Broadleaf Tree Species Research Articles

Estimating leaf inclination and G-function from leveled digital camera photography in broadleaf canopies

The effectiveness of using leveled digital camera for measuring leaf inclination angles was investigated in this study as an inexpensive and convenient alternative to existing approaches. The new method is validated with manual leaf angle measurements for various broadleaf tree species common to hemi-boreal region of Estonia and the tropical forests of Hawai’i Islands. The acquired leaf angle distributions suggest that planophile case might be more appropriate than the commonly assumed spherical as the general approximation of leaf orientation while modeling the radiation transmission through the canopies of (hemi)-boreal broadleaf stands. However, direct leaf inclination measurements should be obtained whenever possible, as there will always exist a large variety of leaf orientation, both among different species and in the space–time domain within a single species. The camera method tested in this study provides a new robust and affordable tool to obtain this information.

Effects of ozone exposure on growth and photosynthesis of the seedlings of Liriodendron chinense (Hemsl.) Sarg, a native tree species of subtropical China

Little is known about the response of trees to elevated ozone (O3) in the subtropical region of China, where ambient O3 concentrations are high enough to damage plants. In this study, pigment content, gas exchange and chlorophyll (Chl) a fluorescence in leaves of Liriodendron chinense (Hemsl.) Sarg seedlings, a deciduous broadleaf tree species native in subtropical regions, were investigated at 15, 40, and 58 days after O3 fumigation (DAF) at a concentration of 150 mm3 m-3 (E-O3). At the end of experiment, seedlings were harvested for biomass measurement. E-O3 caused visible injuries on the mature leaves e.g. necrotic patches and accelerated early defoliation. Relative to the charcoal-filtered air (CF) treatment, E-O3 significantly decreased shoot and root biomass, pigment content, light-saturated net photosynthesis (P Nsat), stomatal conductance (g s), maximum rate of carboxylation (Vcmax), photochemical quenching coefficient (qp) and effective quantum yield of PSII photochemistry (ΦPSII), and also caused a slight reduction in relative increase of basal diameter. Therefore, L. chinense can be assumed to be an O3-sensitive tree species, which will be threatened by increasing ambient O3 concentrations in China.

Variation in foliar δ 15N among oriental oak ( Quercus variabilis) stands over eastern China: Patterns and interactions

The patterns of variation in natural abundance of foliar and soil ( 15N) (expressed as δ 15N) related to geographical and climatic variables frequently vary over plant species or plant function groups. It is essential to identify the pattern of foliar δ 15N for specific plant species which has a widespread distribution and to explore the underlying mechanisms in the context of environmental change such as global warming and anthropogenic nitrogen deposition. Oriental oak ( Quercus variabilis Bl.), characterized by cork bark, is a widely distributing deciduous broadleaf tree species that can be found in temperate and subtropical areas of East Asia. In this study, the variations in foliar and soil 15N were investigated based on the data of leaf and soil samples collected in 22 stands over eastern China (from 24 to 41° N in latitude and 102 to 123° E in longitude), and the mechanisms were discussed. The results showed that for oriental oak stands, mean foliar and soil δ 15N were − 4.8‰ and 2.0‰, respectively, indicating an evident 15N enrichment in the soils. The average foliar δ 15N value of oriental oak in warm temperate forest was significantly lower ( p < 0.01), while a higher enrichment factor was also observed in temperate forests, than that in the subtropical areas. Over the eastern China, the foliar δ 15N increased linearly and significantly with increasing mean annual precipitation (MAP) (R 2 = 0.481 and p < 0.001) and mean annual temperature (MAT) (R 2 = 0.285 and p = 0.01) and decreasing pH value of rain water (R 2 = 0.333 and p = 0.005). With these results in eastern China, there are great implications in understanding how nitrogen dynamics of ecosystems responds to warming, drought and acid rain.

