Scaling-up from tree to stand transpiration for a warm-temperate multi-specific broadleaved forest with a wide variation in stem diameter

Previous studies have demonstrated a clear relationship between diameter at breast height (DBH) and tree transpiration (Q _T) in multi-specific broadleaved forests. However, these studies were conducted with a limited range of tree sizes and species, and thus many multi-specific broadleaved forests fall outside these conditions. Therefore, this study examined the relationship between DBH and Q _T in a warm-temperate multi-specific broadleaved forest (n = 12 species) with a wide range of tree sizes (5.0–70.0 cm DBH) using the Granier-type heat dissipation method. The results showed that, although sap flow density varied between individual trees and species, there was a significant relationship between log Q _T and log DBH (r ² = 0.66, P < 0.001) because of the strong dependence of sapwood area on DBH. This study confirmed the applicability of the relationship for the stand transpiration (E _C) estimates even in a multi-specific broadleaved forest with a wide variation in DBH. Our results also revealed that selecting the sample trees in descending order of DBH effectively reduced potential errors in E _C estimates for a specific sample size, as larger trees contribute more to E _C. This information should be useful for future studies investigating the transpiration of multi-specific broadleaved forests, reducing errors during the scaling-up procedure.     

Modeling height–diameter relationship for <Emphasis Type="Italic">Populus euphratica</Emphasis> in the Tarim riparian forest ecosystem,Northwest China

Modeling height–diameter relationships is an important component in estimating and predicting forest development under different forest management scenarios. In this paper, ten widely used candidate height–diameter models were fitted to tree height and diameter at breast height(DBH)data for Populus euphratica Oliv. within a 100 ha permanent plots at Arghan Village in the lower reaches of the Tarim River, Xinjiang Uyghur Autonomous Region of China. Data from 4781 trees were used and split randomly into two sets:75 % of the data were used to estimate model parameters(model calibration), and the remaining data(25 %) were reserved for model validation. All model performances were evaluated and compared by means of multiple model performance criteria such as asymptotic t-statistics of model parameters, standardized residuals against predicted height,root mean square error(RMSE), Akaike’s informationcriterion(AIC), mean prediction error(ME) and mean absolute error(MAE). The estimated parameter a for model(6) was not statistically significant at a level of a = 0.05. RMSE and AIC test result for all models showed that exponential models(1),(2),(3) and(4) performed significantly better than others. All ten models had very small MEs and MAEs. Nearly all models underestimated tree heights except for model(6). Comparing the MEs and MAEs of models, model(1) produced smaller MEs(0.0059) and MAEs(1.3754) than other models. To assess the predictive performance of models, we also calculated MEs by dividing the model validation data set into 10-cm DBH classes. This suggested that all models were likely to create higher mean prediction errors for tree DBH classes[20 cm. However, no clear trend was found among models.Model(6) generated significantly smaller mean prediction errors across all tree DBH classes. Considering all the aforementioned criteria, model(1): TH ? 1:3 t a= e1 t b?eàc?DBHT and model(6): TH ? 1:3 t DBH2= ea t b?DBH t c ? DBH2T are recommended as suitable models for describing the height–diameter relationship of P. euphratica. The limitations of other models showing poor performance in predicting tree height are discussed. We provide explanations for these shortcomings.     

Diversity and structural composition of species in dipterocarp forests: a study from Fasiakhali Wildlife Sanctuary,Bangladesh

