Fine root research methods Biomass:

Size: px

Start display at page:

Download "Fine root research methods Biomass:"

Evan Armstrong
7 years ago
Views:

1 Fine root production and turnover & carbon dynamics methodological considerations Heljä-Sisko Helmisaari Finnish Forest Research Institute Fine root research methods Biomass: - variation (site type, depthwise, seasonal) Biomass production & turnover rate

2 Carbon stores and fluxes in forests Deposition NPP Vegetation above- and belowground Harvesting Throughfall Litter production Litter above- and belowground Harvesting residue id CO 2, respiration Decomposition Soil organic matter Soil respiration CH 4 prod. Leaching, DOC From litter, carbon is either emitted as CO 2, immobilised in the structure of decomposing organisms, or accumulates into physically and chemically more or less stable structures

3 Field method development Morphology, architecture, biomass, necromass: digging, monoliths, soil cores Biomass production, mortality, turnover (production/biomass), longevity: windows, (mini)rhizotrones, ingrowth cores, radioisotopes Decomposition, respiration: litter bags, root/soil respiration chambers, trenching Mycorrhizal communities, species diversity: molecular methods

4 Field methods: soil cores actual and unaltered fine and small root biomass and necromass at stand level, spatial variation (depthwise and horizontally) temporal variation biomass production & turnover rate may be estimated by repeated samplings but necromass estimation less accurate > error increases

5 Field methods: ingrowth cores biomass production, mortality, turnover rate (production / biomass) comparison of production / turnover rate in different sites & stands effects of different experimental treatments temporal variation

6 Field methods: ingrowth cores Ingrowth cores Placing into soil in summer Early summer Late summer Summer 1. year 2. year 2. year 3. year Picture by Jarmo Karvonen.

7 Field methods: minirhizotrones Installing minirhizotrone tubes at Kivalo, northern Finland in 2003.

8 Field methods: minirhizotrones - fine root elongation = length production (can be converted into biomass), mortality, turnover, longevity

9 Sorting & analysis of roots A sorting station in Salla in Lapland: no losses of finest roots! root dry weights: - different tree species, grasses and shrubs - living and dead - diameter classes < 1mm, 1-2 mm = fine roots, 2-5 mm); experimentally also tighter classes (0-0.5, etc.) numbers of mycorrhizal root tips on finest roots (living < 1 mm diameter) / root weight unit ectomycorrhiza parameters: cooperation with Krista Lohmus and Ivika Ostonen Analyses at Metla Central Lab.: C & N concentrations other nutrients and organic compounds in part of the samples (lignin, cellulose etc.)

10 Scots pine fine roots with ectomycorrhiza root tips 1 mm Hyphae Yellow mycorrh.

11 Field method development All methods have their strengths and weaknesses: use of parallel methods is a strength. Choice of methods depends on study aims (and site characteristics). Most of the root study methods are tedious and time-consuming. Regardless of method, large spatial and temporal variation in root parameters and root/soil processes is a challenge for experimental design data analysis and data application.

12 Root research aims in HMS Aim is to determine - fine root (including mycorrhiza) carbon amounts, carbon allocation into fine root production, carbon amounts and release (decomposition) from fine root litter. - relationships between fine root biomass, stand biomass and litter production, and stand and site factors.

13 Data from manuscript in prep. used in this presentation Helmisaari, Derome & Nöjd Fine root biomass and C & N content in relation to soil properties and stand characteristics in coniferous stands in Finland (in this presentation: stand characteristics) Helmisaari, Nöjd & Lumme: Norway spruce fine roots and seasonal drought results of a three-year field experiment in southern Finland

14 Stands Kevo Sevettijärvi Pallasjärvi Sodankylä Kemijärvi Scots pine Norway spruce Birch Kivalo Oulanka Ylikiiminki Pyhäntä Uusikaarlepyy Lieksa Närpiö Parkano Vilppula Ilomantsi Jämijärvi Ikaalinen Juupajoki Sahalahti Punkaharju Harjavalta Kokemäki Heinola Jokioinen Evo Lapinjärvi Tammela Miehikkälä Ruotsinkylä Virolahti Solböle

16 Fine root biomass larger fine root biomasses in Norway spruce than Scots pine or silver birch, and poorer site types understorey fine root biomasses largest in Norway spruce stands in the north regardless of stand age (more open stands) understorey biomass and litter production estimates important (John Derome and Maija Salemaa) Fine root biomass & needle biomass? (Vanninen & Mäkelä 1999, Scots pine)

17 Fine root / needle biomass ratio Fine root / needle biomass ratio 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 VT-15 VT-40 VT-100 OMaT- 44 Scots pine, Mekrijärvi EMT-58 EMT-88 Norway spruce, Heinola, Kemijärvi & Sodankylä Fine root / needle biomass ratio smaller in Norway spruce than in Scots pine, and smaller in fertile site types, and older stands. ICP-stands under calculation (Marklund s equations, Pekka Nöjd).

