Pinus Patula Schiede Research Articles

ROOTING OF JUVENILE CUTTINGS OF Pinus patula Schiede ex Schltdl. et Cham. HEDGES

Pinus patula Schiede ex Schltdl. et Cham. is endemic to Mexico and is used in both reforestation programs and in the timber industry due to its fast growth, wood quality, and easy handling. With the advance in genetic breeding programs, there is a need to massively propagate new plants from cuttings. One of the main challenges for this purpose is to know the effect of the age of the mother plant (hedge) on the rooting of cuttings. The younger the plant, the greater the rooting is expected to be. Three ontological ages of P. patula mother plants were compared (7, 10, and 13 months). The experimental design was in complete random blocks, with four replications and 25 cuttings per experimental unit. The response variables were evaluated 20 weeks after the experiment was established. No significant differences were observed in the rooting of the three ages evaluated (67.3 to 81 %), nor in the quality of the root (number and length of primary roots, percentage of plants with secondary roots). The results point out an advantage for the propagation of Pinus cuttings since the mother plants at those ages are capable of generating juvenile cuttings that are adequate to obtain percentages of rooting of over 75 %.

The impact of site on tree form, wood properties, and lumber quality of plantation-grown Pinus patula

Abstract South Africa is a water scarce country with minimal natural forests. Plantation forest species such as the Mexican tropical hard pine, Pinus patula Schiede & Deppe ex Schltdl. & Cham., was introduced into the country to satisfy local fibre demand. Today, the majority of pine plantations in South Africa are found in the Mpumalanga province. The province has diverse growing conditions in relation to climate and soil properties. Sample plots were established in even-aged P. patula plantations and stratified according to soil parent material and altitude. Growing conditions of each sample plot were characterised according to climate and soil properties. A total of 540 sample trees were measured for height, diameter, density, and latewood content. The sample trees were harvested to produce 2690 logs. The logs were milled, and the resultant lumber was graded according to density, dynamic modulus of elasticity, and modulus of rupture. Annual maximum temperature had the most significant impact on tree growth, while rainfall correlated with wood density and latewood content of standing trees. However, annual maximum temperature and tree height had a negative relationship with the recovered lumber properties and dimensional stability. Spring rainfall appeared to be the most important factor influencing lumber twist and this was possibly due to the associated larger juvenile core present in the trees.

Almacenamiento de carbono en etapas de crecimiento de Pinus patula Schiede ex Schltdl. & Cham. en la Sierra Alta Hidalguense

Introduction: Forests provide environmental goods and services associated with the forest ecosystem, such as carbon sequestration, which has market potential to contribute to profitability and sustainability of forestry activities. Objective: To estimate biomass and aboveground carbon during the development stages of a Pinus patula Schiede ex Schltdl. & Cham. forest, cultivated in the ejido Atopixco, Zacualtipán, Hidalgo, to know the potential of the species for climate change mitigation. Materials and methods: Aerial biomass was estimated by non-destructive method, using direct measurement of height and diameter at breast height. The volume estimated for the trees sampled, at each stage of development, was multiplied by the basic wood density and the carbon coefficient of 50 % was used. Results and discussion: The average biomass of mature trees was 294.8 kg. Estimates of aboveground carbon at the developmental stages of P. patula were as follows: brinzal (0.94 Mg C·ha-1), monte bravo (3.73 Mg C·ha-1), vardascal (5.05 Mg C·ha-1), latizal (18.18 Mg C·ha-1) and fustal (81.40 Mg C·ha-1). The non-destructive method allowed reliable estimates of carbon content of this species. Conclusion: Carbon storage quantification by stages of development of P. patula is useful marketing strategies of environmental services for carbon sequestration, which has imminent market potential to mitigate the impacts of climate change.

Carbon content and sequestration in Pinus patula Schiede ex Schltdl.&Cham. plantation, in the ejido Rancho Nuevo Nanacamila,Zacatlan de las Manzanas, Puebla, Mexico

Forest plantations represent one of the main mitigation alternatives to climate change due to carbon stores in biomass and soil. Inpresent work the estimation of biomass and carbon stores was carried out in a plantation of Pinus patula Schiede ex Schltdl. &Cham. Location of the site was the Rancho Nuevo Nanacamila ejido in the Zacatlán de las Manzanas municipality, Puebla. Fiveplots of 33 x 33 m were established in order to verify distances between trees in the field. Allometric equations were used to knowthe volume gained during its growth in 2017 and 2018, and the aerial biomass was estimated to calculate the present carbon content.As a result, a total of 1,580 trees were measured whose diameters ranged from 0.5 to 27.9 cm. The average biomass calculation was3,841 t ha. Because the growth of trees is relatively slow, the most effective way to fix COis through proper forest management,harvesting at the best time and turning wood into durable products that allow to store carbon for a long period of time.

