Differences In Site Quality Research Articles

Currently Available Site Index Equations That Use On-Site Tree Measurements for Naturally Regenerated Longleaf Pine in Its Historical Range

The longleaf pine (Pinus palustris P. Mill.) forest type occupied a much greater area in the United States prior to the arrival of Europeans, estimated to be around 37.2 million hectares. This area has been greatly reduced, and these ecosystems now occupy only about 1.2 to 1.6 million hectares. However, there has been a great interest in the restoration of this forest type mainly due to concerns about the loss of ecosystem services associated with these forests; the improved seedling quality and yield potentials bolster those efforts. Beyond that, existing stands are actively managed through different types of practices, including thinnings, prescribed burns often to manipulate the vegetation of other species, and the various timings of clearcuts. Thus, managers need tools to estimate site quality and ultimately productivity. A commonly used measure of site quality is site index, or the height of some defined dominant portion of the stand at a standardized base or index age. The primary objectives are to summarize the 16 existing equations to estimate site index and dominant height in naturally regenerated longleaf pine stands and to examine and visually compare their predicted behavior across a range of site quality and age conditions. Important considerations when using site index of anamorphism and polymorphism as well as base-age invariance are reviewed. Biologically, polymorphism is often considered advantageous since for many species differences in site quality not only result in different asymptotic dominant heights, but also varying rates in their approach to the asymptote. Of the 16 equations examined, only nine of them were polymorphic in nature, but all equations were base-age invariant. There is not an individual equation that is clearly superior because, for instance, it is either anamorphic in nature, is polymorphic but developed based on anamorphic curves, fit using data obtained from temporary plots, or it is limited geographically. Given these limitations, others can use this publication as a reference to determine which equation they feel is best for their particular situation.

Tree growth potential and its relationship with soil moisture conditions across a heterogeneous boreal forest landscape

Forest growth varies across landscapes due to the intricate relationships between various environmental drivers and forest management. In this study, we analysed the variation of tree growth potential across a landscape scale and its relation to soil moisture. We hypothesised that soil moisture conditions drive landscape-level variation in site quality and that intermediate soil moisture conditions demonstrate the highest potential forest production. We used an age-independent difference model to estimate site quality in terms of maximum achievable tree height by measuring the relative change in Lorey’s mean height for a five year period across 337 plots within a 68 km2 boreal landscape. We achieved wall-to-wall estimates of site quality by extrapolating the modelled relationship using repeated airborne laser scanning data collected in connection to the field surveys. We found a clear decrease in site quality under the highest soil moisture conditions. However, intermediate soil moisture conditions did not demonstrate clear site quality differences; this is most likely a result of the nature of the modelled soil moisture conditions and limitations connected to the site quality estimation. There was considerable unexplained variation in the modelled site quality both on the plot and landscape levels. We successfully demonstrated that there is a significant relationship between soil moisture conditions and site quality despite limitations associated with a short study period in a low productive region and the precision of airborne laser scanning measurements of mean height.

Impacts of climate change on biological rotation of Larix olgensis plantations for timber production and carbon storage in northeast China using the 3-PGmix model

Biological rotation length is a key parameter of even-aged forest management. Future climate change is expected to affect forest growth and thus modify biological rotation age, but knowledge about the effect of climate change on the rotation for both timber production and carbon storage remains limited from process-based growth model. The biological rotation age (BRA) of Larix olgensis plantations in China is technically set for 40 years according to the principle of maximizing timber production, and it is necessary to further examine the BRA with consideration of site quality differences and climate change. On the basis of 164 sample plots from the National Forest Inventory across the Jilin Province, Northeast China, we use the process-based model 3-PGmix to simulate the change of the BRA of Larix olgensis plantations for timber production and carbon storage under climate change. Different climate scenarios are investigated across different site productivity levels. Under the current climate scenario, the BRAs for timber production and carbon storage are approximately 23.8–41.5 years and 25.0–46.4 years, respectively. The BRAs are reduced by 2–9 years under RCP 4.5 and RCP 8.5 climate scenarios. The BRA modification by climate change was site-dependent, and stands with good productivity sites led to shorter BRAs than those with poor productivity sites. The 3-PGmix model effectively simulates the dynamic change of stand volume and biomass for larch plantations. Future climate change with rising temperature, increased precipitation and elevated CO2 concertration is conducive to the growth of stand volume and carbon storage in the order of RCP 8.5 > RCP 4.5 > current. Results can provide scientific implications for adaptive management of Larix olgensis plantations, and shorter biological rotation is suggested for rotation modification under the future climate change in the region.