18 Production & turnover rate of fine roots Different ways to calculate fine root turnover Variation in turnover and what causes it

19 Comparison of soil core and ingrowth core results for calculating fine root biomass production A 67-year-old Norway spruce stand on a fertile site type in S Finland (Drought/N -experiment, control) Mean annual prod. from soil cores 177 g/m 2 (mean of annual productions 1998, 1999 & 2000 by Fairley and Alexander (1985) equation, differences in living and dead roots between sampling times) Annual prod. from soil cores 260 g/m 2 (in 2000, F & A) Annual prod. from ingrowth cores 268 g/m 2 (increases in bio- and necromass in 2000, F & A) Mean annual prod. from ingrowth cores 201 g/m 2 (biomass+necromass maximums in 2000 divided by 2,5 years, installation of ingrowth cores in May 1998) Larger roots (2-5 mm diameter): Annual root production from soil cores 166 g/m 2. Very little larger roots in ingrowth cores.

20 Comparison of different ways to calculate root turnover rate of Norway spruce roots in 2000 < 2 mm diameter > 2 mm SC IC-1 IC 2 SC GS WH C N D Understorey g/m 2 /year Turnover: (IC 2) SC = prod. soil cores (F&A) / max biom. IC-1= prod. ingrowth cores in the third year in 2000 (F&A) / max biomass GS = growing season ( ) WH = whole year ( ) IC-2= prod. (max. bio- + necromass divided by 2,5 years) / max. biomass

21 Biomass base for turnover rate calculation? SC max SC mean SC min IC C N D D + N Ingrowth core biomass production: C 268 g/m 2 /year N 196 D 253 D + N 184 Soil core biomass (in 2000): SC maximum in 2000: g/m 2 SC mean in 2000: SC minimum in 2000: Ingrowth core biomass: Biomass (min, max or mean) affects the turnover rate!

22 Fine root biomass production of Picea abies with soil cores and ingrowth cores g/m 2 /year Soil cores Ingrowth cores C-1998 C-1999 C-2000 C-2000 Rainy Dry Normal Turnover rate 1998: : : 0.8 Large variation in turnover rate between years!!

23 Large variation in turnover times and rates Root turnover varies e.g. with environmental factors (climate affecting soil environment e.g. drought), site and tree species. Great heterogeneity even in finest roots in the same size class? a part of the fine roots (< 2 mm in diameter) lives for a very short time, average turnover time 3 months (turnover rate 4), a part (many < 0.5 mm in diameter) lives for a very long time (average turnover time 3-5 years, turnover rates ); (Joslin et al. 2003, radiocarbon labeling study with upland oak in Tennessee).

24 Large variation in turnover times and rates Global change models have yet to incorporate the variability in root turnover rates associated with different forest types and/or tree species (Matamala et al. 2003), and maybe even roots of same sizes! Importance of field data!

25 What next, roots in HMS? - Finalising manuscripts!! - those mentioned today - another on fine root biomass & biomass production (with Kirsi Makkonen) - carbon allocation in selected stands (with Pekka Nöjd & co.) - understorey roots (with Maija Salemaa & John Derome) - those in the SNS project Role of roots in carbon cycling in forest soil, minirhizotrone research - Participation in Cost Action E58 Woody Root Processes, data comparison on the same questions Root / soil respiration??

26 Artists eye for beauty or root scientists wishful thinking? Statue by highway E 4 at Östgötaporten

Testing steady states carbon stocks of Yasso07 and ROMUL models against soil inventory data in Finland

Testing steady states carbon stocks of Yasso07 and ROMUL models against soil inventory data in Finland A. Lehtonen 1, T. Linkosalo 2, J. Heikkinen 1, M. Peltoniemi 1, R. Sievänen 1, R. Mäkipää 1, P. Tamminen