Modelling primary branch growth based on a multilevel nonlinear mixed‑effects model: a Pinus koraiensis plantation case study in north‑east China

On the basis of a multilevel nonlinear mixed?effects model approach, branch diameter and length growth models were developed for a Pinus koraiensis plantation in north?east China. The models developed were able to better capture the residual variation successfully by partitioning the residual variance into plot?, tree? and branch? level variations via random parameter modeling at the three levels. In addition to random effects, various time series correlation structures were evaluated to account for residual autocorrelation, and the AR(1) and ARMA(1,1) structures were selected for the branch diameter and length growth models, respectively. Model validation results using an independent data set confirmed that multilevel mixed models with an appropriate correlation structure produced more accurate and precise branch?specified diameter and length predictions. Overall, the models were suitable in describing the trends and inherent variability of crown profile and good enough to be included in growth simulation systems for Pinus koraiensis plantations.     

Carbon stocks in a 50‑year‑old Eucalyptus camaldulensis stand in Sicily,Italy

Eucalyptus stands in semi?arid areas may contribute to enhance carbon (C) stocks in both biomass and soil. However, the limited information available is mainly focused on short?rotation plantations. In this study, the above? and below?ground C pools in five 50?year?old Eucalyptus camaldulensis Dehnh. stands planted on Miocenic evaporitic deposits in Sicily, Italy, with a xeric and thermic pedoclimate, were measured. Above?ground biomass was determined by partitioning and weighing branches, stem and leaves. Below?ground C pools included the determination of litter, root biomass, and soil organic and inorganic C. In terms of the above?ground biomass, the E. camaldulensis stand accumulated on average 116?Mg ha?1 corresponding to 55?Mg C ha?1. Below?ground biomass consisted mainly of larger roots, followed by fine and medium roots (33?Mg ha?1 corresponding to 14?Mg C ha?1). Litter accumulation on the soil surface accounted for 13?Mg ha?1 corresponding to 5?Mg C ha?1. The amount of C stored in soil was 554?Mg C ha?1, of which 75% was in organic form. Although E. camaldulensis is planted extensively throughout the Southern Hemisphere and tropics where it is managed over short rotations (c. 2–4 years), the results obtained from this study make this species important in terms of future afforestation planning for longer rotations due to its potential to sequester C, particularly in the below?ground components.     

Fire Occurrence Environments in Pinus pumila Forests

In recent years, many serious forest fires occurred in precious Pinus pumila forests in Daxing'anling Mountains of Heilongjiang Province and Inner Mongolia. But up to now, there is still a lack of proper understanding of fire occurrence environments in P. pumila forests. In present paper, we investigated and studied the fire occurrence environments. The results showed that fires in P. pumila forests had their own special fire environments. Abundant fuel, drought weather, dry thunder and high altitude terrai...     

Are neighboring trees in tune? Wood formation in Pinus pinaster

Neighboring trees growing under identical environmental conditions can exhibit different dynamics and periods of growth. Despite the recent advances in cambial biology, the exogenous and endogenous factors generating asynchronous xylem growths still remain undetermined. This study investigated timings and duration of xylem formation in maritime pine (Pinus pinaster Ait.) from an even-aged plantation in Portugal growing under Mediterranean climate. Cambial phenology and stem diameter were monitored weekly, from March to December 2010, on two classes of trees divided according to the tree ring widths of the last 15 years, but similar age and size: fast- and slow-growing trees. We tested the hypothesis that differences in tree ring widths result from cell production which in turn affects timings of xylogenesis and that the bimodal growth pattern, typical of the Mediterranean, originates from a double reactivation of the cambium: in spring and autumn. Cambial activity started earlier and ended later in fast-growing trees, confirming that cell production is a key factor determining the duration of xylogenesis. Intra-annual variations in stem diameter recorded by band dendrometers revealed two peaks of increment occurring in spring and late summer. However, the number of cambial cells did not increase in late summer, which suggested that the second peak of increment was caused by stem rehydration, rather than by a reactivation of cell division. These results demonstrated that the variability in the timings of xylem phenology observed among trees of the same age and size and growing under similar environmental conditions was closely related to cell production and not to age or size per se.     

