Oak Areas Research Articles

Native oak retention as a key factor for the conservation of winter bird diversity in managed deciduous forests in northern Italy

Birds can serve as useful model organisms to investigate community level consequences of forestry practices. In this study we investigated the relationships between wintering bird communities and habitat and landscape characteristics of lowland managed forests in Northern Italy. This area is characterized by the spread of the black locust, an alien species that has been favored by forestry practices at the expense of natural oak forests. Birds were censused in winter by point counts in randomly selected plots of 50 m radius. We first addressed bird community–habitat relationships by means of habitat structure measurements, then we investigated bird community–landscape relationships by using GIS techniques. We used generalized linear models (GLM) to test for the effects of habitat and landscape variables on bird community parameters (namely bird species richness, diversity and abundance). Bird community parameters were influenced by oak biomass and tree age, and by oak area and core area, while the other forest habitat types showed less influence. In forest management terms, the main conclusion is that the retention of native oaks is the keyfactor for the conservation of winter bird diversity in local deciduous woods. At the habitat level black locust harvesting may be tolerated, provided that old, large, native oaks are retained in all local woodlots to preserve landscape connectivity and foraging resources. At the landscape meso-scale, large native oak patches, should be preserved or, where necessary, restored.

Patterns of mast production in pinyon and juniper woodlands along a precipitation gradient in central New Mexico (Sevilleta National Wildlife Refuge)

This paper reports on an 8-year continuing project with the Sevilleta Long-Term Ecological Research program (LTER) in central New Mexico aimed at the study of dynamics of woodland ecosystems. The study of mast production was conducted at six experimental woodland sites situated across an elevational gradient of 1500–2000 m in proximity to permanent meteorological stations. The dominant woody species were Juniper monosperma, Pinus edulis, and Quercus turbinella. Functioning of arid ecosystems of the Southwest undergoes seasonal, annual and multidecadal fluctuations which link to corresponding dynamics of available moisture. Results of the 1997–2004 study show a gradual decrease in mast production of all three species at all six sites, due to a continuing drought in this period. Mast production in a given year is determined to a considerable extent by available moisture during the entire growth year, from the previous spring to the current summer. The areas of oak–pinyon–juniper woodlands with higher elevation and highest precipitation generally have the highest yield of juniper berries, pinyon nuts and acorns. The severe drought of 2001–2003 has been accompanied by a mass dying of mature pinyon pines and loss of foliage in junipers. According to our observations, there is no correlation between mast production and amount of precipitation in the current year's monsoon period (June–September). A high correlation between acorn production and non-monsoonal precipitation (October–May) was established, but no such correlation was found for juniper berries and pinyon nuts. Weather conditions (wind, temperature, and moisture) of late May are a critical factor determining the success of fertilization and subsequent mast production in all three species.

Factors and scales potentially important for saproxylic beetles in temperate mixed oak forest

The influence of environmental factors on species richness and species composition may be manifested at different spatial levels. Exploring these relationships is important to understand at which spatial scales certain species and organism groups become sensitive to fragmentation and changes in habitat quality. At different spatial scales we evaluated the potential influence of 45 factors (multiple regression, PCA) on saproxylic oak beetles in 21 smaller broadleaved Swedish forests of conservation importance (woodland key habitats, WKH). Local amount of dead wood in forests is often assumed to be important, but two landscape variables, area of oak dominated woodland key habitats within 1 km of sites and regional amount of dead oak wood, were the main (and strong) predictors of variation in local species richness of oak beetles. The result was similar for red-listed beetles associated with oak. Species composition of the beetles was also best predicted by area of oak woodland key habitat within 1 km, with canopy closure as the second predictor. Despite suitable local quality of the woodland key habitats, the density of such habitat patches may in many areas be too low for long-term protection of saproxylic beetles associated with broadleaved temperate forests. Landscapes with many clustered woodland key habitats rich in oak should have high priority for conservation of saproxylic oak beetles.

