Multi-stemmed Trees Research Articles

WITHDRAWN: Multiple resprouting strategies coexist after fire in southeastern Brazil cerrado trees

Many trees of the Brazilian savannah have underground organs from which they resprout after a fire, although the relationship between the presence of these organs and the presence of underground resprouts (basal resprouts and root suckers) is unclear. Other relationships may also exist between the height of underground resprouts and the presence of live aerial biomass, multi-stemness and fire impact, tree age and the presence of underground resprouts, and epicormic bud distribution and fire impact. To test all these relationships, data from 367 mature cerrado trees subject to a single prescribed burn in southeastern Brazil were analysed. There was no clear relationship between the presence of underground organs and the presence of underground resprouts, although fire impact strongly influenced the presence of basal resprouts, with 90% of topkilled trees presenting basal resprouts, and this strong influence may have concealed a potential relationship between the presence of underground organs and resprouts. Underground resprouts were 45% taller when trees lacked live aerial biomass because more ground-level sunlight was available for these resprouts to grow. Single-stemmed trees had on average more basal resprouts than multi-stemmed trees, which concerned the translocation of carbohydrate reserves in multi-stemmed trees to maintain the fitness of multiple stems, while single-stemmed trees could store more reserves in their underground organs. However, multi-stemmed trees were more likely than single-stemmed trees to remain unburnt, an effect of less sunlight reaching the ground, suppressing grass cover. Trees >13 years resprouted basally less often since, as the trees were not burnt frequently, they developed deeper roots instead of investing in underground buds. Epicormic bud density was highest in medium fire impacts because a high fire impact led to topkill, while a low fire impact was insufficient to break epicormic bud dormancy. Moreover, the position of the lowest and highest epicormic buds was determined by epicormic bud density, suggesting that, at medium fire impacts, there was greater mobilisation of reserves along the tree stem to activate more epicormic buds.

Mesquites Limit Targeted Grazing Effects on Texas Wintergrass Growth and Reproduction Responses

In mixed C3/C4 grasslands of the southern Great Plains of North America, honey mesquite (Prosopis glandulosa Torr.) invasion facilitates the dominance of the C3 midgrass Texas wintergrass (Nassella leucotricha [Trin. & Rupr.] Pohl) to the detriment of warm-season grasses. Little is known about the viability of targeted grazing as a treatment method for reducing Texas wintergrass biomass and reproduction, particularly under mesquite canopies. We quantified the effects of targeted grazing treatments (grazed once [G1], grazed twice [G2], and control) and mesquite canopy position (under canopy [UC] and outside of canopy [OC]) on Texas wintergrass basal area, total dry matter (DMY) per basal area, live DMY per basal area, dead DMY per basal area, leaf length, total number of reproductive culms per plant, number of fungus-infected reproductive culms per plant, and rate of reproductive culm development over 2 yr at two study sites. Targeted grazing reduced leaf length and biomass and slowed reproductive development of the wintergrass plants that cattle could more easily access. Environmental factors and differences in mesquite physiognomy at the two study sites likely interacted with grazing treatments, making it challenging to separate the impacts of targeted grazing treatments from other factors. Results suggest mesquite removal is likely necessary to increase cattle access to Texas wintergrass, particularly in stands with multistemmed trees.

Multi-stemming enhances tree survival and growth in Borneo’s logged forests

Multi-stemmed architecture is a common but overlooked tree growth form in tropical rainforests. Although multi-stemming is thought to be a key trait for tree persistence after disturbance, the role of multi-stemmed trees in post-disturbance demographic processes has been largely unexplored in logged rainforests. Here, we used decade-long measurements on nearly 14,000 tree stems to study post-logging growth and survival along a logging disturbance gradient in Malaysian Borneo. We found that multi-stemming enhanced tree persistence after logging. Along the entire disturbance gradient, multi-stemmed trees suffered significantly lower mortality than single-stemmed trees, and survival strongly increased with the number of stems. Small to medium-sized trees with multiple stems showed greater growth than similar-sized single-stemmed trees, with the difference increasing as the disturbance increased. Our findings demonstrate the significance of multi-stemmed architecture after logging in Borneo’s rainforests and highlight the need to consider the multi-stemmed growth form in forest inventories and models of post-disturbance forest dynamics.

