Young Spruce Research Articles

The effect of spruce stand thinning on biological activity in soil

The effect of thinning of young spruce stands by 500 trees/ha on biological activity in the soil profile was studied in the mountainous area of the Moravian-Silesian Beskids. The biological activity of soil was determined under optimal laboratory conditions by tests of soil respiration, catalase activity and intensity of cellulose decomposition. No statistically significant differences were found between the individual biological tests when the two experimental stands were compared (P-level 0.05). All biological activities within each stand were correlated, and significant correlations were found between biological activities in the soil and ammonium nitrogen content.

Regrowth response of young black spruce (Picea mariana) trees to meristem removal and resource addition

Regrowth of an injured plant may exceed the growth of a noninjured plant (i.e., overcompensation) when (i) dormant meristems are available to replace injured meristems, (ii) the injury level is sufficient to release dormant meristems from apical dominance, and (iii) the supply of mineral nutrient and light is sufficient to support the outgrowth of previously dormant meristems. A field experiment was conducted with 5-year-old black spruce trees to determine whether these three conditions were met when 25%, 50%, or 75% of a tree's uppermost buds were removed. Subsequent shoot growth on treated and nontreated trees (0% meristem removal) was compared for each of two levels of resource supply (natural and enhanced). Enhanced levels of light and mineral nutrients were created by removing neighbouring plants within a 2-m radius of a target tree and adding 10 grams of N–P–K fertilizer per tree. After 5 and 17 months, shoot growth did not differ significantly among trees in the four meristem removal treatments (condition ii above), regardless of resource supply (condition iii above). The absence of overcompensation most likely reflects the relatively small supply of dormant meristems on treated trees (condition i above).Key words: apical meristem, black spruce, compensatory growth, injury.

Understory vegetation in northern Ontario jack pine and black spruce plantations: 20-year successional changes

The 20-year successional development of understory vegetation was investigated in jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) plantations in northern Ontario, in relation to stand species composition, species diversity, and the rate of change in stands of different post-disturbance ages. Detrended correspondence analysis (DCA) ordination of plantation stands using species composition data from 1978 and 1998 indicated variation among stands in directions and rates of change in species composition over time. Rank correlations of environmental variables with the DCA axes suggested a light–moisture gradient along the first axis, driven by soil texture and overstory species, and a gradient representing time since disturbance and stand development along the second axis. Although overall beta diversity among stands remained constant over time, some convergence was found among a smaller group of stands, and divergence was noted between spruce and pine stands. Species composition also became more highly correlated with environmental variables through time. From 1978 to 1998, species richness increased in young, dry pine stands; decreased in older, dry pine stands; and decreased in young spruce stands. The understory vegetation in stands on mesic sites was more diverse than that on dry, sandy sites at both times. The rate of change in understory species composition slowed with time after disturbance, indicating an increasing stability in micro en vi ron men tal conditions as the influence of harvesting disturbance became weaker with time.

Hat die Waldweide eine Zukunft? Ein interdisziplinäres Projekt in den Alpen | Is there a future for forest grazing? An interdisciplinary project in the Alps

Fifteen percent of the mountain forests in Switzerland are grazed by domestic animals. The forest laws of some alpine cantons prescribe a new regulation of controversial grazing rights. To evaluate the cost and benefit of forest grazing the Swiss Federal Institute for Snow and Avalanche Research (SLF)at Davos started an interdisciplinary project in May 2000 on the behaviour of cattle and the dynamics of forests on subalpine wood pastures. A first step describes the management of subalpine wood pastures. In order to determine herbage supply and the selection of specific plant species, vegetation maps were drawn up before and after grazing. Using a double indicator technique,which involved the daily collection of faeces and herbage spot samples, herbage intake and digestibility were analysed. Intake of tree parts was quantified by measuring the shoot lengths of young spruces, larches and rowans immediately before and after grazing. Collars equipped with GPS were used to study the cattle's spatial use of (sub-)alpine pastures. Long term effects on forest structure and wood quality were investigated using dendroecological techniques. Based on the results of these studies, it will be possible to ascertain basic conditions for a sustainable management of Alpine silvopastoral systems. Concluding, an outlook will be given on the possible future of forest grazing in the Swiss Alps and in other regions of Europe.

