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Driven By Nature: Plant Litter Quality and Decomposition
01 Nov 1996-
TL;DR: Pathways and processes in decomposition foraging, feeding and feedback manipulation of plant litter quality synchrony and soil organic matter - theory into practice?
Abstract: Pathways and processes in decomposition foraging, feeding and feedback manipulation of plant litter quality synchrony and soil organic matter - theory into practice? building soil organic matter modelling - providing the framework.
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TL;DR: The relationship between soil structure and the ability of soil to stabilize soil organic matter (SOM) is a key element in soil C dynamics that has either been overlooked or treated in a cursory fashion when developing SOM models as discussed by the authors.
Abstract: The relationship between soil structure and the ability of soil to stabilize soil organic matter (SOM) is a key element in soil C dynamics that has either been overlooked or treated in a cursory fashion when developing SOM models. The purpose of this paper is to review current knowledge of SOM dynamics within the framework of a newly proposed soil C saturation concept. Initially, we distinguish SOM that is protected against decomposition by various mechanisms from that which is not protected from decomposition. Methods of quantification and characteristics of three SOM pools defined as protected are discussed. Soil organic matter can be: (1) physically stabilized, or protected from decomposition, through microaggregation, or (2) intimate association with silt and clay particles, and (3) can be biochemically stabilized through the formation of recalcitrant SOM compounds. In addition to behavior of each SOM pool, we discuss implications of changes in land management on processes by which SOM compounds undergo protection and release. The characteristics and responses to changes in land use or land management are described for the light fraction (LF) and particulate organic matter (POM). We defined the LF and POM not occluded within microaggregates (53–250 μm sized aggregates as unprotected. Our conclusions are illustrated in a new conceptual SOM model that differs from most SOM models in that the model state variables are measurable SOM pools. We suggest that physicochemical characteristics inherent to soils define the maximum protective capacity of these pools, which limits increases in SOM (i.e. C sequestration) with increased organic residue inputs.
3,301 citations
TL;DR: In this paper, soil organic carbon (SOC), biota, ionic bridging, clay and carbonates are associated with aggregation by rearrangement, flocculation and cementation.
3,241 citations
National University of Cordoba1, SupAgro2, Joseph Fourier University3, University of Alaska Fairbanks4, VU University Amsterdam5, Kansas State University6, University of Western Australia7, University of Minnesota8, Wageningen University and Research Centre9, Macquarie University10, Stanford University11, Spanish National Research Council12, ETH Zurich13, University of Sheffield14, Utrecht University15, University of California, Los Angeles16, University of Arizona17, University of Regensburg18, Princeton University19, Centro Agronómico Tropical de Investigación y Enseñanza20
TL;DR: This new handbook has a better balance between whole-plant traits, leaf traits, root and stem traits and regenerative traits, and puts particular emphasis on traits important for predicting species’ effects on key ecosystem properties.
Abstract: Plant functional traits are the features (morphological, physiological, phenological) that represent ecological strategies and determine how plants respond to environmental factors, affect other trophic levels and influence ecosystem properties. Variation in plant functional traits, and trait syndromes, has proven useful for tackling many important ecological questions at a range of scales, giving rise to a demand for standardised ways to measure ecologically meaningful plant traits. This line of research has been among the most fruitful avenues for understanding ecological and evolutionary patterns and processes. It also has the potential both to build a predictive set of local, regional and global relationships between plants and environment and to quantify a wide range of natural and human-driven processes, including changes in biodiversity, the impacts of species invasions, alterations in biogeochemical processes and vegetation–atmosphere interactions. The importance of these topics dictates the urgent need for more and better data, and increases the value of standardised protocols for quantifying trait variation of different species, in particular for traits with power to predict plant- and ecosystem-level processes, and for traits that can be measured relatively easily. Updated and expanded from the widely used previous version, this handbook retains the focus on clearly presented, widely applicable, step-by-step recipes, with a minimum of text on theory, and not only includes updated methods for the traits previously covered, but also introduces many new protocols for further traits. This new handbook has a better balance between whole-plant traits, leaf traits, root and stem traits and regenerative traits, and puts particular emphasis on traits important for predicting species’ effects on key ecosystem properties. We hope this new handbook becomes a standard companion in local and global efforts to learn about the responses and impacts of different plant species with respect to environmental changes in the present, past and future.
2,744 citations
Cites background from "Driven By Nature: Plant Litter Qual..."
...References on theory, significance and large datasets: Cain (1950); Ellenberg and Müller-Dombois (1967); Whittaker (1975); Barkman (1988, and references therein); Rundel (1991); Richter (1992); Box (1996); Ewel and Bigelow (1996); Cramer (1997); Lüttge (1997); Medina (1999); McIntyre and Lavorel (2001)....
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TL;DR: This review examines how variation in the relative availability of N and P, as reflected by N : P ratios of plant biomass, influences vegetation composition and functioning.
Abstract: Contents
Summary
I Introduction
II Variability of N : P ratios in response to nutrient supply
III Critical N : P ratios as indicators of nutrient limitation
IV Interspecific variation in N : P ratios
V Vegetation properties in relation to N : P ratios
VI Implications of N : P ratios for human impacts on ecosystems
VII Conclusions
Acknowledgements
References
Summary
Nitrogen (N) and phosphorus (P) availability limit plant growth in most terrestrial ecosystems. This review examines how variation in the relative availability of N and P, as reflected by N : P ratios of plant biomass, influences vegetation composition and functioning. Plastic responses of plants to N and P supply cause up to 50-fold variation in biomass N : P ratios, associated with differences in root allocation, nutrient uptake, biomass turnover and reproductive output. Optimal N : P ratios – those of plants whose growth is equally limited by N and P – depend on species, growth rate, plant age and plant parts. At vegetation level, N : P ratios 20 often (not always) correspond to N- and P-limited biomass production, as shown by short-term fertilization experiments; however long-term effects of fertilization or effects on individual species can be different. N : P ratios are on average higher in graminoids than in forbs, and in stress-tolerant species compared with ruderals; they correlate negatively with the maximal relative growth rates of species and with their N-indicator values. At vegetation level, N : P ratios often correlate negatively with biomass production; high N : P ratios promote graminoids and stress tolerators relative to other species, whereas relationships with species richness are not consistent. N : P ratios are influenced by global change, increased atmospheric N deposition, and conservation managment.
1,836 citations
TL;DR: In this paper, an overview is given on the amount of litter input, the proportion of various plant parts and their distribution (below-ground/above-ground), as well as the relative proportion of different plant tissues.
Abstract: Plant litter and the microbial biomass are the major parent materials for soil organic matter (SOM) formation Plant litter is composed of complex mixtures of organic components, mainly polysaccharides and lignin, but also aliphatic biopolymers and tannins The composition and relative abundance of these components vary widely among plant species and tissue type Whereas some components, such as lignin, are exclusively found in plant residues, specific products are formed by microorganisms, eg amino sugars A wide variety of chemical methods is available for characterizing the chemical composition of these materials, especially the chemolytic methods, which determine individual degradation products and solid-state 13C NMR spectroscopy, that gives an overview of the total organic chemical composition of the litter material With the development of these techniques, an increasing number of studies are being carried out to investigate the changes during decay and the formation of humic substances An overview is given on the amount of litter input, the proportion of various plant parts and their distribution (below-ground/above-ground), as well as the relative proportion of the different plant tissues Major emphasis is on the organic chemical composition of the parent material for SOM formation and thus this paper provides information that will help to identify the changes occurring during biodegradation of plant litter in soils
1,547 citations