This document discusses fine root dynamics in trees. It begins with an introduction to fine roots, noting their key characteristics and role in nutrient cycling. It then covers various methods to estimate fine root production and biomass, including direct methods like ingrowth bags and sequential coring, and indirect methods like nitrogen budgeting and allometric equations. Factors that influence fine root production are also examined, such as CO2, soil depth, stand management, and stand age. The document concludes with tables summarizing estimated fine root production values across different ecosystems and forests. It identifies a need for more research on fine root production of tropical species and their nutrient recycling roles at the ecosystem scale.

1. 1
Fine Root Dynamics in Trees
Vikas Kumar
2013-27-102
Dept. of Silviculture & Agroforestry
College of Forestry, KAU, Thrissur
Mo. No.: 9995093698
Email ID: vkskumar49@gmail.com
PhD second seminar

2. Contents
Introduction
Fine Root Production/ Biomass (FRP/FRB)
Method of estimation of FRP
Factors influence FRP
FRP research in various ecosystems
Conclusion
Future line of work
2

3.  Non-woody and having <2 mm diameter (Zobel and Waisel, 2010).
 High biological activity and resource cycling.
 Short life span and continuous turnover (van Noordwijk et al., 1994).
Aboveground litter and belowground fine roots are the principal components of
nutrient cycling- adding to soil carbon and nutrient pools (Finner et al., 2011).
Introduction
3

4. • Fine root Production/Biomass:
• Forest ecosystems - the belowground biomass accounts for 13-25% of the total stand
biomass and fine roots represent of 2-15% (Helmisaari et al., 2002).
• FRP >40% of NPP in forest because of their high turnover rate where as 10-30% of NPP
of temperate ecosystems
• Aboveground rate of litter decomposition contributed 19% and belowground litter
decomposition contributed 58% to total soil respiration in coniferous forest (Finer et al.,
2011).
• Lacking of technical and methodological information in tropical woody ecosystems.
4

5. Fine root biomass and production
Direct method
i. Ingrowth method
ii. Root mesh method
iii. Sequential core method
iv. Minirhizotron method
Indirect method
i. Nitrogen (N) budget approach
ii. Allometric equations
Methodology
5

6. • It also known as ‘Mesh bag method’.
• Most promising approach in grassland and forestry (Hendricks et al., 2006).
• It determines FRP per unit area and time (Mgha-1yr-1) (Steingrobe et al., 2001).
• It gives the quantitative information on fresh FRP by accessing fine root ingrowth into specific volume of
root free soil in mesh bag.
• Perfolatorated aluminum circular mesh bag of size 30 cm length and 15-20 cm diameter.
Ingrowth Method
Direct method
6

7. Mesh bag installation
Retrieval of Mesh Bags
Figure 1. Diagrammatic representation of mesh bag installation 7

8. 1. High disturbance to root and rooting environment.
2. Physical properties may change especially BD.
3. Severing of the roots may lead to fine root proliferation and hence may lead to
over estimation.
4. Decomposition is not quantified.
Limitation of Ingrowth method
8

9. a. Positive increment approach
9
Pa= Fine root production over the whole sampling.
N= Number of days throughout the study period after mesh bag installation.
Pi, j= FRP after i month of regrowth (2,3,4...) during sampling period during j season.

10. • Mean biomass and necromass in all season.
• Pa= FRP over the whole sampling year.
• P3, j= FRP after 3 months of regrowth during sampling period.
b. Short term cores approach
10

11. The following procedure as follows:
I. Take a straight stainless steel blade size (10 x 30 x 0.2 cm) and push into the soil surface
up to depth of 20 cm.
II. A nylon mesh size (10 x 10 x 0.1 cm) fit between two thin straight stainless steel sheets
(10 x 30 x 0.1 cm) attach to a single handle.
III. The apparatus containing the mesh insert gradually into the slit, along the inserted blade.
IV. The blade was removed slowly from the slit.
V. The handle of the apparatus made of two thin stainless steel sheets remove and each sheet
individually extracted from the slit, leaving the mess insert vertically in the soil.
Root Mesh Method
11

12. Fig 2. Root Mesh Method: (A). A straight and sharp stainless steel blade for the making the soil slit, two thinner
stainless steel sheets for placing the mesh, and a nylon mesh sheet; (B). Photos of each step in the procedure; and
(C). Schematic illustration of the procedure
Figure 2. Diagrammatic representation of Root mesh bag installation 12

13. • Fine root production and necromass over time.
• Carried out repeatedly in the same location to establish inter annual variation.
• Sum of all fine root biomass between growing seasons on a year.
Sequential Coring
13

