Tree and livestock productivity in relation to tree planting configuration in a silvopastoral system in North Wales, UK

Silvopastoral systems in Europe offer the potential of introducing environmental benefits while at the same time increasing the diversity of farm outputs. The establishment of new silvopastoral systems by planting young trees into existing pasture was investigated at a site in North Wales, UK. Two tree species, sycamore (Acer pseudo-platanus L.) and red alder(Alnus rubra Bong.), were planted into pasture at a range of densities and planting arrangements. Growth of trees planted in farm woodland blocks (2500 stems ha^–1) was compared with the growth of trees planted at 400 stems ha^–1 in clumps and dispersed throughout the plot and at 100 stems ha^–1 (dispersed). Over the first six years after planting, alder trees were significantly taller and larger in diameter than sycamore. Sycamore trees planted at close spacing in farm woodland or clumped arrangements were significantly larger in diameter than widely spaced sycamore at 100 and 400 stems ha^–1. Livestock productivity was unaffected by the presence of trees during the six-year establishment phase of the system. The planting of trees in a clumped pattern appears to combine silvicultural benefits to tree growth with agricultural benefits of maintaining livestock production while trees are established.This revised version was published online in November 2005 with corrections to the Cover Date.     

Growth and mortality in underplanted tree seedlings in response to variations in canopy closure of Norway spruce stands

Six broadleaved tree species and Picea abies (L.) Karst. wereplanted under spruce plantations of varying densities, in Sweden.Treatments included control (994 stems ha^–1), dense (538stems ha^–1), sparse (294 stems ha^–1) and gap (0stems ha^–1) overstory treatments. There was an increasein height and diameter growth from control to sparse overstorytreatment of all underplanted tree species except for ash (Fraxinusexcelsior L.) and Norway maple (Acer platanoides L.). Site conditionsmay have hampered the growth of these species, as well as wildcherry (Prunus avium L.). Both oak (Quercus robur L.) and sprucehad greater growth in the gap treatment, relative to the othertreatments. Insecticide application did not influence seedlinggrowth or survival. The performance of beech (Fagus sylvaticaL.), lime (Tilia cordata Mill.), spruce and oak was consistentwith shade tolerance ranking. Beech and lime had a very highsurvival rate, even under the densest canopy. The growth andmortality of ash, maple and wild cherry differed significantlyfrom what was expected. This experiment demonstrated significantvariation in interspecific growth and mortality between sevenplanted tree species in relation to canopy density. Correctsite and species selection is crucial when underplanting inshelterwood systems.     

林龄、采伐方式对大叶相思萌芽更新的影响*

在海南省琼海县进行了不同林龄、不同采伐方式对大叶相思萌芽更新影响的研究，同时比较了保留不同萌条数量的萌芽林生长表现。结果表明：（１）林龄对伐桩萌芽率没有显著影响，但对伐桩存活率及萌条的径、高生长影响显著或极显著。林龄越大，萌芽更新效果越差；（２）皆伐和隔行采伐对大叶相思伐桩的萌芽率、萌条数量和存活率均无显著影响，但对萌条的径、高生长影响极显著。试验证明对大叶相思林分施以隔行采伐通过萌芽更新建立复层     

Stress resistance levels change little during dormancy in ash,sessile oak and sycamore seedlings

The physiological status of ash (Fraxinus excelsior L.), sessile oak (Quercus petraea (Matt.)) and sycamore (Acer pseudoplatanus L.) seedlings sampled from nurseries in Ireland between October and May, 1995/1996 and 1996/1997 was investigated. The results of heat treatments applied to taproots in vitro and evaluated using root electrolyte leakage (REL) indicated that sycamore was more easily damaged than the other species but lift date effects were small in all species. Dormancy release began later each year in ash (mid-November) than in oak or sycamore (late October to early November). The results of the REL and other data indicated that there was little change in stress resistance from November to about March (and April for some parameters). Sycamore was most active (highest shoot xylem pressure potential, REL, and root growth potential) during the winter, suggesting that adverse handling during this period is likely to reduce plant quality than in ash or oak. Field performance was good regardless of lifting/planting date.     

