan Plateau, we explored plant C inputs, soil microbial communities, plant and microbial biomarkers, as well as SOC physical and chemical fractions. We found that continuous P addition reduced fine root biomass, but did not affect total SOC content. P addition decreased plant lignin contribution to SOC, primarily from declined vanillyl-type phenols, which was coincided with a reduction in methoxyl/N-alkyl C by 2.1%-5.5%. Despite a decline in lignin decomposition due to suppressed oxidase activity by P addition, the content of lignin-derived compounds decreased because of low C input from fine roots. In contrast, P addition increased microbial (mainly fungal) necromass and its contribution to SOC due to the slower necromass decomposition under reduced N-acquisition enzyme activity. The larger microbial necromass contribution to SOC corresponded with a 9.1%-12.4% increase in carbonyl C abundance. Moreover, P addition had no influence on the slow-cycing mineral-associated organic C pool, and SOC chemical stability indicated by aliphaticity and recalcitrance indices. Overall, P addition in the subalpine forest over 8 years influenced SOC composition through divergent alterations of plant- and microbial-derived C contributions, but did not shape SOC physical and chemical stability. Such findings may aid in accurately forecasting SOC dynamics and their potential feedbacks to climate change with future scenarios of increasing soil P availability in Earth system models.

Distribución y conservación de las papayas de altura del noroeste argentino bajo escenarios de cambio global

Wild species related to crops are a source of genes for improving crop tolerance of biotic and abiotic stresses. Vasconcellea quercifolia and V. glandulosa are wild relatives of papaya (Carica papaya). They are the southernmost-distributed members of the genus and have traits related to tolerance of temperature and precipitation seasonality. Climate and land-use changes, however, are threatening their persistence. Our objectives were to identify priority ex situ conservation areas based on the potential distribution of both species in northwestern Argentina under global change scenarios. The potential distribution of Vasconcellea spp. was modeled using occurrence data and five bioclimatic non-correlated variables. Distribution range shifts were assessed in two climate change scenarios for the year 2050, considering land-use changes. Gap analysis methodology was applied, and conservation priorities were identified by an integrated approach of conservation strategies. Vasconcellea quercifolia has a wider habitat suitability area than V. glandulosa, and the effect of land- use change on distribution was higher for the former than latter species. Conversely, climate change would be more negative on V. glandulosa than V. quercifolia, and the synergic effect of both climate and land-use changes would be higher for V. quercifolia than V. glandulosa. According to gap analysis, both Vasconcellea spp. are high priority species for further germplasm collection. We identified priority areas for ex situ conservation.

Climatic control on the Holocene hydrology of a playa-lake system in the western Mediterranean

Evaporitic lakes such as playa-lakes are characteristic of many arid regions and are unique environments with respect to fauna and flora, while being very vulnerable to climate and environmental fluctuations and threatened by the current global change scenario. Water balance oscillations in these systems can trigger the precipitation or dissolution of different evaporitic minerals, negatively impacting local biodiversity and economic activities. Here, we study the sedimentary record of a small saline pond from a playa-lake complex in southwestern Iberia in order to reconstruct the paleohydrological evolution of this area and assess potential anthropogenic disturbances. The different proxies studied in the ∼11.9 ky old sedimentary record of the Laguna de la Ballestera suggest that the greatest lake extension and the highest water levels occurred during the Early Holocene, pointing to the wettest period of the record. Climate transitioned towards more arid conditions during the Middle Holocene, and even more dramatically during the Late Holocene. In this last stage the wetland surface and the water level largely diminished and gypsum precipitation gradually increased pointing towards a negative precipitation/evapotranspiration balance and lowest water levels. Summer desiccation likely occurred under this scenario, especially after ∼1.0–0.9 cal ky BP coeval with the Medieval Climate Anomaly, when gypsum content started to rise abruptly. However, this significant gypsum precipitation was only associated with a massive drop in the siliciclastic content and scarce carbonates (dolomite and calcite) during the last ∼400 years. This evidence suggests a shift from a (semi) permanent to a temporal/seasonal hydrological regime. The environmental evolution of this wetland responded to the general climatic evolution of the western Mediterranean during the Holocene, being mostly controlled by changes in insolation. Our data also show that the environmental response of the studied wetland to natural climate variations was only significantly disturbed by human activities since the 20th century, especially in the second half of the century, deduced by abrupt fluctuations in the siliciclastic, gypsum and organic content in the sediments, as well as by the enhanced sedimentary accumulation rates, probably as a response to changes in the hydroperiod of the lake and in the catchment land use.

