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TitlePrinciples of Terrestrial Ecosystem Ecology, 2nd Edition
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Table of Contents
                            Cover
Principles of Terrestrial Ecosystem Ecology, 2nd Edition
ISBN 9781441995032
Preface
Contents
Part I: Context
	1: The Ecosystem Concept
		Introduction
		A Focal Issue
		Overview of Ecosystem Ecology
		History of Ecosystem Ecology
		Ecosystem Structure and Functioning
			Ecosystem Processes
			Ecosystem Structure and Constraints
		Controls Over Ecosystem Processes
		Human-Induced Ecosystem Change
			Human Impacts on Ecosystems
			Resilience and Threshold Changes
			Degradation in Ecosystem Services
		Summary
		Review Questions
		Additional Reading
	2: Earth’s Climate System
		Introduction
		A Focal Issue
		Earth’s Energy Budget
		The Atmospheric System
			Atmospheric Composition and Chemistry
			Atmospheric Structure
			Atmospheric Circulation
		The Ocean
			Ocean Structure
			Ocean Circulation
		Landform Effects on Climate
		Vegetation Influences on Climate
		Temporal Variability in Climate
			Long-Term Changes
			Anthropogenic Climate Change
			Interannual Climate Variability
			Seasonal and Daily Variation
			Storms and Weather
		Relationship of Climate to Ecosystem Distribution and Structure
		Summary
		Review Questions
		Additional Reading
	3: Geology, Soils, and Sediments
		Introduction
		A Focal Issue
		Controls Over Soil Formation
			Parent Material
			Climate
			Topography
			Time
			Potential Biota
			Human Activities
		Controls Over Soil Loss
		Development of Soil Profiles
			Additions to Soils
			Soil Transformations
			Soil Transfers
			Losses from Soils
		Soil Horizons and Soil Classification
		Soil Properties and Ecosystem Functioning
			Soil Physical Properties
			Soil Chemical Properties
		Summary
		Review Questions
		Additional Reading
Part II: Mechanisms
	4: Water and Energy Balance
		Introduction
		A Focal Issue
		Surface Energy Balance
			Radiation Budget
			Partitioning of Absorbed Radiation
		Box 4.1	The Energetics of Water Movement
		Overview of Ecosystem Water Budgets
		Water Inputs to Ecosystems
		Water Movements Within Ecosystems
			Water Movement from the Canopy to the Soil
			Water Storage and Movement in the Soil
			Water Movement from Soil to Roots
			Water Movement Through Plants
				Roots
				Box 4.2	Tracing Water Flow Through Ecosystems
				Stems
				Leaves
		Water Losses from Ecosystems
			Evaporation from Wet Canopies
			Evapotranspiration from Dry Canopies
			Changes in Storage
			Runoff
		Summary
		Review Questions
		Additional Reading
	5: Carbon Inputs to Ecosystems
		Introduction
		A Focal Issue
		Overview of Carbon Inputs to Ecosystems
		Biochemistry of Photosynthesis
		Pelagic Photosynthesis
			Light Limitation
			CO 2 Supply
			Nutrient Limitation
			Pelagic GPP
		Living on the Edge: Streams and Shorelines
		Terrestrial Photosynthesis
			Photosynthetic Structure of Terrestrial Ecosystems
			C 4 Photosynthesis
			Box 5.1 Carbon Isotopes
			Crassulacean Acid Metabolism
			CO 2 Limitation
			Light Limitation
			Nitrogen Limitation and Photosynthetic Capacity
			Water Limitation
			Temperature Effects
			Pollutants
		Terrestrial GPP
			Canopy Processes
			Leaf Area
				Length of the Photosynthetic Season
			Satellite-Based Estimates of GPP
		Summary
		Review Questions
		Additional Reading
	6: Plant Carbon Budgets
		Introduction
		A Focal Issue
		Plant Respiration
		What Is NPP?
		Marine NPP
		Lake NPP
		Stream and River NPP
		Terrestrial NPP
			Physiological Controls Over NPP
			Environmental and Species Controls Over NPP
		Allocation
			Allocation of NPP
			Allocation Response to Multiple Resources
			Diurnal and Seasonal Cycles of Allocation