Fasiakhali Wildlife Sanctuary is a protected area composed of tropical remnant rainforest that harbor substantial number of large,old Garjan(Dipterocarpus spp.)trees.The present study assessed composition,structure and diversity of the species in this protected area.A total of 32 trees species were recorded with DBH ≥ 11 cm belonging to 24 genera and 19 families.The forest is low in plant diversity as represented by Shannon–Wiener diversity and Simpson Dominance indices.Dipterocarpus turbinatus was the most dominant species with maximum relative density,frequency,dominance,and importance value index.Syzygium firmum and Tectona grandis followed in terms of dominance.The structural composition indicated higher number of individuals in the medium growth classes(41 to 511 cm DBH and 16–20 m height ranges),whereas D.turbinatus was the only species that dominated most of the growth classes.Poor stem density in lower growth classes indicated meager recruitment of regeneration which may be due to lower annual precipitation,increased grazing and encroachments.This study will help to understand the patterns of tree species composition and diversity in the remnant dipterocarp forests of Bangladesh.It will also contribute to identifying threatened plants to undertake D.turbinatus based conservation and sustainable management of the Fasiakhali Wildlife Sanctuary.     

Differences in transpiration between a forest and an agroforestry tree species in the Sudanian belt

Average population growth in the African Sudanian belt is 3 % per year. This leads to a significant increase in cultivated areas at the expense of fallows and forests. For centuries, rural populations have been practicing agroforestry dominated by Vitellaria paradoxa parklands. We wanted to know whether agroforestry can improve local rainfall recycling as well as forest. We compared transpiration and its seasonal variations between Vitellaria paradoxa, the dominant species in fallows, and Isoberlinia doka, the dominant species in dry forests in the Sudanian belt. The fallow and dry forest we studied are located in northwestern Benin, where average annual rainfall is 1200 mm. Sap flow density (SFD) was measured by transient thermal dissipation, from which tree transpiration was deduced. Transpiration of five trees per species was estimated by taking into account the radial profile of SFD. The effect of the species and of the season on transpiration was tested with a generalized linear mixed model. Over the three-year study period, daily transpiration of the agroforestry trees, V. paradoxa (diameters 8–38 cm) ranged between 4.4 and 26.8 L day^?1 while that of the forest trees, I. doka, (diameters 20–38 cm) ranged from 9.8 to 92.6 L day^?1. Daily transpiration of V. paradoxa was significantly lower (15 %) in the dry season than in the rainy season, whereas daily transpiration by I. doka was significantly higher (13 %) in the dry season than in the rainy season. Our results indicate that the woody cover of agroforestry systems is less efficient in recycling local rainfall than forest cover, not only due to lower tree density but also to species composition.     

Soil aggregate characteristics and stability of soil carbon stocks in a <Emphasis Type="Italic">Pinus tabulaeformis</Emphasis> plantation

Pinus tabulaeformis has been widely planted in order to conserve soil and water and improve the ecological environment in China. This study aimed to unravel how soil aggregates and soil carbon (C) stock stability of a P. tabulaeformis plantation change after 60 years of natural development and was performed in Vitex negundo var. heterophylla and Ziziphus jujuba var. spinosa shrub (shrub), a P. tabulaeformis forest (pine), and a coniferous broadleaf P. tabulaeformis mixed forest (pine-oak). Afforestation increased the stability of soil aggregates in the 0–10 cm soil layer but resulted in a decrease in the 10–20 cm soil layer. However, the presence of deciduous broadleaf species in the pine plantation improved the stability of soil aggregates. The total soil C stock was increased by afforestation, especially in the pine-oak forest, where it reached a significant level. The mineral soil C stock in the shrub stand was higher than that in pine and lower than that in pine-oak forests, but the C fractions had a different change. Afforestation increased the C fraction of macroaggregates in the 0–10 cm soil layer but decreased it in the 10–20 cm soil layer. This result suggested that afforestation could improve soil C stabilization in deeper soil. However, the pine-oak forest had a higher C fraction of macroaggregates than the pine forest in the 10–20 cm soil layer, indicating that soil C stabilization of the P. tabulaeformis plantation decreased when deciduous broadleaf species were present and thus formed the coniferous broadleaf mixed forest.     

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.     

