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- **19.1** A Variety of Processes Gives Rise to Landscape Patterns
- **19.2** Landscape Pattern Is Defined by the Spatial Arrangement and Connectivity of Patches
- 19.3 Boundaries Are Transition Zones that Offer Diverse Conditions and Habitats
- **19.4** Patch Size and Shape Influence Community Structure
- 19.5 Landsca... | {
"Header 1": "ECOLOGICAL Issues & Applications",
"Header 3": "**CHAPTER GUIDE**",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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When we view a landscape we notice the composition, that is, the types of land cover or communities (patches) and their spatial arrangement (as in Figure 19.1). How does the mosaic of patches develop on the landscape? The spatial structure of each landscape is unique and results from the interactions of a variety of fa... | {
"Header 1": "19.1 A Variety of Processes Gives Rise to Landscape Patterns",
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A landscape is a spatially heterogeneous area, a mosaic of elements referred to as patches. **Patches** are areas that are more or less homogeneous compared to their surroundings.
Figure 19.6 Examples of landscape patterns created by human land use. (a) Block clear-cutting in a coniferous forest in the western United... | {
"Header 1": "19.2 Landscape Pattern Is Defined by the Spatial Arrangement and Connectivity of Patches",
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The place where the edge of one patch meets the edge of another is called a boundary, which is an area of contact, separation, or transition between patches. Some boundaries
Figure 19.9 Example of defining landscape based on the organism or process being examined. (a) For the meadow vole (*Microtus pennsylvanicus*), ... | {
"Header 1": "19.3 Boundaries Are Transition Zones that Offer Diverse Conditions and Habitats",
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*Q1. How does air temperature (top graph) change as you move out of an oak woodland patch into a surrounding chaparral habitat?*
*Q2. In general, how does relative humidity (bottom graph) change as you move out of an oak woodland patch into a surrounding chaparral habitat?*
*Q3. Why are the observed changes in rela... | {
"Header 1": "19.3 Boundaries Are Transition Zones that Offer Diverse Conditions and Habitats",
"Header 3": "*Interpreting Ecological Data*",
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Patch size has a crucial influence on community structure, species diversity, and the presence and absence of species. As a general rule, large patches of habitat contain a greater number of individuals (population size) and species (species richness) than do small patches. The increase in population size for a given s... | {
"Header 1": "19.4 Patch Size and Shape Influence Community Structure",
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It is the type, number, and spatial arrangement of patches on the landscape that influence movement of organisms among patches, and ultimately the population dynamics of species and community structure. The degree to which the landscape facilitates or impedes the movement of organisms among patches is referred to as **... | {
"Header 1": "19.5 Landscape Connectivity Permits Movement between Patches",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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But in this experiment, the length of the corridor was
**Figure 1** Map of experimental landscape locations and aerial photograph of one landscape, showing patch configuration.
Figure 2 Movement rates of butterfly species between connected and isolated ... | {
"Header 1": "19.5 Landscape Connectivity Permits Movement between Patches",
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As we have seen in the preceding sections, the community structure of a patch on the landscape is a function of its size, shape, and connectivity (position on the landscape relative to other patches). Yet how do these characteristics interact to determine community structure? The theory of island biogeography, first de... | {
"Header 1": "19.6 The Theory of Island Biogeography Applies to Landscape Patches",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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In contrast to island biogeography, which examines the species richness of a single habitat patch as a function of the colonization by new species and local extinction of current resident species, metapopulation theory examines the colonization and local extinction of local populations of a given species on the array o... | {
"Header 1": "19.7 Metapopulation Theory Is a Central Concept in the Study of Landscape Dynamics",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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I n 1970, Richard Levins proposed a simple model of metapopulation dynamics in which metapopulation size is defined by the fraction of (discrete) habitat patches (*P*) occupied at any given time (*t*). Within a given time interval, each subpopulation occupying a habitat patch has a probability of going extinct (*e*). T... | {
"Header 1": "19.7 Metapopulation Theory Is a Central Concept in the Study of Landscape Dynamics",
"Header 3": "Quantifying Ecology 19.1 Model of Metapopulation Dynamics",
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The researchers found a significant positive relationship between patch size and local population size (Figure 19.28). Data revealed that the risk of local extinction increases for a patch size of less than one-half ha (see Figure 19.27d), which corresponds to a critical population size of about 12 males (see Chapter 1... | {
"Header 1": "19.7 Metapopulation Theory Is a Central Concept in the Study of Landscape Dynamics",
"Header 3": "Quantifying Ecology 19.1 Model of Metapopulation Dynamics",
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Some researchers have extended the framework of metapopulations to examine the dynamics involving interactions among local communities. Each habitat patch on the landscape is composed of a set of species that define the local community. The set of local communities (sets of species that interact with one another), occu... | {
