Dataset

Database Code

SP018

Title

Influence of microclimate gradients on soil characteristics within tree-fall gaps in the Andrews Experimental Forest, 1997

Abstract

This was the second 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 present study compares 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 third study expanded the number of variables studied and sampling intensity. By using the same grid system as Dr. Andy Gray in his vegetation survey work, we were able to relate below-ground processes with above-ground vegetation. Soil properties in eight, 7 year-old tree-fall gaps were compared with soils in the surrounding old-growth Douglas-fir forest. Soil characteristics were measured along two transects; one running north and south and the other east and west. This study was an extension of one done two years earlier by Shirley King (see Gap1 - study code SP017). In that study, there were significant differences in soil properties not only between soils collected in and out of gaps but also by orientation within the gap. More specifically, soils in the north end of the larger gaps were significantly different from those in the south. This study was designed confirm the previous findings that soils within gaps were different than those in the surrounding forest. In addition, we wanted to determine if there were also E/W differences. If there were none, then we could conclude that microclimate gradients were effecting these soils because the microclimate gradient along E/W transects should be much less than that found along N/S transects. We chose to measure soil characteristics at 2-meter intervals using this same basic design used by Shirley King in the Gap1 study. E/W and N/S transects were established in all of the gaps that were studied in Gap1 with the transects extending one radius into the surrounding forest.

Keywords

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

Date begin

1997-07-01

Date end

1997-07-24

Principal Investigator

Robert P. Griffiths

Entities

1. SP01801

1. SP01801 - Attribute list

Attribute definitions

B_GLUC

Beta-glucosidase activity (dry weight basis)

DENIT

Denitrification potential (dry weight basis, as N)

DIRECTN

Direction: 0 = E-W, 1 = N-S

FLDRESP

Field respiration rates

GAPNUMBR

Site designator

GAPSIZE

Gap diameter in meters

IN_OUT

1 = out of gap, 2 = in gap

LABRESP

Laboratory respiration rates (dry weight basis, as C)

LITTER

Litter depth in cm

LOCATION

Sampling location along transect

MOIST

Percent moisture

ORIENTN

Orientation E-W = east to west; N-S = south to north (explicit)

PH

Soil ph

QUAD

1=Eout; 2=Ein; 3=Wout; 4=Win; 5=Nout; 6=Nin; 7=Sout; 8=Sin

ROOTS

Amount of live roots found in cores (dry weight basis)

SECTION

Compass direction from center of gap (explicit)

SOILTEMP

Soil temperature measured with Licor

SOM

Soil organic matter

TOTALMAT

Percentage of core containing mycorrhizal mats