Growth and nutrition of young European ash (<Emphasis Type="Italic">Fraxinus excelsior</Emphasis> L.) and sycamore maple (<Emphasis Type="Italic">Acer pseudoplatanus</Emphasis> L.) on sites with different nutrient and water statuses

This study aimed to improve knowledge about the nutritional status, site requirements and site classification for European ash (Fraxinus excelsior L.) and sycamore maple (Acer pseudoplatanus L.) by reinvestigating young plantations from 1991/1992 on windfall-affected areas in Bavaria/Germany after another decade. Compared to the first survey in 1995, most stands improved their nutritional status until 2006. With the data set of element concentrations in leaves of ash and sycamore available, the range of adequate nutrition could be determined for these species in the pole stage phase. Both species show considerable height growth on a wide range of sites. Mean annual height growth of dominant sycamore trees increased with rising foliar N or P concentrations but not for Ca, Mg, K, Mn, Fe and Al. For ash, there was no relationship between the foliar nutrient level of any element and mean annual height growth. However, total height around age 20 was favourably influenced by high base saturation and a good water supply at well-drained sites. On acid soils, where nutrients are delivered by subsurface water flow, well-growing stands are found as well. Soil water status according to the state forest soil classification had no significant impact on mean annual height growth. Ash and sycamore show reduced productivity on some (moderately) dry soils and fail on poorly drained moist sites. Based on these results, the classification of forest sites suitable for ash and sycamore within the Bavarian study sites was revised. Dedicated to Professor Dr. Karl-Eugen Rehfuess on his 75th birthday.     

The sprouting ability of the main tree species in Central European coppices: implications for coppice restoration

Coppicing was widespread across Europe for many centuries, but during the last 150?years, it has been largely abandoned. Most of the former coppices have been converted to high forest, especially in Central and northwestern Europe. Recently, there has been renewed interest in restoring coppices in some regions, primarily for biomass production and nature conservation. However, there is limited information on the sprouting ability of European tree species, which is the key prerequisite for successful coppice restoration. To address this gap, we evaluated the post-harvest stump sprouting of the three main species of Central European coppices—sessile oak (Quercus petraea (Mattuschka) Liebl.), European hornbeam (Carpinus betulus L.) and small-leaved lime (Tilia cordata Mill.)—in relation to the stump diameter and density of residual trees. Lime and hornbeam resprouted from stumps of all diameters, but sprouting ability declined with increasing stump diameter in sessile oak. Lime produced greater numbers of sprouts with greater diameters and heights than either oak or hornbeam. The number of sprouts per stump increased with stump diameter in all three species as did the height of lime and hornbeam sprouts, whereas there was no such effect on the height of oak sprouts. The sprouting of hornbeam and oak increased and decreased, respectively, with an increasing density of residual trees. In conclusion, our study shows that all of the studied species are able to resprout even at an old age and after a long period of neglect; however, there were important differences among the species. The results also indicate that the age of the parent trees at the time of cutting may significantly affect the tree species composition of a newly restored coppice.     

Estimating the maple syrup production potential of American forests: an enhanced estimate that accounts for density and accessibility of tappable maple trees

This paper examines the maple syrup production potential of American forests by analyzing Forest Inventory & Analysis (FIA) data provided by the US Forest Service on the resource of sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) trees in twenty states. The analysis is based on tree species and size (diameter at breast height, or dbh), ownership category, jurisdiction, the density of maple trees in a stand, and the distance of the stand to an access road. Although there are over 2 billion sugar and red maple trees of tappable size growing in US forests, when narrowed down according to the attributes of an optimal ‘sugarbush’, there are 100 million potential taps from sugar maples alone and 286 million potential taps with sugar and red maples combined. Overall, 45 % of the tappable-size maple trees are found in stands whose density is not high enough to support commercial sap extraction whereas only 6 % are found in stands that are at least 1.6 km from an access road. The ten states with commercial maple syrup industries have a much higher percentage of their maple trees occurring in stands of optimal density and also contain a higher percentage of sugar maple than red maple trees. States that are utilizing the highest percentage of their potential sugarbushes include Vermont and Maine, whereas states that have significant room for expansion include Michigan, New York, and Pennsylvania.     

Fine root biomass,distribution, and production in young pine-hardwood stands

Patterns of fine root biomass, production, and distribution were estimated for pure stands and mixtures of three-year-old loblolly pine (Pinus taeda L.) with red maple (Acer rubrum L.) or black locust (Robinia pseudoacacia L.) on the Virginia Piedmont to determine the role of fine roots in interference between pine and hardwood tree species. Estimates were based on amounts of live and dead fine roots separated from monthly core samples during the third growing season after planting. Live and dead fine root biomass and production varied by species, but mixtures of loblolly pine and black locust generally had greater fine root biomass and fine root production than pure stands or loblolly pine-red maple mixtures. Hardwood species had greater live fine root biomass per tree in mixtures with pine compared to pure stands. Greater live fine root biomass in pine-locust stands may be attributed to differential utilization of the soil volume by fine roots of these species. For all stands, approximately 50% of live five root biomass was located in the upper 10 cm of soil.     