"Header 1": "19.8 Local Communities Occupying Patches on the Landscape Define the Metacommunity",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Unlike the artist's mosaic shown in Figure 19.2 with its fixed pattern, the mosaic of communities defining the landscape is ever changing. Disturbances—large and small, frequent and infrequent—alter the biological and physical structures of communities making up the landscape, giving way to the
![](_page_449_Figure_1... | {
"Header 1": "19.9 The Landscape Represents a Shifting Mosaic of Changing Communities",
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Given the ever-growing pressures placed on lands by the human population, and fragmentation of existing habitats, preservation of biological diversity depends more and more on the establishment of designated protected areas. According to the International Union for the Conservation of Nature (IUCN) there are currently ... | {
"Header 1": "Corridors Are Playing a Growing Role in Conservation Efforts",
"token_count": 1995,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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#### Creating Landscapes 19.1
A variety of factors give rise to landscapes including abiotic, biotic, natural disturbances, and human activities. Climate and geology interact to define the land. Abiotic and biotic factors interact to determine species composition. Disturbance, a discrete event that disrupts communiti... | {
"Header 1": "Corridors Are Playing a Growing Role in Conservation Efforts",
"Header 3": "S ummary",
"token_count": 2053,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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T. A. Pickett, K. E. Weathers, and C. D. Jones. 2003. "A framework for a theory of ecological boundaries." *BioScience* 53:750–758. This article provides a framework for the study of ecological boundaries, focusing on flows of organisms, materials, and
- Collinge, S. K. 2009. *Ecology of fragmented landscapes.* Balti... | {
"Header 1": "Corridors Are Playing a Growing Role in Conservation Efforts",
"Header 3": "S ummary",
"token_count": 699,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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- 20.1 The Laws of Thermodynamics Govern Energy Flow
- 20.2 Energy Fixed in the Process of Photosynthesis Is Primary Production
- 20.3 Climate and Nutrient Availability Are the Primary Controls on Net Primary Productivity in Terrestrial Ecosystems
- 20.4 Light and Nutrient Availability Are the Primary Controls on Net P... | {
"Header 1": "Corridors Are Playing a Growing Role in Conservation Efforts",
"Header 3": "Chapter Guide",
"token_count": 515,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Energy exists in two forms: potential and kinetic. **Potential energy** is stored energy; it is capable of and available for performing work. **Kinetic energy** is energy in motion. It performs work at the expense of potential energy. Work occurs when a force acts on an object causing its displacement.
Two laws of th... | {
"Header 1": "**20.1** The Laws of Thermodynamics Govern Energy Flow",
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The rate at which carbon dioxide in the atmosphere or water is converted into organic compounds by autotrophs is referred to as *primary productivity* because it is the first and basic form of energy storage in ecosystems. With the limited exception of chemotrophs (see Sections 6.1 and 24.11 for discussion of chemotrop... | {
"Header 1": "**21.2** Energy Fixed in the Process of Photosynthesis Is Primary Production",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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An array of environmental factors, including climate, influence the productivity of terrestrial ecosystems. Measured estimates of NPP for various terrestrial ecosystems around the
**Figure 20.1** Paired light and dark bottles are used to measure photosynthesis (gross production), respi... | {
"Header 1": "20.3 Climate and Nutrient Availability Are the Primary Controls on Net Primary Productivity in Terrestrial Ecosystems",
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(NASA/MODIS.)
Table 20.1 Net Primary Productivity and Plant Biomass of World Ecosystems
| Ecosystems (in order<br>of productivity) | Area<br>(106km2) | Mean Net Primary<br>Productivity per<br>Unit Area<br>(g/m2/yr) | World Net Primary<br>Productivity<br>(109 Mt/yr) | Mean Biomass<br>per Unit Area<br>(kg/m2) | Relat... | {
"Header 1": "20.3 Climate and Nutrient Availability Are the Primary Controls on Net Primary Productivity in Terrestrial Ecosystems",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Light is a primary factor limiting productivity in aquatic ecosystems, and the depth to which light penetrates a lake or ocean is crucial in determining the zone of primary productivity. Recall that photosynthetically active radiation (PAR) declines exponentially with water depth (Figure 20.8, see also Figure 3.7). The... | {
"Header 1": "20.4 Light and Nutrient Availability Are the Primary Controls on Net Primary Productivity in Aquatic Ecosystems",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Organic carbon produced within an ecosystem is described as **autochthonous**, whereas inputs from outside the ecosystem are described as **allochthonous**. In aquatic ecosystems, the autochthonous input is provided through photosynthesis by aquatic plants, attached algae in shallow waters, and by phytoplankton in the ... | {
"Header 1": "20.5 External Inputs of Organic Carbon Can Be Important to Aquatic Ecosystems",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Previously, we examined the implications of how plants allocate the carbon fixed in photosynthesis (carbon allocation) to the process of plant growth (see Chapter 6, Quantifying
**Ecology 6.1**). You will recall that the process of plant growth functions as a positive feedback system. For a given rate of photosynthes... | {
"Header 1": "20.6 Energy Allocation and Plant Life-Form Influence Primary Production",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Primary production also varies within an ecosystem with time and age (**Figure 20.15**). Both photosynthesis and plant growth are directly influenced by seasonal variations in environmental conditions (Figure 20.15a). Regions with cold winters or distinct wet and dry seasons have a period of plant dormancy when primary... | {
