Sitka Spruce Plantation Research Articles

The impacts of atmospheric n inputs on throughfall, soil and stream water interactions for different aged forest and moorland catchments in Wales

A study of inorganic-N concentrations in streams, soil waters, throughfall and rainfall was conducted for one year in five moorland and 20 Sitka spruce plantation catchments in upland Wales. The forest ages ranged from 10 to 55 yr. Highly significant positive relationships with forest stand age existed for inorganic-N concentrations in streamwater, B and O horizon soil waters and throughfall. Inorganic-N in streams and B horizon waters was entirely NO3−. Inorganic-N fluxes in throughfall also showed a significant, positive relationship with stand age. Throughfall flux of inorganic-N in the oldest stand was 25.1 kgN ha−1 yr−1, double that in incident rainfall.

Nitrate leaching from a Sitka spruce plantation and the effect of fertilisation with phosphorus and potassium

Mature Sitka spruce ( Picea sitchensis (Bong.) Carr.) plantations in the Beddgelert area of North Wales have comparatively large concentrations and leaching rates of soil water nitrate. To determine whether elimination of any phosphorus or potassium deficiency in the trees can result in increased demand for N and reduce nitrate leaching rates, P and K fertiliser was applied at two rates (P1K1 and P2K2) in a randomized block experiment. Soil water nitrate concentrations dropped significantly in the P2K2 treatment, compared with the Control, for two growing seasons following application of the fertiliser. There was no significant effect of the P1K1 treatment. Demand for N, P and K by the trees was estimated using root bioassay techniques. Three months after application of the fertiliser, uptake of all three nutrients from solution by excised roots was significantly lower in the P1K1 treatment, and very significantly lower in the P2K2 treatment, compared with the Control. These results imply that at least part of the demand for P and K in the trees had been satisfied by increased uptake of the applied fertiliser, resulting in an increased uptake of N. Foliar analysis confirmed that additional N was present in the trees in the P2K2 treatment. Fertiliser application is a technique which could reduce nitrate leaching rates. Only at sites where nitrate is a major component of the total inorganic anion concentration will reduction in nitrate concentration reduce acidification rates significantly.

Extreme wind speeds over a Sitka spruce plantation in Scotland

Hourly-mean wind speed, gust factors and turbulence intensity at the top of a Sitka spruce plantation (of maximum canopy height 16 m) were recorded continuously over a 15 month period. The maximum hourly-mean wind speed recorded was 13.2 m s −1, the turbulence intensity was in the range 0.33–0.54 depending on mean wind speed and the gust factor was 2.1 on average. The cumulative distribution of wind speeds was found to follow the Weibull distribution with parameters k = 1.55 and c = 3.46 m s −1. From this distribution the parameters of the Fisher-Tippett function describing the cumulative distribution of the annual extreme hourly wind speeds were estimated. Hence the most likely extreme in a 50 year period was calculated to be 16.8 m s −1. The characteristics of the variation in wind speed were found to be in acceptable agreement with those from theoretical and empirical descriptions of the effect of surface roughness on wind speed developed for the UK building industry. Turbulence intensity was found to be lower than predicted by theory at high mean wind speed. Closer agreement with the experimental results was achieved when the surface roughness in the theory was allowed to decrease with increasing mean wind speed, as is likely to happen when trees bend. It is concluded that the methods developed by the building industry for predicting wind climate are an adequate basis for calculating the risk of wind damage in coniferous plantations. This conclusion is important because there are few long-term measurements in forested areas.

Impact of foliar and soil applications of nitrogen on the nutritional status of a young Sitka spruce plantation

In order to ascertain the effect of high nitrogen deposition on trees, a novel method was developed to apply wet-deposited nitrogen to the canopy of a young Sitka spruce plantation. Nets were soaked in salts of ammonium or nitrate and then hung above the tree canopy, enriching the rain passing through. This application method was compared with conventional nutrient additions to the soil. Applications of 10 kg N ha −1 month −1 resulted in enhanced foliar nitrogen levels, no change in potassium or calcium, and a small decrease in magnesium and phosphorus concentrations. Nitrate applications did not increase the low levwl of nitrate reductase activity in the foliage, but there was some evidence for induction in the roots. Sitka spurce plantations in the UK appear to have the capacity to utilise atmospheric inputs of nitrogen without adversely affecting the foliar cation status; however, phosphorus deficiencies could be exacerbated or induced.