The effect of soil cultivation methods on rooting depth of young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees on wet mineral soils in Ireland

Summary The research reported in this article, carried out in the period 1995‐1997, was part of a large-scale project investigating the impact of soil cultivation/drainage practices upon water-table depth, rooting depth, root architecture and biomass production of young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees on surface water gley soils. On two sites in the mid-west of Ireland, a total of 207 trees, 5 and 7 years old, were excavated over a 2-year period, during which water-table depths were monitored. Results showed that neither mound drains nor mole drains had as great an effect on tree rooting depth as the presence of a planting mound. In the cultivation treatments that included planting on mounds, tree roots were mainly confined within the mounds, with the exception of the tree root systems in the mole-and-mound treatment on one of the sites, where the mean root depth of both the 5-year-old and 7-year-old trees reached almost 20 cm below the original soil level. Continued evaluation of these experiments is required to assess the long-term effectiveness of the different drainage and cultivation methods in increasing rooting depth and improving tree stability.

Growth change of young Picea sitchensis in response to deer browsing

Taking advantage of the introduction of the black-tailed deer to the Queen Charlotte Islands (British Columbia, Canada), we used dendrochronological analyses to understand the consequences of deer browsing on Sitka spruce growth. We compared shape, radial growth, height growth and age of young spruce in three sites. We identified two types of trees growing side by side: (1) stunted and heavily browsed spruce, smaller than the browsing limit and (2) escaped spruce that were taller than the browsing limit but still browsed in their lower part. The compact and heavily ramified shape in stunted spruce was the result of repeated and intense browsing. In escaped spruce this was also the case below the browsing limit ( 1.16 m±0.07 m), in sharp contrast with the normal shape that escaped spruce resumed above the browsing limit. We show that the release of browsing pressure, once the tree reaches the browsing limit, is characterised by an abrupt increase in radial growth. Before release, trees show a growth stagnation characterized by narrow rings (0.5 mm per year) and small annual height increments (<5 cm per year). After release, trees show a growth stabilisation characterised by wider rings (3 mm per year) and larger annual height increments (20 cm per year). We use this pattern to estimate frequency and age at release and their possible variation over time. Age differences between stunted and escaped spruce are highly significant and indicate that, despite of browsing, most if not all trees will ultimately reach the browsing limit and escape. Heavy deer pressure (30 deer per km 2) delays spruce sapling recruitment by about 8 years. This delay varies in relation to site quality and seems to have increased over time, suggesting an increase in browsing pressure.

Risk of attack by the bark beetle pityogenes chalcographus (L.) on living trees close to colonized felled spruce trees

The bark beetle Pityogenes chalcographus (L.) occasionally kills trees in young stands of Norway spruce Picea abies (L.) Karst. Suitable breeding material, e.g. piles of fresh logging waste, may potentially increase the risk of attacks on nearby stands. In southern Sweden, young spruce were cut and piled in spring at 31 stand edges of young spruce facing clear‐cuts. Pityogenes chalcographus attacks were recorded within stand edge plots near the piles during two summers after piling. Plots randomly located along 27 stand edges without piles were used as controls. The experiment was repeated in 3 yrs. All piles were colonized by P. chalcographus early in the first summer after piling. Plots with piles had five times more attacked standing trees, and > 40 times more entrance holes than controls. Almost all attacks occurred when the piles were being colonized. Of a total of 226 attacked trees only four were killed. In conclusion, the risk of P. chalcographus killing young healthy spruce trees close to piles of breeding material is low.

Health condition of young spruce stands growing in Poľana in different altitudes

This paper presents the first results of chlorophyll fluorescence measurements on assimilatory apparatus of Norway spruce. Three young spruce stands located in various altitudes (600, 1,050 and 1,250 m above sea level) were selected for the measurements. Chlorophyll fluorescence a was measured by a portable fluorimeter PEA. These measurements were performed on three needle year-classes. We found greater stand damage on the areas which are located in higher altitudes, but only at the end of growing season.

