Are endoparasites of common shrews (<Emphasis Type="Italic">Sorex araneus</Emphasis>) sensitive to tree species conversion in sub-Arctic birch forests?

Shrews (Soricomorpha) are among the most numerous small forest dwelling mammals in boreal forests ecosystems. In Norway large areas of sub-Arctic birch (Betula pubescens) forests have gradually been replaced by non-native spruce (Picea abies) plantations during the last century. This conversion has led to changes in forest floor vegetation and soil conditions which negatively influence invertebrates serving as prey for shrews and intermediate hosts for shrew endoparasites (helminths). In this trapping study we assessed if abundance and individual condition of common shrews (Sorex araneus) and prevalence and species richness of associated helminths, responded to spruce plantations in a manner that could indicate community level changes. Shrews colonized plantations in autumn, but never attained abundances comparable to the birch forest types. Shrews in plantations had lower body mass compared to those trapped in the birch forests. We identified 15 helminth species, and detected large differences in prevalence. Only one common helminth had significantly higher prevalence in the birch forest. By analysing prevalence of all species jointly, the highest prevalence was in moist birch forests and lowest in spruce plantations. Species richness estimates were lower in plantations, however not statistically significant. Although prevalence and species richness of helminths in common shrews were affected by tree species conversion, we judge the responses to be too weak and uncertain and the sampling and analysis too laborious to make shrew endoparasites suitable for monitoring purposes. However, monitoring abundance of common shrews is likely an efficient way of detecting changes in the forest floor fauna resulting from modern forestry practices.     

Establishment and early growth of introduced indigenous tree species in typical plantations and shrubland in South China

Unsuccessful colonization by indigenous tree species into established plantations has retarded the succession of artificial plantations to more natural, secondary forests in South China. To understand how to improve colonization by seedlings of indigenous species, we determined how performance of indigenous seedlings is affected by seedling species (the shade-intolerant Castanopsis chinensis, the moderately shade-intolerant Michelia chapensis, and the shade-tolerant Psychotria rubra), the site into which the seedlings were transplanted (a mixed-legume plantation, a eucalyptus plantation, a mixed-native plantation, a mixed-conifer plantation, and a shrubland), and site preparation (removal or retention of understory vegetation and litter). Seedling survival and growth were generally increased by removal of understory vegetation and litter. C. chinensis and M. chapensis grew better in the mixed-legume and mixed-conifer plantations, while P. rubra grew better in mixed-native and mixed-conifer plantations. Responses of the transplanted seedlings to environmental factors were species specific. The effects of light on seedling survival and growth were correlated with the shade tolerance of the species. Soil moisture was important; it was positively correlated with survival but negatively correlated with growth of C. chinensis seedlings. Growth of C. chinensis and M. chapensis was positively correlated with soil potassium, while growth of P. rubra was positively correlated with soil organic matter but negatively correlated with soil hydrolyzed nitrogen. These findings suggest that we should select suitable native species under the different plantations before improvement of plantations. Light and soil moisture are most important environmental factors for the selection of species specific. Site preparation and fertilizer are needed during the improvement of those plantations.     

The changes of understory plant diversity in continuous cropping system of <Emphasis Type="Italic">Eucalyptus</Emphasis> plantations,South China

The assessment of biodiversity in managed plantations has become an important issue for long-term sustainability of the ecosystem. The continuous cropping system (CCS) is common practice in Eucalyptus plantations in southern China. In order to clarify the effects of such a practice on species compositions, species diversity, and functional type compositions of understory vegetation, a field trial was installed in the first and second rotations of Eucalyptus plantations. The treatments were replicated three times and arranged in a simple completely randomized design. Vegetation surveys were performed in 1998–2005 following the treatments. Although the CCS had no significant effect on the composition structures in terms of life-form, growth-form, seed dispersal strategies and breeding strategies, there were significant differences in percent coverages of shrub (SLC) and herbaceous layer (HLC) between two types of stand. The CCS reduced the species richness and species diversity remarkably, and was also particularly favorable for r-strategy herbaceous species at the expense of k-strategy woody species in understory vegetation. The repeated disturbances to soil and vegetation including clear-cutting followed by prescribed burning and mechanical plowing maybe the main factor which results in the negative change of understory plant diversity. Although more comprehensive studies on disturbance and a long-term monitoring of a broad-scale project will be required, we suggest that alternative silviculture, consisting of practices other than clear-cutting and prescribed burning, should be introduced to conserve species composition and diversity of Eucalyptus plantations.     