Scaling up uncertainties in allometric models: How to see the forest, not the trees

Quantifying uncertainty in forest assessments is challenging because of the number of sources of error and the many possible approaches to quantify and propagate them. The uncertainty in allometric equations has sometimes been represented by propagating uncertainty only in the prediction of individuals, but at large scales with large numbers of trees uncertainty in model fit is more important than uncertainty in individuals. We compared four different approaches to representing model uncertainty: a formula for the confidence interval, Monte Carlo sampling of the slope and intercept of the regression, bootstrap resampling of the allometric data, and a Bayesian approach. We applied these approaches to propagating model uncertainty at four different scales of tree inventory (10 to 10,000 trees) for four study sites with varying allometry and model fit statistics, ranging from a monocultural plantation to a multi-species shrubland with multi-stemmed trees. We found that the four approaches to quantifying uncertainty in model fit were in good agreement, except that bootstrapping resulted in higher uncertainty at the site with the fewest trees in the allometric data set (48), because outliers could be represented multiple times or not at all in each sample. The uncertainty in model fit did not vary with the number of trees in the inventory to which it was applied. In contrast, the uncertainty in predicting individuals was higher than model fit uncertainty when applied to small numbers of trees, but became negligible with 10,000 trees. The importance of this uncertainty source varied with the forest type, being largest for the shrubland, where the model fit was most poor. Low uncertainties were observed where model fit was high, as was the case in the monoculture plantation and in the subtropical jungle where hundreds of trees contributed to the allometric model. In all cases, propagating uncertainty only in the prediction of individuals would underestimate allometric uncertainty. It will always be most correct to include both uncertainty in predicting individuals and uncertainty in model fit, but when large numbers of individuals are involved, as in the case of national forest inventories, the contribution of uncertainty in predicting individuals can be ignored. When the number of trees is small, as may be the case in forest manipulation studies, both sources of allometric uncertainty are likely important and should be accounted for.

Selection of a breeding source material in the collection of the walnut <i>(Juglans regia L.)</i> of the Main Botanical Garden RAS

The article considers the possibility of walnut cultivation in the Moscow region - in conditions far from its ecological optimum. The studies were carried out in 2013-2021 on the experimental site of the department of flora of the Main Botanical Garden of RAS, where in 1977 Alexei Konstantinovich Skvortsov established a collection of walnuts. The material for planting was the seed progeny of varieties and forms from various cities, including Moscow. The purpose of this work was the selection of promising forms for the creation of varieties adapted to the conditions of central Russia. The criteria for selecting the best genotypes were: winter hardiness, frost resistance, precocity, earlier entry into fruiting, autogamous type of flowering, lateral type of fruiting, fruits in the clusters, restraint in growth and high commercial qualities of fruits. As a result of the phenological observations, it was revealed that acclimatized walnut plants go through a full cycle of seasonal development, start the growing season late (April 29 − May 6) and end it early (October 1−11). The shoots are completely woody before the onset of cold weather, so the plants are quite winter-hardy in ordinary mild winters. The critical temperature in Moscow was -29.9 °C in January 2017. Low temperatures caused the death of reproductive buds, annual and perennial wood in almost all trees, and the most weakened specimens fell out completely. To date, the walnut gene pool is represented by 87 specimens aged from 37 to 44 years, of which 47 are single-stemmed and multi-stemmed trees and 40 are bushes. Samples were noted that, after the winter of 2017, normally bloomed and formed single fruits, despite the fact that the summer of 2017 was the coldest in the 21st century. As a result of studying the created genetic collection, 12 promising forms were identified. They are characterized by the presence of several breeding-valuable traits and regularly bear fruit. Further vegetative reproduction and varietal testing of the selected material is planned, which will allow solving a number of breeding and production problems to create a local range of walnuts.