Effects of ozone exposure on sub-tropical evergreen Cinnamomum camphora seedlings grown in different nitrogen loads

The present study aims in investigating the individual and combined effects of ozone (O3) exposure and nitrogen (N) load on the growth and photosynthetic characters of Cinnamomum camphora seedlings, a dominant evergreen broadleaf tree species in sub-tropical regions. The seedlings were supplied with N as NH4NO3 solution at 0, 30 and 60 kg ha−1 year−1 (simplified as N0, N30, N60, respectively) and were exposed to ambient O3 concentration (AA) or elevated [O3] (E-O3, AA +60 ppb) for one growth season. E-O3 induced significant negative effects on foliar photosynthesis, including lower photosynthetic rate, reduced carboxylation efficiency, quantum yield of PSII and photosynthetic pigment contents, despite no effect on growth. In contrast, N load acted as fertilization effects. Medium N (N30) increased photosynthetic pigments and stem-base diameter growth relative to N0, whereas high N load (N60) significantly enhanced the growth, photosynthetic pigments, and dark and light action of photosynthesis of C. camphora seedlings. No significant interactive effects of O3 and N load on the growth, net photosynthetic rate and pigment contents of the seedlings were found, suggesting that N supply to the soil at ≤60 kg ha−1 year−1 does not significantly change the sensitivity of C. camphora to ozone.

Genomic sequencing and analyses of Lymantria xylina multiple nucleopolyhedrovirus

BackgroundOutbreaks of the casuarina moth, Lymantria xylina Swinehoe (Lepidoptera: Lymantriidae), which is a very important forest pest in Taiwan, have occurred every five to 10 years. This moth has expanded its range of host plants to include more than 65 species of broadleaf trees. LyxyMNPV (L. xylina multiple nucleopolyhedrovirus) is highly virulent to the casuarina moth and has been investigated as a possible biopesticide for controlling this moth. LdMNPV-like virus has also been isolated from Lymantria xylina larvae but LyxyMNPV was more virulent than LdMNPV-like virus both in NTU-LY and IPLB-LD-652Y cell lines. To better understand LyxyMNPV, the nucleotide sequence of the LyxyMNPV DNA genome was determined and analysed.ResultsThe genome of LyxyMNPV consists of 156,344 bases, has a G+C content of 53.4% and contains 157 putative open reading frames (ORFs). The gene content and gene order of LyxyMNPV were similar to those of LdMNPV, with 151 ORFs identified as homologous to those reported in the LdMNPV genome. Two genes (Lyxy49 and Lyxy123) were homologous to other baculoviruses, and four unique LyxyMNPV ORFs (Lyxy11, Lyxy19, Lyxy130 and Lyxy131) were identified in the LyxyMNPV genome, including a gag-like gene that was not reported in baculoviruses. LdMNPV contains 23 ORFs that are absent in LyxyMNPV. Readily identifiable homologues of the gene host range factor-1 (hrf-1), which appears to be involved in the susceptibility of L. dispar to NPV infection, were not present in LyxyMNPV. Additionally, two putative odv-e27 homologues were identified in LyxyMNPV. The LyxyMNPV genome encoded 14 bro genes compared with 16 in LdMNPV, which occupied more than 8% of the LyxyMNPV genome. Thirteen homologous regions (hrs) were identified containing 48 repeated sequences composed of 30-bp imperfect palindromes. However, they differed in the relative positions, number of repeats and orientation in the genome compared to LdMNPV.ConclusionThe gene parity plot analysis, percent identity of the gene homologues and a phylogenetic analysis suggested that LyxyMNPV is a Group II NPV that is most closely related to LdMNPV but with a highly distinct genomic organisation.

Herb layer response to broadleaf tree species with different leaf litter quality and canopy structure in temperate forests

AbstractQuestion: How do broadleaf tree species affect humus characteristics, herb layer composition and species diversity through their leaf litter quality and canopy structure?Location: Mixed broadleaf forests in Brandenburg, NE Germany.Methods: We studied the herb and tree layer composition in 129 undisturbed stands using a 10‐degree cover‐abundance and percentage scale, respectively. The main floristic gradients were extracted by non‐metric multidimensional scaling. Effects of tree species on the herb layer were analysed with partial Spearman rank correlation. We assessed affinities for specific tree species using indicator species analysis.Results: Both beech and oak influenced herb layer composition mainly through their litter quality, which resulted in deep Ol and Of horizons, respectively. The less dense canopy of oak, in contrast to the dense beech canopy, enhanced species diversity in favour of indifferent herb species (species not closely tied to forests). Lime was correlated with a distinct floristic gradient, but a direct effect on the herb layer cannot be proven with the available data. Effects of hornbeam were less pronounced.Conclusions: The relationship between the tree and herb layer must be partly attributed to pH differences. However, tree species effects on humus characteristics and on light flux to the ground were largely responsible as well. The results suggest that tree species can influence herb layer composition and diversity, but the missing correlation with lime and hornbeam raise questions requiring further detailed investigation.

