Stanley J. Zarnoch

Effects of stand development and weather on monthly leaf biomass dynamics of a loblolly pine (Pinus taeda L. ) stand

Abstract Annual leaf biomass production, monthly needle accretion and monthly needlefall were measured in an 11-to 17-year-old thinned stand of loblolly pine. Initial thinning levels were 7.8 m2 ha−1, 12.6 m2 ha−1, and 25.5 m2 ha−1 (unthinned). A light thinning was done again at Age 14. Annual variations in annual leaf biomass production and monthly variations in monthly needle accretion and needlefall were related to measured stand and weather variables. Age variations in annual leaf biomass production occurred over the 6 year study period. The variation in annual leaf biomass production was best quantified as a quadratic function of stand basal area and average weighted temperature for the months of June, July, August and September. Although stand basal area was the major determinant of annual leaf biomass production, an increase in average temperature from 24.5 to 26.5°C resulted in a 27% reduction in annual leaf biomass production. This was translated to an approximate reduction of 7.3 m2 ha−1 year−1 of stemwood. Monthly needle accretion varied little between years or with stand density. Thus, a single normalized logistic function was suitable for describing monthly needle accretion for all 6 years. Monthly needlefall was variable from year to year. Variation in needlefall was low for a period of 7 months (January 16–August 15). During this period monthly needlefall averaged from 3 to 8% of the previous years annual leaf biomass production at the beginning of the phenological year. Variation in this 7 month period was not consistently related to stand density or any of the weather variables considered in this study. Monthly needlefall from August 16 to January 15 was extremely variable. This variability was not related to stand density. The weather variable that explained most of the monthly variation in needlefall during this period was the average rain-potential evapotranspiration determined for the 2 months preceding a monthly needlefall event. Peak needlefall was found to occur 2 months earlier in a drought year than in a year when rain-potential evapotranspiration was high.

Carbon dioxide efflux from a 550 m3 soil across a range of soil temperatures

Because of scaling problems point measurements of soil CO2 efflux on a small volume of soil may not necessarily reflect an overall community response. The aim of this study was to test this hypothesis in the Biosphere 2 facility and achieve the following broad goals: (1) investigate soil net CO2 exchange‐temperature relationship at the community level; (2) compare soil net CO2 exchange at the community level to the traditional sample point estimates of CO2 efflux scaled up to the community level; (3) evaluate the usefulness of a facility such as Biosphere 2 for conducting community level experiments for studying response to a climatic perturbation under controlled environmental conditions. A 550 m 3 volume of soil with 282, 15 cm tree stumps was enclosed at the Biosphere 2 Center and warmed from 10 to 25 8C over a period of 34 days. Net CO2 exchange from this community was measured at various points on the soil surface with 78.5 cm 2 chambers and for the whole community using each of the three bays at Biosphere 2 Center as a closed system. Soil CO2 efflux rates obtained by point measurements showed tremendous variability from location to location. At the community level and with point measurements, net CO2 exchange increased exponentially with increasing soil temperatures. Q10 values from both the point and community level measurements ranged from 1.7 to 2.5. Scaling of point measurements by soil surface area and time overestimated community rates by 36% revealing some of the limitations of point measurements. This experiment demonstrates how Biosphere 2 facility could be used to study behavior of individual components and measure responses at the community level and test our capacity to scale point in time and space measures of community processes to the community level. # 2002 Elsevier Science B.V. All rights reserved.

Hydrological components of a young loblolly pine plantation on a sandy soil with estimates of water use and loss

Fertilizer and irrigation treatments were applied in a 7- to 10-year-old loblolly pine (Pinus taeda L.) plantation on a sandy soil near Laurinburg, North Carolina. Rainfall, throughfall, stemflow, and soil water content were measured throughout the study period. Monthly interception losses ranged from 4 to 15% of rainfall. Stemflow ranged from 0.2 to 6.5% of rainfall. Rainfall, leaf area index (LAI), basal area (BA), and the interactions of rainfall with LAI or BA influenced prediction models of throughfall, but not stemflow, on a stand level. We found significant differences due to the effects of treatments in the soil water of the top 0.5- and 1-m soil layers by the beginning of the second growing season and throughout the remainder of the study period. Average daily water use and loss from a 1-m soil layer reflected the low water-holding capacity of the sand. Soil water in a 1-m layer was rapidly depleted to within 10% of available water during periods of little or no rainfall. Irrigation did not significantly affect productivity and created a greater potential for loss of water to drainage below 1 m. On the basis of Zahners [1966] method of soil water depletion in a sandy soil under forest cover, total drainage to below l m was 55% of evapotranspiration in unirrigated plots and 150% of evapotranspiration in irrigated plots.