Symmetry breaking and pivotal individuals during the reunification of ant colonies.

Maintenance of a social group requires the ability to reach consensus when faced with divisive choices. Thus, when migrating colonies of the ant Temnothorax rugatulus split among multiple sites, they can later reunify on the basis of queen location or differences in site quality. In this study, we found that colonies can reunify even without obvious cues to break the symmetry between sites. To learn how they do so, we observed both symmetric reunifications (between identical nests) and asymmetric reunifications (between nests of unequal quality) by colonies of individually marked ants. Both reunification types were accomplished by a tiny minority that carried nestmates from the 'losing' to the 'winning' site. Reunification effort was highly skewed in asymmetric splits, where the majority of the work was done by the first ant to transport, which nearly always came from the winning site. This contrasted with symmetric splits, where the initiator did not play an outsize role and was just as likely to come from the losing site. Symmetric reunifications were also characterized by high transporter attrition, which may help to prevent deadlocks. Tandem runs were abundant in both types and were typically led by transporters as they returned to the losing site to fetch another nestmate. Few tandem followers joined the transport effort, suggesting that tandem runs do not serve to recruit transporters but may have another, as yet unidentified role. Our results underscore the potentially large contribution of highly active individuals to group behaviour, even in decentralized societies such as ant colonies.

Seasonal nutrient retranslocation in reforested Pinus halepensis Mill. stands in Southeast Spain

Retranslocation, resorption and relocation of nutrients are important adaptive mechanisms developed by plants to acquire the amount of the nutrients required for growth. They are usual mechanisms in deciduous and conifer trees that occur in Mediterranean regions where drought periods are usual. Soil factors, environmental characteristics and species factors are key drivers of nutrient retranslocation in conifers but is not well understood how soil fertility or intraspecific competition influences the process. We studied retranslocation in Pinus halepensis Mill. stands showing different site quality (differences in climate and intraspecific competition) occurring in Southeast Spain. We monitored reforested mature Aleppo pine forests in stands with differences in site quality, climate and intraspecific competition. Stands were characterised, the content of nutrients of soil and green samples (twigs and pine needles) were recorded, and seasonal nutrient retranslocation was obtained. Site characteristics were related to growth rate and nutrient content of foliage and soil. We evaluated whether the retranslocation of nutrients from older to younger foliage was related to the current-year growth rate and to the nutritional status of the plant as influenced by intraspecific competition. Foliar macronutrient concentrations and the amount of retranslocated macronutrients were seasonal, with differences related to site quality and tree density. As a general trend, nutrient concentrations increased after drought (autumn) and decreased during the growth period (spring). However, some micronutrients (mainly Na and Fe) decreased during both periods. The retranslocation pattern in Aleppo pine reinforced the hypothesis that pine adaptations to drought- and fire-prone habitats are linked to the resilience of these forest types. We developed scientific knowledge to assist decision making in adaptive forest management; e.g. fertilizer recommendations or reforestation programmes.

Habitat Effect on Allometry of a Xeric Shrub (Artemisia ordosica Krasch) in the Mu Us Desert of Northern China

Allometric models are useful for assessment of aboveground net primary productivity (ANPP) and aboveground biomass (AGB) of forests and shrubs, and are widely implemented in forest inventory and management. Multiple forms of allometric models have been used to estimate vegetation carbon storage for desert shrubland, but their validity for biomass estimation has not been tested at a region scale with different habitats. To verify the validity of habitat-specific models, general models (combining data from all habitats/sites), and previously developed models for biomass prediction, we developed both general models and habitat-specific models for aboveground biomass and ANPP of Artemisia ordosica Krasch, a dominant shrub of the Mu Us Desert. Our results showed that models based on crown area or canopy volume consistently explained large parts of the variations in aboveground biomass and ANPP. Model fitting highlighted that general allometric models were inadequate across different habitats, and habitat-specific models were useful for that specific habitat. Previous models might be inappropriate for other sites because of site quality differences. There was a strong habitat effect on the allometric relationships of A. ordosica. Although our study is a case in point, the results indicate that allometric models for desert shrubs should be used with caution and require robust validation if adopted from other studies or applied to different sites/habitats.