Fertilización de dos grupos genéticos de Pinus patula Schiede ex Schltdl. & Cham. en un ensayo de progenies de cuatro años

Introduction: Genetic improvement and nutritional management are used to increase productive capacity. Objective: To analyze the effect of traditional and controlled-release fertilizers, as well as the way to define the doses (technically or empirically), on growth of 20 tree families of Pinus patulaSchiede ex Schltdl. & Cham. Materials and methods: Four fertilization treatments were applied: 1) control; 2) “technical”, based on foliar analysis; 3) controlled release (18-6-12 + 2CaO + 3.5 Mg + 2.1 Si + microelements); and 4) mixture of agricultural fertilizers in nutrient concentrations similar to the controlled-release treatment. Height, diameter, biomass index, number of whorls, leaf mass, and growth initiation and cessation were evaluated in a group of 10 superior and 10 inferior three-year old families in Chignahuapan, Puebla. Data were analyzed with the MIXED procedure of SAS. Results and discussion: Trees showed no significant differences in growth, biomass production and growth initiation by fertilization effect, but showed significant differences by genetic quality (P ≤ 0.05). The genotype*fertilization interaction was significant; after one year of controlled-release fertilizer application, inferior genotypes had the highest values of relative rates of biomass production, diameter at root collar and height. Conclusions: Controlled-release fertilizers at appropriate doses and environmental conditions are a viable option to promote growth of young P. patula trees in the field.

ALLOMETRIC EQUATIONS FOR BELOWGROUND BIOMASS AND CARBON CONTENT OF Pinus patula SCHL. et CHAM.

Allometric equations are essential tools for estimating biomass and carbon fixation in forest ecosystems. Published information is limited for belowground biomass of forests, mainly due to the methodological challenges of its determination. With the aim of contributing to the study of this important carbon store, in the present study allometric equations were developed for the estimation of belowground biomass of Pinus patula Schiede ex Schldl. et Cham. in its main natural distribution area: the states of Hidalgo, Puebla and Veracruz, Mexico. Seven Pinus patula trees with varying dimensions were selected and torn down at various sites; their diameter at breast height (DBH), total height (H), and crown diameter (CD) were measured. The totality of fine and coarse roots was extracted; the aboveground biomass was quantified by census, by sampling or by means of an allometric equation. Equations were developed for belowground biomass and carbon content, both total and by components, aswell as for individual root, both total and by components. The average root/ shoot ratio was 0.20 and the proportion of belowground in relation to the total biomass ranged from 12.1 to 21.2 %. The data on belowground biomass and carbon content at the tree level better fitted the Schumacher and Hall model that included both DBH and H as independent variables, which explained 99 % of the variation of belowground biomass and carbon. It was concluded that it is possible to use allometric equations to estimate the belowground biomass and carbon of Pinus patula trees from DBH and H, or even using only DBH.

Grasses as a refuge for Fusarium circinatum L. – evidence from South Africa

Fusarium circinatum L. is an important pathogen in countries that grow and manage Pinus species. Approximately 50% or 600 000 ha of South Africa’s commercial plantations are planted to Pinus spp. and some of these are threatened by this fungus. Contaminated plants, planting trays, soil and water can all act as sources of inoculum. In this study, we considered the role of grasses as a possible source of inoculum for F. circinatum-associated disease of Pinus in South Africa. Isolates of F. circinatum were collected from grasses in the understories of pitch-canker affected stands of Pinus radiata D.Don and Pinus patula Schiede ex Schltdl. & Cham. in the Western Cape and Limpopo provinces, respectively. The mating types and microsatellite-based genotypes of the isolates were then compared with those in collections of this pathogen associated with pitch-canker on P. radiata and P. patula in the respective regions. The results showed that the F. circinatum isolates from grass originated from inoculum produced from stem and branch cankers on the trees above the grasses. The discovery of F. circinatum from five grass species in Limpopo increases the total number of known grasses associated with the fungus to nine in South Africa and seventeen globally. All of the F. circinatum isolates recovered from grass in South Africa displayed levels of aggressiveness to P. patula seedlings that were comparable with those of an isolate used for routine screening of commercial planting stock. The data also suggest that grass might influence the expression of disease caused by F. circinatum on Pinus. This was because a specific genotype of the pathogen originating from grass was less aggressive on P. patula seedlings than its counterpart from diseased Pinus. Taken collectively, the results indicate that phytosanitary practices for the management of F. circinatum should include grass as a significant source of inoculum, and this should be an important quarantine consideration, both nationally and internationally.