Wood Formation under Changing Environment: Omics Approaches to Elucidate the Mechanisms Driving the Early-to-Latewood Transition in Conifers

The global change scenarios highlight the urgency of clarifying the mechanisms driving the determination of wood traits in forest trees. Coniferous xylem is characterized by the alternation between earlywood (EW) and latewood (LW), on which proportions the wood density depend, one of the most important mechanical xylem qualities. However, the molecular mechanisms triggering the transition between the production of cells with the typical features of EW to the LW are still far from being completely elucidated. The increasing availability of omics resources for conifers, e.g., genomes and transcriptomes, would lay the basis for the comprehension of wood formation dynamics, boosting both breeding and gene-editing approaches. This review is intended to introduce the importance of wood formation dynamics and xylem traits of conifers in a changing environment. Then, an up-to-date overview of the omics resources available for conifers was reported, focusing on both genomes and transcriptomes. Later, an analysis of wood formation studies using omics approaches was conducted, with the aim of elucidating the main metabolic pathways involved in EW and LW determination. Finally, the future perspectives and the urgent needs on this research topic were highlighted.

Assessment of Paracetamol Toxic Effects under Varying Seawater pH Conditions on the Marine Polychaete Hediste diversicolor Using Biochemical Endpoints.

Simple SummaryContext of climate change is being widely studied, nevertheless its effects in the toxicity of other contaminants have been poorly study. Particularly, the effects of ocean acidification on the modulation of pharmaceutical absorption and consequent effects, have not been extensively addressed before. In this study, we aimed to assess the effects of ocean acidification (specifically pH values of 8.2, 7.9, and 7.6) combined with paracetamol exposure (0, 30, 60, and 120 µg/L) on the polychaeta Hediste diversicolor. To do so, specific biomarkers were measured namely (CAT), glutathione S-transferases (GSTs), acetylcholinesterase (AChE), and cyclooxygenase (COX) activities, as well as thiobarbituric acid reactive substance (TBARS), were quantified to serve as ecotoxicological endpoints. Alterations of CAT, and GSTs activities, and TBARS levels indicate an alteration in redox balances. Differences in exposed pH levels indicate the possible modulation of the absorption of this pharmaceutical in ocean acidifications scenarios. Alterations in AChE were only observed following paracetamol exposure, not being altered by media pH. Hereby obtained results suggest that seawater acidification is detrimental to marine wildlife, since it may enhance toxic effects caused by environmental realistic concentrations of pharmaceuticals. This work is crucial to understand the potential effects of pharmaceuticals in a climate change scenario.Increasing atmospheric carbon dioxide (CO2) levels are likely to lower ocean pH values, after its dissolution in seawater. Additionally, pharmaceuticals drugs are environmental stressors due to their intrinsic properties and worldwide occurrence. It is thus of the utmost importance to assess the combined effects of pH decreases and pharmaceutical contamination, considering that their absorption (and effects) are likely to be strongly affected by changes in oceanic pH. To attain this goal, individuals of the marine polychaete Hediste diversicolor were exposed to distinct pH levels (8.2, 7.9, and 7.6) and environmentally relevant concentrations of the acidic drug paracetamol (PAR: 0, 30, 60, and 120 µg/L). Biomarkers such as catalase (CAT), glutathione S-transferases (GSTs), acetylcholinesterase (AChE), and cyclooxygenase (COX) activities, as well as peroxidative damage (through thiobarbituric acid reactive substance (TBARS) quantification), were quantified to serve as ecotoxicological endpoints. Data showed a general increase in CAT and a decrease in GST activities (with significant fluctuations according to the tested conditions of PAR and pH). These changes are likely to be associated with alterations of the redox cycle driven by PAR exposure. In addition, pH levels seemed to condition the toxicity caused by PAR, suggesting that the toxic effects of this drug were in some cases enhanced by more acidic conditions. An inhibition of AChE was observed in animals exposed to the highest concentration of PAR, regardless of the pH value. Moreover, no lipid peroxidation was observed in most individuals, although a significant increase in TBARS levels was observed for polychaetes exposed to the lowest pH. Finally, no alterations of COX activities were recorded on polychaetes exposed to PAR, regardless of the pH level. The obtained results suggest that seawater acidification is detrimental to marine wildlife, since it may enhance toxic effects caused by environmental realistic concentrations of acidic drugs, such as PAR. This work was crucial to evidence that ocean acidification, in the context of a global change scenario of increased levels of both atmospheric and oceanic CO2, is a key factor in understanding the putative enhanced toxicity of most pharmaceutical drugs that are of an acidic nature.

