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34928 results in Ecology and conservation

Page 1645 of 1747

  • 12 - Land transformation and fragmentation

  • from Part V - Changing Mosaics
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 405-434

  • Summary

    But when I consider that the nobler animals have been exterminated here - the cougar, panther, lynx, wolverine, wolf, bear, moose, deer, the beaver, the turkey, etc., etc. - I cannot but feel as if I lived in a tamed, and as it were, emasculated country … I listen to a concert in which so many parts are wanting … for instance, thinking that I have here the entire poem, and then, to my chagrin, I hear that it is but an imperfect copy that I possess and have read, that my ancestors have torn out many of the first leaves and grandest passages …

    Henry David Thoreau, Journal, 1856

    Robert Burns’ classic description of change as ‘Nature's mighty law; reminds us that whatever humans do, it is set within a changing land driven by natural processes. Furthermore, change, whether natural or human induced, is the norm. Short static or equilibrium phases are common within the broad dynamics. But persistent static phases are the exception, and they never persist indefinitely.

    The preceding chapters have explored the structural patterns and functional flows of mosaics during a static phase. This was useful for explanation, but in this and the following chapters we focus explicitly on the changing landscape or region. This chapter examines change driven by natural processes or by mainly unplanned human activities. The subsequent two chapters focus on change where human planning is also important.

    The subject of land transformation and fragmentation is significant to all human issues that involve land. Wise forestry, economics, biodiversity conservation, agriculture, landscape architecture, sociology, wildlife biology, soil science, and so forth explicitly recognize and deal with a dynamic land. These dynamics also characterize finer and broader scales, albeit at different rates, including succession within a patch1233,1029 and global climate change.1413,1158

    Many of the ideas and syntheses in this chapter were developed jointly with George F. Peterken; indeed, he is almost a coauthor of chapter 12. No overall review of the subject of this chapter exists. However, individual topics are reviewed as follows: fragmentation225,683,1793,1536,39; spatial processes683,501,1742,661; and geometric modeling of mosaic sequences.518

    Chapter 1 introduced the concepts of patch mosaic dynamics and landscape change.

  • 11 - Species movement in mosaics

  • from Part IV - Mosaics and Flows
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 364-402

  • Summary

    In our most trivial walks, we are constantly, though unconsciously, steering like pilots by certain well-known beacons and headlands, and if we go beyond our usual course we still carry in our minds the bearing of some neighboring cape; and not till we are completely lost … do we begin to find ourselves, and realize where we are and the infinite extent of our relations.

    Henry David Thoreau, Walden, 1854

    Dragons have played a key role in history and now are nearly extinct. This keystone species (or guild of species) apparently had population centers at least in Ethiopia, northern Europe, and China.738 The large ugly scaly reptile-relatives generally lived in deep caves, lakes, or rivers, and foraged singly across landscapes, both on the ground and in the air. They were attracted to virgins in distress, and repelled by heroes with swords. Chinese dragons were frightened by iron, centipedes, wax, leaves of the lien tree (Melia), and other objects. Populations fluctuated, with sighting records in Europe higher during the Middle Ages, in the seventeenth century when classification treatises were published, and in the nineteenth century when Darwin's evolutionary theory suggested relationships with known dinosaurs, such as pterodactyls. With increased human population and technologies including satellite images, remote habitats have decreased and dragon populations crashed. Most recent sighting reports have been of Chinese dragons, in areas where the species has traditionally received generosity and respect. But alas, too little information is available on how dinosaurs and these mythological dragons used pattern in moving across a landscape or region, the subject of this chapter. Therefore we must learn from movements of today's less fearsome animals and plants.

    The subject of species movement at this scale is critical in many arenas. Conserving biodiversity depends primarily on landscape and regional pattern. Forest regeneration in most regions depends on seed dispersal. Invasions of exotic species are inhibited or enhanced by landscape pattern. Plagues of insects or herds of herbivores attack crop fields one after another. And migratory fish move long distances through heterogeneous river systems.

    This chapter, along with the preceding one, is about movement across mosaics. It assumes familiarity with concepts in chapters 2, 3, 5, 8 and 9. Indeed, chapter 8 considers the resistance to species movement by a landscape, and chapter 9 examines species movement in mountains.