Relationships between weather patterns, Sitka spruce (Piceasitchensis) stress, and possible tip weevil (Pissodesstrobi) infestation levels

Vapor pressure deficit (VPD) regimes were determined for Sitka spruce (Piceasitchensis (Bong.) Carr.) plantations growing in coastal and inland sites of the Olympic Peninsula of Washington State. Relationships between VPD regimes on patterns of stomatal conductance, stem hydration, and xylem pressure potential were examined in Sitka spruce saplings growing on these two sites. These patterns and VPD regimes were analyzed in relation to areas known to sustain either low or high infestation levels of the tip weevil (Pissodesstrobi (Peck) (Coleoptera: Curculionidae)). High VPD regimes of inland Sitka spruce plantations were frequently observed in the summers and were associated with clear days and on-shore breezes; in synchrony with high VPD regimes, the trees of these areas exhibited water stress and decreased photosynthesis. In turn, these factors might contribute to lowered host defenses against tip weevil attacks. Coastal sites generally experienced lower VPD regimes and, consequently, infrequent water stress and stomatal closure, and spruces growing near the coast were mostly associated with low tip weevil attack.

MerlinsFalco columbariususing crow nests in Kielder Forest, Northumberland

Since 1961 the Northumbria Ringing Group has monitored a population of Merlins breeding in Kielder Forest, Northumberland. Prior to 1979 Merlins bred at traditionally used sites mostly on the ground in Heather. In 1979 the first nest was located in a crows nest along the moorland edge of a young Sitka Spruce plantation. This nesting habit has increased, and by 1990 over 50% of the population were breeding in crows' nests in conifers. This switch in the type of nest sites has coincided with large areas of forest reaching an age suitable for crows to nest in. Merlins breeding in conifer forests had similar clutch sizes to those using traditional ground nests, but in conifer sites, brood sizes were 70% larger. Throughout the course of this study (1978–90) the Merlin population increased by 71% to 24 pairs in 1990. A low point was reached in 1982/83 when only 10–11 pairs bred, after this tree-nesting increased and so did the population.

Use of Burrows and Movements of Wild Rabbits (Oryctolagus cuniculus) in an Area of Hill Grazing and Forestry

SUMMARY (1) Radio-collared rabbits were followed throughout the year on an area of upland grazing and forestry plantations in the Scottish Borders to study their use of burrows and cover for refuge during the day. (2) Observations on the distribution of radio-collared rabbits, faecal pellets and burrows suggested an isolated, discrete population, using an area of approximately 37 ha. Trapping out at the end of the study gave a breeding density of approximately two rabbits ha-'. (3) A few rabbits were permanently in burrows in the middle of a field in the centre of the area. The remainder, 86% of the population, were to be found during the winter on the surface in surrounding forestry plantations. (4) Young rabbits at the end of the summer were initially to be found in burrows, but most of these left during November and went to live in the plantations. The youngest rabbits were the last to leave. (5) Ferreting the warrens in the middle of November suggested that all burrows within 70 m of Sitka spruce plantations were empty. (6) The movements of radio-collared rabbits in the plantations were not affected by the removal of those in burrows in the field in November and rabbits were not seen again in the field until the following February. (7) Surface-living rabbits were found further into the trees and away from the field edge as the winter progressed (up to 250 m) but started to move back to the field during the spring. (8) The results are discussed in relation to the causes of surface living in rabbits from the viewpoints of social behaviour and avoidance of predation, and in relation to the effectiveness of gassing burrows as a method of rabbit control in afforested areas.

Denitrification in a Sitka spruce plantation and the effect of clear-felling

To determine the rate of denitrification from an upland plantation forest of Picea sitchensis, a field coring and laboratory incubation technique was developed. The method was tested in the laboratory to ensure that the C 2H 2 block worked in the acid, organic, poorly drained peaty gley soil under investigation. Similarly, the relationship between denitrification rate and temperature was determined, so that field estimates could be made based on the laboratory incubations. The technique was used to monitor denitrification rates in standing and felled forest areas, and to evaluate annual N losses. The total loss of N from the standing forest through denitrification was estimated to be 3.2 kg N ha −1 over the year studied and, of this loss, approximately 80% was as N 2O. Denitrification increased as a consequence of clear-felling, and an estimated 9–40 kg N ha −1 year −1 were lost in the first 2 years after felling. Denitrification can be a significant component of the forest N cycle, yet has been frequently assumed to be negligible. Although the absolute amounts of N lost from forests in this way may be small, they can be of comparable magnitude to pollutant inputs, and contribute significant quantities of N 2O to the atmosphere.