The effects of size, temperature and air contact on the outcome of heating oak fragments

The concentrations of the important oak aroma volatiles guaiacol, 4-methylguaiacol cis- and trans-oak lactone and vanillin in extracts of French and American oak heated under various conditions were measured using stable isotope dilution analyses coupled with gas chromatography-mass spectrometry. Heating resulted in marked increases in the concentrations of guaiacol, 4-methylguaiacol and vanillin, with more formed at higher temperature. Approximately twice as much guaiacol and 4-methylguaiacol and two to five times as much vanillin were formed by heating in the presence of air compared to heating under argon. Oak lactone concentration was less affected by heating. The effects of heating different sized oak pieces were investigated for French and American oak samples. Compared to heating larger oak pieces, heating smaller fragments of oak generated up to twice as much guaiacol and 4-methylguaiacol and two to four times as much vanillin at 235oC for both French and American oak. This effect is ascribed to the exposure of a greater surface area of oak to air when smaller fragments are heated. Variable effects were observed for cis- and trans-oak lactone. Variation in chip size, as well as heating time and temperature, is clearly one way of obtaining different aroma profiles from oak products.

Impatiens noli‐tangere L.

<i>Impatiens noli‐tangere</i> L.

Sapwood Area as an Estimator of Leaf Area and Foliar Weight in Cherrybark Oak and Green Ash

Abstract The relationships between foliar weight/leaf area and four stem dimensions (dbh, total stem cross-sectional area, total sapwood area, and current sapwood area at breast height) were investigated in two important bottomland tree species of the southern United States, cherrybark oak (Quercus falcata var. pagodifolia Ell.) and green ash (Fraxinus pennsylvanica Marsh.). In all models tested and for both species, total sapwood area was consistently more highly correlated with foliar weight and leaf area than were the other three measures. However, there was little difference in accuracy among simple linear, multiple, and nonlinear models that used total sapwood area to predict either foliar weight or leaf area. Accuracy was improved slightly through the addition of total height and live crown ratio to the linear model. Foliar weight of both species was best described as a function of total sapwood area and live crown ratio (r2 = 0.97, n = 16 for both species). Leaf area of cherrybark oak was best described as a function of total sapwood area, total height, and live crown ratio (r2 = 0.96, n = 16), whereas leaf area of green ash was best described as a nonlinear function of total sapwood area (r2 = 0.95, n = 16). In contrast with other studies on upland oaks in relatively cool climates, we found that current sapwood area was only a fair estimator of foliar weight and leaf area in cherrybark oak and was a poor estimator in green ash. These results lead to the speculation that more of the sapwood than just the most recent one or two growth rings may be active in water conduction in bottomland species in warm climates. Specific leaf area was highest in the lower crowns of trees of both species and was highest among trees of the lower crown classes. Although based on a limited sample size of four trees per crown class per species, we found that the vertical distribution of foliage within the crown differed among crown classes in both species. Most of the foliage on dominant and codominant trees of both species was concentrated in the upper one-third of the crown, with only a very small proportion of the foliage in the lower one-third of the crown. Intermediate and overtopped cherrybark oaks and intermediate green ash trees had a more even distribution of foliage throughout their crowns, while the foliage of overtopped green ash trees was highly concentrated in the lower one-third of the crown. The leaf area:sapwood area ratio did not differ significantly among crown classes in either species, but averaged 0.67 m2 cm-2 in cherrybark oak and 0.24 m2 cm-2 in green ash. FOR. SCI. 48(1):69–76.

Emergence trapping of mosquitoes (Diptera: Culicidae) in brackish forest habitats in Maroochy Shire, south-east Queensland, Australia, and a management option for Verrallina funerea (Theobald) and Aedes procax (Skuse)

This study details the use of emergence traps with sticky adhesive to capture adult mosquitoes emerging from brackish water pools located in almost impenetrable swamp oak and tea-tree forests in Maroochy Shire, south-eastern Queensland. Twenty emergence traps were set weekly for 12 weeks between March and June 1998, during which time a total of 825 adult mosquitoes were collected. Aedes procax (Skuse) (55%) was the most abundant species, followed by Verrallina funerea (Theobald) (16%) and Culex halifaxii Theobald (9%). Emergence of Ve. funerea was greatest after tidal inundation of pools with brackish water, whereas Ae. procax emerged in greatest numbers following heavy rainfall. As there are significant areas of swamp oak and tea-tree forest in Maroochy Shire and an increasing pressure for urbanisation in adjacent areas, the aerial application of persistent S-methoprene formulations is considered the most appropriate option for control.