Prediction of Height, Breast Height Diameter and Volume of Eucalyptus microcorys of Sri Lanka

Eucalyptus microcorys is the most valuable Eucalyptus species growing in Sri Lanka. Although the extant of government owned E. microcorys plantations is comparatively small, the attention of private sector planters has been drawn by this species. Therefore the present study was conducted with the objective of predicting the variation of tree height, breast height diameter (dbh) and total stem volume with the tree age. Fourteen E. microcorys plantations were selected for this study from Halgranoya and Nuwara Eliya Forest Ranges of Nuwara Eliya Forest Division. Those plantations were three to 24 years old and the extents varied from 4.5 to 32.5 ha. Circular sample plots of 0.02 ha drawn at random were used for data collection. The number of sample plots varied with the extents of the selected plantations. Total height and dbh of each tree were measured using standard methods. Then each tree stem was visually divided into a few sections and the length, bottom diameter, mid diameter and top diameter of each section were measured. Using these measurements, volume of each section was estimated by Newton‟s formula and the total stem volume was calculated by adding all section volumes. The shape of the final section was assumed to be a cone. When tested, the selected plantations did not indicate significant site quality differences. The tree height and dbh prediction models were constructed assuming them as functions of the age. Tree volume model was built as a function of tree height and dbh. All possible transformations of the candidate variables were tested in constructing those models and the best models were selected based on R2 values and distribution of standard residuals. The selected best three models for height-age, diameter-age and volume-dbh and height relationships had R2 values of 80.1%, 79.5 % and 98.2% respectively. Further, the standard residual distributions of the selected models did not indicate significant biases. Using those models, a two-parameter volume prediction model for E. microcorys was also constructed. Keywords: Eucalyptus microcorys, Stem volume prediction, Two-parameter volume table

Allometric relationships in coppice biomass production for two North American willows (Salix spp.) across three different sites

Biomass yield and component coppice growth traits were assessed for two native North American willow species, Salix discolor (DIS) and Salix eriocephala (ERI), established together in clonally replicated common garden field tests on three sites of differing quality but similar climates. These willows are widely distributed across eastern and central Canada and were selected for use in biomass production plantations. There was no species effect on the average stem length–diameter relationship, but there was a strong site effect. Increased number of stems within a plant decreases average stem diameter but not average stem length. Yield is positively related to site quality and number of stems per plant but also to the interaction between species and number of stems per plant. Allometric relationships between stem basal diameter, stem length, number of stems per plant, and biomass yield (tha−1) clearly reflected site quality differences and could be used in the same way that stem height at a specific age has been used for single stemmed trees to define site quality (site index) in forest timber production. Plant stem length and basal stem diameter measurements on up to 20 stems per plant indicated that measurements based on the average of the three longest stems per plant had the strongest relationship to biomass yield (R2=0.813) and that the average stem diameter of the three largest stems had the strongest relationship to biomass yield (R2=0.781).

Site conditions have an impact on compensation payments for the loss of tree species in mixed forests

Selective browsing of saplings is an unavoidable consequence of high density of wild game and can lead to stand homogenization. To amelioratethe effects of economic risks associated with decrease in species diversification ‐ for example, decreased flexibility in relation to the timber market or increased susceptibility to calamities ‐ compensation payments can be helpful. The risk components in forest economics are now well described. However, even though soil and climate conditions are among the most important factors determining financial gain or loss from forest management, differences due to variations among forest sites are rarely considered in economic analyses. In order to consider the impact of site variation on the financial effects of game browsing, thisstudyfocusedonfinancialresultsofforeststandmodelsconsideredrepresentativeforaveragesiteconditions foreachofthe15growthregionsinBavaria,Germany.UsingtheSilva2growthmodel,theaveragegrowthofspruce (Picea abies (L.) Karst.) and beech (Fagus sylvatica L.) was simulated to consider return‐risk ratios of mixed and homogenized stands ‐ thus to compare target and deviating states. The investigation was divided into two parts: first, as many forest decisions are dependent on financial outcomes, the analysis of the financial impact of varying site conditions began by calculating the annuities. Second, it was important to see what influence site conditions might have on compensation payments. The results showed that fluctuations in spruce growth rates among 15 growth regions of Bavaria were much higher than those for beech. Because of the loss of beech, when calculating necessary riskcompensation levels, the results were largelydependent on the variations in beech growth and the financial risk level of spruce ‐ both due to differences in site quality.

