academic forestry education in estonia...compounds. c is the scelet of organic substances....
TRANSCRIPT
Forest biogeochemistry
Kalev Jõgiste
In Earth science, a biogeochemical cycle or
substance turnover or cycling of substances is a
pathway by which a chemical substance moves
through both biotic (biosphere) and abiotic
(lithosphere, atmosphere, and hydrosphere)
compartments of Earth.
HUMAN SENSES
• Sight (ophthalmoception), hearing
(audioception), taste (gustaoception), smell
(olfacoception or olfacception), and touch
(tactioception) are the five traditionally
recognized. They help us to recognize the
existence of trees, animals, fish etc. We do
neeed to recognize the process of energy
accumulation at different trophic levels.
• (Kimmins 1997:71).
• Energy enters the ecosystem „goes „ through it and
at the end disappears from the ecosystem
• Chemical substances and compounds which circulate
along with energy flows (they are bound to energy
transfers) are re-used and circulated in the
ecosystem
CYCLES
• 1. Geochemical cycle: transfer and movement of
chemical substances between ecosystems
• 2. Biogeoschemical cycle: movement of chemical
substances within the ecosystem
• 3. Biochemical cycle: transfer and relocation of
chemical components within the organism and between
living organisms
• 96% of plant try biomass consists of atoms of H, O, C N
• MINERAL NUTRIENTS
• Macroelements (H, C, O, N, Ca, K, Mg, P ja S)
• Microelements (B, Cl, Mn, Fe, Cu, Zn, Mo, Ni ja V
micro-organisms)
CLASSIFICATION
• 3. Group (K+, Ca++, Mg++) – Mineral nutrient
essential in many physiological processes including
osmosis regulation , the opening and closing of
stomata (K), photosynthetic transport (K), membran
permeation (Ca), photosynthesis (Mg). K and Mg –
important components of enzymes. The elemets of
this group are bound to ecosystem circulation and
soil
• Enzymes are macromolecular biological catalysts.
They are responsible for thousands of metabolic
processes that sustain life. Enzymes are highly
selective catalysts, greatly accelerating both the rate
and specificity of metabolic reactions, from the
digestion of food to the synthesis of DNA.
• 1. Group (C, H, O) – the components of organic
compounds. C is the scelet of organic substances.
• Carbohydrates: sugar, starch, cellulose, fatty acids,
lipids, phenolic compounds . Those elements are
found in global cycle
• 2. Group (N, S, P) – mineral nutrients which are
bounded with covalent bonds to C (N, S) or O (P and
S). Important components of proteins (N and S);
nucleid accids
• mineraaltoiteained, mis on tugevate kovalentsete
sidemetega ühendatud C-ga (N ja S) või O-ga (P ja
S). Tähtsad proteiinides (N ja S); nukleiinhapetes (N
ja P); aminohapped proteiini tarbeks; ATP-ADP
kompleks. Tugevalt seotud mulla orgaanilise ainega
ja väga tugevast haaratud ringesse.
Microelements
• Group 4. (Fe, Mn, Co, Zn, Mo ja B) – all microelements (except B ) are
important component of enzymes. Fe is important cytochrome and
ferredoxin,
• which are important in electron transport during photosythesis. Many
physiological processes require microelements as activator or mediators.
These elements are bounded to chelate complexes (humus, fulvic acids).
• Geochemic cycle: the input of nutrient to ecosystem
and output
• Is it cycle???
Geochemical cycle - developmental path followed by individual
elements or groups of elements in the crustal and subcrustal zones
of the Earth and on its surface. The concept of a geochemical
cycle encompasses geochemical differentiation (i.e., the natural
separation and concentration of elements by Earth processes) and
heat-assisted, elemental recombination processes.
• C, H, O, N, and S: all those elements enter the
ecosystems or can leave that in gaseous compounds
(but also as vapor, dust or soluble components)
• C, O, N – gaseous intake is main way
Gaseous way
• CO2 – green plants are absorbing from air
• N2 – fixation by microorganisms
• NB! NH3 (ammoniac) the intake by leave from air
can reach 10% of all amount
• N is also in minerals, O is chemically bound, C –
small amount in minerals
• SO2 – small amount is absorbed by leaves
+ (intake)
• SO2 – emitted from leaves and also leaching out
with soluble compounds
• CO2 – emitted with respiration
- output
• All chemical compounds which are mineral
nutrients are moving in sedimentary cycle
• Subdivision: Meteorological cycle
• Intake is realized as dust, aerosol, precipitation
• Output is realized by wind or water erosion
•SEDIMENTARY
• N – Nitrate (NO3-) ja ammonium (NH4+) ion can
enter the ecosystem as wet or dry precipitation
• K, Ca, S, can enter the ecosystem as wet or dry
precipitation
• (P, less than other macro-elements)
+ intake
Nitrate
• Animals: the movement (migration) of animals and
migration of chemical compounds is balanced with
intake and output
BIOLOGICAL MECHANISM
•+ • 1. Weathering and chmeical weathering of rocks
and soil mineral part and release of nutrients.
