Biomes Global Patterns of Life Glaciers shrinking in

Biomes: Global Patterns of Life Glaciers shrinking in a warming world – Chacaltaya Glacier, Bolivia 1

TERRESTRIAL BIOMES • Biomes - Areas sharing similar climate, topographic and soil conditions, and roughly comparable communities. v Temperature and precipitation are among the most important determinants in biome distribution. v Most terrestrial biomes are identified by the dominant plants of their communities. v Plants share adaptations, but are different species in different continents. s 2

Surface temperatures over time 3

Patterns of sea level, 1993 -2000 4

Dominant mixes of ecosystems show global patterns 5

Human Disturbance 6

For Discussion • With climate change, the distributions of many species are expected to change. What mechanisms might be examined to test this? v hint: how is this related to concepts of “niche”? v • With climate change, the distributions of biomes are expected to change. How is this different from question 1? v What mechanisms would lead to this? v 7

Questions • • • How does climate influence the form of dominant ecosystems? How can we agree on defining dominant ecosystems? How do humans directly influence biomes? v Can areas of biomes “collapse”? v “Collapse” = irreversible change to simpler state 8

Climate influences dominant growth forms of natural vegetation hundreds of species tens of species 9

Tundra 10

Boreal Forest 11

Conifer Forests • Boreal Forest - Northern Conifer Forest v • Taiga - Northernmost edge of boreal forest v • Broad band of mixed coniferous and deciduous trees between 45° and 60° N latitude. Species-poor. Harsh climate limits productivity and resilience. Temperate Rainforest v Wettest portion of coniferous forests of Pacific Northwest. 12

Temperate Deciduous Forests 13

Grasslands (Steppe) 14

Deserts 15

Tropical Seasonal Forests 16

Tropical Rainforests 17

AQUATIC BIOMES • • • Saltwater ecosystems cover vastly more total area and contain much greater volume of water than all freshwater bodies combined. Aquatic ecosystems are influenced by light penetration (depth), salt content and nutrients. v For lakes and streams, also influential are adjacent terrestrial ecosystems. For coral ecosystems, temperature also is limiting 18

Light Penetration 19

How do biomes change through time? 20

Temperature and moisture have varied Biomes 3. 5 ky in the past 21

North America 9 ky in the past 22

present vegetation and – 18 ky 23

Biomes 28 ky in the past 24

If change is “natural” why should we be concerned about modern climate change? 25

What would we mean by “collapse”? • • • Can humans contribute to collapse? What actions and consequences would be involved? v alter temperature v alter water availability v alter ability of organisms to disperse to adjust to change v alter ability of organisms to evolve quickly Some examples 26

HUMAN DISTURBANCE • • • By some estimates, humans preempt about 40% of net terrestrial primary productivity. Temperate broad-leaved deciduous forests are the most completely human-dominated biome. Tundra and Arctic Deserts are the least disturbed. About half of all original wetlands in the US have been degraded over the past 250 years. 27