		Tissue Turnover
		Global Distribution of Biomass and NPP
			Biome Differences in Biomass
			Biome Differences in NPP
		Summary
		Review Questions
		Additional Reading
	7: Decomposition and Ecosystem Carbon Budgets
		Introduction
		A Focal Issue
		Overview of Decomposition and Ecosystem Carbon Balance
		Leaching of Litter
		Litter Fragmentation
		Chemical Alteration
			Fungi
			Bacteria and Archaea
			Soil Animals
		Temporal and Spatial Heterogeneity of Decomposition
			Temporal Pattern
			Vertical Distribution
		Box 7.1 Isotopes and Soil Carbon Turnover
		Factors Controlling Decomposition
			Litter Quality
			Rhizosphere Stimulation of Decomposition
			Microbial Community Composition and Enzymatic Capacity
			The Environment
				Moisture
				Temperature
			Soil Organic Matter
				Soil Properties
				Soil Disturbance
				Humus Formation
			Peat Accumulation and Trace Gas Emissions
		Heterotrophic Respiration
		Net Ecosystem Production (NEP)
		Box 7.2 Measuring Carbon Fluxes of Ecosystems and Regions
		Net Ecosystem Carbon Balance
			Gaseous Carbon Fluxes
			Particulate Carbon Fluxes
			Dissolved Carbon Fluxes
		Stream Carbon Fluxes
			Stream Decomposition
			Stream Carbon Budgets
		Lake Carbon Fluxes
		Ocean Carbon Fluxes
		Carbon Exchange at the Global Scale
		Summary
		Review Questions
		Additional Reading
	8: Plant Nutrient Use
		Introduction
		A Focal Issue
		Overview
		Ocean Ecosystems
		Lake Ecosystems
		Rivers and Streams
		Terrestrial Ecosystems
			Nutrient Movement to the Root
			Diffusion
			Mass Flow
			Root Interception
		Nutrient Absorption
			Nutrient Supply
			Development of Root Length
			Mycorrhizae
			Nitrogen Fixation
			Root Absorption Properties
		Nutrient Use
		Nutrient Loss from Plants
			Senescence
			Leaching Loss from Plants
			Herbivory
			Other Avenues of Nutrient Loss from Plants
		Summary
		Review Questions
		Additional Reading
	9: Nutrient Cycling
		Introduction
		A Focal Point
		Overview of Nutrient Cycling
		Marine Nutrient Cycling
			Large-Scale Nutrient Cycles
			Estuaries
			Coastal Currents
		Lake Nutrient Cycling
		Stream Nutrient Cycling
		Nitrogen Inputs to Terrestrial Ecosystems
			Biological Nitrogen Fixation
				Groups of Nitrogen Fixers
				Causes of Variation in Nitrogen Fixation
			Nitrogen Deposition
		Internal Cycling of Nitrogen
			Overview of Mineralization
			Production and Fate of Dissolved Organic Nitrogen
			Production and Fate of Ammonium
			Production and Fate of Nitrate
			Temporal and Spatial Variability
		Pathways of Nitrogen Loss
			Gaseous Losses of Nitrogen
				Ecological Controls
				Atmospheric Roles of Nitrogen Gases
			Solution Losses
			Erosional Losses
		Other Element Cycles
			Phosphorus
			Sulfur
			Essential Cations
			Micronutrients and Nonessential Elements
		Nitrogen and Phosphorus Cycling in Agricultural Systems
		Summary
		Review Questions
		Additional Reading
	10: Trophic Dynamics
		Introduction
		A Focal Issue
		Overview of Trophic Dynamics
		Controls Over Energy Flow through Ecosystems
			Bottom-Up Controls
			Top-Down Controls
		Trophic Effects on Nutrient Cycling
		Ecological Efficiencies
			Trophic Efficiency and Energy Flow
			Consumption Efficiency
			Assimilation Efficiency
			Production Efficiency
		Food Chain Length
		Seasonal and Interannual Patterns
		Nutrient Transfers
		Detritus-Based Trophic Systems
		Integrated Food Webs
		Summary
		Review Questions
		Additional Reading
	11: Species Effects on Ecosystem Processes
		Introduction
		A Focal Issue
		Overview of Species Effects on Ecosystem Processes
		Effect Functional Types
			Species Effects on Biogeochemistry
				Nutrient Supply
				Nutrient Turnover
			Species Effects on Biophysical Processes
			Species Effects on Trophic Interactions
			Species Effects on Disturbance Regime
