Pine plantations in south eastern Australia support highly impoverished ant assemblages (Hymenoptera: Formicidae)

Pitfall trap surveys of ants were undertaken in mature and intermediate-aged Pinus radiata plantations and parental eucalypt forest in central Victoria, Australia. Ant assemblages of pine plantations are an impoverished subset of the eucalypt forest assemblages. Very few ant morphospecies, most of them in very low abundance, were found in unthinned intermediate-aged pines, and the numbers were substantially higher in older, thinned pines in which understorey vegetation is considerably more developed. Implications for plantation management and conservation of epigaeic ant assemblages are discussed.     

The productivity of pine plantations in relation to previous land use

Summary The improved growth of pine plantations on pasture soils compared with that on soils which previously supported native eucalypt forest is primarily explained in terms of soil phosphorus. Pasture development has resulted in a decrease in the P adsorption maximum of about 300 g g^–1 soil, a figure which agrees with the increase in total P due to the application of superphosphate. P adsorption isotherms were used to calculate additions of P to give comparable levels of soil solution P in eucalypt and pasture soils. The growth of pine seedlings in soils thus amended showed a strong N×P interaction. When P was non-limiting, addition of N raised productivity of the eucalypt soil above that of the pasture soil. It is postulated that the different nature of the N×P interaction in eucalypt and pasture soils results from differences in the nitrogen cycle in the two soils.     

Stem deformity inPinus radiata plantations in south-eastern Australia:

Visual symptoms of stem deformity similar to those of Cu deficiency are common inP. radiata established on fertile sites previously used for agricultural production in south-eastern Australia. In this study, Cu fertiliser was applied at rates of 0, 2, 5, 10, 20 and 50 kg ha⁻¹ to deformedP. radiata at ages 3 and 6 years. Available soil Cu and contents of Cu in the foliage increased significantly only in the younger plantation. Cu fertiliser did not affect growth nor did it improve stem form. Levels of N, Cu and Cu/N ratios in foliage of straight and deformed trees were similar. However, contents of Cu in apical buds were significantly lower in deformed trees. It was concluded that stem deformity inP. radiata as observed on these fertile pasture sites, cannot be corrected by application of Cu fertiliser. Differences in Cu levels in apical buds of straight and deformed trees suggest that Cu may still be involved in this syndrome. There was also no indication of other nutrient deficiencies that could be associated with the deformity.     

Ectomycorrhizal fungi associated with ponderosa pine and Douglas-fir: a comparison of species richness in native western North American forests and Patagonian plantations from Argentina

The putative ectomycorrhizal fungal species registered from sporocarps associated with ponderosa pine and Douglas-fir forests in their natural range distribution (i.e., western Canada, USA, and Mexico) and from plantations in south Argentina and other parts of the world are listed. One hundred and fifty seven taxa are reported for native ponderosa pine forests and 514 taxa for native Douglas-fir forests based on available literature and databases. A small group of genera comprises a high proportion of the species richness for native Douglas-fir (i.e., Cortinarius, Inocybe, and Russula), whereas in native ponderosa pine, the species richness is more evenly distributed among several genera. The comparison between ectomycorrhizal species richness associated with both trees in native forests and in Patagonia (Argentina) shows far fewer species in the latter, with 18 taxa for the ponderosa pine and 15 for the Douglas-fir. Epigeous species richness is clearly dominant in native Douglas-fir, whereas a more balanced relation epigeous/hypogeous richness is observed for native ponderosa pine; a similar trend was observed for Patagonian plantations. Most fungi in Patagonian Douglas-fir plantations have not been recorded in plantations elsewhere, except Suillus lakei and Thelephora terrestris, and only 56% of the fungal taxa recorded in Douglas-fir plantations around the world are known from native forests, the other taxa being new associations for this host, suggesting that new tree + ectomycorrhizal fungal taxa associations are favored in artificial situations as plantations.     

Root development and configuration in intensively managed radiata pine plantations

Summary In south-east Australia, where radiata pine (Pinus radiata D. Don) is grown on sandy soils low in nutrients and short of water, early establishment, and rapid growth to canopy closure lead to increased productivity. At this stage demands for nutrients and water are high, and trees respond vigorously to silvicultural inputs.For several months after transplanting in winter roots are confined within a narrow planting wedge, low temperature restricts new root growth and slows recovery from water stress in plants. From spring, depending upon the configuration and vigour of the roots transplanted, lateral roots extend radially throughout the soil.Although there were small decreases in concentration of roots radially from the stems of very young trees, such spatial differences disappeared between ages 2 and 3, so that rooting density was independent of distance from the stem. The pattern of vertical distribution of lateral roots was not influenced by age and 80–90% of the lateral roots were within the top 30 cm soil. Roots developed rapidly as the trees grew towards canopy closure, but in general the rooting densities of these pines are among the lowest reported for plants. In rapidly growing trees approaching canopy closure, the secondary thickening of the lateral roots was sufficient to double the weight of roots without altering root length.Knowledge about root growth and root configuration during the early phase of plantation development will assist management decisions where intensive silviculture is practiced, and hence ensure the most efficient use of nutrients and water.     

