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

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Presentation on theme: "Daniel Metcalfe Oxford University Centre for the Environment Comprehensive monitoring of carbon allocation and cycling across."— Presentation transcript:

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

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

3 Increasing CO 2 “fertilizer” in the atmosphere

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

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

6 Dry season length + - Current trends: spatial variation

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

8 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

9 Constructing bottom-up carbon budgets

10 Equipment contruction & installation

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

12 P canopy P stem M leaf M stem

13 Foliage density

14 Classification

15 Outputs

16 Specific leaf area

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

18 Leaf morphology

19 Variation with canopy height

20 Leaf dark respiration

21 Leaf light respiration

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

23 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

24 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

25 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

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

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

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

29 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.

30 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)

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

32 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

33 Caxiuana Tanguro Noel Kempff Andes Transect Iquitos

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

35 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

36 Robustness of the modelled “Amazon drought”

37 Short-term model predictions: Climate & Carbon

38 Differences amongst regions

39 Long-term model predictions: Vegetation

40 Long-term model predictions: vegetation

41 ↑ 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

42 Results from the first two years: soil moisture

43 Results from the first two years: canopy properties

44 Results from the fifth year: canopy properties

45 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

46 ↑ 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

47 Overlooked components of the C cycle Leaf dark respiration

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

49 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 ? ? ?

50 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

51 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.


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