Responses of the seedlings of five dominant tree species in Changbai Mountain to soil water stress

Soil water stress was studied on the potted seedlings of five dominant tree species (Pinus koraienes Sieb.et Zucc.,Fraxinus mandshurica Rupr., Juglans mandshurica Maxim, Tilia amurensis Rupr. and Quercus mongolica Fisch.ex Turcz) from the broadleaved/Korean pine forest in Changbai Mountain. Leaf growth, water transpiration and photosynthesis were compared for each species under three soil moisture conditions: 85%-100% (high water, CK), 65%-85% (Medium water, MW) and 45%-65% (low water, LW) of 37.4% water-holding capacity in field. The results showed that the characteristic of typical drought-resistance of the leaves is significantly developed. The net photosynthetic rate and water use efficiency of Fraxinus mandshurica were higher in MW than those in CK. But for the other four species, the net photosynthetic rate and water use efficiency in CK were lower than those in MW and LW. The transpiration rate responding to soil moistures varied from species to soecies.     

Can we really manage tropical forests without knowing the species within? Getting back to the basics of forest management through taxonomy

Considering the pressures on tropical forests from deforestation and the recent expansion of harvesting through forest concessions in the Brazilian Amazon, it is imperative that forest management systems are scrutinized to ensure sustainability. One of the basic problems in forest management is the correct identification of species within the forest stand. While this is a well known issue, little consideration is given to how to mitigate this problem or its affects on management practices and conservation. This paper examines the current practice of forest inventories in the Brazilian Amazon, as part of the mandatory system of reduced impact logging (RIL), using extensive forest inventory verification. The results show that the RIL management plan implemented in the project area was based on a highly inaccurate forest inventory. At least 132 species or 43.5% of all species identified after botanical checking did not appear in the forest inventory and the common practice of matching vernacular names to scientific ones proved to be severely deficient. In contrast, a high percentage of field identifications based on local people's expertise were correct. We suggest changes to current practices, including the training and use of parataxonomists, the collection of samples for verification, and stricter government control over current practices, which will achieve greater accuracy in data collection and forest management planning. Ultimately, we argue that in the current climate of extensive deforestation and forest use, it is essential that all aspects of RIL systems are reevaluated in order to achieve economic and ecological sustainability.     

Filling the "vertical gap" between canopy tree species and understory shrub species:biomass allometric equations for subcanopy tree species

Subcanopy tree species are an important component of temperate secondary forests.However,their biomass equations are rarely reported,which forms a "vertical gap" between canopy tree species and understory shrub species.In this study,we destructively sampled six common subcanopy species(Syringa reticulate var.amurensis(Rupr.) Pringle,Padus racemosa(Lam.) Gilib.,Acer ginnala Maxim.,Malus baccata(Linn.) Borkh.,Rhamnus davurica Pall.,and Maackia amurensis Rupr.et Maxim.) to establish biomass equatio...     

The use of species–stem curves in sampling the development of the Zambian miombo woodland species in charcoal production and slash-and-burn regrowth stands

The use of fixed-area plot methods was considered unsuitable to compare the responses and recovery over time of different miombo woodland species to different land-use practices (i.e. charcoal production and slash-and-burn agriculture). Young regrowth stages have many stems and the older more advanced stages have fewer stems. Different land-use practices in miombo woodland impact on the recovery potential of the woodlands. Timber harvesting does not result in significant change in stocking of the woodland compared to changes in regrowth after vegetation clearing for either charcoal production or slash-and-burn agriculture. After such clearing the woodland regrowth changes from an initial high stocking to a much lower stocking over time. This study in Zambian Copperbelt miombo woodland assessed the feasibility to use species–stem curves to determine the optimum number of stems or plants to record at a sampling point in order to compare species recovery over time in regrowth stands 2–15 years after ending the slash-and-burn and charcoal production activities. The results show that 34 and 31 stems or plants for slash-and-burn and charcoal production regrowth stands, respectively, would adequately capture the representative number of species to describe the plant community of these regrowth stands. The research has also revealed that the use of fixed-area methods would result in the measuring of too many plants in one category (younger stands) with too few in the other category (advanced stands). Therefore, the study explains why, and concludes that, variable plot size is an appropriate method for sampling species recovery in regrowth stands.     

