Endemic Tree Research Articles

Characterization of Two AGL6–Like Genes from a Chinese Endemic Woody Tree, Manglietia patungensis (Magnoliaceae) Provides Insight into Perianth Development and Evolution in Basal Angiosperms

Manglietia patungensis (Magnoliaceae) exhibits radially symmetric flowers with perianth consisting of three separate sepaloid tepals in whorl 1 and six petaloid tepals in the inner two whorls, which shows an obvious difference from flowers of most Magnoliaceae species that contain three uniform petaloid tepals whorls, and make it an excellent model for understanding perianth morphology differentiation during early flower evolution. Here, two AGL6 orthologs, MapaAGL6-1 and MapaAGL6-2, were isolated from M. patungensis. Sequence alignment and phylogenetic analyses grouped both genes into the AGL6 lineage. MapaAGL6-1 is expressed only in the perianth whorls, while MapaAGL6-2 is strongly expressed in the perianth whorls but is lowly expressed in gynoecium. Furthermore, ectopic expression of MapaAGL6-1 results in strong complementation phenotypes in the Arabidopsis ap1-10 flower and production of normal floral organs in four floral whorls only with the petal number reduced in whorl 2, while ectopic expression of MapaAGL6-2 only results in petals partly rescued but failing to terminate carpelloid development in Arabidopsis ap1-10 mutant. In addition, the daughter lines generated from a cross between 35S::MapaAGL6-1 transgenic plants showing strong phenotypes and 35S::MapaAGL6-2 transgenic plants showing phenotypic changes produce normal flowers. Our results suggest that MapaAGL6-1 is a reasonable A-function gene controlling perianth identity in Magnoliaceae, which infers from its expression region and complementation phenotypes in Arabidopsis ap1 mutant, while MapaAGL6-2 is mainly involved in petaloid tepal development. Our data also provide a new clue to uncover the perianth development and early evolution in basal angiosperms.

Diurnal Serianthes nelsonii Merr. leaflet paraheliotropism reduces leaflet temperature, relieves photoinhibition, and alters nyctinastic behavior

The diel cycle of Serianthes nelsonii leaflet movements was characterized under four levels of shade from full sun to 22% sunlight transmission to determine the photoprotective components of diurnal leaflet movements and the relationship to patterns of nocturnal leaflet movements. Treatments also included negating paraheliotropism by re-orienting plants every 15min throughout the photoperiod such that the plants never experienced a predictable solar vector. The timing of leaflet closure to avoid high light, the shape of the diurnal curve depicting leaflet angle, and the maximum extent of leaflet closure were influenced by the shade treatments. Protection of leaf function by paraheliotropism was also influenced by shade treatment, with the full sun plants exhibiting the greatest level of protection. Leaflet heat gain was reduced 50% by leaflet movement as determined by direct measurements of leaf-to-air temperature differences. Midday quantum efficiency of photosystem II was increased 120% by leaflet movement as determined by direct measurements of pulse modulated chlorophyll fluorescence. The extent of nyctinastic leaflet closure was greatest in the high light plants that moved the most midday and least in the shaded plants that moved the least midday, indicating the extent of diurnal paraheliotropism controlled the amplitude of nocturnal leaflet movement. Serianthes nelsonii is highly skilled at using movement to reduce leaflet exposure to the solar vector, providing instantaneous behavioral control over heat gain and photoinhibition. This case study of an endemic tree species in Micronesia has added to the nascent field of conservation physiology, and indicated that heliotropism of S. nelsonii leaves may provide the species with the ability to minimize high light damage during increased temperatures associated with climate change.

Taxonomic and functional diversity of insect herbivore assemblages associated with the canopy-dominant trees of the Azorean native forest.