Inferring relatedness and heritability using molecular markers in radiata pine

A set of eight unlinked microsatellite markers was used to estimate relatedness among 355 individuals of a Pinus radiata breeding population. The average performance of open-pollinated progeny of each individual, for wood density, was considered to represent the phenotype of all 355 individuals. Marker-based estimates of relationship were compared with the pedigree-based coefficients of relationships. The phenotypic similarity among all pairs of individuals was regressed on marker-estimated relatedness to estimate the inheritance of wood density. The marker-based estimate of heritability was compared with that obtained using classical quantitative genetic methods. Overall, a low correlation (0.13) was observed between marker-based and pedigree-based estimates of relatedness. After discarding negative estimates of relatedness, the average coefficient of relationship among known groups of maternal half-sibs, full-sibs and unrelated individuals, increased from 0.24 to 0.29 (0.25 expected), from 0.43 to 0.48 (0.50 expected) and from –0.04 to 0.15 (0 expected), respectively. Marker-based and conventional estimates of heritability of wood density were 0.79 and 0.38, respectively. However, by using only marker loci with expected Hardy–Weinberg frequencies, marker-based estimate of heritability was 0.33, which is very similar to that obtained from conventional approaches. The use of molecular markers to understand quantitative genetic variation is discussed.     

无瓣海桑与乡土红树植物混交对林地大型底栖动物的影响

选择广东省雷州市附城镇和珠海市淇澳岛沿海1年生无瓣海桑人工林,分别在林下混种乡土红树植物红海榄或木榄幼苗,对混交林和无瓣海桑纯林林地大型底栖动物群落进行比较,探讨无瓣海桑与乡土红树植物混交对林地大型底栖动物的影响。结果显示,混交林和无瓣海桑纯林之间大型底栖动物群落的优势种存在差异;相似性分析检验(One-Way ANOSIM)、等级聚类和非参数多变量标序结果均表明1年无瓣海桑+红海榄混交林、1年无瓣海桑+木榄混交林和1年无瓣海桑纯林之间大型底栖动物群落结构差异显著。研究还发现在无瓣海桑人工林林下混交红海榄或木榄这两种乡土红树植物,可提高林地底栖动物的生物量和物种多样性。BIOENV分析说明大型底栖动物分布与红海榄或木榄这两种混交的乡土树种的凋落物量密切相关,这进一步证实了混交乡土红树植物对林地底栖动物多样性和分布的影响。两个研究地实验结果均显示,在无瓣海桑林下种植木榄的效果要优于红海榄,表现在木榄的平均苗高、凋落物量、凋落物量占群落凋落物总量百分比和幼苗成活率均高于红海榄,其对提高林地大型底栖动物生物量和物种多样性的效果也明显优于红海榄。     

Evidence for recombination and segregation of virulence to pine in a hybrid cross between Gibberella circinata and G. subglutinans

Two species associated with the Gibberella fujikuroi species complex, G. circinata (the cause of pitch canker in pines) and G. subglutinans (avirulent on pine), were found to have limited interfertility in hybrid crosses. MAT idiomorphs, polymorphisms in the histone H3 gene, vegetative compatibility, and virulence phenotypes were used to verify recombination. The MAT idiomorphs appeared to be assorting independently, but the histone H3 haplotype was disproportionately represented by that of the G. subglutinans parent. Ninety-eight percent (45/46) of the progeny tested were vegetatively incompatible with both parents. All F₁ progeny were avirulent to pine, but a wide range of virulence was restored through a backcross to the virulent parent (G. circinata). Attempts at hybrid crosses using other isolate combinations were rarely successful (1/26). This limited interfertility supports retention of G. circinata and G. subglutinans as separate species, but offers opportunities to characterize the inheritance of virulence to pine.     