Soil Fungal Communities under Pinus patula Schiede ex Schltdl. & Cham. Plantation Forests of Different Ages in Ethiopia

The cultivation of plantation forests is likely to change the diversity and composition of soil fungal communities. At present, there is scant information about these communities in Ethiopian plantation forest systems. We assessed the soil fungal communities in Pinus patula Schiede ex Schltdl. & Cham. stands aged 5, 11, or 36-years-old using DNA metabarcoding of ITS2 amplicons. The ecological conditions of each plot, such as climate, altitude, and soil, were similar. Stand age and soil fertility influenced soil fungal species diversity and ecological guilds. In total, 2262 fungal operational taxonomic units were identified, of which 2% were ectomycorrhizal (ECM). The diversity of ECM fungi was higher in the 5 and 36-year-old stands than in the 11-year-old P. patula stands. Contrary to our expectations, a high level of ECM species diversity was observed in young stands, suggesting that these ECM species could compensate for the effects of nutrient stress in these stands. Our results also suggested that the abundance of plant pathogens and saprotrophs was not affected by stand age. This study provides baseline information about fungal community changes across tree stands of different ages in P. patula plantations in Ethiopia that are likely related to ECM fungi in young stands where relatively low soil fertility prevails. However, given that the plots were established in a single stand for each age class for each treatment, this study should be considered as a case study and, therefore, caution should be exercised when applying the conclusions to other stands.

The flexural lumber properties of Pinus patula Schiede ex Schltdl. & Cham. improve with decreasing initial tree spacing

An increase in the stiffness of lumber with a decrease in initial tree spacing was confirmed for Pinus patula Schiede ex Schltdl. & Cham. The underlying properties of microfibril angle, wood density and knot frequency explained 71% of the variation in lumber stiffness. Tree spacing also influenced wood properties independent of radial growth rate. Rapid growth rates and reduced harvesting ages of South African-grown pine plantations have caused a reduction in the stiffness of structural lumber, which accounts for about 75% of all sawn wood. Microfibril angle and wood density are known to influence wood stiffness, which may be manipulated by the growing space of trees. The objective of this study was to evaluate the effect of slower growth rates, caused by narrow tree spacing, on the suitability of Pinus patula Schiede ex Schltdl. & Cham. wood for structural lumber. An 18- and a 19-year-old spacing experiment with four levels of initial tree spacing (1.83 m × 1.83 m, 2.35 m × 2.35 m, 3.02 m × 3.02 m and 4.98 m × 4.98 m) were sampled. Linear and non-linear mixed-effects models were developed to examine the effect of tree spacing on the quality of wood and lumber as defined by the modulus of elasticity, modulus of rupture and knot frequency of 208 boards and the ring-level microfibril angle and wood density of 86 radial strips. Wood and lumber quality improved with decreasing spacing, and only the narrowest spacing had lumber that conformed to the requirements of the lowest South African structural grade. Microfibril angle, wood density and knot frequency explained 71% of the variation of lumber stiffness. After accounting for ring width differences, there remained a significant effect of initial spacing on the parameters of models predicting microfibril angle and wood density. Wide initial spacing is discouraged if higher strength grades are desired for Pinus patula lumber.

Allometric equations to estimate aboveground and belowground biomass of Pinus patula Schiede ex Schltdl. & Cham

The estimation of tree biomass serves as a parameter of forest productivity; in addition, it is a method to estimate carbon fixation and storage. Studies on total biomass that include the belowground component for the Pinus genus are scarce in Mexico due to the difficulty and high costs for its quantification. In this study, allometric models were fitted to estimate the total biomass of Pinus patula Schiede ex Schltdl. & Cham., from the pine-oak forest of Ixtlán de Juárez, Oaxaca, for which a destructive analysis was made of 25 trees distributed in five diameter classes, classifying the biomass by components (root, stem, branches and foliage). With the component biomass data, different models were fitted by nonlinear regression techniques, using the diameter at breast height (D, cm) and the total height (TH, m) as independent variables. The model with the best fit was an exponential type In this study, it was observed that the studied species stores 22.62% of the biomass in the root, 69.61% in the stem, 5.67% in the branches and 2.11%, in the foliage. The models proposed in this study allow the estimation of total biomass and by structural component independently and additively. Its use is recommended in trees of P. patula, in the range of 5 to 25 cm of diameter at breast height, in forests with similar growing conditions.

