Objetivo
THE AIM IS TO STUDY NUTRIENT CYCLING IN MIXED AND PURE SPRUCE STANDS IN EXISTING EXPERIMENTS (TWO IN UNITED KINGDOM, ONE IN IRELAND) IN ORDER :
- TO ELUCIDATE THE PROCESSES THAT ENABLE NITROGEN TO CYCLE MORE RAPIDILY IN MIXED SPRUCE-LARCH AND SPRUCE-PINE STANDS THAT IN PURE SPRUCE STANDS,
- TO IDENTIFY ANY DISTURBANCES TO NUTRIENT CYCLES AND TREE GROWTH THAT ARE ASCRIBABLE TO ACID RAIN.
THE CYCLE OF NUTRIENTS WILL BE FOLLOWED IN REPLICATED PLOTS OF MIXED AND PURE SPRUCE AT THE TWO U.K. LOCATIONS, IN PARALLEL WITH THE IRISH STUDY,WITH SUPPLEMENTARY MEASUREMENTS AT THREE FURTHER SITES IN SCOTLAND AND ONE IN IRELAND, SO ENSURING A WIDE RANGE OF GROWTH CONDITIONS AND EXPOSURE TO POLLUTANTS. INPUTS OF NUTRIENTS AND POLLUTANTS IN RAIN AND AEROSOLS WILL BE MEASURED WITH SPECIALLY DESIGNED RAIN GAUGES WHILST STEMFLOW GUTTERS AND THROUGHFALL TROUGHS WILL BE USED TO ASSESS TRANSFER BELOW THE CANOPY.
WHOLE TREE SAMPLING AND LITTER-FALL MEASUREMENTS ARE BEING USED TO DETERMINE RATE OF NITROGEN UPTAKE. PARTICULAR ATTENTION TO BE GIVEN TO THE RATE AND LOCATION OF NITROGEN MINERALIZATION IN RELATION TO THE DISTRIBUTION OF ROOTS IN THE DIFFERENT SPECIES COMBINATIONS. ROOTING PATTERNS ARE BEING EXAMINED BY CAREFUL EXCAVATION OF MAJOR ROOTS COUPLED WITH MEASUREMENTS OF FINE ROOT TURN-OVER BASED ON BOTH REGULAR SAMPLING OF SOIL CORES AND INGROWTH EXPERIMENTS. NITROGEN MINERALIZATION IS TO BE ASSESSED BY REPEATED SAMPLING FOR MEASUREMENT OF NH4+AND NO3-BEFORE AND AFTER LABORATORY INCUBATION, BY USE OF FIELD INCUBATIONS, BY INSTALLATION OF SUCTION LYSIMETERS AND BY THE INSERTION INTO THE SOIL OF A LARGE NUMBER OF BAGS OF MIXED ION-EXCHANGE RESINS. THIS ASPECT OF THE WORK IS CLOSELY LINKED TO EXAMINATIONS IN THE FIELD OF THE TYPES AND FORMS OF MYCORRHIZAL AND SAPROPHYTIC FUNGI PRESENT AND TO MEASUREMENTS OF TOTAL MICROBIAL BIOMASS, LEADING TO GREENHOUSE AND MICROCOSM EXPERIMENTS DESIGNED TO ISOLATE THE ROLE OF DIFFERENT FUNGAL AND OTHER MICROBIAL POPULATIONS IN THE NITROGEN CYCLE.
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AB15 8QH ABERDEEN
Reino Unido