Multi-Stemmed Habit in Trees Contributes Climate Resilience in Tropical Dry Forest

Understanding how environmental adaptations mediate plant and ecosystem responses becomes increasingly important under accelerating global environmental change. Multi-stemmed trees, for example, differ in form and function from single-stemmed trees and may possess physiological advantages that allow for persistence during stressful climatic events such as extended drought. Following the worst drought in Hawaii in a century, we examined patterns of stem abundance and turnover in a Hawaiian lowland dry forest (LDF) and a montane wet forest (MWF) to investigate how multi-stemmed trees might influence site persistence, and how stem abundance and turnover relate to key functional traits. We found stem abundance and multi-stemmed trees to be an important component for climate resilience within the LDF. The LDF had higher relative abundance of multi-stemmed trees, stem abundance, and mean stem abundance compared to a reference MWF. Within the LDF, multi-stemmed trees had higher relative stem abundance (i.e., percent composition of stems to the total number of stems in the LDF) and higher estimated aboveground carbon than single-stemmed trees. Stem abundance varied among species and tree size classes. Stem turnover (i.e., change in stem abundance between five-year censuses) varied among species and tree size classes and species mean stem turnover was correlated with mean species stem abundance per tree. At the plot level, stem abundance per tree is also a predictor of survival, though mortality did not differ between multiple- and single-stemmed trees. Lastly, species with higher mean stem abundance per tree tended to have traits associated with a higher light-saturated photosynthetic rate, suggesting greater productivity in periods with higher water supply. Identifying the traits that allow species and forest communities to persist in dry environments or respond to disturbance is useful for forecasting ecological climate resilience or potential for restoration in tropical dry forests.

Diversity of the hybrid forms between Siberian stone pine and Siberian dwarf pine

Siberian stone pine (Pinus sibirica) and Siberian dwarf pine (P. pumila) are Russian five-needle pines withdifferent life forms, namely upright tree and prostrate tree, respectively. Hybridization of the species was considered in thepaper from the point of view of the habitus of their natural hybrids. In early studies, it was always noted that the hybridswere intermediate in comparison with the parental species. Crown structure in hybrids are largely determined by twomain factors. These are deflection of the tree stem from the vertical axis and the selectivity of apical dominance. Hybridsgrowing in open places under full lighting conditions are characterized by strictly intermediate growth form. In a forestwhere there is no enough light, hybrid reaches for sun but gradually deviates to the side, which ultimately leads to a branchbreak or even the roots of the entire tree being upturned from the soil. In the mountains, hybrids can form uniform trunkbranches, forming a cup-shaped crown, similar to how it happens in Siberian dwarf pine. Thus, the previously notedintermediate morphology of hybrids represents a series of forms, from almost vertical multi-stemmed trees to pumila-likeones with a cup-shaped crown.

Different heights of resprouting by trees: Response to small-scale environmental restrictions in a non-fire-prone Caatinga tropical dry forest