14. Figure 3. Diagrammatic representation of the sampled plots for sequential core method
Retrieval of Mesh Bags

15. • Based on three assumptions of dying of fine root dynamics (Osawa and Aizawa, 2012).
• Fine root production (gij) = Bj − Bi + Nj − Ni + dij
Here, B= Live fine roots; N= Fine root necromass and dij =Decomposition between times i and j
• Mortality (mij) = Nj − Ni + dij
• Decomposition (𝑌𝑖𝑗) = 1 − )( 𝑒 −𝑦∆𝑡
a. Compartment Flow approach
15

16. • Annual fine root production (Pa(MM)) = (Bmax –Bmin)
• Necromass not considered.
b. Maximum-Minimum approach
16

17. • Annual fine root production (Pa(MM)) = ƸP
• The production (P) between two sampling dates is calculated either by adding the differences in
biomass (ΔB) and necromass (ΔN), or by adding only the differences in biomass (ΔB), or by equaling
P to zero (Fairley and Alexander 1985).
I. P= ΔB + ΔN a) if biomass and necromass have increased; and b) If biomass has decreased and
necromass has increased.
II. P = ΔB if biomass has increased and necromass has decreased
III. P= 0 a) if biomass and necromass have decreased.
c. Decision Matrix approach
17

18. • Fine root production, longevity, mortality of fine root fractions (<2 mm) through the
minirhizotrons of transparent tubes.
• Video photography has been using to measure root activity.
• Image analysis helps to take several parameters viz., root length, root width, root
thickness, longevity, root density, root formation pattern, root structure, mortality period
(depend on species, climatic and edaphic factor) and other physical appearances such as
colour and colonization.
Minirhizotrons Method
18

19. Figure 4. Diagrammatic representation of minirhizotron installation 19

20. Limitations:
I. Difficulty during ascertaining process.
II. Roots are only classified as dead when they disappear, the overall root longevity may be either
overestimated or underestimated.
III. Cost involved is high.
20

21. • Annual N allocation to FR= Difference between net N mineralization in soil and net N flux into
aboveground tissues.
• FRP = Production of annual N allocation to fine roots and the C:N ratio in fine roots (Aber et., 1985).
• N budget approach to work the following information:
i. N inputs into an ecosystem,
ii. N storage in all plant tissues, and
iii. N mineralization rates in the soil.
• Several assumptions:
i. No N retranslocation from roots,
ii. Steady-state conditions,
iii. Mineralizable N is totally taken up by plants, and
iv. N limits plant growth.
Nitrogen (N) Budget Approach
Indirect method
21

22. • FRB can also be estimated based on easily measurable aboveground metrics such as basal
diameter, DBH, height and crown foliage (Ammer and Wagner, 2002).
• These models function on the basis of a strong relationship between FRB and aboveground
variables at both tree and stand-levels, although this may not apply to all sites (Jurasinski et
al., 2012).
Allometric equations method
22

23. Limitations
• Leading to uncertainties in the estimates they produce (Jurasinski et al., 2012).
• Unable to reflect the high temporal and spatial heterogeneity in FRB distribution common in most
ecosystems (Zerihun et al., 2007).
• Some of the assumptions used to parameterize models may not hold true for all tree species and
ecosystems (Lee et al., 2004).
23

24. 24
Figure 5. Relationships between aboveground biomass and fine root biomass and total root biomass for softwood (A)
and hardwood (B) species (Kurz et al., 1996).

25. 25
Figure 6. Relative fine root biomass (rFRB) of a tree in relation
to the distance (from the stem trunk and diameter a: breast
height (dbh) as assumed by the model) (Ammer and Wagner,
2004).
Figure 7. The relationship between decomposition rates of leaf litter
versus fine root in Pinus massoniana (filled square), Castanopsis hysrix
(open triangles), Michelia macclurei (open circles) and Mytilaria
laosensis (open square) plantations (Wang et al., 2010).
Figure 8. Production of fine root biomass in total root
biomass (Kurz et al., 1996).
Figure 9. Fine root production as a function of fine root biomass.
Symbols indicate the data point for the different species groups:
softwood (A) and hardwood (B) (Kurz et al., 1996).

26.  TBmax = (Pa)/ Bmax
 RT unit as yr—1
 The influence of fine root turnover, depends on
(i). Soil stratification;
(ii). Soil depth;
(iii). Root diameter;
(iv). Number of samplings per year.
Fine root turnover
26

27. Factors influencing FRP/FRT
CO2
 Soil depth
 Stand management
 Species composition
 Stand age
 Season
 Soil nutrients
 Soil pH
 Basal area
27

28. Figure 10. A conceptual model of deeper rooting distributions under elevated CO2 concentration (Iversen, 2010).
CO2
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29. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
FINE ROOT (0-20 CM) FINE ROOT (20-40 CM) FINE ROOT (0-40 CM)
0.3
0.12
0.43
0.77
0.17
0.94
Finerootbiomasskg/m2
Soil profile
Hill-slope forest Gallery Forest
Figure 11. Fine root biomass in the two forests grove overall profile
Republic of the Congo (Ifo et al., 2015).
Soil depth
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30. Figure 12. Fine root biomass and necromass in the four forest use types according to the fine root inventory (50
cm depth) in forest-use type.
University of Göttingen, Germany (Harteveld et al., 2007)
Stand management
30
A: Undisturbed natural
forest (NF)
B: NF with little timber
extraction
C: NF with substantial
timber extraction
D: Cacao plantation under
natural shading trees

