Physical environment Smith and Smith, 2006 Biogeography Prof. J. Hicke 1

Transcription

1 Smith and Smith,

2 Soil moisture controls on woody plants in desert Southwest Lomolino et al

3 Moisture stress on plants: mortality Croplands Pinyon pine in SW Photo by Craig Allen - USGS 3

4 Soil moisture controls on tree species distribution in PNW Barnes et al.,

5 Rooting depth in arid landscape controls species distribution Elmore et al.,

6 Controls of soil moisture at larger scale Precip Biomass Veg type dry wet none high none shrublands savannas dense forest dry none 6 Friedl et al.

7 Plant strategies to deal with drought: 1. Escapees Perennials (dormancy) Annuals ( emphemerals ) 7

8 Plant strategies to deal with drought: 2. Avoiders Slide courtesy C. Still 8 DeFries et al., 2000

9 Plant strategies to deal with drought: 2. Avoiders Slide courtesy C. Still 9

10 Adaptation to low moisture conditions: Idaho forest Soil water redistribution-water flows uphill! slide courtesy of K. Kavanagh 10

11 Annual water balance Sierra Nevada, CA: Coniferous Eric, PA: Deciduous soil water recharge surplus deficit surplus Water supply PET AET Stephenson, 1998 Stephenson,

12 Three reasons conifers dominate over deciduous trees energy limited => low AET Water supply PET water limited => low AET AET asynchrony in energy, water supplies => low AET 12 Stephenson, 1990

13 Distribution of major N. America plant formations AET: separation of different forest types Deficit: separation of forest types from prairie 13 Stephenson, 1990

14 Rain isn t everything: N. California coastal forest fog is 22-46% of hydrologic inputs; timing is everything! Dawson

15 Extremely wet soils Adaptations: adventitious roots longitudinal air spaces aerating roots Mangroves (Avicennia) en.wikipedia.org/wiki/root 15

16 Adaptations to low water availability kangaroo rat (Dipodomys spectabilis) can live entirely on dry food without ever drinking free water 100 g dried seed => 54 ml of water through oxidation only very small quantities of feces, urine do not sweat; little evaporation nocturnal behavior during milk production, females need to eat green and moist plants Vorhies, museum.utep.edu/chih/theland/animals/mammals/dipospect.gif

17 Adaptations to low water availability Namib Desert beetle (Onymacris unguicularis) morphology adaptations to capture fog: bumps on back channels to mouth head down behavior can capture 40% of body weight in one morning

18 Soil type controls on species distributions Example: Serpentine soils dry and nutrient poor toxic to most plants support grasses adapted to these conditions as a result, associated animals are also located in these areas Smith and Smith,

19 Soil fertility influences plant species distribution: Tolerance to calcium % of total basal area within stand Replaceable calcium 19 Waring and Major, 1964

20 Soil texture (moisture) effects on distributions greatest water availability: greater productivity, diversity rapid water infiltration: plants need to respond quickly poor water infiltration: sparse, shallow rooted shrubs 20

21 Soil texture influences on biogeography 21 Smith and Smith, 2006

22 Anoxic conditions Result from: lack of plants lack of mixing Excess fertilizer => phytoplankton blooms => zooplankton blooms => decomposer bloom => O 2 depletion 22 Ferber 2004

23 Acid rain Tolerance of acidification within lakes Little Echo Pond Acid_Rain_And_Forest_Mass_Another _Perspective.html Increasing acidification 23

24 What factors limit white spruce at its northern and southern extent? Summer temperatures Moisture stress (high summer temps, low precip) 24

25 Controls on Net Primary Production Nemani et al.,

26 Transect across Pacific Northwest transect 26

27 Transect across Pacific Northwest 27

28 Transect across Pacific Northwest forests shrublands /croplands forests grasslands /croplands 28

29 Transect across Pacific Northwest forests shrublands /croplands forests grasslands /croplands 29

30 Range and density 30

31 Population density follows physiological functioning (which is controlled by environment) Gradients in physiological functioning often follow Gaussian distribution Environmental gradient 31

32 Environmental gradients control niches Pinus ponderosa Pinus ponderosa Pseudotsuga menziesii Pseudotsuga menziesii McKenzie et al.,

33 Variability among species in tolerance to environmental conditions Redwood (Sequoia sempervirens): large range of ecological optimum Others: narrow range Which are generalists? Specialists? 33 Waring and Major, 1964