The controls on dissolved nitrogen losses following two intensities of harvesting in a Sitka spruce forest (N. Wales)

The controls on dissolved nitrogen losses following conventional and whole-tree harvesting were investigated in a Sitka spruce plantation in N. Wales (UK). Lysimeters containing the soil organic horizons were established with the treatments brash, ground vegetation and Sitka spruce seedlings in a limited factorial design; other treatments designed to investigate the effect of the physical protection provided by the brash and the brash throughfall on underlying organic horizons were also included. The lysimeter leachates were collected and analysed weekly for 15 months. The brash present following conventional harvesting increased nitrate leachate losses two fold during the experimental period relative to control lysimeters containing only soil organic matter with no vegetation or brash. Increased inputs of soluble organic nitrogen, potassium and phosphorus in the brash throughfall were found relative to the incoming rain. However, the increased nitrate loss may be attributable to improved microclimatic conditions stimulating mineralisation and nitrification rates beneath the brash as similar effects on nitrate loss were observed with an inert ‘artificial brash’ cover on the organic material. The presence of brash also increased hydrogen and aluminium loss from the organic horizons. The presence of less than 50% cover of Agrostis capillaris L., which establishes quickly in the absence of brash, reduced nitrate losses to 19% of the control and 10% of that from the brash treatment. Soluble organic nitrogen losses were unaffected and were an important component of nitrogen leachate losses.

Nitrogen sinks following two intensities of harvesting in a Sitka spruce forest (N. Wales) and the effect on the establishment of the next crop

The importance of the ground vegetation and soil microbial biomass as sinks for nitrogen following conventional (CH) and whole-tree (WH) harvesting in a Sitka spruce plantation in N. Wales (UK), were investigated. Lysimeters containing the organic horizons were established with the treatments brash, Agrostis capillaris (L.) and/or Sitka spruce ( Picea sitchensis (Bong.) Carr.) seedlings in a limited factorial design. Following a period of 15 months, during which chemical analysis of the lysimeter leachates was carried out, the lysimeters were destructively sampled and the vegetation and soil microbial biomass nitrogen pools measured. The effect of the different treatments on the decomposition rate of the organic matter and the growth and nutrient status of the young Sitka spruce trees was also determined. A comparison of the nitrogen pools and the cumulative leachate results identified the grass as the major sink for nitrogen with uptake over a 15 month period equivalent to 2.6 g N m −2 at 50–75% cover. Uptake by the Sitka spruce was also significant with net uptake ranging from 0.6 g N m −2 when growing with the grass to 1.74 g N m −2 when planted within a pile of brash. The microbial biomass nitrogen pool was unchanged by the presence of the grass species but was significantly increased in the lysimeters containing brash and/or Sitka spruce (possibly owing to the presence of mycorrhizal fungi). The microbial N pool was greatest in the treatment containing the combination of the trees planted within the brash, with 3.49 (±0.52) g N m −2 as microbial biomass N compared with 1.99 (±0.24) g N m −2 in the control lysimeters containing neither brash nor trees. The growth of the Sitka spruce was highly variable within treatments, however, the mean biomass m −2 doubled if planted within the brash, and also resulted in elevated foliar concentrations of nitrogen, potassium and phosphorus. When in competition with the grass, tree biomass was halved, tree needles appeared chlorotic and phosphorus concentrations were halved. The management implications for harvesting intensity on upland sites are considered.

Nutrient Accumulation in Vegetation Following Conventional and Whole-Tree Harvest of Sitka Spruce Plantations in North Wales

Nutrient Accumulation in Vegetation Following Conventional and Whole-Tree Harvest of Sitka Spruce Plantations in North Wales

Dissolved inorganic nitrogen concentrations and fluxes in three British Sitka Spruce plantations

A catchment approach was used to estimate mean dissolved inorganic-N concentrations and fluxes through three mature Sitka spruce plantations at Beddgelert (north Wales), Plynlimon (mid-Wales) and Kershope (Cumbria). Dissolved inorganic-N in bulk precipitation, throughfall, stemflow, soil water at 4 or 5 depths, and streamwater was measured every two weeks for periods of 1 or 2 years at all three sites. Bulk precipitation inputs at the three sites varied from 6 to 10.4 kg N ha-1 a-1 and stream outputs varied from 6.4 to 13.6 kg N ha-1 a-1. Beddgelert Forest had the highest inputs and outputs and is “Nitrogen saturated” according to certain Scandinavian criteria (Nilsson, 1986). All three sites had much higher outputs than might be expected from the magnitude of the inputs, since conifer forests are normally regarded as being ‘conservative’ with respect to N. Only at Plynlimon were reductions in dissolved inorganic N flux or concentration observed from bulk precipitation to throughfall and soil waters. At the other two sites, the tree canopies did not assimilate N in incoming rainfall, and active nitrification resulted in high concentrations of nitrate in soil and streamwater. It is proposed that many mature western upland Sitka spruce plantations may behave in a similar manner with respect to dissolved N, in contrast to sites in eastern Scotland where rates of nitrification are slower and nitrogen appears to be less available to plantation trees.