Changes in nutrient concentrations and nutrient release in decomposing needle litter in monocultural systems of Pinus contorta and Pinus sylvestris—a comparison and synthesis

Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta) needle litters were compared in terms of nutrient composition and its change during decomposition. Initial nutrient composition differed between the species, with lodgepole pine needle litter having significantly higher concentrations of P, Mg and Mn. However, no difference was found for concentrations of N, Ca or K. Increases in concentrations of N, P and K during decomposition were significant in both litter types. For Ca the pattern of concentration changes followed a quadratic function as decomposition proceeded. Concentrations of Mg and Mn decreased in lodgepole pine needle litter. In Scots pine litter there was also an initial decrease, but it was followed by an increase in most incubations. For both Mg and Mn, changes in concentrations during decomposition differed significantly between species. In the late decomposition stages, concentrations of Mg and Mn became similar in both litter types. Nutrient concentrations generated by the models were compared with those of the humus (F and H) layer in the stands. The model was quite accurate in predicting concentrations of N and P for both species and the concentration of Mg for lodgepole pine. By contrast, it was not accurate in predicting concentrations of Ca and Mn. Nutrient release was estimated for the two species using both measured litterfall data and long‐term estimates, and regression models were used to predict concentration changes. Rates of release of P, Mg and Mn in the lodgepole pine stands were found to be about twice as high compared with those in Scots pine. Calcium was also released to a greater extent although the difference was not significant.     

Tree and stand structure of the non-native Pinus contorta in relation to native Pinus sylvestris and Picea abies in young managed forests in boreal Sweden

Managed forest stands are typically younger and structurally less diverse than natural forests. Introduction of non-native tree species might increase the structural changes to managed forest stands, but detailed analyses of tree- and stand-structures of native and non-native managed forests are often lacking. Improved knowledge of non-native forest structure could help clarify their multiple values (e.g. habitat for native biodiversity, bioenergy opportunities). We studied the structural differences between the introduced, non-native Pinus contorta and the native Pinus sylvestris and Picea abies over young forest stand ages (13–34 years old) in managed forests in northern Sweden. We found that P. contorta stands had greater mean basal areas, tree heights, diameters at breast height, and surface area of living branches than the two native species in young stands. The surface area of dead attached branches was also greater in P. contorta than P. abies. Although this indicates greater habitat availability for branch-living organisms, it also contributes to the overall more shaded conditions in stands of P. contorta. Only one older 87 years old P. contorta stand was available, and future studies will tell how structural differences between P. contorta and native tree species develop over the full forestry cycle.     

Growth and dynamic modulus of elasticity of Pinus patula × Pinus tecunumanii hybrids in Mpumalanga,South Africa

Field establishment of South Africa’s most important commercial pine species, Pinus patula, is severely hampered by the pitch canker fungus, Fusarium circinatum. Importantly, hybrids between P. patula and other pine species tolerant to the pitch canker fungus, such as P. tecunumanii and P. oocarpa, have been identified as an alternative planting stock. In this study, variation in tree volume and dynamic modulus of elasticity (MOE_dym) of the P. patula × P. tecunumanii (low- and high-elevation [LE and HE] ecotypes) hybrid was compared with the P. elliottii × P. caribaea hybrid, and the pure species P. tecunumanii (LE) and P. patula. The MOE_dym was assessed using the Fakkop TreeSonic microsecond instrument across three sites. The results of the study showed that P. patula × P. tecunumanii LE performed significantly better than P. patula × P. tecunumanii HE for volume and MOE_dym, which in turn was significantly better than P. patula. The MOE_dym and tree growth decreased with an increase in elevation. There was significant taxon × site interaction for volume and MOE_dym. The results of these trials suggested that P. patula × P. tecunumanii LE is a suitable alternative to P. patula in the Sabie region of Mpumalanga in South Africa on frost-free sites, in terms of the traits that were assessed.     