  • 10 - Wind and Water Flows in Mosaics

  • from Part IV - Mosaics and Flows
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 322-363

  • Summary

    Thus from generation to generation it goes bounding over lakes and woods and mountains … sailing … on various tacks until the wind lulls, to plant their race in new localities - who can tell how many miles away? … And for this end these silken streamers have been perfecting themselves all summer, snugly packed in this light chest, a perfect adaptation to this end - a prophecy not only of the fall, but of future springs.

    Henry David Thoreau, The Dispersion of Seeds, 1862

    Weather always seems to come from somewhere else. Storms, cold fronts, and dry air, produced by energy and water flows in adjacent or distant regions, keep rolling in. We, along with vegetation and animals, get frozen, broiled, desiccated and drenched. But the circulating air brings more than heat and water. Air-borne particles increase rain just downwind of most cities. Sulfur oxides and heavy metals from factories damage vegetation in a downwind plume. Dust from cultivated fields filters through the cracks of far-off houses.

    Weather and climate also depend on the internal characteristics of a landscape. The arrangement of land uses and the contrasts between adjacent ecosystems in the landscape help create or sustain flows of energy, water, and air. In short, both flows from outside and pattern within determine the wind and water flows in mosaics.

    The objective of this chapter is not to learn meteorology or global cycles, though bits of them are introduced. Rather, after eight chapters primarily exploring spatial pattern and its ecological significance, this is the leadoff chapter with principles focusing on flows, movements, and changes in the land mosaic.

    The principles in this chapter are a key to spatial planning, management, and conservation, because of the extensive flows among local ecosystems in a land mosaic. Plans and management schemes must highlight not only adjacencies (chapter 9), but sources and sinks at varying distances. Upwind and upslope sources of heat, water, and pollutants are highly significant in, for example, suburban development, nature reserve protection, crop growth, and forest production. Downwind and downslope sinks at various distances also affect the ecological characteristics of an ecosystem or land use.

Land Mosaics
  • The Ecology of Landscapes and Regions
  • Richard T. T. Forman
  • Foreword by Edward O. Wilson
  • Published online:
    12 October 2018
    Print publication:
    09 November 1995
  • Animals, plants, water, wind, materials and people flow at different rates, according to spatial patterns common to almost all landscapes and regions. This up-to-date synthesis explores the ecology of heterogeneous land areas, where natural processes and human activities spatially interact, to produce an ever changing mosaic. The subject has great relevance to today's society, and this book reflects the breadth of its importance; there are many ideas and applications for planning, conservation, design, management, sustainability and policy. Spatial solutions are provided for society's land-use objectives. An appealing book, with a highly-readable text on this major emerging field. Students and professionals alike will be drawn by the attractive and informative illustrations, the conceptual synthesis, the wide international perspective and the range of topics and research covered.

  • Preface

  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp xv-xix

  • Summary

    Virtually all the great questions of our time involve land. I rank the following near the top. Can we reduce the number of mushrooming megacities, environmental refugees, and regional wars? As human linkages to the land are severed, can we discover a way to rewrap humans and nature? Can biodiversity be protected? What is lost when civilization converts the soft curves of nature to the hard lines of geometry? Can we shift our attention from the local site or ecosystem to the whole landscape or region soon enough to reverse cascading degradation? Since space on the planet is finite and few will be global managers, is regional decision-making the key to global protection? Is there a way to accelerate sustainable thinking at the time scale of human generations. All wise answers have roots in landscape and regional ecology.

    The perspective in this book is captured by adding the following two middle lines to words in a classical Chinese verse (At Heron Lodge, by Wang Chih-huan, Tang Dynasty, 618-906; Bynner & Kiang 1929).

  • But you widen your view three hundred miles,

  • Then discover a mosaic,

  • And see it change,

  • By going up one flight of stairs.

    • The land as seen from an airplane window or on an aerial photograph is the subject of this volume. It is a specific object, with attributes amenable to analysis, modeling, and manipulation. Its ecology is the interaction between organisms and the environment. Productivity, biodiversity, soil, and water are central. Landscapes, from forested to dry and from suburban to cultivated, are explored, and regions composed of many landscapes are introduced.

    The ecology of spatial configuration at the human scale burst upon the scene barely a decade ago. Both theory and evidence were thin. But the potential of the conceptual framework and its application was obvious and far reaching. Theories, observations, models, and experiments crowd onto the pages of this book. The rapid transformation in thinking and the weight of accumulated knowledge are amazing. Applications are evident in all land-use areas. Yet the field is young, the uncertainties daunting, and the challenges exciting. Society urgently awaits the waiting discoveries.