Hydrogeochemical variations in Hafren forest stream waters, Mid-Wales

Results are presented for a study attempting to assess the effects of conifer planting/harvesting and acidic oxide deposition on streamwater quality in a 25 to 45-year-old sitka spruce plantation on acid moorland. This is undertaken to demonstrate the application of a multi-element survey in providing ‘chemical fingerprints’ for describing hydrological and hydrochemical controls within catchments. Hafren forest streamwater chemistry varies for different components: nitrate, bromide, total iodine and total organic carbon show seasonal oscillations varying in phase and amplitude; aluminium and hydrogen ion concentrations vary as a function of flow; manganese and cobalt remain approximately constant except under very dry conditions when concentrations reduce by up to 10 fold. No direct link exists between rain and streamwater chemistry: streamwater chemistry variations are determined primarily by hydrological and chemical reactions in the surface organicrich soils and the underlying inorganic soils/bedrock. Reactions in the organic-rich horizons involve the generation of acidic conditions and the mobilization/transport of transition metals that can be easily hydrolysed. Biologically mediated breakdown processes determine, in part, the hydrochemical behaviour of dissolved organic carbon, the nutrients, bromine and iodine. Reactions in the inorganic zones involve hydrogen ion consumption and the release of calcium and magnesium. Bicarbonate ions are generated by deprotonation of biogenically derived H 2 CO 3 and the decompostion of calcium carbonate in the bedrock. The initial effects of forest clearfelling are demonstrated; increases in nitrate and potassium occur. A simple mixing model is presented to show that either a large proportion of the storm water is derived from ‘non-hillslope’, ‘groundwater’, sources, or major modifications occur as soil water passes rapidly to the stream; whichever process is operative, it has not been identified directly within the catchment monitoring programme.

The effect of clearfelling a Sitka spruce ( Picea sitchensis) plantation on solute concentrations in drainage water

Water samples were collected from the drainage system of a Sitka spruce plantation at weekly intervals for six years. The drainage system had been designed to divide the plantation into a series of artificial catchments, three of which were designated experimental plots and clearfelled in the second year of sampling while a fourth was the control plot which remained unfelled until the end of the study. Prior to felling, solute concentrations were similar for all plots. Concentrations of nitrate, potassium and phosphate all rose following felling. Nitrate concentrations peaked one year after the end of felling and returned to levels similar to the control plot in the fourth year after felling. Potassium and phosphate peaked in the second year after felling but had not returned to control levels by the end of the study, although seasonal patterns had become established, with lower concentrations in summer. Concentrations of sulphate, sodium and chloride declined as a result of felling and remained lower than the control at the end of the study. There was a very slight fall of pH and aluminium concentration after felling, relative to the control. The three experimental plots behaved in a similar way for all ions except phosphate and iron which were released in greatest quantities from the least intensively drained plot.

Effect of harvest intensity and ground flora establishment on inorganic-N leaching from a Sitka spruce plantation in north Wales, UK

Inorganic-N concentrations in soil solution of whole tree harvest (WTH) and conventional fell (CF) plots were monitored for two years before felling and four years after felling. Concentrations in the mineral soil after felling were higher than in standing forest for up to 14 months in both felling treatments. In the WTH plots inorganic-N concentrations then dropped steadily until four years after felling they approached zero. In contrast, inorganic-N concentrations of the CF plots remained comparatively large. Inorganic-N was dominated by nitrate throughout the period of the study, and especially in the mineral horizons.

The effect of spacing on Sitka spruce weevil damage to Sitka spruce

Tree diameter, height, form, and number of stem defects were recorded in 26-year-old plantations of Sitka spruce, Piceasitchensis (Bong.) Carr., established at three initial spacings (2.74 × 2.74, 3.66 × 3.66, and 4.57 × 4.57 m). These plantations were heavily attacked by the Sitka spruce weevil, Pissodesstrobi Peck, from an early age. Denser plantations sustained a lower intensity of attack than the more open plantations. Although the three spacings had similar average number of stem defects per tree, trees in the close spacing had a significantly higher frequency of trees of good form relative to the more open plantations. It was concluded that trees planted at close spacing had lower levels of weevil damage. As a management regime, it is recommended that Sitka spruce plantations be started at close spacing (2.74 × 2.74 m) and precommercially thinned at age 25. By this age trees will average about 19 cm in dbh and 12 m in height, thus ensuring a first log of good quality.