The recognition and treatment of depression in older people in primary care.

To examine general practitioners' (GP) awareness of depression in their elderly patients (aged over 65) and to identify characteristics of those patients least likely to be recognized and treated. A cross-sectional study comparing the clinical opinion of the GP with assessment of mental state using a validated interview schedule (the Short Comprehensive Assessment and Referral Evaluation). 510 elderly residents in the Gospel Oak area of Camden in North London registered with 28 GPs at 13 practices. Agreement between GP view and patients interview. Evidence of active management measured by examining GP records for appointments, referrals and prescription of psychotropic mediation. GPs were aware of depression in 36 (51%) of 70 depressed patients. Those least likely to be recognized were men, the married, those with high levels of physical handicap, those suffering from visual impairment and those who were least well educated. Of the 32 patients believed to be depressed, 12 (38%) were prescribed antidepressant medication and/or referred to mental health/social services. Levels of recognition of depression were lower than other recent reports. These findings may reflect the continued debate about the most suitable management of the elderly depressed in primary care and stress the need for further evaluation of appropriate treatment strategies for this group.

Effects of elevated CO2 on stem growth, vessel area and hydraulic conductivity of oak and cherry seedlings

summaryPlants of Quercus robur L. and Prunus avium L. ×P. pseudocerasus Lind, were grown in either ambient (350 vpm) or elevated (700 vpm) CO2. The intention was to examine the effects of elevated CO2 on the morphological and functional development of the stem. The relationships between stem longitudinal transport capacity and development were explored in several ways: stem hydraulic function was related to stem cross‐sectional area, supplied leaf area and total stem vessel lumen area.The mean total vessel number and the total vessel lumen area per stem, for both species, was determined from basal sections of the xylem. In Primus seedlings grown in different CO2 concentrations there was no significant change in the mean vessel size or number of vessels per stem. Quercus seedlings grown at elevated CO2 showed a significant increase in both vessel number and mean vessel size. When total stem vessel area was calculated it had increased twofold for Quercus plants grown at elevated CO2.Measured stem hydraulic conductivity was shown to increase linearly with supplied leaf area, except in Quercus seedlings grown at elevated CO2. Stem hydraulic conductivity for Quercus seedlings grown at elevated CO2 did not change with the increase in supplied leaf area. This absence of an increase in the stem hydraulic conductivity appeared to relate to changes in total stem vessel area. Despite total stem vessel area being greater at elevated CO2 than that at ambient, it similarly did not increase with supplied leaf area.The implications of this change in the relationship between leaf area and stem hydraulic conductivity are discussed with respect to the possible effects the change might have on the plant's water balance. The possible causes and significance of the changes in xylem anatomy are also considered in relation to direct effects caused by CO2 or indirect effects on changes in cambial maturity and tree growth.

Effects of irrigation and fertilization on stem diameter growth in a Mediterranean holm oak forest

The effects of irrigation and fertilization on stem diameter growth are reported for holm oak ( Quercus ilex L.), an evergreen tree that is a common dominant in Mediterranean forests. The experiment was conducted at Prades (northeastern Spain) in a holm oak stand with a high density of stems of resprout origin ( x = 18275 stems ha −1 ), a widespread stand structure in the abandoned coppices that cover extensive tracts of Mediterranean mountains. Mean annual rainfall is 580 mm. Eight treatments were used in each of three blocks, resulting from the factorial combination of: (i) irrigation at rates of about 20 mm week −1 during three consecutive warm seasons; (ii) nitrogen fertilization in a single application of 250 kg N ha −1; (iii) phosphorus fertilization in a single application of 125 kg P ha −1. Stem diameters at 50 cm from the ground were measured before and 3 years after treatment application began. Stem diameter increments in control plots were very low ( x ± SE 0.27 ± 0.07 mm year −1 ), probably as a result of the high stand density and low water availability. Stem diameter growth was positively but loosely correlated with initial stem diameter. Irrigation significantly ( P < 0.01) increased mean stem diameter growth by 66%, but N and P fertilization did not. Surprisingly, there were no significant interactions between irrigation and fertilization, i.e. irrigated and fertilized trees did not grow significantly faster than irrigated-only trees. Effects of irrigation were larger on plots having lower initial basal area of holm oak. Irrigation increased stem diameter growth more in large trees than in smaller ones, thus enhancing the pre-existent inequalities in growth rates. Stem diameter growth in this high density stand is limited by water availability but has not responded to N or P additions during the first 3 years after fertilization.