		Response Functional Types
		Integrating the Effects of Traits on Ecosystems
			Functional Matrix of Multiple Traits
			Linkages Between Response and Effect Traits
			Diversity as Insurance
			Species Interactions and Ecosystem Processes
		Summary
		Review Questions
		Additional Reading
Part III: Patterns
	12: Temporal Dynamics
		Introduction
		A Focal Issue
		Ecosystem Resilience and Change
			Alternative Stable States
			Resilience and Thresholds
				Sources of Resilience
				Limits to Resilience
				Thresholds and Regime Shifts
		Box 12.1	Resilience and Regime Shifts
		Disturbance
			Conceptual Framework
			Impact of a Disturbance Event
			Recovery and Renewal after Disturbance
			Disturbance Regime
		Succession
			Ecosystem Structure and Composition
				Primary Succession
				Secondary Succession
			Water and Energy Exchange
			Carbon Balance
				Primary Succession
				Secondary Succession
			Nutrient Cycling
				Primary Succession
				Secondary Succession
			Trophic Dynamics
		Temporal Scaling of Ecological Processes
		Summary
		Review Questions
		Additional Reading
	13: Landscape Heterogeneity and Ecosystem Dynamics
		Introduction
		A Focal Issue
		Concepts of Landscape Heterogeneity
		Causes of Spatial Heterogeneity
			Detection and Analysis of Spatial Heterogeneity
			State Factors and Interactive Controls
			Community Processes and Legacies
			Disturbance
			Interactions Among Sources of Heterogeneity
		Patch Interactions on the Landscape
			Topographic and Land–Water Interactions
			Atmospheric Transfers
			Movement of Plants and Animals on the Landscape
			Disturbance Spread
		Human Land-Use Change and Landscape Heterogeneity
			Extensification
			Intensification
		Extrapolation to Larger Scales
		Box 13.1 Spatial Scaling Through Ecological Modeling
		Summary
		Review Questions
		Additional Reading
Part IV: Integration
	14: Changes in the Earth System
		Introduction
		A Focal Issue
		Human Drivers of Change
		The Global Water Cycle
			Water Pools and Fluxes
			Anthropogenic Changes in the Water Cycle
			Consequences of Changes in the Water Cycle
		The Global Carbon Cycle
			Carbon Pools and Fluxes
			Changes in Atmospheric CO 2
			Marine Sinks for CO 2
			Box 14.1 Partitioning of Carbon Uptake Between the Land and Ocean
			Terrestrial Sinks for CO 2
			CO 2 Effects on Climate
			The Global Methane Budget
		The Global Nitrogen Cycle
			Nitrogen Pools and Fluxes
			Anthropogenic Changes in the Nitrogen Cycle
		The Global Phosphorus Cycle
			Phosphorus Pools and Fluxes
			Anthropogenic Changes in the Phosphorus Cycle
		The Global Sulfur Cycle
		Summary
		Review Questions
		Additional Reading
	15: Managing and Sustaining Ecosystems
		Introduction
		A Focal Issue
		Sustaining Social–Ecological Systems
			Box 15.1 Social-Ecological Interactions and the Flooding of New Orleans
			Sustainability
			Ecological Dimensions of Sustainability
		Box 15.2 Assessing Tradeoffs Among Ecosystem Services: Hydropower Versus Conservation in New Zealand
		Box 15.3 Water Purification for New York City
		Conceptual Framework for Ecosystem Management
			Sustaining Soil Resources
			Sustaining Biodiversity
			Sustaining Variability and Resilience
		Applying Ecosystem Principles to Management
			Forest Management
			Fisheries Management
			Ecosystem Renewal
			Box 15.4 Everglades Restoration Study
			Management for Endangered Species
		Socioeconomic Contexts of Ecosystem Management
			Meeting Human Needs and Wants
			Managing Flows of Ecosystem Services
			Addressing Political Realities
			Innovation and Adaptive Management
			Sustainable Development: Social–Ecological Transformation
		Summary
		Review Questions
		Additional Reading
Abbreviations
Glossary
References
Index
                        