Resprouting is an ecological strategy widely adopted by trees in response to different restrictive factors, in which the stems can be emitted at different heights of the tree. Although the patterns of resprouting height are already known in response to some restrictive factors (such as fire), their occurrence is not well elucidated in non-fire prone dry environments where continuous resource restriction may stimulate resprouting. Here, we assessed the general ecological dominance of resprouting trees in the community and the ecological dominance of trees resprouting at different heights in response to environmental restrictions in a tropical dry forest (TDF). We used multi-stemmed trees as a proxy for resprouting in response to the local restrictive factors. Our hypotheses were: i) resprouting trees have greater ecological dominance (more trees and stems and higher biomass) in more restrictive plots; ii) the ecological dominance of lower-height resprouting trees is greater in more restrictive plots, while the dominance of upper-height resprouting trees is greater in less restrictive plots. For this, we used a dataset of 27 TDF plots where we measured and identified the trees that met the inclusion criterion (3 cm of diameter at breast height) and collected soil samples to gather data on environmental restriction. Multi-stemmed trees were classified according to the height of additional-stem emission (below-ground, ground-level, and above-ground), considering the bottom-most stem originating from the main stem. We then evaluated whether the ecological dominance of resprouting trees and trees with different resprouting heights varied significantly in response to environmental restrictiveness, and patterns of species composition in the height categories. We found a greater dominance of resprouting trees in more restrictive environments, with lower-height resprouting trees dominating the most restrictive plots (two hypotheses confirmed). This finding may be associated with physiological mechanisms of drought response because resprouting height is directly associated with the level of damage inflicted on the internal structure of trees. We also found that the species varied in their ability for stem emission at different heights, whereby the most plastic species were more dominant compared to those with just one height of emission. This finding indicates that different restrictive factors can produce similar resprouting expressions, reinforcing the need to advance the knowledge on the importance of resprouting in TDF.

Multi-stemming strategies of Quercus glauca in an evergreen broad-leaved forest: when and where

Abstract Aims Multi-stemming supports plants’ resilience to disturbances and then contributes to soil stabilization and forest function, especially in mountain habitats. Many questions remain about (i) the ontogenetic phase at which multiple stems can occur, (ii) how habitat drivers affect multi-stemming and (iii) whether ontogenetic phase and habitat drivers interact. We asked these questions for Quercus glauca (ring-cupped oak), the dominant species and sprouter across large warm-temperate areas of Asia; its multi-stemmed trees reflect individual survival, population regeneration and forest ecosystem stability. Methods In a 5-ha permanent plot of subtropical evergreen broad-leaved forest in eastern China, we examined the temporal patterns and spatial distribution of multi-stemmed trees of Q. glauca within 99 quadrats of 20 m × 20 m. Important Findings There were three temporal modes for multi-stemming among the Q. glauca trees and most of them appeared to produce multiple stems from an early stage. Environmental disturbances related to slope convexity appear to be the main drivers of multi-stemming of Q. glauca. Moreover, the closer to the ridge, the earlier the multi-stemming occurs. Thus, also for other woody species in other forests and climate zones, ontogeny and environmental drivers promoting disturbance (not only geomorphology, but also extreme weather events, soil drought, fire), as well as soil fertility, need to be considered in combination to better understand multi-stemming and its consequences for community structure.

Traditional Pollarding Practices for Dimorphic Ash Tree (Fraxinus dimorpha) Support Soil Fertility in the Moroccan High Atlas

Shaping and pollarding of dimorphic ash tree (Fraxinus dimorpha) are two traditional practices used by the local inhabitants in agropastoral parklands of the Moroccan High Atlas to secure their production systems and increase tree production and strength. This study focused on assessing the impact of these practices on soil quality. Abiotic parameters and mycorrhizal attributes of the samples of four soil types related to different ash tree morphotypes were assessed and compared. Rhizospheric soils (Rs) of three F. dimorpha morphotypes were sampled: trees regularly pollarded and shaped for stem anastomosis (An), regularly pollarded multistemmed trees (Na), and multistemmed trees belonging to a public forest under national forestry service management and sporadically illegally pollarded (Fo). The fourth soil was a non-Rs found in bare soils, which represented the control (Nr). Results showed a sizable difference between An soil properties and the other soil types ones, with significantly higher phosphorus (×6), nitrogen (×5), and carbon (×2) levels and higher mycorrhizal (×6) status than Nr soil, and showed 37% more mycorrhization intensity than Fo. Na showed intermediary levels between An and Fo. Fo had ×2 P, ×3 Total Kjeldahl Nitrogen (TKN), 58% more Total Organic Carbon (TOC) content, and twice the spore density compared with Nr. It is concluded that shaping and pollarding have a positive impact on the soil characteristics of the studied species and could make a useful contribution to sound agroforest management schemes.

