Download pH and Plant Distribution

The relationship of pH to plant
distribution in nature
Dr Herman Kurz
The American Naturalist,
Vol. 64, No. 693.
(Jul. - Aug., 1930), pp. 314-341
Overview
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Part A: pH and Plant Distribution
Part B: Ecology
Part C: Plant Distribution in General
pH
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Sörenson (1909) was involved in work testing the acidity of
beer and the pH symbol rooted in the French "pouvoir
hydrogene" (power of hydrogen)
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pH = -log[H+]
pH and Plant Distribution
pH as a factor in plant distribution?
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Wherry (1916) was first to consider pH as an
explanation for plant distribution
Scientists divided (as of 1930)between
considering pH “the factor; a factor [or]
unimportant in their species”
pH and Plant Distribution
Members of the plant kingdom investigated
Seed plants:
- ericads and orchids found in acidic soils
- trees and herbaceous flowering plants of forests tolerate
a wide range
Ferns:
- tolerate wide range of acidity
- there is a relationship between soil acidity and
geographic range but there are also other factors at work
(Wherry and Steagall)
Mosses and liverworts:
- are not sensitive to reactions and general conclusions
not warranted
pH and Plant Distribution
Algae:
Wehrle (1927) 4 classifications of algal habitats
1.
High constant acidity = ↓ species ↑ individuals
2.
High constant alkalinity = ↓ species ↑ individuals
3.
Weakly acidic conditions (pH 5-7) = ↑ species
4.
Varied alkalinity (without lime) = ↑ species
Some species with narrow ranges and some with wide ranges
pH and Plant Distribution
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acidity in these habitats changes spatially and
temporally (unless strongly buffered) and is due to
CO2
Reaction: CO2 + H2O ⇌ H2CO3
H2CO3 ⇌ HCO3− + H+
Stratification is due to:
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more photosynthesis occurring in surface layers throughout
the day
more respiration occurring at lower layers (mud organisms)
pH and Plant Distribution
pH and Plant Distribution
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Ulehla (1923) performs experiments algae with
psychohormia
2 treatments for 30 minutes:
1. Light exposure: pH changed from 6.9-7.0
2. Dark: pH changed from 5.85-6.18
after algae was kept in the dark for 48 hrs they died
In nature algae are often found on shell animals
(where their calcareous shells keep the environment
locally neutralized)
pH and Plant Distribution
Lichens:
- pH is considered a secondary factor in
distribution (found in narrow ranges) to
ammonium content
pH and Plant Distribution
Special pH correlations
pH, leaching and successions:
- Salisbury (1921) showed that leeching and removal
of carbonates results in increased acidity
- Seen in oak forest invading hill tops as humus and
acidity develop
- Leeched soil may be deposited at slope base
(encouraging acid loving vegetation)
- In general he saw forests advancing downward
progressive downward leeching
pH and Plant Distribution
pH and Plant Distribution
pH and soil profiles:
- Braun-Blanquet and Jenny (1926) showed 4
stages of humus development along with
successional vegetation
- Geisler (1926) saw no relationship between
pH and plant successions and found that
climax communities had a wider range of
acidity than the pioneer
pH and Plant Distribution
pH and Plant Distribution
Influence of plants on pH:
- plants alter the soil they are in
- Arrhenius (1926) thought that plants change
their environment to what is most suitable for
them
- Chodat (1924) thought that each plant alters
its environment by making it more favorable
for successors (agrees with other
successional theories)
pH and Plant Distribution
pH and Species Characters:
Clausen (1922) found 2 species to grow at
intermediate forms in neutral soils
pH and Concomitants:
other factors need to be considered
a. pH constant but other factors variable
b. pH varied and other factors constant
pH and Plant Distribution
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Kotilainen (1927) found good correlation
between pH and plant distribution but still
considers pH and secondary or unimportant
although certain vegetation occurs within
narrow ranges, acidity itself is an indicator of
other edaphic conditions
critical of other studies that alter acidity, as
this changes other factors as well
pH and Plant Distribution
Kotilainen (1927) continued
- Sphagnum can stand alkaline soil water if its
low in nutrient salts
- Water level, electrolyte concentration,
calcium ions and oxygen content are more
direct factors (are often the producers of
acidity)
pH and Plant Distribution
Salt and water and pH:
- Montfort and Brandrup (1927) looked at the
distribution of salt marsh plants
- other factors (salinity and flooding) outweigh
and pH is not important
Ecology
Plant Ecology
G. E. Nichols.
Ecology, Vol. 9, No. 3. (Jul., 1928), pp. 267-270.
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Ecology was 1st introduced in 1885 (by zoologist Reiter)
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clearly defined the following year (by zoologist Haeckel)
" the science treating of the reciprocal relations of organisms
and the external world."
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" If the botanists persist in appropriating the term ecology as
synonymous with plant ecology," we are warned, " we shall be
forced to domesticate the new term bio-ecology to take its place
as referring to the whole field.“
Ecology
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‘The student of plant ecology and the student of animal ecology
have many points of interest in common. They consider their
material from essentially the same points of view. Up to a
certain point, they may work with the same materials. Each, in
his own field, may contribute much to supplement the work of
the other. But, after all is said and done, with rare exceptions,
the modern ecologist, both by training and experience, is either
a botanist or a zoologist. In other words, just as the general
biologist of the past generation has given way to the plant
scientist and the animal scientist, so the modern ecologist
almost inevitably is either a plant ecologist or an animal
ecologist.’
