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Soil Health Institute
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The Soil Health Institute is a non-profit whose mission is to safeguard and enhance the vitality and productivity of soil through scientific research and advancement. The Institute works with its many stakeholders to identify gaps in research and adoption; develop strategies, networks and funding to address those gaps; and ensure beneficial impact of those investments to agriculture, the environment and society.
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Soil organic matter turnover is governed by accessibility not recalcitrance
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Mechanisms to mitigate global climate change by sequestering carbon (C) in different ‘sinks’ have been proposed as at least temporary measures. Of the major global C pools, terrestrial ecosystems hold the potential to capture and store substantially increased volumes of C in soil organic matter (SOM) through changes in management that are also of benefit to the multitude of ecosystem services that soils provide. This potential can only be realized by determining the amount of SOM stored in soils now, with subsequent quantification of how this is affected by management strate- gies intended to increase SOM concentrations, and used in soil C models for the prediction of the roles of soils in future climate change. An apparently obvious method to increase C stocks in soils is to augment the soil C pools with the longest mean residence times (MRT). Computer simulation models of soil C dynamics, e.g. RothC and Century, partition these refractory constituents into slow and passive pools with MRTs of centuries to millennia. This partition- ing is assumed to reflect: (i) the average biomolecular properties of SOM in the pools with reference to their source in plant litter, (ii) the accessibility of the SOM to decomposer organisms or catalytic enzymes, or (iii) constraints imposed on decomposition by environmental conditions, including soil moisture and temperature. However, con- temporary analytical approaches suggest that the chemical composition of these pools is not necessarily predictable because, despite considerable progress with understanding decomposition processes and the role of decomposer organisms, along with refinements in simulation models, little progress has been made in reconciling biochemical properties with the kinetically defined pools. In this review, we will explore how advances in quantitative analytical techniques have redefined the new understanding of SOM dynamics and how this is affecting the development and application of new modelling approaches to soil C.
Keywords: C isotopes, decomposition, recalcitrance, soil C models, soil microorganisms, soil organic matter
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Soil Temperature following Logging-Debris Manipulation and Aspen Regrowth in Minnesota: Implications for Sampling Depth and Alteration of Soil Processes
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Soil temperature is a fundamental controller of processes influencing the
transformation and flux of soil C and nutrients following forest harvest. Soil
temperature response to harvesting is influenced by the amount of logging
debris (biomass) removal that occurs, but the duration, magnitude, and depth
of influence is unclear. Logging debris manipulations (none, moderate, and
heavy amounts) were applied following clearcut harvesting at four aspendominated
(Populus tremuloides Michx.) sites in northeastern Minnesota, and
temperature was measured at 10-, 30-, and 50-cm depths for two growing
seasons. Across sites, soil temperature was significantly greater at all sample
depths relative to uncut forest in some periods of each year, but the increase
was reduced with increasing logging-debris retention. When logging debris
was removed compared to when it was retained in the first growing season,
mean growing season soil temperatures were 0.9, 1.0, and 0.8°C greater at
10-, 30-, and 50-cm depths, respectively. These patterns were also observed
early in the second growing season, but there was no discernible difference
among treatments later in the growing season due to the modifying effect of
rapid aspen regrowth. Where vegetation establishment and growth occurs
quickly, effects of logging debris removal on soil temperature and the processes
influenced by it will likely be short-lived. The significant increase in
soil temperature that occurred in deep soil for at least 2 yr after harvest
supports an argument for deeper soil sampling than commonly occurs in
experimental studies.
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Soil warming, carbon–nitrogen interactions, and forest carbon budgets
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Soil warming has the potential to alter both soil and plant processes that affect carbon storage in forest ecosystems. We have quantified these effects in a large, long-term (7-y) soil-warming study in a deciduous forest in New England. Soil warming has resulted in carbon losses from the soil and stimulated carbon gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen into the soil solution to support the observed increases in plant carbon storage. Although soil warming has resulted in a cumulative net loss of carbon from a New England forest relative to a control area over the 7-y study, the annual net losses generally decreased over time as plant carbon storage increased. In the seventh year, warming-induced soil carbon losses were almost totally compensated for by plant carbon gains in response to warming. We attribute the plant gains primarily to warming- induced increases in nitrogen availability. This study underscores the importance of incorporating carbon–nitrogen interactions in atmosphere–ocean–land earth system models to accurately simulate land feedbacks to the climate system.
climate system feedbacks | ecological stoichiometry | forest carbon budget | forest nitrogen budget | global climate change
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Solem 1974.pdf
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SIM-SPA
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Solem 1975.pdf
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SIM-SPA
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Solomatina 1981.pdf
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SOME REFLECTIONS ON CLIMATE CHANGE, GREEN GROWTH ILLUSIONS AND DEVELOPMENT SPACE
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Many economists and policy makers advocate a fundamental shift towards “green growth” as the new, qualitatively-different growth paradigm, based on enhanced material/resource/energy efficiency and drastic changes in the energy mix. “Green growth” may work well in creating new growth impulses with reduced environmental load and facilitating related technological and structural change. But can it also mitigate climate change at the required scale (i.e. significant, absolute and permanent decline of GHG emissions at global level) and pace? This paper argues that growth, technological, population-expansion and governance constraints as well as some key systemic issues cast a very long shadow on the “green growth” hopes. One should not deceive oneself into believing that such evolutionary (and often reductionist) approach will be sufficient to cope with the complexities of climate change. It may rather give much false hope and excuses to do nothing really fundamental that can bring about a U-turn of global GHG emissions. The proponents of a resource efficiency revolution and a drastic change in the energy mix need to scrutinize the historical evidence, in particular the arithmetic of economic and population growth. Furthermore, they need to realize that the required transformation goes beyond innovation and structural changes to include democratization of the economy and cultural change. Climate change calls into question the global equality of opportunity for prosperity (i.e. ecological justice and development space) and is thus a huge developmental challenge for the South and a question of life and death for some developing countries (who increasingly resist the framing of climate protection versus equity).
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Sometimes, the simplest things can help wildlife
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Sad to say, but that wide-open home on the range that Bing Crosby sings about in Brewster Higley’s “Home on the Range” has been steadily diminishing with every passing decade as the Western landscape has been sliced and diced by roads and barbed-wire fences.
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