Important insect pests of poplars in agroforestry and strategies for their management in northwestern India

Today, more than 143 species of insects infest both indigenous as well as exotic species of poplars in northwestern India, with about 65 species infesting Populus deltoides alone. Random sampling surveys (1984-2002) were undertaken in lower hills and plains of six states (Uttar Pradesh, Uttaranchal, Haryana, Punjab, Himachal Pradesh, and Jammu and Kashmir) in this region. The survey included 36 nurseries, 84 large ( ≥ 3 ha) and 255 small (< 3 ha) block and bund plantations and recorded seven species causing outbreaks. However, eight insects having wide spread distribution in this region were identified as posing a threat to agroforestry with P. deltoides and need to be managed. Amongst these, three species (Clostera cupreata, C. fulgurita and Apriona cinerea) were ranked as 'major pests' as they had relatively higher incidence (> 50% of attack) and caused extensive economic loss during outbreaks, coupled with tree mortality which persisted for several years in succession over large areas. Five insects were identified as 'potential pests', as they also caused heavy infestation and economic loss, but only in some years, on a localized scale and with no large scale plant mortality, but need to be checked to improve productivity. The 'potential pests' were: one species in plantations (Ascotis selenaria) and four insects in nurseries [(Eucosma glaciata , Phalantha phalantha, Nodostoma waterhousie and white grubs) with >50% incidence]. Integrated pest management practices, comprising cultural methods, use of bio-pesticides, tolerant poplar varieties/clones, natural enemies, recommended safe insecticides and avoiding alternate host plants of the pest, are discussed for important pests.     

Carbon storage in biomass,litter, and soil of different native and introduced fast-growing tree plantations in the South Caspian Sea

Replantation of degraded forest using rapidgrowth trees can play a significant role in global carbon budget by storing large quantities of carbon in live biomass,forest floor,and soil organic matter.We assessed the potential of 20-year old stands of three rapid-growth tree species,including Alnus subcordata,Populus deltoides and Taxodium distichum,for carbon(C) storage at ecosystem level.In September 2013,48 replicate plots(16 m × 16 m) in 8 stands of three plantations were established.36 trees were felled down and fresh biomass of different components was weighed in the field.Biomass equations were fitted using data based on the 36 felled trees.The biomass of understory vegetation and litter were measured by harvesting all the components.The C fraction of understory,litter,and soil were measured.The ecosystem C storage was as follows: A.subcordata(626.5 Mg ha~(-1)) [ P.deltoides(542.9Mg ha~(-1)) [ T.distichum(486.8 Mg ha~(-1))(P \ 0.001),of which78.1–87.4% was in the soil.P.deltoides plantation reached the highest tree biomass(206.6 Mg ha~(-1)),followed by A.subcordata(134.5 Mg ha~(-1)) and T.distichum(123.3 Mg ha~(-1)).The highest soil C was stored in theplantation of A.subcordata(555.5 Mg ha~(-1)).The C storage and sequestration of the plantations after 20 years were considerable(25–30 Mg ha~(-1) year~(-1)) and broadleaves species had higher potential.Native species had a higher soil C storage while the potential of introduced species for live biomass production was higher.     

Biomass production physiology and soil carbon dynamics in short-rotation-grown Populus deltoides and P. deltoides × P. nigra hybrids

Fast-growing woody species grown in dense, short-rotation plantations on land previously in agriculture offer potential economic benefits in products such as engineered construction material, boiler fuel, non-food-based biofuel feed stocks and other carbon (C)-based products and credits. However, information on the effects on major C pools of short-rotation culture is relatively sparse. In this study, Populus deltoides and P. deltoides × P. nigra hybrid clones were grown for 5 years at 1 m × 1 m spacing in plantations on a former pasture of high native fertility in the Missouri River floodplain in the lower Midwest U.S.A. Above- and below-ground biomass production, leaf area-based production efficiency, photosynthetic attributes and soil C dynamics were studied.     

