Felix Ponder

Effects of soil compaction, forest leaf litter and nitrogen fertilizer on two oak species and microbial activity

A greenhouse study examined the effects of soil compaction and forest leaf litter on the growth and nitrogen (N) uptake and recovery of red oak (Quercus rubra L.) and scarlet oak (Quercus coccinea Muencch) seedlings and selected microbial activity over a 6-month period. The experiment had a randomized complete block design with three replications. Ammonium 15N-sulfate at 33 mg 15N kg-1 was used to quantify seedling N uptake and recovery. After 6 months, seedlings were harvested and analyzed for dry matter production, total N, 15N uptake and N derived from 15N labeled fertilizer (Ndff). Soil enzyme activity and soil microbial biomass C and N were measured as indicators of microbial activity. Soil compaction significantly decreased seedling height, dry matter production, and 15N recovery of both oak species. Significantly greater N losses were observed in compacted pots compared with the non-compacted pots. Less 15N was immobilized in the soil microbial biomass in the compacted pots than under non-compacted conditions, probably due to greater overall 15N losses in the compacted conditions. Soil compaction significantly affected microbial activity by reducing acid phosphatase. Severe soil compaction decreased young tree growth and reduced N fertilizer uptake.

Characterization of coarse woody debris across a 100 year chronosequence of upland oak–hickory forests

In most forest ecosystems, the total amount of coarse woody debris and its distribution into decay classes change over time from harvest to old growth stages. The relationship of decomposition classes to substrate quality is important to determine the contribution of woody debris to ecosystem nutrient cycling and forest development. The two objectives of this study were: (1) to determine if down dead wood (DDW) nutrient content varied with decomposition class or forest stand age; (2) to determine if DDW decomposition classes were related to indicators of substrate quality. Volume, mass, and indicators of substrate quality, such as N content and lignin:N ratio, were determined for woody debris from several decomposition classes in upland hardwood forest stands of different ages in southern Indiana, USA. Results showed a large decrease in volume and mass of DDW from recently harvested to mature stands. The dominant decomposition class shifted from Class II to Classes III and IV with increasing stand age. No Class I woody debris was found within any of the study plots. Nutrient concentration (N, S, and P) and carbohydrate fractions (soluble, hemicellulose, cellulose, and lignin) all varied significantly among certain decomposition classes, but N and P concentration and the C:N ratio were the best indicators of decomposition class. Patterns of P retention in decomposition classes suggested a strong potential for immobilization of this nutrient in woody debris. Based on substrate quality groupings, there were three distinguishable decomposition classes: Classes II and III, Class IV, and Class V.

Juglone concentration in soil beneath black walnut interplanted with nitrogen-fixing species.

Juglone concentration was measured in soils collected under a 14-year-old black walnut (Juglans nigra L.) plantation containing plots of pure walnut and of walnut mixed with either autumn-olive (Elaeagnus umbellata Thunb.) or European black alder (Alnus glutinosa (L.) Gaertn.). Juglone concentrations declined with soil depth and distance from the walnut tree. Concentrations in autumn-olive-walnut plots were statistically lower than concentrations in European black alder-walnut or pure walnut plots. The concentration of juglone in soil in European black alder-walnut plots was apparently sufficient to cause the onset of black alder mortality.

Autumn-Olive as a Nurse Plant for Black Walnut

Autumn-olive, Elaeagnus umbellata Thunb., is a promising species for planting in mixture with black walnut, Juglans nigra L. In five plantations in Missouri, Illinois, and Indiana, walnut grown in mixture with autumn-olive averaged 82% taller after 9 yr than walnut grown in pure stands. Two southern Illinois plantings were selected for more detailed study, one in a well-drained bottomland and the other on a broad upland ridge. In both areas, interplanting with autumn-olive stimulated a 134% increase in walnut height compared with walnut grown alone. Increased height of the walnut trees in mixed plantations was first apparent about 4 yr after planting, and the best group of four plots averaged more than 6.8 m tall at age 9. During the growing season, the mixed plantings are characterized by greater soil nitrogen, lower soil and air temperature, and lower soil moisture than found in the pure walnut plantings.

The effects of forest practices on earthworm populations and soil microbial biomass in a hardwood forest in Missouri

Physical changes caused by forest management practices can have a dramatic effect on the soil biota in a forest ecosystem. The effects of soil compaction associated with harvesting on earthworm populations and selected soil properties were measured in a hardwood (oak-hickory) forest in Missouri. Soils in this region of Missouri are characterized by a cherty residuum that is primarily of the Clarksville series (Loamy-skeletal, mixed, mesic Typic Paledults). Earthworms were collected from a 0‐15 cm depth each spring and fall for 2 years by handsorting and their populations determined on a per square meter basis. Two native earthworm species, Diplocardia omata and Diplocardia smithii, were identified at this site. Regardless of species, juvenile populations accounted for a major portion of the earthworms found in spring or fall. In 1995, Diplocardia ornata was the dominant species present and most affected by soil compaction. In 1996, soil compaction seemed to have a less restrictive effect on earthworms. Harvesting had no effect on either earthworm populations or biomass but had a significant effect on selected soil properties. Harvest levels had a significant negative correlation with soil moisture, soil inorganic N, and soil microbial biomass C and N. When above-ground biomass like logs and forest floor litter were removed and the soil was compacted, the standing soil microbial biomass along with soil moisture content and nutrients were reduced. Time (season of the year) had a significant effect on earthworm populations and biomass and all soil properties that were measured in both 1995‐1996. Future studies at this site might include a seasonal study on the ecology and reproduction of these native earthworm species. # 1999 Elsevier Science B.V. All rights reserved.