Ecology
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‘Plant ecology has made great progress
during the past twenty-five years. Formerly
looked upon as a helpless infant, and later as
the playful child (in the opinion of some, the
bad boy) among the plant sciences, it has
grown to be an active-minded, healthy youth.
It has even acquired a certain amount of
dignity and self-respect, although it is still far
from mature.’
Ecology
Ecology: Theories and Applications 4th Ed
Peter Stiling, 2002
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Life is not evenly distributed on Earth and ecology
seeks to explain this phenomenon
Ecology is the study of interactions among
organisms and their environment, including the study
of individuals, populations, communities and
ecosystems
4 broad areas: behavioral, population, community
and ecosystems
Ecology
Physical Environment
Physical variables commonly limit the
abundance of plants and animals and are
divided into 2 groups:
- those used as resources (nutrients, CO2,
H2O)
- Those which are not used but are critical to
survival (temperature, wind, pH)
Ecology
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Robert Whittaker, 1967 (plant ecologist)
formalized the concept that community is
governed by physical variables (physical
factors affect distribution patterns, species
abundance and species richness)
considered an environmental gradient
Ecology
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Examined vegetation along an elevation gradient in
mountain ranges (western US), along with various
abiotic factors
Whittaker observations agreed with “the principle of
species individuality” (asserted by Gleason in 1926)
Concluded that composition of species at any one
point in the environment was determined largely by
physical factors
What about biotic factors?
Ecology
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Assembly rules were first introduced by Diamond (1975)
“How are communities assembled from species pools?”
Speciation
POOL
Extinction
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COMMUNITY
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looked at bird species on islands (niche space and competition)
physical environment did not change (but resources did due to
changes in island size)
Ecology
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Centrifugal organization
in a salt marsh:
simple habitats
stressful
display strict zonation
patterns
Waterlogging
Optimal
Habitat
Salinity
Ecology
Salinity (psu)
25
Water Content (%)
15
20
30
30
35
40
45
50
55
60
Ecology
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Pennings, Grant and Bertness (2005) showed that
stress tolerant species survived when moved into a
less stressful zone ONLY if neighbors were not
present
species in less stressful zones could not survive
when moved to stressful zones
Do trade-offs between competitive ability and stress
tolerance exist within the plant species of a salt
marsh community?
Ecology
Where is the science now?
How Do Communities Come Together?
Nicholas J. Gotelli (1999)
- 25 years after publication, Diamond’s ideas
on assembly rules are still studied and hotly
debated
Ecology
The Influence of Environmental Factors on the
Distribution of Freshwater Algae: An Experimental
Study: II. The Role of pH and the Carbon DioxideBicarbonate System
Brian Moss (1973)
 Contrasted levels of several common ions present in
different freshwaters could help to explain the
differential distribution of eutrophic and oligotrophic
algae noted in Part I (Moss 1972)
Ecology
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Bicarbonate levels increase markedly from those in
the softest oligotrophic waters to those in the
eutrophic waters of soft rock areas, and pH tends to
increase with bicarbonate level.
The availability of free CO2 decreases, at constant
bicarbonate level, with increasing pH and increases,
at constant pH, with increasing bicarbonate
The combined effect is usually an overall decrease
in availability of free CO2, with increasing hardness
of natural waters.
Ecology
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Looked at growth rates of species in relation to pH
No pattern was found in the minimum pH tolerated.
Most would not grow at pH values lower than 4.5-5.1, though
the exact minima lay somewhere above pH 3.8
Distinct differences were found in the maximum pH tolerated by
the eutrophic and oligotrophic groups
Most oligotrophic species would not grow at pH values above
8.85, and the actual maxima recorded were 8.6 or less.
This contrasts with growth of
typical eutrophic algae where very high rates were maintained
between pH 8.4 and 9.3 or above.
Ecology
There are several ways in which high pH might exclude oligotrophic
algae from eutrophic waters:
(1) an intrinsic effect of pH on enzymes, in the cell wall or membrane,
responsible for uptake of one or more essential nutrients;
(2) inability of oligotrophic species to absorb trace elements present in low
concentration at high pH;
(3) a toxic effect of relatively high total dissolved ion content associated
with high pH;
(4) Coprecipitation of phosphate with calcium, magnesium, and carbonate
at high carbonate levels;
(5) a direct toxic effect of carbonate or of hydroxide ions, levels of which
increase with increasing pH;
(6) differential availability of different inorganic carbon compounds for
photosynthesis.
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Ecology
Current work on pH in ecology
Local plant diversity patterns and evolutionary history at a regional
scale
Meelis Partel 2002
- Used published studies
- positive relationships between species richness and pH were
significantly more probable when evolutionary centers were on
high pH soils
- negative relationships between species richness and pH were
significantly more probable when evolutionary centers were on
low pH soils
- soil pH increases with latitude, so there is also a positive
relationship between richness and pH at high latitudes and
negative at low latitudes
Ecology
Ecology
Implications? Why study at all?