Chrysopids and Hemerobiids (Plannipenia) of young spruce forests in the eastern part of the Czech Republic

Chrysopids and Hemerobiids were studied using Malaise traps in young spruce forests in the eastern part of the Czech Republic. A total of 12 species were found. The most abundant species were eurytopic Chrysopa carnea, Chrysopa perla, Hemerobius humulinus and Hemerobius pini associated with conifers. The seasonal flight activity of these species is discussed.

Croissance juvénile comparée de deux générations successives de semis d'épinette noire issus de graines après feu en forêt boréale, Québec

The objective of this study was to compare juvenile (0–12 years) height growth pattern of dominant mature trees from two virgin black spruce (Picea mariana (Mill.) BSP) forests established during the 19th century (1870) to that of young dominant black spruce seedlings newly regenerated following a 1983 fire on the same sites. The pattern was reconstructed by measuring the distance between terminal bud scars on young seedlings, and by precise counting of growth rings by cross-dating from the collar, which was identified by anatomical features, for mature trees. New seedlings growth was significantly higher than that of mature trees. Seedlings were almost twice as high as mature trees after 12 years of juvenile growth. Assuming that mature trees were dominant during their juvenile growth phase, we put forward the hypothesis that juvenile height growth of mature trees would have been affected by the combined action of spruce budworm (Choristoneura fumiferana (Clem)) and colder climatic conditions than those presently observed. Also, young seedlings juvenile height growth may have been favored by nitrogen soil enrichment along with more favourable climatic conditions.

Is escaping deer browse just a matter of time in Picea sitchensis? A chemical and dendroecological approach

We combined chemical and dendroecological analyses to understand the mechanisms that are involved in escaping deer browse by young Sitka spruce (Picea sitchensis) exposed to browsing by Sitka black-tailed deer (Odocoileus hemionus sitchensis) on Haida Gwaii (British Columbia, Canada). We compared chemical defences (terpenes), nutritive compounds (nitrogen, non-structural constituents, cellulose, and lignin), as well as age and radial growth of two young spruce categories growing side by side: (1) stunted spruces that were heavily browsed, shorter than the browse line, and (2) escaped spruces that were taller than the browse line but still browsed below the browse line. Escaped and stunted spruces did not differ in terpene concentrations, or in nutritive compound contents, suggesting that they had similar palatability. Escaped spruces were older that stunted spruces. Stunted and escaped trees had similar slow growth when young, suggesting no difference in initial browsing between the two spruce categories. For escaped spruce, there was a dramatic increase in radial growth at about 12–13 years old, suggesting that the apex of the trees had escaped deer browse. Because the two categories of spruces were equally accessible and did not differ in chemical defences or in nutritive compounds, and because escaped spruces were older than stunted trees and had a similar slow radial growth in their first 12–13 years, we conclude that morphological differences between stunted and escaped browsed trees are due to age and that it is only a matter of time before spruce escape deer on Haida Gwaii.

Competitive Effects on Plantation White Spruce Saplings from Shrubs That Are Important Browse for Moose

Abstract Conifer planting is often accompanied by herbicide control of surrounding broadleaf, woody plants that may interfere with conifer growth, a process that releases conifers from competitive suppression. Because potential competitors often provide browse for wildlife, their removal may conflict with objectives in multiple-resource management. While some agencies, such as the USDA Forest Service (USFS), have greatly reduced herbicide use, many other timber producers still rely on chemicals to release conifers from competing vegetation. In northeastern Minnesota, where moose (Alces alces) are a highly valued resource, we studied impacts of broadleaf shrubs on 4- to 16-yr-old white spruce (Picea glauca) along with the extent of browsing by moose on these shrubs. Height, diameter, and current vertical growth increment of spruce were compared among four levels of presence (density strata) of shrubs immediately surrounding each sapling. Spruce grew as well or better in the low and medium density strata as in the no-shrub stratum. In the high density stratum, height and growth increment, particularly in 10- to 16-yr-old spruce, appeared reduced. Presence of shrubs seemed to reduce frost damage in young spruce. Moose browsing reduced height of most shrub species, suggesting that these animals provide a release effect on adjacent spruce. We recommend a release strategy that avoids reduction of shrubs beyond the level that assures normal growth in young spruce, so as both to minimize loss of browse for wildlife and avoid unnecessary silvicultural costs. FOR. SCI. 48(2):283–289.

