Salinity stress effects on the growth, morphological, physiological, and biochemical properties of Melia (Melia dubia Cav.) plant

Salinity stress severely affects the growth, physiological and developmental processes in plant species. Melia dubia is an ecologically and economically important tree species of the Indian subcontinent. However, systematic information with respect to the species salt tolerance potential is completely lacking. Under salt stress conditions, determining suitable soil EC range is required for the better survival, growth and productivity of the tree species. In present study, we investigated the effects of different soil salinity (EC 4, 8, and 12) levels on the ion homeostasis, physio-biochemistry, morphology, and growth of M. dubia plant. Results revealed that increase in soil salinity causes higher Na+ content and Na+/K+ ratio, while lower K+ content, in the leaf tissues of M. dubia. The physiological processes such as the photosynthetic rate, stomatal conductance, internal CO2 concentration, and transpiration rate were adversely affected with the increased salt stress levels. Morphological parameters, such as internodal length, petiole length, leaf length, and leaf width also decreased (P<0.05) under saline stress conditions. Results further indicated that salinity levels significantly (P<0.05) affected the M. dubia growth, and the growth rate was found optimum upto 8 EC, thereafter it slightly decreased with the increased salt stress to 12 EC. Our findings showed that increased salinity stress causes significant changes in the physiological, morphological, and growth pattern of M. dubia. Therefore, based on present experiment, we found M. dubia suitable for the salt affected soils of EC 8 with optimum growth rate and at EC 12 with the moderate (20–25%) growth reduction.

Diversity, distribution, and threats of the Juglandaceae in Vietnam

Vietnam is one of the main centers of generic diversity for Juglandaceae worldwide. In this study, we present for the first time a province-wide distribution of all 3 subfamilies, 7 genera, and 11 Vietnamese species, and give an update on the habitats of all Vietnamese Juglandaceae species, their uses, and current threats. Juglandaceae are found throughout Vietnam. However, most species occur predominantly in the northern part of the country between 600 and 1200 m. Some taxa range is found extensively from sea level up to 2,500 meters above sea level. According to the IUCN Red List, Rhoiptelea chiliantha, Carya sinensis, and Pterocarya tonkinensis are threatened while Engelhardia spicata, E. serrata, Alfaropsis roxburghiana, Pterocarya stenoptera are classified as least concerned. Carya tonkinensis is threatened locally, and Engelhardia spicata var. colebrookiana and Platycarya strobilacea merit “threatened” designation in Vietnam’s Red Data Book. The most frequent threats are logging, land-use change, and habitat destruction due to artificial wood plantations or road construction. Until now, no conservation measures have been applied for any of the species in Vietnam, although some species occur in national parks. Our study gives an important update on the current diversity and distribution of Juglandaceae in Vietnam.We point out the need for a correct assessment of the threat status of various species on a national and international scale to protect the rarest and most endangered of them. Further research, the use of various forms of protection of individual taxa and/or their habitats, and drawing the attention of an international group of researchers to the urgent need to work together to protect biodiversity in Vietnam hot spots are necessary.

Radial variations in wood density, and their implications for above-ground biomass estimations, in a tropical high-andean forest

Wood density (WD) is a central trait to explain tree functioning, and is also an important predic­tor of tree above-ground biomass (AGB). Therefore, radial trends in WD (i.e., from pith to bark) may have important implications in understanding tree life-history variations, as well as in forest biomass and carbon estimations. The occurrence of these radial trends in WD is thought to vary among forests, particularly with canopy openness and stratification. Yet, most of the studies on this topic in tropical forests have been conducted on lowland closed-canopy forests, while very little is known about the prevalence and magnitude of these trends among trees from open-canopy forests, such as high-mountain forests. I examined radial gradients in WD and explored their implications for AGB estimations. Radial wood cores were taken with increment borers from 69 trees belonging to 18 species from a high-An­dean forest. Each wood core was cut every 1-cm, and WD was measured for every 1-cm segment. Errors in AGB estimations that resulted from not considering radial trends in WD were estimated for each tree and species. Eight out of eighteen species had significant radial trends in WD. Among these species, two species showed decreases of WD towards the bark, one species showed increments of WD from pith to bark, and five species showed U-shaped gradients (i.e., high WD near the pith and bark, and relatively low WD at inter­mediate diameters). The prevalence of U-shaped radial trends in WD may be related to the relatively open and less stratified canopy of the study forest. Not taking into account radial trends in WD led in general to under-estimations of AGB (averaging −7.66 % when using mean WD, and −5.56 % for outer WD) in most of the study species, suggesting that tropical high-Andean forests may possibly store more biomass carbon than has been previously estimated. These findings are important to expand our knowledge on wood allocation patterns during tree ontogeny, and also to improve the accuracy of biomass and carbon estimations in tropical high-Andean forests.