Responses to defoliation of Robinia pseudoacacia L. and Sophora japonica L. are soil water condition dependent

Key messageDefoliation significantly affected biomass allocation of Robinia pseudoacacia L. and Sophora japonica L., but leaf physiology readjusted to control levels at the end of the experiment. Considering carbon or sink limitation and relative height growth rate, defoliated R. pseudoacacia grew faster than S. japonica under well-watered conditions, while defoliated S. japonica and R. pseudoacacia had similar performance under drought conditions.ContextClimate change may result in increases of both drought intensity and insect survival, thereby affecting both exotic and native trees in warm temperate forests.AimsIn this study, we examined the interaction effects of defoliation and drought on an exotic species Robinia pseudoacacia and a native species Sophora japonica in a warm temperate area, to provide a theoretical basis for predicting the distribution and dynamics of the two species under future climate change.MethodsIn a greenhouse, both species were exposed to three soil moisture (75%, 55%, and 35% of field capacity) and three defoliation treatments (no defoliation, 50% defoliation, and 100% defoliation). Leaf physiology, biomass, and non-structural carbohydrate were determined.ResultsLeaf physiology of defoliated trees did not differ from controls trees, but defoliated seedlings allocated relatively more resources to the leaves at the end of the experiment. In well-watered conditions, defoliated R. pseudoacacia was not carbon or sink limited and defoliated S. japonica was carbon limited, while defoliated individuals of the two species were sink limited under drought. Defoliated R. pseudoacacia grow more rapidly than S. japonica in well-watered conditions. Defoliated R. pseudoacacia had a similar growth rate to S. japonica in drought.ConclusionsDefoliation clearly affects biomass allocation of the two species, but not leaf physiology. Considering the carbon or sink limitation, the growth of S. japonica and R. pseudoacacia may be limited by future global climate change scenarios.

Comparing methods that quantify forest disturbances in the United States' national forest inventory.

Forest disturbances play a critical role in ecosystem dynamics. However, the methods for quantifying these disturbances at broad scales may underestimate disturbances that affect individual trees. Utilizing individual tree variables may provide early disturbance detection that directly affects tree demographics and forest dynamics. The goals of this study were to (1) describe different methods for quantifying disturbances at individual tree and condition-level scales, (2) compare the differences between disturbance variables, and (3) provide a methodology for selecting an appropriate disturbance variable from national forest inventories for diverse applications depending on user needs. To achieve these goals, we used all the remeasurements available from the USDA Forest Inventory and Analysis (FIA) database since the start of the annual inventory for the lower 48 US states. Variables used included disturbance code, treatment code, agent of mortality, and damage code. Chi-square tests of independence were used to verify how the choice of the variable that represents disturbance affects its magnitude. Disturbed plots, as classified by each disturbance variable, were mapped to observe their spatial distribution. We found that the Chi-square tests were significant when using all the states and comparing each state individually, indicating that different results exist depending on which variable is used to represent disturbance. Our results will be a useful tool to help researchers measure the magnitude and scale of disturbance since the manner in which disturbances are categorized will impact forest management plans, national and international reports of forest carbon stocks, and sequestration potential under future global change scenarios.