    Landscape and regional ecology has its feet firmly in science. But science is but a slice of human understanding. Wisdom requires other slices. Much of the core of this subject has come from specialists in ecology and several related disciplines who call themselves landscape ecologists.

  • Foreword page

  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp xiii-xiv

  • Summary

    In the cloistered tradition of scientific specialization, most ecologists think of the world narrowly, as a system of natural environments beleaguered by human activity. They live, as Aldo Leopold put it, in a world of wounds. They have reason to think this way. Today, less than 10% of the land surface remains in a mostly unchanged state, and only 4% has been set aside in natural reserves. In their own specialty, planners and landscape designers tend to stay in their larger and wholly different world. For them, the bulk of the land has been given over to humanity; and now, they say, people must redesign it to their liking.

    Neither view, taken to exclusion of the other, is viable any longer. Ecologists increasingly recognize that they must extend their science to embrace artifactual environments. More reflective planners and landscape designers understand that they cannot afford to ignore organisms - the right organisms - needed to sustain a healthy, pleasing environment. A few scholars, of which Richard Forman is a notable example, have come to focus on the intellectually rich domain of overlap between the two fields. The result of their deliberate intermediacy is the new discipline of landscape ecology.

    In Land Mosaics, Forman joyously embraces the human-altered environment and proposes that its living part can be improved by use of the best principles of environmental biology. He recognizes, as the book's title implies, that the real world consists of finely fragmented habitats. The pieces range from radically altered urban parks and gardens to remnant pockets of the original environment. Across periods as short as a few years, living species arrive, impinge, dominate, yield, and disappear in this kaleidoscope. The vast majority of the inhabitants we never see, because they are too small and obscure: creepy-crawlies, immense in diversity, from insects to fungi and bacteria. All together, they are as important as the towering trees and the birds on which our attention is ordinarily focused. The species that can survive in the habitat fragments come together to determine the health and beauty of the places in which we live.

    Forman and other scientifically educated landscape ecologists address the question: ‘Given that humanity is now in charge of most of the land surface, and responsible for it, what designs of the terrestrial landscape are best for the rest of life, and therefore for us?'

  • 3 - Boundaries and Edges

  • from Part II - Patches
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 81-112

  • Summary

    There is something indescribably inspiriting and beautiful in the aspect of the forest skirting and occasionally jutting into the midst of new towns … Our lives need the relief of such a background, where the pine flourishes and the jay still screams.

    Henry David Thoreau, A Week on the Concord and Merrimack Rivers, 1849

    Artists and photographers use contrast to create stunning images. High contrast is attained by accentuating the difference between adjacent areas, and by sharpening the boundary. This chapter focuses on the myriad types of boundaries that separate ecosystems or land uses in a landscape (Fig. 3.1).

    Of what use are these boundaries within a landscape? In wildlife management edges typically have an abundance of game and other animals that move along or across boundaries. In questions of biodiversity and land fragmentation, the ratio of edge to interior habitat is critical. In aesthetics, views are often dominated by edges. In forestry, edges are commonly characterized by crooked trunks and blowdowns. In agriculture, edges are often the source of pests, as well as predators controlling pests. In soil erosion control, boundaries cause wind speed changes and turbulence. In park and nature reserve management, boundaries may be barriers to human overuse. In detecting global climatic change, boundaries are often proposed as a sensitive indicator, the ‘canary in the mine'. And in sustainability issues, humans are edge species, but by carving up the land and increasing edges enormously, we eliminate the key values of large patches, thus degrading our landscapes.

    Useful literature reviews are available for boundary ecology as a whole (Holland et al. 1991, Hansen & di Castri 1992), as well as for ecotones360,1769,403 and the edge effect as related to biodiversity and wildlife.1700,684,1941 Boundaries between land and water are analyzed in chapter 7.

    The present chapter begins with the structure of boundaries, and the developmental mechanisms controlling them. Next, functions are presented, including the edge effect and movements and flows across boundaries. Width and curvilinearity are examined as major variables affecting both anatomy and flows. Finally we explore boundaries moving on the land.