Stand dynamics, spatial pattern and site quality in Austrocedrus chilensis forests in Patagonia, Argentina

Aim of study: The objective of this study was to analyze the stand structure and spatial pattern of two A. chilensis stands with contrasting soil conditions and different site qualities in order to explore if these differences lead to patterns similar to the ones observed under different precipitation conditions.Area of study: The study was carried out in two stands located near the city of El Bolsón (41° 56’S - 71° 33’ W), Rio Negro, Argentina.Material and Methods: We evaluated age difference between canopy strata (upper and lower) in two stands with different site qualities by means of a Mann-Whitney test. Dead individuals by diameter class were compared by means of a chi square test. Spatial distribution pattern was analyzed using the pair-correlation function and the mark-correlation function.Main results: Both sites exhibited a random spatial distribution of A. chilensis but different processes seem to underlie the patterns. In the low-quality site facilitation and continuous establishment led to a transient clumped spatial pattern. Mortality mediated by competition occurred mainly on small trees resulting in the current random pattern. On the other hand, spatial pattern in the high-quality site does not reflect a facilitation mediated recruitment. The upper strata established synchronously and subsequent regeneration was episodic.Research highlights: The results show that the differences in site quality may lead to different establishment spatial patterns, showing the importance of facilitation processes in sites with drier soil conditions and lower quality, although results may be site specific, due to the lack of replications.Keywords: Spatial analysis; regeneration; mortality; competition; facilitation.Abbreviations used: LQ: low-quality site; HQ: high-quality site.

Economic and employment implications of a carbon market for integrated farm forestry and biodiverse environmental plantings

Many studies have predicted, at a national scale, the economic viability of new forestry plantings to contribute to mitigation of greenhouse gas emissions in Australia's cleared agricultural lands. Such predictions are highly uncertain given: (i) differences in site quality, management regimes and planting geometries (belt versus block configurations) result in rates of sequestration that are highly variable at regional scales and (ii) uncertainties in carbon accounting methods in future carbon markets. Here we examined the economics of three case studies (two of farm forestry and one of biodiverse environmental plantings) to address these issues. There was significant variation in economic viability both between and within case studies (average coefficient of variation of 39%) as a result of differences in site quality, management regime and planting geometries. We conclude that if carbon offset investment targets marginal land (i.e. areas of farms of lowest productivity), carbon prices required for economic viability are <$18t CO2-e, even at a relatively high discount rate of 8%. Although regional employment generated per hectare tends to be less than many existing agricultural enterprises, any jobs generated from use of this low productivity land for carbon forestry would be additional. Economic viability was generally greatest for 3−4 row belt farm forestry plantings because of increased growth, particularly in areas of relatively high rainfall. Supplementary payments may therefore be needed to make biodiverse environmental plantings competitive in areas of lower rainfall and thus less profitability.

Small-scale demographic structure suggests preemptive behavior in a flocking shorebird

Under the ideal-free distribution, omniscient individuals with similar habitat requirements that are free to move should be distributed such that no individual can improve fitness by changing sites; deviations would indicate trade-offs and constraints on ranging behavior. We studied site occupancy and annual survival in red knots Calidris c. canutus at their main wintering area Banc d’Arguin, Mauritania. We collected mark-resighting data at 2 high-tide roosts (A and B) that were only 3 km apart and within sight. Birds were faithful to their roosts and foraged in nearby intertidal areas, with no overlap between birds from A and B. Shellfish-rich seagrass beds were of greater abundance for birds roosting at A than at B. During 8 winters, we found different sex ratios (48% and 58% males at A and B, respectively) and different proportion of juveniles (22% and 45%) at the 2 roosts. Adult annual survival was higher at A (0.83±0.01 standard error [SE]) than at B (0.81±0.03). Though rare, between winter season movements were 3 times more frequent from B to A than vice versa, indicating that knots can assess the differences in site quality: birds behaved as if they were “ideal”. As larger females and older birds occurred more at A, differences in competitive ability might maintain the site occupancy pattern. As females return from the high Arctic breeding grounds first, and adults return before juveniles, priority of occupancy may also play a role. Such an advantage of arriving earlier would represent a seasonal carryover effect.

