Site Index Values Research Articles

Relationships between site index modeling of crimean juniper and habitat factors

The aim of this study is to examine the relationships between height growth and some site factors of Crimean juniper in southwestern Anatolia. The data was collected from 130 sample plots selected from 10 districts in western Anatolia. The age and height of the Crimean juniper were measured in each sample plot. Surface soil samples collected from each sample plot were analyzed for pH, organic matter, carbonate content, texture, stoniness, available water capacity, wilting point, and field capacity. All site index values were calculated at a standard age of 100 years old. Spearman and Pearson correlation analyses were used to determine the relationships between plus tree and site factors. According to Spearman's correlation analysis, the site index showed a negative relationship with limestone. According to the results of the Pearson correlation analysis, the numerical variables LATTUD, SLOPE, SURSTON, and HINDEX had a 1% relationship with the site index, and RINDEX had a 5% relationship. Once the binary relationships had been determined, the multivariate relationships were modelled using generalized additive models. The best site index model was obtained using a generalized additive model 1 (R = 0.63), including latitude, longitude, altitude, slope, and stoniness.

Determination of relations between plant species diversity and productivity in Brutian pine stands

This study examines the relationship between Brutian pine productivity and plant species diversity, focusing on its potential as a valuable resource. Data was collected from 101 natural Brutian pine stands in Muğla and Antalya through inventory studies. Age and height values were recorded for three selected Brutian pine trees in each plot, along with plant species diversity using the Braun-Blanquet scale. Site index values were used to assign productivity scores between 1 and 5 for each plot. Diversity values were adjusted to a scale of 1 to 9 according to Westhoff and Maarel (1973) to calculate alpha diversity indices (Shannon and Simpson) using BİÇEB software. Environmental variables such as elevation, slope, radiation index, annual mean temperature, and annual precipitation were also collected for further analysis. The Kolmogorov-Smirnov normality test was first applied to the data matrix. Since it was determined that the normality assumption was not met (p<0.05), the Kruskal-Wallis test, which is a non-parametric method, was used to determine whether there is a significant difference between the diversity values for the site index groups. Results indicated a statistically significant difference (p<0.05) in diversity values among these groups. Then, diversity values and environmental variables were correlated using principal component analysis method (PCA). At the same time, site index groups were also included in the PCA as class data. As a result, it was revealed that Shannon and Simpson diversity values have a negative relationship with elevation and slope and a positive relationship with total annual precipitation.

Factors influencing productivity of pine-dominated stands in South Korea

Stand productivity research has mainly focused on increasing yield and has recently begun to examine changes in carbon storage. The Korean government is interested in finding ways to increase forest carbon capture to meet carbon neutrality requirements because approximately 63% of the land is covered by forests. In addition, 69% of these forests are older than 30 years old and their productivity and aboveground carbon storage rates are expected to decline. The purpose of this study was to examine the effect of quadratic mean diameter (QMD), stand basal area, site index, slope, climate (MAT and MAP), stand age, stand structural diversity, and stand composition on the productivity of aging Korean red pine-dominated stands. Based on the effects of these factors, we explored how to manage pine forests with the focus of increasing their productivity. Random forest regression was used for the analysis, and periodic basal area increment (PBAI) was used as the dependent variable of stand productivity. Our results show that the most influential factor on stand productivity was QMD. PBAI dramatically decreased from approximately 0.8 to 0.53 m2/ha·year as QMD increased up to 18 cm. Since diameter (QMD) increment is closely associated with changes in tree competition; increasing tree competition with increasing QMD and stand basal area may lead to decreases in PBAI owing to decreases in growth rate due to space and resource limitations and increases in mortality. PBAI decreased when basal area increased from 22 to 51.5 m2/ha. PBAI increased for site index values between 8 and 12.5 m and decreased for stand age values up to approximately 31 years. For climate factors, PBAI generally increased with increasing MAP and slightly increased as MAT increased up to approximately 11.2 °C and then decreased at higher MAT. PBAI initially increased with increasing slope values, decreased with values lower than 15°, and remained stable at slope values in the range of 16–34°. Stand structural diversity, which ranged from 1.32 to 1.62, exhibited a similar negative influence on PBAI associated with increasing stand density. With regard to pine composition, pine stands with a large proportion of pine basal area, showed higher productivity due to the simple stand structure resulting in better growth of shade intolerant pine. This study found that stand density increases with the development of pine stands and that density increases had negative influences on stand productivity. Collectively, our results suggest that stand density management is essential for increasing stand productivity and carbon sequestration in the Korean red pine-dominated stands of South Korea.

