1. Introduction
Nonnative plant invasions may alter soil carbon cycling
and influence interactions between other native and
invasive species within a community (citation). Because
plants link the above- and belowground components of
ecosystems, combining aboveground and belowground
perspectives is essential for a more complete
understanding of the functional significance of plant
invasions (Wardle et al. 2004). For example, ecosystem
respiration in wooded areas is often dominated by soil
respiration, which accounts for 69% of this flux
(Janssens et al. 2001). In turn, soil respiration reflects
contribution from the microbiological decay of soil
organic matter as well as root and microbial activity in
the rhizosphere.
The European Black alder (Alnus glutinosa), native to
most of Europe, southwest Asia, and northern Africa, is
an increasingly widespread invasive tree in western
New York. Hosting nitrogen fixing filamentous Frankia
bacteria that increase soil nitrogen and plant availability,
Alnus glutinosa is often restricted to soils with limited
nutrient availability (Kutsch et al. 2001). Riparian
floodplain restoration along the heavily urbanized
Buffalo River in Buffalo, New York has created new
opportunities for the establishment of Alnus glutinosa.
This research study aims to document black alder’s
influence on soil microbial respiration in comparison
with surrounding grass-dominated meadow.
Research Hypotheses
I predicted that, due to symbiotic relationships between
black alder and nitrogen fixing bacteria, soil collected
from black alder patches would have higher rates of soil
microbial respiration compared to soil from the
surrounding grass-dominated meadow. In contrast, due
to the greater abundance of fine roots in the meadow
soils, I predicted that meadow soils would have greater
soil organic matter than soils from black alder patches.
RESULTS
Literature Cited
Janssens, I. A, Lankreijer H., Matteucci G., Kowalski A. S., Buchmann, N., Epron, D., Pilegaard, K., Kutsch, W., Longdoz, B.,
Grunwald, T., Montagnani, L., Dore, S., Rebmann, C., Moors, E. J., Grelle, A., Rannik, U., Morgenstern, K., Oltchev, S.,
Clement, R., Guomundsson, J., Minerbi, S., Berbigier, P., Ibrom, A., Moncrieff, J., Aubinet, M., Bernhofer, C., Jensen, N.,
Vesala, T., Granier, A., Sculze, E. D., Lindroth, A., Dolman, A. J., Jarvis, P. G., Ceulemans, R., Valentini, R. (2001)
Productivity over shadows temperature in determining soil and ecosystem respiration across European forests. Glob
Change Bio .7:269-278.
Kutsch, L.W., Staack, A., W, J., Middlehoff, U., Kappen, L. (2001) Field measurements of root respiration and total soil
respiration in an alder forest. New Phytologist. 150:157-168.
Reeuwijk, L.P van. (2002) Procedures for soil analysis. 6th edition. Technical Paper/International Soil Reference and
Information Centre, Wageningen, The Netherlands.
Wardle, A. D., Bardgett, D. R., Klironomos, N. J., Setala, H., Putten, H. van der. W., Wall, H. D. (2004) Ecological linkages
between aboveground and belowground biota. Science 304:1629-1633.
Materials/Methods
Site Description
Seneca Bluffs Natural Habitat Park began initial habitat restoration activities in 2004 by Erie County DEP. It currently consists of 15
acres of riparian floodplain and upland meadow, including over 760 meters of Buffalo River shoreline. Though recently restored,
Seneca Bluffs has been invaded by Alnus glutinosa which has established scattered patches in both the floodplain and upland
meadow communities. Other abundant species at this site include cottonwood (Populus deltoides), oak (Quercus spp.), goldenrod
(Solidago canadensis) and the invasive species mugwort (Artemisia vulgaris), Japanese knotweed (Fallopia japonica), and
common reed (Phragmites australis).
Soil samples were collected from Seneca Bluffs Natural Habitat Park, Buffalo, NY (Figure 2) in an older tall grassland field at 42
51.437 Latitude, and 78 51.478 Longitude. Samples were collected at approximately 1 meter in depth.
Soil collected around the rhizospheres of black alder clusters, and soil collected around perennial grasses , labeled Meadow,
(Figure 1) were sieved separately and appropriately labeled and refrigerator stored.
Soil respiration (gCO2/gSoil/second) between approximately 5g samples of each were measured using a portable photosynthesis
analyzer fit with a small cuvette (LI-6400XT, Li-Cor Environmental Corp., Lincoln, NE, USA). This was done in order to highlight the
extent of respiratory influence, black alder has within nonnative habitats of Western New York, due to increased densities of
nitrogen fixing soil microbial symbiotes.
Water potential (MPa) between samples of black alder and meadow soil were measured using a Water Potentiometer (WP4C
Water Potentiameter, Decagon Devices Corp., Pullman, WA, USA) to measure gravimetric soil water content.