Ecological and phytocenotic features of the bryophyte component of water protection forests on the Ufa Plateau

The composition of bryophytes in forests of the Ufa Plateau has been studied. The results obtained by ordination methods show that the coverage of epigeic mosses decreases with an increase in tree stand density and proportion of broadleaf tree species as well as in the coverage and average height of herbaceous layer. The main factors determining the distribution of epigeic mosses are illumination level, soil fertility, and the degree of soil development.

Stomatal Length Correlates with Elevation of Growth in Four Temperate Species†

Stomatal size and density are considered two key ecophysiological parameters, because they jointly influence stomatal conductance. In the present study, we examine trends in these anatomical traits along a 660-m elevational gradient on Mt. Moosilauke, in the White Mountains of New Hampshire. Samples were collected from two broadleaf tree species (Betula papayrifera var. cordifolia and Sorbus americana) and two herbaceous understory species (Cornus canadensis and Dryopteris carthusiana). Guard cell length increased with elevation in all four species (all p ≤ .10), but there were no clear elevational trends in stomatal density in any of the four species (all p ≥ .10). A “potential conductance index” [= (guard cell length)2 × stomatal density × 10−4] was positively correlated with elevation for all species, but this trend was significant only for the two understory species (both p ≤ .10). Results are discussed in the context of prevailing theories to explain changes in stomatal traits with elevation.

Seasonal changes in nitrate use by three woody species: the importance of the leaf-expansion period

Seasonal changes in plant NO3−-N use were investigated by measuring leaf nitrate reductase activity (NRA), leaf N concentration, and leaf expansion in one evergreen woody species (Quercus glauca Thunb.) and two deciduous woody species [Acer palmatum Thunb. and Zelkova serrata (Thunb.) Makino]. Leaf N concentration was highest at the beginning of leaf expansion and decreased during the expansion process to a steady state at the point of full leaf expansion in all species. The leaf NRA of all species was very low at the beginning of leaf expansion, followed by a rapid increase and subsequent decrease. The highest leaf NRA was observed in the middle of the leaf-expansion period, and the lowest leaf NRA occurred in summer for all species. Significant positive correlations were detected between leaf NRA and leaf expansion rates, while leaf N concentrations were negatively correlated with leaf area. In the evergreen Q. glauca, the N concentration in current buds increased before leaves opened; concurrently, the N concentration in 1-year-old leaves decreased by 25%. Our results show that the leaf-expansion period is the most important period for NO3−-N assimilation by broadleaf tree species, and that decreases in leaf N concentration through the leaf-expansion period are at least partly compensated for by newly assimilated NO3−-N in current leaves.

Variation in seed production among years and among individuals in 11 broadleaf tree species in northern Japan

Seed production is the most problematic part of tree regeneration and is the least amenable to control by silvicultural management. Understanding variability in seed production among years and among trees will allow better planning of seed collection for seedling production and natural regeneration. We estimated the extent of variability in seed production among years and within years among individual trees. Specifically, we measured individual annual seed production in 11 woody species in Hokkaido, northern Japan. We analyzed the coefficient of variation (CV) of seed production among years and among individual trees. We used population- and individual-based CVs (CVpt and ) to estimate the variability in seed production among individual trees. Alnus hirsuta, in which these CVs among trees were maximal, will require further analyses of the spatial patterns of seed production among individual trees. Additionally, we used population- and individual-based CVs (CVpy and ) to estimate the variability in seed production among years. The was statistically higher than in 2 of the 11 species: Betula maximowicziana and Sorbus alnifolia. Activities for the regeneration of these species should regard the annual variation in seed production as more important than individual variation. For the nine species in which was similar to even if seed production by specific trees was not sufficient for regeneration in a particular year, other trees or stands often had high seed production in that year. We discuss the relative importance of annual and individual variability in determining efficient methods for artificial and natural regeneration of these woody plant species.