Evaluating variations of physiology-based hyperspectral features along a soil water gradient in a Eucalyptus grandis plantation

Remote sensing is viewed as a cost-effective alternative to intensive field surveys in assessing site factors that affect growth of Eucalyptus grandis over broad areas. The objective of this study was to assess the utility of hyperspectral remote sensing to discriminate between site qualities in E. grandis plantation in KwaZulu-Natal, South Africa. The relationships between physiology-based hyperspectral indicators and site quality, as defined by total available water (TAW), were assessed for E. grandis plantations through one-way analysis of variance (ANOVA). Canopy reflectance spectra for 68 trees (25 good, 25 medium and 18 poor sites) were collected on clear-sky days using an Analytical Spectral Device (ASD) spectroradiometer (350–2500 nm) from a raised platform. Foliar macronutrient concentrations for N, P, K, S, Ca, Mg and Na and their corresponding spectral features were also evaluated. The spectral signals for leaf water – normalized difference water index (NDWI), water band index (WBI) and moisture stress index (MSI) – exhibited significant differences (p < 0.05) between sites. The magnitudes of these indices showed distinct gradients from the poor to the good sites. Similar results were observed for chlorophyll indices. These results show that differences in site quality based on TAW could be detected via imaging spectroscopy of canopy water or chlorophyll content. Among the macronutrients, only K and Ca exhibited significant differences between sites. However, a Tukey post-hoc test showed differences between the good and medium or medium and poor sites, a trend not consistent with the TAW gradient. The study also revealed the capability of continuum-removed spectral features to provide information on the physiological state of vegetation. The normalized band depth index (NBDI), derived from continuum-removed spectra in the region of the red-edge, showed the highest potential to differentiate between sites in this study. The study thus demonstrated the capability of hyperspectral remote sensing of vegetation canopies in identifying the site factors that affect growth of E. grandis in KwaZulu Natal, South Africa.

Age effects on carbon fluxes in temperate pine forests

This study evaluates age-related patterns of ecosystem carbon (C) fluxes in a chronosequence (5-, 18-, 33-, and 68-year old in 2007) of planted pine ( Pinus strobus L.) forests in southern Ontario, Canada, from 2003 to 2007. Carbon fluxes determined with the eddy covariance technique were normalized by differences in site index (SI; a measure of site quality based on a species-specific relationship between the height of the dominant trees and base age), to identify the effect of stand age on gross ecosystem productivity (GEP), ecosystem respiration (RE), and net ecosystem productivity (NEP). Observed GEP, RE, and NEP were highest in the 18-year-old stand, which differed from the two older stands by having a higher SI due to sustained availability of soil water in deeper soil layers (at ∼1 m depth). Typical age-related patterns in C fluxes were observed only when normalized for differences in SI. During periods without climatic constraints, SI-normalized GEP and RE increased with stand age, whereas SI-normalized NEP peaked at the 33-year-old site. In contrast, during periods with climatic constraints (e.g. drought, reduced radiation), monthly GEP and NEP at the 18-year-old site were higher compared to the 33-year-old site because deep soil water availability may have allowed this stand to maintain high productivity during these periods. Our analysis shows that differences in site quality may affect the interpretation of age-related C flux dynamics in chronosequence and synthesis studies. We therefore suggest that SI-normalization may offer a simple and efficient way to identify age-dependent processes in C fluxes in forest chronosequence studies, which may lead to improved large-scale estimates of C exchanges in forest ecosystems.