A simultaneous estimation procedure for the parameters of the maximum size–density line and self-thinning curve to predict stand development of fast-growing tropical species

A simultaneous estimation procedure for the parameters of two functions, i.e., the maximum size–density line and the self-thinning curve, is presented to predict stand development for fast-growing tropical species. This procedure assumes that the rate of periodic reduction in stand density with increasing quadratic mean diameter on a logarithmic scale (r) will increase inversely proportionally to the distance from the maximum size–density line and consequently equals the slope of the line at distance 0. Under this assumption, the maximum size–density line can be incorporated into the self-thinning curve to form an integrated equation with three parameters: k and m, the slope and constant of the maximum size–density line, and a, the rate of reduction of r of the self-thinning curve. These parameters are estimated simultaneously using measurement data on stand density, quadratic mean diameter, and the corresponding r. This procedure was evaluated by application to two data sets: 186 measurements of Acacia mangium and 95 measurements of Paraserianthes falcataria, for which the parameters k and m have previously been calculated. The parameters estimated using this procedure were in good agreement with previous ones based on the A. mangium data set, and the differences found for the P. falcataria data set were also small, within the error variances. Therefore, it is concluded that the proposed procedure would give almost the same estimates from a single calculation step as the previous procedure that required two separate calculation steps.     

Different xylogenesis responses to atmospheric water demand contribute to species coexistence in a mixed pine–oak forest

Seasonal patterns of wood formation(xylogenesis) remain understudied in mixed pine-oak forests despite their contribution to tree coexistence through temporal niche complementarity.Xylogenesis was assessed in three pine species(Pinus cembroides,Pinus leiophylla,Pinus engelmannii) and one oak(Quercus grisea) coexisting in a semi-arid Mexican forest.The main xylogenesis phases(production of cambium cells,radial enlargement,cell-wall thickening and maturation) were related to climate data consideri...     

Does it pay to do silvicultural research on a slow growing species?

This paper reports the results of a case study in the characterization of economics benefits of forestry research. An ex ante perspective is adopted given most of the impacts will occur well into the future. Improved methods of anticipating the benefits of research and technological change in forestry are needed given the increasing scarcity of research resources in the sector. The approach employed in this paper attempts to reflect the role of time lags in research, development and adoption, as well as the adoption costs, uncertainty and policy change. Both deterministic and stochastic cost-benefit algorithms were employed to calculate the benefits of silvicultural research on black spruce (Picea mariana [Mill.] B.S.P.), a relatively slow growing boreal tree species. Despite preconceptions that such research is not economically viable, the results suggest that silvicultural research on slow growing species may be a worthwhile investment. To be worthwhile from a wood growing perspective real stumpage values must increase through time. A priori justification of this particular silviculture and hence the research project also included improved wildlife habitat conditions. However, these benefits are ill-defined and probably should not be used as a rationale for either the research or the silvicultural practice itself without further study.     

Is there a Nordic Model for the treatment of introduced tree species? A comparison of the use,policy, and debate concerning introduced tree species in the Nordic countries

This article compares the use, policy, and debate concerning introduced tree species in the five Nordic countries (Finland, Sweden, Norway, Denmark, and Iceland). These countries have a long common history and are culturally similar. They are often framed under the benchmark of the “Nordic Model” or even the “Nordic Forestry Model”. Therefore, we hypothesize that the Nordic countries’ treatment of introduced tree species share common aspects, and that global environmental agreements and international currents in science and policy have reinforced these similarities. The comparison shows that globalization is strong and it seems, at least at a first glimpse, that the Nordic countries follow a kind of “Nordic Model” in their approach to introduced tree species. However, the history and importance of forestry, ecological conditions, afforestation campaigns, traditions of using introduced trees, understandings, and stakeholder positions have shaped different national and even regional path dependencies and circumstances. This, in turn, has transmuted international policy-making, regulations, and discussions into different specific ways to interpret, control, and implement the use of introduced trees in practice. This article concludes that global environmental agreements and international currents in science and policy adapt to diverse national contexts.     