Document Text Contents
Page 2

Principles of Terrestrial
Ecosystem Ecology

Page 273

256 8 Plant Nutrient Use

production, and, during herbivore population
outbreaks, herbivores may consume most aboveg-
round production (see Chap. 10). Herbivory has a
much larger impact on plant nutrient budgets than
the biomass losses would suggest because her-
bivory precedes resorption, so vegetation loses
approximately twice as much nitrogen and phos-
phorus per unit biomass to herbivores as it would
through senescence. Animals also generally feed
preferentially on tissues that are rich in nitrogen
and phosphorus, thus maximizing the nutritional
impact of herbivory on plants. There has there-
fore been strong selection for chemical and mor-
phological defenses that deter herbivores and
pathogens. These defenses occur in largest quan-
tities in tissues that are long lived and in environ-
ments where nutrient supply is inadequate to
readily replace nutrients lost to herbivores (Coley
et al. 1985; Gulmon and Mooney 1986; Herms
and Mattson 1992). Most nutrients transferred
from plants to herbivores are rapidly returned
to the soil in feces and urine, where they quickly
become available to plants. In this way, herbivory
accelerates nutrient cycling (see Chap. 10),
especially in ecosystems that are managed for
grazing. Nutrients are susceptible to loss from
the ecosystem in situations where overgrazing
reduces plant biomass to the point that plants
cannot absorb the nutrients returned to the soil by
herbivores.

Other Avenues of Nutrient Loss
from Plants

Other avenues of nutrient loss are poorly
known. Although laboratory studies suggest that
root exudates containing amino acids may be a
significant component of the plant carbon budget
(Rovira 1969), the magnitude of nitrogen loss
from plants by this avenue is unknown. Other
avenues of nutrient loss from plants include plant
parasites such as mistletoe and nutrient transfers
by mycorrhizae from one plant to another.
Although these nutrient transfers may be critical
to the nutrient distribution among species in the
community, they do not greatly alter nutrient
retention or loss by vegetation as a whole.

Disturbances cause occasional large pulses
of nutrient loss from vegetation. Fire, wind,
disease epidemics, and other catastrophic distur-
bances cause massive nutrient losses from vege-
tation when they occur. With the exception of fire
and human harvest, the nutrient loss from vegeta-
tion represents a nutrient transfer from vegetation
to soil rather than a loss from the ecosystem. The
pulse of decomposition and mineralization that
accompanies this large litter input leads to both
rapid nutrient absorption by early successional
vegetation and the potential for leaching losses
from the ecosystem (see Chap. 9). Nutrient losses
from vegetation during wildfire vary with both
the nutrient and fire intensity. Nitrogen and sulfur
volatilize in fires more than do potassium and
phosphorus, for example, whereas calcium and
magnesium are largely transferred in ash.
Nitrogen losses range from nearly 80% in stand-
replacing forest fires to modest in fire-prone
savannas and grasslands, where fires generally
burn during the dry season after senescence and
resorption have occurred and burn more litter
than live plant biomass. Most plant nutrients in
these ecosystems are stored below ground during
times when fires are likely to occur.

Summary

Most of the open ocean is a nutritional desert,
remote from the benthic supply of nutrients and
distant from terrestrial inputs. The dominant pri-
mary producers are single-celled phytoplankton
that reduce nutrient limitation through their
extremely small size and high surface-to-volume
ratio, which speeds nutrient diffusion to the cell
surface. The degree of marine nutrient limitation
reflects a balance between stratification from sur-
face heating and turbulent mixing by winds and
ocean currents. Highly stratified tropical ocean
basins have extremely low nutrient availability
and productivity, whereas turbulent mixing sup-
ports seasonal pulses of productivity in temperate
and high-latitude ocean basins. Most pelagic pro-
duction is co-limited by nitrogen and phosphorus
in the short term. Nitrogen limitation in many
parts of the ocean is amplified by low availability

Page 274

257Review Questions

of iron that limits the activity of nitrogen-fixing
cyanobacteria. The nutrient controls over lake
productivity are similar to those in the ocean,
except that, in the short term, most of the ocean
responds most strongly to nitrogen and olig-
otrophic lakes respond more strongly to phos-
phorus. In the long term, however, phosphorus
may, in many cases, be the ultimate limiting
nutrient to both lakes and the ocean. The produc-
tivity of rivers and streams can be limited by
either nitrogen or phosphorus, depending on the
nature of the terrestrial matrix.

Nutrient availability is a major constraint to
the productivity of the terrestrial biosphere.
Whereas carbon acquisition by plants is deter-
mined primarily by plant traits (leaf area and
photosynthetic capacity), nutrient absorption is
usually governed more strongly by environment
(the rate of supply by the soil) than by plant traits.
In early succession, however, plant traits can
have a significant impact on nutrient absorption
by vegetation at the ecosystem level. Diffusion is
the major process that delivers nutrients from the
bulk soil to the root surface. Mass flow of nutri-
ents in moving soil water is primarily important
in replenishing diffusion shells and in supplying
those nutrients that are abundant in soils or are
required in small amounts by plants.

