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Ecosystem Processes and Human Influences Regulate Streamflow Response to Climate Change at Long-Term Ecological Research Sites
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Analyses of long-term records at 35 headwater basins in the United States and Canada indicate that climate change effects on streamflow are not as clear as might be expected, perhaps because of ecosystem processes and human influences. Evapotranspiration was higher than was predicted by temperature in water-surplus ecosystems and lower than was predicted in water-deficit ecosystems. Streamflow was correlated with climate variability indices (e.g., the El Niño–Southern Oscillation, the Pacific Decadal Oscillation, the North Atlantic Oscillation), especially in seasons when vegetation influences are limited. Air temperature increased significantly at 17 of the 19 sites with 20- to 60-year records, but streamflow trends were directly related to climate trends (through changes in ice and snow) at only 7 sites. Past and present human and natural disturbance, vegetation succession, and human water use can mimic, exacerbate, counteract, or mask the effects of climate change on streamflow, even in reference basins. Long-term ecological research sites are ideal places to disentangle these processes.
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Effects of grazing on grassland soil carbon: a global review
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Soils of grasslands represent a large potential reservoir for storing CO2, but this potential likely depends on how grasslands are managed for large mammal grazing. Previous studies found both strong positive and negative grazing effects on soil organic carbon (SOC) but explanations for this variation are poorly developed. Expanding on previous reviews, we performed a multifactorial meta-analysis of grazer effects on SOC density on 47 independent experimen- tal contrasts from 17 studies. We explicitly tested hypotheses that grazer effects would shift from negative to positive with decreasing precipitation, increasing fineness of soil texture, transition from dominant grass species with C3 to C4 photosynthesis, and decreasing grazing intensity, after controlling for study duration and sampling depth. The six variables of soil texture, precipitation, grass type, grazing intensity, study duration, and sampling depth explained 85% of a large variation (`150 g m␣2 yr␣1) in grazing effects, and the best model included significant interactions between precipitation and soil texture (P = 0.002), grass type, and grazing intensity (P = 0.012), and study duration and soil sampling depth (P = 0.020). Specifically, an increase in mean annual precipitation of 600 mm resulted in a 24% decrease in grazer effect size on finer textured soils, while on sandy soils the same increase in precipitation pro- duced a 22% increase in grazer effect on SOC. Increasing grazing intensity increased SOC by 6–7% on C4-dominated and C4–C3 mixed grasslands, but decreased SOC by an average 18% in C3-dominated grasslands. We discovered these patterns despite a lack of studies in natural, wildlife-dominated ecosystems, and tropical grasslands. Our results, which suggest a future focus on why C3 vs. C4-dominated grasslands differ so strongly in their response of SOC to grazing, show that grazer effects on SOC are highly context-specific and imply that grazers in different regions might be managed differently to help mitigate greenhouse gas emissions.
Keywords: carbon sequestration, grasslands, grazing, grazing intensity, precipitation, soil organic carbon, soil texture
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Emerging Techniques for Soil Carbon measurements
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Soil carbon sequestration is one approach to mitigate greenhouse gases. However, to reliably
assess the quantities sequestered as well as the chemical structure of the soil carbon, new
methods and equipment are needed. These methods and equipment must allow large scale
measurements and the construction of dynamic maps. This paper presents results from some
emerging techniques to measure carbon quantity and stability. Each methodology has specific
capabilities and their combined use along with other analytical tools will improve soil organic
matter research. New opportunities arise with the development and application of portable
equipment, based on spectroscopic methods, as laser-induced fluorescence, laser-induced
breakdown spectroscopy and near infrared, for in situ carbon measurements in different
ecosystems. These apparatus could provide faster and lower cost field analyses thus
improving soil carbon contents and quality databases. Improved databases are essential to
model carbon balance, thus reducing the uncertainties generated through the extrapolation of
limited data.
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Evolution of climate niches in European mammals?
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Our ability to predict consequences of climate change is severely impaired by the lack of knowledge on the ability of species to adapt to changing environmental conditions. We used distribution data for 140 mammal species in Europe, together with data on climate, land cover and topography, to derive a statistical description of their realized climate niche. We then compared climate niche overlap of pairs of species, selected on the basis of phylogenetic information. In contrast to expectations, related species were not similar in their climate niche. Rather, even species pairs that had a common ancestor less than 1Ma already display very high climate niche distances. We interpret our finding as a strong inter- specific competitive constraint on the realized niche, rather than a rapid evolution of the fundamental niche. If correct, our results imply a very limited usefulness of climate niche models for the prediction of future mammal distributions.