Stable hydrogen and oxygen isotope studies of rainfall and streamwaters for two contrasting holm oak areas of Catalonia, northeastern Spain

Results are presented of a study of stable hydrogen and oxygen isotopes in rainfall and streamwaters for the Montseny and Prades areas in northeastern Spain: results cover the full year of 1991. The isotopic pattern for rainfall is similar for both areas: there is a wide range in isotopic contents and the results show a strong, near-linear trend, δ 2H = 7.9 × δ 18O + 9.8 ( N = 59; r 2 = 0.952), the ‘local meteoric line’. There is slight curvature to the data which may be related to the sources of water vapour forming the rainfall. Within the streams, the isotopic variability is much less than that of the rainfall although the data lie on, or very near to, the meteoric line. Data for detailed collections during storm events show more scatter than those collected regularly on a fortnightly basis. The event data show a linear feature that conforms to the local meteoric line. These results indicate that: (1) the main supply of water to the stream stormflow comes from water stored in the catchment prior to the event; (2) waters of more than one isotopic composition reside within the catchment and are transferable to the stream during storm events; (3) the main process of water transfer from the catchment back to the atmosphere comes from transpiration by the trees and (possibly) complete evaporation from the near-surface soil horizons and the tree canopy; (4) the isotopic technique cannot be used for quantitative hydrograph separation in this instance — at least two water types can be present within the catchment at any given time.

Impact of chronic gamma irradiation on a Mediterranean forest ecosystem in Cadarache (France)

An area of mixed forest, white oak and evergreen oak in Cadarache (southern France) has been irradiated for 18 years by a 137Cs source. The irradiation effects on the soil system were investigated at five stations along a transect, from 116 mGy h −1 to 0·3 mGy h −1, towards the source and at a control area of non-irradiated forest. The key factor was that there were no ongoing litter inputs to soils in the most irradiated area (100 to 60 mGy h −1) because of the destruction of trees and shrubs. The responses of the edaphic characteristics, biological activities and invertebrate populations of the soils indicated the existence of two main zones, one receiving litter, the second without litter input. In the latter the C and total N fluxes by respiration were significantly reduced. Chronic exposure reduced the carbon biomass and the dehydrogenase activity by around 50% and increased the amount of nitrate in the soil. The structure and composition of animal communities in the soil were changed: microarthropod density was low, ‘other mites’ were dominant. Chronic gamma irradiation had a range of direct and indirect effects. Nevertheless, the degree of disturbance was comparable to those induced by silvicultural practices or by burning. However, the chronic nature of the irradiation maintained the ecosystem under a long-term state of stress.

Oak Influence on Nutrient Availability in Pine Forests of Central Arizona

AbstractExisting evidence suggests that Gambel oak (Quercus gambelii Nutt.) improves soil fertility of the ponderosa pine (Pinus ponderosa Dougl. ex Laws) forest of central Arizona. Greenhouse bioassays were conducted to determine if Gambel oak also influences nutrient availability in the 0‐ to 15‐cm mineral soil layer. Barley (Hordeum vulgare L. cu. Gustoe) and pine seedlings were grown to estimate availability of N, P, K, and S in soils from 15 pine stands with basal area of oak varying from 0 to 62% of the total basal area, but equivalent in all other site factors. Without supplemental nutrients, barley yield from soils with 50% oak was three times greater than from those with no oak. With addition of N, P, K, and S, barley yield increased 370% on soils without oak, but only a 50% yield increase occurred on soils from stands with 50% oak. Regression analysis of barley yields for each nutrient revealed that availabilities of N and S were significantly related to amount of oak present. Availabilities of P and K were not related to oak presence. The bioassay with pine seedlings confirmed that oak positively influenced N supply. This test, however, showed no effect on S supply. Contrasting results for barley and pine tests are attributed to greater sensitivity of barley and high variance in the pine test.