Projections of rainfall erosivity in climate change scenarios for the largest watershed within Brazilian territory

Global climate change can potentially threaten agricultural production due to endangered natural resources, such as rainfall patterns. Thus, extreme rainfall events can cause greater rainfall erosivity, consequently, greater soil erosion. Conversely, a reduction in rainfall amount can lead to water scarcity for the agriculture production process. This way, it is a foremost need to model climatic conditions under global climate change scenarios, particularly in places where rainfall data tends to increase. This work aimed to project rainfall erosivity in the major Brazilian watershed, the Tocantins-Araguaia river basin, throughout the 21st century under two Intergovernmental Panel for Climate Change Fifth Assessment Report (IPCC AR5) Scenarios, the Representative Concentration Pathways, RCP4.5 and RCP8.5 scenarios. This study uses the downscaling of four global climate models of the Coupled Model Intercomparison Project (CMIP5) by the Eta regional climate model, used by the Brazilian National Institute for Space Research. The average rainfall erosivity was calculated based on the Modified Fournier Index in three periods of 30-year length throughout the 21st century. Time series of R-factor were analyzed at rain gauge station points overlapping regional model grid cells over the basin for the 1961–2099 period. Projections indicated lower annual average rainfall erosivity values in comparison with historical data. Estimated mean rainfall erosivity values were 10,977.69 ± 526 MJ mm ha−1 h−1 yr−1 for the RCP4.5 scenario, and 10,379.71 ± 723 MJ mm ha−1 h−1 yr−1 for the most pessimistic climate change scenario, RCP8.5. The largest reductions of the mean R-factor reached 5,5% for the multi-model ensemble projections for near future, and 15.4% for the ensemble projections models for long-term, with the greatest decreasing trends under RCP8.5. Reductions greater than 2,000 MJ mm ha−1 h−1 are expected throughout the 21st century according to multi-model ensemble projections models under RCP8.5 scenario in most of the watershed. Decreasing rainfall erosivity factor in both RCP scenarios was due to a lower rainfall depth. However, the value of rainfall erosivity is still considered high and should be taken into account in soil conservation practices. Furthermore, the smaller rainfall amount indicates a possible reduction in water availability for crops of longer cycle, and increase in spatial variability of less intense rainfall.

CONSERVATION OF IMPERIL ORCHIDS: CLESIOCENTRON PALLENS (CATHCART EX LINDL.) PEARCE &amp; CRIBB AND PHALEONOPSIS MANNII RCHB.F. THROUGH IN VITRO SEED PROPAGATION

Cleisocentron pallens and Phalaenopsis mannii, two spectacular orchids of North East India having highly medicinal and ornamental values with prominent existence in APENDIX-II of CITES. The present scenario of habitat destruction, unsustainable harvesting and global climate change is affecting the distribution of orchids, which leads to rapid depletion from nature. The study deals with mass multiplication of C. pallens and P mannii through in-vitro seed propagation for future conservation strategies. In C. pallens, highest germination percentage (89.35%) of was observed in Mitra medium. The maximum number (11.2±1.75 cm) and length (4.75±0.58 cm) of shoot were observed in 1.5 mg l-1 BAP. Otherwise, medium containing 1.5 mgl-1 IBA showed highest number (7.3±1.33) with 4.67±1.71 cm length of root were recorded. MS media exhibited the best proliferation rates (88.6%) in P. mannii, although highest number (12.5 ±3.62) and (4.01±0.66) length of shoot found in Mitra medium supplemented with 1.5 mg/l BAP. Activated Charcoal powder plays an important role in root formation and phenolic compound exudation). Maximum (4.4±0.69) number with an average length (5.85±0.95) of root was observed in medium supplemented with 1.5mgl-1 IBA. The seedlings showed better survivality and growth increment in potting medium Brick chips: Charcoal: Sphagnum moss (1:1:2) for both the species in green house condition. Seed derived protocorm like bodies could be successfully applied for mass multiplication intended for ex situ conservation.