"Header 1": "**20.7** Primary Production Varies with Time",
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Net primary production is the energy available to the heterotrophic component of the ecosystem. Either herbivores or decomposers eventually consume virtually all primary productivity, but often it is not all used within the same ecosystem. Humans or other agents, such as wind or water currents, may disperse the NPP of ... | {
"Header 1": "**20.8** Primary Productivity Limits Secondary Production",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Although there is a general relationship between the availability of primary productivity and the productivity of consumer organisms (secondary productivity) across a variety of terrestrial and aquatic ecosystems, within a given ecosystem there is considerable variation among consumer organisms in their efficiency in t... | {
"Header 1": "20.9 Consumers Vary in Efficiency of Production",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Organic compounds fixed by autotrophs are the source of energy on which the rest of life on Earth depends. This energy stored by autotrophs is passed along through the ecosystem in a series of steps of eating and being eaten—known as a *food chain* (see Section 16.5). Feeding relationships within a food chain are defin... | {
"Header 1": "20.10 Ecosystems Have Two Major Food Chains",
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To establish the role of predators in determining the distribution of snails within the marsh, Silliman once again used wire mesh cages—this time not to exclude the snails, but to exclude their predators. Other plots (areas of marsh) without cages were monitored for comparison (control plots). The experiment ran for ... | {
"Header 1": "20.10 Ecosystems Have Two Major Food Chains",
"token_count": 1379,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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To quantify the flux of energy through the ecosystem using the conceptual model of the food chains just discussed, we need to return to the processes involved in secondary production discussed in Section 20.9: consumption, ingestion, assimilation, respiration, and production. We will examine a single trophic compartmen... | {
"Header 1": "20.11 Energy Flows through Trophic Levels Can Be Quantified",
"token_count": 541,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Although the general model of energy flow presented in Figure 20.23 pertains to all ecosystems, the relative importance of the two major food chains and the rate of energy flow
through the various trophic levels can vary widely among different types of ecosystems. The consumption effici... | {
"Header 1": "20.12 Consumption Efficiency Determines the Pathway of Energy Flow through the Ecosystem",
"token_count": 884,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Based on the preceding discussion and the analysis presented in Figure 20.24, we can conclude that the quantity of energy flowing into a trophic level decreases with each successive trophic level in the food chain. This pattern occurs because not all energy is used for production. An ecological rule of thumb is that on... | {
"Header 1": "**20.13** Energy Decreases in Each Successive Trophic Level",
"token_count": 923,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Although we represent only 1 of more than 1.4 million known species inhabiting our planet, humans use a vastly disproportionate share of Earth's resources. This pattern of resource use is most evident in the human appropriation of NPP. The basic question of how much of Earth's primary productivity is used by humans was... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "Humans Appropriate a Disproportionate Amount of Earth's Net Primary Productivity",
"token_count": 1110,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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errestrial ecologists use a variety of techniques to estimate net primary productivity (NPP) at a site. Methods range from clipping sample plots in grasslands to estimating seasonal grass production, measuring the diameter growth of individual trees within a forest stand, to continually measuring the exchange of carbon... | {
"Header 1": "Estimating Net Primary Productivity Using Satellite Data",
"token_count": 2039,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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As energy moves through an ecosystem, much of it is lost as heat of respiration. Energy degrades from a more organized to a less organized state (entropy). However, a continuous flux of energy from the Sun prevents ecosystems from running down.
#### Primary Production 20.2
The flow of energy through an ecosystem st... | {
"Header 1": "Estimating Net Primary Productivity Using Satellite Data",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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*A history of the ecosystem concept in ecology.* New Haven, CT: Yale University Press. This book presents a historical overview of the development of the study of ecosystems in the broader framework of ecology.
Howarth, R. W. 1988. "Nutrient limitation of net primary production in marine ecosystems." *Annual Review o... | {
"Header 1": "Estimating Net Primary Productivity Using Satellite Data",
"token_count": 208,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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- **21.1** Most Essential Nutrients Are Recycled within the Ecosystem
- **21.2** Decomposition Is a Complex Process Involving a Variety of Organisms
- 21.3 Studying Decomposition Involves Following the Fate of Dead Organic Matter
- **21.4** Several Factors Influence the Rate of Decomposition
- **21.5** Nutrients in Org... | {
"Header 1": "Estimating Net Primary Productivity Using Satellite Data",
"Header 3": "**CHAPTER GUIDE**",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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The cycling of nutrients within a terrestrial ecosystem is represented in **Figure 21.1**. We use the essential element nitrogen as an example to follow the pathway taken by nutrients from the soil to the vegetation and back again to the soil.