    TYPES AND ABRUPTNESS

    Boundary types and theory

    In chapter 1 we noted that introducing energy causes a system, such as a landscape, to become spatially heterogeneous in one of two ways.503

  • 5 - Corridor Attributes, Roads, and Powerlines

  • from Part III - Corridors
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 145-176

  • Summary

    We have an account in the newspapers of every cow and calf that is run over, but not of the various wild creatures … It may be many generations before the partridges learn to give the cars a sufficiently wide berth.

    Henry David Thoreau, Journal, 1858

    Nature creates corridors in the form of streams, ridges, and animal trails. Humans create roads, powerlines, ditches, and walking trails. How do the two types differ? Nature's are curvy, until humans straighten them. Nature's are continuous until humans superimpose grids on them, and create gaps. Human corridors are generally narrow and costly to maintain.

    Corridors, as strips that differ from their surroundings, permeate the land. Vegetation corridors contribute significantly to many goals of society, here lumped into six categories.491 First, corridors provide biodiversity protection, including key riparian habitats, rare and endangered species, wide-ranging species, and dispersal routes for recolonization following local extinction. Second, corridors enhance water resource management, such as flood control, control of sedimentation, reservoir capacity, clean water, sustainable fish populations, and fishing. Third, linear strips may enhance agroforestry production by acting as windbreaks for crops and livestock, controlling soil erosion, providing wood products, and preventing desertification. Fourth, recreation in corridors includes game management, wildlife conservation for nature enjoyment, and hiking, bicycling, boating, and skiing in suburban greenbelts. Fifth, community and cultural cohesion may be enhanced with greenbelts, which create neighborhood identity, provide wildlife corridors crossing roads that concurrently inhibit strip (ribbon) development along a road, and function as regional topographic barriers that enhance cultural diversity. Sixth, corridors provide dispersal routes for species

    isolated in nature reserves, and coastal strips threatened by rising sea level in the event of climatic change.

    Useful reviews of corridor attributes are given by Forman & Godron

    (1986), Schreiber (1988), Brandie et al (1988), Bennett (1990a, 1991),

    Saunders & Hobbs (1991), Forman (1991), Malanson (1993), and

    Smith & Hellmund (1993). Reviews of specific topics include the corridor

    as a conduit685,688,1228, the corridor as a filter174,1038,130, road and roadside

    vegetation109,111,1492, and trails.968,1842

    Windbreaks, hedgerows, and wooded strips are presented in chapter 6, and stream and river corridors in chapter 7. Corridors are also commonly interconnected to form networks, as explored in chapter 8.

    This chapter begins with general patterns and principles that apply to virtually all corridors.

  • 14 - Creating sustainable environments

  • from Part V - Changing Mosaics
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 480-524

  • Summary

    Only when the city, the hamlet, or the cottage is viewed from a distance does man's life seem in harmony with the universe … The sunlight on cities at a distance is a deceptive beauty, but foretells the final harmony of man with Nature.

    Henry David Thoreau, Journal, 1841

    Dreams of Utopia have sparked the establishment of communities in every century. Social, political, or religious fervor and commitment have created such communities, especially in rural landscapes. Yet rather few of these experiments have lasted a century. At the other extreme are civilizations and societies that have continued for centuries and even millennia (Fig. 14.1). In all cases success or failure depends both on human dimensions and the land.

    Two central components of sustainability are thus introduced. The time frame is over human generations, and the key characteristic is a dynamic with equal emphasis on human and environmental dimensions. The preceding chapter on land planning and management elucidated principles based on this combination of land processes and human resource use. But the time scale was years (or up to a few decades), the normal framework for planning, design, conservation, management, and policy. The difference in time scale is the primary characteristic separating sustainability from normal year-to-year planning. For planning over human generations, if we are to learn from history, the most instructive history is of human-land interactions over two or more centuries.286

    Most sustainability literature focuses on the globe.1414,286,1929,768 Only a few countries have begun seriously addressing the implications of sustainability.434,1002,1431,476,778 Although this chapter touches on the built environment, the idea of sustainable urban development is not directly addressed. However, agriculture, economics, forestry, fisheries, sociology, and more recently ecology have taken a particular interest in sustainability, often considering it within their own disciplines. Surprisingly, the role of spatial arrangement of land is commonly overlooked.. Little literature on sustainability exists at the landscape and regional scales.492 Yet these scales may be the most important for attaining sustainability.

