Endangered lowland oak forest steppe remnants keep unique bird species richness in Central Hungary

The biodiversity of natural or semi-natural native,old oak woodlands have high conservation impor-tance,especially in landscapes of monocultural forest plan-tations and arable fields.With a wider variety of microhabi-tats and foraging sources,such old oak forests can provide essential habitat for native forest bird communities.We con-ducted a study using bird point counts to compare the forest bird communities of old pedunculate oak (Quercus robur)remnants with native and non-native plantations in central Hungary in a landscape of mostly arable fields,settlements,and monocultural plantations.Avian surveys were carried out in old oak forest remnants,middle-aged oak,white pop-lar (Populus alba),hybrid poplar (Populus × euramericana),black locust (Robinia pseudoacacia),and pine (Pinus spp.)plantations.Fieldwork has been carried out in nine study sites,where all six habitat types were represented (with a few exceptions),to determine total abundance,species rich-ness,Shannon-Wiener diversity,species evenness,domi-nant and indicator species,and guild abundances.We found that old oak forest remnants were the most diverse habitats among the studied forest types,while hybrid poplar and pine plantations exhibited the lowest avian biodiversity.The avian guilds most sensitive to the loss of old oak forest remnants were ground foragers,bark foragers,cavity-nest-ers,residents,and Mediterranean migratory birds.Native habitats were more diverse than non-native plantations.Our results suggest that it is important to conserve all remaining high biodiversity old oak stands and to avoid clear-cutting of monocultural plantations in favour of practices such as mixed-species plantations,longer rotation lengths,or reten-tion forestry.     

Quantitative study of poplar plantations in three Iranian provinces

Fast growing poplar species enjoy a highly favored position in Iran＇s forest product industries. Howeve~ information on poplar plantations, such as areas, growing stock and harvest volumes, are largely obtained by now scientific means and poorly executed methods. A few studies have been conducted to obtain data on the capacit,. of poplar plantations, their extent, existing growing stock, distribution and species choice in three provinces, i.e. Western Azerbaijan, Kurdistan and Hamedan, with relatively well developed management systems. We opted for cluster method, a standard sampling method for conducting similar investigations, consisting of two phases. In the firs phase we collected library information and conducted half-open interviews with villagers. In the second phase fiel~ measurements in the villages of these three provinces were carried out. Information from field measurements on growin! stock, cultivated areas, dominant species were used to estimate volumes by way of volume and weight tables. Result~ obtained from the present study indicate that the average annual volume of timber harvested in the three province~ was 697,723 m~, with an average sampling error of 22.7 per cent. This annual volume of poplar timber harvested fron the three provinces was estimated to amount to about 25 per cent of overall harvest; at that rate, the overall annu~ utilization potential of poplar plantations will be 10 million m3, which constitutes a reliable resource of raw timber for us~ in wood and paper industries.     

A decade of grey squirrel bark-stripping damage to beech in Lady Park Wood, UK

The scale and distribution of American grey squirrel (Sciuruscarolinensis) bark-stripping damage to beech (Fagus sylvatica)stems was monitored in a mixed broadleaved woodland retainedas a Research Natural Area through the use of permanent transects.During an initial outbreak of debarking damage in 1983 almostone-third of beech individuals 4 cm d.b.h. in stands of 40 years'growth were badly damaged and by 1993 this level of damage hadrisen dramatically to over 50 per cent. One-third of badly damagedindividuals in 1983, including a number of potential canopydominants, died during the decade, but some that survived grewvery vigorously. Throughout squirrels preferentially debarkedintermediate sized (10–25 cm d.b.h.) stems in particularparts of the stands aged 40–50 years, apparently tendingto select stems that were growing rapidly. Other species andstand areas of <100 years' growth remained largely unscathed.Within the 10-year period squirrels had critically affectedthe successional development of the wood.     