Growth analysis of the competition–density effect in non-self-thinning Populus deltoides and Populus?×?euramericana plantations

The competition–density (C–D) effect for non-self-thinning Populus deltoides and Populus × euramericana plantations from 3 to 9 years was analyzed using the reciprocal equation of the C–D effect. The C–D effect was well described by the reciprocal equation, and with the progress of time the C–D curve, on logarithmic coordinates, of the P. × euramericana plantations shifted upward faster than that of the P. deltoides plantations. With increasing physical time t, the biological time τ, i.e. the integral from zero to t of the coefficient of growth λ(t) in the general logistic curve with respect to t, increased rapidly during early growth stages and the increases in τ gradually became slow during later growth stages. This trend was more evident in the P. deltoides plantations than in the P. × euramericana plantations. The coefficients A and B included in the reciprocal equation were calculated at each growth stage. With increasing τ, the coefficient A, the reciprocal of which means the asymptote of yield (=wρ) at a given growth stage, increased abruptly to a maximum value and then tended to decrease gradually to a constant level. On the other hand, the coefficient B, the reciprocal of which means the asymptote of mean stem volume at a given growth stage, decreased exponentially and tended to be close to zero with increasing τ. The λ(t) decreased with increasing stand age, whereas the final yield Y(t) defined as W(t) ρ, where W(t) is the asymptote of w in the general logistic growth curve, increased gradually with increasing stand age. The differences in coefficients A, B, and λ(t) between the two species were reported.     

Factors influencing establishment by direct seeding of indigenous tree species in typical plantations and shrubland in South China

Seed limitation of desired indigenous species has constrained the succession of established plantations from an early successional stage, to more natural forests in South China. Because of its low cost and time-saving advantages, direct seeding has been considered a useful method in forest regeneration. To improve our understanding of whether and how direct seeding can lead to the establishment of indigenous tree species, we carried out an experiment in four typical plantations (eucalyptus, mixed-native, mixed-legume, mixed-conifer) and a shrubland in South China. We also tested the effect of understory vegetation and litter removal on seedling establishment and growth. Seeds of three indigenous tree species (Castanopsis chinensis, Cryptocarya chinensis, and Psychotria rubra) were sown with understory vegetation and litter either retained or removed. Seedling emergence, survival, and growth were recorded for 21 months. We found that conditions that favored seedling emergence often differed from those that favored seedling survival. While the removal of understory vegetation and litter did not influence the final seedling establishments for all the three introduced species, growth of Psychotria rubra was influenced at several sites. Seed mass was positively correlated with seedling emergence and subsequent growth. The large-seeded Castanopsis chinensis showed higher emergence and growth than the intermediate-seeded Cryptocarya chinensis or the small-seeded Psychotria rubra. Seedlings of Castanopsis chinensis grew better in plant communities with high understory light penetration and high soil exchangeable potassium. Growth of P. rubra seedlings decreased significantly with soil hydrolyzed nitrogen. In conclusion, direct seeding can be useful for the establishment of indigenous tree species into plantations and shrubland. Optimizing early seedling establishment and growth will require the selection of suitable native species for improving seedling establishment in different plantations. Additionally, understory vegetation and litter and fertilizer should be properly managed to enhance the establishment of certain indigenous tree species.     

Pattern and Composition of Secondary Succession Beneath Caribbean Pine Plantations of Southwest Sri Lanka

This study examined the vegetation growing beneath Caribbean pine (Pinus caribaea) plantations established within previously abandoned tea lands adjacent to intact rain forest in southwest Sri Lanka. To examine the pattern and composition of secondary succession and factors affecting it, vegetation was sampled in different relative locations (interior and edge conditions) within plantations. Results demonstrated that more vegetation was found near the plantation edges than in the interior, and this pattern was prominent for both wind- and bird- dispersed species. The vegetation represented a mixture of species belonging to a range of successional guilds representing early (17 species, 42.4% in stem count) and late-successional species (52 species, 40.6%), although native long-lived canopy tree species were mostly absent. Bird-dispersed species dominated the flora (80 species, 86.7% in stem count). Abundance of an exotic shrub Clidemia hirta (Melastomataceae) showed a negative correlation with that of other species, indicating its impact on native flora. Underplanting of native canopy species may be effective in assisting secondary succession and control C. hirta in the plantations.     