    This chapter assumes general familiarity with principles in most preceding

    chapters; indeed many points will otherwise be unclear or counterintuitive.

    The chapter begins with the basic concepts of sustainability.

    It then focuses in detail on key sustainability attributes, organized by

    time, space, humans, assays, and adaptability. Next, we learn from

    human histories, and briefly revisit regional ecology.

  • 1 - Foundations

  • from Part I - Landscapes and Regions
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 3-40

  • Summary

    Nature, the earth herself, is the only panacea.

    Henry David Thoreau, Journal, 1859

    Five minutes after leaving a tropical city one of the plane's two engines dies. The plane begins dropping. Rich primeval rainforest awaits on one side, and town-dotted farmland on the other. Someone snaps an instant photograph, carries it to the open cockpit, and the pilot explodes in laughter. The passengers remain petrified until we slip over a ridge and bounce onto an unlighted runway.

    The object spread out beneath an airplane window, or on an aerial photograph, is the subject of this book. Indeed, an aerial vantage provides a goldmine of information on the ecology of large land areas, such as landscapes and regions. For example in Fig. 1.1, one can predict with some confidence that the forest has many more interior species than the wooded patches on the right. Animal movement funnels through the lobes or peninsulas of the forest. Wind erosion is high in the corridor gaps on the left. Cool-water fish are probably missing from the stream in the far right. The clearing at the top has been expanding, while the clearing below it is contracting. The ecologically optimum location for a cluster of houses is by the field-forest edge in the upper right. The evidence for interpretations such as these and many more is presented in this book. Of course, dropping from the sky to examine the land closely is also essential.

    MOSAICS AND THE PATCH-CORRIDOR-MATRIXMODEL

    From an airplane, land almost always appears as a mosaic. The glorious mosaics of St. Mark's in Venice or the University of Mexico appear as a pattern of colored patches and strips, usually with a background matrix. Tiny stones of different colors are aggregated to create the patches, strips, and matrix. The land appears much the same. Individual trees, rocks, houses, and so forth are the tiny stones. Woods, fields, and housing tracts are conspicuous patches. Roads, hedgerows, rivers, and powerlines are equally striking corridors. Grassland, forest, rice culture, or another land use often forms a background matrix. In short, the individual trees, shrubs, rice plants, and small buildings, analogous to the tiny stones in the artist's mosaic, are aggregated to form the pattern of patches, corridors, and matrix on land.

  • 13 - Land planning and management

  • from Part V - Changing Mosaics
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 435-479

  • Summary

    A river, with its waterfalls and meadows, a lake, a hill, a cliff or individual rocks, a forest, and ancient trees standing singly … If the inhabitants of a town were wise, they would seek to preserve these things, though at a considerable expense; for such things educate far more than any hired teachers or preachers, or any present recognized system of school education. I do not think him fit to be the founder of a state or even of a town who does not foresee the use of these things …

    Henry David Thoreau, Journal, 1861

    'Think globally, act locally’ is a phrase much in vogue. Yet it has two problems. First, few people will ever give primacy to the globe in decision-making. Second, local considerations overwhelmingly determine actions. Indeed, these are two roots of environmental and societal problems etched widely in the land. Typically, our best soils are thinned by erosion or covered by suburbs; biodiversity and wildlife in large wooded areas are impoverished by dispersed logging; critical riparian and hedgerow corridors are cut or razed by macroagriculture; productive land is desertified by irrigation and overuse; and parks are surrounded by the tightening noose of development.

    Can this unraveling of the land, as the primary capital of a nation, be reversed? Land patterns seem logical and ecological in exceptional places within, for example, Britain, Romania, Costa Rica, Australia, and the USA, as well as in certain spatial models. In these cases efforts in design, planning, conservation, and decision-making seem both visionary and practical. They are directed at agricultural landscapes, suburban landscapes, forested landscapes, or regions. At these scales the environment, economics, and society coalesce. The landscape and region are the central linkage between global and local.

    The philosophic framework for this chapter therefore might be that we better ‘Think globally, plan regionally, and then act locally .

    The perennial challenges in planning, design, and management of an area are not only to take a broad spatial view and a long temporal view, but also to address all major environmental and human issues present. Water, transportation, biodiversity, aesthetics, sense of community, food production, and much more are the essential factors.