Oceanic islands have been providing important insights on the structuring of ecological communities and, under the context of the present biodiversity crisis, they are paramount to assess the effects of biological invasions on community assembly. In this study we compare the taxonomic and functional diversity of insect herbivore assemblages associated with the dominant tree species of Azorean native forests and investigate the ecological processes that may have originated current patterns of plant-herbivore associations. Five dominant trees—Erica azorica, Ilex perado subsp. azorica, Juniperus brevifolia, Laurus azorica and Vaccinium cylindraceum—were sampled in the remnants of the native forest of Terceira Island (Azores) using a standardised methodology. The taxonomic and functional diversity of insect herbivore assemblages was assessed using complementary metrics and beta diversity partitioning analysis (species replacement and richness differences) aiming to evaluate the variation in insect herbivore assemblages within and between the study plant species. Sixty two insect species, mostly bugs (Hemiptera) and caterpillars (Lepidoptera), were found in the five study plants with indigenous (endemic and native non-endemic) insects occurring with higher species richness and abundance than introduced ones. Species replacement was the most important component of insect herbivore taxonomic beta diversity while differences in trait richness played a major role on functional beta diversity. The endemic E. azorica stands out from the other study plants by having associated a very distinct insect herbivore assemblage with a particular set of functional attributes, mainly composed by large bodied and long shaped species that feed by chewing. Despite the progressive biotic homogenization witnessed in the Azores during the last few decades, several strong associations between the endemic trees and their indigenous insect herbivores remain.

The complete chloroplast genome of Osmanthus serrulatus rehd., a natural sweet olive endemic to China

Osmanthus serrulatus is an endemic tree in southwest China. Here, the complete chloroplast genome of this species was assembled and characterised from high-throughput data. The entire circular genome of O. serrulatus was 155,465 bp in size, which composed of large single-copy (LSC) and small single-copy (SSC) regions of 86,545 bp and 17,494 bp, respectively, and separated by a pair of inverted repeat (IR) regions of 25,713 bp each. The genome contained 133 genes, including 88 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The overall GC content of the genome is 37.8%. A phylogenetic tree reconstructed by 35 chloroplast genomes reveals that O. serrulatus is most related with O. yunnanensis.

Characterization of the complete plastid genome of Acer tsinglingense, an endemic tree species in China

Acer tsinglingense is an ecologically and economically important tree species in China. In this study, we characterized its whole plastid genome sequence using the Illumina sequencing platform. The complete plastid genome size of A. tsinglingense is 156,039 bp in length, including a large single-copy [LSC] region of 85,760 bp, a small single-copy [SSC] region of 18,139 bp, and a pair of inverted repeats [IRs] of 26,070 bp. The genome contains 137 genes, including 89 protein-coding genes, 40 tRNA genes, and 8 rRNA genes. The GC contents in chloroplast genome, LSC region, SSC region, and IR region were 38.0%, 36.2%, 32.4%, and 42.9%, respectively. The phylogenetic analysis based on the plastid genomes showed that A. tsinglingense was more closely related with the congeneric A. laevigatum, A. palmatum, A. wilsonii, and A. buergerianum, these species were clustered into a monophyletic clade with high bootstrap support.

The complete chloroplast genome sequence of Melliodendron wangianum (Styracaceae)

Melliodendron wangianum Hu (Styracaceae) is a rare endemic tree of Styracaceae in China. In this work, we set forth the complete chloroplast (cp) genome sequence of M. wangianum using next-generation sequencing. The entire cp genome was determined to be 157,196 bp in length. It contained large single-copy (LSC) and small single-copy (SSC) regions of 90,210 bp and 18,4561 bp, respectively, which were separated by a pair of 24,265 bp inverted repeat (IR) regions. The genome contained 128 genes, including 83 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The overall GC content of the genome is 37.19%. Phylogenetic analysis confirmed the traditional family-level Taxonomy of Melliodendron, indicating that M. wangianum is closely related to a sister species to M. xylocarpum in Styracaceae.