Fine root dynamics across a chronosequence of upland temperate deciduous forests

Following a major disturbance event in forests that removes most of the standing vegetation, patterns of fine root growth, mortality, and decomposition may be altered from the pre-disturbance conditions. The objective of this study was to describe the changes in the seasonal and spatial dynamics of fine root growth, mortality, and decomposition that occur following removal of standing forest vegetation. Four upland temperate deciduous forest stands in southern Indiana, USA were chosen for this study. The ages of the stands, as represented as the number of growing seasons since forest overstory removal, were 4, 10, and 29 years at the beginning of the study in 1995. A mature stand, about 80-100 years since last harvest, was chosen to represent the pre-harvest conditions. A combination of soil cores and ingrowth cores were used to assess stand-level rates of fine root growth, mortality, and decomposition. Results show that fine root growth increases significantly after harvesting, but declines as the stand matures. In all stands, fine root mortality and decomposition are nearly equal to or greater than fine root growth. Fine root growth in the A horizon (0-8 cm) is significantly greater than in the B horizon (8-30 cm) in the 4, 29, and 80-100-year-old stands. In the 4- and 10-year-old stands fine root growth in the A horizon peaks earlier in the year than in the B horizon. Fine root biomass recovers rapidly in these upland hardwood stands following forest removal due to high rates of fine root growth; however, the distribution of fine root growth between the A and B soil horizons differs from pre-harvest conditions during the first 10-30 years.

The influence of soil compaction and the removal of organic matter on two native earthworms and soil properties in an oak-hickory forest

Abstract Earthworms may alter the physical, chemical, and biological properties of a forest soil ecosystem. Any physical manipulation of the soil ecosystem may, in turn, affect the activities and ecology of earthworms. The effects of removing organic matter (logs and forest litter) and severely compacting the soil on native earthworm species were measured in a central USA hardwood region (oak-hickory) forest in the Missouri Ozarks (USA). Soils in this region are characterized by a cherty residuum that is primarily of the Clarksville series (Loamy-skeletal, mixed, mesic Typic Paledults). Earthworms were collected from 0–15 cm depth each spring and fall for 2 years by handsorting, and densities were determined on a per meter square basis. Two native earthworm species, Diplocardia ornata and Diplocardia smithii, were dominant on this site. Organic matter removal decreased the average individual biomass of both species. However, both species responded differently to soil compaction. Soil compaction affected D. ornata adversely and D. smithii favorably. This suggested that the degree of soil compaction was not as restrictive with respect to D. smithii (2 mm diameter) as to D. ornata (5 mm diameter). Moreover, the apparently improved soil environmental conditions resulting from the remaining organic matter in compacted soil enhanced the population and growth of D. smithii. Sampling position on the landscape affected D. ornata but not D. smithii. Soil microbial biomass C and soil microbial biomass N were decreased under soil compaction when the organic matter was removed. Other factors influencing the ecology and activity of these two species will require further study.

Effect of Soil Compaction and Biomass Removal on Soil CO2 Efflux in a Missouri Forest

Abstract Forest disturbances associated with harvesting activities can affect soil properties and soil respiration. A soda‐lime technique was used to measure soil carbon dioxide (CO2) efflux rates in clearcut plots of a Missouri oak‐hickory (Quercus spp. L.—Carya spp. Nutt.) forest 4 years after being treated with two levels of forest biomass removal and two levels of compaction, both separate and in combinations, and an uncut control. Respiration rates were measured twice a month from mid‐April through October. Soil CO2 efflux rates were significantly (p<0.001) higher in uncut control plots than in clearcut plots, but differences between biomass removal or soil compaction treatments were not significant. Soil CO2 efflux rates were positively correlated with soil temperature. The lack of difference between soil CO2 efflux rates in weed control and no weed control subplots suggests that several more years may be required for regenerating clearcut plots to produce soil respiration rates similar to those in uncut control plots.

Fertilizer Combinations Benefit Diameter Growth of Plantation Black Walnut

Abstract The diameter at breast height (dbh) growth of black walnut (Juglans nigra L.) trees in an 18‐year‐old plantation was measured over 4 years to determine the effect of nitrogen (N) and potassium (K) fertilization separately, in combination, and with and without phosphorus (P), broadcast annually at two rates. Trees in treatments containing N had significantly better dbh growth than trees in other treatments. However, doubling the application rate of 310 kg ha‐1 of N and P and 490 kg ha‐1 of K had no significant effect on dbh growth. There was a positive significant correlation for leaf N and dbh growth. The significant negative correlation between leaf P and dbh growth suggests that soil P concentrations may be less than the amount needed for accelerated dbh growth.

Seasonal variation in foliar composition of black walnut trees

Abstract Leaf samples were collected from upper and lower crown positions at three times during the 1971 and 1972 growing seasons for planted black walnut (Juglans nigra L.) trees on the Kaskaskia Experimental Forest in Hardin County, Illinois. The average dry weight of leaves was affected by crown position and time of year. Foliar concentrations of N, P, K, Ca, and Mg were affected by season, but not by crown position. The content of all elements tested and the concentrations of Ca and Mg increased with season while concentrations of N, P, and K decreased as the season progressed. Suggestions for sampling dates are given.