Assessing the Effects of Canopy-derived Nutrient Fluxes on Key Soil Ecosystem

Services

Dr. Carl Rosier Delaware Environmental Institute

Define Canopy-derived nutrient flux Briefly discuss soil ecosystem services Review, results and findings from a

study where we try to connect canopy influences to soil processes

Overview

Acknowledgements A. Aufdenkampe, J. Kan, D. Levia,

and J. Van Stan S. Hicks, D. Montgomery A. Roberson and G. Rosier

Exactly what is Canopy-derived nutrient flux?

-5-15% of precipitation is absorbed by leaves and directed down plant stem

-Highly concentrated in nutrients due to leaf and stem contact

-Homogeneous distribution of nutrients at stem base

Evaporation

Throughfall

Stemflow

Interception

Canopy manipulation of precipitation and leafs leaching capacity

-10-50% of precipitation is intercepted tree canopy

-0% nutrient gain by the soil environment

-10-50% of precipitation absorbed by leaves and drips to the ground

-90% nutrient gain by the soil environment

-Heterogeneous in distribution

Canopy-derived nutrient fluxes vary: tree morphology Bark texture effects stemflow and throughfall potential

American Beech

Yellow Poplar

Canopy-derived nutrient fluxes vary: tree morphology Leaf Area effects stemflow and throughfall potential

Photo: biology.missouristate.edu/herbarium

American Beech

Yellow Poplar

Photo: biology.missouristate.edu/herbarium

Soils are a multi-functional resource that provide a range of ecosystem goods and services

(Center Ecology & Hydrology).

What is a Soil Ecosystem Service?

Recycler of Nutrients

Water purification

Medium for Plant Growth Site of Biological Diversity

Storage of Global CO2

Why do we care if the Canopy has an influence on Soil Processes?

Sequestration of global CO2 – Soils represent a significant storage reservoir of Carbon.

However, the mechanisms controlling soil potential to store Carbon are not completely known.

Understanding how individual tree species affect overall soil-C would provide greater realism of soil C-budgets for mixed species watersheds

Invasive plants – Plants can condition their home soils by controlling: organic matter turnover, nutrient cycling, water storage

These factors are tightly coupled to the organisms living in the soil

Understanding these processes increases the potential to restore native plant communities

(a) Do soils experience greater soil moisture in the presence of stemflow compared to throughfall. Is there a seasonal effect?

(b) Do ecohydrological processes influence soil respiration and what effect does this have on soil-c storage?

(c) Do soils experiencing different ecohydrological processes maintain different microbial communities?

Research Questions

Research Area: The study plot is within the Fair Hill Natural Resources Management Area (NRMA) in northeastern Maryland (39°42′N, 75°50′W)

The forest canopy is broadleaved deciduous, co-dominated by Fagus grandifolia Ehrh. (American beech) and Liriodendron tulipifera L. (yellow poplar)

Hours

0 5 10 15 20

Soi

l Moi

stur

e (%

)

0.32

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0.48

0.50

0.52

0 5 10 15 200.20

0.22

0.24

0.26

0.28

0.30

0.32

Rai

nfal

l (m

m)

0

2

4

6

8BeechPoplarRainfall (mm)

Leafout-summer Dormancy-winter

Soil Moisture:

YP AB

< 20m

3-Decagon soil moisture probes were installed at the tree bole of one-American beech (AB) and one-Yellow poplar (YP)

Decagon soil moisture probes

Leafout- AB soils gain 10% increase in soil water when compared to YP

During leafout AB soils dry quicker possibly due to root adsorption

Dormancy results in only a 3% increase in AB soil water compared to YP

Soil Respiration: Fig. (a): CO2 mineralization rates for AB and YP during four separate precipitation events.

Fig (b): YP and Fig (c); AB throughfall and stemflow quality assessed by DOC/DON and Aromaticity. Values were averaged over 8-rainfall events spanning 6-months.

Soils experiencing Stemflow maintain grater rates of CO2

Bacterial and Fungal Molecular Analysis

YP AB

Bulk Soil(0-10 cm)

< 20m

3x

DNADNA DNA

PCR

DGGE

3 trees per specie were sampled; 6-total trees

Tress were sampled at three intervals; summer, winter, and spring

DNA: extracted from soil samples using Power TM Soil DNA Kit (MO BIO Laboratories)

This yields total DNA

Polymerase Chain Reaction: Universal primers used to amplify bacteria and fungal communities

3-samples per tree at each sampling interval.Samples were pooled prior to DNA extraction

Density Gradient Gel Electrophoresis: molecular technique that uses the isoelectric point of DNA and GC content to isolate specific strands of DNA

Bacterial Community Analysis: Summer Samples

(A) The dendrogram of hierarchical cluster analysis based generated by GelCompare II software (B) DGGE banding pattern of total bacterial DNA extracted from AB, YP and Open Canopy soils.

AB and open canopy treatments maintain very similar bacterial communities

YP treatments maintain dissimilar bacterial communities suggestive that the uneven allocation of canopy resources may be influencing the heterogeneous structure of bacterial communities associated with YP trees

Fungal Community Analysis: Seasonal Samples (A)The dendrogram and DGGE banding pattern of AB soils for three seasons(B)The dendrogram and DGGE banding pattern of YP associated soils

Fungal communities associated with AB trees shift towards dissimilarity during spring

This could be the result of delayed leaf-out in some trees

Fungal communities associated with YP trees shift towards similarity during winter

This is suggestive of canopy effects on fungal communties

Summary Stemflow: alters several soil

process providing American Beech with a competitive advantage over other tree species

Throughfall: disproportionate allocation, and recalcitrant nature on throughfall inputs from Yellow Poplar drives the dissimilarity of microbial communities