Response of seedlings of different tree species to elevated C02 in Changbai Mountain

Eco-physiological responses of seedlings of eight species,Pinus koraiensis, Picea koraiensis, Larix olgensis, Populus ussuriensis, Betula platyphylla, Tilia amurensis, Traxinus mandshurica andAcer mono from broadleaved/Korean pine forest, to elevated CO₂ were studied by using open-top chambers under natural sunlight in Changbai Mountain, China in two growing seasons (1998–1999). Two concentrations of CO₂ were designed: elevated CO₂ (700 μmol·mol⁻¹) and ambient CO₂ (400 μmol·mol⁻¹). The study results showed that the height growth of the tree seedlings grown at elevated CO₂ increased by about 10%–40% compared to those grown at ambient CO₂. And the water using efficiency of seedlings also followed the same tendency. However, the responses of seedlings in transpiration and chlorophyll content to elevated CO₂ varied with tree species. The broad-leaf tree species were more sensitive to the elevated CO₂ than conifer tree species. All seedlings showed a photosynthetic acclimation to long-term elevated CO₂. Foundation item: The project was supported by National Key Basic Development of China (G1999043400) and the grant KZCX 406-4, KZCX1 SW-01 of the Chinese Academy of Sciences Biography: WANG Miao (1964-), maie, associate professor in Institute of applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

Species distribution models applied to plant species selection in forest restoration: are model predictions comparable to expert opinion?

An expert on local flora usually is the best option for plant species selection in most ecological restoration projects; although species selection often needs to be dealt with swiftly as well as on a limited budget, and obtaining the opinion of a local expert may not always be an economically viable alternative. In such cases, species distribution models (SDM) may offer a faster and more cost effective alternative. We asked six experts to rank native tree species according to their suitability at 24 forest sites. The predictive performance of the suitability rankings was evaluated by assessing their ability to discriminate present from absent species in the observed tree assemblages at each evaluation site. We used the area under the receiver operating characteristic curve to calculate the probability that the estimated suitability for a species present at a particular evaluation site is greater than the estimate for an absent species (both picked at random). Suitability rankings were also obtained from the predictions of SDM and the same procedure was used to estimate the predictive performance of the set of models at each site. The experts offered concordant suitability rankings at almost every evaluation site. There were no significant differences in the predictive performance of the SDM and four of the experts, although the SDM performed slightly better than the other two experts. Our results point to the suitability of the proposed species distribution modeling approach to obtain fast and cost effective recommendations for species selection in forest restoration projects.     

Thermal and photoperiodic requirements of the seedling stage of three tropical forest species

Air temperature and photoperiod play an important role in the seedling development for tropical forest species.Both variables are sensitive to climate,and so evaluating thermal and photoperiodic effects on seedling development is fundamental,especially for climate change studies.Methods to quantify thermal time and the energy required for plants to reach a development stage include air temperature and cardinal temperatures.The photoperiod will also affect physiological reactions of a plant and t...     

Responses of germination and radicle growth of two Populus species to water potential and salinity

The effects of water potential, NaCl and Na2SO4 on germination and radicle growth of two riparian tree species, Populus euphratica Oliv. and P. pruinosa Schrenk (Salicaceae), were tested. Growth chamber studies revealed an optimum temperature range for seed germination of both species between 15-35℃. The final germination percentage of both species decreases with decreasing water potential in all types of solution applied in the experiments. P. pruinosa was less tolerant to low ψw stress than P. euphratica, especially in salt solutions. Germination percentages fell below 20% for P. pruinosa at -0.6 MPa (NaCl) or -0.4 MPa (Na2SO4) and for P. euphratica at -1.2 MPa (NaCl) or-0.6 MPa (Na2SO4). Radicle growth of both species was inhibited by high concentrations of PEQ NaCl and Na2SO4. However, growth was enhanced at -0.13 and -0.29 MPa in PEG or at -0.13 MPa in NaCl solutions compared to distilled water. Radicle growth of P. euphratica was higher than that of P. pruinosa. Germination and radicle growth of both species exhibited ion toxicity. Na2SO4 was more toxic than iso-osmotic solutions of NaCl. Radicle growth proved to be more sensitive than seed germination. Thus, flooding does not only yield the necessary soil moisture for germination but also favors seedling establishment of both species through leaching of salts from the soil surface. The different sensitivity of the species during their early growth stages might, moreover, contribute to the observed differences in their distribution in the Talim Basin (northwest China).     

