Chap 21 Landscape Ecology

鄭先祐 (Ayo)

靜宜大學 生態學系 教授

Ayo 台南站： http://mail.nutn.edu.tw/~hycheng/

Email add: Japalura@hotmail.com

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Fig. 21.1 The view from hills and mountains, such as this one, were used traditionally in ancient Japan to survey the surrounding lands.

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Introduction

13 世紀，日本帝王 Jomei 習慣每年的春季登上 Mount Kagu(Nara prefecture) 觀看週遭的地景。

更早的習俗，日本的農村於每年春季登上附近的山上，觀看其田野。 (kunimi)

觀看地景的習俗，包含 religious( 宗教的 ), esthetic( 美學的 ), economic( 經濟的 ), and political( 政治的 ) reasons.

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Landscape ecology

Is young as a scientific discipline. The emergence of landscape ecology

coincides with the widespread availability of aerial photos (Fig. 21.2) and satellite images (Fig. 21.3).

Landscape ecologists study landscape structure, processes, and change.

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Concepts

1. Landscape structure includes the size( 大小 ), shape( 形狀 ), composition( 組成 ), number( 數量 ), and position( 位置 ) of different ecosystems within a landscape ( 地景 ).

2. Landscape structure influences processes such as the flow of energy, materials, and species between the ecosystems within a landscape.

3. Landscapes are structured and change in response to geological process, climate, activities of organisms, and fire.

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Concept discussion 1

Landscape structure includes the size( 大小 ), shape( 形狀 ), composition( 組成 ), number( 數量 ), and position( 位置 ) of different ecosystems within a landscape ( 地景 ).

The structure of six landscapes in Ohio The fractal geometry( 不規則幾何圖形 ) of la

ndscapes

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The structure of six landscapes in Ohio

In 1981, Bowen and Burgess published a quantitative analysis of several Ohio landscapes. (Fig. 21.4)

Quantified patch shape by ratio of patch perimeter to perimeter of a circle with an area equal to that of the patch.

S = P÷(2√A) S = Patch shape( 形狀 )

Increasing value indicates less circular shape P = Patch perimeter ( 周長 ) A = Patch area ( 面積 ) Fig. 21.5(p.514) 和 Fig. 21.6(p.515)

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Landscape Structure

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The Fractal Geometry of Landscapes

Fractal geometry was developed by Benoit Mandelbrot (1982).

Bald eagles ( 禿鷹 ) vs. barnacles ( 藤壺 ) 巢間距 0.782KM vs. 個體間距 2cm(0.00002KM) The perimeter of the island is 760KM (eagles rule

r) The perimeter is 11,00KM (tiny ruler).

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Fractal Geometry of Landscapes

尺度

海岸線的長度

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Concept Discussion 2Landscape processes

地景構造影響地景過程 ( 功能 ) ，諸如 the flow of energy, materials, and species between the eco

systems within a landscape. the dispersal of organisms, local population density, extincti

on of local populations, and the chemical composition of lakes.

The dispersal of small mammals (p.517) The density of butterfly population (p.518) Habitat corridors ( 廊道 ) (p.519) Lake chemistry ( 湖泊化學 ) (p.520)

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Landscape Structure and Dispersal of Small Mammals

Ecologists have proposed landscape structure can influence movement of organisms between potentially suitable habitats. Metapopulations: Populations of many species

occur in spatially isolated patches, with significant exchange of individuals.

Rate of movement of individuals between subpopulations can affect species persistence in a landscape.

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Landscape Structure and Dispersal of Small Mammals

Fig. 21.11 Influence of patch size on small mammal movements

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Landscape Structure and Dispersal of Small Mammals

Diffendorfer et. al. studied how patch size affects movement of three small mammal species. Predicted animals would move farther in more

fragmented landscapes.Must move farther to obtain resources.

Predicted animals would stay longer in more isolated patches.

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Density of Butterfly Populations

Hanski et. al. (1994) found butterfly density significantly affected by size and isolation of habitat patches. Population size within patch increased with patch

area. Population density decreased as patch area

increased. Isolated patches had lower butterfly densities.

