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Ecosystem processes and heterogeneity

Ecosystem processes and heterogeneity. Landscape Ecology. Today. Global NPP Lake position Moose impacts. Questions/Comments. Ecosystem processes. What do we mean? Energy Matter Carbon Nutrients. Spatial Heterogeneity in ecosystem process .

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Ecosystem processes and heterogeneity

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  1. Ecosystem processes and heterogeneity Landscape Ecology

  2. Today • Global NPP • Lake position • Moose impacts

  3. Questions/Comments

  4. Ecosystem processes • What do we mean? • Energy • Matter • Carbon • Nutrients

  5. Spatial Heterogeneity in ecosystem process • What can cause ecosystem processes to vary spatially? • Temperature • Moisture • Topography

  6. What factors affect NPP? • Climate • Temperature • Light • Precipitation • Nutrients

  7. Where is global marine NPP highest? • Why?

  8. Where is global terrestrial NPP highest? • Why?

  9. Paradox… • How do the factors that drive NPP differ between marine and terrestrial ecosystems? • the basic processes of plant photosynthesis are the same for terrestrial and marine/aquatic plants • the key factors must be the physical and chemical properties of the environments in which plant growth occurs, • or the carbon allocation and life history dynamics of the plants themselves.

  10. Marine NPP • “Marine NPP was a major driver of the preindustrial cultures and economies of civilizations in the higher latitudes, and is still a major driver of the global fishing industry” • Driven by: • Nutrients – upwelling • Geology

  11. Terrestrial NPP • “The most remarkable feature of the terrestrial NPP distribution is that it is the opposite of the pattern of marine NPP” • Driven by: • Climate? • Why not nutrients?

  12. Nutrients in Tropics • Are the tropics a good place for agriculture? • The basic processes of soil weathering have several inevitable consequences that result in a decline in soil fertility, and thus in the resources available to support plant growth and NPP over time as soils age. • All of these processes occur most rapidly in the tropics.

  13. Global Nutrient Content

  14. “Why should marine productivity be positively correlated with the availability of mineral nutrients in the oceans and the adjacent continents, while the productivity of the plants growing in the soil on those continents is inversely correlated with nutrient availability?”

  15. Conclusions • In fact, the highest short-term rates of NPP (eNPP) apparently occur in temperate and boreal forests. • These patterns of forest productivity are consistent with the global distribution of soil fertility • as well as the productivity of certain types of crops • and the standardized economic value of agricultural production

  16. Why is might our current paradigm about NPP wrong? • Hard to measure NPP • Satellites measure green leaves, not necessarily carbon that goes into wood.

  17. Landscape Position and Lakes • What factors influence the ecosystem functions of a lake? • Geology • Size/Depth • Climate • Terrestrial inputs • What about the spatial arrangement of lakes can influence functions? • Geology • Climate • Hydrologic connectivity

  18. What type of ecosystem properties could be influenced?

  19. How to test? • Observational study..

  20. Conclusion • Many factors change with position • Ionic composition • Biota • Size • Primary Production

  21. Species and ecosystem function • How do species influence ecosystem function?

  22. Effects of Moose Browsing on Vegetation and Litter of the Boreal Forest, Isle Royale,Michigan – McInnis et al. Spatial patterns in the moose-forest-soil ecosystem on Isle Royale, Michigan USA – J. Pastor et al.

  23. Background • Landscape heterogeneity affects population dynamics and movement. • Animals can alter ecosystem function due to their behavior. • Ecosystem engineer? • Large herbivores could have large impacts: • Large home ranges. • Eat a lot. • But only what is tasty.

  24. Background cont. • With selective feeding, herbivores can affect species composition, nutrient cycling, etc. • Obvious on a local scale. • Can herbivores alter ecosystem function at the scale of their home range, or of a valley?

  25. Effects of Moose Browsing on Vegetation and Litter of the Boreal Forest, Isle Royale,Michigan • Observations: • Herbivores change the structure, biomass, production, and species composition of vegetation in heavily browsed or grazed areas • Questions: • Results:

  26. Effects of Moose Browsing on Vegetation and Litter of the Boreal Forest, Isle Royale,Michigan • Observations: • Questions: • What are the effects of browsing upon the biomass and production of trees, shrubs, and herbs? • Does browsing alter species composition of the vegetation? • Do changes in species composition affect the quality and quantity of litterfall in browsed areas? • Results:

  27. What are the effects of browsing upon the biomass and production of trees, shrubs, and herbs?

  28. Does browsing alter species composition of the vegetation?

  29. Effects of Moose Browsing on Vegetation and Litter of the Boreal Forest, Isle Royale,Michigan • Observations: • Questions: • What are the effects of browsing upon the biomass and production of trees, shrubs, and herbs? • Does browsing alter species composition of the vegetation? • Do changes in species composition affect the quality and quantity of litterfall in browsed areas? • Results: • Higher biomass, alters species composition, …

  30. Spatial patterns in the moose-forest-soil ecosystem on Isle Royale, Michigan USA – J. Pastor et al. • Observations: • Hypotheses: • Results:

  31. Spatial patterns in the moose-forest-soil ecosystem on Isle Royale, Michigan USA – J. Pastor et al. • Observations: • Moose preferentially forage on aspen and avoid conifers. • Hypotheses: • If moose browsing causes a shift in dominance from hardwoods to conifers across adjacent areas, we should expect corresponding changes in soil nutrient availability over the landscape. • Results:

  32. What was the study about? • Examine the large-scale landscape distribution of moose browsing intensity in relation to plant community composition and size structure, as well as soil nitrogen availability. • Do moose control plant community composition and soil nitrogen at large scales?

  33. What did they measure? • Available browse. • Annual consumption by moose. • Soil nitrogen availability.

  34. They tested three models • Random • Short-range autocorrelation • Higher order of regularly arranged patterns

  35. What would these models look like? • Random • No autocorrelation – constant variance • Short-range autocorrelation • Low-variance at short distances • Higher order of regularly arranged patterns • Low-variance at short distance and low-variances at large distances as well.

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