As with all essential nutrients, plants require nitrogen in an inorganic o... | {
"Header 1": "**21.1** Most Essential Nutrients Are Recycled within the Ecosystem",
"token_count": 598,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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The key process in the recycling of nutrients within ecosystems is decomposition. Decomposition is the breakdown of chemical bonds formed during the construction of plant and animal tissues. Whereas photosynthesis involves the incorporation of solar energy, carbon dioxide, water, and inorganic nutrients into organic co... | {
"Header 1": "21.2 Decomposition Is a Complex Process Involving a Variety of Organisms",
"token_count": 1430,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Decomposers, like all heterotrophs, derive the energy and most of the nutrients they require by consuming organic compounds. Energy is obtained through the oxidation of carbon compounds—carbohydrates (such as glucose)—in the process of respiration (see Section 6.1). Ecologists study the process of decomposition by desi... | {
"Header 1": "21.3 Studying Decomposition Involves Following the Fate of Dead Organic Matter",
"token_count": 863,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
itterbag experiments such as the ones presented in Figures 21.4 and 21.6 are the primary means by which ecologists study the process of decomposition. By collecting multiple (replicate) litterbags at regular intervals during the process of decay, researchers can plot the proportion of mass loss (or proportion of mass r... | {
"Header 1": "21.3 Studying Decomposition Involves Following the Fate of Dead Organic Matter",
"Header 3": "QUANTIFYING ECOLOGY 21.1 Estimating the Rate of Decomposition",
"token_count": 1747,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Not all organic matter decomposes at the same rate. For example, note the differences in decomposition rate for the leaf litter of the three tree species reported in Figure 21.4. From the wealth of studies completed over the past 50 years, some generalizations concerning factors that influence decomposition rate have e... | {
"Header 1": "21.4 Several Factors Influence the Rate of Decomposition",
"token_count": 2040,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Just as dead organic matter varies in the quality of carbon compounds as an energy source for microbial decomposers, likewise the nutrient quality of dead organic material varies greatly. The macronutrient nitrogen can serve as an example. Most dead leaf material has a nitrogen content in the range of 0.5–1.5 percent (... | {
"Header 1": "21.5 Nutrients in Organic Matter Are Mineralized During Decomposition",
"token_count": 2046,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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The lower phosphorus availability results in a slower turnover rate of carbon (decomposition rate), resulting in an indirect control of precipitation on the processes of decomposition and nutrient cycling in these lowland tropical forests through the direct effect on litter quality.
#### Bibliography
Schuur, E. A. ... | {
"Header 1": "21.5 Nutrients in Organic Matter Are Mineralized During Decomposition",
"token_count": 1379,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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We have thus far discussed a process of decomposition in which decomposer organisms consume plant litter. In doing so, they mineralize nutrients and alter the chemical composition of residual organic matter. This process continues as the litter degrades into a dark brown or black homogeneous organic matter known as *hu... | {
"Header 1": "21.6 Decomposition Proceeds as Plant Litter Is Converted into Soil Organic Matter",
"token_count": 1313,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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More than a century ago, the soil scientist Lorenz Hiltner put forward the term **rhizosphere** to describe a region of the soil where plant roots function. It is an active zone of root growth and death, characterized by intense microbial and fungal activity. Decomposition in the rhizosphere is more rapid than in the s... | {
"Header 1": "21.7 Plant Processes Enhance the Decomposition of Soil Organic Matter in the Rhizosphere",
"token_count": 783,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Decomposition in aquatic ecosystems follows a pattern similar to that in terrestrial ecosystems but with some major differences influenced by the watery environment. As in terrestrial environments, decomposition involves leaching, fragmentation, colonization of detrital particles by bacteria and fungi, and consumption ... | {
"Header 1": "21.8 Decomposition Occurs in Aquatic Environments",
"token_count": 1025,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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You can see from Figure 21.1 that the internal cycling of nutrients through the ecosystem depends on the processes of primary production and decomposition. Primary productivity determines the rate of nutrient transfer from inorganic to organic form (nutrient uptake), and decomposition determines the rate of transformat... | {
"Header 1": "21.9 Key Ecosystem Processes Influence the Rate of Nutrient Cycling",
"token_count": 912,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Nutrient cycling is an essential process in all ecosystems and represents a direct (cyclic) link between NPP and decomposition. However, the nature of this link varies among ecosystems, particularly between terrestrial and aquatic ecosystems.
