AGW Observer

Observations of anthropogenic global warming

New research – biosphere (October 10, 2016)

Posted by Ari Jokimäki on October 10, 2016

Some of the latest papers on climate change impacts on biosphere are shown below. First a few highlighted papers with abstracts and then a list of some other papers. If this subject interests you, be sure to check also the other papers – they are by no means less interesting than the highlighted ones.


Population trends influence species ability to track climate change (Ralston et al. 2016)

Abstract: Shifts of distributions have been attributed to species tracking their fundamental climate niches through space. However, several studies have now demonstrated that niche tracking is imperfect, that species’ climate niches may vary with population trends, and that geographic distributions may lag behind rapid climate change. These reports of imperfect niche tracking imply shifts in species’ realized climate niches. We argue that quantifying climate niche shifts and analyzing them for a suite of species reveal general patterns of niche shifts and the factors affecting species’ ability to track climate change. We analyzed changes in realized climate niche between 1984 and 2012 for 46 species of North American birds in relation to population trends in an effort to determine whether species differ in the ability to track climate change and whether differences in niche tracking are related to population trends. We found that increasingly abundant species tended to show greater levels of niche expansion (climate space occupied in 2012 but not in 1980) compared to declining species. Declining species had significantly greater niche unfilling (climate space occupied in 1980 but not in 2012) compared to increasing species due to an inability to colonize new sites beyond their range peripheries after climate had changed at sites of occurrence. Increasing species, conversely, were better able to colonize new sites and therefore showed very little niche unfilling. Our results indicate that species with increasing trends are better able to geographically track climate change compared to declining species, which exhibited lags relative to changes in climate. These findings have important implications for understanding past changes in distribution, as well as modeling dynamic species distributions in the face of climate change.

Phylogenetic conservatism and climate factors shape flowering phenology in alpine meadows (Li et al. 2016)

Abstract: The study of phylogenetic conservatism in alpine plant phenology is critical for predicting climate change impacts; currently we have a poor understanding of how phylogeny and climate factors interactively influence plant phenology. Therefore, we explored the influence of phylogeny and climate factors on flowering phenology in alpine meadows. For two different types of alpine plant communities, we recorded phenological data, including flowering peak, first flower budding, first flowering, first fruiting and the flowering end for 62 species over the course of 5 years (2008–2012). From sequences in two plastid regions, we constructed phylogenetic trees. We used Blomberg’s K and Pagel’s lambda to assess the phylogenetic signal in phenological traits and species’ phenological responses to climate factors. We found a significant phylogenetic signal in the date of all reproductive phenological events and in species’ phenological responses to weekly day length and temperature. The number of species in flower was strongly associated with the weekly day lengths and followed by the weekly temperature prior to phenological activity. Based on phylogenetic eigenvector regression (PVR) analysis, we found a highly shared influence of phylogeny and climate factors on alpine species flowering phenology. Our results suggest the phylogenetic conservatism in both flowering and fruiting phenology may depend on the similarity of responses to external environmental cues among close relatives.

Sea-ice indicators of polar bear habitat (Stern & Laidre, 2016)

Abstract: Nineteen subpopulations of polar bears (Ursus maritimus) are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology – the cycle of biological events – is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat) on its way to the summer minimum or rises above the threshold (advance) on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979–2014) mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from −3 to −9 days decade−1 in spring and from +3 to +9 days decade−1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days) and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of −7 to −19 days decade−1, with larger trends in the Barents Sea and central Arctic Basin. The June–October sea-ice concentration is declining in all regions at rates ranging from −1 to −9 percent decade−1. These sea-ice metrics (or indicators of habitat change) were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in future reports.

Lagging behind: have we overlooked previous-year rainfall effects in annual grasslands? (Dudney et al. 2016)

Abstract: 1.Rainfall is a key determinant of production and composition in arid and semiarid systems. Long-term studies relating composition and water availability primarily focus on current-year precipitation patterns, though mounting evidence highlights the importance of previous-year rainfall particularly in grasslands dominated by perennial species. The extent to which lagged precipitation effects occur in annual grasslands, however, remains largely unexplored.

2.We pair a long-term study with two manipulative experiments to identify patterns and mechanisms of lagged precipitation effects in annual grasslands. The long-term study captured variation in functional group (exotic annual forbs and grasses) abundance and precipitation across eight years at three northern California grassland sites. We then tested whether lagged rainfall effects were created through seed production and litter (residual dry matter) by manipulating rainfall and litter, respectively.

3.Rainfall from the previous-year growing season (both seasonal and total rainfall) shifted functional group abundance. High lagged rainfall was associated with increased grass and decreased forb abundance the following year. Current-year seasonal rainfall also influenced species composition, with winter rain increasing forb and decreasing grass abundance. Lagged precipitation effects were generally stronger for forbs than for grasses. Our experimental studies provided evidence for two mechanisms that contributed to lagged effects in annual grasslands. Higher rainfall increased seed production for grasses, which translated to more germinable seed the following year. Higher rainfall also increased biomass production and residual dry matter, which benefited grasses and reduced forb abundance.