CRECIMIENTO RADIAL Y CONICIDAD DEL FUSTE EN PLANTACIONES CON ACLAREO DE Pinus patula SCHIEDE ex SCHLECHTENDAL & CHAMISSO

Pinus patula Schiede ex Schlechtendal & Chamisso es una especie endémica de México, con gran relevancia económica por su alto potencial productivo en plantaciones forestales y bosques naturales. La intensidad y frecuencia de las cortas de aclareo generalmente influyen en el grueso de los anillos anuales de crecimiento, la proporción de madera tardía y la conicidad del fuste. El objetivo del presente estudio fue evaluar el crecimiento radial y el grueso de los anillos de crecimiento y de sus componentes de madera temprana y tardía a diferentes alturas del fuste, así como el índice de conicidad del fuste en plantaciones jóvenes de Pinus patula con cortas de aclareo aplicadas a los nueve y 13 años de edad. Se seleccionaron y derribaron 10 árboles por parcela con diámetro normal similar al valor promedio de éstas, para obtener tres secciones transversales (rodajas) de 3 cm de grueso a diferentes alturas de cada árbol muestreado. Las cortas de aclareo causaron un impacto reducido en el grueso de los anillos anuales y sus componentes de madera temprana y tardía en la sección basal. El efecto de la corta se presentó sólo al año siguiente de su aplicación, con incrementos en el área basal y en el grueso de madera temprana; después, el ritmo de crecimiento radial regresó a su patrón original. El grueso de los anillos y de la madera temprana y tardía fue mayor en la parte intermedia y superior del fuste, lo que ocasionó una reducción gradual en la conicidad, lo cual corroboró que la aplicación de las cortas de aclareo fueron tardías, cuando la copa ya se había concentrado en la parte superior del árbol, por la elevada competencia por espacio de crecimiento.

PROPAGACIÓN VEGETATIVA DE Pinus patula SCHIEDE ex SCHLTDL. et CHAM. EN DIFERENTES SUSTRATOS

Pinus patula Schiede ex Schldl. et Cham. es una especie endémica de México utilizada en plantaciones forestales comerciales en Sudamérica y Sudáfrica. La propagación masiva de materiales mejorados de esta especie, a través de estacas enraizadas, permite aumentar su productividad y homogeneizar sus productos. Se compararon cinco sustratos a base de aserrín fresco y corteza de pino en diferentes proporciones (1:9, 3:7, 5:5, 7:3 y 9:1 v:v) para evaluar el enraizamiento de estacas de esta especie forestal. Se utilizó un diseño experimental de bloques completos al azar con cuatro repeticiones; la unidad experimental estuvo conformada por 25 estacas. Se analizaron las principales características físicas y químicas de los sustratos tales como porosidad total, porosidad de aireación, retención de humedad, densidad aparente, pH, conductividad eléctrica y capacidad de intercambio catiónico al inicio y al final del experimento. Las variables evaluadas fueron la supervivencia, enraizamiento, presencia de callo, número y longitud de raíces primarias y presencia de raíces secundarias a las 20 semanas de establecido el experimento. El sustrato con la mayor proporción de aserrín (9:1) presentó el porcentaje de enraizamiento de las estacas más elevado (77 %), en comparación con el testigo (1:9), donde se obtuvo 42 %. Se observó alta correlación (0.97, 0.97, 0.90) del enraizado con el porcentaje de aserrín, densidad aparente y pH, respectivamente. La mezcla de aserrín y corteza de pino (9:1) presentó características físicas y químicas apropiadas para la formulación de sustratos útiles para propagar P. patula mediante el enraizado de estacas.