An assessment of potential of hybrid poplar for planting in the Virginia Piedmont

Poplar species grow well across the temperate zone, but hybrid varieties have not previously been evaluated for planting in the Virginia Piedmont region. The top 12 clones in height growth and rust resistance from a screening trial involving 98 hybrid poplar varieties of three taxa (Populus deltoides × P. maximowiczii, DxM; P. deltoides × P. nigra, DxN; P. deltoides × P. trichocarpa, DxT) were selected for planting in replicated yield trials at two locations in the Virginia Piedmont. Results through the first four growing seasons showed that the DxM taxon had the most rapid height development. It was, however, the taxon most affected by a late spring frost at the Appomattox-Buckingham State Forest site and by Septoria stem canker at the Reynolds Homestead site. Analysis of variance of clonal and location effects showed highly significant differences among replicates within location and among clones within taxon. Among seven clones within the DxM taxon, pairwise comparison tests of height growth identified two groups: a group of four better clones that were significantly different (p = 0.05) from a second group of three. These early results suggest that multi-selection criteria, including growth, disease and frost resistance, are important when developing hybrid poplar clones for planting in the Piedmont region.     

Influence of distance to forest edges on natural regeneration of abandoned pastures: a case study in the tropical mountain rain forest of Southern Ecuador

In spite of its high diversity the forests in Southern Ecuador are highly endangered by deforestation. One of the main reasons for the loss of forests is the conversion into pastures. Due to their fast degradation, the pastures are abandoned after several years and form an increasing area of unproductive land. The remoteness from existing forest edges is discussed as one reason for the very slow natural reforestation of these areas. In this study we analyzed the regeneration of a secondary forest after approx. 38 years of succession in relation to the distance from the surrounding forest. We revealed that regeneration was rather slow. Especially larger trees with dbh > 10 cm were very scarce. Only Dioicodendron dioicum, Graffenrieda emarginata and Clusia sp. achieved larger diameters. The basal area of the secondary forest is still far beyond the original level in the primary forest. The number of species on plot level and the Shannon index were significantly lower in the secondary forest compared to the primary forest. The total number of species decreased from 47 to 31 with increasing distance from the forest edge and the similarity of species composition to the upper story declined to a level of 56.4 (Sörensen). Alzatea verticillata, Macrocarpea revoluta and Palicourea andaluciana had significantly higher abundances in the succession stages than in the natural forest. The most abundant species in all regeneration plots, G. emarginata and Purdiea nutans, seem to be generalists as they did not show preference either to natural forest or successional stages.     

Comparison of leaf stomatal conductance models for typical desert riparian phreatophytes in northwestern China

Stomatal regulation plays a vital role related to plant functioning, especially with a limited water supply. Estimating the leaf stomatal conductance (g _s) is pivotal for further estimation of transpiration as well as energy and mass balances between air and plant in arid regions. Based on successive measurements of leaf gas exchange of two typical desert riparian phreatophytes, Tamarix ramosissima Ledeb., and Populus euphratica Oliv., we estimated g _s using the empirical, optimal, and mechanistic models. Measurements were conducted on T. ramosissima during the growing seasons in 2011 and 2012 and P. euphratica in 2013 and 2014. Estimated values were compared with those measured by the portable open-path gas exchange measurement system. Results indicated that Ye’s mechanistic model always performed best among all the g _s models tested here with R ² values of 0.878 and 0.723 for T. ramosissima in 2011 and 2012, and 0.625 and 0.867 for P. euphratica in 2013 and 2014, respectively. Meanwhile, Medlyn’s optimal model exhibited the least reliable performance with R ² at values of 0.514 and 0.398 for T. ramosissima in 2011 and 2012, and 0.385 and 0.101 for P. euphratica in 2013 and 2014, respectively. Empirical models may not be suitable for application in novel situations because they have been developed from experimental observations rather than from any mechanistic understanding or theory of stomatal behavior. Consequently, the application of Ye’s mechanistic model will be of great significance for the modeling and up-scaling of g _s in extremely arid regions in the future.     