Development of a site form equation for predicting and mapping site quality. A case study of unmanaged beech forests in the Cantabrian range (NW Spain)

Site form (SF), expressed as the dominant height of a stand at a reference dominant diameter, is used less often than site index (SI) to estimate forest site quality. However, it has the advantage that it is age-independent and can therefore be applied in a wider set of situations in forestry practice. Like SI, elaboration of SF has traditionally required stem analysis or repeated measurements in permanent plots; however, Airborne Laser Scanning (ALS) can nowadays be used to generate site quality practical maps, thereby simplifying the method. The aims of this study were to fit a dynamic equation to stem analysis data in order estimate SF in natural beech forests in NW Spain, as well as to compare the performance of SF for site quality estimation and to analyze the possibility of using ALS data for site quality prediction in these forests. The Algebraic Difference Approach formulation of the Bertalanffy-Richards model provided the best results and defined four curves for dominant heights of 5, 10, 15 and 20 m at a reference dominant diameter of 20 cm. A significant relationship between SF and SI was observed, and we therefore believe that SF is a good approach for site quality estimation. These results can be used directly at inventory plot level for establishing site quality classes without the need to know the stand age, either in terms of SF or translated into SI. On the other hand, ALS data allowed estimation of both dominant height and dominant diameter, although better results were obtained with the former. Applying the SF dynamic model to both data sets enabled prediction of SF at 25x25 m/pixel (and SI using the SI-SF relationship). The overall accuracy of the relationship between the observed SI and that predicted from ALS metrics yielded a coefficient of determination of 0.456 without bias, heteroscedasticity or absence of normality. The results of this unbiased raster model were considered rather good, as predictions were obtained for a pixel size of 25x25 m (0.0625 ha). Prediction of mean SI value for one hectare would thus be necessary to average the values obtained in 16 pixels with an expected error compensation. Use of the raster model based on ALS metrics will enable site quality estimation for current beech stands at high spatial resolution without the need for fieldwork, providing very valuable information for forest managers and researchers.

Model development to estimate site index values for six major tree species in North Korea

Due to considerable deforestation in North Korea, there is a need to plan forest restoration programs based on scientific forest management. In this study, a methodology was developed for estimating the site index values of six major tree species and the forest productivity potential. The site index values of these tree species were derived in South Korea using the Chapman-Richards equation. These values were used with data from the 6th National Forest Inventory, which included 20 types of edaphic, topographic, and climatic factors, and random forest analysis—a widely used machine learning technique for spatial prediction—to develop a new model for estimating the site index values of these species across South Korea. The prediction accuracy of this model was evaluated using the root mean square error. The results show that the prediction accuracy was high, with a root mean square error of ~ 1 m. Moreover, the importance of the variables related to climate and geography was generally high. The proposed site index estimation model for six tree species was applied across North Korea, and its effectiveness tested by comparing the estimated values with those reported in literature from North Korea. The differences between the model outputs and recorded data in the northern alpine regions were presumably due to the lack of data for high-altitude regions in South Korea. This model is based on the determination of the suitability of tree species in restoration efforts. Therefore, it can contribute to the evaluation of forest productivity in North Korea and may help plan efficient forest restoration programs.