Population partially maintained by immigration.

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Habitat Patch Size and Isolation and Density of Butterfly Populations

Fig. 21.13 Relationship between habitat patch area and population size and density of the butterfly in a landscape.

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Habitat Corridors (棲地廊道 )

Connecting habitat fragments with corridors of a similar habitat has long been an approach to mitigating the effects of habitat fragmentation.( 減輕棲地的破碎化 ) Haddad and Baum (1999) found corridors influen

ced the movement of butterflies associated with early successional habitats.

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Landscape Position and Lake Chemistry

Webster (1996) explored how lake position in a landscape affected chemical responses to drought.

Lake position in landscape determined portion of water received as groundwater.

Fig. 21.15 Lake position in the landscape and proportion of water received as groundwater. (p.522)

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Landscape Position and Lake Chemistry

Fig. 21.15 Lake position in the landscape and proportion of water received as groundwater. (p.522)

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Concept discussion 3

Landscapes are structured and change in response to geological process, climate, activities of organisms, and fire.

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Soil and Vegetation Mosaics In Sonoran Desert

McAuliffe (1994) showed bajadas in Sonoran Desert are complex mosaic of distinctive landforms. Found wide range of soil types and plant

distributions that correspond closely to soil age and structure.

Soil structure influences perennial plant distributions.

Plant distributions map clearly onto soils of different ages.

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Soil and Vegetation Mosaics In Sonoran Desert Fig. 21.19

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Climate and Landscape Structure McAuliffe (1994): Soil mosaics consisted of pa

tches of material deposited during floods originating in nearby mountains. Materials eroded from mountain slopes and depos

ited as alluvium ( 沖積土 ) on surrounding bajadas. Alluvial deposits gradually changed; dependent up

on climate. Different soils and plant types. Fig. 21.20 Association between vegetation and soi

ls of different ages and structure on the Tucson Mountains bajada.

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Organisms and Landscape Structure

Many studies have focused on conversion of forest to agricultural landscapes. Eastern NA, many abandoned farms have

reverted to forest, thus forest cover has increased.

Similar patterns in parts of Europe.

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Organisms and Landscape Structure

Hulshoff (1995) found forest and heathland ( 石楠地 ) coverage changed over time as well as number and average area of patches. Cadiz Township - agricultural economy converted

area from forest to farmland. Economy collapsed in response to introduction of

synthetic fertilizers and inexpensive imported wool.

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Organisms and Landscape Structure

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Organisms and Landscape Structure African elephants knock down tress.

Change woodland to grassland. Kangaroo Rats dig burrow systems that

modify soil structure and plant distributions. Beavers cut trees, build dams and flood

surrounding landscape. At one time, beavers modified nearly all

temperate stream valleys in Northern Hemisphere.

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Organisms and Landscape Structure

Johnston and Naiman documented substantial effects of beavers on landscape structure. Over 63 yrs, area created by beavers increased

from 200 ha to 2,661 ha. Changed boreal forest landscape to complex

mosaic.

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Organisms and Landscape Structure

Beaver activity between 1927-1988 increased quantity of most major ions and nutrients in impounded areas. Three possible explanations: Impounded areas may trap materials. Rising waters captured nutrients formally held in

vegetation. Habitats created by beavers may promote

nutrient retention by altering biogeochemical processes.

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Fire and Structure of a Mediterranean Landscape

Minnich used satellite photos to reconstruct fire history of S. CA and N. Baja (1971-80). Landscape consisted of patchwork of old and

new burns. Similar climates with deviated fire histories: Fire suppression in S. CA allowed more biomass

accumulation and resultant large fires.Small burns more frequent in N. Baja.Other factors

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Applications & Tools

Riverine Restoration: The Kissimmee River The restoration project will take about 15 year

s and restore about 70km of river channels to a more natural condition and about 11,000 ha of wetlands.

The projected costs of repairing the damage to the Kissimmee landscape is $500 million.

The first phase of the restoration was completed in 2001.

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