Performance of Pinus elliottii, Pinus caribaea, their F1, F2 and backcross hybrids and Pinus taeda to 10 years in the Mesopotamia region, Argentina

Performances of Pinus taxa were studied to 10 years of age in two trials in each of Misiones and Entre Ríos provinces across the Mesopotamia region of Argentina. Taxa comprised 22 populations from sources in Argentina, Australia, Brazil and Zimbabwe including Pinus elliottii var. elliottii (Pee), Pinus caribaea var. hondurensis (Pch), their four, inter-specific hybrids (F₁, F₂ and backcrosses from F₁ to Pch and to Pee—all as broadly based bulks); other Pee and Pinus taeda (Pt) comprised narrower or unspecified bulks. Variable numbers of taxa were missing at each site. Mean survival across sites at age 10 years ranged 53.2–91.3% averaging 74.2%. Analysis of variance of plot means indicated population effect was statistically significant (p < 0.05) for all or most growth and quality traits at all sites. However, significant differences from the nominated check seedlot at the Entre Ríos sites (Pee, Australia) were extremely rare, while quite common at the northern, Misiones sites (check seedlot a Pt population). In the Misiones trials, F₁, F₂ and both backcross hybrids showed better stem straightness than Pee and Pt from Argentina, generally with statistically significant differences (p < 0.05). Pt showed lowest forking scores (desirable). Taxon × environment interaction was statistically significant (p < 0.01) for growth traits only (p > 0.05). However, this interaction contributed an average of only 34.1% of the taxon variance suggesting a lack of practical importance. Taxa most suitable for deployment in the Mesopotamia region, Argentina are suggested.     

Sawn-timber and kraft pulp properties of Pinus elliottii × Pinus caribaea var. hondurensis and Pinus patula × Pinus tecunumanii hybrids and their parental species

A study was undertaken to evaluate the quality of the timber produced by Pinus elliottii × Pinus caribaea var. hondurensis (PECH) and the Pinus patula × Pinus tecunumanii low elevation (PPTL) and high elevation (PPTH) hybrids and their parent species for both kraft pulp and sawn-timber production. Trees were taken from unthinned tree improvement trials managed for pulpwood, ranging in age between 15 and 19 years. All sawn boards produced by study trees met the minimum wood density requirement for S5-grade structural timber (360 kg m^?3), but approximately 17% of the boards failed to meet the other requirements for the grade, largely due to knot-related defects. Results of dynamic modulus of elasticity assessments performed on all of the boards suggested that a large percentage of boards would not meet the specified average stiffness (7 800 MPa). This was confirmed by the results of static bending tests performed on a subsample of boards. All boards tested for all species and hybrids met the required fifth percentile bending strength value for grade S7 (15.8 MPa) according to SANS 6122 (2008) specifications. The kraft pulping results indicated that the samples taken from the upper part of the stem yielded slightly better results on average than the samples representing the whole tree with respect to uniformity in the kappa vs charge and temperature, and yield vs kappa traits, with slight improvement of pulp yield (52% vs 50%) and some strength properties compared with whole tree pulping. Samples from the upper part of the stem had a close delignification rate in the 60–80 kappa range. The delignification rate for PPTL in the 60–80 kappa range was slower and the yield was slightly lower than P. patula (53.17% vs 52.72%) despite a higher kappa number. The pulp strengths short-span compressive test, breaking length and tearing strength of PECH were similar to those of P. elliottii, which were in turn generally lower than those of P. patula. The pulp strengths of PPTL and PPTH were similar to those of P. patula, whereas P. caribaea strengths were intermediate between those of P. patula and P. elliottii. With the exception of a slightly lower pulp yield, PPTL emerged as the best all-round hybrid for both pulp and sawn-timber properties.     