An approach to genetic resources conservation of peripheral isolated plant populations: the case of an island narrow endemic species

This study reinforces the argument that forest genetic resources for peripheral isolated plant populations (PIPP) need to come under rationalistic assessment, for developing and proposing conservation strategies of forest genetic resources. Cedrus brevifolia is a narrow endemic island tree occurring in a sole population. Using biparentally and paternally inherited microsatellites, the genetic contribution and genetic variation patterns within sites (subpopulations) and within plantations of this species were assessed. The C. brevifolia population recorded uneven partition of genetic diversity at the site and at local scales; mirroring the demography and genetic evolutionary factors that occurred in long-term at the intra-species level. Results from the plantations imply that screening and rejection of unsuitable seedlings before plantation establishment did not influence the genetic divergence of planted trees from the general genetic pool of natural population. Based on these outcomes, numerous conservation measures are proposed, towards maintaining the species’ genetic resources. These measures need to ensure the dynamic processes within stands. Thus, this study argues that for PIPP which recorded high genetic diversity and non-uniform distribution of genetic viability (complex genetic patterns), the several small conservation units seem to be the most rationalistic conservation units. In such case, forest genetic micro-reserves (GMR) can be enacted, where on-the-point dynamic in situ conservation activities can be adopted, while the GMR could be used for ex situ conservation purposes. In conclusion, in PIPP the maintenance of genetic diversity should be regarded as one of the main prerequisites for sustainable management and long-term survival of the species.

De novo genome assembly of the endangered Acer yangbiense, a plant species with extremely small populations endemic to Yunnan Province, China.

Background Acer yangbiense is a newly described critically endangered endemic maple tree confined to Yangbi County in Yunnan Province in Southwest China. It was included in a programme for rescuing the most threatened species in China, focusing on “plant species with extremely small populations (PSESP)”.FindingsWe generated 64, 94, and 110 Gb of raw DNA sequences and obtained a chromosome-level genome assembly of A. yangbiense through a combination of Pacific Biosciences Single-molecule Real-time, Illumina HiSeq X, and Hi-C mapping, respectively. The final genome assembly is ∼666 Mb, with 13 chromosomes covering ∼97% of the genome and scaffold N50 sizes of 45 Mb. Further, BUSCO analysis recovered 95.5% complete BUSCO genes. The total number of repetitive elements account for 68.0% of the A. yangbiense genome. Genome annotation generated 28,320 protein-coding genes, assisted by a combination of prediction and transcriptome sequencing. In addition, a nearly 1:1 orthology ratio of dot plots of longer syntenic blocks revealed a similar evolutionary history between A. yangbiense and grape, indicating that the genome has not undergone a whole-genome duplication event after the core eudicot common hexaploidization.ConclusionHere, we report a high-quality de novo genome assembly of A. yangbiense, the first genome for the genus Acer and the family Aceraceae. This will provide fundamental conservation genomics resources, as well as representing a new high-quality reference genome for the economically important Acer lineage and the wider order of Sapindales.

Sustainable Land Use Management Needed to Conserve the Dragon’s Blood Tree of Socotra Island, a Vulnerable Endemic Umbrella Species

Unsustainable overgrazing is one of the most important threats to the endemic and endangered population of dragon’s blood tree (Dracaena cinnabari) on Socotra Island (Republic of Yemen). However, there is a lack of information about the exact population size and its conservation status. We estimated the population size of D. cinnabari using remote sensing data. The age structure was inferred using a relationship between crown projection area and the number of branch sections. The conservation importance of each sub-population was assessed using a specially developed index. Finally, the future population development (extinction time) was predicted using population matrices. The total population size estimated consists of 80,134 individuals with sub-populations varying from 14 to 32,196 individuals, with an extinction time ranging from 31 to 564 years. Community forestry controlled by a local certification system is suggested as a sustainable land management approach providing traditional and new benefits and enabling the reforestation of endemic tree species on Socotra Island.

An Enigmatic Small Neosuchian Crocodyliform from the Woodbine Formation of Texas.