Nutrient return via litterfall in two contrasting Pinus sylvestris forests in the Pyrenees under different thinning intensities

Thinning influence on litterfall chemical composition (N, P, K, Ca and Mg) was studied for 30 months in two contrasting Pinus sylvestris L. stands in the western Pyrenees mountain range (Northern Spain): Aspurz (625 m.a.s.l, high productivity, Mediterranean climate) and Garde (1335 m.a.s.l, low productivity, continental climate). Two different thinning intensities were carried out by removing 20% and 30% of pre-thinning basal area. In accordance with site quality differences between sites N, K, Ca and Mg total soil returns via litterfall were significantly higher in Aspurz than in Garde. However, P, K, Ca and Mg concentrations were higher in Garde and N higher in Aspurz. Changes in nutrient concentrations over time varied depending on litterfall fractions, showing a variety of patterns; seasonal (N, P, K) or erratic patterns (Ca, Mg) in Aspurz, and seasonal (N, P), biannual (Ca, Mg) or erratic (K) patterns in Garde. In addition to these patterns, differences in nutrient concentrations between years were found in needle litter in Aspurz but not in Garde. Nitrogen returns to forest floor via litterfall were more constant in Aspurz but followed a pulse dynamics in Garde, with the opposite for P, due to important returns from the miscellaneous fraction in the Mediterranean site. Thinning reduced nutrient returns via litterfall in both sites, but significant differences were found only in summer. These results suggest that Aspurz (Mediterranean stand) is more sensitive in the short-term to human intervention than Garde (continental stand) and therefore site-specific forest management plans should be used within more general region-wide plans in order to ensure sustainability of forests.

Modelling mean above and below ground litter production based on yield tables

Estimates of litter production are a prerequisite for modeling soil carbon stocks and its changes at regional to national scale. However, the required data on biomass removal is often available only for the recent past. In this study we used yield tables as a source of probable past forest management to drive a single tree based stand growth model. Next, simulated growth and timber volume was converted to tree compartment carbon stocks and biomass turnover. The study explicitly accounted for differences in site quality between stands. In addition we performed a Monte Carlo uncertainty and sensitivity analysis. We exemplify the approach by calculating long-term means of past litter production for 10 species by using yield tables that have been applied in Central Germany during the last century. We found that litter production resulting from harvest residues was almost as large as the one from biomass turnover. Differences in site quality caused large differences in litter production. At a given site quality, the uncertainty in soil carbon inputs were 14%, 17%, and 25% for beech, spruce, and pine stands, respectively. The sensitivity analysis showed that the most influential parameters were associated with foliage biomass and turnover. We conclude that rates of mean past litter production and their uncertainties can reliably be modeled on the basis of yield tables if the model accounts for 1) full rotation length including thinning and final harvest, 2) differences in site quality, and 3) environmental dependency of foliage biomass and foliage turnover.

Spatial dispersion of trees in an old-growth temperate hardwood forest over 60 years of succession

An analysis of spatial dispersion was conducted for individual tree species in the old-growth forest at the Davis-Purdue Research Forest in Indiana. This 20.6 ha stand has been left largely undisturbed by exogenous factors since its acquisition by Purdue in 1917. It is the only long-term study plot of its size for a temperate hardwood forest with x– y coordinates (rectangular plot) for all species above 10 cm diameter. Full censuses have been conducted spanning 60 years (1926, 1976 and 1986). Ripley’s L( t) function revealed that most species are characterized by some form of aggregation, agreeing with a prior evaluation from 1981. Heterogeneity of spatial structure was evident between two large plots, indicating that differences in site quality and history had influenced spatial structure. Shade-intolerant species were numerically dominant and spatially aggregated in 1926 but have declined over the 60-year interval and become more random in spatial dispersion. Shade-tolerant species have increased in number and become more aggregated over time, or they exhibit little change in spatial structure. Examples of the latter include Acer saccharum and Ulmus americana, species that experienced explosive population growth. These contrasting patterns are masked by stand-level patterns that show a trend toward uniformity over the same time frame. These data reveal that changes in dispersion accompany the demographic failure experienced by numerous tree species in Central Hardwood old-growth stands, and these changes may feed back into a negative population cycle and further impede regeneration. The simultaneous manipulation of dispersion and density should be considered as a tool for influencing forest succession and promoting regeneration of desired tree species.

