important to understand how roots interface with the ecosystem because: roots found in the soil,...
TRANSCRIPT
Important to understand how roots interface with the ecosystem because:
• Roots found in the soil, tree canopies, hyporheic zone, etc. –determined by soil physical & chemical characteristics, amount of soil weathering
• Less weathered soils, root commonly found in the soil while in highly weathered soils rooting in soil is limited
• Soil chemical & physical characteristics control plant species dominance. Plants adapted to soil chemistry through roots.
• Symbionts and root grafting necessary for plants growing in soils with lower nutrient availabilities
• Treating ecosystems with a limiting nutrient may not increase total NPP, just shift allocation of C from belowground
• Land use legacies that alter soil nutrients can affect ecosystem recovery after a disturbance
• Natural disturbances are an important agent of increasing site nutrient availability
Detritus
Plants
Dissolved OM (eg, P, Si, Al)
Other crystalline & non-cryst Al-Silicate PO4
-3 exch sites
Imogolite paracrystalline Al-SilicatePO4
-3 exch sites/complex
Organic exch sites /complex
SOIL
Solution
Mineralization
Uptake
Mineralization
Decomposition
Uptake
LitterfallThe Links between Plants (Belowground) & Soils
Temperate Coniferous Forest Soil
Tropical Forest Soil
•Roots / mycorrhizas found more than 30 meters deep
•Roots not just found in soils
•Old soils
•Soils low in Ca, K, N (except where N fixing trees for coffee)
•Roots / mycorrhizas found mainly in the soil
•Young soils
•Soil nutrient availabilities decrease with land-uses (i.e. acid precipitation)
Root excavation for tracking disease in Washington (photo Bob Edmonds)
http://www.hubbardbrook.org/research/gallery/soil/HB_115_Spodosol.jpg
Leached layers where nutrient availability is low
Layers that are impermeable to easy root penetration so restrict roots to surface horizons
Pacific silver fir tip-over, Findley Lake, Washington
Root tip-over, Kenai, Alaska
Canada – Root excavation
Root growth is extensive – can be 30 meters from base of the tree
Roots are growing to available nutrients
http://green.nationalgeographic.com/environment/photos/rainforests-tropical/rhinohornbilldipterocarp.html
Sparse palm trees spread across the savanna of Madagascar. Photograph by Maria Stenzelhttp://green.nationalgeographic.com/environment/photos/savannah/palmdottedsavannah.html
Greater rheas graze in the tall savannah grass of Brazil's Pantanal. Photograph by Joel Sartorehttp://green.nationalgeographic.com/environment/photos/savannah/rheasgraze.html
http://travel.mongabay.com/malaysia/images/malaysia1016.html
http://travel.mongabay.com/indonesia/images/singapore5485.html
http://travel.mongabay.com/indonesia/images/singapore5456.html
OR roots do not remain in the soil
Apogeous roots of Tabonuco climbing up a Sierra palm to acquire stem flow nutrients, Luquillo LTER, Puerto Rico
Roots in streams
Nodules of nitrogen fixing tree species (e.g. Inga spp.)
Root - fungal mats accessing nutrients
Tabonuco root mat (> 40 cm deep) on the surface of the forest floor, Luquillo LTER, Puerto Rico
Root grafting between different species of plants and borrowing C, nutrients from other plants
Root rot disease transmitted through root grafts – western hemlock (photo Bob Edmonds)
10 year old Site Class II [HIGH SITE QUALITY] Douglas-fir, Washington (note person in photo)
Person
Tree height
10 year old Site Class IV [LOW SITE QUALITY] Douglas-fir, Washington (note person in photo)
Douglas-fir(% of Total Annual Production)
0
10
20
30
40
50
60
70
Aboveground Belowgr > 2mm Belowgr < 2mm
ControlFertilized
30%
18%
Nutrient Availability
Water Availability
Leaf Area
Root Area
Regulation point
What controls how much roots are produced?