31. Figure 13. Annual fine root production calculated (a). In growth core method and (b). In different soil
layer by sequential coring method in three different stands (n=3) of Larix principis-rupprechtii.
Beijing Forestry University, China Wang et al., 2014
Stand age
31

32. Figure 14. Distribution of fine roots (< 2 mm) at two soil depths (□ 0 - 15 and ■ 15 - 30 cm) in the three stands.
W- winter, S- spring, R- rainy and A- autumn.
North Eastern Regional Institute of Science & Technology, Arunachal Pradesh (Barbhuiya et al., 2012)
Season
32

33. Figure 15. Relationship between fine root production and basal area of the stands.
University of Göttingen, Germany (Harteveld et al., 2007)
Basal area
33
A: Undisturbed natural
forest (NF)
B: NF with little timber
extraction
C: NF with substantial
timber extraction
D: Cacao plantation under
natural shading trees

34. Table 1. Fine root production in various ecosystem
Ecosystem Fine root production (Mg ha−1yr−1) References
NATURAL FOREST
Tropical moist deciduous forest 8.32-8.9 Kubisch et al., 2016
Tropical broadleaf’s evergreen forest 0.6 to 22.7 Yang et al., 2004
Evergreen broad-leaved forest in SW Japan 6.3 to 9.4 Sato et al., 2015
Dry tropical forest NE India 2.9 to 5.3 Singh et al., 2011
Undisturbed forest stand, Nepal 6.67 Gautam et al., 2016
Disturbed forest stand, Nepal 3.35 Gautam et al., 2016
Subtropical forest 1.1 to 10.6 Yang et al., 2004
Disturbed subtropical humid forest NE India 5.9 – 7.7 Arunachalam et al., 1996
Temperate forest 0.5 to 10 Vogt et al., 1986
Boreal forest 1.51 to 5.28 Yuan and Chen, 2010
Mono and multispecific forest plantations in the Amazon 3.1 to 14.3 Barlow et al., 2007
Regrowth forest 8.64±0.08 Silva et al., 2011
PLANTATION
Teak plantation in dry tropics, Chhattisgarh 4.80 to 9.81 Sahu et al., 2013
Poplar plantations (5 to 8 yrs.) in Central Himalaya 1.0 to 1.2 Lodhiyal et al., 1995
6-yr old Schizolobium-based plantation forests (Monospecific) 5.92±0.15 Silva et al., 2011
6-yr old Schizolobium-based plantation forests (Mixure) 6.08±0.13 Silva et al., 2011
AGROFORESTRY
6-yr old Schizolobium-based plantation forests (Agroforestry) 6.63±0.13 Silva et al., 2011 34

35. Forest type Location Methodology Fine root production
(g m-2yr-1)
Source
Amazonian Tropical forest San Carlos,
Venezuela
Ingrowth core (30 cm) 806 Cuevas and Medina (1988)
Amazonian Tropical forest
(sandy soil)
Para, Brazil Ingrowth core (30 cm) 400 Metcalfe et al. (2008)
Amazonian Tropical forest
(clay soil)
Para, Brazil Ingrowth core (30 cm) 400 Metcalfe et al. (2008)
Semi-evergreen forest Barro Colordo
Island, Panama
Ingrowth core (25 cm) 352 Cavelier et al. (1999)
Semi-evergreen forest Kodayar, South
India
Ingrowth core (25 cm) 185.9 Sundarapandian and Swamy
(1996)
Deciduous tropical forest Kodayar, South
India
Ingrowth core (25 cm) 185.9 Sundarapandian and Swamy
(1996)
Tropical dry forest Jalisco, Mexico Sequential core (10 cm) 180.5 Castellanos et al. (2001)
Tropical dry evergreen
forest
Coromandel, India Ingrowth pit (10 cm) 117.1 Visalakshi (1994)
Table 2. Fine root production in tropical forests
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36. Conclusions
• Fine roots- the below ground litter- important role in nutrient cycling.
• Production of fine roots are influence on CO2, soil depth, stand management, stand age, season
and basal area.
• Controversy exists in the literature on what are the best methods to use (direct or indirect
approaches) for estimating the biomass and production of fine roots at an ecosystem level.
• Generally estimation of fine root production is through combination of methods such as
ingrowth method and sequential coring method.
• It suggests that the direct methods should still be utilized when studies are being initiated on a
new site.
36

37. Future lines
• Little information is available about fine root production of different tropical broad leaf
species.
• Nutrient recycling role of fine roots have to be studied in much larger scale i.e. in ecosystem
level.
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