Bird assemblages in pine plantations replacing native ecosystems in NW Patagonia

Forest plantations of exotic conifers represent an important economic activity in NW Patagonia, Argentina. However, there is a remarkable lack of information on the impact of forestry on native biodiversity. We analyzed the effect of Pinus ponderosa plantations on bird communities, considering different stand management practices (dense and sparse tree covers), and different landscape contexts where they are planted (Austrocedrus chilensis forest and steppe). Ultimately we wished to assess in which way plantations may be designed and managed to improve biodiversity conservation. Bird richness and abundance did not change significantly in the steppe, although community composition did, and was partially replaced by a new community, similar to that of ecotonal forests. In contrast, in the A. chilensis forest areas, species richness decreased in dense plantations, but bird community composition remained relatively constant when replacing the native forest with pine plantations. Also, in A. chilensis forest, stand management practices aiming at maintaining low tree densities permit the presence of many bird species from the original habitat. In the steppe area in turn, both dense and sparse plantations are unsuitable for most steppe species, thus it is necessary to manage them at higher scales, maintaining the connectivity of the native matrix to prevent the fragmentation of bird populations. We conclude that pine plantations can provide habitat for a substantial number of native bird species, and this feature varies both with management practices and with the landscape context of areas where afforestation occurs.     

Identification of an agar constituent responsible for hydric control in micropropagation of radiata pine

Tissue cultured Pinus radiata grown on media containing agar as the gelling agent display toxic symptoms and poor long-term shoot survival, however it does have the attribute of hydric control, through a mechanism which, until now, has not been elucidated. Gelrite as an alternative gelling agent is clearly non-toxic but results in hyperhydric (vitrified) tissues. In an effort to overcome these problems, the controlling mechanism found in agar was examined. Hydric control was shown to be effected by a non-gelling, cold-water soluble constituent of a commercial agar, rather than by physical properties of the gel. It could be separated from low molecular weight components of the agar responsible for the toxic symptoms by dialysis. It was identified as being an agaroid-type xylogalactan bearing pyruvate and sulphate substituents. Improved management of gelling agents in culture medium has contributed substantially to a thirty fold increase in propagation rates.     

The origin and genetic diversity of Pinus radiata in Australia

Summary Despite the fact that forest trees are in early stages of domestication there has been little direct evaluation of either the origin of, or genetic diversity within the breeding material in tree improvement programs. Allozyme variation was used to compare the total genetic diversity in the breeding programs of P. radiata within Australia and the five wild populations in North America. The current breeding populations were very similar genetically and were essentially homogenous with only 1.8% of the variation among programs. The total genetic diversity in the species was 0.12, which is a low estimate compared to most conifers. Overall in the Australian material the genetic diversity was somewhat less. The comparison of allelic frequencies in the five native populations with the Australian material indicates that the Monterey and Año Nuevo populations were probably the major source of the original introductions and that a substantial portion of the genetic diversity in the two populations has been captured in current breeding programs. The three southern populations do not appear to be currently represented in the breeding programs. The implications for future breeding strategies are discussed.     

13C NMR study of pine needle decomposition

The quality of substrates in plantation forest litter, and their chemistry, can influence decomposition and N cycling. We studied the decomposition of Pinus radiata D. Don needles suspended on branches in windrows, for 3 yr after clear-cutting, using improved solid-state ¹³C NMR and chemical analysis. The NMR spectra suggested that the concentration of condensed tannins was 12–22%, and showed they were chemically altered during the period 4–12 months after clear-cutting. The spectra showed no evidence for further chemical modification of the tannins during the second or third years. Data for P. radiata needle decomposition in New Zealand indicated rapid loss of mass in the first 3 months, and condensed tannins did not appear to prevent mineralization of C or N. The tannin and lignin concentrations increased with decomposition of the needles, which was consistent with the early mineralization of readily available C compounds.     

The red turpentine beetle, <Emphasis Type="Italic">Dendroctonus valens</Emphasis> LeConte (Scolytidae): an exotic invasive pest of pine in China

An exotic invasive pest of pines, the red turpentine beetle, Dendroctonus valens LeConte (Scolytidae) (RTB), was first detected in Shanxi Province, northern China, in 1998 and started causing widespread tree mortality there in 1999. This outbreak continues and has spread to three adjacent provinces, causing unprecedented tree mortality. Although it is considered a minor pest of pines in North America, RTB has proven to be an aggressive and destructive pest of Pinus tabuliformis, China’s most widely planted pine species. The bionomics and occurrence, distribution, response to host volatiles, and host preference of this pine beetle in China are compared with what is known of the beetle in its native range in North America. Factors likely contributing to D. valens success in China and control of the beetle outbreak are discussed. (−)-β-pinene was shown to be the most attractive host volatile for D. valens from the Sierra Nevada of California, whereas 3-(+)-carene is the most attractive host volatile for beetles in China. Monocultures of Pinus tabuliformis, several consecutive years of drought conditions and warm winters have apparently factored D. valens invasion and establishment in China.     

