Endemic Tree Research Articles

Qualitative phytochemical screening, antibacterial, antioxidant and cytotoxicity activities of the leaf extracts of Diospyros philippinensis A.DC. (Ebenaceae)

The use of medicinal plants for disease prevention and treatment is gaining recognition due to the various biologically active phytochemicals they produce. This study was conducted to assess the ability of the leaf extracts of Diospyros philippinensis A.DC., an endemic tree species in the Philippines for the presence of phytochemical constituents and was examined for potential bioactivities by employing several assays like Kirby-Bauer disc diffusion method, DPPH Assay and MTT assay for antibacterial, antioxidant and cytotoxicity activities of the extracts respectively. Phytochemical test results revealed the presence of alkaloids, flavonoids, saponins, phenols, quinones, cardiac glycosides, phlobatannins, carbohydrate, cardenolides and proteins. The leaf extracts were found to exhibit antibacterial activity against gram-positive bacteria and high antioxidant activity (99.22% ± 0.005) but no cytotoxicity effect was found against the selected cancer cell line. The study therefore concludes that D. philippinensis leaf extract can be a source of antibacterial and chemo preventive agents. This claim may be used as a basis for future investigation.

Effects of culture medium type and plant growth regulators on in vitro culture of Sorbus persica Hedl.

Sorbus persica Hedl. is an Iranian endemic slow-growing tree (fam. rosaceae) and is endangered. It is important in terms of the gene storage, environmental protection, and medicinal uses. To in vitro propagate this species by the lateral bud culture, a factorial experiment was conducted in a completely randomized design in three levels of culture medium and three levels of cytokinin with three replications. For shooting, the DKW, WPM, and MS culture media containing the cytokinins BAP, Kin, and 2ip, and for rooting, the complete and modified DKW, WPM, and MS culture media containing the auxins NAA and IBA separately and in a consecutive application were investigated. The results showed that the best sterilization treatment was a consecutive application of sodium hypochlorite 20% (v/v, 15 min) and mercuric chloride 0.1% (3 min) in summer. The best proliferation and longitudinal growth of shoots was observed in the MS medium containing IBA (0.01 mg l-1), Kin (0.25 mg l-1), and BAP (3 mg l-1) growth regulators. Also, the best rooting was obtained in the DKW medium with a quarter of the concentration of macroelements containing the NAA+IBA hormones (0.3+0.3 mg l-1).

The spatial distribution of the woodland communities and their associated environmental drivers in the Golden Gate Highlands National Park, South Africa

The extreme variability in the topography, altitude and climatic conditions in the temperate Grassland Mountains of Southern Africa is associated with the complex mosaic of grassland communities with pockets of woodland patches. Understanding the relationships between plant communities and environmental parameters is essential in biodiversity conservation, especially for current and future climate change predictions. This article focused on the spatial distribution of woodland communities and their associated environmental drivers in the Golden Gate Highlands (GGHNP) National Park in South Africa. A generalized linear model (GLM) assuming a binomial distribution, was used to determine the optimal environmental variables influencing the spatial distribution of the woodland communities. The Coefficient of Variation (CV) was relatively higher for the topographic ruggedness index (68.78%), topographic roughness index (68.03), aspect (60.04%), coarse fragments (37.46%) and the topographic wetness index (31.33) whereas soil pH, bulk density, sandy and clay contents had relatively less variation (2.39%, 3.23%, 7.56% and 8.46% respectively). In determining the optimal number of environmental variables influencing the spatial distribution of woodland communities, roughness index, topographic wetness index, soil coarse fragments, soil organic carbon, soil cation exchange capacity and remote-sensing based vegetation condition index were significant (p 0.05) and positively correlated with the woodland communities. Soil nitrogen, clay content, soil pH, fire and elevation were also significant but negatively correlated with the woodland communities. The area under the curve (AUC) of the receiver operating characteristics (ROC) was 0.81. This was indicative of a Parsimonious Model with explanatory predictive power for determination of optimal environmental variables in vegetation ecology.Conservation implications: The isolated woodland communities are sources of floristic diversity and important biogeographical links between larger forest areas in the wider Drakensberg region. They provide suitable habitats for a larger number of forest species and harbour some of the endemic tree species of South Africa. They also provide watershed protection and other important ecosystem services. Understanding the drivers influencing the spatial distribution and persistence of these woodland communities is therefore key to conservation planning in the area.

Description of an Australian endemic species of Trioza (Hemiptera: Triozidae) pest of the endemic tea tree, Melaleuca alternifolia (Myrtaceae).

