Diversity of forest structure: within and among forest

1. Diversity of forest structure: within and among forest • General characteristics of tropical humid forests and the vertical gradient • Horizontal resource heterogeneity generated by treefall gaps • Diversity among forests in relation to hydrology and soil nutrients • Succession and forest types

2. What characterize today’s tropical rain forest angiosperms? • Tall trees, multi storied closed forests • Medium to large leaves with entire margin and drip tips • Animal-dispersed large seeds for mature forest species • Lianas (often with palmately veined leaves) • Cauliflory

3. Cauliflory (Browinia macrophylla and Theobroma cacao)

4. Profile diagram and life forms of free standing plants: vertical niches? Emergent trees Canopy trees Subcanopy trees Understory - shrubs - herbs

5. Vertical light gradient: Light intensity decreases exponentially as a function of cumulative total leaf area index From Yoda, K. (1974) Three dimensional distribution of light intensity in a tropical rain forest of west Malaysia. Japanese Journal of Ecology 24: 247-254 Also – Kira, T (1978) in Tropical trees as living systems. Eds. P.B. Tomlinson and M. H. Zimmermann. Cambridge University Press.

6. Trees differ in patterns of leaf display. (Kitajima et al. 2005)

7. Lambert-Beer law of light extinction was applied to canopy by Monsi & Saeki (1954): I/I0 = - ln (k *cumulative LAI) Where k = extinction coefficient, which is a slope in semi-log plot. Application to individual tree crowns Kitajima, K., Mulkey, S. S., Wright, S. J. 2005. Variation in crown light utilization characteristics among tropical canopy trees. Annals of Botany 95: 535-547.

8. Vertical niche stratification among antwrens

9. Tropical forests • High diversity of woody plants (trees and woody vines) • High diversity of epiphytes • High habitat heterogeneity with height • Many plants with animal dispersed fruits • Many frugivorous animals • High diversity of climbing, flying or gliding vertebrates (gliding frogs, lizards, snakes, lemurs, ants, etc.)

10. Niche partitioning among non-flying mammals Day Day and Night Night

11. Morphological Diversity • Plants • Height: canopy trees, treelets, shrubs, herbs, vines • Rooting: terrestrial, epiphytes, hemiepiphytes • Stems: woody, herbaceous, spines, barks, • Root type: bole, buttress, prop roots, pneumatophores • Flowering: terminal, cauliflory • Animals • By locomotion: flying, gliding, climbing, walking, crawling • Food types: fruigivory, granivory, folivory, nectivory, insectivory, carnivory, omnivory.

12. Liana: woody vine • common in tropical wet forest • up to 40% of the canopy surface • compete with trees • very fast growth • problem in management after selective logging

13. Buttress of tropical trees

14. Prop roots and pneumatophores of mangroves

15. Tropical clibmer/epiphyte, Monstera deliciosa

16. Prop roots of a palm (monocot without true secondary growth)

17. Monocot vs. Dicot • Monocotyledonous plants are a branch nested within branches of dicotyledonous plants • Monocot spp. include grasses, bamboos, sedges and palms. • Monocots cannot exhibit secondary growth. • Some monocots are semelparous (= single reproduction in lifetime)

18. Palms: single meristem for height growth. Some, including Corypha , die after a single flowering

19. Stem cross section: Monocot vs Dicot Which can do secondary growth(diameter increase)?

20. Cork (outer bark) Secondary Phloem Temperate trees have annual rings, but most tropical trees don’t! Annual ring (springwood + summerwood) Pith

21. Epiphytes are abundant in tropical wet forest (up to ½ of all vascular plants)

22. Strangler figs: a hemiepiphyte

23. Development of a strangler fig

24. Crown shyness among canopy trees of similar height (Dryobalanopsis plantation in Malaysia)

25. Sunflecks into the understory (otherwise, understory receives only 0.1-2% of sunlight)

26. Gap mosaic: disturbance creates heterogeneity

27. More light in gaps mean • More plant productivity, young leaves, flowers & fruits --> more food for animals • Regeneration chance for plant species that cannot survive in shaded understories • Germination of light and heat sensitive seeds • Higher temperature --> more activities of insects, amphibians, snakes and lizards. • More intense competition, predator-prey interactions

28. More light in gaps mean • More plant productivity, young leaves, flowers & fruits --> more food for animals • Regeneration chance for plant species that cannot survive in shaded understories • Germination of light and heat sensitive seeds • Higher temperature --> more activities of insects, amphibians, snakes and lizards. • More intense competition, predator-prey interactions

29. Area near San Carolos de Rio Negro, Venezuela

30. Seasonally flooded forests in Amazon • Igapós: swamps along the small streams in terra firme or along infertile blackwater river (leaves with high tannin and lignin concentration, and consequently low digestibility and very slow decomposition rates) • Várzea: swamps on alluvial rich soil. • Main river channel • Oxbow lakes

31. Types of succession • Primary (no previous vegetation) or secondary (following disturbance) • Aquatic (e.g., from filling of oxbow lakes to terrestrial) or totally terrestrial. • Gradual vs. simultaneous colonization of species that dominate at different stages.

32. Oxbow lake formation

33. Primary succession starts on new sandbars along the meandering river

34. Primary succession on open beach • 1-5 yrs: seedlings of pioneers colonize • 12-15 yrs: pioneers dominant, slower colonization of other trees • 35 yrs: pioneers start to die • -150 yrs: mid successional, dominance of slower growing species, about ½ the animal and plant species in the mature forest. • 200 yrs -: late successional forest • 300 yrs -: mature forest

35. Mechanism of primary succession • Gradual accumulation of nutrients • Nitrogen has to come from rain on new volcanic or post land slide soils. • Phosphorus may be highly available initially • Both may be relatively available in river deposit • Gradual replacement of species by shading of slower growing mature forest species

36. Pioneer vs. mature forest species • Pioneers: many small seeds, fast growth, early reproduction, requirement of high light • Mature forest trees: relatively large seeds, slow growth, late initiation of reproduction, ability to tolerate shade, crowns of high LAI (overlapping leaves) that cast deep shade.

37. Succession in Cocha Cashu river, Peru

38. Beach succession along a river in Papua New Guinea

39. Soil nutrient cycles: pools and flux

40. Mineral nutrient capitals: in many sites, soil holds significant nutrients.(Osborn Fig. 8.10)

41. Nutrient conservation mechanisms • Slow tissue turn-over rates (long-living leaves, long-living fine roots) • Resorption of mineral elements from senescing leaves (not for Ca and Si). • Protection of surface from nutrient leaching • Dense root mats • Association with mycorrhizae (ectomycorrhizae in some species dominant in very P poor soils) • Soil aggregation with organic compounds

42. Endomycorrhizae:association with most trees Fungal arbuscles (branched fungal hyphae inside host cortical cells) Localized penetration of fungal hyphae

43. Ectomycorrhizae: each fungus can form association with only a few tree species.

44. Does mycorrhizae help tree diversity? • Both types of mycorrhizae help phosphorus uptake. • Species that can make association with ectomycorrhizae become dominant in nutrient poor soils (Dipterocarpaceae spp. in SE Asia, Gilbertiodendron forest in Congo). • But…..not all low-diversity forests are dominated by species with ectomycorrhizal association.