Height growth rate of Scots pine in Central Europe increased by 29% between 1900 and 2000 due to changes in site productivity

Increasing atmospheric nitrogen deposition and climate change are considered the main factors accelerating the long-term growth of forests. Quantification of changes in growth rate can be extremely useful in monitoring and assessing the impact of climate change on site productivity.In this study, we carried out a country-wide analysis of long-term (100 years) dynamics and changes in the height growth rate and site index (SI) of Scots pine in Poland. To ensure representativeness we used a large sample of stem analysis trees collected on 312 plots selected using stratified sampling. To control the effect of site fertility and thus avoid the over-representation of older stands on infertile sites, we measured a range of soil properties that, together with environmental indicators characterising climatic conditions and topography, were used in growth trend modelling as explanatory variables.We found that trees planted in successive years have grown faster. The SI calculated for individual trees is linearly dependent on the year of germination and with increasing age of germination, the SI at the base age of 100 years has increased by 8.4 cm per year. Despite the differences in the growth dynamics of pines planted in different germination years, tree growth follows the same growth pattern. The observed continuous changes in site productivity correspond to an increase in the SI by over 29% between 1900 and 2000.A consequence of continuous changes in site conditions and height growth rate is ambiguity in derived SI values. Under changing site conditions, SI values calculated based on stand height and age depend not only on site productivity but also the year of germination. As a consequence, stands growing under identical site conditions show different SIs, which should be acknowledged if the SI is to be used in forest management. Therefore, determining the SI of newly established stands based on the SI of older generations requires the application of an amendment to account for stand age.Continuously improving our understanding of potential climate change impacts on forest ecosystems is essential and provide information to support forest managers seeking to develop effective adaptation measures and determine sustainable forestry production. As such, our results provide valuable support when making long-term decisions and developing effective adaptation strategies in forest management.

Environmental Drivers and Age Trends in Site Productivity for Oak in Southern Poland

Site productivity provides critical information for forest management practices and is a fundamental measure in forestry. It is determined using site index (SI) models, which are developed using two primary groups of methods, namely, phytocentric (plant-based) or geocentric (earth-based). Geocentric methods allow for direct site growth modelling, in which the SI is predicted using multiple environmental indicators. However, changes in non-static site factors—particularly nitrogen deposition and rising CO2 concentration—lead to an increase in site productivity, which may be visible as an age trend in the SI. In this study, we developed a geocentric SI model for oak. For the development of the SI model, we used data from 150 sample plots, representing a wide range of local topographic and site conditions. A generalized additive model was used to model site productivity. We found that the oak SI depended predominantly on physicochemical soil properties—mainly nitrogen, carbon, sand, and clay content. Additionally, the oak SI value was found to be slightly shaped by the topography, especially by altitude above sea level, and topographic position. We also detected a significant relationship between the SI and the age of oak stands, indicating the long-term increasing site productivity for oak, most likely caused by nitrogen deposition and changes in climatic conditions. The developed geocentric site productivity model for oak explained 77.2% of the SI variation.

Anamorphic Site Index Curves for Central Appalachian Red Spruce in West Virginia, USA

Traditional site index curves are frequently produced for shade-intolerant species but are scarce for shade-tolerant species. Red spruce (Picea rubens Sarg.) can be found in three distinct geographic regions (northern, central, and southern) within the Appalachian Mountains. The one commonly used set of red spruce site index curves is over ninety years old. A definite need exists for a modern, regionally applicable set of site index curves. This research sampled 83 plots randomly located in the central Appalachians of West Virginia. Three sets of anamorphic site index curves were created after careful examination of height models built using Chapman-Richards and Meyer functions. One set of curves was constructed with traditional age height pairs. The second utilized a suppression-corrected age and height pair. The third set examined diameter at breast height (DBH) and height pairs. Fit statistics indicated better performance for the suppression-corrected age–height pair site index and the DBH–height pair site index versus the traditional age–height pair models. Site index conversion equations were also investigated for the red spruce age-corrected site index. Linear regression was used to determine significant geographic and climate variables and the utility of including site index values for red maple (Acer rubrum L.) and yellow birch (Betula alleghaniensis Britton) in the model to predict red spruce site index. Significant models were found for varying combinations of species site index, climate, and geographic variables with R2adj in the range of 0.139–0.455. These new site index curves and conversion equations should provide utility for site productivity estimation and growth and yield modeling while aiding in restoration efforts for this important central Appalachian species.