Seed bank and regeneration dynamics of <Emphasis Type="Italic">Emmenopterys henryi</Emphasis> population on the western side of Wuyi Mountain,South China

Emmenopterys henryi Oliv. (Rubiaceae) is an endangered tree species that is native to China. The wild populations of E. henryi have declined rapidly because of its poor natural regeneration, but the actual regeneration processes are not yet understood. In field tracking surveys and experiments in the Wuyishan Nature Reserve in Southeast China to determine the most important stage that affects the regeneration process, seed bank characteristics, seed germination, and seedling growth dynamics were studied in the typical habitats of E. henryi, Phyllostachys pubescens and broad-leaved forests. Results showed that in both P. pubescens and broad-leaved forests, more than 70% of the E. henryi seeds were distributed in moss and litter layers, and few were found in the soil beneath them. However, seed germination in the soil layer was significantly higher than in the moss and litter layers. Seed density, overall seed quality, and germination rate in the broad-leaved forest were significantly higher than in P. pubescens forest. Seed germination was highest in the microsites around the edge of the crown projection area of E. henryi mother trees. The order of survival rate of the seedlings on different ground surfaces was soil > moss > litter. In both habitats, the average seed density was 24.9 seeds m^?2, and the total germination rate was less than 3.5‰. However, seedlings developed from only 1% of the germinated seeds, indicating that the seed germination is the most important stage in the natural regeneration of E. henryi.     

The populations and distribution of <Emphasis Type="Italic">Pieris japonica</Emphasis>, a poisonous tree protected from herbivore browsing pressure,increase slowly but steadily

Pieris japonica is a poisonous tree species that is rarely eaten by herbivorous animals, a fact that could enable the expansion of its distribution range and influence ecosystems into which it encroaches. In a regional-scale study, 300 P. japonica trees from 13 populations were sampled at the University of Tokyo Chichibu Forest, Japan, and were analyzed using 11 microsatellite markers. Genetic differentiation among the populations was low (F _ST = 0.022 and G′ _ST = 0.024). A plot (30 × 30 m) was established for a fine-scale study, in which all P. japonica trees and saplings were measured and genetically analyzed using the microsatellite markers. Using this approach, we detected 84 genotypes among the 121 P. japonica trees in the plot. A few genotypes had expanded by more than 5 m, indicating that the ability to reproduce asexually could facilitate P. japonica trees to remain in a given location. Autocorrelation analysis showed that the extent of nonrandom spatial genetic structure was approximately 7.0 m, suggesting that seed dispersal was limited. KINGROUP analyses showed that 44 genotype pairs were full siblings, 23 were half-siblings, and 40 were parent-offspring. Only 32 seedlings were observed, of which 15 had reproduced asexually. The number of P. japonica trees has been increasing gradually for more than half a century in our study areas.     

Genetic diversity in two threatened species in Vietnam: <Emphasis Type="Italic">Taxus chinensis</Emphasis> and <Emphasis Type="Italic">Taxus wallichiana</Emphasis>

Taxus chinensis and T. wallichiana in have been threatened in their distribution areas in recent decades because of their over-exploitation and reduction and destruction of native habitats. Determining the genetic diversity in populations of the two species will provide guidelines for their protection and preservation. Two hundred and fifteen trees from six populations of T. chinensis and 150 sampled trees of T. wallichiana were sampled. Six microsatellite primer pairs selected from 16 primer pairs were used to investigate genetic variation at the population and species levels. Five yielded polymorphic alleles, and among the 13 putative alleles amplified, 11 were polymorphic (accounting for 76.33 %).Shannon’s information index (I) and percentage of polymorphic bands (PPB) (I = 0.202 and PPB = 67.22 % for T. chinensis; I = 0.217 and PPB = 65.03 % for T. wallichiana). Both species had low levels of genetic diversity (mean H _o = 0.107, H _e = 0.121 for T. chinensis; H _o = 0.095, H _e = 0.109 for T. wallichiana). Genetic differentiation among populations was higher (F _ST = 0.189) for T. chinensis and lower (0.156) for T. wallichiana, indicating limited gene flow (Nm) among populations for T. chinensis (0.68) and T. wallichiana (0.65). Variation among individuals of T. chinensis was 63.59 and 73.12 % for T. wallichiana. Thus, the threatened status of the two conifers is related to a lack of genetic diversity. All populations are isolated in small forest remnants. An ex situ conservation site should be established with a new population for these species that comprises all the genetic groups for the best chance to improve their fitness under environmental stresses.     