Priorities for Conservation and Sustainable Use of Forest Genetic Resources in Four Mexican Pines

The strategies for the conservation and sustainable use of forest genetic resources, which are essential for the future adaptation of forest species to changing environments, are also a source of valuable genetic resources for breeding and restoration activities. The first step to define and implement cost-effective strategies is to identify specific priority populations. Mexico, in spite of being characterized by high levels of tree species diversity, mostly lacks a combined strategy for the genetic conservation and use of forest genetic resources. The aims of this work are: (i) to identify areas for gene conservation, and (ii) to propose measures for the conservation and sustainable use of forest genetic resources of four pine species: Pinus greggii Engelm. ex Parl., Pinus oocarpa Schiede ex Schltdl., Pinus patula Schiede ex Schltdl. & Cham. and Pinus pseudostrobus Lindl. To do that, we use the existing information on the distribution, genetic variation and conservation and breeding efforts in Mexico. Overall, 51 areas for establishing genetic conservation units were prioritized and 6 genetic zones for the use of forest genetic resources in breeding and selection of forest reproductive material were identified. The current conservation efforts for the four priority Mexican pines should be improved to satisfy the needs of a national breeding and conservation network.

Frost tolerance of various Pinus pure species and hybrids

Pinus species are widely planted by the South African forestry industry and are utilised for pulp, paper and saw timber products. Historically, Pinus patula Schiede ex Schltdl. et Cham. was the most widely planted commercial species in the summer rainfall area, but has come under severe threat due to the fungus Fusarium circinatum. Fusarium circinatum causes mortality in nurseries and in-field after establishment. Other Pinus species, such as P. tecunumanii F.Schwerdtf. ex Eguiluz et J.P.Perry and P. oocarpa Schiede ex Schltdl., have been crossed with P. patula to increase tolerance to F. circinatum and these hybrids have largely overcome the post-planting mortality problem. However, these hybrid-partner species are more prone to frost damage. This study reviewed laboratory screening techniques to assess the frost tolerance level of a range of Pinus pure species and hybrids. In vitro screening was done with the electrolyte leakage and whole-plant freezing techniques. Seedlings and rooted cuttings from a range of genotypes, supplied by Sappi, were tested in vitro at different target temperatures (−3, −6, −9 and −12 °C) to determine their relative frost tolerance. These genotypes included a range of Pinus pure species, four interspecific hybrids (P. patula × P. tecunumanii low elevation [LE], P. patula × P. tecunumanii high elevation [HE], P. elliottii Engelm. × P. caribaea Morelet), and a three-way cross (P. patula × (P. patula × P. oocarpa)). Results from this study indicated that the electrolyte leakage technique was a reliable method to determine frost tolerance under laboratory conditions, with similar pure species rankings as experienced under field conditions. The interspecific hybrids of P. patula × P. tecunumanii LE and HE ranked intermediate between the parental species and the P. patula × P. tecunumanii HE hybrid was more frost tolerant than the P. patula × P. tecunumanii LE hybrid.

The importance of harvest residue and fertiliser on productivity of Pinus patula across various sites in their first, second and third rotations, at Usutu Swaziland

BackgroundConcern is growing about the future of forestry productivity due to intensive nutrient removal, as a result of different harvesting operations. This study aimed to determine the effects on forest productivity when using different slash-retention scenarios with the recommended amounts of mineral fertiliser in Usutu forest. Usutu is a plantation forest that grows mostly softwood where the predominant species is Pinus patula Schiede ex Schltdl. & Cham.MethodsThe first trial series (F) comprised of one trial located in each of five forest blocks. It was established in 1971 and compared the effects of various site preparation scenarios (slash removal, slash retention and cultivation) on the early growth of Pinus patula for adjacent first (F1R) and second rotation (F2R) sites (i.e. grassveld and clearfelled first-rotation sites). The second (S) trial series was re-established in April 1991 on exactly the same position as the first trial series, and involved second (S2R) and third rotation (S3R) sites. Three main treatments, standard pitting through harvest residue (control); manual pitting after removal of harvest residue and forest floor (cleared); and manual pitting and broadcast application of dolomitic lime (2 t ha− 1) over the slash (lime), were undertaken in factorial combination with the application of phosphate and potassium fertiliser. The data reported here are for tree volume productivity across the five sites of the first trial series up to age 10 years and three of the five sites of the second trial series up to age 9 years.ResultsSlash removal decreased volume productivity by 9 and 13% in the F1R and F2R at 10 years of age and further by 21 and 33% in S2R and S3R, respectively at 9 years of age. However, fertiliser application increased volume productivity by 14 and 15% in the F1R and F2R at 10 years age and further by 18 and 10% in the S2R and S3R, respectively at 9 years of age.ConclusionsIn order to sustain or increase productivity, it is recommended that harvest residue slash should be conserved and fertiliser containing phosphate and potassium be applied at planting at Usutu.

