Needle Loss Research Articles

Lophodermium needle cast, insect defoliation and growth responses of young Scots pines in Estonia

SummaryUsing a retrospective approach, based on historical needle cast disease and insect pest records, data series of needle losses (reconstructed by the use of the needle trace method), tree growth parameters and meteorological data were studied to determine the impact of the appropriate pointer (epidemic or calamity) years on the annual radial and height increment of 46 sample trees in six Scots pine (Pinus sylvestris) stands in Estonia from 1887 to 2006. First, the needle cast epidemics during the last 120 years were retrospectively determined, with resulting 4.6 epidemics per decade as a mean frequency. If the sum of precipitation from May to August reached 300 mm (the mean of 12 epidemic years studied: 361 ± 15 mm), an epidemic of needle cast caused byLophodermium seditiosummight follow the next year in young plantations. For insect defoliators, similarly clear triggering threshold values of precipitation or temperature could not be determined, although dry and warm summers and mild winters supported the calamities. We separately detected that both larger needle losses and growth reductions in trees related to Lophodermium needle cast epidemic years lasted until the same age of pines, 22–24 years, but for insect pest (diprinoid sawflies) calamity years the growth reduction lasted longer. The relevance of these findings for the prediction of Lophodermium needle cast epidemics is briefly discussed.

The impact of pine beetle infestation on snow accumulation and melt in the headwaters of the Colorado River

ABSTRACTThe mountain pine beetle is killing many trees in Colorado's high‐elevation forests. The thinned canopies found in dead tree stands should intercept less snow and transmit more radiation than canopies in living forests, altering snow accumulation and melt processes. We compare snow, forest, and meteorological properties beneath living and pine beetle‐killed tree stands. Eight pairs of living and dead tree stands were monitored over two years along the headwaters of the Colorado River. During year one, all eight dead stands were in the red phase of tree death — the trees still retained needles. Snow accumulation was the same under living and red phase stands, but snow melt was more rapid in red phase stands. As a result, the snowpack was depleted one week earlier in the red phase stands. Canopy shortwave transmission was not higher in red phase stands. We hypothesize that the faster melt and earlier depletion in red phase stands was caused by accelerated needle loss which lowers the albedo of the snow surface. By year two, many of the dead trees had progressed to the needle‐less grey phase of tree death. Snow accumulation in grey phase stands was 15% higher than in paired living stands. Snow in grey phase stands melted more rapidly than in living stands, likely as a result of increased canopy shortwave transmission. We combine our results with those from previous studies to develop a conceptual model that describes how beetle infestation affects snow accumulation and melt in the different stages of mortality. Copyright © 2011 John Wiley & Sons, Ltd.

Endogenous and exogenous ethylene induces needle abscission and cellulase activity in post-harvest balsam fir (Abies balsamea L.)

Post-harvest needle loss is a major problem for balsam fir and other Christmas tree species. Recent evi- dence has implicated ethylene as a signal responsible for post-harvest needle abscission, but enzymological changes remain unknown. The objective of this study was to identify and quantify cellulase activity associated with endogenous and exogenous ethylene-induced abscission. An experiment was designed with three treatments (control, endogenous ethylene, or exogenous ethylene) with five replicates. Key response variables include needle retention duration, xylem pressure potential, ethylene evolution rate, and cellulase activity. Two complimentary methods were used to assess cellulase activity: a cellulose plate digestion and zymog- raphy. The results confirm ethylene as a signal for post-harvest abscission and identify ethylene-induced cel- lulase. Ethylene evolution was typically between 15 and 16 l Lg -1 h -1 , but there was no difference among the three treatments. However, exogenous ethylene significantly decreased needle retention by 60% and resulted in a sixfold decrease in xylem pressure potential. In addition, cellulase activity increased by 8- and 12-fold in endogenous and exogenous ethylene-induced abscission, respectively, compared to the control. Identification of ethylene-induced cellulase activity has increased our understanding of the post-harvest needle abscission process and confirms ethyl- ene's role as a signal molecule.