  • 2 - Patch Size and Number

  • from Part II - Patches
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 43-80

  • Summary

    … nature thus keeps a supply of these plants in her nursery (i.e., under the larger wood), always ready for casualties, as fires, windfall, and clearings by man.

    Henry David Thoreau, Journal, 1860

    The landscape mosaic was presented as a whole in chapter 1. Now we begin dissecting it into its building blocks, beginning with patches. A patch is a wide relatively homogeneous area that differs from its surroundings (see glossary in chapter 1 appendix). Patches have familiar attributes, such as large or small, rounded or elongated, and straight or convoluted boundaries. These attributes in turn have widespread ecological implications for productivity, biodiversity, soil, and water.

    Why are these patch characteristics so important? In forestry the size of woods affects road construction and erosion, how many trees are wasted in edge effects, and the success of tree reproduction. In suburbanization planning the size of housing developments and nature reserves are common controversial issues. In aquifer and lake protection water quality depends on a large patch of natural vegetation. In managing stream systems for fish and fishermen, the size and number of natural patches is critical. In nature reserve design, is it better to have one large patch or several small patches? How many large patches are required to maintain the biodiversity of a landscape? In managing game, small patches are frequently created. And in agriculture an optimum field size has both ecologie and economic implications.

    Several of the topics included are reviewed by Forman & Godron (1986). Other useful reviews include: patch dynamics1320; the traditional species-area concept; island biogeographic theory1023,1323,302,564,1901,198,1763,1536; remnant patches in landscapes683,1490,1536; and genetics in patches1595.

    This chapter begins with the origins and half-life of dynamic patches. Patch size effects are examined for ecosystem processes. Species-area curves and island biogeographic theory lead to evaluating species numbers in remnant and disturbance patches in a terrestrial mosaic. The roles of genetics and minimum viable populations are introduced. Finally we evaluate the importance of number of large patches present.

    PATCH DYNAMICS: ORIGIN AND PERSISTENCE

    The fortuneteller who predicts change is always right. We may dream of constancy or stability, but change, the universal law, is a key to understanding. Indeed, because change always extends over a limited area, it causes or affects a patch.

  • 8 - Networks and the Matrix

  • from Part III - Corridors
  • Richard T. T. Forman, Harvard University, Massachusetts
  • Foreword by Edward O. Wilson
  • Book:
    Land Mosaics
    Published online:
    12 October 2018
    Print publication:
    09 November 1995, pp 253-282

  • Summary

    Near the lake, which we were approaching with as much expectation as it had been a university, - for it is not often that the stream of our life opens into such expansions …

    Henry David Thoreau, The Maine Woods, 1848

    A sandbox is an ideal place. Children are protected from the outside, and become engrossed in creating their own micro-landscapes. They draw networks that crisscross and squiggle. They smooth the surface with their hands forming a surrounding matrix. And together they create a mosaic for the whole sandbox. The mosaic is continually changed and molded, and usually punctuated by big disturbances.

    Everyone should have a sandbox, even a tiny one for fingers. The soothing effect, the manifest creativity, and the modeling for landscape and regional ecology are rich benefits. Metaphorically we are the children and the world is our sandbox. To get along and still have a nice sandbox, we need to find land designs that make sustainable sense. Networks and the matrix, analogous to those molded by the children, are the subject at hand.

    This chapter moves to a new level. Preceding chapters have explored the attributes of patches and corridors, the building blocks of landscapes. Movements and flows to and from adjacent land have been included as patch-matrix or corridor-matrix interactions. Now we explore the matrix, and hook building blocks together to form mosaics. Patches, corridors, and matrix are combined in distinctive ways to create the finite number of common mosaics on land.

    The primary importance of this subject is planning. One may sculpt an individual patch or corridor to attain desired objectives. But sculpting a matrix or network of several spatial elements on a farm, park, forest, refuge, or town requires planning by the owner or manager. And creating a logical mosaic for a whole landscape or region requires regional and government planning.

    Perhaps the only overview of the subject is by Forman & Godron (1986). However, useful reviews of portions include: transportation networks1670,995,646,1518; hedgerow networks1337,948,1114,1116; windbreaks174; and the matrix.501

    The chapter begins with the development of networks, and how to measure them. Dendritic and rectilinear networks are contrasted, and the functioning of networks is explored. Next the structure of a matrix is presented. And we conclude with matrix dynamics.

Page 1645 of 1747