Sampling and estimation procedures for the vegetation diversity and structure indicator

The Vegetation Diversity and Structure Indicator (VEG) is an extensive inventory of vascular plants in the forests of the United States. The VEG indicator provides baseline data to assess trends in forest vascular plant species richness and composition, and the relative abundance and spatial distribution of those species, including invasive and introduced species. The VEG indicator is one of several sets of measures collected by the Forest Inventory and Analysis (FIA) Program of the USDA Forest Service to assess forest health. This document describes the sampling design, field data collection methods, primary output objectives, and estimation procedures for summarizing FIA VEG data.

Heritability of first-order lateral root number in Quercus : implication for artificial regeneration of stands

Natural regeneration of oak (Quercus) species in the USA has been easy to obtain on the lower quality xeric sites (site index ⁤20 m at age 50) by developing advanced oak reproduction before stands are harvested. This approach has not been successful with Q. rubra, Q. pagoda, or Q. alba growing on highly productive river bottom, cove or other mesic sites (site index ⁥23 m at age 50) because developing seedlings are overtopped by initially faster-growing and more shade-tolerant competitor species common on these sites. Artificial regeneration to increase percentages of these three valuable multiple-use species in specific stands has not been satisfactory because of limitations imposed by planting stock quality and by the traditional technology used to manage newly established stands. After the number of first-order lateral roots (FOLR) produced by an individual seedling was shown to be a highly heritable trait, artificial regeneration trials were started by the USDA Forest Service’s Institute of Tree/Root Biology. A nursery fertility protocol was developed that could reliably and consistently produce seedlings of specific sizes. Thereafter, a seedling evaluation system was developed utilizing the parameters of FOLR, root collar diameter (RCD), and height (HT) for selecting seedling for outplanting. On mesic sites, survival and early growth for Q. rubra has been very good, with height growth of 4–5 m in 3–8 years. Trials are now being conducted with Q. pagoda and Q. alba. Methods for developing evaluation systems for oak species grown in nurseries under conditions different than the ones used in this study are discussed.

Logging utilization in Idaho: Current and past trends

A study of commercial timber-harvesting activities in Idaho was conducted during 2008 and 2011 to characterize current tree utilization, logging operations, and changes from previous Idaho logging utilization studies. A two-stage simple random sampling design was used to select sites and felled trees for measurement within active logging sites. Thirty-three logging sites and 815 felled trees were measured. Results of the 2008/2011 study indicated that harvesting efforts removed 1,011 cubic feet (cf) of timber volume from growing stock for every 1,000 cubic feet (mcf) delivered to the mill, created 24 cf of growing-stock logging residue, and that 13 cf of non-growing-stock (stump wood and tops above 4 inches diameter outside bark (dob)) were delivered to the mill. This compared to 1,086 cf of growing-stock removals that created 95 cf of growing-stock logging residue and utilized 9 cf of non-growing-stock per mill-delivered mcf in a 1990 study. This study confirmed two long-term timber harvesting trends in Idaho: declining diameter at breast height (dbh) of harvested timber, and declining amounts of logging residue generated per unit of mill-delivered volume.

The effect of fallow on Longidorus americanus, a nematode associated with stunting of loblolly pine seedlings in Georgia, USA

Stunting of loblolly pine (Pinus taeda L.) seedlings, caused by Longidorus americanus, has been a problem at a Georgia (USA) nursery. Field and growth chamber studies were conducted to determine the survivability of the nematode in fallow nursery soil. The population density of L. americanus decreased rapidly in the upper 15 cm of soil in fallow field plots during the first 101 days and the nematode was not detected after 263 days. Bioassays subsequently failed to detect the nematode in the upper 30 cm of soil in fallow plots on days 263 and 365. Population densities also decreased rapidly in fallow soil during the initial 130 days of the growth chamber study and the nematode was not detected at days 334 and 427, or in subsequent bioassays. Longidorus americanus does not survive well in the upper 15-30 cm of nursery soil in the absence of a host, and the use of fallow may be an acceptable alternative to pesticides for the management of this nematode.