Intersite differences in population demography of Mountain Pygmy-possums Burramys parvus Broom (1986–1998) : implications for metapopulation conservation and ski resorts in Koskiuszko National Park, Australia

Small, local populations of the endangered Mountain Pygmy-possum Burramys parvus occur on the Koskiuszko Plateau, in south-eastern Australia, including within ski resort lease areas. Between 1986 and 1998 four populations, two within and two outside ski areas, were studied to assess their dynamics and to determine if ski resort management was likely to impact on the conservation of the species. One of the resorts, at Mount Blue Cow, was constructed as the study commenced. Analysis of the 11–12 year data sets showed strong site differences in sex ratios, annual and winter survival rates, site persistence, recruitment and spring weights. Regional trends, attributed to exogenous climatic factors, were evident but population fluctuations were generally uncorrelated and strong site by year interactions occurred for most demographic parameters. Despite this, strong density dependence on all sites in recruitment and to a lesser extent annual survival suggest B. parvus is habitat limited and that social factors drive demographics in these populations. There was no evidence that the ski resort at Mount Blue Cow had any significant impacts above natural yearly variation in demographics in the first 11 years of its operation. However, the highest quality sites, in terms of population size and stability, were those within the two ski resort lease areas. Further, the asynchronous population dynamics, a small amount of migration between habitat patches, differences in site quality and heterogeneity in site structure and aspect, which may contribute to population persistence, indicates that a metapopulation approach to conservation of B. parvus on the Kosciuszko plateau is warranted. This has important implications for long-term conservation of B. parvus in the ski resort areas. These sites will require careful monitoring and management to ensure the continued viability of the resident and surrounding B. parvus populations.

Influences of Forest Type, Stand Age, and Weather on Deer Weights and Antler Size in the Southern Appalachians

Abstract We analyzed correlations of forest type, age structure, and site index data with weights and antler characteristics of yearling white-tailed deer (Odocoileus virginianus) bucks from specific localities in the Chattahoochee, Cherokee, Nantahala, and Pisgah national forests in Georgia, Tennessee, and North Carolina. Areas in the northern part of the study region produced larger deer with larger antlers than those in the southern portion of the region. These northern areas differed from those to the south in having more diverse ownership and land use and in origins of deer stock. Weights and antler characteristics were significantly correlated (P &lt; 0.05) with percent area in the cove hardwood type, but otherwise were poorly correlated with forest stand type and site index. Percent area in young (0-8 yr old) cove hardwood and in mid-successional (9-20 and 21-40) cove hardwood, pine (Pinus spp.), and upland oak (Quercus spp.) were significantly correlated (P &lt; 0.05) with deer variables, particularly in years following a poor mast crop. Much of the quantifiable habitat influences on deer in the Southern Appalachians probably is masked by low deer densities and the small site quality differences among areas examined. Because much of the forest consists of mature mast-producing oaks and abundant forage is produced in both mature and younger aged stands, deer numbers seem to be below any threshold of quantifiable effects due to forest stand age structure. South. J. Appl. For. 21(1):11-18.

Site classification in a mixed hardwood forest (Hallerbos, Belgium) with a homogeneous ground vegetation dominated by Hyacinthoides non-scripta (L.) Chouard ex. Rothm.

The forest of Halle (560 ha), situated 20 km south of Brussels is covered by a beech (Fagus sylvatica) forest, locally mixed with secundary species (Tilia, Fraxinus, Acer, Quercus,... ). In almost all stands, herbal vegetation is dominated by bluebell (Hyacinthoides non-scripta). The research intended to classify 36 plots of different tree species composition according to their site quality. Three classification methods were compared: the first one based on the indicator value of the understorey vegetation, a second one on the humus morphology and a last one on some quantitative soil characteristics. According to the plant sociological site classification, the plots have the same site quality. However, humus forms differ apparently and significant differences were found in pH value and base cation saturation of the soil, abundance and biomass of earthworms and biomass of the ectorganic horizon. Tree species proved to be the main cause of these differences. The results illustrate that the herbal vegetation is not always a reliable indicator of site quality. In the case of a homogeneous vegetation dominated by one or more indifferent species, classification on humus morphology or soil analysis are more appropriate. In the forest of Halle, the tree species is probably the main cause of the observed differences in site quality.