Psyllids, also known as jumping plant lice, are phloem feeding Hemiptera that often show a strict species-specific relationship with their host plants. When psyllid-plant associations involve economically important crops, this may lead to the recognition of a psyllid species as an agricultural or horticultural pest. The Australian endemic tea tree, Melaleuca alternifolia (Maiden & Betche) Cheel., has been used for more than a century to extract essential oils and, long before that, as a traditional medicine by Indigenous Australian people. Recently, a triozid species has been found to damage the new growth of tea trees both in Queensland and New South Wales, raising interest around this previously undocumented pest. Furthermore, adults of the same species were also collected from Citrus plantations, leading to potential false-positive records of the exotic pest Trioza erytreae (Del Guercio 1918), the African Citrus psyllid. Here we describe for the first time Trioza melaleucae Martoni sp. nov. providing information on its distribution, host plant associations and phylogenetic relationships to other Trioza species. This work enables both morphological and molecular identification of this new species, allowing it to be recognized and distinguished for the first time from exotic pests as well as other Australian native psyllids. Furthermore, the haplotype network analysis presented here suggests a close relationship between Trioza melaleucae and the other Myrtaceae-feeding Trioza spp. from Australia, New Zealand, and Taiwan.

Heat Stress Affects the Physiological and Biochemical Quality of Dalbergia nigra Seeds in vitro

Abstract The jacaranda of Bahia (Dalbergia nigra (Vell.) Allemão ex Benth) is an endemic tree of a Brazilian neotropical biodiversity hotspot and is of great ecological and economic interest. Given the threat of extinction due to timber overexploitation and climate change, the present study aimed to analyze the physiological and biochemical quality of D. nigra seeds exposed to heat stress. The seeds were sown in a test tube containing woody plant culture medium, kept in a biochemical oxygen demand chamber at 45°C for 0, 24, 48, 72, and 96 hours, and then maintained in the same chamber at 25°C for 30 days. Physiological analyses of moisture, electrical conductivity, germination speed index, normal and abnormal seedlings, seedling length, root length, hypocotyl length, collar diameter, seedling and root dry mass, and Dickson quality index revealed a drop in germination and vigor with prolonged heat stress, dropping from 95% to 0% between 0 and 96 hours. This was accompanied by a reduction in the content of carbohydrates, lipids, and proteins. Therefore, the vigor and quality of seedlings is negatively influenced by exposure to heat stress at 45°C.

The conservation and ecology of the British Virgin Islands endemic tree, Vachellia anegadensis

AbstractNumerous island species have gone extinct and many extant, but threatened, island endemics require ongoing monitoring of their conservation status. The small tree Vachellia anegadensis was formerly thought to occur only on the limestone island of Anegada in the British Virgin Islands and was categorized as Critically Endangered. However, in 2008 it was discovered on the volcanic island of Fallen Jerusalem, c. 35 km from Anegada, and in 2018 it was recategorized as Endangered. To inform conservation interventions, we examined the species’ distribution, genetic population structure, dependency on pollinators and preferred habitat, and documented any threats. We found V. anegadensis to be locally widespread on Anegada but uncommon on Fallen Jerusalem and established that geographical location does not predict genetic differentiation amongst populations. Vachellia anegadensis produces the highest number of seed pods when visited by animal pollinators, in particular Lepidoptera. Introduced animals and disturbance by humans appear to be the main threats to V. anegadensis, and in situ conservation is critical for the species’ long-term survival.

Distribution of Panama\u2019s narrow-range trees: are there hot-spots?

BackgroundTree species with narrow ranges are a conservation concern because heightened extinction risk accompanies their small populations. Assessing risks for these species is challenging, however, especially in tropical flora where their sparse populations seldom appear in traditional plots and inventories. Here, we utilize instead large scale databases that combine tree records from many sources to test whether the narrow-range tree species of Panama are concentrated at certain elevations or in certain provinces. Past investigations have suggested that the Choco region of eastern Panama and the high mountains of western Panama may be potential hotspots of narrow-range tree species.MethodsAll individual records were collected from public databases, and the range size of each tree species found in Panama was estimated as a polygon enclosing all its locations. Species with ranges <20,000 km2 were defined as narrow endemics. We divided Panama into geographic regions and elevation zones and counted the number of individual records and the species richness in each, separating narrow-range species from all other species.ResultsThe proportion of narrow endemics peaked at elevations above 2000 m, reaching 17.2% of the species recorded. At elevation <1500 m across the country, the proportion was 6-11%, except in the dry Pacific region, where it was 1.5%. Wet forests of the Caribbean coast had 8.4% narrow-range species, slightly higher than other regions. The total number of narrow endemics, however, peaked at mid-elevation, not high elevation, because total species richness was highest at mid-elevation.ConclusionsHigh elevation forests of west Panama had higher proportions of narrow endemic trees than low-elevation regions, supporting their hot-spot status, while dry lowland forests had the lowest proportion. This supports the notion that montane forests of Central America should be a conservation focus. However, given generally higher diversity at low- to mid-elevation, lowlands are also important habitats for narrow-range tree species, though conservation efforts here may not protect narrow-range tree species as efficiently.