How do social status and tree architecture influence radial growth, wood density and drought response in spontaneously established oak forests?

During the past decades, a multitude of oak stands have spontaneously established across the pine-dominated landscapes of the French Landes de Gascogne. Yet their future performance under modern climate change is unknown. We show that coppiced, dominant trees are most prepared to cope with drought episodes, displaying higher basal area increment and lower sensitivity to extreme events. Forest stands dominated by pedunculate oak (Quercus robur L.) have spontaneously established across the pine-dominated landscapes of the French Landes de Gascogne. These oak stands are typically unmanaged and unsystematically coppiced, resulting in mixtures of single- and multi-stemmed (coppiced) trees. To determine the ability of spontaneous oak forest stands to face climate change–related hazards, by analysing differences in growth (tree-ring width and basal area increment—BAI), wood density and climate sensitivity depending on their tree architecture (single- vs multi-stemmed trees) and their social status in the forest. We exhaustively cored 15 oak stands (n = 657 trees). We compared stand characteristics and climate sensitivity between tree architectures considering two sampling designs, either all sampled trees (the exhaustive sampling) or those with a dominant status (dominant sampling). At the tree level, we used linear mixed effects models to compare wood density and growth between tree architectures and the trees’ social status within the canopy layer (dominant- vs non-dominant trees). Multi-stemmed trees exhibited higher wood density than single-stemmed trees for diameters > 30 cm. Dominant multi-stemmed trees showed lower sensitivity to extreme events (pointer years), higher BAI but lower annual growth rates than dominant single-stemmed trees. Dominant multi-stemmed trees are potentially the most prepared ones to cope with increasing soil water deficit following drought episodes, at least during the first 60 years of the life of the tree. The vulnerability to face harsher climate conditions for Q. robur stands can be misled when using a dominant sampling design.

Effective determination of biomass in oak coppices

The diameter at breast height of the largest sprout per coppiced stool proved to be accurate for the total sprout biomass estimates at stand level. Traditional coppicing is one of the oldest silvicultural systems for biomass production. However, a quick and simple biomass estimate methodology across the entire growth period is lacking. The objective of this study was to find the sprout parameters that need to be measured for accurate sprout estimates as well as to find a necessary minimum number of sprouts for these estimates. Using data from 20 sample Turkey oak multi-stem trees, we modelled sprout biomass as a function of an increasing number of sprouts in interaction with different sprout parameters in a later post-resprouting period. Results showed that the DBH of only two of the largest sprouts per stump proved to be accurate estimators of the total sprout biomass of the individual stool. For sprout biomass estimates at stand level, we recommend measuring the DBH of the largest sprout within each stool in a plot and then calculating and summing the estimated sprout biomasses of the individual stools. This study illustrates that the biomass can simply be estimated by easily measured parameters of sprouts; therefore, the multi-stemmed trees can be easily included into the yield or ecosystem studies of woody vegetation with less time-consuming measurements.

Identifying the best plant water status indicator for bio‐energy poplar genotypes

AbstractThis contribution provides better insights in the water relations and the physiological traits of four commercial poplar genotypes of different genetic background, 'Bakan', 'Oudenberg', 'Koster' and 'Grimminge'. The main continuous (nondestructive and providing continuous and automated data records) and discontinuous (destructive and not allowing automation) plant water status (PWS) indicators were monitored at a multigenotype, commercial‐scale short‐rotation coppice plantation in East‐Flanders (Belgium), and their relationships with the principal environmental variables were assessed. All measurements were performed during the entire 2016 growing season on the third year of the third rotation in multistemmed trees. The discontinuous PWS indicators were measured on 10 separate days with a different evaporative demand and soil water content, while the continuous PWS indicators were recorded from April to November. The genotypes responded differently to environmental drivers and to soil conditions, based on the PWS indicators, featuring a different water behaviour in relation to the level of isohydricity. Poplar genotypes 'Koster' and 'Bakan' showed the typical water‐conserving behaviour of isohydric species, while 'Grimminge' was more in line with the anisohydric ones. A principal component analysis showed that sap flow (Fs) was the most suitable PWS indicator. The Fs and therefore the sap flow‐based canopy transpiration (Ec) were tightly linked to the phenological stage of the trees as well as to vapour pressure deficit and photosynthetic photon flux density, based on relationships between Ec and environmental variables. A quantitative predictive model was developed to estimate the crop water requirements for specific genotypes, by calculating transpiration per unit of ground area with a few environmental variables, monitored with easy‐to‐handle sensors.

