Phosphorus cycling in fast growing forest plantations: availability, plant uptake and the role of forest floor

dc.contributor
Universitat de Barcelona. Departament de Biologia Vegetal
dc.contributor.author
Romanyà i Socoró, Joan
dc.date.accessioned
2011-04-12T13:22:16Z
dc.date.available
2010-02-01
dc.date.issued
1993-02-25
dc.date.submitted
2010-02-01
dc.identifier.isbn
9788469305461
dc.identifier.uri
http://www.tdx.cat/TDX-0201110-114543
dc.identifier.uri
http://hdl.handle.net/10803/957
dc.description.abstract
The research reported in this thesis focuses on studying the effects of naturally occurring mycorrhiza and the role of forest floor in the cycling of P in fast growing forest plantations. In order to study the effects of mycorrhizae on forest soils fertility and the subsequent seedling growth response, radiata pine (Pinus radiata D. Don) seedlings were grown in pots using the soil collected from a mature (23 year old) radiata pine plantation. The experiment was arranged in a two factor design. The treatments comprised of sterilized and unsterilized soil, either fertilized with superphosphate (100 KgP/ha) or remained non-fertilized. In an attempt to explore nutrient uptake mechanisms under contrasted soil fertility and under mycorrhizal and non-mycorrhizal conditions, Barber-Cushman nutrient uptake model was used to simulate nutrient uptake in these treatments.<br/><br/>Mycorrhiza suppressed treatments showed low mineral NO3-N concentration and high autoclave N in soil. NH,-N concentration was not affected by any treatment. Water and bicarbonate soluble reactive P (SRP) and soluble non-reactive P (NRP) were not changed by mycorrhiza. Phosphatase activity greatly decreased in mycorrhiza suppressed treatments. Despite superphosphate addition increased all forms of P, acid phosphatase activity did not change by this factor.<br/><br/>Mycorrhiza suppression decreased seedling growth but not root length or surface. Non-mycorrhizal seedlings showed a much large proportion of roots thinner than 0.5 mm diameter. While in 7 month old seedling needle development was delayed in nonmycorrhizal pots, 4 months later all needles had the same size. At this stage of growth, plant adapted to nutritional shortages by loosing needles. Except in non-mycorrhizal-unfertilized seedlings, where growth was limited by P, in the other treatments growth was N and Mg limited. Mycorrhizal associations increased the specific uptake rate (mmol cm(-1) root) for N, P, K, S, Mg, Ca and Al. While under natural P availability conditions, P uptake was largely reduced after mycorrhiza suppression, under high P availability it was hardly increased by mycorrhiza. Barber-Cushman model was able to predict the relative variations in P and Mg uptake only in non-mycorrhizal treatments. While P uptake appeared to be controlled by root surface, Mg uptake was mostly regulated by root length.<br/><br/>To study the role of the forest floor in the cycling of nutrients, nutrient leaching through litter layers was monitored in a mature radiata pine plantation (18 year old) using 20 zerotension lysimeters installed underneath the Oa horizon.<br/><br/>Both P and N concentrations in the litter leachates showed large seasonal changes. Organic P compounds were more readily retained at the forest floor than organic N compounds. A large proportion of nutrients leached throughout the year (51% and 61% of total P and N exported respectively) took place during short periods of time. Most N transferred from the forest floor to the mineral soil was in organic form. In contrast, P was mostly transferred as inorganic P (SRP). The total amount of nutrient exported to the mineral soil were of the same order of magnitude than the yearly nutrient increases in aboveground biomass. There were evidences suggesting that a major content part of this nutrient flow originated in the forest canopy.<br/><br/>Using a new proposed anion resin fractionation technique, P forms in litter leachates and soil solution were compared. This technique showed that Murphy and Riley method to determine P concentration in solution was not able to distinguish clearly between inorganic and organic P in solution. One limitation of the fractionation technique was that it was not a clean separation of organic and inorganic P forms. However, it does appear to be useful for documenting relative changes in P forms when samples are contrasted.<br/><br/>In a mixed Eucalyptus forest in SE Australia, the effect of slash burning on surface soil P forms and on sorption and desortption of P were studied. According to fire intensity, three different microsites were selected: unburnt , burnt and intensely burnt.<br/><br/>The effects of fire on soil P were greatest in the surface soil horizons and depended upon fire intensity. After fire labile inorganic P (Bray I) increased from <1 mg kg(-1) to 5-13 mg kg(-1) in the ash bed. The increase in labile organic P (NaHCO2) contrasted with a decrease in total organic P (H2SO4) and less labile organic P (NaOH) in ashbed soils. The ashbed soil showed an increase insorption capacity in the 0-5 cm layer, but the sorbed P was generally less tightly bound to the solid phase.
eng
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
Universitat de Barcelona
dc.rights.license
ADVERTIMENT. L'accés als continguts d'aquesta tesi doctoral i la seva utilització ha de respectar els drets de la persona autora. Pot ser utilitzada per a consulta o estudi personal, així com en activitats o materials d'investigació i docència en els termes establerts a l'art. 32 del Text Refós de la Llei de Propietat Intel·lectual (RDL 1/1996). Per altres utilitzacions es requereix l'autorització prèvia i expressa de la persona autora. En qualsevol cas, en la utilització dels seus continguts caldrà indicar de forma clara el nom i cognoms de la persona autora i el títol de la tesi doctoral. No s'autoritza la seva reproducció o altres formes d'explotació efectuades amb finalitats de lucre ni la seva comunicació pública des d'un lloc aliè al servei TDX. Tampoc s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing). Aquesta reserva de drets afecta tant als continguts de la tesi com als seus resums i índexs.
dc.source
TDX (Tesis Doctorals en Xarxa)
dc.subject
Nutrició vegetal
dc.subject
Arrels (Botànica)
dc.subject
Sòls forestals
dc.subject.other
Ciències Experimentals i Matemàtiques
dc.title
Phosphorus cycling in fast growing forest plantations: availability, plant uptake and the role of forest floor
dc.type
info:eu-repo/semantics/doctoralThesis
dc.type
info:eu-repo/semantics/publishedVersion
dc.subject.udc
58
cat
dc.contributor.authoremail
jromanya@ub.edu
dc.contributor.director
Vallejo, V. Ramón (Victoriano Ramón)
dc.rights.accessLevel
info:eu-repo/semantics/openAccess
dc.identifier.dl
B.14664-2010


Documents

01.JRS_1de1.pdf

8.614Mb PDF

This item appears in the following Collection(s)