Mating patterns of the gum arabic tree (<Emphasis Type="Italic">Acacia senegal synonym Senegalia senegal</Emphasis>) in two different habitats

Understanding the variation of mating patterns in disturbed habitats provide insight into the evolutionary potential of plant species and how they persist over time. However, this phenomenon is poorly understood in tropical dryland tree species. In the present study, we investigated how Acacia senegal reproduces in two different environmental contexts in Kenya. Open-pollinated progeny arrays of 10 maternal trees from each environmental context were genotyped using 12 nuclear microsatellite markers. Overall, A. senegal displayed a predominantly allogamous mating pattern. However, higher multilocus outcrossing rate (tm) was found in Lake Bogoria (tm = 1.00) than in Kampi ya Moto population (tm = 0.949). Higher biparental inbreeding (t _m  ? t _s  = 0.116) and correlation of outcrossed paternity (rp = 0.329) was found in Kampi ya Moto than in Lake Bogoria population (t _m  ? t _s  = 0.074, rp = 0.055), showing the occurrence of mating among relatives. Coefficient of coancestry (Θ = 0.208) showed that full-sibs constitute about 21% of the offspring in Kampi ya Moto population compared to about 14% (Θ = 0.136) in Lake Bogoria population. The results demonstrate that low adult tree density of A. senegal may be promoting seed production through consanguineous mating and suggest that man-made disturbance can affect mating patterns of the species. Despite these mating differences, trees from both populations can contribute as seed source for conservational plans, and to support effective genetic conservation and artificial regeneration programs of A. senegal. We suggest collection of seeds from at least 42 and 63 trees in Lake Bogoria and Kampi ya Moto populations, respectively, to retain a progeny array with a total effective population size of 150.     

Physiological regulation of poplar species to experimental warming differs between species with contrasting elevation ranges

Climate warming has resulted in rapid range shifts of plant species, but it is not well known how species with different natural distribution ranges adapt to increase in temperature through physiological adjustment. We experimentally imposed a 1.8 °C increase of air temperature to the cuttings of two common poplar species Populus yunnanensis and Populus szechuanica naturally growing in southwest China using open-top chambers. Populus yunnanensis is distributed along a narrower elevation range compared with P. szechuanica. We determined some key physiological parameters and plant growth regulator activities during the growing season without soil water limitation. Our results showed that a 1.8 °C increase in air temperature increased shoot growth of P. szechuanica through an extension of its growth period but did not affect the growth of P. yunnanensis. Malondialdehyde content, guaiacol peroxidase activities and abscisic acid content increased while indoleacetic acid content decreased in P. yunnanensis. Our results suggest that the two common poplar species in southwest China should be able to adapt to the moderate increase in temperature projected for future climate. The growth of P. szechuanica may benefit through phenological adjustment but a further increase in temperature may inhibit the growth of P. yunnanensis. For poplar plantation management, selecting species with a wide natural distribution range could provide an adaptive alternative for buffering anthropogenic induced increase in temperature and help in sustaining productivity for the long term.     

Response of nitrogen mineralization dynamics and biochemical properties to litter amendments to soils of a poplar plantation