Oa
E
Bhs
OeOi
Root appearance when not affected by high aluminum levels and properly functioning roots
Roots dying from aluminum toxicity and no longer able to take up nutrients
Image of roots taken in spruce forests in Germany where trees were dying from acid rain
Abies amabilis, WA
01
2
3
4
5
6
7
8
9
Oa E Bhs Litterfoliage
ForestFloor
Ca/Al ratio
Fine roots < 1mm diam
Ca/Al ratio -< 0.2 critical, mortality
10 parts Ca and 50 parts Al = 0.2 ratio
10 Ca, 1 Al
10 Ca, 11 Al10 Ca,
50 Al
10 Ca, 100 Al
0
100
200
300400
500
600
700
800
900
1000
Forest floor E Bhs
ppmx10MRT, yrs
Aluminum in Roots by HorizonMRT = mean residence time (yrs) of decaying roots
0
510
1520
2530
3540
4550
A. amabilis T. mertensiana
foliagebolewoodroots <1 mm
Al accumulator- foliage 500-1,120; fine roots 1320 ppm
Not Al accumulator - foliage 110-260; fine roots 730 ppm
Wet Nitrate Deposition (kg/ha) 1995-1998NADP/NTN Monitoring Data
http://www.hubbardbrook.org/research/gallery/soil/HB_115_Spodosol.jpg
Spruce dominated stands with
co-associates fir, birch,
maple
SP
OD
OS
OL
NY
aa
b
bb
bba
Between 1992-1998, BOLEWOOD GROWTH:N, Ca/N, Ca significantly increased in NY;N significantly increased in NH
a b b b
b b ba
a a
bb
0
1
2
3
4
5
6
7
8
9
Control Calcium Ca + N Nitrogen
ANPP
(Mg
ha-1
yr-1
)
Wood
Foliage
0
1
2
3
4
5
6
7
8
9
Control Calcium Ca + N Nitrogen
ANPP
(Mg
ha-1 y
r-1)
Wood
Foliage
ab b
b
b b ba
NY
a
b bb
a a
ab
b b
b b
bb
a a
NH
Between 1992-1998,FOLIAGE GROWTH:
N, Ca/N or Ca significantly increased in NY, NH
ANPP - Tree Species compared to Controls (significant only)
Picea rubens (spruce)
Abies balsamea(fir)
Acer spp. (maple)
Betula spp. (birch)
New York – N saturation stage II
Ca
Ca + N
N
Vermont – N saturation stage I
Ca
New Hampshire – N saturation stage I
Ca
Ca + N
N
After 6 years treatment
http://www.mnwetlands.umn.edu/tour/tour_images/vege1.jpg
Aerenchyma - secondary respiratory tissue or modified
periderm, found in many aquatic plants and
distinguished by the large intercellular spaces
Invasive plants without aerenchyma not persist in these environments with high rainfall
http://luq.lternet.edu/research/projects/environmental_setting_description.html#Figure1
Forests almost
completely cleared in
early 1900s
Subtropical forests with
strong legacies of agriculture
i.e. fruit trees, N-
fixing trees used to
shade coffee plants
Soil characteristicsSite Total Soil
N%
NO3--N
mg/kg/mo
El Verde 0.34 0.6
Bisley 3 0.29 1.6
Bisley 5 0.37 6.6
Date
Ba
sal A
rea
In
cre
ase
(cm
2 )
0
20
40
60
80
100EVB3B5
Agriculture N legacy – coffee with N-fixing trees
Agriculture legacy – but no coffee with N-fixing trees,
had houses & farms because of royal palms
Hurricane Georges hits Puerto Rico on September 21, 1998. Image by Dennis Chesters, Marit Jentoft-Nilsen, Craig Mayhew, and Hal Pierce, Laboratory for Atmospheres, NASA Goddard Space Flight Center from data derived from NOAA GOES-8 satellite. Image from "http://rsd.gsfc.nasa.gov/rsd/images/Georges.html".
6 Hurricanes during ~ 10 yr study:
Sept 1989 – Hugo;early-mid Sept 1995 –
Luis & Marilyn;Jul 1996 – Bertha;Sept 1996 -Hortense;Sept 1998 - Georges
Foliage decay < 6 months so pulse of nutrients available;
however, foliage area takes several years to
re-establish
Date
Ba
sal a
rea
gro
wth
ra
te (
cm2 d
ay-1
)
0.02
0.04
0.06
0.08
0.10
0.12
0.14
Wood RemovalWood AdditionControl
Wood removal
Wood addition
Root growth increased with wood
addition
http://luq.lternet.edu/data/lterdb09/data/CTE-photos/coqui10.JPG
1 m2 calling area for mates at night
Amount habitat increases significantly with hurricanes
Important to understand how roots interface with the ecosystem because:
• Roots found in the soil, tree canopies, hyporheic zone, etc. –determined by soil physical & chemical characteristics, amount of soil weathering
• Less weathered soils, root commonly found in the soil while in highly weathered soils rooting in soil is limited
• Soil chemical & physical characteristics control plant species dominance. Plants adapted to soil chemistry through roots.
• Symbionts and root grafting necessary for plants growing in soils with lower nutrient availabilities
• Treating ecosystems with a limiting nutrient may not increase total NPP, just shift allocation of C from belowground
• Land use legacies that alter soil nutrients can affect ecosystem recovery after a disturbance
• Natural disturbances are an important agent of increasing site nutrient availability