Biochemical characterization of Peumus boldus fruits: Insights of its antioxidant properties through a theoretical approach

Peumus boldus is an endemic tree species from Chile whose leaves have been the focus of study for decades given that their infusions are reported to relieve rheumatic symptoms, headache, dyspepsia, urinary tract inflammation, and symptoms of other illnesses. These health properties have been studied mainly using leaves and bark, then it is relevant to know more about these properties in different parts of the plant. Considering the importance of P. boldus fruits in the diet of some rural populations, we analyzed their properties to explore its impact on the Chilean population health. Liquid chromatography and mass spectrometry analysis confirmed the presence of alkaloids such as boldine, although aporphine N-methyl-laurotetanine was the most abundant. In addition, flavonoids catechin, chrysin and quercetin were also found in the extract. Cytotoxicity and anti-inflammatory activities of the fruit extract were invitro tested by using a murine macrophage cell model, observing that a diluted fraction of the extract was not cytotoxic, but showed anti-inflammatory activity, which is likely attributed to antioxidants activities. By means of quantum chemical calculations, we calculated the redox potential of the respective alkaloids and flavonoids found in the extract. Results suggest a synergistic effect between alkaloids and flavonoids, where boldine and N-methyl-laurotetanine showed similar antioxidant properties. Finally, we present a description of the oxidation mechanisms for both groups of molecules which will sustain P. boldus fruit biological properties, in order to give this kind of fruits scientific value focusing on human health.

Characterisation and Distribution of Karaka Ōkahu Purepure Virus-A Novel Emaravirus Likely to Be Endemic to New Zealand.

We report the first emaravirus on an endemic plant of Aotearoa New Zealand that is, to the best of our knowledge, the country’s first endemic virus characterised associated with an indigenous plant. The new-to-science virus was identified in the endemic karaka tree (Corynocarpus laevigatus), and is associated with chlorotic leaf spots, and possible feeding sites of the monophagous endemic karaka gall mite. Of the five negative-sense RNA genomic segments that were fully sequenced, four (RNA 1–4) had similarity to other emaraviruses while RNA 5 had no similarity with other viral proteins. A detection assay developed to amplify any of the five RNAs in a single assay was used to determine the distribution of the virus. The virus is widespread in the Auckland area, particularly in mature trees at Ōkahu Bay, with only occasional reports elsewhere in the North Island. Phylogenetic analysis revealed that its closest relatives are pear chlorotic leaf spot-associated virus and chrysanthemum mosaic-associated virus, which form a unique clade within the genus Emaravirus. Based on the genome structure, we propose this virus to be part of the family Emaravirus, but with less than 50% amino acid similarity to the closest relatives in the most conserved RNA 1, it clearly is a novel species. In consultation with mana whenua (indigenous Māori authority over a territory and its associated treasures), we propose the name Karaka Ōkahu purepure virus in te reo Māori (the Māori language) to reflect the tree from which it was isolated (karaka), a place where the virus is prevalent (Ōkahu), and the spotted symptom (purepure, pronounced pooray pooray) that this endemic virus appears to cause.