In virtually all ecosystems, there is a vertical separation between the zon... | {
"Header 1": "21.10 Nutrient Cycling Differs between Terrestrial and Open-Water Aquatic Ecosystems",
"token_count": 1318,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Inputs in the form of dead organic matter from adjacent terrestrial ecosystems (leaves and woody debris), rainwater, and subsurface seepage bring nutrients into streams. Although the internal cycling of nutrients follows the same general pathway as that discussed for terrestrial and open-water ecosystems (see Figure 21... | {
"Header 1": "21.11 Water Flow Influences Nutrient Cycling in Streams and Rivers",
"token_count": 735,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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Coastal ecosystems are among the most productive environments. Water from most streams and rivers eventually drains into the oceans, and the place where this freshwater joins saltwater is called an *estuary* (see Section 3.10). Estuaries are semi-enclosed parts of the coastal ocean where seawater is diluted and partial... | {
"Header 1": "21.12 Land and Marine Environments Influence Nutrient Cycling in Coastal Ecosystems",
"token_count": 1142,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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The global pattern of ocean surface currents influences patterns of surface-water temperature, productivity, and nutrient cycling (Chapter 2, Figure 2.13). The Coriolis effect drives the patterns of surface currents. But how deep does this lateral movement of water extend vertically into the water column? In general, t... | {
"Header 1": "21.13 Surface Ocean Currents Bring about Vertical Transport of Nutrients",
"token_count": 289,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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As we discussed in Section 21.9 (Figure 21.20), in natural ecosystems there is a tight link between the processes of NPP and decomposition. NPP determines the quantity and quality of organic matter available to decomposer populations. In turn, the process of decomposition determines the rate of nutrient release to the ... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "Agriculture Disrupts the Process of Nutrient Cycling",
"token_count": 1872,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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As the world population increased, the growing demand for food was accompanied by an increasing need for fertilizers, and by the late 1800s there was growing concern about depletion of the limited sources of nitrogen used as mineral fertilizer
Table 21.2 Sample of Typical C:N for a Variety of Organic Materials (Inclu... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "Agriculture Disrupts the Process of Nutrient Cycling",
"token_count": 2031,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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#### Stream Ecosystems 21.11
The continuous, directional movement of water affects nutrient cycling in stream ecosystems. Because nutrients are continuously being transported downstream, a spiral rather than a cycle better represents the cycling of nutrients. One cycle in the spiral is the uptake of an atom of nutr... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "Agriculture Disrupts the Process of Nutrient Cycling",
"token_count": 1730,
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- 22.1 There Are Two Major Types of Biogeochemical Cycles
- 22.2 Nutrients Enter the Ecosystem via Inputs
- 22.3 Outputs Represent a Loss of Nutrients from the Ecosystem
- 22.4 Biogeochemical Cycles Can Be Viewed from a Global Perspective
- 22.5 The Carbon Cycle Is Closely Tied to Energy Flow
- 22.6 Carbon Cycling Vari... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "CHAPTER GUIDE",
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"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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There are two basic types of biogeochemical cycles: gaseous and sedimentary. This classification is based on the primary source of nutrient input into the ecosystem. In gaseous cycles, the main pools of nutrients are the atmosphere and the oceans. For this reason, gaseous cycles are distinctly global. The gases most im... | {
"Header 1": "**22.1** There Are Two Major Types of Biogeochemical Cycles",
"token_count": 588,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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The input of nutrients to the ecosystem depends on the type of biogeochemical cycle. Nutrients with a gaseous cycle, such as carbon and nitrogen, enter the ecosystem via the atmosphere. In contrast, nutrients such as calcium and phosphorus have sedimentary cycles, with inputs dependent on the weathering of rocks and mi... | {
"Header 1": "**22.2** Nutrients Enter the Ecosystem via Inputs",
"token_count": 366,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
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The export of nutrients from the ecosystem represents a loss that must be offset by inputs if a net decline is not to occur. Export can occur in a variety of ways, depending on the specific biogeochemical cycle. Carbon is exported to the atmosphere in the form of carbon dioxide via the process of respiration by all liv... | {
"Header 1": "22.3 Outputs Represent a Loss of Nutrients from the Ecosystem",
"token_count": 651,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The cycling of nutrients and energy occurs within all ecosystems, and it is most often studied as a local process, that is, the internal cycling of nutrients within the ecosystem and the identification of exchanges both to (inputs) and from (outputs) the ecosystem. Through these processes of exchange, the biogeochemica... | {