Physiological Responses of Deciduous Tree Root Collar Drenched with Flurprimidol

Root collars of 11 -yr-old pin oak (Quercus palustris), red maple (Acer rubrum), white ash (Fraxinus americana), and black walnut (Juglans nigra) were drenched in June, August, or October 1985 with 2 or 4 g a.i. (W.P.) flurprimidol {a-(1 -methylethyl)-a-[4-(trifluoromethoxy)-phenyl]-5- pyrimidine-methanol} to determine physiological responses. No treatment response occurred the year of treatment but significant terminal and lateral growth inhibition, 43 to 92%, respectively, occurred during the first growing season (1986) following treatment. In general, less growth inhibition resulted from October treatments. However, by the end of the second growing season following application (1987), all treatment combinations inhibited terminal and lateral growth. Leaf area of pin oak and red maple only was reduced (22 to 65%) in 1986 but by 1987 leaf area was reduced 17 to 65% on all species from all treatments. Except for white ash, leaf dry weight was reduced (28 to 64%) by 1987. In general, flurprimidol caused a slight decrease in photosynthetic activity and an increase in chlorophyll concentration but transpiration rates were unchanged. These results indicate that flurprimidol reduces growth without significantly altering energy assimilation or water movement in individual leaves.

A Habitat Suitability Index for White-Tailed Deer in the Piedmont

Abstract A habitat suitability index based on winter foods was designed to evaluate habitat changes affecting white-tailed deer (Odocoileus virginianus) in the Piedmont region of the southeastern United States. Habitat components incorporated in the index were (1) the standing crop of availableherbaceous vegetation and leaves of woody plants remaining green during late autumn and winter, (2) basal area of oak (Quercus spp.) 10" dbh and larger, (3) number of oak species in the stand ≥5% of total basal area, (4) site index of loblolly pine (Pinus taeda) or mixed oak, (5) percentageof agricultural land, and (6) distance from agricultural land to forest or shrub cover. The rationale for inclusion of each component of the index is given, and methods for sampling each habitat component are described. The index should be useful on private small landownerships as well ason larger private and public holdings. South. J. Appl. For. 13(1):12-16

Relative importance of habitat area, isolation and quality for the occurrence of middle spotted woodpecker Dendrocopos medius (L.) in Sweden

In a stepwise regression analysis, oak habitat area and habitat isolation were the most important parameters explaining numbers, density, regularity, and probability of presence in two successive years of middle spotted woodpeckers. No estimate of habitat quality contributed significantly to the equations. A 50% regularity of occurrence during the study period was found in oak areas of 75 ha. It is suggested that, for a small population, habitat fragmentation that gives rise to partially isolated subpopulations will make the population more vulnerable. The large area required by Swedish middle spotted woodpeckers compared with Central European ones, is believed to be a result either of an ‘extinction disequilibrium’ or of poorer habitats in the periphery of the distribution area of the species.

The separation of phosphocreatine from creatine, and pH determination in frog muscle by natural abundance 13C-NMR

Phosphocreatine can be separated from creatine in superfused frog muscle by natural abundance 13C-NMR, based on the difference in resonance frequency of their guanidino carbons. After taking into account the longitudinal relavation times and nuclear Overhauser enhancement factors, the integrated oak areas of the guanidino carbons could be used for determination of the phosphocreatine-to-creatine ratio in the muscle, the pH-dependence of the chemical shift of the C-2 carboon in the histtdine ring of carnosine was used for estimation of the intracellular pH in the intact muscle.

The black spot test for recognizing poison ivy and related species

A black, enamel-like deposit is frequently present on injured areas of poison ivy, poison oak, and poison sumac. This finding can also be produced deliberately as a field test for the toxic nature of the plant. Observing proper precautions, one crushes sap from leaves onto a sheet of white paper. The resulting stain should darken on exposure to the air if it came from a Toxicodendron. This test employs only one quality of these plants, and it is not, therefore, a substitute for other proved means of identification.