Towards practices favourable to plant diversity in hybrid poplar plantations

Much research effort is being devoted to developing forest management practices with limited impacts on biodiversity. While the impact of poplar Populus sp. plantations on biodiversity is relatively well-known at the landscape scale, the impact of alternative management practices at the plantation scale has received much less attention. Yet biodiversity is likely to be impacted by the choice of the poplar clone, stem density at plantation, type and duration of the understory control, and age at which the poplars are harvested. In this study, we investigated the impact of these factors on herbaceous plant communities with data from plant surveys conducted in 85 young (2–5 years) and 96 mature (11–17 years) hybrid poplar high-forest plantations in northern France. On average, ruderal or generalist plants contributed to 40.5% of the plot species richness; tall herbs (60.2%), forest (26%) and meadow plants (13.8%) contributed to the remaining 59.5% more specialised species. Soil moisture and soil nitrogen were major determinants of plant communities: wet soils were favourable to tall herbs, while meadow and forest species preferred moist soils; a significantly lower diversity of the three species groups was reported in the nutrient richer soils (in mature plantations only for forest plants). Mean species richness decreased with plantation age except for forest species. Plant communities in young plantations showed little differences in composition according to the type of understory control (chemical, mechanical or both). The development of a shrubby layer in mature plantations was restricted to the drier soils and was detrimental to both meadow plants and tall herb species. Effects of previous land use on forest and tall herb species were found only in young plantations, suggesting a rapid reset of plant communities for these two groups. This may not be the case for meadow species as the influence of previous land use was significant in mature plantations only. Finally, clone type and stem density at plantation had no significant impact on plant communities. Adjusting age at which the poplars are harvested seems the only effective way to drive plant communities in high-forest poplar plantations: delaying poplar harvest (probably beyond 15–20 years) would benefit forest plants, while advancing poplar harvest (about 10 years) would benefit tall herbs, especially in wet soil conditions.     

Species-specific biomass allometric models and expansion factors for indigenous and planted forests of the Mozambique highlands

Secondary Miombo woodlands and forest plantations occupy increasing areas in Mozambique, the former due to anthropogenic activities. Plantations, mainly species of Eucalyptus and Pinus, are being established on sites previously covered by secondary Miombo woodlands. This affects the evolution, cycle and spatiotemporal patterns of carbon(C) storage and stocks in forest ecosystems. The estimation of C storage, which is indispensable for formulating climate change policies on sequestrating CO_2, requires tools such as biomass models and biomass conversion and expansion factors(BCEF). In Mozambique, these tools are needed for both indigenous forests and plantations. The objective of this study is to fit species-specific allometric biomass models and BCEF for exotic and indigenous tree species. To incorporate efficient inter-species variability, biomass equations were fitted using nonlinear mixed-effects models. All tree component biomass models had good predictability; however, better predictive accuracy and ability was observed for the 2-predictors biomass model with tree height as a second predictor. The majority of the variability in BCEF was explained by the variation in tree species. Miombo species had larger crown biomass per unit of stem diameter and stored larger amounts of biomass per stem volume. However, due to relatively rapid growth, larger stem diameters, heights, and stand density, the plantations stored more biomass per tree and per unit area.     

Carabid species responses to hybrid poplar plantations in floodplains in France

Hybrid poplar plantations have become an important component of forest and agricultural landscapes in alluvial floodplains since poplars are among the fastest-growing trees in temperate regions. However, these habitats are thought to decrease biodiversity, including ground beetle diversity, as compared to other traditional land-uses such as grasslands and semi-natural forests. To evaluate the impacts of poplar plantations on carabid diversity, we tested whether carabid assemblages are more affected by land-use type than by canopy cover type in three alluvial floodplains in North-Eastern France. We stratified our 63-plot sampling design according to four habitat types based on land-use and plantation age. Non-metric multidimensional scaling revealed a successional gradient in species composition related to canopy cover progressing from grasslands through young, then adult poplar plantations, to semi-natural forests. Species-level response models showed that many carabid species distinguished the open habitats (grasslands and young poplar plantations) from the closed ones (adult poplar plantations and semi-natural forests). Only a few species preferred one of the traditional land-uses such as grasslands or semi-natural forests. Based on our data, the deleterious effect of poplar plantations on the conservation of ground beetles may not be as high as expected.     

Differential effects of vegetation restoration in Mediterranean abandoned cropland by secondary succession and pine plantations on bird assemblages