Predicting current and future suitable habitat and productivity for Atlantic populations of maritime pine (Pinus pinaster Aiton) in Spain

By combining inventory data and spatially-continuous environmental information, we were able to develop models for Atlantic populations of maritime pine ( Pinus pinaster Aiton) in Spain in order to predict suitable habitat and site index at a spatial resolution of 250 × 250 m. Currently available, spatially continuous environmental information was used to make reliable predictions about suitable habitat and forest productivity. To develop raster-based distribution and productivity models for Atlantic populations of maritime pine in Spain to predict current and future suitable habitat and productivity. Occurrence data and site index values were obtained from the Third Spanish National Forest Inventory and research plots, respectively. After testing different algorithms, random forest were selected for modelling the relationships between maritime pine occurrence, site index and spatially continuous environmental variables. The overall accuracy of the suitable habitat model was 73%, and climate (mainly thermal properties) and soil physical properties were the most important variables. The site index model explained 60% of the observed variability, and lithological properties were the most important variables. A slight increase in site index (0.46–0.51%) and a large increase in suitable habitat (50–66%) are expected for 2070 under the most pessimistic climate change scenario. The currently available spatial continuous information enables the development of accurate raster data models for predicting suitable habitat and site productivity without the need for fieldwork. Climate change is expected to increase the potentially suitable habitat of Atlantic maritime pine populations in Spain in the coming decades.

Spatial Dependence of the Site Index of Pinus taeda L. Production Forests, in the Southern Central Region of the State of Paraná, Brazil

A spatial analysis of the site index used for the classification of Pinus taeda production forests was performed using dominant height data from 402 continuous inventory plots. The data were examined with simple descriptive statistics and fit with four semivariogram models by the GS + program. The best model was then used to predict the site index in unsampled areas by ordinary kriging in ArcView. All models showed that site index values exhibited spatial dependence, with the degree of spatial dependence ranging from strong to moderate. The spherical model was used for kriging. In this model, the degree of spatial dependence was 29% and the range was 5,330 m, with a residual sum of squares (RSS) of 3.00 and coefficient of determination (r²) of 0.776. Measured and predicted values were compared by cross-validation, which produced a linear regression of observed versus predicted value with a slope coefficient of 1.068, slope standard error of 0.070, and intercept coefficient of -1.45. The site classification map generated by kriging divided the studied forests into five classes. Before kriging, all of the forest stands had one global average value for the site index, but after kriging this was changed to there being two or three values of the site index for many stands. Ordinary kriging proved to be an optimal method for interpolating the site index of unsampled areas to permit their classification, as is the case for young plantations for which inventory samples have not yet been taken.

Age-independent site index mapping with repeated single-tree airborne laser scanning

ABSTRACTA novel method for age-independent site index estimation is demonstrated using repeated single-tree airborne laser scanning (ALS) data. A spruce-dominated study area of 114 km2 in southern Norway was covered by single-tree ALS twice, i.e. in 2008 and 2014. We identified top height trees wall-to-wall, and for each of them we derived based on the two heights and the 6-year period length. We reconstructed past, annual height growth in a field campaign on 31 sample trees, and this showed good correspondence with ALS based heights. We found a considerable increase in site index, i.e. about 5 m in the H40 system, from the old site index values. This increase corresponded to a productivity increase of 62%. This increase appeared to mainly represent a real temporal trend caused by changing growing conditions. In addition, the increase could partly result from underestimation in old site index values. The method has the advantages of not requiring tree-age data, of representing current growing conditions, and as well that it is a cost-effective method with wall-to-wall coverage. In slow-growing forests and short time periods, the method is least reliable due to possible systematic differences in canopy penetration between repeated ALS scans.