Shoot Blight Caused by Sirococcus tsugae on Eastern Hemlock (Tsuga canadensis) in Georgia.

Eastern hemlock (Tsuga canadensis) is an ecologically and economically important conifer from the north-central United States to the east coast of North America to the southern Appalachian Mountains. In early spring 2010, blighted shoot tips of eastern hemlock were observed at widely separated locations in the Chattahoochee National Forest in north Georgia. Damage did not appear to be directly related to hemlock woolly adelgid (Adelges tsugae) activity, which was sporadic or absent in some areas where symptoms were observed. A preliminary survey in March 2010 revealed that incidence of blighted shoots on individual trees varied, but was as high as 70%. Stems of shoots produced the previous year were frequently necrotic, had lost needles, and bore pycnidia with hyaline, two-celled conidia consistent with those of Sirococcus tsugae (2,3). Later in the spring and summer, shoots of the current year's growth became blighted, with sporulation of S. tsugae also on dead and dying needles. While S. tsugae previously has been reported on T. heterophylla, T. mertensiana, Cedrus atlantica, and C. deodara in western North America, it has only recently been reported on eastern hemlock (1), and its ability to induce shoot blight has not been proven. Pure cultures (2,3) were obtained on streptomycin-amended potato dextrose agar (PDA) and their identity was confirmed by species-specific PCR primers (4). Nuclear rDNA internal transcribed spacer sequence (554 nucleotides) also was obtained for isolate 10-05 and deposited in GenBank (Accession No. HQ256769). This sequence was found to be identical to sequences previously deposited for S. tsugae isolates. Isolate 10-05 and a second isolate (10-06) were used to inoculate potted 2-year-old eastern hemlock seedlings in a growth chamber at 20°C with a 16-h photoperiod. Conidia were collected by flooding 1-month-old colonies on PDA with sterile water. Expanding shoots on one branch of each seedling were wounded using scissors to cut the tips off needles and stems, while another branch remained nonwounded. Ten seedlings per isolate were inoculated by spraying to runoff with a suspension of 5 × 106 conidia ml-1 in sterile water, and five similarly treated control seedlings were sprayed with sterile water. Seedlings were covered with plastic bags to maintain high humidity for 4 days. Germination of conidia of each isolate incubated on water agar in this growth chamber was >80% after 24 h. Symptoms were evaluated and reisolation was attempted on streptomycin-amended PDA 2 months after inoculation. Symptoms of seedlings inoculated with either isolate included chlorotic and necrotic needle spots, browning of cut edges of needles, browning and death of needle tips and entire needles, death of stem tips with retention of dead needles, and needle loss. Symptoms of control seedlings were limited to slight browning of cut edges of needles. The fungus was reisolated from wounded shoots of 17 of 20 inoculated seedlings and nonwounded shoots of 5 of 20 inoculated seedlings and was not cultured from control seedlings. To our knowledge, this is the first report of S. tsugae in Georgia and also the first demonstration of its ability to produce symptoms that have been attributed to it on any tree species.

Ethylene Exposure Duration Affects Postharvest Needle Abscission in Balsam Fir (Abies balsamea L.)

Needle loss after harvest is a major problem for Atlantic Canada's Christmas tree and greenery industry. Ethylene is a signal for abscission in balsam fir, but preliminary studies have suggested that the role of ethylene may be influenced by length of exposure. Short-term and long-term ethylene exposure experiments were conducted. Branches were exposed to ethylene for 24 h (short-term) or continuously (long-term) at concentrations of 0 to 1000 ppm. The response variables measured were needle retention duration (NRD), average water use (AWU), and xylem pressure potential (XPP). Short-term exposure to any concentration of ethylene delayed needle abscission by 30 to 40 days. In contrast, long-term exposure to all concentrations of ethylene accelerated abscission, most evident by a 21-day decrease in NRD at 1000 ppm ethylene. There was a 60% decrease in NRD, 160% decrease (more negative) in XPP, and 80% increase in AWU as a result of long-term exposure to ethylene. Overall, our results demonstrate an opposite effect of short-term and long-term ethylene exposure, which suggests that short-term exposure to ethylene might help to precondition balsam fir and delay needle abscission during postharvest handling.