"Header 1": "22.4 Biogeochemical Cycles Can Be Viewed from a Global Perspective",
"token_count": 225,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Carbon, a basic constituent of all organic compounds, is involved in the fixation of energy by photosynthesis (see Chapter 6). Carbon is so closely tied to energy flow that the two are inseparable. In fact, we often express ecosystem productivity in terms of grams (g) of carbon fixed per square meter per year (see Sect... | {
"Header 1": "22.5 The Carbon Cycle Is Closely Tied to Energy Flow",
"token_count": 705,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
If you were to measure the concentration of carbon dioxide in the atmosphere above and within a forest on a summer day, you would discover that it fluctuates throughout the day (Figure 22.3). At daylight when photosynthesis begins, plants start to withdraw carbon dioxide from the air, and the concentration declines sha... | {
"Header 1": "**22.6** Carbon Cycling Varies Daily and Seasonally",
"token_count": 526,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The carbon budget of Earth is closely linked to the atmosphere, land, and oceans and to the mass movements of air around the planet (see Chapter 2). Earth contains about 10<sup>23</sup> g of carbon, or 100 million gigaton (Gt) (Gt is a gigaton, equal to 1 billion [10<sup>9</sup>] metric tons, or 10<sup>15</sup> g). All... | {
"Header 1": "**22.7** The Global Carbon Cycle Involves Exchanges among the Atmosphere, Oceans, and Land",
"token_count": 984,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Nitrogen is an essential constituent of protein, which is a building block of all living tissue. Nitrogen is generally available to plants in only two chemical forms: ammonium $(NH_4^+)$ and nitrate $(NO_3^-)$ . Thus, although Earth's atmosphere is almost 80 percent nitrogen gas, it is in a form $(N_2)$ that is no... | {
"Header 1": "**22.8** The Nitrogen Cycle Begins with Fixing Atmospheric Nitrogen",
"token_count": 2004,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Phosphorus occurs in only minute amounts in the atmosphere. Therefore, the phosphorus cycle can follow the water (hydrological) cycle only part of the way—from land to sea (Figure 22.9). Because phosphorus lost from the ecosystem in this way is not returned via the biogeochemical cycle, phosphorus is in short supply un... | {
"Header 1": "**22.9** The Phosphorus Cycle Has No Atmospheric Pool",
"token_count": 890,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The sulfur cycle has both sedimentary and gaseous phases (Figure 22.11). In the long-term sedimentary phase, sulfur is tied up in organic and inorganic deposits, released by weathering and decomposition, and carried to terrestrial ecosystems
in salt solution. The gaseous phase of the cy... | {
"Header 1": "**22.10** The Sulfur Cycle Is Both Sedimentary and Gaseous",
"token_count": 649,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The global sulfur cycle is presented in Figure 22.12. Although a great deal of research now focuses on the sulfur cycle—particularly the role of human inputs—our understanding of the global sulfur cycle is primitive.
The gaseous phase of the sulfur cycle permits circulation on a global scale. The annual flux of sulfu... | {
"Header 1": "22.11 The Global Sulfur Cycle Is Poorly Understood",
"token_count": 579,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The major source of free oxygen that supports life is the atmosphere. There are two significant sources of atmospheric oxygen. One is the breakup of water vapor through a process driven by sunlight. In this reaction, the water molecules (H<sub>2</sub>O) are disassociated to produce hydrogen and oxygen. Most of the hydr... | {
"Header 1": "**22.12** The Oxygen Cycle Is Largely under Biological Control",
"token_count": 990,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Although we have introduced each of the major biogeochemical cycles independently, they are all linked in various ways. In specific cases, they are linked through their common membership in compounds that form an important component of their cycles. Examples are the links between calcium and phosphorus in the mineral a... | {
"Header 1": "22.13 The Various Biogeochemical Cycles Are Linked",
"token_count": 652,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Net primary productivity in most terrestrial forest ecosystems is limited by the availability of soil nitrogen, yet in recent decades, human activities have caused a dramatic increase in the rates of nitrogen deposition. In North America, anthropogenic activities such as fossil fuel combustion and high-intensity agricu... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "Nitrogen Deposition from Human Activities Can Result in Nitrogen Saturation",
"token_count": 1573,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
#### Biogeochemical Cycles 22.1
Nutrients flow from the living to the nonliving components of the ecosystem and back in a perpetual cycle. Through these cycles, plants and animals obtain nutrients necessary for their survival and growth. There are two basic types of biogeochemical cycles: the gaseous, represented by ... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "S um mary",
"token_count": 1809,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
#### S tudy Q uestions
- **1.** What are the three most important gases for life in the atmosphere?
- **2.** (a) How does the rain falling in a forest area differ from that falling in an open area in terms of its nutrient quality? (b) Explain how water is important for biogeochemical cycles.