Plants adjust their capacity to acquire nutri-
ents in several ways. Preferential allocation to
roots under conditions of nutrient limitation max-
imizes the root length available to absorb nutri-
ents. Root growth is concentrated in hot spots of
relatively high nutrient availability, maximizing
the nutrient return for roots that are produced.
Plants further increase their capacity to acquire
nutrients through symbiotic associations with
mycorrhizal fungi. Plants that grow rapidly, due
either to a favorable environment or a high rela-
tive growth rate, have a high capacity to absorb
nutrients. Plants alter the kinetics of nutrient
absorption to absorb those nutrients that most
strongly limit growth. In the case of nitrogen,
which is the most strongly limiting nutrient in
many terrestrial ecosystems, plants typically
absorb whatever forms are available in the soil.
When all forms are equally available, most plants
preferentially absorb ammonium or amino acids

rather than nitrate. Nitrate absorption is often
important, however, because of its high mobility
in soil.

There is an inevitable tradeoff between the
maximum rate of nutrient investment in new
growth and the efficiency with which nutrients
are used to produce biomass. Plants produce bio-
mass most efficiently per unit of nutrient under
nutrient-limiting conditions that constrain pro-
ductivity. Nutrient use efficiency is maximized
by prolonging tissue longevity, that is, by reduc-
ing the rate at which nutrients are lost. Senescence
is the major avenue by which nutrients are lost
from plants. Plants minimize the loss of growth-
limiting nutrients by resorbing about half of the
nitrogen, phosphorus, and potassium from a leaf
before it is shed. About 15% of the annual nutri-
ent return from aboveground plant parts to the
soil comes as leachates, primarily as throughfall
that drips from the canopy. Herbivores can also
be important avenues of nutrient loss because
they feed preferentially on nutrient-rich tissues
and consume these tissues before resorption can
occur. For these reasons, plants lose more than
twice as much nutrients per unit of biomass to
herbivores compared to losses through senes-
cence. Other factors that cause occasional large
nutrient losses from vegetation include distur-
bances (e.g., fire and wind) and diseases that kill
tissues or plants.

Review Questions

1. How do oceanographic controls over stratifi-
cation and mixing influence nutrient absorp-
tion and use in marine phytoplankton?

2. Why do phytoplankton use so little of the
available nitrogen and phosphorus in HNLC
regions of the ocean?

3. Mass flow, diffusion, and root interception
are three processes that deliver nutrients to
the root surface. How does each process
work, and what is their relative importance
in supplying nutrients to plants?

4. What is the major mechanism by which
plants acquire nutrients that reach the root
surface?

Page 545

528 Index

Terrestrial photosynthesis (continued)
leaf life span effect, 143, 144
leaf nitrogen concentration, 142–143
shade-tolerant and shade-intolerant species, 143
SLA, 144–145

open stomata, 136
photosynthetic cells, 134
pollutants, 147–148
Rubisco, 135
stomatal conductance, 136
temperature effects, 147
water limitation, 145–146
water turbulence, 134

Thermocline, 35, 164
Thermohaline circulation, 36–37
Thermosphere, 29
Thresholds, 341–342

regime shifts
assisted migration, 346
cheatgrass invasion, 343
Pan balance model, 345
perturbations, 344
phosphorus saturation, 343, 345
restoration ecology, 346

Throughfall, 102, 255
Thylakoids, 126
Tilt, 41
Time step, 393
Top-down controls, 305–306
Topography

soil formation, 66–67
soil loss, 15

Toposequence, 15
Tradeoffs, 143–144, 425–426, 430
Trade winds, 32, 33
Transfer zone, 70–71
Transpiration, 93
Trophic cascade, 305, 316
Trophic dynamics

assimilation efficiency, 312–313
consumption efficiency

activity budgets, 311
atmospheric CO

2
concentration, 311

ecosystem changes, 298, 310
grazing lawns, 310
gypsy moths and snowshoe hares, 312
herbivor trophic level, 310
homeothermy, 312
nematodes, 310
poikilothermic animals, 311
secondary metabolites, 312

detritus-based trophic systems, 298, 317–318
domestic livestock, 297, 298
energy flow controls