Ground-living spiders (Araneae) at polluted sites in the Subarctic

Spiders were studied around the Pechenganikel smelter combine, Kola Peninsula, north-western Rus- sia. The average spider density was 6-fold greater and the density of Linyphiidae specimens 11.5-fold higher at slightly polluted sites, compared with heavily polluted sites. Altogether, 18 species from 10 families were found at heavily polluted sites, the theridiid Robertus scoticus clearly dominating (23.3 % of identifiable specimens), also Neon reticulatus (9.6 %), Thanatus formicinus (9.6 %) and Xysticus audax (8.2 %) were abundant. The most numerous among 58 species found at slightly polluted sites were Tapinocyba pallens (18.5 %), Robertus scoticus (13.7 %), Maso sundevalli (9.5 %) and Alopecosa aculeata (8.2 %). The family Linyphiidae dominated at slightly polluted sites, 64 % of species and 60 % of individuals; compared with heavily polluted sites, 23 % and 38 % respectively. In the late 1980's, reports of heavy pollution loads from the Russian smelters in the Kola Peninsula and their possible effect on needle losses among pine in northern Finland prompted active studies on effects of pollution on forest ecosystems in northern Fin- land, Russia and Norway (see KOZLOV et al. 1993, TIKKANEN & NIEMELA 1995). Spiders, like some other predatory arthropod groups, have been observed at heavily polluted sites near smelters in northern Europe (BENGTSSON & RUDGREN 1984, KONEVA 1993, KOPONEN & NIEMELA 1994, KOPONEN & KONEVA 2006). Gen- erally, markedly high concentrations of heavy metals have been found in spiders near pollution sources (BENGTSSON & RUNDGREN 1984, KOPONEN & NIEMELA 1995, MAELFAIT & HENDRICKX 1998), and spiders have often been used as indicators in monitoring the effects of pollution (e.g. CLAUSEN 1986). In the present paper, information will be given on spider assemblages near the Pechenganikel smelter complex, in the subarctic Kola Peninsula, NW Rus- sia.

Classification of Defoliated Trees Using Tree-Level Airborne Laser Scanning Data Combined with Aerial Images

Climate change and rising temperatures have been observed to be related to the increase of forest insect damage in the boreal zone. The common pine sawfly (Diprion pini L.) (Hymenoptera, Diprionidae) is regarded as a significant threat to boreal pine forests. Defoliation by D. pini can cause severe growth loss and tree mortality in Scots pine (Pinus sylvestris L.) (Pinaceae). In this study, logistic LASSO regression, Random Forest (RF) and Most Similar Neighbor method (MSN) were investigated for predicting the defoliation level of individual Scots pines using the features derived from airborne laser scanning (ALS) data and aerial images. Classification accuracies from 83.7% (kappa 0.67) to 88.1% (kappa 0.76) were obtained depending on the method. The most accurate result was produced using RF with a combination of data from the two sensors, while the accuracies when using ALS and image features separately were 80.7% and 87.4%, respectively. Evidently, the combination of ALS and aerial images in detecting needle losses is capable of providing satisfactory estimates for individual trees.

Drought-induced growth decline of Aleppo and maritime pine forests in south-eastern Spain.