Swedish private forest owners’ perceptions and intentions with respect to adopting exotic tree species

Swedish forest growth can be increased through intensive forestry practices, enabling an increased use of forest biomass for climate-change mitigation. However, the diffusion of such practices depends on the forest owners’ adoption of them. We study Swedish private forest owners’ perceptions and intentions with respect to increasing forest growth by adopting exotic tree species. The results of a mail-in questionnaire survey show that although a majority of forest owners desire increasing forest growth, most owners have only a basic understanding of exotic tree species and a smaller proportion is interested in adopting them. The intention to adopt exotics seems to depend on the perceived performance of the species with respect to the economic aspects of forest management rather than on environmental or recreational concerns. Whereas a knowledge gap among the private forest owners regarding how to increase forest growth is implied, forest owners with higher self-rated knowledge of forestry and exotics have stronger intentions to adopt such species.     

Changes of plant species composition in the Šumava spruce forests,SW Bohemia,since the 1970s

Vegetation dynamics of three forest communities were studied by resampling of relevés recorded in the 1970s in the Bohemian Forest (Šumava Mountains). Results of multivariate analysis (RDA) confirmed significant time changes in species composition of the climax (Calamagrostio-Piceetum) and waterlogged (Bazzanio-Piceetum) spruce forests. The changes in the sphagnum-rich waterlogged spruce forests (Sphagno-Piceetum) are close to the level of significance. The main vegetation changes are represented by a decrease in cover and/or frequency of hygrophilous or sciophilous species (e.g. Athyrium distentifolium, Oxalis acetosella) in climax spruce forests, and an abundant increase of species, indicating a preference to drier stands or better light conditions (e.g. Calamagrostis villosa, Vaccinium vitis-idaea or Avenella flexuosa), in waterlogged spruce forests. We also found a higher proportion of meadow species (e.g. Anthoxanthum odoratum, Festuca rubra or Luzula multiflora) in the newly recorded relevés from waterlogged forests. Analysis of species number per plot showed a remarkable shift to species-rich communities, especially in waterlogged stands.We tried to find the possible factors responsible for the observed changes. Unfortunately, only indirect measurement of environmental factors using Ellenberg’s indicator values could be used and did not yield sufficient results. Thus, the changes observed in climax spruce forests were ascribed mainly to a decrease in canopy cover, which was directly estimated. In waterlogged forests, a complex of several general factors, which influence the climax spruce forest, had to be taken into account, such as: (i) a decrease in atmospheric acidification during the last 10–15 years and subsequent improvement in soil conditions, especially in waterlogged stands; (ii) fragmentation of forests as a result of bark-beetles attack; (iii) climate warming documented by long-term local meteorological measurements.     

Red-leafed species for urban “greening” in the age of global climate change

Urban trees provide vital ecosystem services such as mitigating heat island,improving air quality by removing various air pollutants,capturing rainwater,and acting as topsoil carbon storage.The aesthetic value of urban trees is also another feature that has to be considered in the context of urban greening.Classical criteria for the selection of urban trees have to respond to new challenges imposed to the cities in a near future.Global climate change factors increase the harshness of our cities,and thereby the plant resilience to abiotic stresses has also to be seriously considered for planning the urban greening.Red-leafed species,characterized by the permanent presence of foliar anthocyanins,show a greater tolerance to different environmental cues than green-leafed species commonly used in our cities.In addition,red tree species own a great aesthetic value which has been underestimated in the context of urban areas,especially in the harsh Mediterranean cities.In this study,we emphasize the "privilege of being red" from different point of view,in order to drive the attention to the possibility to increase the use of red-leafed species for urban "greening".Some possible negative aspects related to their use are rebutted and the direction of future researches are proposed.     