4.Synthesis. Our results highlight the importance of previous-year precipitation in structuring annual community composition and suggest two important biotic pathways, seed rain and RDM, that regulate lagged community responses to rainfall. Incorporating lagged effects into models of grassland diversity and productivity could improve predictions of climate change impacts in annual grasslands.

Effects of high latitude protected areas on bird communities under rapid climate change (Santangeli et al. 2016)

Abstract: Anthropogenic climate change is rapidly becoming one of the main threats to biodiversity, along with other threats triggered by human-driven land-use change. Species are already responding to climate change by shifting their distributions polewards. This shift may create a spatial mismatch between dynamic species distributions and static protected areas (PAs). As protected areas represent one of the main pillars for preserving biodiversity today and in the future, it is important to assess their contribution in sheltering the biodiversity communities they were designated to protect. A recent development to investigate climate-driven impacts on biological communities is represented by the community temperature index (CTI). CTI provides a measure of the relative temperature average of a community in a specific assemblage. CTI value will be higher for assemblages dominated by warm species compared to those dominated by cold-dwelling species. We here model changes in the CTI of Finnish bird assemblages, as well as changes in species densities, within and outside of PAs during the past four decades in a large boreal landscape under rapid change. We show that CTI has markedly increased over time across Finland, with this change being similar within and outside PAs and five to seven times slower than the temperature increase. Moreover, CTI has been constantly lower within than outside of PAs, and PAs still support communities which show colder thermal index than those outside of PAs in the 70s and 80s. This result can be explained by the higher relative density of northern species within PAs than outside. Overall, our results provide some, albeit inconclusive, evidence that PAs may play a role in supporting the community of northern species. Results also suggest that communities are however shifting rapidly, both inside and outside of PAs, highlighting the need for adjusting conservation measures before it’s too late.

Other papers

Impact of temperature and precipitation extremes on the flowering dates of four German wildlife shrub species (Siegmund et al. 2016)

Cyanobacteria in aquaculture systems: linking the occurrence, abundance and toxicity with rising temperatures (Sinden & Sinang, 2016)

Under-ice habitats for Antarctic krill larvae: could less mean more under climate warming? (Melbourne-Thomas et al. 2016)

Responses of land evapotranspiration to Earth’s greening in CMIP5 Earth System Models (Zeng et al. 2016)

Impacts of droughts on the growth resilience of Northern Hemisphere forests (Gazol et al. 2016)

Environmental status of the Gulf of California: A review of responses to climate change and climate variability (Páez-Osuna et al. 2016)

High-resolution tide projections reveal extinction threshold in response to sea-level rise (Field et al. 2016)

Quantifying full phenological event distributions reveals simultaneous advances, temporal stability and delays in spring and autumn migration timing in long-distance migratory birds (Miles et al. 2016)

Can we predict ectotherm responses to climate change using thermal performance curves and body temperatures? (Sinclair et al. 2016)

Ectomycorrhizal fungal response to warming is linked to poor host performance at the boreal-temperate ecotone (Fernandez et al. 2016)

Spatiotemporal variability of stone pine (Pinus pinea L.) growth response to climate across the Iberian Peninsula (Natalini et al. 2016)

Nonlinear, interacting responses to climate limit grassland production under global change (Zhu et al. 2016)

An unprecedented coastwide toxic algal bloom linked to anomalous ocean conditions (McCabe et al. 2016)

Increased activity of lysozyme and complement system in Atlantic halibut exposed to elevated CO2 at six different temperatures (de Souza et al. 2016)

Multisite analysis of land surface phenology in North American temperate and boreal deciduous forests from Landsat (Melaas et al. 2016)

Responses of spring phenology in a fruit tree species (Pyrus sp. cv. Pingguoli) to the changes in surface air temperature in Northeast China (Shen & Kobayashi, 2016)

Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models (Fu et al. 2016)

Decreased photosynthesis and growth with reduced respiration in the model diatom Phaeodactylum tricornutum grown under elevated CO2 over 1800 generations (Li et al. 2016)

Where do they go? The effects of topography and habitat diversity on reducing climatic debt in birds (Gaüzère et al. 2016)

Precipitation, not air temperature, drives functional responses of trees in semi-arid ecosystems (Grossiord et al. 2016)

Relationships between individual-tree mortality and water-balance variables indicate positive trends in water stress-induced tree mortality across North America (Hember et al. 2016)

Disturbances catalyze the adaptation of forest ecosystems to changing climate conditions (Thom et al. 2016)

Extreme climatic events constrain space use and survival of a ground-nesting bird (Tanner et al. 2016)

Spatial and evolutionary parallelism between shade and drought tolerance explains the distributions of conifers in the conterminous United States (Rueda et al. 2016)

Effects of climate change on the distribution of indigenous species in oceanic islands (Azores) (Ferreira et al. 2016)

Northern ragweed ecotypes flower earlier and longer in response to elevated CO2: what are you sneezing at? (Stinson et al. 2016)

Australian vegetation phenology: new insights from satellite remote sensing and digital repeat photography (Moore et al. 2016)

Temporal variability in the thermal requirements for vegetation phenology on the Tibetan plateau and its implications for carbon dynamics (Jin et al. 2016)

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