The effects of temperature and exogenous auxin on cutting propagation of some junipers

From past to the present, cultural, medicinal, landscape and culinary use of junipers has contrib­uted to it being one of the most widely distributed woody plants in the world. Therefore, it is so important that finding appropriate production methods to obtain quality seedlings in line with the usage area. In the present study, it was tried to determine the best conditions and applications on propagation by cuttings of three juniper taxa including Juniperus communis L. ‘Hibernica’, Juniperus chinensis L. ‘Stricta’, and Juniperus chinensis L. ‘Stricta Variegata’. For this purpose, two different greenhouse treatments (Greenhouse-1 with the air temperature at 20±2°C, rooting table temperature at 25±2°C and humidity level at 70±2%; Green­house-2 with the air temperature at 20±2°C, rooting table temperature at 20±2°C and humidity level at 70±2%) and different auxin applications (Indole-3-Butyric Acid, Indole-3-Acetic Acid and α-Naphthalene Acetic Acid at concentrations of 3000 and 5000 ppm) were designed. The highest rooting percentages were generally achieved in Greenhouse-1. IAA 5000 ppm treatment for J. communis ‘Hibernica’ (93.33%) and J. chinensis ‘Stricta’ (66.67%, also in Greenhouse-2) and IBA 3000 ppm treatment for J. chinensis ‘Stricta Var­iegata’ (60.00%) showed the best rooting results. This study, in which the best production conditions are investigated in some juniper taxa, is a guiding feature for the producers to ensure the sustainable utilization of junipers.

Predicting parameters of Weibull probability density function for diametric distributions in A. melanoxylon, E. camaldulensis, and E. nitens bioenergy plantation

Precise modeling of stand diameter distributions is required to provide accurate estimates of volume per diameter class and unit area. Therefore, it is necessary to obtain the most accurate probability density functions parameters estimates to predict stand diameter distribution in time. We evaluate two methods to estimate the parameters of the Weibull probability density function in the modeling of diameter distributions of bioenergy plantations. The methods considered a direct method of parameter prediction based on regression models (PPRM) and an indirect method of parameter recovery through the determination of percentiles (PRDP). Both methods are considered systems of linear equations and are adjusted through simultaneous estimation of parameters using stand variables. The greatest precision was obtained with PPRM. The PRDP method was not effective in the prediction of diameter distributions due to the high level of truncation of the observed distributions showing an overestimation of the distribution for the largest diameter classes. Estimated parameters of the Weibull PDF are directly related to mean height, quadratic mean diameter, and crop age; and are inversely related to stocking.

Trunks of multi-stem black poplars may have different genotypes – evidence from the Oder valley in Poland

The black poplar (Populus nigra L.) is an ecologically and economically important tree species, characteristic for floodplain forests in Europe. It is now considered to be endangered in many European countries due to the loss of its natural habitat caused by the development of river engineering and intensive land use management of riverside areas. Multi-stem specimens can be found occasionally in natural black poplar populations. The percentage of such individuals is low, although in some stands it may be over a dozen percent. The origin of multi-stem trees may be different. As a consequence, trunks being part of such a tree can have the same or different genotypes. The study aimed to find out whether all trunks of multi-stem black poplars are ramets of the same genet or if their genotypes are different, in which case they increase the gene pool of the population. We used 13 microsatellite nuclear markers to analyze the genotypes of 83 trunks belonging to 34 multi-stem black poplar trees from five natural populations from the Oder river valley in Poland. We also performed the sibship analysis of all trunks. The results showed that the trunks being part of the particular individual had distinct genotypes in five trees (14.7%). This indicates that they were formed as a result of the fusion of two genetically different individuals. The sibship analysis revealed that one multi-stem tree was represented by full-sibs. In the remaining four trees the fused trunks were not related. Nevertheless, we found three pairs of half-sibs between different trees that were distant from each other. The majority of the multi-stem trees we examined developed most probably due to the damage to the apical meristem of the main shoot of a single-stem tree. Nevertheless, some of them were indeed formed from two distinct individuals. Therefore, if a particular population consists of a small number of individuals, we recommend to study the genotypic homogeneity of each multi-stem tree.

Passerine birds supporting cross pollination in Erythrina stricta Roxb.