Impacts of under-canopy vegetation on stand growth in two pine saw-timber stands, South Africa

BackgroundIn pine plantations, shading following canopy closure reduces the growth of competing vegetation. However, canopy closure is not always achieved if low initial planting density, pruning and thinning are practised. This means that complete shading does not occur, resulting in stands with potentially competitive levels of under-canopy vegetation.MethodsAt the time of the first pruning operation, two trials were established to determine the competitive effect of under-canopy vegetation on pine tree growth in South Africa, one on a Pinus patula Schiede ex Schltdl. & Cham. (4.5 years) and one on a Pinus tecunumanii F.Schwerdtf. ex Eguiluz & J.P.Perry (2.9 years) stand. This paper documents results at the final thinning operation carried out at 17–18 years. Treatments were weedy (no vegetation control), herbaceous (complete sustained control of woody vegetation), woody (complete sustained control of herbaceous vegetation), weedfree (complete sustained control of all competing vegetation) and operational (only the woody perennial broadleaves were removed prior to any pruning/thinning event in the commercial weed control treatment). From the time vegetation management treatments were first imposed, they were maintained and tree performance monitored over 14–15 successive growing seasons, including and up to the second and final thinning to 250 stems ha−1.ResultsThe presence of vegetation for up to 15 years had no significant impact on the volume of P. patula and P. tecunumanii following two thinning operations (813 to 400 stems ha−1; 400 to 250 stems ha−1). For P. patula, but not P. tecunumanii, there was a significant and negative impact of under-canopy vegetation on the total basal area removed during two thinning operations. This may result in a reduction in the selection of stems to remain following thinning, as well as any profit that may be obtained if the thinnings were of commercial value.ConclusionsFor the species (P. patula and P. tecunumanii) and sites tested, the results indicate that if good establishment weed control is carried out (from planting until the first pruning event), the development and subsequent impact of under-canopy vegetation over the subsequent 14–15 years (between the first pruning event and the final thinning to 250 stems ha−1) on the growth of the remaining stems is negligible.

Parasitoid assemblage associated with a North American pine weevil in South Africa

Abstract The weevil Pissodes sp. was first reported as an introduced pest on exotic Pinus spp. in South Africa in 1942. It is only recently that the native wasp Pycnetron pix Prinsloo was described from South Africa as a parasitoid of this weevil. We estimated the frequency and distribution of the association between P. pix and Pissodes sp., as well as the occurrence of possible other natural enemies. Parasitoids were reared from Pissodes‐infested Pinus radiata D. Don and Pinus patula Schiede ex Schltdl. & Cham logs collected from major Pinus‐growing regions. The identity of parasitoids was confirmed using morphological and molecular techniques. Parasitism was confirmed by analyzing gut content sequences of parasitoids. Pycnetron pix was found parasitizing Pissodes sp. throughout major Pinus‐growing provinces of the country. Another native parasitoid, Cratocnema sp., is reported for the first time as a parasitoid of Pissodes sp. Rhopalicus tutela (Walker), a known parasitoid of Pissodes spp. in their native range, was also detected and confirmed to be of European origin. Although characterized by an erratic distribution and a low parasitism rate, an accruing suite of natural enemies was documented, suggesting that there is potential for augmentative biological control of Pissodes sp. in South Africa.

Fungal diversity and succession following stand development in Pinus patula Schiede ex Schltdl. & Cham. plantations in Ethiopia

Fungal communities associated to conifers have been typically studied in temperate conifer forests, but little is known about tropical habitats. The present study examined the macrofungal succession and corresponding sporocarp production in Pinus patula stands in Ethiopia. For this purpose, we surveyed nine permanent plots (100m2) established in five-, eleven- and thirty-six years old P. patula plantations and estimated fungal taxa richness, diversity and sporocarp yields. Composite soil samples were also collected from each plot to determine explanatory edaphic variables for fungal taxa compositions. We found a total of 53 fungal taxa belonging to Basidiomycota, with the exception of Xylaria hypoxylon which is Ascomycota. The majority of the collected taxa were saprophytic and about 6% were ectomycorrhizal fungi. About 36% of the taxa were classified as edible. Taxa richness, the Shannon diversity index and sporocarp yields showed significant increasing trends towards the more mature P. patula stands. Fungal community composition was also correlated significantly with N, K, and pH. This study extends our knowledge on fungal diversity and community structure in managed P. patula plantations. Higher diversity and sporocarp production was found in older stands. Thus, the deliberate presence of mature trees in Pinus stands could provide incentives for the production and conservation of ecologically and commercially important fungal species in the study area.