Climate warming may enhance the negative effects of droughts on radial growth in areas with severe water deficit, such as Mediterranean mountains under semi-arid conditions. The impacts of drought on growth decline of Mediterranean pines have not been evaluated considering species with different vulnerability and areas with contrasting climates. Dendrochronological methods were used to assess the responses of basal area increment to drought in Pinus pinaster and P. halepensis plantations. We compared growth trends of trees with different defoliation degree in two sites in south-eastern Spain (Sierra de los Filabres and Sierra de Baza) with contrasting climatic conditions. In the more xeric area (Filabres) both pine species showed a sharp growth reduction in response to extreme droughts such as those observed in 1994-1995, 1999 and 2005. The radial growth of both species was enhanced by May and June precipitation of the year of tree-ring formation. P. pinaster showed higher defoliation in the xeric area (Filabres) than in the more mesic area (Baza) but needle loss was not linked to an abrupt growth reduction. Contrastingly, divergent radial growth patterns between trees showing high and low defoliation degrees were found for P. halepensis in the more xeric area, where a negative relationship between recent basal area increment and defoliation was found. Pine plantations in Mediterranean mountains under semi-arid conditions are highly vulnerable to warming-induced droughts. Such marginal stands constitute valuable monitoring systems to assess the negative impacts of drought on tree growth, and to test if management strategies as thinning can mitigate the negative impacts of climate warming on similar drought-stressed forests.

First Report of Phytophthora ramorum Infecting California Red Fir in California.

In May 2005, branches originating from five separate whorls below the terminal on a single California red fir (Abies magnifica) in a mixed grand fir (Abies grandis) and Douglas-fir (Pseudotsuga menziesii) Christmas tree plantation near Los Gatos, CA displayed wilting and dieback of new shoot growth. Brown dieback, delineated by needle loss, extended 6 to 8 cm into 1-year-old and sometimes 2-year-old growth. The ~7-year-old, 1-m tall tree was located near the edge of the plantation, beneath an overstory of California bay laurel (Umbellularia californica) trees that were infected with Phytophthora ramorum. Isolations from dieback margins onto corn meal agar amended with ampicillin, rifamycin, and pimaricin (CARP) yielded hyphae and large, dark brown chlamydospores that were morphologically consistent with P. ramorum (1). Microsatellite analysis confirmed that isolates were of the NA1 lineage of P. ramorum. Isolates were deposited in the Washington State University Puyallup Phytophthora Master Collection. Dormant bareroot California red fir seedlings were obtained from the USDA Forest Service Placerville Nursery (Camino, CA) in February 2006 and planted in SC-10 super cell cones (Stuewe & Sons, Inc., Tangent, OR) in a standard greenhouse potting mix. Seedlings (average height 11 cm) were then forced to initiate bud break and new shoot elongation (0.5 to 1.5 cm) in a greenhouse at 21°C. Eight unwounded seedlings were inoculated with a zoospore suspension (4.185 × 105 zoospores/ml of sterile water) produced from 3- to 4-week-old V8 juice agar cultures of isolate WSU#106-0021 using an artist's airbrush powered by Badger Propel canned propellant. Eight control seedlings were sprayed with water alone. Seedlings were placed in plastic tubs with ~2.5 cm of warm water in the bottom to provide humidity. A plastic bag supported by a wire frame was used to cover each tub. Tubs were placed in a biocontainment unit at 15 to 16°C under 24 h of fluorescent light. The plastic was removed after 5 days and seedlings were left under the same conditions. Seven days after inoculation, 25 to 100% (average 68%) of the new shoots on each of the eight inoculated seedlings were wilted and 100% of these seedlings exhibited dark brown dieback into the 1-year-old stems (range of 1.0 to 2.3 cm, average 1.6 cm). Tissues from shoots and dieback edges were plated onto CARP media. All of these attempts resulted in successful isolation of P. ramorum, and cultures exhibited the same hyphal morphology and chlamydospore characteristics when compared with the isolate tested. Control plants did not develop symptoms. This trial completes Koch's postulates to establish California red fir as a host of Phytophthora ramorum. To our knowledge, this site contains the only reported infection of California red fir by P. ramorum. The potential for infection within its native range is unknown. Reference: (1) S. Werres et al. Mycol. Res. 105:1155, 2001.