Vegetation development in second rotation Irish conifer plantations

The development of regenerating trees and ground flora in second rotation conifer plantations on the dredged sediments of a lowland river is assessed. A high density of ash ( Fraxinus excelsior) and sycamore ( Acer pseudoplatanus) was recorded in sample plots. Most individuals had regenerated prior to first rotation harvesting. There were large numbers of birch ( Betula pubescens), most of which had regenerated after harvesting. Five non-native (introduced), broadleaf tree species and three non-native conifer tree species had also regenerated. The abundance of ground flora species typical of Irish broadleaf woodlands declined with time from first rotation felling. The causes were the clear-fell process and tree crop canopy development with time. Second rotation plantation restructuring was also involved. During this process, dense-canopy spruce ( Picea spp.) was planted on sites formerly occupied by the open-canopy conifer species, larch ( Larix spp.) or pine ( Pinus spp.) and broadleaf woodland trees were planted on sites formerly occupied by spruce. We conclude that silvicultural alternatives to clear-fell, such as continuous tree cover are feasible but that they will facilitate the establishment of woodland tree communities new to biogeographically isolated Ireland. Maintaining the continuity of open-canopy tree crops on sites with an established broadleaf woodland ground flora species is key for retaining the biodiversity gains of first rotation. We highlight the importance of strategic forest planning decisions in achieving this.

Contrasting below- and aboveground responses of two deciduous trees to patchy nitrate availability

We investigated how patchy nitrate availability influences growth and functioning of plant roots and generates, through vascular constraints on long-distance transport, aboveground heterogeneity in plant growth and chemistry. We examined two broadleaf tree species, Acer rubrum L. and Betula papyrifera Marsh. Plants were grown either in a split-root setup where a single root received full nutrient supply and the rest of the root system received all nutrients except nitrogen (patchy treatment), or in a single pot with full nutrient supply (homogeneous treatment). In both species, fine roots proliferated in the nitrogen patch, but B. papyrifera produced twice as much fine root biomass in response to patchy nitrate availability as did A. rubrum. There was no difference between treatments in nitrogen uptake rate in either species. In general, specific water uptake was higher in A. rubrum than in B. papyrifera, especially in the nitrogen-rich side pot. When nitrate availability was patchy, nitrate reductase activity in roots and leaves was unaffected in either species. In A. rubrum, but not in B. papyrifera, patchy nitrate supply resulted in aboveground heterogeneity, with leaves above the N-fertilized roots being larger and having a higher relative chlorophyll concentration than those inserted in the opposite quater of the stem.

Selection of a set of specific primers for the identification ofTuber rufum: a truffle species with high genetic variability

Tuber rufum is a truffle widely distributed throughout Europe, which forms mycorrhizal associations with numerous species of broadleaf and coniferous trees. The possibility of T. rufum contamination in commercial truffle-infected plants makes its detection important. To facilitate the identification of T. rufum from mycorrhiza and fruitbodies, species-specific primers were designed and tested. To overcome the high intraspecific genetic variability within the internal transcribed spacer (ITS) regions of T. rufum, as demonstrated by phylogenetic analysis, two forward primers, Ru1f and Ru2f, located on the ITS1 region were designed to be used in concert with the reverse primer ITS4. Only T. rufum was amplified with this primer combination, while DNA of Tuber magnatum, Tuber brumale, Tuber maculatum, Tuber borchii, Tuber excavatum and Tuber melanosporum was not. These primers give a specific amplicon ranging between 566 and 572 bp and are able to discriminate between T. rufum, T. borchii and T. magnatum in multiplex PCR. In addition, T. rufum-specific amplicons were obtained from both spore suspensions and mycorrhiza by direct PCR. Tuber rufum mycorrhiza obtained in the greenhouse using mycelial inoculation techniques had morphological features similar to those of other species of Tuber, stressing the importance of molecular tools for their identification.