Growing common plantation tree species in Kenya for sale of carbon and wood supply: what is the best bet?

The introduction of carbon finance as an incentive in forestry farming has a potential of increasing the amount of carbon sequestered. However, this has created a daunting task among investors in forestry to optimise the joint production of wood and carbon sequestration. For instance, investors might find it profitable to give up some timber returns in exchange for carbon credits. This study evaluated expected income from growing Cupressus lusitanica Mill., Pinus patula Schiede ex Schltdl. & Cham., Eucalyptus saligna Sm. and Juniperus procera Hochst. ex Endl. for wood and/or the carbon market in central Kenya. The global average unit price of carbon and stumpage royalty were used to estimate expected returns from sale of carbon credits and wood, respectively. There were significant differences (p < 0.01) in the expected amount of income from sale of carbon and wood among the four species. Specifically, at economic rotation of 30 years with stand density of 532 trees ha−1 P. patula and C. lusitanica yielded US$28 050 and US$23 650, respectively, from sale of carbon compared with US$59 000 and US$51 000, respectively, from sale of wood. This was twice the value investors receive from clear-felling as compared with sales from carbon. Similarly, at economic rotation of 33 years with stand density of 150 trees ha−1, a forest investor in E. saligna would earn US$15 400 from sale of carbon compared with US$33 000 from sale of wood. Overall, the amount expected to be realised from sale of carbon was lower compared with that from sale of wood. This demonstrates that the price dynamics of carbon offsets in the voluntary and the compliance markets need to remain competitive and attractive for the forest owners to give up some timber returns in exchange for carbon income or to modify forest management regulation in order to increase carbon sequestration.

Effect of giberellic acid (GA4/7) and girdling on induction of reproductive structures in Pinus patula

Aim of study: Seed production in forest tree species commonly takes a long time due to the length of the juvenile stage. Even though several treatments have been used to induce early flowering in conifer species, experience on their use in subtropical Pinus species is limited. This study aimed to evaluate the effect of GA4/7 dose (0, 1.27 and 2.54 mg cm-2) and application time (July-October), alone or in combination with partial stem girdling, on male and female strobili production in young Pinus patula Schiede ex Schltdl. et Cham. clones. Area of study: Nine clones with different flowering background of high-elevation Pinus patula growing in a six-year old seed orchard established in Central México (Aquixtla, Puebla) at 2,800 m elevation.Material and methods: Two independent flowering trials (FT1 and FT2) were carried out in the seed orchard during the 2009 and 2010 flowering cycles; similar factors were evaluated at both trials but time of application, clones tested, and experimental design used varied for each of them. Partial stem girdling was done at the base of the trunk and the GA4/7 solution was injected into the xylem above the point of girdling. The following spring, the percentage of trees with strobili and the number of strobili per tree were determined for both male and female structures.Main results: Significant differences (p ≤ 0.05) among clones in flowering capacity were found at both trials. None of the treatments applied in FT1 resulted in an increase of strobili formation, most probably because they were applied too late in the growing season. In FT2, however, application of GA4/7 combined with partial stem girdling increased the percentage of trees with strobili and the number of strobili of both sexes, particularly when applied in early July. Partial stem girdling was more effective on promoting male strobili than female ones in gibberellin-treated grafts.Research highlights: Timing of GA4/7 application and stem girdling was important, with a significant interaction with clones tested in FT2 on production of male strobili but not on female strobili. Application of 1.27 mg cm-2 GA4/7 and stem girdling in July promoted the highest percentage of trees with strobili, and increased 25-fold the number of female strobili and 5-fold the number of male strobili per tree as compared to the control treatment. Thus, operational use of this induction treatment would be valuable to increase and accelerate seed production in Pinus patula seed orchards in the region.Keywords: early flowering; gibberellins; juvenile stage; seed orchard; seed production.Abbreviations: GA: Gibberellic acid; GA4: Gibberellic acid 4; GA7: Gibberellic acid 7; GA4/7: Mix of gibberellic acids 4 and 7; FT1: Flowering trial carried out in the 2009 season; FT2: Flowering trial carried out in the 2010 season.