How should we measure the DBH of multi-stemmed urban trees?

Foresters use diameter at breast height (DBH) to estimate timber volumes, quantify ecosystem services, and predict other biometrics that would be difficult to directly measure. But DBH has numerous problems, including a range of “breast heights” and challenges with applying this standard to divergent tree forms. Our study focuses on street trees that fork between 30 and 137 cm of height (hereafter “multi-stemmed trees”), which researchers have identified as particularly challenging in the ongoing development of urban allometric models, as well as consistency in measurements across space and time. Using a mixed methods approach, we surveyed 25 urban forestry practitioners in twelve cities in the northeastern United States (US) about the measurement and management of multi-stemmed street trees, and intensively measured 569 trees of three frequently planted and commonly multi-stemmed genera (Malus, Prunus, and Zelkova) in Philadelphia, PA, US. Specifically, we measured stem diameter at several distances above the ground: at the root collar, at 30 cm, just below the fork (which occurred between 30 and 137 cm), and at 137 cm (up to six stems following established protocols). Survey responses indicated that current mensuration practices are burdensome, that practitioners employ alternatives to the current protocols for measuring at 137 cm, and that small-statured, frequently multi-stemmed trees are an increasing proportion of street tree populations. Analysis of field data did not find substantial differences between methods of measurement with regard to predictive power for total height and average crown width. Alternatives to the current protocols for measuring at 137 cm have other advantages, including time required, ease of measurement, simplicity, and capacity to compare measurements between trees and over time. For trees that fork between 30 and 137 cm, we recommend taking a single diameter measurement at a lower height—either just below the fork or at 30 cm. Diameter measurements at 30 cm better serve researchers seeking to consistently measure radial growth over time, whereas diameter below the fork may suit practitioners who do not need fine resolution in trunk measurements.

Weak Apical Control of Swiss Stone Pine (Pinus cembra L.) May Serve as a Protection against Environmental Stress above Treeline in the Central European Alps

At the treeline in the Central European Alps, adverse climate conditions impair tree growth and cause krummholz formation of Swiss stone pine (Pinus cembra L.). Multi-stemmed trees (tree clusters) are frequently found in the treeline ecotone and are generally thought to originate from seed caches (multiple genets) of the European nutcracker (N. caryocatactes) or due to repeated damage of the leader shoot by browsing or mechanical stress (single genet). Additionally, lack of apical control can lead to upward bending of lateral branches, which may obscure single-genet origin if the lower branching points are overgrown by vegetation and the humus layer. The multi-stemmed growth form may serve as a means of protection against extreme environmental stress during winter, especially at wind-exposed sites, because leeward shoots are protected from, e.g., ice particle abrasion and winter desiccation. The aims of this study therefore were to analyze in an extensive field survey: (i) whether weak apical control may serve as a protection against winter stress; and (ii) to what extent the multi-stemmed growth form of P. cembra in the krummholz zone is originating from a single genet or multiple genets. To accomplish this, the growth habit of P. cembra saplings was determined in areas showing extensive needle damage caused by winter stress. Multi-stemmed saplings were assigned to single and multiple genets based on determination of existing branching points below the soil surface. The findings revealed that upward bending of lateral branches could protect saplings against winter stress factors, and, although multi-stemmed P. cembra trees were primarily found to originate from multiple genets (most likely seed caches), about 38% of tree clusters originated from upward bending of (partially) buried branches. The results suggest that weak apical control of P. cembra in the sapling stage might be an adaptation to increase survival rate under severe climate conditions prevailing above treeline during winter.