Early results from genetic trials on the growth of Spanish cedar and its susceptibility to the shoot borer moth in the Yucatan Peninsula, Mexico

Cedrela odorata (Spanish cedar) is a neotropical broadleaf tree species that is in high demand for furniture and interior fittings. In 1998, seed collections were made from Spanish cedar in the Yucatan Peninsula, Mexico, for genetic conservation and tree improvement projects. Progeny from these collections were established in genetic trials at Bacalar, Noh Bec, and Zoh Laguna in the Yucatan. Survival at 2 years was 73.5% at Bacalar, 72% at Noh Bec, but only 20% after 6 months for several replicates at Zoh Laguna. Mean 2-year height, number of years of Hypsipyla attack on apical shoots (over 2 or 3 years) and total branching over 2 years, were 1.3 m, 0.04 years, and 2.5 branches at Bacalar, and 1.9 m, 0.35 years, and 1.6 branches at Noh Bec. Selection of the three best provenances (Escárcega, Bacalar, and Calakmul) would result in an estimated cross-site gain of 8.6% in 2-year height. Within-provenance, cross-site heritabilities for 2-year height, shoot borer attack, and branching were 0.1 ± 0.02, 0.0 ± 0.02, and 0.0 ± 0.02, respectively. Single-site heritabilities for height at 2 years, shoot borer attack, and branching were 0.09 ± 0.05, 0.02 ± 0.04, and 0.09 ± 0.05 at Bacalar and 0.16 ± 0.07, 0.0 ± 0.06, and 0.0 ± 0.07 at Noh Bec. Given the known advantage of rapid growth to avoid Hypsipyla damage over the long term and the stable performance of provenances across sites for growth traits, we recommend provenance selection over multiple trials to reduce the risk of serious damage by the insect. Good provenances and other suitable seed sources, as well as proper site selection and silvicultural practices, are important tools for increasing yields from plantations of C. odorata.

Induction of photosynthesis and importance of limitations during the induction phase in sun and shade leaves of five ecologically contrasting tree species from the temperate zone

We examined the principal differences in photosynthetic characteristics between sun and shade foliage and determined the relative importance of biochemical and stomatal limitations during photosynthetic induction. Temperate-zone broadleaf and conifer tree species, ranging widely in shade tolerance, were investigated from one locality in the Czech Republic. The study species included strongly shade-tolerant Abies alba Mill. and Tilia cordata Mill., less shade-tolerant Fagus sylvatica L. and Acer pseudoplatanus L. and sun-demanding Picea abies (L.) Karst. In the fully activated photosynthetic state, sun foliage of all species had significantly higher maximum CO(2) assimilation rates, maximum stomatal conductance and maximum rates of carboxylation than shade foliage. Compared with shade leaves, sun leaves had significantly higher nocturnal stomatal conductances. In all species, shade foliage tended to have higher induction states 60 s after leaf illumination than sun foliage. Sun and shade foliage did not differ in the rate of disappearance of the transient biochemical limitation during the induction phase. Longer time periods were required to reach 90% photosynthetic induction and 90% stomatal induction in sun foliage than in shade foliage of the less shade-tolerant F. sylvatica and A. pseudoplatanus and in sun-demanding P. abies; however, in sun foliage of the strongly shade-tolerant species T. cordata and A. alba, the time needed for photosynthetic induction was similar to, or less than, that for shade foliage. Shade but not sun needles of P. abies and A. alba had significantly slower induction kinetics than the broadleaf tree species. Among species, the sun-demanding P. abies exhibited the shortest stomatal induction times in both sun and shade leaves. Independently of shade tolerance ranking, the transient stomatal and total limitations that characterize photosynthetic induction were relieved significantly earlier in shade foliage than in sun foliage. Sun foliage generally exhibited a hyperbolic photosynthetic induction response, whereas a sigmoidal induction response was more frequent in shade foliage. The different relative proportions of transient biochemical and stomatal limitations during photosynthetic induction in sun and shade foliage indicate an essential role of stomata in photosynthetic limitation during induction, mainly in shade foliage, with a consequent influence on the shape of the photosynthetic induction curve.

Remote sensing-based predictors improve distribution models of rare, early successional and broadleaf tree species in Utah.