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Forecasting the response of Earth’s surface to future climatic and land use changes: A review of methods and research needs
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In the future, Earth will be warmer, precipitation events will be more extreme, global mean
sea level will rise, and many arid and semiarid regions will be drier. Human modifications of landscapes
will also occur at an accelerated rate as developed areas increase in size and population density. We now
have gridded global forecasts, being continually improved, of the climatic and land use changes (C&LUC)
that are likely to occur in the coming decades. However, besides a few exceptions, consensus forecasts do
not exist for how these C&LUC will likely impact Earth-surface processes and hazards. In some cases, we
have the tools to forecast the geomorphic responses to likely future C&LUC. Fully exploiting these models
and utilizing these tools will require close collaboration among Earth-surface scientists and Earth-system
modelers. This paper assesses the state-of-the-art tools and data that are being used or could be used to
forecast changes in the state of Earth’s surface as a result of likely future C&LUC. We also propose strategies
for filling key knowledge gaps, emphasizing where additional basic research and/or collaboration
across disciplines are necessary. The main body of the paper addresses cross-cutting issues, including the
importance of nonlinear/threshold-dominated interactions among topography, vegetation, and sediment
transport, as well as the importance of alternate stable states and extreme, rare events for understanding
and forecasting Earth-surface response to C&LUC. Five supplements delve into different scales or process
zones (global-scale assessments and fluvial, aeolian, glacial/periglacial, and coastal process zones) in
detail.
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LandPKS
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LandPKS tools allow users to learn about the land and produce site-specific data at any specific location in the world. The LandPKS mobile app is free to download for Android and iOS devices. Users can then access and download their data in the form of .csv files from the Data Portal.
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Scaling up from gardens: biodiversity conservation in urban environments
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As urbanisation increases globally and the natural environment becomes increasingly fragmented, the
importance of urban green spaces for biodiversity conservation grows. In many countries, private gardens area major component of urban green space and can provideconsiderable biodiversity benefits. Gardens and
adjacent habitats form interconnected networks and a landscape ecology framework is necessary to understand the relationship between the spatial configuration of garden patches and their constituent biodiversity. A scale-dependent tension is apparent in garden management, whereby the individual garden is much smaller than the unit of management needed to retain viable populations. To overcome this, here we suggest mechanisms for encouraging ‘wildlife-friendly’ management of collections of gardens across scales from the neighbourhood to the city.
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Solar energy development impacts on land cover change and protected areas
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Decisions determining the use of land for energy are of exigent concern as land scarcity, the need for ecosystem services, and demands for energy generation have concomitantly increased globally. Utility-scale solar energy (USSE) [i.e., ≥1 megawatt (MW)] development requires large quantities of space and land; however, studies quantifying the effect of USSE on land cover change and protected areas are limited. We assessed siting impacts of >160 USSE installations by technology type [photovoltaic (PV) vs. concentrating solar power (CSP)], area (in square kilometers), and capacity (in MW) within the global solar hot spot of the state of California (United States). Additionally, we used the Carnegie Energy and Environmental Compatibility model, a multiple criteria model, to quantify each installation according to environmental and technical compatibility. Last, we evaluated installations according to their proximity to protected areas, including inventoried roadless areas, endangered and threatened species habitat, and federally protected areas. We found the plurality of USSE (6,995 MW) in California is sited in shrublands and scrublands, comprising 375 km2 of land cover change. Twenty-eight percent of USSE installations are located in croplands and pastures, comprising 155 km2 of change. Less than 15% of USSE installations are sited in “Compatible” areas. The majority of “Incompatible” USSE power plants are sited far from existing transmission infrastructure, and all USSE installations average at most 7 and 5 km from protected areas, for PV and CSP, respectively. Where energy, food, and conservation goals intersect, environmental compatibility can be achieved when resource opportunities, constraints, and trade-offs are integrated into siting decisions.
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Too late for two degrees? Low carbon economy index 2012
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Even doubling our current rate of decarbonisation would still lead to emissions consistent with 6 degrees of
warming by the end of the century. To give ourselves a more than 50% chance of avoiding 2 degrees will
require a six-fold improvement in our rate of decarbonisation.
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Worldwide evidence of a unimodal relationship between productivity and plant species richness
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The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity.
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