Erythina stricta is an ecologically important tree species in the rainforests of India and its nectar within the flowers contributes to birds’ diet and survival. Reports on the pollination of this species have not been published so far. We therefore explore the reproductive system of this tree species which has great significance to its ecosystem. Birds have an important role in the reproduction of trees through pollination particularly in tropical areas where reproductive success mostly depends on animal pollinator interactions. Study of visitation and nectar feeding behaviour of birds along with breeding system assessment of Erythina stricta. Birds visiting and foraging behaviour was observed during Erythrina stricta flowering season in an indian tropical rainforest. Reproductive system was assessed through controlled pollination experiments. Thirteen bird species were recorded visiting and foraging nectar from the flowers of Erythrina stricta. The maximum numbers of visits recorded were from the Red-vented Bulbul (Pycnonotus cafer, Pycnonotidae). The nectar feeding birds were, either (i) potential pollinator with long bills (e.g. Pycnonotus spp., Chloropsis aurifrons, and Dicrurus spp.) or (ii) nectar robbers with comparatively shorter bills (e.g. Zosterops palpebrosa, Stachyris ruficeps, Macronous gularis, Heterophasia glaciris). Controlled pollination experiments revealed high degree of cross pollination (xenogamy) and self-incompatibility in E. stricta. Birds were more frequent in early mornings and their foraging activity was also observed during evening hours; the frequency however, declined with respect to nectar availability. Long corolla tubes of E. stricta could restrict access to nectar collecting bees.

Propagation of threatened climber species Entada rheedii Spreng. – a medicinal plant with extremely thick and hard seed coat

The study explored propagation techniques of Entada rheedii Spreng., a threatened medicinal climber species with extremely hard seed coat. Propagation trials included both pre-sowing treatments of seeds for germination and clonal propagation by stem cutting. Pre-sowing treatments included (a) soaking of both cut (notched) and uncut (intact) seeds in water for 0 h, 24 h, 48 h, and 72 h and (b) immersion of intact seeds in 5% acetone solution for 5 min, 10 min, and 20 min before sowing in germination media in polybags. On the other hand, stem cutting involved treating the summer or autumn cuttings with 0%, 0.4%, and 0.8% IBA solution before rooting in non-mist propagator. Notched seeds soaked in water for 48 h showed the fastest seed germination with the highest germination percentages (73.3) and better seedling growth in terms of plant height, collar diameter, leaf number and total dry mass followed by notched seeds soaked in water for 72 h. The slowest germination and the lowest germination percentage (3.3), as well as the poorest growth performance was for intact seeds without any treatment. The highest rooting percent­age with maximum number of roots (36.6) was obtained from the summer cuttings treated with 0.4% IBA solution followed by autumn cuttings with 0.8% IBA and the lowest (43.3% and 8.3 roots) was for summer cuttings in control. The factors also dictated the survival and growth performance of rooted cuttings in the nursery conditions. The outcomes of these trials i.e., notched seeds soaking in water for 48 h will help to enhance the propagation of this valuable medicinal plant species.

Taxonomic relationships and population differentiation of the south-western Eurasian Zelkova species inferred in leaf morphology

The relict tree species Zelkova abelicea and Z. sicula (Ulmaceae) occur in Crete and Sicily, respectively. Zelkova abelicea grows in approximately 40 localities in the mountains of Crete, while Z. sicula has been found in only two stands in Sicily. We compared 25 morphological characters of the leaves of both species and used statistical methods (Tukey’stest, discrimination analysis, principal component analysis, agglomeration) to reveal the differences between these two species, their relation to Z. carpinifolia (the third Zelkova south-west Eurasian species), and between the leaves from different shoot types. Our study represents the first comparative biometric analysis of the three Zelkova species localized in the western edge of the current geographic range of the genus. We found that the species differed from each other both, in terms of leaf form characters and level of leaf variation. Zelkova carpinifolia was clearly different from Z. abelicea, while the two populations of Z. sicula, SIB and SIA, were more similar to Z. carpinifolia and Z. abelicea, respectively. The latter finding supports the results of recent molecular studies suggestingt he hybrid origin of Z. sicula. Zelkova abelicea, Z. sicula and Z. carpinifolia differ each other in the leaf characteristics and level of phenotypic variation.

Pattern of tree diversity in lowland tropical forest in Nikiwar, West Papua, Indonesia

Trees are significant components of ecosystems built by several widespread species. For instance, Papua forest is known to comprise abiotic and biotic elements. Also, certain plants have grown in popularity to a point where they are discovered almost everywhere. The purpose of this study, therefore, was to investigate tree diversity, distribution, and the importance of conservation. Data were collected in four locations using a total of 24 sample plots spread across Idoor, Karst, Persemaian, and Torembi, where seven, four, seven, and five plots were allocated, respectively. These forests formed a mixed natural plantation comprising 76 species from 35 families. Furthermore, Idoor and Karst generated the highest species diversity and varied significantly compared to Persemaian, while Torembi showed similarities with the other three locations. This condition formed three ecosystem communities across Persemaian, Karst, Idoor, and Torembi. Also, the composition of the dominant species showed variations at the seedling and sapling levels believed to structure the understory, while the pole and tree levels characterized the overstory. The total species status was described as critically endangered (CR) of two species, vulnerable (VU) of six species, least concern (LC) of 28 species, and data deficient (DD) species. Therefore, location management is advised to not only pay significant attention in terms of economic benefits but also ecological, including the provisions for ex-situ and in-situ conservation to support sustainable forest management.