Transformation and regeneration of loblolly pine: shoot apex inoculation with Agrobacterium

Loblolly pine (Pinus taeda L.) is the mostimportant tree species in US commerce and has much to gain through geneticengineering. This species can be transformed using particle bombardment andAgrobacterium; however, the regeneration of plants fromtransgenic tissues has been difficult and the recovery of transgenic plants hasbeen rare. A shoot-based and genotype-independent transformation methodemploying Agrobacterium tumefaciens was used to facilitaterecovery of plants and permit the transformation of elite germplasm. Shootsfrom4–6 week old seedlings and adventitious shoots from culture wereinoculated with A. tumefaciens EHA101 (pGUS3), or EHA105(pSSLa.3), subjected to selection and regenerated. Shoots that survivedexhibited expression of the uidA gene (GUS) in a patterncharacteristic of the either the CaMV35S promoter (pGUS3), or the larch RbcSpromoter (pSSLa.3) transferred. Recovered plants were screened using PCRamplification. Southern DNA analyses and amplification of the T-DNA borderjunction confirmed genomic integration of both transferreduidA and nptII genes. In this proofofconcept study, the overall recovery of P. taeda shoots wasfair (10–20%), while recovery of intact rooted plants was poor (>1%)due to difficulty in rooting. Recovery of intact rooted plants from inoculatedshoots of P. eldarica and P. radiatawas more efficient (10–30%). The addition of a shoot multiplication stepand effective rooting protocols will improve the efficiency of this genotypeindependent transformation method in P. taeda, and inotherPinus spp.     

Short-term effects of thinning and liming on forest soils of pitch pine and Japanese larch plantations in central Korea

The influences of thinning (50% of standing density) and liming (Ca+Mg, 2 Mg ha⁻¹) on soil chemical properties were investigated for 2 years (2001, 2002) in 40-year-old pitch pine (Pinus rigida Mill.) and 44-year-old Japanese larch (Larix leptolepis Gord.) plantations established on similar soils. In general, soil properties varied significantly among plantations and treatments. For both plantations, thinning significantly increased soil organic C (SOC) concentrations whereas there were no significant changes in soil pH and Ca and Mg concentrations. In addition, thinning increased total soil N and Na concentrations for the pitch pine plantation and available P concentration for the Japanese larch plantation in the second year after the treatment. Liming did not affect soil chemical characteristics for the pitch pine plantation except for Na concentration. However, for the Japanese larch plantation, liming significantly increased soil pH and K, Ca and Mg concentrations and decreased SOC and total soil N concentrations. For both plantations, soil Al concentration did not change after thinning and liming and decreased exponentially with increased pH values. The increases in SOC and total soil N concentrations after thinning were possibly due to increases in decomposition of organic matter and root death. Although differences were not statistically significant, soil available P concentration tended to increase at early stages of liming for both plantations. These results suggested that thinning and liming seemed to regulate soil chemical properties for pitch pine and Japanese larch plantations established on similar soils.     

Importation of Exotic Ticks into the United Kingdom via the International Trade in Reptiles

Due to the increased trade in exotic reptiles, many of which are infested with ticks of various genera, there is an increased risk of exotic ticks and pathogens being introduced and potentially becoming established in new geographical areas. Despite the number and variety of tick species collected from reptiles, their role in the maintenance of pathogens and transmission to humans has not been fully investigated for all species. The potential public health risks to the United Kingdom have been examined through a preliminary study involving the collection and identification of exotic tick species imported via the reptile trade. Reptiles imported into Heathrow Airport, London (July 2003–October 2004) were carefully examined for ectoparasites. Five species of tick were collected: Aponomma exornatum, Ap. latum, Amblyomma rotundatum, Am. dissimile and Am. nuttalli. This is the first report of Am. dissimile identified from an interception at Heathrow airport. The potential for establishment of exotic ticks in the UK and the public health risks are discussed.     