Effect of soil drought on evapotranspiration of a young spruce forest

Daily courses of the actual transpiration of a forest stand were determined by an experimentally verified mathematical Soil – Vegetation – Atmosphere Transfer model. The results refer to the Norway spruce (Picea abies [L.] Karst.) monoculture situated in the highest locations of the Beskids Mts. Drought-free transpiration was estimated as a model simulation run for nonlimiting soil moisture exceeding the level of decreased availability of water. Drought-induced reduction in transpiration was quantified as a difference between actual transpiration and simulated transpiration for moist soil. The results led to conclusions that dry soil causes a significant reduction in actual evapotranspiration and its components in comparison with moist soil. Simultaneously, the effect of soil desiccation was compensated by extremely high evaporative demands of the atmosphere, so that the daily totals of evapotranspiration and its components remained sufficiently high. The high values of global radiation and saturation deficit in the air favourably influenced the water regime of the analysed forest stand in the dry period.

Temporary loss of antibiotic resistance by marked bacteria in the rhizosphere of spruce seedlings

Survival and persistence of two plant growth-promoting rhizobacteria strains in the rhizosphere of young spruce seedlings were evaluated in field plots and soil microcosms. Bacillus polymyxa strain Pw-2R and Pseudomonas fluorescens strain Sw5-RN are spontaneous antibiotic-resistant derivatives of the naturally occurring parental strains B. polymyxa Pw-2 and P. fluorescens Sw5, respectively. Resistance to 200 μg ml −1 rifamycin in strain Pw-2R, and to 100 μg ml −1 each of rifamycin and nalidixic acid in Sw5-RN, facilitated monitoring of these bacteria in rhizosphere samples. Strains Pw-2R and Sw5-RN were each inoculated into the rhizosphere of spruce seedlings in field plots as well as in intact soil core microcosms that were incubated under controlled environmental conditions. Bacterial survival data based on the abilities of Pw-2R and Sw5-RN to be re-isolated from rhizosphere samples, and by growing on agar containing antibiotics, were collected over a 2-year period as part of a larger study. The population sizes of both bacterial strains appeared to drop below detection limits by the beginning of the second year as they failed to grow on primary isolation media containing antibiotics. However, strains Pw-2R and Sw5-RN grew on isolation medium with antibiotics if they were first isolated on agar without antibiotics and then replica-plated onto agar media containing antibiotics. A similar temporary loss of antibiotic resistance has been observed with endophytic bacteria, but our results suggest such masking may be of much wider significance than previously thought. If it commonly occurs in rhizosphere colonizing bacteria as well as endophytes, significant underestimates of bacterial population sizes in similar environmental samples may result.

Temporary loss of antibiotic resistance by marked bacteria in the rhizosphere of spruce seedlings

Survival and persistence of two plant growth-promoting rhizobacteria strains in the rhizosphere of young spruce seedlings were evaluated in field plots and soil microcosms. Bacillus polymyxa strain Pw-2R and Pseudomonas fluorescens strain Sw5-RN are spontaneous antibiotic-resistant derivatives of the naturally occurring parental strains B. polymyxa Pw-2 and P. fluorescens Sw5, respectively. Resistance to 200 microg ml(-1) rifamycin in strain Pw-2R, and to 100 microg ml(-1) each of rifamycin and nalidixic acid in Sw5-RN, facilitated monitoring of these bacteria in rhizosphere samples. Strains Pw-2R and Sw5-RN were each inoculated into the rhizosphere of spruce seedlings in field plots as well as in intact soil core microcosms that were incubated under controlled environmental conditions. Bacterial survival data based on the abilities of Pw-2R and Sw5-RN to be re-isolated from rhizosphere samples, and by growing on agar containing antibiotics, were collected over a 2-year period as part of a larger study. The population sizes of both bacterial strains appeared to drop below detection limits by the beginning of the second year as they failed to grow on primary isolation media containing antibiotics. However, strains Pw-2R and Sw5-RN grew on isolation medium with antibiotics if they were first isolated on agar without antibiotics and then replica-plated onto agar media containing antibiotics. A similar temporary loss of antibiotic resistance has been observed with endophytic bacteria, but our results suggest such masking may be of much wider significance than previously thought. If it commonly occurs in rhizosphere colonizing bacteria as well as endophytes, significant underestimates of bacterial population sizes in similar environmental samples may result.