THE DYNAMICS OF MENSURATIONAL INDICES AND THEIR SHORT-TERM PREDICTION IN BIRCH-PINE STANDS UNDER A2 TYPE CONDITIONS (FRESH INFERTILE PINE SITE TYPE)

Здійснено моделювання основних лісівничо-таксаційних показників для березово-соснових деревостанів в умовах свіжого соснового бору. Використання деревом площі живлення у повному обсязі є верхнім обмеженням росту у фіксований момент часу. Досягнення максимальних біометричних показників дає змогу дереву найкраще використовувати потенційну родючість ґрунту. З погляду теорії систем, деревостан, що досягає стану динамічної рівноваги, називають оптимальним, який характеризується найвищою продуктивністю. Вплив природних чинників на формування деревостанів зумовлює природний, без антропогенного втручання, розвиток лісостанів, за якого ріст і розвиток дерев забезпечується саморегуляцією. Внаслідок цього формуються динамічно врівноважені,максимально продуктивні біологічні системи. Докладний аналіз процесів росту і розвитку деревостанів у конкретних умовах дає змогу визначати моделі короткотермінового прогнозу окремих показників деревостану для розрахунку інтенсивності та повторюваності доглядових рубань. Встановлено, що збільшення обсягу вирубуваноїдеревини сосни веде до зменшення запасу та істотного збільшення середнього діаметра кращих дерев. Результати прогнозу отримано для інтенсивності доглядових рубань в межах 16–30 % від запасу деревостану на контрольній пробній площі. Отримані динамічні ряди основних таксаційних показників соснових деревостанів у свіжому сосновому борі запропоновано використати як теоретичну основу для подальшого проектування доглядових рубань та формування березово-соснових насаджень із поліпшеною товарною структурою.

Selected properties of organic soils under boreal mire spruce forest in the Romincka Forest, NE Poland

Abstract The paper presents selected properties of the organic soils developed in boreal mire spruce forests (Sphagno girensohnii-Piceetum) in the Romincka Forest (NE Poland). Additionally, the relationship between soil fertility and forest stand productivity was investigated. Data from 12 soil profiles, differing in terms of peatland ecological type (raised bog, transitional bog and fen) was used. The significance of the differences in soil properties among peatland types was assessed with the Kruskal-Wallis test. Soil fertility was described using soil trophic index (SIGo), whereas stand productivity according to site index (SI) value. The properties of the analysed soils varied significantly in terms of peatland type. Soils from fens were more fertile (SIGo 25–31), less acidic (pH > 5.7), with lower total potential acidity (36–40 cmol(+)·kg−1), higher base saturation (77–79%), Ca2+ content (116–136 cmol(+)·kg−1) and base exchange capacity (123–145 cmol(+)·kg−1) than soils from transition or raised bogs. No significant effect of soil fertility on the site index of stands growing on analysed soils was observed (r = 0.385, p = 0.216).

Using the SUBER model for assessing the impact of cork debarking rotation on equivalent annual annuity in Portuguese stands

Aim of study: Use the SUBER model to evaluate the influence of the cork debarking rotation period (CDR) on equivalent annual annuity (EAA) value.Area of study: Nine simulated stands, varying in site index (14.4, 15.6, 17.1) and cork quality characteristics (high, medium, low).Material and methods: EAA values were computed considering CDR periods varying from 9 to 14 years, two contrasting structures of cork prices (high and low cork price scenarios), and three discount rate values (0.5%, 2% and 5%).Main results: For discount rates of 0.5% and 2% the impact of different CDR on the EAA is similar. In stands characterized by high to average site index values or high to medium cork quality characteristics, CDR of 9 and 11 years are associated with similar values of EAA. The variation of the CDR in stands characterized by low site index values and/or low cork quality characteristics did not have a relevant effect on the variation of EAA. For the simulations carried out with a discount rate of 5% the EAA decreases with the increase of CDR, indicating that the minimum legal value of 9 years for CDR should be applied.Research highlights: In stands characterized by high to average site index values or high to medium cork quality characteristics, a delay in the debarking may result in a significant increase of cork thickness and, as a result, of cork price. Detailed knowledge of cork and stand characteristics and updated information on cork prices structure and values are essential for the best usage of management tools such as the SUBER model, which can contribute to the decision-making process concerning the debarking operation.

