Dataset

Database Code

SP019

Title

Influence of tree-fall gaps on soil characteristics in the Andrews Experimental Forest, 1999

Abstract

This is the third and final study in a series of tree-fall gap studies conducted at the HJA addressing the effects of tree-fall gaps on forest soil characteristics. The first looked at the effects of gap size on changes in soil carbon cycling within the gap along N-S transects. The second compared the effects of gaps on soil properties along both N-S and E-W transects to better differentiate between microclimate and vegetation effects within the gaps. The current study expands the number of variables studied and sampling intensity. By using the same grid system as Dr. Gray in his vegetation survey work, we are able to relate below-ground processes with above-ground vegetation. Soil properties in two large 9 year-old tree-fall gaps were compared with soils in the surrounding old-growth Douglas-fir forest by intensive sampling of a circular grid that extended 12 m into the forest. This study was designed compare below-ground soil properties with above-ground vegetation and coarse woody debris distribution patterns using three-dimensional response surfaces and to compare soil properties in and outside the gap. To accomplish this goal, samples were collected along a grid already established by Gray, A.N., and Spies, T.A. (1996) designed to study vegetative succession in tree-fall gaps of varying sizes. We chose to measure soil characteristics at 4-meter intervals using the Gray/Spies grid design. The sample grid was essentially a circle centered within the gap. The sample grid was expanded 12 meters into the surrounding forest so that comparisons could be made between soils within the gap and those in the forest. During the same summer that the soils work was done, Dr. Gray and his students conducted studies of vegetation and coarse woody debris distribution patterns within these same gaps, generating GIS data layers which could be used to directly compare with our soils data.

Keywords

disturbance; inorganic nutrients; soil; forests; canopy gaps; Long-Term Ecological Research (LTER); disturbance; inorganic nutrients

Date begin

1999-06-25

Date end

1999-07-18

Principal Investigator

Robert P. Griffiths

Entities

1. SP01901

1. SP01901 - Attribute list

Attribute definitions

AIRTEMP

Air temperature measured with Licor

B_GLUC

Beta-glucosidase activity (dry weight basis)

DENIT

Denitrification potential (dry weight basis, as N)

EAST

E-W position on grid with 0=center, negative #s to the west and positive numbers to the east

E_WQUAD

1=Eout; 2=Ein; 3=Wout; 4=Win

FLDRESP

Field respiration rates

GAPNUMBR

Site designator

GAPSIZE

All are 50 meters across

GAUT

Percentage of core containing mycorrhizal mats like those of the genus Gautieria

HYSTER

Percentage of core containing mycorrhizal mats like those of the genus Hysterangium

IN_OUT

1 = out of gap and 2 = in gap

LABRESP

Laboratory respiration rates (dry weight basis, as C)

LIGHT

Amount of light measured with licor

LITTER

Litter depth in cm

MOIST

Percent moisture

NORTH

N-S position on grid with 0=center, negative #s to the south and positive numbers to the north

N_SGAP

N = locattions within the grid to the north of center line and S = those to the south

N_SQUAD

5=Nout; 6=Nin; 7=Sout; 8=Sin

SOILTEMP

Soil temperature measured with Licor