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This chapter provides a very brief history of plant ecology, and historical figures in the field, focusing on how previous ecologists have influenced the ways ecologists typically measure plant diversity today. It draws additional attention to the authors of two textbooks, Rexford Daubenmire, and Dieter Mueller-Dombois and Heinz Ellenberg, because they seem to reflect best the development of many current plant diversity field methods. Lastly, the chapter discusses the general direction provided by past plant ecologists, and the “baggage” of older ideas — how inertia developed and persists in modern plant ecology regarding measuring plant diversity.

A major aim in ecology is to understand the determinants of plant community structure. Here we focus on mutualisms and how these positive interactions between distinct species influence plant community structure and the organization of plant communities. Although mutualisms have been described as mathematically unstable, key evolutionary events such as the origin of the eukaryotic cell, invasion of land by plants and radiation of the angiosperms have been linked to mutualism. Mutualisms can enhance diversity and influence community organization via numerous routes, including habitat modifications, the acquisition of food sources, dispersal and protection. Disruptions of mutualistic interactions can cause declines in population sizes of organisms involved in such interactions and even lead to shifts in community composition. Mutualisms provide partner species with novel options for adjusting to stress and may play a critical role in regulating organization, structure and function of communities through activities that regulate the acquisition of resources and ameliorate stresses. Mutualisms may mediate the outcome of interspecific interactions such as competition and facilitate the coexistence of competing species. In this chapter we focus on the role that mutualisms play in plant community organization.

The strength of Lake Mills' plant-community identity, its historic vertical integration, and its domestic market orientation all combined to inhibit cooperation with other plants within APV to improve the effectiveness of the parent company as a multinational association. There was, in short, no American equivalent to the Danish Mafia, nor could such a network be easily imagined from the perspective of Lake Mills. Without the institutional resources and external allies to support a more expansive vision of the plant's future, local unionists and managers understandably fell back on a slew of defensive carrot-and-stick strategies for maintaining its position within APV. On the positive side, they sought to reinforce Lake Mills' indispensability to the multinational by providing a quick turnaround service to the company's large US customer base, and by developing new products tailored to US technical standards.

This chapter examines the various ways that plants and soil biota influence each other, and highlights some of the recent findings on the links that exist between plants and soil biological communities. First, it discusses some of the ways that plants, and changes in the diversity and composition of plant communities, can modify soil biological communities and their activities. Second, the issue of how soil biota can in turn influence plant growth and also act as agents of vegetation change, both in the short- and longer-term is considered. The ultimate goal of the chapter is to illustrate the nature and ecological significance of linkages between plant and soil communities at the community and ecosystem scale.

This chapter discusses the development of the livestock industry and grazing management and policy in the United States. It describes the climatic and vegetative conditions in the four major beef-producing regions in the United States: the Southeast, the Great Plains, the Intermountain West, and the California grasslands. It also discusses grazing ecology and grazing systems, addressing the effects on plant community structure (plant succession and the development of holistic management), the effects on plant community production, and the multiple life-form vegetation concept of the Intermountain West.

Plant communities in different types of wetlands vary greatly in species composition, species richness, and productivity. They are influenced to varying degrees by a long list of abiotic factors including hydrologic conditions, position on the landscape, substrate, fertility, climate, environmental stress, and disturbance, and also by a variety of biotic interactions including competition, facilitation, and herbivory. Plant communities range from highly productive herbaceous marshes dominated by a few robust perennial species to infertile but species-rich wet meadows. This chapter deals with wetland plant communities and the general principles that apply to different wetland types. It begins by presenting general concepts about how plant communities in wetlands are structured by abiotic and biotic factors. The chapter then considers the general factors that regulate plant growth and primary productivity in wetlands. It concludes by describing major wetland types.

The sagebrush steppe is generally comprised of treeless, shrub-dominated communities along the eastern and northeastern boundary of California. This chapter discusses the characteristics, climate, and topography of the sagebrush steppe, focusing on the potential plant communities that comprise the natural vegetation of the Artemisia steppe of California. These communities are identified by dominant shrub and herbaceous species. The chapter also provides examples of several plant communities that currently characterize much of the Artemisia steppe of California.

