Introduction.- Decomposition as a process.- Decomposer organisms.- Initial litter chemical composition.- Changes in substrate composition during decomposition.- Chemical constituents as rate-regulating: initial variation and changes during decomposition.- Climatic environment.- Influence of soil and plant community factors.- Decomposition of fine root and woody litter.- Models that describe litter decomposition.- Decomposition and ecosystem function.- Human activities that influence decomposition.- Estimating carbon sequestration rates on a regional scale.- Appendix I. Glossary.- Appendix II. Scientific names of vascular plants.- Appendix III. Site descriptions.- Appendix IV. A data base for litter chemical composition, and limit values for decomposition - Delila.-

Plant Litter: Decomposition, Humus Formation, Carbon Sequestration

Although it is generally acknowledged that invasions by exotic plant species represent a major threat to biodiversity and ecosystem stability, little attention has been paid to the potential impacts of these invasions on nutrient cycling processes in the soil. The literature on plant–soil interactions strongly suggests that the introduction of a new plant species, such as an invasive exotic, has the potential to change many components of the carbon (C), nitrogen (N), water, and other cycles of an ecosystem. I have reviewed studies that compare pool sizes and flux rates of the major nutrient cycles in invaded and noninvaded systems for invasions of 56 species. The available data suggest that invasive plant species frequently increase biomass and net primary production, increase N availability, alter N fixation rates, and produce litter with higher decomposition rates than co-occurring natives. However, the opposite patterns also occur, and patterns of difference between exotics and native species show no trends in some other components of nutrient cycles (for example, the size of soil pools of C and N). In some cases, a given species has different effects at different sites, suggesting that the composition of the invaded community and/or environmental factors such as soil type may determine the direction and magnitude of ecosystem-level impacts. Exotic plants alter soil nutrient dynamics by differing from native species in biomass and productivity, tissue chemistry, plant morphology, and phenology. Future research is needed to (a) experimentally test the patterns suggested by this data set; (b) examine fluxes and pools for which few data are available, including whole-site budgets; and (c) determine the magnitude of the difference in plant characteristics and in plant dominance within a community that is needed to alter ecosystem processes. Such research should be an integral component of the evaluation of the impacts of invasive species.

Effects of Exotic Plant Invasions on Soil Nutrient Cycling Processes

How strongly can forest management influence soil carbon sequestration

More than 6500 species of Collembola are known from throughout the world and these are only a small part of the still undescribed species. There are many checklists and catalogues of Collembola for smaller territories and entire continents. Biogeographical analyses have been made for some genera and smaller territories. The most serious problems for a global biogeographical analysis is the lack of enough records from immense territories of all continents. Local biodiversity of Collembola can be very high, reaching over 100 species in small mountain ranges. Sampling methods do not impede documenting biodiversity on a global scale. Collembola have well differentiated ecomorphological life-forms and feeding guilds which enable the functional role that Collembola play in ecosystems to be recognised in some degree. Collembola play an important role in plant litter decomposition processes and in forming soil microstructure. They are hosts of many parasitic Protozoa, Nematoda, Trematoda and pathogenic bacteria and in turn are attacked by different predators. They utilise as food Protozoa, Nematoda, Rotatoria, Enchytraeidae, invertebrate carrion, bacteria, fungi, algae, plant litter, live plant tissues, and some plant pathogens. Soil acidification, nitrogen supply, global climate change and intensive farming have greatly impacted collembolan diversity.

Biodiversity of Collembola and their functional role in the ecosystem

/pdf/retention-or-loss-of-n-in-ifs-sites-and-evaluation-of-s9c2r7l2iu.pdf

Retention or Loss of N in IFS Sites and Evaluation of Relative Importance of Processes

Soil animals were allowed to colonise sterile soil samples from three soil types: raw humus, poor mull and rich mull. Within each soil type, samples adjusted to three different pH levels were offered. Soil pH significantly influenced the success of colonisation in the following number of species: Collembola 7, Oribatei 8 (minimum), Mesostigmata 3, Astigmata 1, Enchytraeidae 3, and Lumbricidae 1. In all three soils, there were reactions both in favour of acidification and of liming. The largest number of species reacting to the treatments was found in raw humus, where the most marked pH gradient occurred. When a species reacted to both lowered and raised soil pH, these reactions were always opposite. Within the same species, reaction patterns in different soil types supported each other. High numbers of Acari in acidified raw humus was mainly due to Tectocepheus velatus Michael, Nothrus silvestris Nicolet and Schwiebea cf. nova (Oudemans). Age structure indicated that soil pH influenced reproductive success. For several species, reactions were supported by current field experiments and information on the species' natural occurrence.