Spatial distribution of argan tree influence on soil properties in southern Morocco

Abstract. The endemic argan tree (Argania spinosa) populations in southern Morocco are highly degraded due to overbrowsing, illegal firewood extraction and the expansion of intensive agriculture. Bare areas between the isolated trees increase due to limited regrowth; however, it is unknown if the trees influence the soil of the intertree areas. Hypothetically, spatial differences in soil parameters of the intertree area should result from the translocation of litter or soil particles (by runoff and erosion or wind drift) from canopy-covered areas to the intertree areas. In total, 385 soil samples were taken around the tree from the trunk along the tree drip line (within and outside the tree area) and the intertree area between two trees in four directions (upslope, downslope and in both directions parallel to the slope) up to 50 m distance from the tree. They were analysed for gravimetric soil water content, pH, electrical conductivity, percolation stability, total nitrogen content (TN), content of soil organic carbon (SOC) and C/N ratio. A total of 74 tension disc infiltrometer experiments were performed near the tree drip line, within and outside the tree area, to measure the unsaturated hydraulic conductivity. We found that the tree influence on its surrounding intertree area is limited, with, e.g., SOC and TN content decreasing significantly from tree trunk (4.4 % SOC and 0.3 % TN) to tree drip line (2.0 % SOC and 0.2 % TN). However, intertree areas near the tree drip line (1.3 % SOC and 0.2 % TN) differed significantly from intertree areas between two trees (1.0 % SOC and 0.1 % TN) yet only with a small effect. Trends for spatial patterns could be found in eastern and downslope directions due to wind drift and slope wash. Soil water content was highest in the north due to shade from the midday sun; the influence extended to the intertree areas. The unsaturated hydraulic conductivity also showed significant differences between areas within and outside the tree area near the tree drip line. This was the case on sites under different land usages (silvopastoral and agricultural), slope gradients or tree densities. Although only limited influence of the tree on its intertree area was found, the spatial pattern around the tree suggests that reforestation measures should be aimed around tree shelters in northern or eastern directions with higher soil water content or TN or SOC content to ensure seedling survival, along with measures to prevent overgrazing.

Seed Storage and Germination Performance in Knema attenuata - an Endemic Medicinal Tree of Western Ghats, India

Detailed study on seed storage and germination trailed in Knema attenuata (Wall. ex Hook. f. &amp; Thomson) Warb.– the IUCN Red Listed ‘least concern’ medicinal tree species revealed that seeds were of recalcitrant nature. Viability of the seeds could be maintained for a longer period of up to 6 months with 47% Moisture content (mc) when kept in closed polycarbonate bottles at seed bank condition [20±20C Temp. and 40% Relative Humidity (RH)]. The 55% seed germination under normal climatic condition could be enhanced to a much higher percentage (75±5) inside the mist house chamber (34±30C Temp. and 70-80% RH).

Cytotoxicity of Poupartone B, an Alkyl Cyclohexenone Derivative from Poupartia borbonica, against Human Cancer Cell Lines.

Poupartia borbonica is an endemic tree from the Mascarene Islands that belongs to the Anacardiaceae family. The leaves of this plant were phytochemically studied previously, and isolated alkyl cyclohexenone derivatives, poupartones A - C, demonstrated antiplasmodial and antimalarial activities. In addition to their high potency against the Plasmodium sp., high toxicity on human cells was also displayed. The present study aims to investigate in more detail the cytotoxicity and pharmacological interest of poupartone B, one of the most abundant derivatives in the leaves of P. borbonica. For that purpose, real-time live-cell imaging of different human cancer cell lines and normal fibroblasts, treated or not treated with poupartone B, was performed. A potent inhibition of cell proliferation associated with the induction of cell death was observed. A detailed morphological analysis of different adherent cell lines exposed to high concentrations of poupartone B (1 - 2 µg/mL) demonstrated that this compound induced an array of cellular alterations, including a rapid retraction of cellular protrusions associated with cell rounding, massive cytoplasmic vacuolization, loss of plasma membrane integrity, and plasma membrane bubbling, ultimately leading to paraptosis-like cell death. The structure-activity relation of this class of compounds, their selective toxicity, and pharmacological potential are discussed.

Tree hazards compounded by successive climate extremes after masting in a small endemic tree, Distylium lepidotum, on subtropical islands in Japan.

Ongoing global warming increases the frequency and severity of tropical typhoons and prolonged drought, leading to forest degradation. Simultaneous and/or successive masting events and climatic extremes may thus occur frequently in the near future. If these climatic extremes occur immediately after mass seed reproduction, their effects on individual trees are expected to be very severe because mass reproduction decreases carbohydrate reserves. While the effects of either a single climate extreme or masting alone on tree resilience/growth have received past research attention, understanding the cumulative effects of such multiple events remains challenging and is crucial for predicting future forest changes. Here, we report tree hazards compound by two successive climate extremes, a tropical typhoon and prolonged drought, after mass reproduction in an endemic tree species (Distylium lepidotum Nakai) on oceanic islands. Across individual trees, the starch stored within the sapwood of branchlets significantly decreased with reproductive efforts (fruit mass/shoot mass ratio). Typhoon damage significantly decreased not only the total leaf area of apical shoots but also the maximum photosynthetic rates. During the 5‐month period after the typhoon, the mortality of large branchlets (8–10‐mm diameter) increased with decreasing stored starch when the typhoon hit. During the prolonged summer drought in the next year, the recovery of total leaf area, stored starch, and hydraulic conductivity was negatively correlated with the stored starch at the typhoon. These data indicate that the level of stored starch within branchlets is the driving factor determining tree regrowth or dieback, and the restoration of carbohydrates after mass reproduction is synergistically delayed by such climate extremes. Stored carbohydrates are the major cumulative factor affecting individual tree resilience, resulting in their historical effects. Because of highly variable carbohydrate levels among individual trees, the resultant impacts of such successive events on forest dieback will be fundamentally different among trees.