Caracterización dasométrica e índice de sitio en plantaciones de caoba en Tabasco, México

Se hizo una caracterización dasométrica y se determinó la calidad de sitio, en ocho plantaciones de Swietenia macrophylla King, en parcelas permanentes establecidas en el trópico de México. Las plantaciones estudiadas presentaban edades de 7 a 16 años, densidades de establecimiento de plantación de 156 árb.ha-1 a 1111 árb.ha-1; la supervivencia de 40% a 100%, altura dominante de 4,39 m a 23,45 m, área basal de 2,3 m²ha-1 a 15,7 m²ha-1, volumen de madera con corteza de 14 m³ha-1 a 185 m³ha-1, índice de Reineke de 176 a 505. Con base en la caracterización dasométrica se determinó que las plantaciones con mayor productividad se encuentran en la zona de La Chontalpa. Para determinar la calidad de sitio de estas plantaciones se probaron modelos de Bertalanffy, Chagoya, Logística, Monomolecular, Weibull, Korf y Wescom. El modelo de Korf presentó mejor coeficiente de determinación con alta confiabilidad para realizar la estimación de crecimiento en altura en árboles de la especie estudiada. Con la ecuación obtenida se determinó la evolución de la altura dominante con la edad y el índice de sitio para cada una de las plantaciones. Los índices de sitio para Swietenia macrophylla King en el estado de Tabasco se clasificaron como: baja (11,5 m), media (14,5 m) y alta (17,5 m) con edad base de 10 años.Apartir de los resultados obtenidos, se puede considerar el potencial productivo de esta especie para futuros establecimientos en las zonas con mayores posibilidades

A site index model for lodgepole pine (Pinus contorta Dougl. var. latifolia) in northern Sweden

ABSTRACTA model was developed for predicting site index (SI) values and top height growth of lodgepole pine in northern Sweden. Data on 169 experimental plots from 61 experiments were used for model construction. Six dynamic site equations derived using the generalized algebraic difference approach (GADA) were tested. All of the equations estimate height and SI values on the basis of a known height and total age, and are base-age invariant. Unbiased parameter estimates were obtained by non-linear modelling without accounting for autocorrelation of residuals. The special formulation of the Hossfeld model and the GADA-transformed logistic function produced the most reliable SI curves. The Hossfeld model is recommended as it did not produce extreme outlying estimates for young stands. The developed model is polymorphic with variable asymptotes and can predict SI and dominant height growth for lodgepole pine between 20 and 50 years old.

Determination of Fertility Rating (FR) in the 3-PG Model for Loblolly Pine Plantations in the Southeastern United States Based on Site Index

Soil fertility is an important component of forest ecosystems, yet evaluating soil fertility remains one of the least understood aspects of forest science. We hypothesized that the fertility rating (FR) used in the model 3-PG could be predicted from site index (SI) for loblolly pine in the southeastern US and then developed a method to predict FR from SI to test this hypothesis. Our results indicate that FR values derived from SI when used in 3-PG explain 89% of the variation in loblolly pine yield. The USDA SSURGO dataset contains SI values for loblolly pine for the major soil series in most of the counties in the southeastern US. The potential of using SI from SSURGO data to predict regional productivity of loblolly pine was assessed by comparing SI values from SSURGO with field inventory data in the study sites. When the 3-PG model was used with FR values derived using SI values from SSURGO database to predict loblolly pine productivity across the broader regions, the model provided realistic outputs of loblolly pine productivity. The results of this study show that FR values can be estimated from SI and used in 3-PG to predict loblolly pine productivity in the southeastern US.