Summary 1Compared to bioclimatic variables, remote sensing predictors are rarely used for predictive species modelling. When used, the predictors represent typically habitat classifications or filters rather than gradual spectral, surface or biophysical properties. Consequently, the full potential of remotely sensed predictors for modelling the spatial distribution of species remains unexplored. Here we analysed the partial contributions of remotely sensed and climatic predictor sets to explain and predict the distribution of 19 tree species in Utah. We also tested how these partial contributions were related to characteristics such as successional types or species traits.2We developed two spatial predictor sets of remotely sensed and topo‐climatic variables to explain the distribution of tree species. We used variation partitioning techniques applied to generalized linear models to explore the combined and partial predictive powers of the two predictor sets. Non‐parametric tests were used to explore the relationships between the partial model contributions of both predictor sets and species characteristics.3More than 60% of the variation explained by the models represented contributions by one of the two partial predictor sets alone, with topo‐climatic variables outperforming the remotely sensed predictors. However, the partial models derived from only remotely sensed predictors still provided high model accuracies, indicating a significant correlation between climate and remote sensing variables. The overall accuracy of the models was high, but small sample sizes had a strong effect on cross‐validated accuracies for rare species.4Models of early successional and broadleaf species benefited significantly more from adding remotely sensed predictors than did late seral and needleleaf species. The core‐satellite species types differed significantly with respect to overall model accuracies. Models of satellite and urban species, both with low prevalence, benefited more from use of remotely sensed predictors than did the more frequent core species.5 Synthesis and applications. If carefully prepared, remotely sensed variables are useful additional predictors for the spatial distribution of trees. Major improvements resulted for deciduous, early successional, satellite and rare species. The ability to improve model accuracy for species having markedly different life history strategies is a crucial step for assessing effects of global change.

C and N stocks under three plantation forest ecosystems of Chinese fir, Michelia macclurei and their mixture

Chinese fir (Cunninghamia lanceolata), a type of subtropical fast-growing conifer tree, is widely distributed in South China. Its plantation area covers more than 7 × 106 hm2, accounting for 24% of the total area of plantation forests in the country. In recent decades, the system of successive plantation of Chinese fir has been widely used in southern China due to anticipated high economic return. However, recent studies have documented that the practice of this system has led to dramatic decreases in soil fertility and forest environment as well as in productivity. Some forest ecologists and managers recognize the ecological role performed by broadleaf trees growing in mixtures with conifers, and a great deal of studies on mixture effects have been conducted, particularly on mixture species of temperate and boreal forests, but these research results were not completely consistent. Possibilities include dependence of the mixture effects in large part to specific site conditions, the interactions among species in mixtures and biological characteristics of species. Although some researchers also studied the effects of mixtures of Chinese fir and broadleaf tree species on soil fertility, forest environment and tree growth status, little information is available about the effects of Chinese fir and its mixtures with broadleaves on carbon and nitrogen stocks. The experimental site is situated at the Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, Hunan Province (26°40′–27°09′ N, 109°26′–110°08′ E). It is located at the transition zone from the Yunnan-Guizhou Plateau to the low mountains and hills of the southern bank of the Yangtze River at an altitude of 300–1,100 m above mean sea level. At the same time, the site is also a member of the Chinese Ecosystem Research Network (CERN), sponsored by the Chinese Academy of Sciences (CAS). This region has a humid mid-subtropical monsoon climate with a mean annual precipitation of 1,200–1,400 mm, most of the rain falling between April and August, and a mean temperature of 16.5°C with a mean minimum of 4.9°C in January and a mean maximum of 26.6°C in July. The experimental field has red-yellow soil. After a clear-cutting of the first generation Chinese fir (Cunninghamia lanceolata) plantation forest in 1982, three different plantation forest ecosystems, viz. mixture of Michelia macclurei and Chinese fir (MCM), pure Michelia macclurei stand (PMS) and pure Chinese fir stand (PCS), were established in the spring of 1983. A comparative study on C and N stocks under these three plantation forest ecosystems was conducted in 2004. Results showed that carbon stocks were greater under the mixtures than under the pure Chinese fir forest and the pure broad-leaved forest, and the broadleaves and the mixtures showed higher values in nitrogen stocks compared with the pure Chinese fir forest. The spatial distribution of carbon and nitrogen stocks was basically consistent, the value being greater in soil layer, followed by tree layer, roots, understory and litter layer. The carbon and nitrogen stocks in soil layer were both highly correlated with the biomass in understory and litter layer, indicating that understory and forest litterfall exerted a profound effect on soil carbon and nitrogen stocks under plantation ecosystems. However, correlations among soil carbon, nitrogen stocks and below ground biomass of stand have not been observed in this study.