The effect of cultivation technique on root architecture of young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees on surface water gleys

The research on the impact of soil cultivation/drainage practices upon root architecture of young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees reported in this article was carried out in the period from 1995 to 1997. A total of 279 trees between five and eight years of age were excavated on three sites in the mid-west of Ireland. The general soil type was surface water gley. Horizontal and vertical root spread was found to be related to the size of the tree. Larger trees in the machine mound and mole and mound treated plots tended to have greater root spread compared to the smaller trees in the moled and uncultivated plots. Between the two sampling periods in 1995 (at the age of 5 years) and 1997 (at the age of 7 or 8 years) the percentage root distribution decreased close to the root stock and increased further out. However, at all three sites very little of the root cross sectional area was found beyond 60 cm from the root stock in either the vertical or the horizontal directions, even after 7 growing seasons. Generally the location of the centre of gravity of the tree root systems was not affected by cultivation treatment, nor was it found to differ significantly from the ideal co-ordinates of (0,0). Therefore, most of the root systems appeared to be symmetrical.

Comparative studies on the fine root status of healthy and declining spruce and beech trees in the Bavarian Alps and occurrence of Phytophthora and Pythium species

Investigations on root and crown status of spruce and beech were carried out on selected trees in the ‘Werdenfelser Land’ area (Bavarian Alps, Southern Germany). In addition, the association of fine root pathogens of the genera Phytophthora and Pythium with the trees’ rhizosphere was studied. In a variety of stands representing various site conditions, soil and root samples were taken from 12 spruce (Picea abies) pairs and eight beech (Fagus sylvatica) pairs. Each pair consisted of a healthy and a declining tree as indicated by crown transparency. The root status was characterized using a set of parameters, and correlations between crown and fine root status were observed. In spruce, most parameters decreased significantly with increasing crown transparency, whereas in beech, correlations were less pronounced. The total number of lateral roots per cm small root (diameter 2–5 mm) was significantly lower in both species for declining trees compared to healthy trees. Pythium spp. were isolated from 15 of 24 soil samples taken from under spruce, and from eight of 16 samples from under beech. Phytophthora citricola was found in two beech stands only. Among the isolated species, Pythium anandrum, Pythium inflatum and Pythium acrogynum were identified according to morphological features. After polymerase chain reaction‐restriction fragment length polymorphism analysis, residual Pythium isolates were assigned to four different groups. No crown transparency‐dependent differences in isolation frequency were found. In soil infestation tests, all species tested caused root damage on both young spruce and beech plants, with P. citricola being the most aggressive pathogen. Additionally, Pythium‐infected beeches showed severe leaf chloroses and necroses. Due to their low isolation frequency, Phytophthora spp. are not considered to play a major role in the decline of spruce and beech in the investigated area. Pythium spp., however, were isolated frequently, showed pathogenicity towards the fine roots of spruce and beech, and are therefore considered to be at least contributing factors in the decline of Bavarian mountain forests.