• 2. Nutrients, compounds that are soluble in water,
and the flow of water entering the soil ecosystem.
•- • Nutrients that have solutions for both soil water and
surface water outflow. Water erosion of organic and
mineral material.
GEOLOGICAL /HYDROLOGICAL
• BIOGEOCHEMICAL CYCLE MEANS THE
CONSTANT MOVING (EXCHANGE) OF
CHEMICAL ELEMETS WITHIN ECOSYSTEM
BETWEEN LIVING AND NONLIVING
COMPONENTS
• 1. Soluble components with water
• 2. Physiological processes
• 2. Mycotrophic
Nutrient uptake
• 1. Leaching with rainwater
• 2. Biomass eaten (consumed) by herbivores
• 3. Reproduction costs
• 4. Litter and mortality
• 5. Litter decomposition
Allocation of nutrients in plants and vegetation:
Movement and exchange in biogeochemical cycle
• LITTER: FALLING DURING ONE YEAR
• LITTER ACCUMULATION
•Mechanism of biogeochemical cycle
Movement of nutrients in plants:
Biochemistry
• Biochemical cycle
• Plant physiology
Proportion % Carbon N H O
Lipids 75-78 - 8-11 9-17
Sugar, starch 40 - 7 52
Hemicellulose,
cellulose
43 - 7 49
Lignin 67 - 6 27
Protein 40-50 10-25 5-10 22-40
The nutrient cycle occupies a key position in ecosystem processes.
Primary production is regulated in large part by the rate at which
nutrients are cycled, and the ability of the system both to store
nutrients and to regulate their release provides stability against
environmental fluctuations and facilitates recovery from
disturbance.
Different plant species and guilds may regulate nutrient cycling in
such a way as to facilitate their own persistence in a community,
thereby creating a self-reinforcing, positive feedback loop between
ecosystem structure and processes.
Nutrient Fluxes in Local Ecosystems
Intraystem Nutrient Cycle
Soil water is the conveyer belt that distributes soluble nutrients
throughout the soil matrix.
Nutrients are exchanged between the soil solution and several
reservoirs.
Plants both take up and release nutrients to solution, and
nutrients in litter and humus are incorporated into the bodies of
microbes and soil animals and eventually released into the soil
solution (where they are available for uptake once again).
Nutrients are exchanged between solution and electrical charges
on the surfaces of clays and organic matter.
Intraystem Nutrient Cycle
Some nutrients, such as iron, from insoluble combinations and
precipitate out of solution, entering again very slowly.
Nutrients may enter soil solution directly from the atmosphere,
and some are released again into the atmosphere as gases.
A few are leached from the local ecosystem to streams, but such
nutrient loss is relatively minor in undisturbed forests.
Components of the Intrasystem Cycle
Intraystem Nutrient Cycle
Any breakdown of ecosystem components is artificial to one
degree or another, we consider the following compartments:
Aboverground plant tissues, along with associated epiphytes and
microbes.
Animals that graze aboveground tissues.
Belowground plant tissues and plant mutualists, including roots,
mycorrhizae, mycorrhizal hyphae, and obligate rhizosphere
bacteria.
Intraystem Nutrient Cycle
Detritus, which is any organic matter that is not contained within
living body or cell or is not incorporated into humus or
organomineral complexes.
There are two distinct forms:
• Litter
• Exudates
A large proportion of detritus derives from plant litter (for
example: leaves, branches, roots, mycorrhizae); litter also includes
dead consumers (for example: microbes, protozoa, invertebrates,
vertebrates and both invertebrate and vertebrate feces.
Exudates are organic compounds that are released into the soil by
roots, mycorrhizae, micorrhizal hyphae, and microbes. A wide
variety of compounds are exuded from living cells, including
simple sugars, organic acids, and enzymes.
Belowground vs. Aboveground Litter – most studies have
focused on aboveground litter (litterfall). However, the few data
that is available suggest that in most forest ecosystems, the death
of roots and mycorrhizae account for two thirds or more of
nitrogen returned to the soil in plant litter.
Aboveground and Belowground Litter
Components of Litterfall in Three
Forest Types: An Example
Nutrient transfers also occur within as well as among
compartments. Trees withdraw nutrients from aging and dead
tissues, and use these to support new growth (for example:
internal cycling). Invertebrates recycle nutrients by eating their
own feces (coprophagy). Decomposers decompose other
decomposers, and grazers feed on other grazers. In general,
belowground food chains are longer and more complex than those
aboveground.
Transfers Among the Various
Compartments
Nitrogen fluxes in a old-growth Douglas-fir
forest in Oregon. Amount of nitrogen input
to this forest in precipitation is quite small,
and roughly equivalent to that leached from
the system.
Nutrient Cycling
The greatest proportion of forests yearly nutrient requirement is
satisfied by elements that are cycled both externally (for example:
in litter) and internally (for example: within the tree).
The relationship between tree uptake (upper line) and release of
nutrients in decomposition (lower line, shaded portion) for an age
sequence of Scots pine plantation in Great Britain. Stands vary
(because of site factors or management practices), but in most cases,
at least 50% of yearly uptake is matched by decomposition.