Colonisation by Enchytraeidae, Collembola and Acari in sterile soil samples with adjusted pH levels

The microarthropod and enchytraeid fauna of a natural lead-contaminated soil in a Norwegian spruce, Picea abies (L.) Karst., forest was studied in gradients from unpolluted soil to the middle of a vegetation-free area. Because of dissolved lead from the bedrock, about 50 m2 of the forest floor lacked vegetation, and another 50 m2 had weakly developed vegetation. The lead content in the raw humus was up to 10–15% dry wt. Increasing levels of lead gave a gradual reduction in species numbers among plants and microarthropods. Microarthropod species varied in their ability to live in lead-polluted soil. Four groups were recognized: (1) sensitive species associated with normal vegetation, (2) less sensitive species occurring even in areas with strongly reduced vegetation, (3) tolerant species extending their range into vegetation-free areas, and (4) microarthropods favored by strong lead pollution ( Isotoma olivacea Tullberg among Collembola and Nanorchestes sp. among mites). Because a few species increased strongly in the vegetation-free area, the total abundance of microarthropods remained almost the same throughout the gradient. Changes in vegetation cover along the lead gradient is a confounding factor, but sensitive species proved to react equally negatively to increased lead levels when the vegetation factor was kept constant. Possible adaptations to lead during the postglacial period are discussed.

Microarthropoda and Enchytraeidae (Oligochaeta) in Naturally Lead-Contaminated Soil: A Gradient Study

Litter decomposition is an important part of nutrient cycling in natural ecosystems. A major part of the nutrients taken up by the vegetation is returned to the soil through litter fall. Decomposition begins when living tissue dies, even if it is still attached to the plant. In the boreal forest, decomposition is often slow and an accumulation of organic matter on the soil is common. This layer is inhabited by enormous numbers of soil organisms: fungi, bacteria and invertebrate animals. These organisms take part in the decomposition of organic matter; as the nutrients are moving within complicated food webs the importance of these various organisms is hard to predict.

Effects of Artificial Acid Rain and Liming on Soil Organisms and the Decomposition of Organic Matter

Scots pine and Norway spruce stands responses to annual N, P and Mg fertilization

Dry matter and chemical changes in decomposing spruce needles were investigated after 16 and 38 weeks in laboratory lysimeters treated with distilled water or distilled water acidified to pH 3 or 2 with sulphuric acid. The water was added twice weekly in quantities equal to 100 or 200 mm month−1. The CO2 evolution and leaching of P, K, Mg, Mn, and Ca was followed together with pH measurements of the leachate. The loss of dry matter was approximately 25% during the first 16 weeks and approximately 37% after 38 weeks. At the first samling, 16 weeks, the amount of material decomposed was greater from the lysimeters given 100 mm month−1 of water. At this water quantity dilute sulphuric acid increased the decomposition. After 38 weeks sulphuric acid at pH 3 and 2 had decreased the decomposition at 200 mm month−1. However, the effects of acid application were small. The effect of treatment using acidified water on the content of monosaccharides was not consistent, whereas there was an indication of reduced decomposition of lignin when treated with 200 mm water month−1 at pH 3 and 2. Nitrogen was conserved in the lysimeters with small differences between the various treatments. The order of mobility of metal elements was K>Mg>Mn>Ca. Increasing the quantity of water increased the leaching of K especially, whereas addition of dilute sulphuric acid increased the leaching of Mg, Mn and particularly Ca. During the first 16 weeks of the experiment, sulphuric acid reduced the leaching of P while later on this treatment increased the leaching. The pH of the leachate from the lysimeters treated with distilled water was initially 4.0–4.6 increasing to approximately 6.6 after 22 weeks. The pH of the decomposed needle material was 4.6 and approximately 5.2 after 16 and 38 weeks respectively. When treated with water at pH 3 the pH of the leachate was between 4 and 5, and the pH of the needles 4.2–5.1. Treatment with water at pH 2 gave a leachate with pH just above 2 and decreased the pH of the needles that had received 200 mm ‘rain’ month−1 to 2.9. The effect of the artificial acid rain appears to be more pronounced on the leaching of metal elements than on the biological activity and the dynamics of N and P. The treatments must be considered extreme when compared with the acidity of natural rain.

Effects of artificial acid rain on decomposition of spruce needles and on mobilisation and leaching of elements.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Gunnar Abrahamsen

Author Tools

Chat about Author