Assessing differences in tree and stand structure following beetle infestation using lidar data

The current mountain pine beetle (Dendroctonus ponderosae Hopkins) infestation in British Columbia is the largest in recorded history and has caused unprecedented damage to the lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) forests of the interior of the province. During the early years after attack, changes to overall crown structure are relatively minor due to low needle loss; within several years, however, needle loss can be substantial, even at the stand level. Needle loss can affect snow hydrology due to the role of the canopy in interception and accumulation and its impacts on radiation transmission, wind speed, and the overall snowmelt energy balance. In addition, the infestation is impacting other forest attributes such as wildlife habitat, forest fire risk and behaviour, and biogeochemistry. In this paper we investigate variations in light detection and ranging (lidar) return hit densities and distributions, analyzed with high spatial resolution digital camera imagery, in response to changes in forest cover and structure due to beetle infestation at both the individual tree level and the stand level. Results indicate that the density of lidar returns from tree crowns is impacted by the later health status of the tree, with a larger number of returns from green and early attack phases and a significantly smaller number of returns from grey-attack crowns. At the stand level, there are a number of significant relationships between plot-level indicators of infestation and lidar-derived structural metrics, in particular with vegetation cover (r2 = 0.76, p < 0.001). The total number and vertical distribution of returns from vegetation in green, red-attacked, and grey-attacked pine stands were distinct. We conclude that the potential to combine the structure information derived from lidar technology with assessment of heath status from aerial imagery provides unique quantitative data that may be used to map lodgepole pine stands according to structural attributes relevant to both silviculturalists and hydrologists.

Compression Properties of Polyester Needlepunched Fabric

In the present paper, a study of the effects of fabric weight, fiber cross-sectional shapes (round, hollow and trilobal) and presence of reinforcing material on the compression properties (initial thickness, percentage compression, percentage thickness loss and percentage compression resilience) of polyester needle punched industrial nonwoven fabrics is presented. It was found that for fabrics with no reinforcing material, the initial thickness, compression, and thickness loss were higher than fabrics with reinforcing material, irrespective offiber cross-section. Compression resilience data showed the reverse trend. Initial thickness for trilobal cross-sectional fabric sample was highest followed by round and hollow cross-sectioned polyester needle punched fabrics. The polyester fabric made from hollow cross-sectioned fibers showed the least percentage compression at every level of fabric weights. The trilobal cross-sectioned polyester fabric sample showed higher thickness loss followed by round and hollow cross-sectioned polyester fabric samples respectively. The hollow cross-sectioned polyester fabric samples showed maximum compression resilience followed by round and trilobal cross-sectioned polyester samples irrespective of fabric weights. The initial thickness increases, but percentage compression, thickness loss and compression resilience decreases with the increase in fabric weight irrespective of fiber cross-sectional shapes.

Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model

Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce ( Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6–12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO 2 concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century.

Snow ablation energy balance in a dead forest stand

AbstractForest disturbance has a significant impact on hydrology due to its effect on the forest canopy, which is important for precipitation interception, transpiration, site micrometeorology, and snow accumulation and ablation. This study examines the impact of mountain pine beetle infestation and subsequent forest death on snow ablation. Dead stands experience needle loss and canopy reduction due mainly to the loss of small branches and stems, which has a subsequent impact on micrometeorological conditions. Ablation is driven largely by incoming short‐wave radiation, which in dead stands is greater than in alive stands, but does not reach that available in clearcuts. Long‐wave radiation emission in dead stands is lower than that in alive stands, reducing its contribution to snowpack warming and ablation. Turbulent flux contributions to snow ablation are limited in forest stands relative to clearcuts, although they are slightly greater in dead than alive stands due to the more open forest structure. Additional studies are required to refine the basic energy balance model and incorporate all processes affecting the snow ablation energy balance. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Growth response of young Scots pines to needle loss assessed from productive foliage