Two contrasting trajectories for vegetation restoration in agricultural landscapes are secondary succession following cropland abandonment that can regenerate woodlands (passive restoration) and conversion of cropland to tree plantations (active restoration), which have mostly focused on pine species in the Mediterranean Basin. We compared the effects of these two contrasting trajectories of vegetation restoration on bird assemblages in central Spain. Vegetation structure differed in the two restoration trajectories, pine plantations attaining higher tree cover and height (31% and 4.1 m, respectively) but lower strata complexity than secondary shrubland and holm oak woodland (which attained 10% and 1.4 m of tree cover and height, respectively). Bird species richness differed in stands under active or passive restoration trajectories, the former collecting a higher total number of species (4.2 species per 0.78 ha plot) than the latter (3.5 species per plot). The number of forest species increased with vegetation maturity in both restoration trajectories, but especially in stands under active restoration. The occurrence of woodland generalist species increased and of species inhabiting open habitats decreased in actively restored stands, being some of these latter species of high conservation priority in the European context but relatively common at the regional level. Bird species inhabiting pine plantations had broader habitat breadth at the regional level than those inhabiting secondary shrublands and woodlands. Maximum regional density did not differ between both restoration trajectories, but it increased with development of the herbaceous layer only at the secondary succession trajectory. The relative importance of species of European biogeographic origin was higher in mature pine plantations (58.9% of total bird abundance) than in mature holm oak woodlands (34.4%), whereas that of Mediterranean species was considerably higher in the latter (40.1%) than in the former (20%). Bird assemblages of relatively small patches of pine plantations are unable to reflect the regional avifauna, in contrast with the relationships between local and regional assemblage characteristics that can be found in isolated natural forests. We conclude that programs of vegetation restoration should base upon a range of approaches that include passive restoration, active restoration with a variety of tree and shrub species, and mixed models to conciliate agricultural production, vegetation restoration and conservation of target species.     

DAMAGE CAUSED BY SQUIRRELS IN FORESTRY COMMISSION AREAS, 1954-6

The paper examines the replies received from foresters of theForestry Commissionto questionnaires sent out at the author'ssuggestion in 1954, 1955, and 1956 on the damage caused to ForestryCommission woodlands by the two squirrels, Sciurus carolinensisand S. vulgaris leucourus, during the forest years 1954–6.The inquiry was primarily concerned with S. carolinensis, thegrey squirrel, for the killing of which rewards have been offeredsince 1953, ut, for 1955 and 1956, information was sought alsoabout the red squirrel. The most serious economic damage doneby both squirrels is considered to be the stripping of barkfrom the stemsof growing trees and it is this damage which isexamined. The information received is sifted critically andthe results summarized in thirteen tables andin two diagrams.     

伐根嫁接杨树林根系分布特征

通过对比研究大兴区的伐根嫁接杨树林分和与其地下和地上部分分别相同的植苗造林杨树林分,得出伐根嫁接杨树林根系的特殊分布特征。采用全挖法获取杨树总根量和根型,采用土柱法获取吸收根(细根≤2mm,粗根210mm)。结果表明:伐根嫁接林根系总干重分别是相同地下和地上部分植苗造林的1.83倍和7.38倍;其根系数量多且粗壮,为水平斜生根型,而植苗造林林分为水平根型;伐根嫁接林总细根量和总粗根量分别比两个植苗造林林分提高了86.27%和224.65%,59.06%和65.86%;与植苗造林相比,伐根嫁接林表层的吸收根垂直和水平分布都表现异常,垂直分布中0～10cm土层的细根分布较多,10～20cm土层的分布较少;水平分布中株间0～20cm土层的分布异常多。该结论为伐根嫁接杨树林的生长优势提供了进一步的微观解释。     

The Effect on Beech of Bark-Stripping by Grey Squirrels

In 1979 a survey of beech trees in the Chiltern hills was carriedout to establish the extent of damage caused to trees by greysquirrels. The frequency of attack by grey squirrels was greatestaround the age of 40 years and was concentrated on the basesof the trees. Although the wounds were more liable to becomestained or decayed the longer they remained open, a very highproportion of them (80% +) were not stained or decayed morethan four annual ring into the tree. Callus growth followingwounding was generally dependent on the age of the tree, beingpoor in older trees, but it also tended to be greater with biggerwounds.     

Hybrid poplar plantations in a floodplain have balanced impacts on farmland and woodland birds

Hybrid poplar plantations are increasing worldwide and are often accused of impoverishing bird communities. We conducted 124 bird point counts in a landscape where plantations, semi-natural forests and farmland occupied similar surface areas. As expected, birds occurred at higher densities in areas dominated by forests than dominated by plantations, mostly due to the scarcity of late-successional forest birds in plantations. Contrary to expectations, bird communities were the poorest in farmland dominated areas and the most specialised in areas dominated by young plantations. Indeed, many grassland species, including some of conservation concern in Europe, frequently used young plantations. However, plantations have probably depleted grassland bird communities by fragmenting open areas, while playing a limited positive role on forest species. Total length of unpaved roads had a positive effect on community specialisation index, while total length of paved roads and mean forest/plantation patch size played no role. Bird density increased with the development of the understory vegetation in mature poplar plantations. We conclude that poplar should not be planted at the expense of areas of high conservation value; in other cases, they may increase the overall diversity of bird communities. At the plantation scale, we advocate stopping understory removal as soon as possible and maintaining old trees and hedgerows alongside or within plantations to provide suitable breeding habitats for bird species that may be foraging in the plantations.     

