Daniel Metcalfe Oxford University Centre for the Environment Comprehensive monitoring of carbon allocation and cycling across the Amazon basin

Objectives 1) 1)Establish baseline of current forest carbon storage and allocation 2) 2)Monitor ongoing changes in forest carbon cycling

Increasing CO 2 “fertilizer” in the atmosphere

SENSITIVITY: TEMPERATURE Malhi and Wright (2004), Philosophical Transactions of the Royal Society

↓ precipitation↑ atmospheric CO 2 levels ↓ photosynthesis & ↑ soil respiration ↑ temperature ↑ terrestrial CO 2 emissions ↑ replacement of forest with savannah IPPC 2007 working group 1 report

Dry season length + - Current trends: spatial variation

Field Sites Caxiuana Tanguro Noel Kempff Kosnipata Iquitos Tambopata Comparisons Drought Soil type Fire Altitude

Ecosystem respirationNet primary production R stem R leaf R soil P canopy P stem P root R cwd M leaf M root M stem Constructing bottom-up carbon budgets R soil R roots R mycorrhizae R som R litter Soil CO 2 efflux partitioning

Constructing bottom-up carbon budgets

Equipment contruction & installation

Ecosystem respirationNet primary production R stem R leaf R soil P canopy P stem P root R cwd M leaf M root M stem

P canopy P stem M leaf M stem

Foliage density

Classification

Outputs

Specific leaf area

Threshold image to calculate area Fill in eaten leaf area to quantify herbivory

Leaf morphology

Variation with canopy height

Leaf dark respiration

Leaf light respiration

Ecosystem respirationNet primary production R stem R leaf R soil P canopy P stem P root R cwd M leaf M root M stem

Stem Dynamics Measurements 1)Below and above 10cm DBH 2) Basic data (species, DBH, height wood density) 3) Mode of death 4) Respiration......basal vs contruction respiration Respiration Growth

Biomass change / Mg ha -1 yr No. plots 1.22 ± 0.42 Mg ha -1 yr -1 Histogram of rate of biomass change over the 1980s and 1990s as observed in 59 RAINFOR plots. The mean change is 1.22±0.42 Mg biomass ha -1 year -1. From Baker et al (2004), Philosophical Transactions of the Royal Society of London. Current trends: Increasing biomass

Changes in tree recruitment (green) and mortality as observed in RAINFOR old-growth forest plots in recent decades. Forests appear to be becoming Increasingly dynamic. From Phillips et al (2004) Annual rate of stem mortality/recruitment (%) Year Current trends: Increasing dynamism

Ecosystem respirationNet primary production R stem R leaf R soil P canopy P stem P root R cwd M leaf M root M stem

Ecosystem respirationNet primary production R stem R leaf R soil P canopy P stem P root R cwd M leaf M root M stem

TECHNIQUES: RHIZOTRONS 1.In situ measurement 2.High temporal frequency 3.Record root growth, mortality, longevity

RHIZOTRONS: CONVERTING LENGTH TO MASS  Calculate cross-sectional root area  Multiply area by length/width of plot to derive volume  Multiply volume by root density Frequent root mass production (t ha-1) rhizotron screen roots Source: Bernier & Robitaille. (2004), Plant and Soil.

TECHNIQUES: INFRA-RED GAS ANALYZER CO 2 IRGA 1.Record soil respiration 2.Remove litter, measure respiration again 3.Remove soil core, roots from core. Measure root respiration. 4.Subtract root and litter respiration from total soil respiration isolate litter contribution estimate root contribution estimate residual respiration (i.e.: from soil organic matter)

Soil CO 2 efflux partitioning No litter Control2 × litter Control No roots or mycorrhizae No roots

Key websites - -The Amazon Forest Inventory Network: - -Project for the Advancement of Networked Science in Amazonia: Large Scale Atmosphere-Biosphere Experiment in Amazonia: Daniel Metcalfe

Caxiuana Tanguro Noel Kempff Andes Transect Iquitos

Lloyd (1999), Functional Ecology. The effect of CO 2 fertilizer on terrestrial ecosystems The current effect of CO 2 fertilizer on terrestrial ecosystems

Synthesis of results 1.Good evidence for drought-induced decline in photosynthesis, this is balanced out by a decline in soil CO 2 efflux. 1.Good evidence for drought-induced decline in photosynthesis, but this is balanced out by a decline in soil CO 2 efflux. What accounts for inter-annual patterns? 2.Some evidence for drought-induced changes in mortality and reproduction, massive variability. 2.Some evidence for drought-induced changes in mortality and reproduction, but massive variability. 3.Overall, the forest appeared suprisingly resilient to drought BUT Other poorly quantified components of the carbon cycle

Robustness of the modelled “Amazon drought”

Short-term model predictions: Climate & Carbon

Differences amongst regions

Long-term model predictions: Vegetation

Long-term model predictions: vegetation

↑ atmospheric CO 2 levels ↓ precipitation ↓ photosynthesis & ↑ soil respiration ↑ temperature ↑ terrestrial CO 2 emissions e.g.: see Cox et al. (2000), Nature. ↑ replacement of forest with savannah

Results from the first two years: soil moisture

Results from the first two years: canopy properties

Results from the fifth year: canopy properties

Results: tree dynamics Mortality over 3 years Control: 2.4% of pop. TFE: 1.5% of pop. BUT Control: 1.3 t C ha -1 TFE: 2.1 t C ha -1

↑ atmospheric CO 2 levels ↓ precipitation ↓ photosynthesis & ↑ soil respiration ↑ temperature ↑ terrestrial CO 2 emissions e.g.: see Cox et al. (2000), Nature. ↑ replacement of forest with savannah

Overlooked components of the C cycle Leaf dark respiration

TEMPORAL TRENDS: RESPIRATION Model uncertainty caused mainly by lack of information about below-ground processes Source: Lloyd & Prentice (1998), Nature.

RHIZOTRONS: RESULTS surge in both growth and mortality during the wet season Additional surge on the Drought plot coinciding with the first big rain events ? ? ?

SYNTHESIS: ABOVE- & BELOW-GROUND DATA Treatment differences in stem wood production are relatively small compared to root and litter fall production The drought treatment alters ecosystem carbon cycling, e.g.: the balance between carbon entering the soil via litter fall, and leaving via microbial respiration

Accounts for 45% of the worlds tropical forest Stores 40% of carbon residing in terrestrial vegetation Hosts a large proportion of global biodiversity Malhi & Grace (2000), TREE.