Faunal use of bluegum ( Eucalyptus globulus ) plantations in southwestern Australia

We examined the faunal use of Eucalyptus globulus plantations in southern Western Australia, and compared use of remnant vegetation, agricultural land and plantations in different positions relative to large tracts of remnant vegetation. In general, faunal use of plantations is less than in comparison with adjacent remnant vegetation, but more than in open pasture. For all faunal groups there were almost twice as many species recorded in the native vegetation than in any site in the plantations or on agricultural land and they were in greater abundance. Faunal use of plantation edges and interiors did not show consistent patterns. Generally, edges next to remnants were most frequently used, but individual species showed a wide range of patterns of use across the various habitat types studied. More species of bird identified as being “at risk” were found in plantation edges than in interiors. Adjacency to remnant vegetation increased plantation use by some species, but the overall differences between isolated plantations and those adjacent to remnant vegetation were relatively small. We conclude that plantations provide some value in terms of habitat for some species, including some of conservation concern, but that this value is limited by the lack of habitat complexity in the intensively-managed plantations. This revised version was published online in June 2006 with corrections to the Cover Date.     

Understory plant diversity assessment of <Emphasis Type="Italic">Eucalyptus</Emphasis> plantations over three vegetation types in Yunnan,China

Biodiversity in managed plantations has become an important issue for long-term sustainability of ecosystems. The environmental effects of plantations comprised of fast-growing introduced trees have been vigorously debated. On one hand, monocultures have been said to exhaust resources, resulting in decreased biodiversity. Conversely, it has been stated that monocultures may favor regeneration of undergrowth plants from surrounding forests, increasing biodiversity. In order to clarify the effects of planting Eucalyptus trees on species composition, diversity, and functional type of understory vegetation in Yunnan province, a field trial was implemented to compare Eucalyptus plantations (EPs) with two other local current vegetation types (secondary evergreen forests (SEs), and abandoned farmlands (AFs)). Each vegetation type was sampled in each of three elevational ranges (low = 1,000–1,400 meters above sea level (masl), medium = 1,400–1,800 masl, and high = 1,800–2,200 masl). Sample sites within each elevational range had similar environmental characteristics (slope, aspect, etc.). Thus, we sampled three vegetation types at each of three sites at each of three elevations for a total of 27 plots. We calculated relative abundance and importance value of species and diversity indexes to evaluate differences among local current vegetation types and elevational ranges, employing multivariate ordination analyses and other methods such as Analyses of Variance (ANOVA) and Indicator Species Analysis. We found that fast growing introduced Eucalyptus plantations led to reduced plant diversity in the study area, and that rare or threatened species were recorded almost exclusively in the SE plots, being essentially absent from the EP and AF plots. The understory plant diversity did not correlate with the altitude gradient significantly. Eucalyptus plantations (EPs) have a simpler community structure than that of either secondary evergreen forests (SEs; similar to natural state) or abandoned farmlands (AFs). No variable significantly explained variation of the understory shrub layer, but soil moisture-holding capacity and overstory coverage were significant in explaining variation of the understory herb layer, suggesting that the study of soil physical properties is necessary for better understanding of their importance in Eucalyptus plantations and other local current vegetation types.     

黑杨派基因库内无性系生长特性的遗传分析*

黑杨派基因库内无性系生长特性的遗传分析解荷锋，于中奎，陈一山，张绮纹，徐红关键词黑杨派，基因库，生长特性，遗传变异黑杨派杨树在杨属栽培种中速生性能及经济价值最高［１］，其中尤以美洲黑杨为佳。我国从长江流域到黑龙江以南，广大平原地区都适宜生长［２］。为...     