Determinants of parasitoid abundance and diversity in woodland habitats

Summary Insect parasitoids comprise a large fraction of terrestrial biodiversity. Because of this diversity, species‐level conservation of most parasitoid species is impractical and habitat conservation must substitute. However, habitat indicators of parasitoid abundance and diversity are poorly known. To identify such habitat indicators, parasitoid wasps in four ichneumonid subfamilies were sampled in the field herb layer of 15 woodlands in the Vale of York, UK, using Malaise traps. The catch was related to vegetation characteristics. A total of 1543 individuals in 60 species was recorded, representing 36% of UK species in the taxa sampled. Parasitoids tended to be more abundant and species rich in woodlands with a high broadleaf content and tree species richness. This pattern was observed in the ichneumonid subfamilies Pimplinae, Poemeniinae and Diacritinae. However, the ichneumonid subfamily Diplazontinae was found to vary in abundance and richness within rather than between woodlands and showed no association with measured habitat variables. Reserve selection analyses indicated that coniferous woodlands, and woodlands with a low abundance and richness of parasitoids, none the less can contribute to maximizing parasitoid diversity at the landscape scale. Synthesis and applications. At the individual woodland scale, broadleaved woodlands with high tree species richness appear best for conserving parasitoid abundance and diversity. At a landscape scale however, a variety of woodland habitat types can maximize diversity of all parasitoid taxa. We hypothesize that the degree of association between parasitoid abundance and diversity, and characteristics of the vegetation within habitats will decrease with an increase in the number of trophic links that separate them.

Decrease in the capacity for RuBP carboxylation and regeneration with the progression of cold-induced photoinhibition during winter in evergreen broadleaf tree species in a temperate forest.

We measured the photosynthetic capacity (RuBP carboxylation and electron transport capacity at 25°C) and the maximum photochemical efficiency (Fv/Fm) from autumn to spring in saplings of two evergreen broadleaf tree species and examined the negative effects of photoinhibition on the photosynthetic capacity. Saplings were grown in pots under three simulated natural light environments typical of temperate forests: an open site, deciduous understorey and evergreen understorey. During winter, the photosynthetic capacity and Fv/Fm synchronously decreased in leaves in the sun, but not those in the shade. We found large differences in Fv/Fm and photosynthetic capacity, along with a positive correlation between Fv/Fm and the photosynthetic capacity among leaves in different light environments. In photoinhibited leaves that were transferred to the shade in mid-winter, photosynthetic capacity increased synchronously with the increment of Fv/Fm. The decrease in photosynthetic capacity in photoinhibited leaves and the synchronous recovery of photosynthetic capacity with photoinhibition supported the hypothesis that photoinhibition depressed the photosynthetic capacity during winter. We showed that difference in the degree of photoinhibition was responsible for the different winter photosynthetic capacity among leaves exposed to different light environments.

Tension Wood Formed in Fagus Sylvatica and Alnus Glutinosa After Simulated Mass Movement Events

Due to the likelihood of global climate change, the frequency and magnitude of natural hazards such as mass movements may likewise change, thus favouring the refinement of methods to detect and quantify geomorphic events when precise records are not available. Geomorphic events typically have a significant effect on tree growth, e.g., reaction wood marked by changes in ring widths and wood density. To date, several dendroecological techniques have been developed to document the occurrence of these events but it rarely has been possible to retrieve additional information from reaction wood concerning the precise kind and intensity of geomorphic events. Additional qualitative information inferred from reaction wood of trees holds the potential to not only document but also estimate important characteristics of natural hazard events. To refine the methods already used in dendrogeomorpology, experiments simulating various geomorphic events were used to monitor subsequent wood anatomical responses of Fagus sylvatica and Alnus glutinosa. The preliminary results indicate that these two common broadleaf tree species show variations in their reactions to different experimental treatments.