Can Hymenoscyphus fraxineus infect hardy members of the Oleaceae other than ash species?

The interaction between the ash dieback fungus, Hymenoscyphus fraxineus, and two commonly grown members of the Oleaceae (Forsythia × intermedia ‘Lynwood’ and Ligustrum vulgare) was investigated. Shoots were inoculated with three isolates of H. fraxineus and harvested after 2 and 10 weeks. DNA was extracted from tissue collected at the point of inoculation, as well as 15 mm below and above (distal), and analysed using fungal‐specific ITS primers and specific primers for H. fraxineus. The fungus was frequently detected in tissue at the point of inoculation, but rarely in distal samples. There was no evidence that H. fraxineus was pathogenic on either of the two oleaceous species over the duration of the experiment.     

Newly recorded species of the genus Isohypsibius （Tardigrada; Hypsibiidae） from China

This paper reports two newly recorded species, lsohypsibius lunulatus Iharos, 1966 and lsohypsibiusprosostomus Thulin, 1928, of the genus lsohypsibius （Tardigrada; Hypsibiidae） from China. The specimens of lsohysibius lunulatus were collected from Taibai Mt （34°18′N, 107°42′E） at 2,500 m a.s.1, and those oflsohypsibius prosostomus from Taibai Mt （34°10′N, 107°35′E） at 2,000 m above sea level. All specimens are deposited at the College of Life Sciences, Shaanxi Normal University, China. A key to the Chinese species of lsohypsibius was also given.     

Evaluating the deployment of alternative species in planted conifer forests as a means of adaptation to climate change—case studies in New Zealand and Scotland

Context

A strategy widely proposed for increasing the resilience of forests against the impacts of projected climate change is to increase the number of species planted to spread and reduce the risks from a range of biotic and abiotic hazards.

Aims

We tested this strategy in two case study areas in planted conifer forests in New Zealand and Scotland.

Methods

The performance of the major tree species and an alternative was compared: radiata pine and Eucalyptus fastigata in New Zealand and Sitka spruce and Scots pine in Scotland. The process-based model 3-PG2S was used to simulate the effects of projected climate change at the end of this century, with and without CO₂ fertilisation, upon productivity and financial returns. The effects of an abiotic hazard and two biotic hazards were considered.

Results

Under the current climate, the major species outperform alternatives in nearly all circumstances. However, with climate change, their relative performance alters. In New Zealand, planting of E. fastigata becomes more attractive particularly when various hazards and elevated CO₂ concentrations are considered. In Scotland, Scots pine becomes more attractive than Sitka spruce at lower interest rates.

Conclusions

The major plantation species in both countries are well suited to the current climate, but deployment of alternative species and/or breeds can help to adapt these planted forests to the impacts of climate change.     

Not erroneous but cautious conclusions about the potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest. Response to Björklund et al. (2015)

We argue that the conclusions drawn from the paper “The potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest”, published in the Scandinavian Journal of Forest Research were not erroneous as stated by a letter published in the same journal by Björklund et al. (2015. Erroneous conclusions about current geographical distribution and future expansion of forest insects in Northern Sweden: Comments on Hof and Svahlin (2015). Scand. J. Forest Res)”, but cautious. We regret possible underestimations caused by lack of occurrence records for some species for some areas. However, basing predictions of the impact of future climate change on the distribution of species on current range maps likely leads to grave overestimations of future range predictions since current range maps assume species are homogenously distributed throughout the landscape, which is often not the case. We argue that underestimating the distribution range of pest species rather than overestimating their distribution pinpoints areas that may need extra attention in future better, and therefore chose to be cautious rather than bold. We further like to stress that one should always be aware of possible insect outbreaks throughout the region, not only because predictions may underestimate the future distribution of species but also since the location and likelihood of insect pest outbreaks is not only determined by climatic factors.