Nectar provision attracts hummingbirds and connects interaction networks across habitats

Many ecosystems have been modified by humans, creating novel habitats that include human‐provided resources. Gardens adjacent to native habitats may affect plant–pollinator interactions by altering the determinants of interactions and species specialization. Here, we characterized a network comprising plants and hummingbirds interacting in a birdwatching garden with human‐provided resources (nectar feeders and exotic plants) and adjacent Andean cloud forest in Colombia. Specifically, we investigated the proportion of hummingbirds visiting feeders and native/exotic plants to evaluate the connection between the habitats and the ecological determinants of the interaction network. Hummingbirds relied heavily on artificial nectar feeders in the garden, leaving the natural cloud forest for resources. Morphological matching was the single most important predictor of the observed pairwise interactions, for both hummingbirds and plants. At the species level, longer flowering phenology and a higher amount of sugar in nectar led to a higher degree for plants (i.e. the number of visiting hummingbird species). In contrast, a longer floral corolla was associated with lower specialization. Abundance was the best predictor of the number of partners for hummingbirds. The garden created for birdwatching attracted most, but not all, hummingbird species beyond their natural cloud forest habitat. Interestingly, the most frequently visited plants in the garden were native, especially the endemic and endangered tree Zygia lehmannii (Fabaceae). Our results show that some ecological mechanisms determining interactions in natural communities still hold in intensively modified habitats. Furthermore, a compromise between conservation and hummingbirds’ attraction to birding lodges/gardens is possible, for instance by favouring native and endemic plant species that are highly attractive for pollinators.

The conservation of endemic and endangered tree species Kalapia celebica Kosterm with Mycorrhizal bio-fertilizer technology in post-gold mining areas

This research aimed to determine the effectiveness of mycorrhizal fungi of arbuscular (AMF) on the growth of Kalappia celebica Kosterm at 4 months aged after planting in gold mining land of PT. Panca LogamMakmur, Bombana, Southeast Sulawesi. This study was designed using block randomized design (BRD) consisted of 5 treatments, i.e. control, Constrictum etunicatum, Septoglomus constrictum, Glomus claroideum Schenk & Smith, Glomus coronatum Giovann, and mixed AMF (G. claroideum, G. coronatum). Each treatment had three replications. The results showed that AMF colonization significantly increased the growth of K. celebica plants. G. coronatum and C. etunicatum significantly increased the height, diameter, and leaf area and leaves dry weight of K. celebica. AMF can be used for the conservation of extinct tree species in gold mining lands.