allochthonous, 301
biochemical processes, 304
carbon-based defense, 302
defense growth, 302, 303
eutrophication, 305
herbivore consumption, 302

natural and managed grasslands, 300, 301
net primary production, 300, 301
nitrogen-based defenses, 303
oligotrophic, 300
plant allocation, 302–304
plant-based and detritus-based webs, 300
stoichiometric relationships, 304
subsidies, 300
sulfur-containing defenses, 303
trophic cascades, 305–306
trophic levels, 305

food chain, 299, 314
food webs, 299
heterotrophs, 298
human population, 297, 298
integrated food webs, 318
nutrient cycling effects, 298, 301, 306–307
nutrient transfers, 297, 315–316
palatable plants, 297
phosphorus concentrations, 300
primary detritivores, 299
primary producers/autotrophs, 298
primary productivity and herbivory, 297, 298
production efficiency, 313
seasonal and interannual patterns, 314–315
trophic efficiency and energy flow

animal production, 307, 308
biomass distribution, 308
biomass pyramid, 307, 309
energy pyramid, 307, 308, 309

trophic transfers, 298
Trophic efficiency, 307–308
Trophic interactions, 8, 328–329
Trophic level, 299, 307–308
Trophic transfer, 298
Tropical forests, 12, 107, 143, 169–171, 177–180
Tropopause, 29
Troposphere, 28–29
Tundra, 58, 171, 172, 174, 177, 178, 302.

See also Arctic tundra
Turbulence, 25, 98

convective, 98
mechanical, 98

Turbulent mixing, 115, 116
Turnover length, 221, 265
Turnover time, 404

U
Ultimate limiting nutrient, 233
Uplift, plates of Earth, 65–66
Upwelling, 36, 263
Urease, 273
Utisols, 82

V
Vapor pressure deficit (VPD), 100
Vegetation

albedo, 40

Page 546

529Index

chemical weathering, 74
desert, 57
evapotranspiration, 40
NDVI, 153
soil formation, 67, 70

Vertisols, 81
Vesicular arbuscular mycorrhizae (VAM), 243
Voids, 83
Volcanic eruptions. See Disturbances to ecosystem

W
Water balance

budgets
blue water, 101
closed-basin lakes, 101
green water, 101
inputs and outputs, 100
precipitation, 100

evapotranspiration, 93
inputs

canopy interception, 102
phreatophytes, 101
precipitation, 101

land-use changes, 93–94
losses

changes in storage, 118–119
evaporation from dry canopies, 115–117
evaporation from wet canopies, 115
runoff, 119–120

surface energy balance
(see Surface energy balance)

water movements (see Water movements)
water vapor feedback, 94

Water cycle
anthropogenic changes, 405
irrigation, 405, 406
pools and fluxes

fossil groundwater, 405
turnover time, 404

Water-holding capacity, 85
Water losses

changes in storage, 118–119
evaporation from dry canopies, 115–117

aerodynamic conductance, 115
decoupling coefficient, 116
diffusion, 115
evapotranspiration, 117
turbulent mixing, 115, 116
vegetation structure, 116

evaporation from wet canopies, 115
runoff, 119–120

Water movements
canopy interception

dry and wet grass, 103
Eucalyptus species, 102, 103

soil to roots
root hairs and mycorrhizal hyphae, 106
rooting depth, 106, 107
water potential, 105–106

storage
energy status, 104
field capacity, 105
hydraulic conductivity, 104
infiltration, 104–105
permanent wilting point, 105
pressure potential, 104
soil water, 104
water potential, 104

through plants
leaves (see Leaves, water movement)
roots (see Roots, water movement)
stems (see Stems, water movement)
vapor-pressure gradient, 106
water-pressure gradient, 107

Water potential, 85, 104–106
Water residence time, 264–265
Water-saturated, 85
Watershed. See Drainage basin
Water use efficiency (WUE), 146
Water vapor feedback, 94
Weathering. See also Rock weathering

allophane, 76
CEC, 75
chemical, 74
clay particles, 75
crystalline, 76
minerals, 74–75
physical, 74
physical and chemical properties, rock, 74

Westerlies and Polar Biomes, 33, 234
Western Polynesia, 331
Wet forests, 56
White-rot fungi, 186–187
Wind-flow patterns, 33–34

X
Xanthophyll cycle, 127

Z
Zebra mussels, 429
Zooplankton, 222

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