How Soil Correlates with

Tree Distribution and Diversity

James Biddle

Special Thanks➔Sean McMahon➔Geoffrey Parker➔Jessica Shue ➔Ben Turner➔Laureen Echiverri ➔Dan Gustafson & Lauren Nuzzi

Outline➔Overview of Summer Work➔A Focus on Nutrients and Productivity ➔Questions and Hypothesis➔Methods➔Findings➔Conclusion and Future Directions

So What?● Is there an impact of soil nutrients on

the distribution of tree species at SERC?

● What other factors influence tree dispersal?

● Why does this matter?

The Projects●SI-GEO Soil Carbon Census●Dendrometer Band Sampling ● Innovative Photo-Based Tree

Measurement ●Weekly Micro Cores of Beech

Trees

ForestGEO Network

Sixteen Hectares. Four Hundred Forty-Eight Samples.

Collection Methods● 1-2 People in the Field● Drilling Through Mud, Clay,

Sand, Roots, Rocks

Processing Methods●Soil Collected ●Removed roots and measured

weight●Measured soil moisture●50g samples sent to STRI

Carbon Project Future●Carbon content analyzed●Spatial maps●Further analyses of tree

diversity and soil interactions

Soil Nutrient Collection Sites

SI-GEO Topography

Distribution of Moisture

Correlation Between Soil Moisture & Elevation

Technical Terms● Effective Cation Exchange Capacity (ECEC) is the

amount of exchangeable cations found on solid soil particles

● These cations are Ca, Mg, Na, and K, and many others

● Resin bags in the soil collect the nutrients floating in the soil solution instead of the solid particles

● Focusing on Calcium collected using the resin bag method

Distribution of ECEC

Distribution of Calcium

Distribution of Phosphorus

Distribution of Water pH

Distribution of Calcium and Sweetgum

Distribution of Water pH and Tulip Poplar

Distribution of ECEC and American Beech

Distribution of Water and Spicebush

Conclusions"Correlation is not causation...”

“but it sure is a hint.”- E.R. Tufte

● Many variables affecting tree distribution● Strong relationship between moisture and dispersal● Nutrients have impact, easier to see in flat areas

with consistent soil moisture

Next Steps● More complete picture of what impacts tree

dispersal with integration of soil carbon census

● Further data analysis could reveal exciting correlations

● New connections within nature● Comparisons to other Forest GEO plots

Questions?