Turkey Productivity in Two Vegetative Communities in South Texas

Differences in productivity of the Rio Grande turkey (Meleagris gallopavo intermedis) between mesquite (Prosopsis juliflora) and live oak (Quercus virginiana) vegetative communities on the King Ranch in South Texas were investigated from June 6, 1968, to January 3, 1969. The average brood size in August for the mesquite area, as determined from 1,720 poult observations, was 6.9, while 721 poult observations on the live oak area revealed an average brood size of 4.6 The overall poult: hen ratios at this same ffme were 4.7 and 2.6 while the hens seen without poults xrere 31 and 40 percent respectively. The August productivity, or percent of increase in the population due to reproduction, was 336 percent for the mesquite area and 159 for the live oak. The November, or pre-hunting season productivities were 315 and 129 percent. Poult mortality for the 13-week period, between 2 and 15 weeks of age, was calculated to be 22.9 percent for the mesquite area and 12.1 for the live oak. A helicopter census yielded a calculated density of 56 turkeys per 1,000 acres on the mesquite area and 51 on the live oak. Road counts revealed overestimations of these densities ranging from 95-193 percent. Turkey productivity on the King Ranch in South Texas has fluctuated tremendously from year to year. In years of normal precepitation, production has been good, whereas in dry years there has been almost no production of young turkeys ( W. H. Kiel, Jr., personal communication). There are several possible ecological explanations for this situation, all of which may be related to the limited vegetation during dry years. An assessment was made of the turkey productivity in two vegetative communities, mesquite and live oak. This assessment, in two different environments, explored some of the ecological causes of poor turkey productivity. Field work was carried out from June 8, 1968, to January 3, 1969. Turkey densities on the King Ranch have been reported as being considerably greater in live oak than mesquite (Lehmann 1957 ) . In order that the live oak areas maintain higher turkey densities, there must be, through time, either higher productivity, survival, immigration, or some combination of these factors. 1 Research was supported by King Ranch, Inc., University of Wisconsin, and the Ceasar Kleberg Wildlife Foundation. 166 I gratefully acknowledge W. H. Kiel) Jr.7 biologistv King Range, Inc., and R. A. McCabe of the University of Wisconsin for advice, assistance, and editorial help throughout this project. O. J. Rongstad of the University of Wisconsin, provided suggestions in preparing the manuscript.

A Study of the Mortality Factors Acting upon Cyzenis albicans (Fall.), a Tachinid Parasite of the Winter Moth (Operophtera brumata (L.))

In an earlier paper (Hassell 1968) the behavioural responses of the adult population of Cyzenis albicans (Fall.) at Wytham Woods, Berkshire towards uneven spatial distributions of hosts were considered. To explain the part played by Cyzenis in the natural control of the winter moth population it is the intergeneration relationships that are most important. Only from these can firm conclusions be drawn about the ability of natural enemies to regulate their hosts or prey. An intergeneration relationship is detected when a plot of the yearly mean percentage host mortality (or k-values) caused by the enemy population against the yearly mean host density (or its logarithm) reveals a linear, curvilinear or some form of spiral relationship. Each of these has, of course, very different implications. A curvilinear or rectilinear relationship indicates a superproportional or subproportional relationship depending on whether the slope is positive or negative. Such relationships imply a relatively constant parasite or predator density. A tendency for 'spiralling' to occur when the points are joined serially implies some form of delayed relationship, resulting from changes in the parasite or predator density, which can be caused only by changes in their reproductive rate and/or survival (Hassell 1966). Cyzenis is a specific parasite of the winter moth with a single annual emergence moreor-less synchronized with the availability of host larvae, and so may be expected to play an important part in the control of the winter moth population at Wytham. However, the intergeneration relationship between Cyzenis and the winter moth (Varley & Gradwell 1968) reveals no sign of delayed density-dependency, and the variation in the winter moth mortality due to Cyzenis is clearly insignificant when compared with the variation in generation mortality of the winter moth. The mean density of adult Cyzenis in the area of oak studied at Wytham since 1950 is 0 96/m2 (having varied between 7-2 and 0 1/Im2). In only three of these years has there been more than 700 parasitism of winter moth larvae. In contrast, in Nova Scotia, Canada, where Cyzenis was first introduced in 1954 (Graham 1958), adult parasite densities rapidly increased and in 1960 were causing a mean of 58% parasitism (Embree 1965, 1966). Clearly some unfavourable factor(s) are operating at Wytham and cause Cyzenis to be less effective than in Canada. This paper is concerned with the mortality factors acting upon the Cyzenis population, and a subsequent paper will deal with the construction of a population model describing the fluctuations in parasite density observed in the field.