Factors influencing the formation of heartwood discolouration in sycamore (<Emphasis Type="Italic">Acer pseudoplatanus</Emphasis> L.)

Sycamore (Acer pseudoplatanus L.) is a tree species with highly valuable wood. Similar to European beech (Fagus sylvatica L.), the stemwood of sycamore can be devalued due to the discolouration i.e. brown heart (hearwood discolouration, hereafter). This paper aims to establish the influence of tree traits and site characteristics on the formation of heartwood discolouration and the possibility of predicting the occurrence of heartwood discolouration. For this purpose, 351 sycamore trees from 38 sites in Slovenia, most of them on carbonate bedrock and in the mountain vegetation belt, were analysed. Stem analysis was carried out on all the trees and the age, diameter at breast height (dbh), height of crown base, forking and crown size, were established. On the stump and upper fronts of the first and second logs, the maximum heartwood discolouration diameter was measured. Using logistic regression, the positive influence of age, relative crown length and average diameter increment on the formation of heartwood discolouration was ascertained. Conversely, the probability of heartwood discolouration was diminished by diameter increment in the last 20 years. In the less productive sites, the probability of formation of heartwood discolouration was relatively high in small diameter trees, but it increased slowly with diameter. Tree forking also contributed to a large extent of the heartwood discolouration. After the diameter at breast height achieves 45 cm, the formation of heartwood discolouration on the first log is highly probable. As in beech, the heartwood discolouration increases along the stem axis up to a height of 6–8 m, and decreases in the higher parts of the tree.     

Eutypella parasitica naturalised in Bohemian and Polish Silesia

In 2015 and 2016, the North American maple tree pathogen Eutypella parasitica was identified in Bohemian and Polish Silesia. To date, the pathogen has been recorded in 35 locations over an area of approximately 400 km². It has been found primarily in natural stands in Silesia in several types of ravine and alluvial forests, in other natural or commercial forests, in riparian stands and in open landscapes. The proportion of diseased maples ranged between approximately 1% and 50% in certain locations. Acer pseudoplatanus was confirmed as the main host but infections were also detected on A. platanoides and A. campestre. E. parasitica damages the most valuable sycamore timber and represents a clear risk for maple cultivation in the region.     

An Exploratory,Post-Harvest Comparison of Ecological and Economic Characteristics of Forest Stewardship Council Certified and Uncertified Northern Hardwood Stands∗

ABSTRACT

As more forest entities worldwide consider pursuing Forest Stewardship Council (FSC) certification, a critical question remains on whether stand-level management impacts differ between certified and uncertified forests. To begin to answer this question, we measured forest structure on three FSC-certified stands, three uncertified stands, and six adjacent unharvested reference stands (12 stands total) composed primarily of sugar maple (Acer saccharum) on non-industrial private properties in central Vermont, USA. The certified and uncertified partial harvests reduced total tree biomass and live tree carbon storage by one-third compared to reconstructed pre-harvest conditions. Both treatments also contained significantly lower densities of saplings and some mid-size trees compared to non-harvested references due to similar impacts from harvesting. The net present value of merchantable sugar maple over 10 year projections was consistently lower on certified than uncertified stands, but this difference was insignificant at discount rates from 4–8%. The certified stands contained significantly greater total residual volumes of coarse woody debris (standing and downed) than uncertified stands, although the debris was smaller than that found in unmanaged mature forests. Overall, our data suggest that FSC-certified harvested stands in northern hardwood forests have similar sugar maple timber value, aboveground live tree carbon storage value, similar live tree structure, and greater residual coarse woody debris than uncertified harvested stands.     

Nutrient concentrations in roots, leaves and wood of seedling and mature sugar maple and American beech at two contrasting sites