Influence of Soil Type on the Effects of Elevated Atmospheric CO2 and N Deposition on the Water Balance and Growth of a Young Spruce and Beech Forest

Sixteen open-top chambers, each equipped with two non-weighablegravity-drained lysimeter compartments, were used to investigate the impacts of elevated atmospheric carbon dioxide (CO2) concentration and nitrogen (N) deposition on the water relations and growth of young model forest ecosystems on two different types of soils. The same vegetation of a mixed spruce and beech overstorey and various herbs in the understorey was planted in all treatments on both soils. The soils were repacked on top of a drainage layer. Four combinations of treatments were applied in four replicates each: ambient (370 cm3 m-3) CO2 + low (7 kg N ha-1 a-1) N deposition, ambient CO2 + high(70 kg N ha-1 a-1) N deposition, elevated (590 cm3 m-3) CO2 + low N deposition, and elevated CO2 + high N deposition. After canopy closure, treatment effects on evapotranspiration and growth during the third year of study were very different for the two soils.On the acidic sandy loam, elevated CO2 enhanced growth(leaf biomass +21%, roots +27%) at reduced evapotranspiration (–9%). High N deposition increased aboveground growth even more strongly (+50%), but also increased evapotranspiration (+16%). Together, elevated CO2 and high N had a more than additive fertilizer effect on growth, while their effects on evapotranspirationcompensated. On the calcareous loamy sand, elevated CO2not only tended to enhance growth (leaf biomass +17%, roots +20%), but also increased evapotranspiration (+5%).On this soil, aboveground growth was stimulated by N only incombination with elevated CO2, but less than on the acidic soil, while evapotranspiration (–6.5%) and root growth into the subsoil (–54%) were decreased by increased N deposition at both CO2 concentrations, in contrast to the N treatments on the acidic sandy loam. The influence of the soil on the observed ecosystem responses canbe interpreted in terms of the concept of optimal resource allocation.

Seasonal Susceptibility of Boreal Plants to Glyphosate I. Blue-Joint Grass and Black Spruce

Abstract Seasonal susceptibility and posttreatment recovery of blue-joint grass (Calamagrostis canadensis [Michx.] Beauv.) to glyphosate (N-[phosphonomethyl] glycine) were examined in a young black spruce (Picea mariana [Mill.] B.S.P.) plantation. In 1990, two rates of the herbicide (1.1 and 1.7 kg ae/ha) were applied on July 19, August 1, 15, and 29, and September 10 and 29 using a backpack sprayer. Although differences between rates were marginal, time of application strongly influenced post-treatment cover of blue-joint grass. Compared to the untreated control, glyphosate applied between August 1 and September 10 significantly reduced cover of blue-joint grass for 3 yr after treatment and increased growth of black spruce for at least 5 yr. The optimum period of glyphosate efficacy corresponded to the end of blue-joint grass's full flowering and beginning of aboveground senescence. North. J. Appl. For. 17(4):141–148.

POPULATION TRENDS OF A SPECIALIST HERBIVORE, THE SPRUCE BUD MOTH, IN YOUNG WHITE SPRUCE STANDS

AbstractWe investigated the factors responsible for changes in abundance of the spruce bud moth, Zeiraphera canadensis Mut. and Free. (Lepidoptera: Tortricidae) in one unmanaged and several managed (i.e., planted) young white spruce, Picea glauca (Moench.) Voss (Pinaceae), stands in northern New Brunswick, Canada. Spruce bud moth densities declined when one stand closed (branches from neighbouring trees overlapped) and had already declined in another similarly aged closed stand, but remained high on 8- to 22-year-old open-grown white spruce. Both the intrageneration survival rate and the egg-to-moth ratios increased when population densities increased, and generally decreased, although the egg-to-moth ratio fluctuated, during the population decline in a managed stand. Increases in intrageneration survival rates of spruce bud moth on 5- to 10-year-old trees were due to increased larval or pupal survival. Crown closure explained 76 and 81% of the variability in larval and intrageneration survival, respectively, in four managed stands. The strong inverse relationship between larval survival and degree of crown closure resulted in statistically significant but spurious relationships between larval survival and larval density and between larval survival and tree age. A reduction in larval survival occurring as degree of crown closure increased was the most important factor influencing decreases in intrageneration survival at the beginning of population decline. Increases in the egg-to-moth ratio during the population increase, and decrease during population decline, suggested that dispersal behaviour and (or) realized fecundity of females also contributed to annual changes in population.