This chapter describes the tall volcanoes and extensive lava flows that characterize the Northeastern Plateaus bioregion. This region represents California’s portion of the Great Basin. There are four basic fire weather patterns that can significantly affect fire behavior and natural ignitions in northeastern California during the May-to-October fire season. These are: the pre-frontal winds, lightning with low precipitation, moist monsoon, and strong subsidence/low relative humidity patterns. Additionally, the fire responses of important species and fire regime-plant community interactions in the sagebrush steppe, the lower-montane zone, the mid-montane zone, the upper montane zone, the subalpine zone, and the non-zonal vegetation are outlined. Changes to fire regimes have caused changes in plant community composition and structure, and wildlife habitat in many plant communities. Fire continues to be an important ecological process throughout the Northeastern Plateaus bioregion but its role has greatly changed.

This chapter describes the Central Valley bioregion, showing that Sacramento and San Joaquin rivers flow through broad interior valleys with extensive, nearly flat alluvial floors. The Central Valley exhibits distinct and neatly arranged ecological zones. The fire ecology of important species and fire regime-plant community interactions in foothill woodland, valley grasslands, riparian forests and freshwater marsh are also reviewed. The Central Valley is arguably the most highly altered bioregion in California. Recent efforts have shown how commonly used management practices affect grassland composition and how various environmental factors interact with these practices. Throughout much of the twentieth century, agricultural burning was a common practice in the Central Valley.

This chapter uses serpentine plants to explore the trade-offs among rarity, representation, and connectivity in systematic land-based conservation. It analyzes a serpentine-rich landscape in the region of Napa County, California, from three perspectives: (1) the existing network of protected areas, relatively little of which is the product of biodiversity considerations; (2) the program Marxan, a widely used reserve design algorithm that identifies spatial solutions to user-determined objectives, one of which is typically the representation of all plant community types; and (3) least-cost corridor analysis, an algorithm that identifies large blocks of undisturbed habitat and the linkages between them which are most likely to provide connectivity for wildlife movement. By comparing how well the plant communities and known occurrences of rare plant species on serpentine and non-serpentine soils are protected under each of these approaches, the degree to which serpentine floras have unique conservation requirements can be assessed.

This chapter suggests that plant species and communities found on serpentine and other special soils share a number of ecological attributes which may cause them to respond differently to climate change than more typical species and communities in the same regions: (1) They are confined to relatively small and spatially isolated outcrops, where migrating to track the shifting climate will be exceptionally difficult; (2) They occur on infertile soils, where nutrients may be more limiting to plant growth than temperature or water, and where stress-resistant plant traits may confer resistance to climate change; (3) Their distribution and composition are the products of a competitive balance between soil “generalists” and soil “specialists” which are likely to be altered under a changing climate. After elaborating on each of these issues, preliminary evidence is considered from a suite of related studies that compare the responses of serpentine and nonserpentine plant communities to climate change.

This chapter describes the vast southeast corner of California that constitutes the Southeastern Deserts bioregion. It considers elevation to be the primary determinant of fire ecology zones in the desert bioregion. The primary factor controlling fire occurrence in the desert bioregion is the fuel condition, specifically fuel continuity and fuel type. The basic fire ecology of the predominant plant species in the low-elevation desert shrubland zone, the middle-elevation desert shrubland and the grassland zone, the high-elevation desert shrubland and the woodland zone, the desert montane woodland and the forest zone, and the desert riparian woodland and the oasis zone is reported. The chapter also explores the patterns of post-fire succession, and interactions among plant communities, fire behavior, and fire regimes. Fuel management can be a very important tool for fire managers in the California desert bioregion, even though the areas in which it is used may be a small percentage of the total region.

A clear understanding of how communities are assembled is essential to understand how ecosystems function, how global change impacts are altering ecosystems and the functions they perform, and how best to manage ecosystems for desirable outcomes. The composition and diversity of communities is determined by a range of community assembly processes and greatly influence the functions that these communities and ecosystems perform. Human activities alter many community assembly processes and are rapidly changing the composition, diversity, and function of communities. This chapter reviews and discusses what is known about (1) the assembly of plant communities in the Greater Cape Floristic Region, (2) the effects of composition and diversity on various ecosystem functions, (3) how human activities are negatively impacting on composition, diversity, and function, and (4) how community assembly processes can be and are being manipulated for positive outcomes.

Mangrove vegetation related to the modern tropical Asian palm, Nypa, was present along Africa's coasts at low latitudes in the Paleocene and Eocene, and pollen evidence of other palms is common. This chapter reviews and interprets the paleobotany and paleogeography of Africa during the Cenozoic. It presents a dynamic view of changes in plant communities and ecosystems through time, so that the evolutionary and biogeographic history of Cenozoic African mammals can be considered in the context of the communities to which they belonged. To facilitate this goal, the chapter explores environmental change in the context of major physiographic change such as graben formation associated with rifting in East Africa, and shows paleobotanical sites in their correct position on paleogeographic maps. A common challenge to providing a floral context for the mammalian fossil record stems from the fossilization process itself. The circumstances in which bones and plants become fossils are not often the same, and consequently they are rarely found together.