New discoveries at the Arlington Archosaur Site (AAS), a Cenomanian (Late Cretaceous) locality in north-central Texas, are filling gaps in our knowledge of mid-Cretaceous Appalachian ecosystems, which remain poorly characterized. The AAS is notable because it preserves a diverse crocodyliform record. As seen in other sites that preserve four or more crocodyliform taxa, the species present at the AAS exhibit different snout shapes and body sizes, indicating that this high diversity of sympatric species was likely sustainable due to niche partitioning. Here we describe Scolomastax sahlsteini gen. et sp. nov., a new species of crocodyliform from the AAS, currently known from a partial right mandibular ramus. This species differs from other crocodyliforms in possessing features associated with durophagy or omnivory, including a shortened mandible, reduced tooth count, heterodonty, a dorsally expanded surangular, and enlarged attachments for jaw adductor muscles. Our phylogenetic analysis places this new taxon within Eusuchia as a member of Paralligatoridae and sister taxon to Paralligator gradilifrons. Scolomastax sahlsteini extends the record of paralligatorids into the Late Cretaceous of North America. This discovery represents the first appearance of this clade on the poorly known landmass of Appalachia, supporting a biogeographic connection between North America and Asia in the Early Cretaceous prior to completion of the Western Interior Seaway. However, relationships among other endemic crocodyliforms and tree instability within Paralligatoridae suggest further analysis is needed to resolve phylogenetic and biogeographic relationships (http://zoobank.org/urn:lsid:zoobank.org:pub:DC114471-6687-4BB5-8FAE-96F7278B1DAF). Anat Rec, 303:801-812, 2020. © 2019 Wiley Periodicals, Inc.

Boldo, Its Secondary Metabolites and their Derivatives

Boldo leaves (Boldo folium, from Peumus boldus Mol.) are very frequently used as a medicinal herb in Chile and are exported to many countries to be used in teas or as extracts included in herbal remedies, primarily as an aid to digestion and as a mild sedative. Scientific support for these uses is scanty, and boldine, an alkaloid viewed as characteristic of the tree and present in high concentration in the bark, is extracted by specialized companies and sold as the supposed main active constituent. Consequently, boldine has been the subject of a considerable number of research papers, while some of the other alkaloids present to a greater extent in the leaves have been relatively neglected except when found in large amounts in other species. These studies range from assays of antioxidant activity to anti-inflammatory, antineoplastic and other medical applications. The essential oil, usually containing a large percentage of the toxic ascaridole, was once used as a vermifuge and is now regarded with caution, but is still of interest as a possible natural insecticide, fungicide, antiparasitic and herbicide. The last decade has seen an explosive increase in papers pointing to possible uses of boldo and its constituents. This review attempts to bring these publications together in a comprehensive way with the purpose of stimulating and orienting further research into the useful properties of this Chilean endemic tree.

Effects of climate changes on distribution of Eremanthus erythropappus and E. incanus (Asteraceae) in Brazil

Phylogeographic patterns of endemic species are critical keys to understand its adaptation to future climate change. Herein, based on chloroplast DNA, we analyzed the genetic diversity of two endemic and endangered tree species from the Brazilian savanna and Atlantic forest (Eremanthus erythropappus and Eremanthus incanus). We also applied the climate-based ecological niche modeling (ENM) to evaluate the impact of the Quaternary climate (last glacial maximum ~ 21 kyr BP (thousand years before present) and Mid-Holocene ~ 6 kyr BP) on the current haplotype distribution. Moreover, we modeled the potential effect of future climate change on the species distribution in 2070 for the most optimistic and pessimistic scenarios. One primer/enzyme combination (SFM/HinfI) revealed polymorphism with very low haplotype diversity, showing only three different haplotypes. The haplotype 1 has very low frequency and it was classified as the oldest, diverging from six mutations from the haplotypes 2 and 3. The E. erythropappus populations are structured and differ genetically according to the areas of occurrence. In general, the populations located in the north region are genetically different from those located in the center-south. No genetic structuring was observed for E. incanus. The ENM revealed a large distribution during the past and a severe decrease in geographic distribution of E. erythropappus and E. incanus from the LGM until present and predicts a drastic decline in suitable areas in the future. This reduction may homogenize the genetic diversity and compromise a relevant role of these species on infiltration of groundwater.