Non-morphogenic metabolism during shoot induction in radiata pine cotyledon explants

Summary The effects of excision, light and cytokinin (N⁶-benzyladenine) on¹⁴C-acetate metabolism in cotyledons ofPinus radiata (D. Don) were determined.¹⁴CO₂ was released and the distribution of radioactivity into lipids, sugars, organic acids and amino acids was determined. While light and cytokinin generally caused some increase in metabolism, the effect of excision, i.e., wounding, was most pronounced. Specific metabolites examined (citrate, malate, succinate, alanine, aspartate, glutamate and glutamine) were at least 50% greater in¹⁴C-labeling in excised cotyledons as compared to intact seedlings. This enhancement of wound metabolism would mask possible morphogenically-related changes occurring at that time. This research was supported by the Natural Sciences and Engineering Research Council of Canada Grant A-6467 to T.A. Thorpe.     

A biolistic approach for the transfer and expression of a gusA. reporter gene in embryogenic cultures of Pinus radiata

Summary The biolistic® particle delivery system was used for the delivery of DNA into embryogenic tissue culture cells of Pinus radiata D. Don. Several experiments with varying parameters were performed to increase the delivery efficiency. Six different controlling elements were cloned upstream of the ß-glucuronidase coding sequence (gusA reporter gene) and transient expression of the gusA reporter gene was compared three days after bombardment. The results clearly indicate a decrease in transient expression as follows: pEmu-derivatives with the ocs-enhancer-element > 2x CaMV 35S (with Kozak consensus-sequence) > 2x CaMV 35S (without Kozak consensus sequence) > CaMV 35S (with Kozak consensus-sequence) > CaMV 35S (without Kozak consensus sequence). Time course experiments monitoring gusA expression showed a significant decrease in the number of blue spots 10–14 days after bombardment. A few blue clumps however, were still detected 35 days after shooting. Embryo initials expressing the gusA gene in all cells were also detected. The results suggest that it will be possible to develop a reliable biolistic protocol for stable integration of genes into Pinus radiata embryogenic cultures which are capable of plant regeneration.Abbreviations ccc covalently closed circular DNA - lin linearised DNA - E restriction enzyme Eco RI - Sph restriction enzyme SpH I - 2,4-D 2,4-dichlorophenoxyacetic acid - BAP 6-benzylaminopurine     

Testing for linkage disequilibrium in the New Zealand radiata pine breeding population

Linkage analysis is commonly used to find marker-trait associations within the full-sib families of forest tree and other species. Study of marker-trait associations at the population level is termed linkage-disequilibrium (LD) mapping. A female-tester design comprising 200 full-sib families generated by crossing 40 pollen parents with five female parents was used to assess the relationship between the marker-allele frequency classes obtained from parental genotypes at SSR marker loci and the full-sib family performance (average predicted breeding value of two parents) in radiata pine (Pinus radiata D. Don). For alleles (at a marker locus) that showed significant association, the copy number of that allele in the parents was significantly correlated, either positively or negatively, with the full-sib family performance for various economic traits. Regression of parental breeding value on its genotype at marker loci revealed that most of the markers that showed significant association with full-sib family performance were not significantly associated with the parental breeding values. This suggests that over-representation of the female parents in our sample of 200 full-sib families could have biased the process of detecting marker-trait associations. The evidence for the existence of marker-trait LD in the population studied is rather weak and would require further testing. The exact test for genotypic disequilibrium between pairs of linked or unlinked marker loci revealed non-significant LD. Observed genotypic frequencies at several marker loci were significantly different from the expected Hardy-Weinberg equilibrium. The possibilities of utilising marker-trait associations for early selection, among-family selection and selecting parents for the next generation of breeding are also discussed.     

Successful inoculation of mature pine with Tricholoma matsutake

Our finding demonstrates, for the first time, that the roots of mature pine trees can be successfully inoculated with a symbiotic ectomycorrhizal fungus, the valuable matsutake mushroom. Long root segments (ca. 5–10 mm in diameter, ca. 50 cm in length) of 50-year-old Pinus densiflora trees were excavated, washed, auxin-treated (2–5 mg indole butyric acid, IBA, per root) and incubated in moist Spagnum moss. Twelve months later, short roots were regenerated, of which approximately 90% were free of mycorrhizae. Mycorrhiza-free short roots were inoculated with mycelial pieces of Tricholoma matsutake and incubated further in a sterilized substrate. Four-and-a-half months later, roots putatively colonized by Matsutake were sampled near the inoculation points. A T. matsutake-specific ITS-rDNA fragment was amplified by nested PCR from approximately 80% of the root samples analyzed, whereas approximately 66% of the root samples processed for staining with Chlorazol black E displayed characteristic T. matsutake Hartig net structures. These results confirm the symbiotic infection of mature P. densiflora roots by matsutake.