Photosynthetic induction responses of Pinus koraiensis seedlings grown in different light environments

The time processes of photosynthetic induction responses to various irradiances in Korean pine (Pinus koraiensis) seedlings grown in open-light environments and in understory of forest were studied in an area near the Research Station of Changbai Mountain Forest Ecosystems, Jilin Province, China from July 15 to August 5, 1997. The results showed that at 200 μmol·m⁻²·s⁻¹ photosynthetic photon flux density (PPFD) and 500 μmol·m⁻²·s⁻¹ PPFD, the induction time for the photosynthetic rates of understory-grown seedlings to reach 50% and 90% steady-state net photosynthetic rates was longer than that of the open-grown seedlings. The induction responses of open-growth seedlings at 500 μmol·m⁻²·s⁻¹ PPFD were slower than those at 200 μmol·m⁻²·s⁻¹ PPFD, but it was the very reverse for understory-growth seedlings, which indicates that the photosynthetic induction times of Korean pine seedlings grown in the understory depended on the sunfleck intensity. Biograph: ZHOU Yong-bin (1970-), female, associate professor of Shenyang Agricultural University, Shenyang 110161, P.R. China. Responsible editor: Song Funan     

Genetic Differentiation of Pinus koraiensis under Different Altitude Conditions in Changbai Mountain

The genetic differentiation of Korean pine (Pinus koraiensis) in different altitudes in Changbai Mountain was analyzed by ISSR technique, and it was found that the level of genetic diversity of Korean pine reduces along with altitude increasing in Changbai Mountain. The variation of Korean pine is mainly from intra-population and there is a positive relativity between genetic distance and vertical geographic distance of Korean pine in different altitudes. The genedc coherence shows that altitude has less insulation to Korean pine. Therefore, it is deduced that the terrain formation of vertical distribution of Korean pine is a result of diffusion from lower altitude to higher altitude in the course of enlarging its adaptability.     

Struktur und Langzeitentwicklung von subalpinen Pinus montana Miller und Pinus cembra L. W?ldern in den zentraleurop?ischen Alpen

Zusammenfassung:  Die traditionelle land- und forstwirtschaftliche Nutzung dürfte im Alpenraum in der näheren Zukunft wirtschaftlich bedingt immer häufiger aufgegeben werden. Dieser Trend wird mit großer Wahrscheinlichkeit die Dynamik von Gebirgsökosystemen und damit das Landschaftsbild stark beeinflussen. Aus diesem Grund stieg in den letzten Jahrzehnten das Interesse, die Sukzession auf nicht mehr bewirtschafteten Flächen zu verstehen. Die Bestandesstruktur und -entwicklung von subalpinen Fichtenwäldern (Picea abies L.) wurde bereits intensiv untersucht; über Entwicklungsprozesse in zentralalpinen Bergföhren- (Pinus montana Miller) und Arven-/Lärchenwälder (Pinus cembra L./Larix decidua L.) ist hingegen nur wenig bekannt. Der seit 1914 vom Menschen nur noch touristisch genutzte Schweizerische Nationalpark (SNP) ist eines der wenigen Gebiete in Westeuropa, welches über längere Zeit nicht bewirtschaftet wurde. Der Park bietet daher die einzigartige Möglichkeit, die Veränderungen in Bestandesstruktur und -zusammensetzung nach Bewirtschaftungsaufgabe zu beobachten. Wir verglichen historische (1957) und aktuelle (2001/02) Daten von 19 Beständen, welche zu drei verschiedenen Bestandestypen gehören: Bergföhre, Mischbestand und Arve. In den letzten 45 Jahren nahm die totale Stammzahl in allen drei Bestandestypen um 45 bis 57% und die Jungbaumzahl pro Hektar um 64 bis 76% signifikant ab, was vor allem auf den starken Rückgang der lichtbedürftigen Bergföhre zurückzuführen ist. Parallel zu dieser Entwicklung, nahm die Menge an liegendem Totholz in allen Bestandestypen von weniger als 4t/ha auf 36 bis 67,7t/ha zu, während die Anzahl toter Bäume pro Hektar um 72 bis 94% abnahm. Die Biomasse des stehenden Totholzes (t/ha) hat sich hingegen nur leicht verändert. Unsere Resultate beschreiben die sukzessionale Entwicklung von subalpinen Wäldern der Zentralalpen und zeigen, wie sich Wälder in ähnlichen Berggebieten in der nahen Zukunft entwickeln könnten.