马鞍山江滩3个杨树无性系的生长比较

对安徽省马鞍山市长江滩地8年生的Ⅰ-72、Ⅰ-69和中林46计3种杨树无性系混交林进行了调查。结果表明,中林46杨的胸径、树高和材积生长量均明显小于Ⅰ-72杨和Ⅰ-69杨。8年生的中林46杨平均材积只有0.199m3/株,Ⅰ-72杨和Ⅰ-69杨的平均材积分别是0.499 m3/株和0.360 m3/株。Ⅰ-72杨的胸径明显大于Ⅰ-69杨,但树高差异很小。就以上3种杨树无性系而言,中林46杨不宜在长江滩地上进行造林;Ⅰ-72杨和Ⅰ-69杨较适宜,尤其是在大株行距造林中,采用Ⅰ-72杨则更容易培育大径材。     

Some Key Issues Concerning Current Poplar Production and Future Marketing in the United Kingdom

This paper presents survey evidence concerning the UK poplar (Populus spp.) plantation with particular emphasis applied to production systems, markets, and trends. Our results are based on primary data and information that were sourced from a survey of poplar growers in summer 2000. The results show a growing interest in planting poplars throughout the 1990s. Between 1989 and 1998, poplar plantations were established mainly on land previously used for arable purposes and pastureland, and to a lesser extent, on other lands. Growers perceive that a robust value-added market for poplar products may be developed providing poplar cultivars are properly managed. The most common interamericana clones planted are the varieties Beaupré and Boelare. Specifically, plantation sites are currently using the polyclonal system and are growing on sites that have a diversity (mixture) of other forest species. Loss of resistance to disease organisms (e.g., rust fungi of the genus Melampsora) appears to be one of the main current threats to successful poplar exploitation.     

Carbon pools and sequestration in forest ecosystems in Britain

British vegetation is estimated to contain 113.8 million tC,80 per cent of which is in forests and woodlands (91.9 milliontC). Sitka spruce plantations, although covering 21.4 per centof the forest/woodland area, contain only 8.2 per cent of theforest/woodland carbon, because the plantations are young andhave an average of only 14.1 tC ha^–1. Broadleaved woodlandsin Britain have an average of 61.9 tC ha^–1 and contain46.8 per cent of the total carbon in all vegetation. A breakdownis given of the carbon density (tC ha^–1) and content ofdifferent tree species. A carbon density map of Britain highlightsthe concentration of carbon in the broadleaved woodlands insouthern England and in the large conifer plantations in southernScotland and northern England. Carbon storage in the trees, products, litter and soil can beevaluated in terms of long-term equilibrium storage or short-termrate of storage. These two components vary among forest typesin Britain and globally. Plantations harvested at the time ofmaximum mean annual increment (MAI) will not store as much carbonas mature, old-growth forests on the same site unless they havelong-lasting products and/or are very fast growing. Maximumequilibrium carbon storage is generally achieved by harvestingat the time of maximum MAI when the lifetime of products exceedsthe time to maximum MAI. Undisturbed peatlands sequester CO₂and emit CH₄, and may be greenhouse neutral. When peatlandsare drained and planted with trees, they stop emitting CH₄ andstore carbon in the trees, forest litter, forest soil and woodproducts. However, these greenhouse gas ‘gains’are offset by the oxidation to CO₂ of the peat, and the gainsare exceeded by CO₂ losses when 20–40 cm depth of peathas been oxidized. Forests in Britain are currently sequestering1.5–1.7 million tC a^–1 in trees, 0.3–0.5 tCa^–1 in litter and 0.5 million tC a^–1 in wood products,totalling about 2.5 million tC, equivalent to about 1.5 percent of the carbon currently emitted by burning fossil fuelsin the UK. In order to maintain the current forest carbon sink,the forest area needs to continue to expand at about 25 000ha a^–1 of upland conifers or 10 000 ha a^–1 of poplarson good land.     