Wetted samples were massed and then placed in a drying oven (Binder, Asheville, NC, USA) at 60 C for 18 hours. Samples were
removed from the oven and their mass was remeasured.
Gravimetric water content was calculated as the difference between sample wet mass and sample dry mass divided by sample wet
mass (Reeuwijk 2002), collected using a muffle furnace (Cole-Parmer Box Furnace) set at 550 C for four hours.
Figure 1: European black Alder (Alnus glutinosa) cluster, surrounded
by native perennial grasses and invasive japanese knotweed (Fallopia
japonica) at Seneca Bluffs Natural Habitat Park in Buffalo, NY.
Figure 2: Seneca Bluffs Natural Habitat Park in Buffalo, NY. Consists
of approximately 15 acres of riparian floodplain along the Buffalo
River in a highly urbanized area. Habitat types range from floodplain
island, seasonally flooded wetland, forested floodplain, upland
meadow, and approximately 760 meters of shoreline.
Measuring The Invasive European Black Alder’s Influence On Soil
Microbial Respiration
Richard Rodriguez and Dr. Daniel L. Potts
SUNY Buffalo State, Department of Biology, 1300 Elmwood Avenue, Buffalo, NY 14222
4.3g 5.1g
9.85
9.9
9.95
10
10.05
10.1
10.15
10.2
Soil Organic
Matter Content
(%)
A. glutinosa and Bulk Meadow Dry Soil Sample Averages
0
0.1
0.2
0.3
0.4
0.5
0.6
Soil Respiration
(gCO2/gSoil/Seco
nd)
Black Alder Meadow Soil
Soil Respiration (gCO2/gSoil/Second) of Alnus
glutinosa and Bulk Meadow
Figure 3: Depicts the relationship between soil respiration
(gCO2/gSoil/Second) as a function of soil samples of A.
glutinosa and Meadow soil. Soil respiration rates higher in
alder samples were higher (0.523gCO2/gSoil/Second) than
meadow (0.329gCO2/gSoil/Second). P=0.11, shows a
presumption against the null hypothesis.
Figure 4: Depicts the relationship of A. glutinosa (orange)
and meadow (brown) soil organic matter content, expressed
as a percentage of mean soil mass. Rate of organic carbon
in alder samples were 9.95% compared to that of meadow at
10.14%. P=0.78 depicts no real significance in carbon
content between soil samples.
Soil Organic Matter Content (%) of Alnus glutinosa and
Meadow
Figure 5: Gravimetric water potential as a function of A.
glutinosa and Meadow soil samples soil used across
eight tests. Discussion
Filamentous nitrogen fixing bacteria such as Frankia alni found on the root systems of the
European Black Alder, make this invasive plant species influential to low quality soils
(Janssens 2001). Due to increased nitrogen cycling, higher rates of soil in soil such as
that in restorative sites like Seneca Bluffs, are expected. Possibly due in tandem with the
small sample sizes used in this study, as well as the fact that clusters of alder found were
still very young in age; there was little more than a slight difference in respiration levels
between alder and meadow soils (P=0.11) (Figure 3).
Soil water content, in addition to temperature, are significant factors controlling variability
in soil respiration. The negligible differences in soil water potential and gravimetric water
loss between alder and bulk meadow samples (Figure5) is cohesive with data collection of
soil respiration, and the slight differences seen (Figure 3). The slightly higher rates of soil
respiration within alder samples may be attributed to microbial nitrogen fixing F. alni
bacteria (Kutsch et al. 2001).
LOI (Figure 4) provided percentage rates of organic carbon within alder and meadow
samples, showing little significance in variability (P=0.78). Lower levels of organic carbon
may be attributed to soils saturated with nitrogen fixation, however further research is
needed to make this claim regarding A. glutinosa (Kutsch et al. 2001).
In summation, due to small rates of variability in the data, future studies are required
when black alder’s become more mature and prevalent within restorative areas in western
NY, to solidify the research hypothesis with higher significance and reliability.
Figure 6: Protocol for testing
soil respiration.
0.84
0.86
0.88
0.9
0.92
0.94
0.96
0.98
1
Black Alder Meadow
Gravimetric
Water
Potential
-0.28
-0.275
-0.27
-0.265
-0.26
-0.255
-0.25
-0.245
-0.24
-0.235
-0.23
Water
Potential
(MPa)
Black Alder Meadow
Gravimetric Water Potential Across A. Gultinosa and Meadow Soil
Samples
Water Potential In Black Alder And Meadow Soil samples
Figure 6: Water potential (Mpa) as a fcuntion of A. glutinosa and
Meadow soil samples used across eight tests.