Phenology and yield evaluation of hazelnut cultivars in Latium region

In central Italy (Latium), hazelnut cultivation is carried out using only a few round-shaped nut producing cultivars including ‘Tonda Gentile Romana’, ‘Tonda di Giffoni’ and ‘Nocchione’ as main pollinizer. With the aim to extend the hazelnut genetic base a variety collection was established in a typical hazelnut-growing area of Viterbo province. The collection consists of 48 cultivars, each represented by three multi-stemmed trees. Flowering time, female and male full bloom, leaf budbreak, and leaf fall of each cultivar were recorded over three years (2014-2016). Sucker production and vigor of the trees were also measured. Further, nut yield and nut and kernel traits were investigated. On average, ‘Tonda Rossa’, ‘Karidaty’, ‘Sivri A’ and ‘Tonda Gentile delle Langhe’ showed a very early period of pollen shed, which was concentrated in the middle of December. In respect to female bloom, the earliest female bloom was in ‘Nostrale’, ‘San Giovanni’ and ‘Tonda di Giffoni’, which showed style emergence (red-dot stage) at the end of November. ‘San Giovanni’ and ‘Tonda di Giffoni’ also showed an early leaf budbreak, which occurred in mid-February, and this early vegetative growth could make this cultivar vulnerable to frost injury. ‘Camponica’ showed the highest yield over the period of investigation, and ‘Nociara’ showed the highest yield efficiency.

Characterization of natural provenances of Acacia mangium Willd. and Acacia auriculiformis A. Cunn. ex Benth. in Malaysia based on phenotypic traits

Acacia mangium Willdenow and Acacia auriculiformis A. Cunningham ex Bentham and their hybrid have become important planting species in Malaysia. Due to their high demand and consumption, development of high quality planting materials is desired. Conventional breeding of Acacia Miller is slow but the utilization of marker-assisted selection breeding can expedite the breeding process. Markers associated with quantitative trait loci (QTLs) required pedigreed populations whereas association mapping can be used directly on diverse germplasm. This study was conducted to screen provenances of A. mangium and A. auriculiformis of different geographical origins for their performance under the Malaysian environment. A. mangium exhibited superior traits compared to A. auriculiformis. More trait variation was observed within and between provenances of A. auriculiformis. Provenances from Queensland (QLD) were superior to those from Papua New Guinea (PNG) and Northern Territory. The best performing provenance with all three superior traits was from Claude River QTL of A. mangium and the worst was Bensbach Western Province, PNG belonging to A. auriculiformis. For individual traits like DBH, Morehead, PNG was superior. For plant height, Morehead, PNG was the superior provenance for A. mangium and Morehead River, QLD was from A. auriculiformis. For stem straightness the A. auriculiformis provenance Jardines Garden, QTL was superior to West of Morehead (PNG) for A. mangium. Multivariate analysis grouped provenances together based on similar traits and genetic similarity. These provenances can be used for seed families which can be treated as a homogeneous population for association mapping or for the development of segregating hybrid populations for Acacia breeding. For the purpose of utilization, provenances of A. mangium can be used for sawn timber. For fuelwood and charcoal industries, A. auriculiformis provenances should be preferred by selecting multi-stemmed trees. The most variable provenances with superior phenotypic traits can be integrated with the genotypic data e.g. single nucleotide polymorphism markers for association mapping to identify quantitative trait loci for marker-assisted breeding.

Diferencias en el hábito de crecimiento como variable explicativa de la influencia climática en Prosopis flexuosa en el Desierto del Monte Central (Argentina).

