1. The ecology and management of Brazil nut trees (Bertholletia excelsa) in Amazonia Bill Rucker, Department of Environmental and Plant Biology, Ohio University, Spring 2015 The ecology and management of Brazil nut trees ( Bertholletia excelsa ) in western Amazonia Bill Rucker, M.S. Candidate, Environmental and Plant Biology, Ohio University, Spring 2015 https://thebrazilnutstory.wordpress.com /

2. Brazil nut : introduction Important non-timber forest product (NTFP)  Second to rubber as leading NTFP commodity  Only commercially harvested nut gathered in the wild  ca. 110 tons harvested annually  Provides income to thousands of families  Exported since mid-17 th C.; harvests increased greatly since mid-19 th C.

3. Range and extraction of Brazil nut trees in Amazonia Peres et al. 2003  Locus of Brazil nut collection shifted from east to west  Diversification of distribution  Formation of extractivist reserves in the 1990s

4. Bertholletia excelsa biology  Emergent tree 40-50m height; up to 15m dbh  Some of oldest trees in rainforest; up to ~1600 y  Pollinated by Euglossinae bees (orchid bees) Bees need relatively undisturbed habitat Bees are non-social, so hives won’t work  Fruits dispersed by the agouti (Dasyprocta spp.) Fruits remain dormant 12-18 months – predation, fungi Scatter-hoarding behavior

5. 2 major questions guiding research 1) Is there enough regeneration for stable populations? What is the spatial distribution and population structure? o Random, clumped, regular? o Size structure - relative number adults / immature? What are the most important drivers of dispersal and establishment? o agouti scatter-hoarding behavior – predation / dispersal o Do human harvesting levels impact regeneration? 2) What factors influence fruit production / seed fate? Abiotic / biotic (human, agouti, and plant) Can silvicultural treatment improve nut production?

6. Spatial distribution and population structure Summary of findings:  Distribution at Pinkaití, Pará, Brazil (both graphs from Peres and Baider 1997) never commercially harvested highly clumped across ~950 ha (2 groves) across landscape (1.3 trees/ha) random within grove (4.8-5.1 trees/ha) mean nearest neighbor distance (20.8 ± 10.6 m) 28.5 ha site overlapping a grove, all trees >10cm dbh  Highly variable distributions reported elsewhere 0.2 – 26 trees/ha uncertainties in sampling data and extrapolation density / crown diameter relationships

7. Spatial distribution and population structure Size structure – harvested vs. unharvested stands  Pinkaití – never commercially harvested / little agouti hunting  dominance in <40 cm dbh  many large ones (80-130 cm dbh)  at odds with classic negative exponential curve in size structure Pinkaití, Pará, Brazil Xapurí, Acre, Brazil  Xapurí – commercial harvest, hunting? dominance in <40 cm dbh relatively few larger sizes conforms to negative exponential curve 84% of trees <40 cm dbh found in small canopy gaps (Peres and Baider 1997)

8. Spatial distribution and population structure Is Bertholletia recruitment gap dependent?  El Tigre, Riberalta, Bolivia Seedlings (<1.3 m height) in understory and gaps Saplings (>1.3 m height) only in gaps >95 m 2 Sapling density - positive correlation with gap size and light intensity (GSF) Myers et al. 2000

9. Spatial distribution and population structure  Filipinas, Acre, Brazil 420 ha harvested since 1940s “open forest” no groves, ± random 1.35 trees/ha size structure similar to Pinkaití (unharvested) mean nearest neighbor distance = 34.3 ± 22.5 m What’s Going On? (Both graphs from Wadt et al. 2005)

10. Spatial distribution and population structure 1) To what extent is topographic pattern determining distribution? Pinkaití vs. Filipinas locations 2) How does Bertholletia respond to “open” light environment / gap dependence? 3) Do centuries-old and more recent harvesting / cultivation activities create “anthropogenic forests” favoring groves of Bertholletia? AC Jakovac

11. Agouti dispersal / seed fate (Peres et al. 1997) Seed removal studies  Pinkaití – removal only (fate unknown) overall seed removal wet season (91%) > dry season (79%) within-crown ≈ outside-crown within season within cluster removal >> outside cluster (control)  Lago Uauaçu – buried intact seeds wet season 74% >> dry season 38% seeds buried at greater distances in the dry season (Haugaasen et al. 2010)

12. Agouti dispersal / fruit fate  Problems with seed removal studies; e.g. predation, fungi  Fruits can sit on the ground for months w/o rotting  Only humans and agoutis can open with some skill Moving to gaps with cover ?? (both graphs Haugaasen et al. 2012)

13. Tree-level studies of variance in fruit production  Fruit production factors crown vine load trunk vine load crown position crown form dbh Wadt et al. 2005  Filipinas in trees < 50 cm dbh, dbh explains more fruit production variance in trees > 50 cm dbh, crown form and crown vine load explain more fruit production variance

14. Do crown liana loads reduce fruit production? Observational study  fruit production is higher for trees with <25% liana loads  both mean number of fruits and fresh weight of nuts reduced with >25% liana loads (graphs not shown)  crown form is negatively affected by increasing crown liana loads (both graphs from Kainer et al. 2006)

15. Can liana cutting improve fruit production? Experiment: 10-year liana-cutting  after ~5 years, trees w/ cut lianas increase in fruit production  trees w/ more than 75% crown liana load improved crown form and decreased mortality Kainer et al. 2014

16. Conclusions 1) Bertholletia excelsa trees may be clustered on a landscape scale into groves, but are more randomly distributed within a grove; 2) trees are likely gap-dependent particularly during the growth transition from seedling to sapling stages; 3) agouti interactions with Brazil nut fruits and nuts are complex spatially and temporally and are strongly influenced by season; and 4) heavy crown liana loads decrease fruit production and cutting can improve fruit production and crown form.