Growth response of young Scots pines to needle loss assessed from productive foliage The amount of productive foliage was assessed with the help of the relative significance of each annual needle set in their contribution to the growth of young Scots pines (Pinus sylvestris). The number of needles in the subsequent needle sets was studied retrospectively in twelve-year-old stand, and the worst needle loss years were detected. The growth rate of trees was compared with the number of needles in the annual needle sets and with the loss of needles from the assessed productive foliage. Needles in the 4th and older needle sets remaining in the trees were interpreted as useless or less important if their amount did not correlate with the growth. The second and third needle sets supported both radial and height growth. Most variation in the needle loss during 1999-2002, caused mainly by summer drought and by fungal needle cast due to Lophodermium seditiosum, occurred in the third annual needle set. Decrease in both radial and height increments in relation to the needle loss were apparent in the total material for 1997-2004, but needle loss reduced the annual growth significantly only in two-three years inside that period.

Genetic resistance in Pinus radiata to defoliation by the pine aphid Essigella californica

Summary The Monterey pine aphid, Essigella californica, has been associated with extensive defoliation and growth losses in radiata pine plantations in south-eastern Australia since it was first detected in 1998. HVP Plantations (HVPP) observed variation in the level of defoliation between clones in clonal seed orchards and archives, and initiated a program of assessment of progeny trials. Between 2001 and 2005, defoliation was assessed in a provenance trial, a subset of clones within a seed orchard, and 18 progeny trials (some repeatedly). Needle retention in upper crowns was scored on a scale of 1–10, rather than needle loss, because this ensured higher scores equated to the desirable state of the assessed trait. There were significant differences in the extent of retained foliage between populations, and between subpopulations within populations. The inland northern (Coastways Ranch) sub-population of Año Nuevo population had the highest level of retained foliage in the upper crown (mean score of 8.3), and the northern (Pico Creek, Haarst Ranch) sub-population of the Cambrian population had the least retained foliage (5.0). Estimates of heritability from progeny trials ranged from 0 to 0.9, and averaged about 0.5 in trials where there was a significant family (maternal) effect. Cross-site analysis using a family model resulted in an overall heritability of 0.4. Genetic correlations between assessments across two trials in 2004 and those in 2001 and 2003 were high, suggesting that defoliation due to aphids is consistent across years and can be considered to be the same trait. In addition to the observed differences between provenances and families, there were significant differences between clones, and average levels of retained foliage among clones ranged from 1.9 to 9.4. HVPP has used this information to develop an aphid-resistant breed of radiata pine which has been deployed on an increasing scale since 2005 into the most susceptible areas of its Victorian estate.

Mycosphaerella dearnessii and Mycosphaerella pini

<i>Mycosphaerella dearnessii</i> and <i>Mycosphaerella pini</i>

The decline of Greek fir (Abies cephalonica Loudon): Relationships with root condition

The decline of Greek fir (Abies cephalonica Loudon) has been reported throughout Greece during the last three decades. The symptoms include crown dieback, needle discoloration and loss, death of twigs, branches or whole tree death. A number of causes for the fir decline have been proposed such as drought, climatic change, air pollution and pathogens or insects. Our studies have focused on the relationship between fir decline symptoms and root growth and condition. The crown and root condition of fir trees, at different stages of decline, were assessed and the results showed that root condition was related to needle loss and crown discoloration. Declining trees were characterized by a decreased portion of fine root biomass. No significant differences in total root length and number of roots for each root order were found. In conclusion, our studies showed that the crown condition of Greek firs is reflected on root condition.