Least Tern (Sternula antillarum) Population Response to Water Levels on Cheyenne River and Oahe Reservoir, South Dakota, USA

Abstract. Consideration of annual population count data, stream flows, water levels, and nesting habitat availability over a 29-year period suggest that Least Terns (Sternula antillarum athalossos) nesting along the Cheyenne River and Oahe Reservoir in South Dakota, USA, select areas primarily in response to reservoir water levels early in the breeding season. Generalized linear models were selected in an information-theoretic framework and showed important relationships between adult Least Tern numbers and reservoir levels, as well as a negative long-term temporal trend in both survey areas. Reservoir levels alone could not account for the temporal trend. The number of adult Least Terns on the Cheyenne River was positively correlated (R = 0.668) with mean May reservoir water levels—a more important relationship than that between adult numbers and river levels. The number of adults on the Oahe Reservoir was negatively correlated (R = -0.573) with mean May reservoir water levels. Numbers of adults on the Cheyenne River and on Oahe Reservoir were negatively correlated (R = -0.684), suggesting that birds may interact as one population across the two areas. This information should help managers to consider ecological relationships among segments of the Least Tern population on the Missouri River and its tributaries and options for managing Least Terns on the Cheyenne River, Oahe Reservoir, and elsewhere on the Missouri River system.

Influence of Tylenchorhynchus ewingi on growth of loblolly pine seedlings, and host suitability of legumes and small grains

Tylenchorhynchus ewingi, a stunt nematode, causes severe injury to slash pine seedlings and has been recently associated with stunting and chlorosis of loblolly pine seedlings at some forest tree nurseries in southern USA. Experiments confirmed that loblolly pine is a host for T. ewingi, and that the nematode is capable of causing severe damage to root systems. Initial population densities as low as 60 nematodes (100 cm3 soil)−1 were sufficient to damage the root systems of loblolly pine seedlings. Populations of T. ewingi increased on pine from two- to 16-fold, depending on the initial population density. Evaluations of various cover crops used in southern forest tree nurseries indicated that legumes, rye and several varieties of sorghum were excellent hosts for T. ewingi. Other small grains such as ryegrass, oats and wheat were poorer hosts. A cultivar of pearl millet was a non-host for T. ewingi, and a cultivar of brown top millet appeared to be either a very poor host or a non-host. Nurseries that have seedling production losses caused by T. ewingi should consider rotating with non-host cover crops such as pearl millet or leaving fields fallow as part of their pest management programme.

Factors Affecting Florida Scrub-Jay Nest Survival on Ocala National Forest, Florida

ABSTRACT One of the main populations of the Florida scrub-jay (Aphelocoma coerulescens), a federally threatened species, occurs on Ocala National Forest, Florida. We determined the nest daily survival rate (DSR) of 474 nests of Florida scrub-jays in stands subject to sand pine reforestation management after timber harvesting or wildfire on Ocala National Forest. We used the information-theoretic approach with logistic-exposure modeling to determine the most likely models to account for DSR for the incubation and nestling stages separately. The models consisted of 4 components (temporal, management, habitat, and helpers) with each consisting of one to several specific variables. In the incubation stage all the best models included the temporal component alone or in concert with the habitat, helpers, or habitat and helpers components. Model averaging in the incubation stage indicated support for the year and day × year in the temporal component and stand age in the habitat component. In the nestling stage, top models all included the temporal component alone or with helpers or habitat, helpers, and the interaction of habitat and helpers. Model averaging in the nestling stage showed support for the year, nest age, and to a lesser extent day in the temporal component and helpers. The management component, which consisted of no site preparation, wildfire burn, post-harvest burn, chop and seed, or seed only, had little influence on nest survival for the incubation or nestling stages. However, we identified several other management factors that may increase Florida scrub-jay populations despite having no effect on DSR. First, the proportion of Florida scrub-jay nests was significantly higher than expected in burned habitat based on habitat availability, indicating a potential preferred nesting habitat conducive to population growth. Second, incubation stage DSR with respect to stand age (habitat component) declined to stand age 10 yr and then began to increase, which may be attributed to the higher bird population in the prime habitat in the middle stand ages. The denser population may result in more competition for resources, and possibly may attract more predators, resulting in a lower DSR. Thus, although DSR may be lower at the mid-stand ages, the overall population may actually be optimal. Therefore, to increase the Florida scrub-jay population on Ocala National Forest, we recommend maintaining a mosaic of stands ≤20 yr of age and emphasizing natural reseeding and site preparation via burning.