Analysis of the energy index as a benchmarking indicator of potential energy savings in the San Antonio, Texas single-family residential sector

Energy consumption baselines are essential in promoting energy efficiency programs in an effort to mitigate the environmental impacts of increasing consumption and increasing home sizes. This study calculates baselines, using site and source energy index (EI), of approximately 348,000 detached single-family homes in San Antonio, Texas to facilitate energy efficiency programs. The data analysis pairs building characteristics of individual houses with their energy consumption, allowing researchers to categorically study houses based on EI, vintage (year built), conditioned space (size), and type of fuel and energy utilized. This study found that the size of single-family detached houses has increased over time, while average site and source energy index values have decreased. The majority of single-family detached houses (45.8 % of total or 159,147 houses) have an energy index of 25–50 kBtu/sf/year (78.8–157.7 kWh/m2/year). The majority of all-electric single-family detached houses have been built since 1980, resulting in better performance than anticipated when compared with houses having access to natural gas. Most homes built after 1990 are distributed in the lower (more efficient) energy index categories, indicating that energy efficiency programs for newer, larger houses should be behavioral or educational in nature while programs for older houses should improve the infrastructure.

Predicting site index from climate and soil variables for cork oak (Quercus suber L.) stands in Portugal

Site productivity, assessed through site index, was modelled using partial least squares regression as a function of soil and climatic variables. Two alternative models were developed: a full model, considering all available explanatory variables, and a reduced model, considering only variables that can be obtained without digging a soil pit. The reduced model was used for mapping the site index distribution in Portugal, on the basis of existing digital cartography available for the whole country. The developed models indicate the importance of water availability and soil water holding capacity for site index value distribution. Site index was related to climate, namely evaporation and frost, and soil characteristics such as lithology, soil texture, soil depth, thickness of the A horizon and soil classification. The variability of the estimated values within the map (9.5–16.8 m with an average value of 13.4 m) reflects the impact of soil characteristics on the site productivity estimation. These variables should be taken into consideration during the establishment of new plantations of cork oak, and management of existing plantations. Results confirm the potential distribution of cork oak in coastal regions. They also suggest the existence of a considerable area, located both North and South of the Tagus river, where site indices values of medium (]13;15]) to high (]15;17]) productivity classes may be expected. The species is then expected to be able to have good productivity along the northern coastal areas of Portugal, where presently it is not a common species but where, according to historical records, it occurred until the middle of the sixteenth century. The present research focused on tree growth. Cork growth and cork quality distribution needs to be further researched through the establishment of long term experimental sites along the distribution area of cork oak, namely in the central and northern coastal areas of the country.

Prognostic significance of Ki-67 index value at the primary breast tumor in recurrent breast cancer.

The Ki-67 index value is a prognostic factor in primary breast cancer and is a proliferation marker that also distinguishes between luminal type A and type B breast cancer. Moreover, a change in Ki-67 index values due to treatment and recurrence is considered to be important in treating breast cancer. In this study, we investigated whether the baseline Ki-67 value in the primary tumor is useful as a prognostic factor following disease recurrence. Immunohistochemical analysis of the Ki-67 index was performed on 4,701 patients with primary breast cancer from 1987 until March, 2013. Among these patients, there were 666 consecutive cases exhibiting recurrence after primary surgery. The fraction of proliferating cells was based on a count of at least 500 tumor cells in the area including the hot spot. The Ki-67 values were divided into 3 groups, namely <20, ≥20 and ≥50%. The investigated items included estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), tumor size, nodal status for the primary tumor, recurrence site (soft tissue, bone and viscera) and disease-free interval (DFI). The Cox's proportional hazard model was used to perform univariate and multivariate analyses of the factors associated with overall survival (OS) following recurrence. The median follow-up period was 65.9 months in the surviving group. The median Ki-67 value at baseline was 20% in all the cases and 27% in the recurrent cases. The Ki-67 values were low (24%) in patients with bone metastasis and significantly higher in patients with liver or brain metastasis (38 and 55%, respectively). Moreover, DFI was found to be inversely correlated with the Ki-67 values. Univariate analysis was performed to identify the prognostic factors for OS after recurrence. The significant factors included tumor size, lymph node status, ER, PgR, DFI, recurrence site and Ki-67 index value. Among these factors, a multivariate analysis identified the Ki-67 index value in the primary tumor as an independent significant factor, particularly in luminal type tumors. The Ki-67 index value in the primary tumor was a significant prognostic factor for OS after disease recurrence. It is, therefore, important to take the Ki-67 index value into consideration for the treatment and follow-up of breast cancer patients.