Los métodos dendroclimatológicos representan una de las herramientas más valiosas para analizar la influencia del clima sobre la dinámica del incremento radial y la morfología de las plantas leñosas. En el Desierto del Monte Central, Prosopis flexuosa DC (algarrobo dulce), crece como árbol uni-fustal pero también como multi-fustal. Investigaciones anteriores han evidenciado la utilidad del ancho de anillo de esta especie como registro de eventos climáticos. Sin embargo, estas investigaciones han diferido metodológicamente, considerando o descartando los individuos multi-fustales. Este trabajo analizó si la variabilidad en el hábito de crecimiento expresa diferencias en la señal dendroclimática del algarrobo dulce. Dos cronologías de ancho de anillos, una derivada de individuos uni-fustales (UF) y otra de multi-fustales (MF) presentes en un mismo ambiente ecológico fueron desarrolladas. Se observó que hay una mayor sensibilidad de la cronología MF respecto de la UF en relación a la incidencia en el crecimiento de eventos climáticos extremos y del clima en general en el largo plazo. Esto sugiere que los individuos multi-fustales constituyen una buena representación de la variabilidad del clima local. Debido a la gran extensión territorial de especie, otros estudios que abarquen la extensión geográfica de P. flexuosa son deseables para profundizar los resultados logrados.

Tree Density and Forest Productivity in a Heterogeneous Alpine Environment: Insights from Airborne Laser Scanning and Imaging Spectroscopy

We outline an approach combining airborne laser scanning (ALS) and imaging spectroscopy (IS) to quantify and assess patterns of tree density (TD) and forest productivity (FP) in a protected heterogeneous alpine forest in the Swiss National Park (SNP). We use ALS data and a local maxima (LM) approach to predict TD, as well as IS data (Airborne Prism Experiment—APEX) and an empirical model to estimate FP. We investigate the dependency of TD and FP on site related factors, in particular on surface exposition and elevation. Based on reference data (i.e., 1598 trees measured in 35 field plots), we observed an underestimation of ALS-based TD estimates of 40%. Our results suggest a limited sensitivity of the ALS approach to small trees as well as a dependency of TD estimates on canopy heterogeneity, structure, and species composition. We found a weak to moderate relationship between surface elevation and TD (R2 = 0.18–0.69) and a less pronounced trend with FP (R2 = 0.0–0.56), suggesting that both variables depend on gradients of resource availability. Further to the limitations faced in the sensitivity of the applied approaches, we conclude that the combined application of ALS and IS data was convenient for estimating tree density and mapping FP in north-facing forested areas, however, the accuracy was lower in south-facing forested areas covered with multi-stemmed trees.

Investigating niche partitioning of ectomycorrhizal fungi in specialized rooting zones of the monodominant leguminous tree Dicymbe corymbosa.

Temperate ectomycorrhizal (ECM) fungi show segregation whereby some species dominate in organic layers and others favor mineral soils. Weak layering in tropical soils is hypothesized to decrease niche space and therefore reduce the diversity of ectomycorrhizal fungi. The Neotropical ECM tree Dicymbe corymbosa forms monodominant stands and has a distinct physiognomy with vertical crown development, adventitious roots and massive root mounds, leading to multi-stemmed trees with spatially segregated rooting environments: aerial litter caches, aerial decayed wood, organic root mounds and mineral soil. We hypothesized that these microhabitats host distinct fungal assemblages and therefore promote diversity. To test our hypothesis, we sampled D.corymbosa ectomycorrhizal root tips from the four microhabitats and analyzed community composition based on pyrosequencing of fungal internal transcribed spacer (ITS) barcode markers. Several dominant fungi were ubiquitous but analyses nonetheless suggested that communities in mineral soil samples were statistically distinct from communities in organic microhabitats. These data indicate that distinctive rooting zones of D.corymbosa contribute to spatial segregation of the fungal community and likely enhance fungal diversity.