- **3.** Characterize t... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "S um mary",
"token_count": 2036,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Given that the broad classification of terrestrial biomes presented in Figures 23.1 and 23.2 (forest, woodland/savanna, shrubland, and grassland) reflects the relative contribution of three general plant life-forms (trees, shrubs, and grasses), the question of what controls the distribution of biomes relative to climat... | {
"Header 1": "23.1 Terrestrial Ecosystems Reflect Adaptations of the Dominant Plant Life-Forms",
"token_count": 1850,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The tropical rain forests are restricted primarily to the equatorial zone between latitudes 10° N and 10° S (**Figure 23.5**), where the temperatures are warm throughout the year and rainfall occurs almost daily. The largest and most continuous region of rain forest in the world is in the Amazon basin of South America ... | {
"Header 1": "**23.2** Tropical Forests Characterize the Equatorial Zone",
"token_count": 229,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
A sillustrated in Figure 23.2, the distribution of terrestrial biomes is closely related to climate. The measures of regional climate used in Whittaker's graph (Figure 23.2) are mean annual temperature and precipitation. Yet, as we will see in the discussion of the various biome types, the distribution of terrestrial e... | {
"Header 1": "**23.2** Tropical Forests Characterize the Equatorial Zone",
"Header 3": "QUANTIFYING ECOLOGY 23.1 Climate Diagrams",
"token_count": 1722,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The term *savanna* was originally used to describe the treeless areas of South America. Now it is generally applied to a range of vegetation types in the drier tropics and subtropics characterized by a ground cover of grasses with scattered shrubs or trees. Savanna includes an array of vegetation types representing a c... | {
"Header 1": "23.3 Tropical Savannas Are Characteristic of Semiarid Regions with Seasonal Rainfall",
"token_count": 1184,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Natural grasslands occupy regions where rainfall is between 25 and 80 centimeters (cm) a year, but they are not exclusively climatic. Many exist through the intervention of fire and human activity. Conversions of forests into agricultural lands and the planting of hay and pasturelands extended grasslands into once fore... | {
"Header 1": "23.4 Grassland Ecosystems of the Temperate Zone Vary with Climate and Geography",
"token_count": 2040,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The arid regions of the world occupy from 25 to 35 percent of Earth's landmass (**Figure 23.19**). The wide range reflects the various approaches used to define desert ecosystems based on climate conditions and vegetation types. Much of this land lies between $15^{\circ}$ and $30^{\circ}$ latitude, where the air th... | {
"Header 1": "**23.5** Deserts Represent a Diverse Group of Ecosystems",
"token_count": 2030,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Shrublands—plant communities where the shrub growth form is either dominant or codominant—are difficult types of ecosystems to categorize, largely because of the difficulty in characterizing the term shrub itself. In general, a shrub is a plant with multiple woody, persistent stems but no central trunk and a height fro... | {
"Header 1": "23.6 Mediterranean Climates Support Temperate Shrublands",
"token_count": 1763,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Climatic conditions in the humid midlatitude regions give rise to the development of forests dominated by broadleaf deciduous trees (Figure 23.27). But in the mild, moist climates of
Figure 23.26 Chaparral is the dominant mediterranean shrub vegetation... | {
"Header 1": "23.7 Forest Ecosystems Dominate the Wetter Regions of the Temperate Zone",
"token_count": 1368,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Conifer forests, dominated by needle-leaf evergreen trees, are found primarily in a broad circumpolar belt across the Northern Hemisphere and on mountain ranges, where low temperatures limit the growing season to a few months each year (Figure 23.30). The variable composition and structure of these forests reflect the ... | {
"Header 1": "23.8 Conifer Forests Dominate the Cool Temperate and Boreal Zones",
"token_count": 1717,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Encircling the top of the Northern Hemisphere is a frozen plain, clothed in sedges, heaths, and willows, dotted with lakes, and crossed by streams (Figure 23.34). Called *tundra*, its name comes from the Finnish *tunturi*, meaning "a treeless plain." The arctic tundra falls into two broad types: tundra with up to 100 p... | {
"Header 1": "23.9 Low Precipitation and Cold Temperatures Define the Arctic Tundra",
"token_count": 1738,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Figure 23.38 A variety of products derived from forests.
Forest ecosystems cover approximately 35 percent of Earth's surface and provide a wealth of resources, including fuel, building materials, and food (Figure 23.38). Although plantations provide a growing percentage of forest resour... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "The Extraction of Resources from Forest Ecosystems Involves an Array of Management Practices",
"token_count": 2038,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Note the large increase in concentrations of nitrate in the stream on the clear-cut watershed. This increase is a result of increased decomposition and nitrogen mineralization after clear-cutting. The nitrogen then leached into the surface water and groundwater. (Adapted from Likens and Borman 1995.)
As with agricult... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "The Extraction of Resources from Forest Ecosystems Involves an Array of Management Practices",
"token_count": 2036,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
North of the temperate coniferous forest is the circumpolar taiga, or boreal forest, the largest biome on Earth. Characterized by a cold continental climate, the taiga consists of four major zones: the forest ecotone, open boreal woodland, main boreal forest, and boreal–mixed forest ecotone.
Permafrost, the mainten... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "The Extraction of Resources from Forest Ecosystems Involves an Array of Management Practices",
"token_count": 478,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
- **1.** How do trees, shrubs, and grasses differ in their patterns of carbon allocation?
- **2.** What are tree buttresses?
- **3.** How does the warm, wet environment of tropical rain forests influence rates of net primary productivity and decomposition?