Effect of pre-germinative treatments on <i>Nothofagus glauca</i> seed germination and seedling growth

Background: Nothofagus glauca (Phil.) Krasser (Nothofagaceae, “Hualo”) is an endemic tree of the Mediterranean zone of Chile. The natural forests in this area have been severely fragmented as a result of human causes such as replacement by agricultural crops and fast-growing tree species. From 1975, these forests have declined from 900,000 ha to 145,000 ha, so it is categorised on the IUCN Red List as ‘vulnerable’. In restoring this ecosystem, efforts should focus, in part, on the propagation of quality stock. However, information on propagation systems is still insufficient.
 Methods: We aimed to analyse the effect of different pre-germinative treatments and sowing times on seed germination, and seedling growth and quality. The pre-germinative treatments were: (i) cold stratification; (ii) soaking in gibberellic acid (GA3) and thiourea solution; and (iii) nursery cultivation, while the sowing times were July, August and September.
 Results: A high germination capacity was achieved by: soaking the seeds in GA3 solution irrespective of concentration; stratifying, irrespective of period; or soaking in 7.5 mg L-1 thiourea solution, values significantly varied from that of the control treatments. The sowing time was not relevant in terms of the percentage of germination or seedling development. Stratification at 5°C for 60 days produced the best quality indices for N. glauca seedlings but no significant differences were found in any of the morphological attributes tested as a result of the pre-germinative treatments.
 Conclusions: The pre-germinative treatments significantly improved the germination and seedlings growth of N. glauca. Cold stratification at 5°C for 60 days is recommended as it produced suitable seedlings for field establishment. Gibberellic acid and thiourea did not produce important effects on seedling growth. Our results suggest the presence of endogenous physiological dormancy of the N. glauca seeds. The results of this study provide important information on propagation and nursery techniques of N. glauca, which can be used in restoration programmes.

A spatial stream-network approach assists in managing the remnant genetic diversity of riparian forests

Quantifying the genetic diversity of riparian trees is essential to understand their chances to survive hydroclimatic alterations and to maintain their role as foundation species modulating fluvial ecosystem processes. However, the application of suitable models that account for the specific dendritic structure of hydrographic networks is still incipient in the literature. We investigate the roles of ecological and spatial factors in driving the genetic diversity of Salix salviifolia, an Iberian endemic riparian tree, across the species latitudinal range. We applied spatial stream-network models that aptly integrate dendritic features (topology, directionality) to quantify the impacts of multiple scale factors in determining genetic diversity. Based on the drift hypothesis, we expect that genetic diversity accumulates downstream in riparian ecosystems, but life history traits (e.g. dispersal patterns) and abiotic or anthropogenic factors (e.g. drought events or hydrological alteration) might alter expected patterns. Hydrological factors explained the downstream accumulation of genetic diversity at the intermediate scale that was likely mediated by hydrochory. The models also suggested upstream gene flow within basins that likely occurred through anemophilous and entomophilous pollen and seed dispersal. Higher thermicity and summer drought were related to higher population inbreeding and individual homozygosity, respectively, suggesting that increased aridity might disrupt the connectivity and mating patterns among and within riparian populations.