杨树低产林成因及对策——以宿州市踊桥区祁县镇为例

通过设立固定标准地对杨树的中幼林龄期和近熟林龄期生长情况进行调查分析，了解踊桥区祁县镇不同立地条件下杨树长势，判断林分立地条件对生长量影响的关键因子，并进行了标准地土壤剖面结构、理化性质和土壤养分含量对比，结论如下：影响杨树生长的关键因素是林地土层厚度，分析了杨树低产林形成原因是：土壤层浅、瘠薄、空隙度小、质地粘重。并提出相应对策：杨树低产林改造；加强中幼林抚育、进行土壤改良；发展林下经济改善土壤结构理化性质；营造复层林、间接改良土壤，提高林地综合利用率。     

Tree growth and nutrient status of soil in a poplar (<Emphasis Type="Italic">Populus deltoides</Emphasis> Bartr.)-based agroforestry system in Punjab,India

Poplar (Populus deltoides Bartr.) based agroforestry systems are economically viable and more sustainable than many other crop rotations prevalent in northern India. Growth {girth at breast height (GBH) and height} and productivity (volume) of clone G-48 of poplar spaced at 5 x 4 m, soil organic carbon (OC), and concentration of available macronutrients (N, P and K) and micronutrients (Zn, Fe, Mn and Cu) in surface soil (0-15 cm depth) were determined at an interval of six months starting from April 2002 till October 2003 in one and four year old (in January 2002) 16 poplar plantations on farmers' fields in Ludhiana, Punjab. The observations were taken from plantations having fodder {sorghum (Sorghum bicolor)/pearlmillet (Pennisetum americanum) in summer}-wheat (Triticum aestivum) (in winter) rotation throughout the poplar age and those having sugarcane (Sachharum officinarum) initially during two years and fodder-wheat rotation thereafter. The GBH, height and volume of younger plantations intercropped with fodder-wheat rotation were 15.6, 17.2 and 46.7%, respectively higher than that of plantations intercropped with sugarcane. Growth increment of poplar was markedly higher during April to October than October to April. Soil OC was significantly greater in older (6.83 g kg-1) than the younger (5.35 g kg-1) plantations. Available macronutrients in soil increased at successive sampling times. The average Zn concentration at final sampling was 17% lower compared to initial sampling, whereas the other micronutrients tended to increase during April 2002 to October 2003 and the increase was higher in four year old plantations than one year due to higher inputs of organic matter.     

集约经营杨树人工林中光肩星天牛不成灾原因的探讨

光肩星天牛Ａｎｏｐｌｏｐｈｏｒａｇｌａｂｒｉｐｅｎｎｉｓ，（Ｍｏｔｓｃｈｕｌｓｋｙ）分布于国内大部分省区。山东绝大多数个体（约占９０％）１年１代，少量个体（约占１０％）３年２代（即１年１代和２年１代交替进行），以卵、卵态幼虫和幼虫越冬。成虫有啃食嫩枝...     

Do mature pine plantations resemble deciduous natural forests regarding understory plant diversity and canopy structure in historically modified landscapes?

We compared the structure of the arboreal layer and the diversity and species composition of the understory vegetation of three types of mature forest communities: oak (Quercus pyrenaica) and beech (Fagus sylvatica) forests and Scots pine (Pinus sylvestris) plantations. Our main aim was to determine whether differences in these variables existed and were due to the identity of the dominant tree species. We selected four stands or replicates per forest type located geographically close and with relatively similar conditions. We found no differences in the arboreal structure of oak and beech forests, which were characterised by great variability in tree size, while in case of plantations, this variability was lower at both the intra-stand (estimated by the coefficient of variation) and inter-stand (i.e. the four replicates harboured trees of similar sizes) scales. However, the highest variability in the canopy layer of natural forests was not consistently linked to greater understory species richness. Indeed, the lowest plant species richness was found in beech forests, while oak forests harboured the highest value at either the sampling unit (per m²) or stand scales. The greatest negative correlation between plant diversity and the environmental variables measured was found for litter depth, which was the highest in beech forests. The results obtained by the CCA indicated that the four replicates of each forest type clustered together, due to the presence of characteristic species. We concluded that pine plantations did not approach the environmental conditions of native forests, as plantations were characterised by singular understory species composition and low arboreal layer variability, compared to natural woodlands.     

Growth and provenance of Norway maple (Acer platanoides) in lowland Britain

The results of an experiment to investigate the early growthand form of ten different provenances of Norway maple (Acerplatanoides L.) are described. Two sites were planted and after8 years survival was 88 per cent and 95 per cent and heightincrement was 402 cm and 201 cm; confirmmg the potential ofNorway maple to be a productive forest tree. Provenances thatperformed well were from Germany, the Netherlands, Denmark andYugoslavia; exact locations were not known for all seed collections.A provenance from Russia was included, material from this fareast has rarely been tested in Britain. However, as expected,its performance was relatively poor. The main constraint tofurther planting of Norway maple is the palatability of thebark to grey squirrels (Sciurus carolinensis Gmelin.). However,it is a useful tree for high pH and heavy soils and as an alternativespecies to sycamore (Acer pseudoplatanus L.).