Complications of laparoscopic pyeloplasty

With the development of new video-endoscopic techniques like endopyelotomy, laparoscopy and retroperitoneoscopy the treatment of UPJO has become less invasive. The complications and learning curve of laparoscopic pyeloplasty are presented together with recommendations for adequate management. Based on the personal experience with 189 cases of retroperitoneoscopic pyeloplasty, a literature review (PubMed) was performed focussing on complication and success rates of the procedure. Intraoperative incidents were analysed using the Satava-classification, postoperative complications according to the Clavien-classification. The meta-analysis focussed on the experience of the 3 largest and 2 smaller series representing a cohort of 601 patients. Intraoperative incidents ranged from 2.0 to 2.3% in large series, mostly without consequences for the patient including ligation of lower pole artery, loss of needle, hyperkapnia, cutting of DJ-stent, colonic injury, and port site bleeding. The conversion rate was mainly due to inability to access UPJ or to accomplish the anastomosis ranging between 0.5 and 5.5%. Postoperative complications occured between 12.9 and 15.8% in large series. A total of 5.4-10% represented Grade III-complications, such as urine leakage, haematoma, colonic lesion, and stone formation. Recurrent UPJ-stenosis requiring reintervention was seen in 3.5-4.8%. In all three large series, complications were part of the learning curve. Laparoscopic pyeloplasty has been proven safe and effective with comparable results to open surgery. The experience of pioneering centres with incidence and management of complications will be used by next generations of laparoscopic urologic surgeons to shorten their learning curve.

Assessing the role of bark‐ and wood‐boring insects in the decline of Scots pine (Pinus sylvestris) in the Swiss Rhone valley

Abstract 1. In several dry inner Alpine valleys higher mortality levels of pine have been observed in recent years. This paper evaluates the role of xylophagous insects in the current pine decline and the influence of climate change on the infestation dynamics.2. More than 200 trees of different levels of crown transparency (needle loss) were felled between 2001 and 2005 and sections of them incubated in insect emergence traps. Colonisation densities were related to the transparency level of each host tree at the time of attack.3. Trees with more than 80% needle loss were colonised most frequently, but the breeding density was highest in trees with 65–80% needle loss.4. The scolytine Ips acuminatus and the buprestid Phaenops cyanea colonised trees with 30–90% needle loss in high densities. The bark beetle Tomicus minor was less aggressive, preferring trees with 60–85% needle loss. The hymenopteran Sirex noctilio and the cerambycid Acanthocinus aedilis were restricted to greatly weakened trees with 50–85% needle loss. Most species colonised trees that had experienced a decline in vigour, that is an increase in crown transparency shortly before attack.5. The infestation dynamics of P. cyanea covaried with the drought index as well as with temperature.6. Increased temperatures not only trigger a drought stress rendering the host trees susceptible to insect attack, but also accelerate insect development. As more frequent drought periods are likely as a result of climate change, even trees only slightly or temporarily weakened will be more subject to attack by aggressive species such as I. acuminatus and P. cyanea.

The uncoupling of secondary growth, cone and litter production by intradecadal climatic variability in a mediterranean scots pine forest

The relationships between climate variability and canopy dynamics (monthly litter production), chemical composition of the litter, secondary growth and female-cone production were studied in an old growth Scots pine ( Pinus sylvestris) forest over the 1993–2003 period. The forest was located at a Mediterranean mountain site (Valsaín, Segovia, central Spain). The temporally explicit relationships between the mentioned variables were explored by chronological cluster of their time series. Mean air temperature significantly influenced litter production and its seasonal and intradecadal patterns. Seasonal patterns of litter N and P content were negatively correlated with litter production, exhibiting minima of 5.3 g kg −1 (N) and 0.5 g kg −1 (P) by the end of the summer and maxima of 15 g kg −1 (N) and 1.2 g kg −1 (P) during winter; these results are interpreted as retranslocation before needle shedding in summer and loss of green needles in winter respectively. In general the driest and hottest years (1994 and 1995) were associated with significantly decreased secondary growth in the next year, an increased cone production, and an increased nutrient loss due to the combined effect of an increased litter production and an increased nutrient concentration of the litter. Climatic changes during the early stages of cone formation that take place during the spring led to alterations in masting and in the tri-annual process of cone production. Since each parameter studied was differentially affected by climatic variability, the overall effect of the short-term climatic changes experienced by the Scots pine forest studied was an uncoupling of litter production, secondary growth, and reproduction.