Understanding the impact of plant litters on soil nitrogen(N) dynamics could facilitate development of management strategies that promote plantation ecosystem function.Our objective was to evaluate the effects of different litter types on N mineralization and availability,microbial biomass, and activities of L-asparaginase and odiphenol oxidase(o-DPO) in soils of a poplar(Populus deltoides) plantation through 24 weeks of incubation experiments.The tested litters included foliage(F), branch(B), or root(R) of poplar trees, and understory vegetation(U) or a mixture of F, B, and U(M).Litter amendments led to rapid N immobilization during the first 4 weeks of incubation, while net N mineralization was detected in all tested soils from 6 to 24 weeks of incubation, with zeroorder reaction rate constants(k) ranging from 7.7 to9.6 mg N released kg~(-1) soil wk~(-1).Moreover, litter addition led to increased microbial biomass carbon(C) 49–128% and increased MBC:MBN ratio by 5–92%,strengthened activities of L-asparaginase and o-DPO by14–74%; Up to about 37 kg N ha~(-1) net increase in mineralized N in litter added soils during 24 weeks of incubation suggests that adequate poplar and understory litter management could lead to reduced inputs while facilitate sustainable and economic viable plantation production.     

Identification of pests and assessment of their damage on <Emphasis Type="Italic">Carapa procera</Emphasis> and <Emphasis Type="Italic">Lophira lanceolata</Emphasis> in Burkina Faso,West Africa

Nontimber forest products are a source of income for women in rural African communities. However, these products are frequently damaged by insect pests. The present study investigates the diversity and damage rates of insect pests that attack Carapa procera seeds and Lophira lanceolata fruits. The experiment was set up in western Burkina Faso and, for C. carapa, consisted of pests collected from seeds that had fallen to the ground and from stockpiled seeds. For L. lanceolata, pests were collected from fruits on the trees, and on the ground. The collected samples were sent to the laboratory to estimate the proportion of damaged seeds/fruits and rear the insects. The results showed that Ephestia spp., Tribolium castaneum, Oryzeaphilus spp., and Tenebroides mauritanicus were the pests of Carapa procera seeds and Lophira lanceolata fruits. Ephestia spp. was recorded as the main pest of both C. procera and L. lanceolata, whereas T. castaneum was only detected from seeds of L. lanceolata. For C. procera, the stocks were the most infested (29 %) by Ephestia spp. The infestation rate of fruits of L. lanceolata by Ephestia spp. on trees (31.42 ± 3.75 %) was less than the rate of fruits by T. castaneum on the ground (44.00 ± 3.5 %). The different body sizes of Ephestia spp. may indicate the occurrence of two putative species, one from C. procera and another one from L. lanceolata. This work provides important information that could contribute to the setting up of a local-scale sustainable management framework for oil tree pests in Burkina Faso and surrounding countries.     

Two novel eukaryotic translation initiation factor 5A genes from <Emphasis Type="Italic">Populus simonii</Emphasis> × <Emphasis Type="Italic">P. nigra</Emphasis> confer tolerance to abiotic stresses in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The role of plant eIF5A proteins in multiple biological processes, such as protein synthesis regulation, translation elongation, mRNA turnover, programmed cell death and stress tolerance is well known. Toward using these powerful proteins to increase stress tolerance in agricultural plants, in the present study, we cloned and characterized PsneIF5A2 and PsneIF5A4 from young poplar (P. simonii × P. nigra) leaves. The deduced amino acid sequences of PsneIF5A2 and PsneIF5A4 were 98 % similar to each other, and they are orthologs of eIF5A1 in Arabidopsis. In a subcellular localization analysis, PsneIF5A2 and PsneIF5A4 proteins were localized in the nucleus and cytoplasm. qRT-PCR analysis showed that PsneIF5A2 and PsneIF5A4 were transcribed in poplar flowers, stem, leaves, and roots. In addition, they were also induced by abiotic stresses. Transgenic yeast expressing PsneIF5A2 and PsneIF5A4 had increased salt, heavy metal, osmotic, oxidative tolerance. Our results suggest that PsneIF5A2 and PsneIF5A4 are excellent candidates for genetic engineering to improve salt and heavy metal tolerance in agricultural plants.     