Differences in sensitivity to soil conditions across tree species and developmental stage are important to predicting forest response to environmental change. This study was conducted to compare elemental concentrations in leaves, stems, and roots of (1) sugar maple (Acer saccharum Marsh.) seedlings vs. mature trees and (2) mature sugar maple vs. mature American beech (Fagus grandifolia Ehrh.) in two sites that differ in soil base saturation and pH. Both sites are located in Huntington Forest, NY, USA; one site (hereafter ‘H’) has higher soil pH and Ca, Mg, and Mn concentrations than the other site (hereafter ‘L’). Sugar maple growth at H (14.8 cm² year⁻¹ per tree) was much greater than at L (8.6 cm² year⁻¹ per tree), but the growth of beech was not different between the two sites. Leaves, roots, and stem wood of mature beech trees and sugar maple seedlings and mature trees were sampled for nutrient analysis. Foliar Ca, K, and Al concentrations were positively correlated with soil elements, but Mn concentrations were negatively correlated. Sugar maple differed more than beech between sites in foliar K and Mn concentrations. Root Mg and P concentrations reflected soil chemistry differences, in contrast to foliar concentrations of Mg and P, which were indistinguishable between the sites. In sugar maple, seedlings differed more than in mature trees in nutrient concentrations in roots, especially for Mg and Mn. Although beech was not as responsive to nutrient availability as sugar maple in foliar and root nutrient concentrations, Ca and Mg concentrations in beech wood were higher in H (52% higher for Ca and 68% higher for Mg), while sugar maple did not differ between sites. Sugar maple regeneration failure on acidic soils in the same region is consistent with our finding that sugar maple seedlings were very sensitive to nutrient availability. This sensitivity could ultimately contribute to the replacement of sugar maple by American beech in regions of low pH and base cations if base cation leaching by anthropogenic deposition and tree harvesting continues.     

Effects of climate and management history on the distribution and growth of sycamore (Acer pseudoplatanus L.) in a southern British woodland in comparison to native competitors

Sycamore (Acer pseudoplatanus L.) is an invasive, non-nativespecies in Great Britain and its management in conservationareas is controversial. Climate change adds further uncertaintyto decision making. We investigated the role of management historyin determining present-day abundance and the effects of climaticvariability on growth, photosynthesis and phenology at WythamWoods, a UK Environmental Change Network (ECN) monitoring site.Relatively few sycamore trees were found in undisturbed ancient,semi-natural woodland and recent plantations, despite beingcommon in other areas of the site. Sycamore grew more slowlythan ash (Fraxinus excelsior L.), its principal competitor,but at a similar rate to pedunculate oak (Quercus robur L.)in the period 1993–2005. There were fewer sycamore thanash seedlings, regardless of which species dominated the canopy.Growth of sycamore was slower in dry periods than wet ones andlower photosynthetic rates were measured in canopy leaves underdry compared with wet soil conditions. This study thereforesuggests that sycamore does not present a serious threat toundisturbed ancient woodland on the site and that it may eventuallydecline in areas of the site where it competes with ash, inthe absence of disturbance. It may also decline under climatechange if summer droughts become more frequent.     

Early regeneration of Fraxinus rhynchophylla in the understorey of Larix kaempferi stands in response to thinning

The effects of thinning were investigated on naturally regeneratedFraxinus rhynchophylla Hance (Korean ash) grown in the understoreyof a Larix kaempferi (Lamb.) Carr. plantation, established ona site that previously supported old growth hardwood forests.The regeneration characteristics were evaluated after thinningof the plantation (about 60 per cent of relative density wasremoved). In the naturally regenerated and mixed stands, Quercusmongolica Fisch. was the most abundant tree species in the overstorey,but the understorey of the thinned plantations was dominatedby F. rhynchophylla with six other minor tree species. Fraxinusrhynchophylla was regenerated by four propagation types includingnatural seedling, stump sprout, root sprout and layering. Beforethinning, the difference of average height growth for each regenerationtype was insignificant. One year after thinning, the stump sproutsshowed the fastest growth among the regeneration types. Heightgrowth of advance regeneration was slow in the year followingthinning but then increased rapidly surpassing the other regenerationtypes 5 years after thinning. Thinning had an effect on thecomposition of regenerated trees also by seedling, stump sprout,root sprout and layering in the understorey. Advance regenerationsoccupied the upper understorey at 5 years after thinning. Alarge number of stump sprouts emerged in the plots 1 year afterthinning, while at 5 years after thinning the occupation ofstump sprouts decreased. Root sprouts and layers faded away.Considering the early growth and the composition of understoreyF. rhynchophylla, its advance regeneration has a high potentialto develop into overstorey trees at this site.     

Equations for estimating above- and belowground biomass of Norway spruce,Scots pine,birch spp. and European aspen in Latvia

This study aims to derive allometric functions to estimate the above- and belowground biomass components of the most important tree species in Latvia. The study material included a total of 81 Norway spruce (Picea abies [L.] Karst), 102 Scots pine (Pinus sylvestris L.), 105 birch spp. (mainly silver birch (Betula pendula Roth)) and 84 European aspen (Populus tremula L.) trees sampled in 124 forest stands. The suitability of three mathematical models for the prediction of total aboveground biomass, stem biomass, total live and dead branch biomass, belowground biomass and small root biomass was evaluated. Our analysis revealed that the use of the Intergovernmental Panel on Climate Change mean default values for the root-to-shoot ratio recommended for temperate and boreal ecological zones leads to the overestimation of root biomass of young trees, especially Scots pine and Norway spruce. Our findings indicate that biomass functions recommended for other Baltic Sea countries are not appropriate for the assessment of the biomass stock in Latvia’s forests because these lead to biased estimates. The biomass functions derived in our study are recommended for reporting the biomass stock in Latvia.     