Impact of habitat loss and fragmentation on reproduction, dispersal and species persistence for an endangered Chilean tree

Survival of rare and endangered plant species following habitat loss and fragmentation is dependent upon in situ reproduction and population persistence, and establishment in new sites, so that stochastic, local extirpation does not lead to species extinction. Here we investigate if and how vegetative and sexual reproduction, propagule dispersal, and seedling establishment promote in situ persistence and establishment in new sites for the endangered, endemic Chilean tree Gomortega keule, in a landscape experiencing extensive habitat loss and fragmentation. Genetic analyses show G. keule reproduces vegetatively, producing large clone groups and providing a mechanism for long-term in situ persistence. Abundant seed set was observed, but seedling establishment was rare. At the single site where seedlings were observed, parentage analysis revealed seed dispersal over greater distances, and in a more aggregated pattern, than would be expected from gravity dispersal alone. We hypothesize that G. keule may represent a ‘seed dispersal anachronism’, wherein the native seed disperser has been lost and possibly replaced by domesticated cattle. The lack of seedling establishment at most sites raises concerns about the ability of existing populations to expand within existing habitat patches or establish at new locations. Globally, habitat loss and fragmentation, coupled with other environmental changes, pose a particular threat to rare species with small populations, because inbreeding and the loss of mutualists can lead to establishment failure and local extirpation. We propose that analysis of a plant’s reproductive strategies as a whole, in its landscape context, is essential for effective species conservation.

Range extension of Actinodaphne bourneae Gamble (Lauraceae): An overlooked endemic tree of Western Ghats, India

Range extension of Actinodaphne bourneae Gamble (Lauraceae): An overlooked endemic tree of Western Ghats, India

Elevated O3 alters soil bacterial and fungal communities and the dynamics of carbon and nitrogen

Although many studies have reported the negative effects of elevated O3 on plant physiological characteristics, the influence of elevated O3 on below-ground processes and soil microbial functioning is less studied. In this study, we examined the effects of elevated O3 on soil properties, soil microbial biomass, as well as microbial community composition using high-throughput sequencing. Throughout one growing season, one-year old seedlings of two important endemic trees in subtropical China: Taxus chinensis (Pilger) Rehd. var. chinensis, and Machilus ichangensis Rehd. Et Wils, were exposed to charcoal-filtered air (CF as control), 100 nl l−1 (E100) or 150 nl l−1 (E150) O3-enriched air, in open top chambers (OTCs). We found that only higher O3 exposure (E150) significantly decreased soil microbial biomass carbon and nitrogen in M. ichangensis, and the contents of organic matter were significantly decreased by E150 in both tree species. Although both levels of O3 exposure decreased NO3-N in T. chinensis, only E150 increased NO3-N in M. ichangensis, and there were no effects of O3 on NH4-N. Moreover, elevated O3 elicited changes in soil microbial community structure and decreased fungal diversity in both M. ichangensis and T. chinensis. However, even though O3 exposure reduced bacterial diversity in M. ichangensis, no effect of O3 exposure on bacterial diversity was detected in soil grown with T. chinensis. Our results showed that elevated O3 altered the abundance of bacteria and fungi in general, and in particular reduced nitrifiers and increased the relative abundance of some fungal taxa capable of denitrification, which may stimulate N2O emissions. Overall, our findings indicate that elevated O3 not only impacts the soil microbial community structure, but may also exert an influence on the functioning of microbial communities.

Promise and Pitfalls of Endemic Resistance for Cultural Resources Threatened by Phytophthora ramorum.

Invasive forest pathogens can harm cultural, economic, and ecological resources. Here, we demonstrate the potential of endemic tree pathogen resistance in forest disease management using Phytophthora ramorum, cause of sudden oak death, in the context of management of tanoak (Notholithocarpus densiflorus), an ecologically unique and highly valued tree within Native American communities of northern California and southern Oregon in the United States. We surveyed resistance to P. ramorum on the Hoopa Valley Indian Reservation and Yurok Indian Reservation in a set of study sites with variable management intensities. Variation in resistance was found at all sites with similar mean and variation across stands, and resistance tended to have a random spatial distribution within stands but was not associated with previous stand management (thinning or prescribed fire) or structural characteristics such as tree density, basal area, or pairwise relatedness among study trees. These results did not suggest host, genetic, management, or environment interactions that could be easily leveraged into treatments to increase the prevalence of resistant trees. We applied epidemiological models to assess the potential application of endemic resistance in this system and to examine our assumption that in planta differences in lesion size-our measure of resistance-reflect linkages between mortality and transmission (resistance) versus reduced mortality with no change in transmission (tolerance). This assumption strongly influenced infection dynamics but changes in host populations-our conservation focus-was dependent on community-level variation in transmission. For P. ramorum, slowing mortality rates (whether by resistance or tolerance) conserves host resources when a second source of inoculum is present; these results are likely generalizable to pathogens with a broader host range. However, when the focal host is the sole source of inoculum, increasing tolerant individuals led to the greatest stand-level pathogen accumulation in our model. When seeking to use variation in mortality rates to affect conservation strategies, it is important to understand how these traits are linked with transmission because tolerance will be more useful for management in mixed-host stands that are already invaded, compared with single-host stands with low or no pathogen presence, where resistance will have the greatest conservation benefits.