Humans have lived in or relied on wetlands for food and materials throughout history, and many former settlements in wetland-rich areas have grown into major cities. This urban development has resulted in direct losses of vast areas of wetlands due to drainage, filling, and excavation, as well as impacts to remaining wetlands associated with watershed alteration. Urban wetland plant communities are typically characterized by species adapted to physical disturbance, which often means those having weedy or invasive characteristics. Non-native invasive plants are often more abundant in urban wetlands than rural or remote wetlands, and although they can contribute significantly to the diversity of the community species richness may be locally reduced due to competitive exclusion. Nonetheless urban wetlands are often hotspots of biodiversity, and may support species that are rare, native, and common that are important for conservation efforts. Plant communities in urban wetlands differ from those of rural or remote regions because of the overriding influence of the urban environment on factors affecting plant growth and community development. For example, relative to wetlands in other land use types, urban wetlands often experience flashier hydrology, higher nutrient and sediment loads, higher temperatures, more physical disturbance, more invasive plant species and herbivorous animals, greater fragmentation, fewer forested buffers, and greater distances between wetlands. Despite their altered plant communities, the wetlands remaining in urban regions are particularly important given the ecosystem and socioeconomic services they provide, many of which derive directly from the plant communities they support.

Rush Ranch includes the largest remaining tidal marsh within Suisun Marsh of the San Francisco estuary. Estuarine geomorphic units frame its diverse wetland vegetation, influenced by estuarine position, land-use history, and the hydrogeomorphic structure of the site. The geomorphic-vegetation units (subtidal channel beds, fringing tidal marsh, tidal marsh plain, and tidal marsh-terrestrial ecotones) are distinguished by variations in hydrology, substrate, and elevation. We consider the vegetation with each landform as a function of past and modern physical processes and biological interactions. Historical land uses and exotic plant invasions have substantially altered Rush Ranch tidal-marsh vegetation and species diversity. Rush Ranch's landscape position provides important and increasingly rare terrestrial ecotones between the tidal marsh and lowland grasslands, providing potential for estuarine transgression with rising sea level.

The assembly rules which determine the composition of communities are based on the hypothesis of combined effects of different environmental filters on the regional pool of individuals: stochastic dispersal events determine which species are potentially available; local abiotic conditions select for species able to tolerate these conditions; and biotic effects determine the coexistence of interacting species. The functional structure of a community, i.e. the distribution of trait values, can be quantified by the community weighted mean of a trait and indices of functional divergence. It varies as a function of the relative importance of filters. When the abiotic filter selects individuals on the basis of their tolerance of resource availability, this leads to a restriction in the range of trait values relevant to resource use, and a convergent distribution with little dispersion around the mean. When this filter is linked to disturbance, it can lead to an over-dispersion or divergence of trait values, especially those linked to regeneration. The biotic filter can have contrasting effects on trait distributions, depending on the relative importance of the limiting functional similarity and competitive exclusion. The functional structure of a community depends on the intra- and interspecific variability of traits, whose relative importance varies with spatial scale. The structure of a community can also be described by assessing the phylogenetic diversity. Assuming that closely related species have more similar trait values than distantly related species, the chapter discusses whether the phylogenetic structure of a community can be used to infer its functional structure.

In antagonistic interactions, the fitness of individuals of one of the interacting species increases, while that of individuals of other interacting species decreases as a result of the interaction. Basically, antagonistic interactions occur between species because living organisms are concentrated packages of energy and nutrients (trophic interactions) and because resources are limited (competition). Antagonistic interactions can be divided into four basic types: parasitism, grazing, predation, and competition. Ants and plants are associated basically in two categories of antagonistic interaction: grazing (leaf-cutting ants) and predation (seed-harvesting ants). Due to the large numbers of seeds removed by ants and the often intense interspecific competition for seeds among ants, granivory and seed harvesting have been considered to be important interactions structuring plant communities. The relationship between antagonism (seed predation) and mutualism (seed dispersal) may be based on the availability of unspecialized seed-collecting ants that contribute to the prevalence of myrmecochory. This chapter reviews leaf-cutter and seed-harvesting ant systems, focusing on the interactions and their effects on the plant community.