Contributions of root and stump sprouts to natural regeneration of a logged tropical dry forest in Bolivia

A major impediment to the sustainable management of tropical dry forests in Bolivia is the scarcity of natural regeneration of commercial timber tree species. Where regeneration is present, true seedlings of many species are outnumbered by vegetative sprouts from roots, broken stems, and the stumps of felled trees. This study evaluates the importance of resprouts promoted by logging operations for the regeneration of commercially important canopy tree species. The objectives of the study were: (1) to characterize stump and root sprouting behaviors of canopy tree species harvested for timber; (2) to quantify the effect of logging on relative abundances and growth rates of stump sprouts, root sprouts, and true seedlings; (3) to relate the species-specific probabilities of stump sprouting to stump diameter and stump height; and (4) to explore how sprouting varies with the ecological requirements of canopy tree species. The study was carried out 1–5 years after logging of a privately owned land in a Bolivian tropical dry forest. Twenty-seven of the 31 species monitored resprouted at least occasionally, among which Centrolobium microchaete (Leguminosae-Fabaceae) and Zeyheria tuberculosa (Bignoniaceae) were the most frequent stump sprouters, and Acosmium cardenasii (Leguminosae-Fabaceae) and C. microchaete were the most frequent root sprouters. In all species the number of sprouts declined with increasing stump diameter and stump height. The probability of stump resprouting differed among species but did not vary consistently with stump diameter, except in Z. tuberculosa in which it declined. Approximately 45% of juveniles <2 m tall of canopy tree species originated from root or stem sprouts. Light-demanding species tended to regenerate more from seeds and root sprouts than from stumps. Seedling densities were higher in microsites opened by logging, while root and stem sprouts were equally common across microsites. Given their abundance and the fact that root and stem sprouts at least initially grew faster than true seedlings, we conclude that vegetative regeneration in this tropical dry forest is an important mode of post-logging regeneration especially for species that regenerate poorly from seed. Resprout management should be considered as a potentially effective strategy for the procurement of regeneration following logging, especially for species that do not readily recruit from seed.     

Comparisons between generalized and specific tree biomass functions as applied to tropical ash (Fraxinus uhdei)

Allometric equations were generatedby harvesting tropical ash (Fraxinus uhdei(Wenzig) Lingelsh) trees growing on organic uplandssoils in the island of Hawaii. One of these equationswas used to estimate aboveground biomass of ten maturestands in the same area. Results indicated that theequation developed in situ, equations for white ash(Fraxinus americana L.), and generalizedfunctions for temperate and tropical forests, providedrelatively similar biomass estimates. Averagedifferences between biomass estimates from the testedequations (excluding the one for moist tropicalforests) and the function generated in situ rangedfrom 10 to 24%. One of the equations for white ashhad the lowest sum of residuals followed by thegeneralized equation for temperate forests. Theresults suggested commonality among biomass estimatesand, therefore, among relationships between treedimensions probably because most of the abovegroundtree biomass is in stem and branches, and thesecompartments are more stable than foliage mass. Equations to estimate commercial biomass and leaf areaof tropical ash are also provided.     

Toward improved understanding of the cell-wall density and porosity of wood determined by gas pycnometry

The main objective of this study was to evaluate the effect of sample preparation on cell-wall density and porosity using gas pycnometry. Native and thermally modified twin samples of Norway spruce (Picea abies (L.) Karst.), sycamore maple (Acer pseudoplatanus L.), and European ash (Fraxinus excelsior L.) were analyzed. The samples differed in terms of shape, geometry, and climatic state. On the one hand, the samples were oven dry as usual and, on the other hand, conditioned at 22 °C and 95 % relative humidity. Furthermore, the samples were processed using solvent exchange drying. In addition to helium, nitrogen was used as a displacement gas. The tests show i.a. how this can lead to misinterpretation of the cell-wall density or porosity of wood determined by gas pycnometry. The results show that native spruce has a lower cell-wall density and higher porosity compared with native maple and ash. Due to thermal modification, the cell-wall densities are decreased. The investigations show that the determined cell-wall density and porosity of the wood are strongly dependent on the sample geometry and climatic state. The cell-wall densities of all investigated wood species in the conditioned state at 22 °C and 95 % relative humidity are significantly higher compared with the oven-dry cell-wall densities.