- **4.** What types of trees characterize tropical rain forest ... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "S tudy Questions",
"token_count": 1247,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
- 24.1 Lakes Have Many Origins
- 24.2 Lakes Have Well-Defined Physical Characteristics
- 24.3 The Nature of Life Varies in the Different Zones
- 24.4 The Character of a Lake Reflects Its Surrounding Landscape
- 24.5 Flowing-Water Ecosystems Vary in Structure and Types of Habitats
- 24.6 Life Is Highly Adapted to Flowin... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "Chapter Guide",
"token_count": 696,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Lakes and ponds are inland depressions containing standing water (Figure 24.2). They vary in depth from 1 meter (m) to more than 2000 m and they range in size from small ponds of less than a hectare (ha) to large lakes covering thousands of square kilometers. Ponds are small bodies of water so shallow that rooted plant... | {
"Header 1": "Ecologic al Issues & Applications",
"Header 3": "**24.1** Lakes Have Many Origins",
"token_count": 415,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
All lentic ecosystems share certain characteristics. Life in still-water ecosystems depends on light. The amount of light penetrating the water is influenced by natural attenuation, by silt and other material carried into the lake, and by the growth of phytoplankton (see Chapter 4, Quantifying Ecology 4.1 and Figure 20... | {
"Header 1": "**24.2** Lakes Have Well-Defined Physical Characteristics",
"token_count": 717,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Aquatic life is richest and most abundant in the shallow water about the edges of lakes and ponds as well as in other places where sediments have accumulated on the bottom and decreased the water depth (Figure 24.4). Dominating these areas is emergent vegetation such as cattails (*Typha* spp.) and sedges (Cyperaceae), ... | {
"Header 1": "24.3 The Nature of Life Varies in the Different Zones",
"token_count": 1174,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Because of the close relationship between land and water ecosystems, lakes reflect the character of the landscape in which they occur. Water that falls on land flows over the surface or moves through the soil to enter springs, streams, and lakes. The water transports with it silt and nutrients in solution. Human activi... | {
"Header 1": "24.4 The Character of a Lake Reflects Its Surrounding Landscape",
"token_count": 762,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Even the largest rivers begin somewhere back in the hinterlands as springs or seepage areas that become headwater streams, or they arise as outlets of ponds or lakes. A few rivers emerge fully formed from glaciers. As a stream drains away from its source, it flows in a direction and manner dictated by the lay of the la... | {
"Header 1": "24.5 Flowing-Water Ecosystems Vary in Structure and Types of Habitats",
"token_count": 1054,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Living in moving water, inhabitants of streams and rivers face the challenge of remaining in place without being swept downstream. Unique adaptations have evolved among these organisms
#### QUANTIFYING ECOLOGY 24.1 Streamflow
he ecology of a stream ecosystem is determined largely by its streamflow, which is the wat... | {
"Header 1": "24.6 Life Is Highly Adapted to Flowing Water",
"token_count": 1994,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Fast stream: (1) black-fly larva (Simuliidae); (2) net-spinning caddisfly (*Hydropsyche* spp.); (3) stone case of caddisfly; (4) water moss (*Fontinalis*); (5) algae (*Ulothrix*); (6) mayfly nymph (*Isonychia*); (7) stonefly nymph (*Perla* spp.); (8) water penny (*Psephenus*); (9) hellgrammite (dobsonfly larva, *Coryda... | {
"Header 1": "24.6 Life Is Highly Adapted to Flowing Water",
"token_count": 561,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
From its headwaters to its mouth, the flowing-water ecosystem is a continuum of changing environmental conditions (Figure 24.13). Headwater streams (orders first to third) are usually swift, cold, and in shaded forested regions. Primary productivity in these streams is typically low, and they depend heavily on the inpu... | {
"Header 1": "24.7 The Flowing-Water Ecosystem Is a Continuum of Changing Environments",
"token_count": 602,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
Waters of most streams and rivers eventually drain into the sea. The place where freshwater joins saltwater is called an *estuary*. Estuaries are semi-enclosed parts of the coastal ocean where seawater is diluted and partially mixed with freshwater coming from the land (Figure 24.14). Here, the one-way flow of freshwat... | {
"Header 1": "24.8 Rivers Flow into the Sea, Forming Estuaries",
"token_count": 1230,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The marine environment is marked by several differences compared to the freshwater world. It is large, occupying 70 percent of Earth's surface, and it is deep, in places more than 10 km. The surface area lit by the sun is small compared to the total volume of water. This small volume of sunlit water and the dilute solu... | {
"Header 1": "24.9 Oceans Exhibit Zonation and Stratification",
"token_count": 444,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
When viewed from the deck of a ship or from an airplane, the open sea appears to be monotonously the same. Nowhere can you detect as strong a pattern of life or well-defined communities, as you can over land. The reason is that pelagic ecosystems lack the supporting structures and framework provided by large, dominant ... | {
"Header 1": "24.10 Pelagic Communities Vary among the Vertical Zones",
"token_count": 1667,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
The term benthic refers to the floor of the sea, and benthos refers to plants and animals that live there. In a world of darkness, no photosynthesis takes place, so the bottom community is strictly heterotrophic (except in vent areas), depending entirely on the rain of organic matter drifting to the bottom. Patches of ... | {
"Header 1": "24.11 Benthos Is a World of Its Own",
"token_count": 895,
"source_pdf": "datasets/websources/biochem/Smith_Smith_2015.pdf"
} |
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