Structure and Function of <Emphasis Type="Italic">Populus deltoides</Emphasis> Agroforestry Systems in Eastern India: 1. <Emphasis Type="Italic">Dry matter dynamics</Emphasis>

Agroforestry systems based on poplar (Populus deltoides) are becoming popular in eastern and northern parts of India. Therefore studies on the structure and function of the systems are important. The investigations included allometric equations for above- and belowground tree components, crop and plantation floor biomass and litter fall estimation at Pusa, Bihar, India. Biomass, floor litter mass, litter fall and net primary productivity (NPP) of plantations increased with an increase in age of trees whereas, crop biomass for any specific crop interplanted with poplar decreased with the age of the plantation. The total plantation biomass increased from 12.08 to 90.59 Mg ha⁻¹ and NPP varied from 5.69 to 27.9 Mg ha⁻¹ year⁻¹. The biomass accumulation ratio ranged from 2.1 to 3.2. Total annual litter fall was in between 1.95 and 10.00 Mg ha⁻¹ year⁻¹, of which 92–94% was contributed by leaf litter. Compartmental models were developed for dry matter distribution in agroforestry systems involving young (3-year-old) and mature (9-year-old) poplar trees interplanted with various crops, the crops being grown in two rotations maize (Zea mays) – wheat (Triticum aestivum) – turmeric (Curcuma domestica) and pigeonpea (Cajanus cajan) – turmeric. This study substantiates the potential of Populus deltoides G₃ under agroforestry combinations.     

Calcium accumulation in the wood of short-rotation cottonwood species: effects on pulp properties

We have found that kraft pulp handsheets, made from a number of hybrid poplar (Populus trichocarpa × Populus deltoides) clones, contain unusual surface deformations caused by vessel element mineral blockages. The blockages were composed mainly of calcium salt deposits that survived chemical pulping and beating processes. Our findings confirm that a natural process of accumulation of calcium salts occurs in certain poplar species. In this article, we describe the implications for the multi-use implementation of these poplars in short-rotation, intensive-culture plantations.     

Effects of N, NP, and NPKS fertilizers applied to four-year old hybrid poplar plantations

Mineral fertilizers were applied to adjacent plantations of 2, 4-year old, hybrid poplars: clone 27 (Northwest, P. deltoides × P. balsamifera) and 794 (Brooks, P. deltoides × P. × petrowskyana), in north eastern Alberta. Fertilization was done in May 2003 to see whether growth rates could be increased and rotations shortened. Three fertilizers (N, NP and NPKS + Cu + Zn) were applied at each of three rates (supplying N at 0, 100 and 200 kg ha⁻¹) in a factorial randomized block design to the two separate plantations. Fertilization with 200 kg ha⁻¹ N and 100 kg ha⁻¹ P increased volume growth of clone 27 by 1 m³ ha⁻¹ year⁻¹ over 2 years. Clone 794 showed no volume response to fertilization, but produced 8.7 m³ ha⁻¹ more than clone 27. Leaf area, dry mass and nutrient concentrations of both clones increased in the first year after fertilization, showing that fertilizer uptake occurred. Decrease in leaf size between 2003 and 2004 was affected by fertilizer level in clone 794. There were differences between some nutrient concentrations in the soils occupied by the two clones, and clone 794 had higher leaf concentrations of N, K, Ca, S, Mn, Zn, B and Mo than clone 27. Fertilization of 4-year old plantations of either clone was unwarranted, and planting clone 794 would be likely to provide greater yield than planting and fertilizing clone 27.     

美洲黑杨及其杂种在世界和我国杨树栽培中的地位与作用

本文介绍了美洲黑杨的天然分布, 生长状况。西欧各国对其珍贵基因资源的重视和利用, 我国引种美洲黑杨的现状及其作用等, 并对我国进一步利用美洲黑杨的基因资源, 促进我国杨树栽培的发展提出了一些看法。     

Biomass production potential of three short rotation woody crop species under varying nitrogen and water availability