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Summary:   Since traditional agriculture and forestry are no longer economically viable in many regions of the European Alps, subalpine forests will become less managed or completely abandoned in the near future. Therefore, the interest in understanding how forest stands will develop after abandonment has increased considerably over the past two decades. While much is known about stand structure and stand development of Norway spruce (Picea abies L.) forests, almost no knowledge is available about the same processes in forest communities of the Central Alps. In the Swiss National Park (SNP), the forested area is comprised of mountain pine (Pinus montana Miller), Swiss stone pine/larch, (Pinus cembra L./Larix decidua L.). and mixed stands. When the Park was founded in 1914 all management activities were stopped. Therefore, this area offers the opportunity to study stand development and changes in stand structure after abandonment. We compared historic (1957) and present data (2001/02) from 19 stands that were grouped into characteristic stand types: mountain pine, mixed, and stone pine. We detected significant decreases in total tree density (stem/ha) and sapling density (saplings/ha) of 45 to 57%, and 64 to 76%, respectively, over the 45 years of observation for all stand types. These changes were strongly related to decreases in the number of shade intolerant mountain pine trees. Simultaneously, the amount of non-standing woody residue increased from less than 4t/ha to 36 to67.7 t/ha, and the density of standing dead wood (stems/ha) decreased significantly between 72 and 94%. The biomass of standing dead wood (t/ha), however, changed only slightly between 1957 and 01/02. Our results describe the successional development of continental subalpine forests after abandonment and outlines changes that might take place in similar areas in the near future.

     

The tolerance of Pinus patula × Pinus tecunumanii, and other pine hybrids, to Fusarium circinatum in greenhouse trials

The field survival of Pinus patula seedlings in South Africa is frequently below acceptable standards. From numerous studies it has been determined that this is largely due to the pitch canker fungus, Fusarium circinatum. Other commercial pines, such as P. elliottii and P. taeda, show good tolerance to this pathogen and better survival, but have inferior wood properties and do not grow as well as P. patula on many sites in the summer rainfall regions of South Africa. There is, thus, an urgent need to improve the tolerance of P. patula to F. circinatum. Operational experience indicates that when P. patula is hybridized with tolerant species, such as P. tecunumanii and P. oocarpa, survival is greatly improved on the warmer sites of South Africa. Field studies on young trees suggest that this is due to the improved tolerance of these hybrids to F. circinatum. In order to test the tolerance of a number of pine hybrids, the pure species representing the hybrid parents, as well as individual families of P. patula × P. tecunumanii, a series of greenhouse screening trials were conducted during 2008 and 2009. The results indicated that species range in tolerance and hybrids, between P. patula and these species, are intermediate in tolerance to F. circinatum. Within P. patula × P. tecunumanii, large family variation exists when pollen from the high elevation source of P. tecunumanii is used. The results of these studies illustrate the importance of developing pine hybrid breeding programs to overcome the susceptibility of our pure species to pathogens such as F. circinatum.     

Fire Burning Characteristics, Attacking Techniques and Safety Precautions in Pinus pumila Scrubs

In China, Pinus pumila is mainly distributed in Daxing’anling, while those growing in the eastern Daxing’anling are primarily covered under the jurisdiction of Huzhong Forest Bureau. P. pumila is an evergreen shrub, 3-6 m high, and always grows vigorously. Its trunks creep along the ground, usually 10 m long or more. It is easily flammable because of the large amounts of resins and volatile oils in its body. Attacking forest fires is a dangerous work, especially in P. pumila scrubs. The fires in P. pumila scrubs are very different from those in other forest types, e.g. fierce combustion and heavy smoke. In this paper, the distribution characteristics of P. pumila scrubs were presented. Attacking techniques and safety precautions for attacking fires in P. pumila scrubs were also discussed.     