Temporal and spatial dynamics of an old-growth beech forest in western Japan

Dendrochronological approaches enable us to understand forest stand dynamics by estimation of disturbance history and age structure. The present study was conducted in an old-growth beech forest in a forest reserve in western Japan. Increment cores were taken for tree ring analysis from all canopy trees in a 50 m × 130 m study plot. Radial growth release criteria were developed to identify significant growth releases in each tree ring series and to characterize the disturbance history of the study site. The age structure of the forest was indicative of continuous establishment by Fagus crenata and simultaneous establishment by Magnolia obovata. A variety of low-intensity disturbances were identified in each decade, especially after the 1900s, but the occurrence of high-intensity catastrophic disturbance was rare, and likely played an important role in maintaining species diversity in the existing forest canopy. The results also suggest that F. crenata regenerates gradually before and after both large- and small-scale disturbances, whereas M. obovata and Betula grossa regenerate only after large-scale catastrophic disturbances.     

A novel empirical approach for determining the extension of forest development stages in temperate old-growth forests

In the analysis of old-growth forest dynamics, the continuous process of tree aging and forest structural change is split up into several distinct forest development stages. The criteria for distinguishing the stages vary among the different approaches. In most of them, vertical canopy heterogeneity is only coarsely addressed and horizontal forest structure is quantified at spatial scales far exceeding the size of conventional forest inventory plots. In order to describe and analyze the complex mosaic structure of temperate old-growth forests with objective and quantitative measures in the context of forest inventories, we propose the Development Stage Index I _DS . It employs two easily measured stand structural parameters (stem density and basal area) for quantifying the abundance of trees in three conventionally recognized tree diameter classes (premature ?<?40 cm; mature 40–70 cm; and over-mature?≥?70 cm) in plots of 500 m² size, systematically distributed in the forest. This allows quantifying the spatial extension of the Initial, Optimum and Terminal stages of forest development at plot, stand and landscape levels. Based on thorough stand structural analyses in three virgin beech (Fagus sylvatica) forests in Slovakia, we demonstrate that I _DS is a promising tool for (1) quantifying the proportion of the three stages on different scales, (2) visualizing the complex mixing of stages, and (3) analyzing dynamic changes in old-growth forest structure. We conclude that the Development Stage Index has the potential to improve the empirical foundation of forest dynamics research and to allow this discipline to proceed to more rigorous hypothesis testing.     

Assessing water use and soil water balance of planted native tree species under strong water limitations in Northern Chile

Some forest plantations with native species are established in semiarid central Chile to compensate for industrial activities such as those of mining. Two of those operational forest plantations were monitored from age 1 to 3 years-old (2014–2016). Some plant attributes and soil volumetric water content (VWC) were monitored for eight native tree species (Acacia caven, Schinus polygamus, Porlieria chilensis, Lithraea caustica, Quillaja saponaria, Cryptocarya alba, Drimys winteri and Maytenus boaria), and a water balance model fitted to assess plant water use. Site preparation comprised planting holes of 40 cm?×?40 cm by 50 cm in depth dug with a backhoe. Substrate was removed and mixed with compost in proportion 70:30 before mixing it in the planting hole. Planting holes acted as water reservoirs over the study period with soil VWC generally increasing with soil depth being also less variable deeper than in the upper soil layers. The ratio of adaxial (upper leaf side) to abaxial (lower leaf side) stomatal conductance approximately followed a species gradient from xeric to mesic. Irrigation represented about 26% and 53% of the total water input for the sclerophyll and the D. winteri plantation, respectively. At the plant level (0.4?×?0.4 m), soil evaporation and transpiration of D. winteri (273 and 232 mm year^?1, equivalent to 43.7 and 37.1 L plant^?1, respectively) were about twofold the values for the sclerophyllous/malacophyllous plantation (138 and 128 mm year^?1, 22.1 and 20.5 L plant^?1, respectively). We suggest the water budget for the sclerophyll/malacophyllous plantation was tight but feasible to be adjusted while for D. winteri irrigation was excessive, could be drastically reduced, and suppressed altogether if planted in gullies. We believe water balance models and soil moisture content sensors could be used to better plan and manage irrigation frequency and amounts in compensation forest plantations in semiarid central Chile.