A study was conducted in an agricultural field to examine the biomass production of three fast-growing short rotation woody crop (SRWC) species, Populus deltoides, Quercus pagoda, and Platanus occidentalis using fertilization and irrigation (fertigation). The study included a randomized complete block (RCB) with five treatments; control, irrigated, and irrigated with 56, 112, and 224 kg nitrogen (N) ha⁻¹ year⁻¹. We quantified survival, basal area, standing biomass, aboveground net primary productivity (ANPP), leaf area index (LAI), and growth efficiency (GE) for each species along the soil nitrogen and water gradient. P. deltoides had low rates of survival (83, 82, and 77% years six, seven, and eight, respectively), but had production values greater than Q. pagoda and P. occidentalis. Standing biomass reached its peak for P. deltoides and P. occidentalis (17.56 and 10.36 Mg ha¹, respectively) in the irrigation treatment, and in the 112 kg N treatment for Q. pagoda (5.42 Mg ha⁻¹). P. deltoides and P. occidentalis ANPP peaked in the irrigation treatment (6.66 and 6.31 Mg ha⁻¹ year⁻¹, respectively) and in the 112 kg N (4.43 Mg ha⁻¹ year⁻¹) for Q. pagoda. ANPP was correlated with LAI; however, the relationship was species specific. Maximum ANPP was reached below the maximum LAI for Q. pagoda and P. occidentalis. P. deltoides ANPP was highest at the maximum LAI, which was achieved with IRR. These results suggest that species-specific cultural practices producing optimum LAI and maximum ANPP should be identified before fertigation techniques are adopted widely for SRWC production on agricultural fields.     

Vegetation succession process induced by reforestation in erosion areas

Reforestation is one of the most important and efficient measures of water and soil conservation. Based on field investigations in the Shangyang Soil Conservation and Reforestation Station in Huizhou, Guangdong Province, China, we studied the variation in vegetation development, vegetation succession processes and soil erosion. The regional vegetation consists mainly of monsoon evergreen broad-leaved forests (MEBF). The area was deforested and became a denuded hill area with extremely high soil erosion in the 1960s and 1970s. Then, the area was closed in order to allow recovery of the vegetation. Under natural conditions the vegetation development and succession processes were slow during which soil erosion and strong sunshine and evaporation slowed down the development of the vegetation. About 25 years later, the vegetation cover was still merely 35% or so. The dominant vegetation types were heliophilous herbage and shrubs which formed a poorly developed shrub-herbage community and erosion remained high. In contrast, reforestation with selected tree species dramatically speeded up the vegetation succession process. About 12 years after reforestation, vegetation cover of the Acacia auriculiformis plantations in the Shangyang Station was 90% and erosion was under control. After 23 years, understory vegetation, consisting of indigenous species, had developed in the plantations. The planted trees and naturally developing herbage, shrubs, bamboo, local trees and liana formed a complex vegetation community in three layers. It will take 60 years for the vegetation to succeed from bare land to a secondary growth forest under natural conditions. Reforestation may speed up the vegetation succession process. The time may be reduced to 20 years. Reforestation is the most effective measure of vegetation restoration and erosion control in this area. __________ Translated from Acta Ecologica Sinica, 2006, 26(8): 2558–2565 [译自: 生态学报]     

Forage production in natural and afforested grasslands of the Pampas: ecological complementarity and management opportunities

In managed rangelands periods of low primary productivity determine troughs of forage availability, constraining animal production year-round. Although alternative tools to increase forage availability during critical seasons exists, most of them are unaffordable and short-lived in marginal areas. We explore the potential benefits of deciduous tree plantations favoring winter forage productivity by comparing aboveground net primary productivity (ANPP) patterns in herbaceous understory to tree plantations and natural grasslands in the Pampas (Argentina). These temperate subhumid grasslands are characterized by the coexistence of winter species, mainly C3 grasses of the native genera Stipa, Piptochaetium, and Bromus and the exotic genera Lolium and Festuca) and summer species (mainly C4 grasses of the native genera Paspalum, Bothriochloa, and Stenotaphrum) that replace each other throughout the seasons, with domination of the latter. We hypothesize that the natural decoupling of growing seasons between winter deciduous trees and winter grasses could provide the basis for the sustainable promotion of winter forage. We measured ANPP on two 23-year-old Populus deltoides plantations and their understory and compared them with adjacent open grasslands. Afforested stands had 55–75% higher annual ANPP than their non-afforested neighbors, with trees contributing ~70% to total ANPP. Herbaceous canopies beneath plantations achieved about half of the ANPP observed in non-afforested situations with a contrasting seasonal distribution associated with shifts from C4 to C3 grass dominance. Winter ANPP, the most critical source of forage in these grazing systems, was similar or higher in the herbaceous understory of tree plantations to that on their non-afforested counterparts, suggesting that mixed systems involving deciduous trees and understory pastures are a valid and viable option in the region.