Exploring Vegetative Propagation Techniques for the Threatened Pteroceltis tatarinowii Maxim Using Stem Cuttings

Pteroceltis tatarinowii Maxim, the only species of the genus Pteroceltis (family Ulmaceae), is an endemic rare tree species in China. This study was performed to explore vegetative propagation techniques for P. tatarinowii using stem cuttings. First, the effects of exogenous indole-3-butyric acid (IBA) and cutting positions on rooting performance were investigated to screen the appropriate exogenous auxin treatment and to determine the proper cuttings type. The results showed that the control cuttings pretreated with no exogenous IBA, irrespective of whether the stem cuttings were terminal, middle, or basal, rooted in a manner significantly inferior to that of cuttings pretreated with IBA. Their rooting percentage was less than 50%. Among the IBA-treated cuttings, the middle cuttings pretreated with 1000 mg·L−1 IBA rooted best, with the shortest number of days until rooting emergence (20 days), the highest rooting percentage (84.0%), the lowest mortality rate (4.0%), the greatest root number (average of 6.7 per cutting), and the longest roots per cutting (44.4 cm per cutting). Terminal cuttings pretreated with 1000 mg·L−1 IBA acquired satisfactory rooting traits and had the same shortest rooting duration (20 days) and the following parameters: rooting, 70.7%; mortality, 10.7%; average roots per cutting, 5.2; and longest root, 29.1 cm. To further determine the optimum cutting propagation time for this plant, a second experiment was performed and the cuttings were collected beginning in early June, when the growth of the current season was feasible for harvesting cuttings. Stem cuttings collected in late June and middle July had significantly higher rooting percentages (≥80%) compared with those collected in early June (66.7%). The other three rooting parameters were not significantly affected by the collection date. However, according to the overall rooting traits, the cuttings collected in both late June and middle July remarkably outperformed those collected in early June regarding the number of roots and the total root length per cutting. The initial nutrient reserves in the cuttings were also determined. A significant difference in the soluble carbohydrate level was found among collection times, but the nitrogen level in the cuttings was similar. The study revealed that stem cutting propagation of P. tatarinowii was achievable, and it was best achieved with cuttings collected from the terminal and middle positions of the branches of the current season from late June to middle July and treated with 1000 mg·L−1 IBA using the quick dip method.

An assessment of population structure and regeneration status of Magnolia punduana Hk. f. & Th. (Magnoliaceae) in fragmented forests of northeast India

The population structure and regeneration status of Magnolia punduana Hk. f. & Th., an endemic tree species of northeast India were investigated in fragmented forests in the Jarain Hills and in adjoining areas of Meghalaya state. The population structure was discontinuous in all the fragments with the absence of individuals in higher diameter classes. The number of individuals increased with the size of the fragment patches (p 105 ha). The number of seedlings and saplings were also higher in the larger fragments. Human-related disturbances had a negative impact on the species population (p < 0.002). Variation in the population density in different forest patches has been attributed to fragment size, site characteristics and ongoing human disturbances. The restricted distribution of the species coupled with exploitation and habitat destruction underlines the need for its conservation.