# Influence of microclimate gradients on soil characteristics within tree-fall gaps in the Andrews Experimental Forest, 1997 ## 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 - **Temporal coverage:** 1997-07-01 to 1997-07-24 - **Principal Investigator:** Robert P. Griffiths ## Data Entities 1. SP01801 ## Entity 1: SP01801 ### Attribute list - **GAPNUMBR** — numeric(1.000000), range 110.0000 210.0000, number Site designator - **GAPSIZE** — numeric(1.000000), range 10.0000 50.0000, meters Gap diameter in meters - **LOCATION** — numeric(1.000000), range 1.0000 50.0000, number Sampling location along transect - **DIRECTN** — numeric(1.000000), range 0.0000 1.0000, number Direction: 0 = E-W, 1 = N-S - **ORIENTN** — varchar, freetext Orientation E-W = east to west; N-S = south to north (explicit) - **QUAD** — numeric(1.000000), range 1.0000 4.0000, number 1=Eout; 2=Ein; 3=Wout; 4=Win; 5=Nout; 6=Nin; 7=Sout; 8=Sin - **SECTION** — varchar, freetext Compass direction from center of gap (explicit) - **IN_OUT** — numeric(1.000000), range 1.0000 2.0000, number 1 = out of gap, 2 = in gap - **MOIST** — numeric(0.100000), range 10.0000 60.0000, percent Percent moisture - **SOILTEMP** — numeric(0.100000), range 10.0000 20.0000, degrees Celsius Soil temperature measured with Licor - **SOM** — numeric(1.000000), range 10.0000 90.0000, percent Soil organic matter - **LITTER** — numeric(1.000000), range 0.0000 20.0000, centimeters Litter depth in cm - **TOTALMAT** — numeric(1.000000), range 0.0000 100.0000, percent Percentage of core containing mycorrhizal mats - **PH** — numeric(0.010000), range 4.0000 7.0000, pH units Soil ph - **ROOTS** — numeric(0.010000), range 0.0000 12.0000, grams Amount of live roots found in cores (dry weight basis) - **FLDRESP** — numeric(0.100000), range 0.0000 50.0000, grams per square meter per day Field respiration rates - **LABRESP** — numeric(0.010000), range 0.0000 10.0000, micrograms per gram per hour Laboratory respiration rates (dry weight basis, as C) - **B_GLUC** — numeric(0.010000), range 0.0000 1.0000, micromoles per gram per hour Beta-glucosidase activity (dry weight basis) - **DENIT** — numeric(0.001000), range 0.0000 7.0000, nanograms per gram per hour Denitrification potential (dry weight basis, as N) ## 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