Foliar analysis and response of fertilized chlorotic Sitka spruce plantations on salal-dominated cedar–hemlock cutovers on Vancouver Island

A series of microplot and conventional plot trials were used to determine the nutritional status and required nutrient additions to bring young chlorotic Sitka spruce (Piceasitchensis (Bong.) Carr) plantations out of "check." Check occurs on clear-cut and burned old-growth western red cedar (Thujaplicata Donn ex D. Don) and western hemlock (Tsugaheterophylla (Raf.) Sarg.) stands in the Coastal Western Hemlock biogeoclimatic zone growing on deep morhumus Podzols invaded by dense salal (Gaultheriashallon). Microplot trials identified the requirement for N and P. Checked trees responded to fertilization immediately with a 4- to 8-year temporary increase in leader length. Grubbing out of aboveground salal did not improve tree nutrition. There is a close parallel to "heather check" noted with Sitka spruce in British and Irish moorlands; a possible allelopathic effect of salal is suspected. It is concluded that one or more N and P additions are required to establish crown closure. Fertilized Sitka spruce show a high incidence of spruce weevil attack. The deficient and optimum foliar nutrient concentrations developed in Britain for the diagnosis of Sitka spruce appear to be applicable.

Some Effects of Afforestation on the Flora and Fauna of an Upland Sheepwalk During 12 Years After Planting

(1) Following afforestation of an upland sheepwalk, the effects of reduced grazing, ground preparation and the early stages of plantation development induce marked changes in the frequency of occurrence of vascular plants and of vertebrate animals. (2) On an area of 139 ha, the number of vascular plants recorded in systematically placed quadrats changed little in the first 9 years: eighty-one remained whilst twenty-seven disappeared and were replaced by twenty-nine others. Quadrats placed in Sitka spruce and western hemlock plantations had significantly fewer plant species after 9 years. Grasses and rushes increased most in frequency whilst species of wet habitats and of small stature became less frequent. (3) An estimated 271 pairs of birds, of twenty species, nested on the study area in 1972, but in 1984, 724 pairs from twenty-five species nested, of which only seven species remained from 1972. (4) Tests of association between selected feeding or breeding birds and mammals and site characteristics suggested significant positive and negative associations with vegetation, tree species, tree height and woodland edge. Bird densities showed large variations within the study area, particularly in relation to tree height, and whilst whinchat densities were less than reported elsewhere, coal tits and goldcrests were present in greater densities. A flight pond provided good bags of duck for at least 8 years.

Nitrate leaching from a felled Sitka spruce plantation in Beddgelert Forest, North Wales

Abstract. Soil water samples from five horizons in a stagnopodzol were collected regularly over a five‐year period in a Sitka spruce plantation at Beddgelert Forest, North Wales. Samples were analysed for nitrate‐N and ammonium‐N. After felling, inorganic‐N concentrations increased markedly in the C horizon, generally decreased in the surface horizons and showed little change in the E and Bs horizons. Fluxes through the C horizon increased after felling from 10 to 70 kg N ha‐1 a‐1, the latter being equivalent to leaching losses in intensive lowland agricultural systems. Trends in concentration and flux were attributed to seasonal temperature and rainfall variations.Nitrate‐N dominated the dissolved inorganic‐N, especially in the lower horizons. Nitrification was obviously active, despite the acid soil. Nitrate leaching losses occurred, even beneath the standing crop. On felling, cessation of nitrogen uptake allowed substantially more nitrate to be leached as no alternative sink was immediately available.

Development of a pheromone monitoring system for the winter moth, Operophtera brumata (L.), in apples and in sitka spruce

Winter moth ( Operophtera brumata) can be an important pest both in top fruit orchards and in Sitka spruce plantations. Monitoring systems are required in both these crops to identify areas at risk and so to optimize the use of insecticide treatments. This paper is a report of work carried out to determine some of the requiments for a working monitoring system baed on the recently identified pheromone (3 Z,6 Z,9 Z)-1,3,6,9-nonadecatetraene. Experiments were carried out to discover the best trap design, pheromone dose level, lure change interval and trap height. Recommendations for the systems are made.