Height growth recovery and crown development in top‐damaged Pinus sylvestris trees

Leader shoot damage was imposed on young Scots pines (3 m high) in four ways: by caging the uppermost whorl including the leader shoot with 10 pine shoot beetles; by caging the two uppermost whorls with 20 beetles; by topping the tree below the 1984 whorl; by topping the trees as above and removing all current shoots in whorl 1983. Six years later, top‐damaged trees were still significantly shorter than undamaged controls, although the annual height growth rate had recovered to the pre‐damage level within 3 years. Recovery occurred in two ways: lateral branches from the nearest intact whorl took dominance over the damaged leader or secondary branches developed from interfascicular buds on the damaged leader shoot. Approximately one and two years of height growth were lost in the former and latter case, respectively. Only 5 of the 34 top‐damaged trees escaped technical defects (crooks and/or vertical branches). Stem diameter and crown development were slightly affected.     

加勒比松(Pinus caribaea Morelet)和湿地松(Pinus elliottii Engelmann)

描述形态: 在墨西哥湾周围、安的列斯群岛,以至尼加拉瓜东北部,有俗称《斯拉许松》(Slash Pines)的三叶松。中乔木或大乔木,高15～30米,径30～100厘米,枝下高12米或超过之。叶浓密,冠呈锥状,生长盛期枝斜向上生长;老龄植株枝平展,树冠则呈圆形。幼树树皮灰色,较光滑,成龄树皮逐渐变厚,转为红棕色或橙色,并呈大而薄的长方块状开裂和剥落。     

Comparison of litterfall production in three forest types in Jeju Island,South Korea

Litterfall, which is influenced by physical and biological factors, is a major pathway for carbon and nutrient cycling in forest ecosystems. The purpose of this study was to investigate monthly litterfall production in three forests in Jeju Island differentiated by forest composition and precipitation: Cheongsu(Quercus glauca as the dominant species;low precipitation), Seonheulb(Q. glauca as the dominant species;high precipitation), and Seonheulm(Q. glauca and Pinus thunbergii as the dominant species;high precipitation). Litterfall was collected monthly from April to December 2015 and divided into leaf litter, twig, bark, seeds, and unidentified materials.Seasonal patterns of litterfall production varied across stands according to their species composition. However,the amount of leaf litterfall and total litterfall were comparable among stands, ranging from 362 to 375 g m-2 for leaf litter and 524 g m-2 to 580 g m-2 for total litterfall.Oak leaf litter in May was the highest in all stands, while needle litter was the highest in December in Seonheulm.High twig litterfall in July may be attributable to high rainfall with strong winds and storms during the rainy season. Although forest type and climate factor had no influence on litterfall amounts in this study, the pattern of litterfall production was species dependent, suggesting diverse effects on carbon and nutrient cycling in these forests.     

‘Climatic factors control rodent seed predation in Pinus pinea L. stands in Central Spain’

? Context

Pinus pinea L. presents serious problems of natural regeneration in managed forest of Central Spain. The species exhibits specific traits linked to frugivore activity. Therefore, information on plant–animal interactions may be crucial to understand regeneration failure.

? Aims

Determining the spatio-temporal pattern of P. pinea seed predation by Apodemus sylvaticus L. and the factors involved. Exploring the importance of A. sylvaticus L. as a disperser of P. pinea. Identifying other frugivores and their seasonal patterns.

? Methods

An intensive 24-month seed predation trial was carried out. The probability of seeds escaping predation was modelled through a zero-inflated binomial mixed model. Experiments on seed dispersal by A. sylvaticus were conducted. Cameras were set up to identify other potential frugivores.

? Results

Decreasing rodent population in summer and masting enhances seed survival. Seeds were exploited more rapidly nearby parent trees and shelters. A. sylvaticus dispersal activity was found to be scarce. Corvids marginally preyed upon P. pinea seeds.

? Conclusions

Survival of P. pinea seeds is climate-controlled through the timing of the dry period together with masting occurrence. Should germination not take place during the survival period, establishment may be limited. A. sylvaticus-mediated dispersal does not modify the seed shadow. Seasonality of corvid activity points to a role of corvids in dispersal.