Conserving Dialium travancoricum, a Critically Endangered endemic tree

Conserving <i>Dialium travancoricum</i>, a Critically Endangered endemic tree

Hotter Drought Escalates Tree Cover Declines in Blue Oak Woodlands of California

California has, in recent years, become a hotspot of interannual climatic variability, recording devastating climate-related disturbances with severe effects on tree resources. Understanding the patterns of tree cover change associated with these events is vital for developing strategies to sustain critical habitats of endemic and threatened vegetation communities. We assessed patterns of tree cover change, especially the effects of the 2012–2016 drought within the distribution range of blue oak (Quercus douglasii), an endemic tree species to California with a narrow geographic extent. We utilized multiple, annual land-cover and land-surface change products from the U.S. Geological Survey (USGS) Land Change Monitoring, Assessment and Projection (LCMAP) project along with climate and wildfire datasets to monitor changes in tree cover state and condition and examine their relationships with interannual climate variability between 1985 and 2016. Here, we refer to a change in tree cover class without a land-cover change to another class as “conditional change.” The unusual drought of 2012–2016, accompanied by anomalously high temperatures and vapor pressure deficit, was associated with exceptional spikes in the amount of both fire and non-fire induced tree cover loss and tree cover conditional change, especially in 2015 and 2016. Approximately 1,266 km2 of tree cover loss and 617 km2 of tree cover conditional change were recorded during that drought. Tree cover loss through medium to high severity fires was especially large in exceptionally dry and hot years. Our study demonstrates the usefulness of the LCMAP products for monitoring the effects of climatic extremes and disturbance events on both thematic and conditional land-cover change over a multi-decadal period. Our results signify that blue oak woodlands may be vulnerable to extreme climate events and changing wildfire regimes. Here, we present early evidence that frequent droughts associated with climate warming may continue to affect tree cover in this region, while drought interaction with wildfires and the resulting feedbacks may have substantial influence as well. Consequently, efforts to conserve the blue oak woodlands, and potentially other vegetation communities in the Western United States, may benefit from consideration of climate risks as well as the potential for climate-fire and vegetation feedbacks.

Assessment of How Natural Stand Structure for Narrow Endemic Cedrus brevifolia Henry Supports Silvicultural Treatments for Its Sustainable Management

Cedrus brevifolia Henry is a narrow endemic tree species of Cyprus flora. The objectives of this study are to develop silvicultural treatments for the conservation of the species formations based on the stand structure analysis of C. brevifolia natural forest and to present the characteristics of the first application of the treatments through silvicultural interventions. Six structural types were distinguished in C. brevifolia formations in the study area located in the state forest of Paphos. For each structural type, six circular plots of approximately 500 m2 were established. In each plot, various measurements and estimations were recorded. Then, silvicultural interventions were applied in the plots of the mixed C. brevifolia formations. In the formations of C. brevifolia a great number of trees grow in the understory. In the very productive and in the poorly productive sites C. brevifolia occurs only in pure formations. The basal area of C. brevifolia in pure formations ranges from 19.04 m2·ha-1 in poorly productive sites to 38.49 m2·ha-1 in fairly productive sites. Cedrus brevifolia is the most competitive species of the study area as a result of both shade tolerance and the wide range of its site sensitivity behavior. The climax of the study area are the pure stands of C. brevifolia having an understory of Quercus alnifolia Poech and a sparse occurrence of Pinus brutia Ten., mainly in moderately productive sites. Forest practice has to, as much as possible, unite species formations in order to create extensive areas of C. brevifolia formations.

The impacts of flowering phenology on the reproductive success of the narrow endemic Nouelia insignis Franch. (Asteraceae).

Nouelia insignis Franch. (Asteraceae) is a short, narrow endemic and endangered tree, growing with a natural population in the dry and hot valley of the Jinsha River in the southwest area of China. In this work, flowering phenology (time and duration), floral biology, visit frequency and behavior of pollinators, and pollination characteristics were studied based on investigation in the field and analysis in the laboratory with the help of a stereomicroscope, and the relationship between seed setting rate and reproductive traits, as well as the relationship between flowering time and rainfall before flowering, was tested using the method of general linear regression model. The results showed that natural population of N. insignis exhibited high flowering synchrony with relatively stable flowering duration, and the flowering time fluctuated greatly depending on the rainfall 5 months before flowering. The pollination of N. insignis required pollinators, and insect activities played a very important role in the pollination process. However, lack of the pollinators was not a limitation for reproductive fitness in N. insignis, although the number of pollinators was small and the frequency of visits was low. In addition, no pollen limitation was found during pollination. The average seed setting rate of N. insignis in the natural condition was only 1.52%–3.73%, and it was generally affected by changes in flowering phenology between years and had a higher seed set in early flowering year. The annual variation of seed set might be related to the annual variations of stamen and pistil functions, such as changes of pollen viability and stigma receptivity, which were closely related to flowering time. The results of this study are of value for further conservation actions on natural population of this threatened endemic plant.

Different Responses of Endemic and Alien Tree Squirrels to Tree Seed Chemicals

Quercus acorns and coniferous cones are the main food sources for tree squirrels, and the chemical contents of seeds, such as tannins and terpenes, are predicted to affect the squirrels' food preference. The tolerance of squirrels to chemical contents may vary between species that have evolved in different environments. The consumption of artificial food containing tannic acids or terpenes were compared between the endemic Sciurus lis and two alien species, S. vulgaris and Callosciurus erythraeus. Sciurus lis ate foods containing up to 4% tannic acid, whereas S. vulgaris and C. erythraeus ate foods containing 8% tannic acid. Sciurus lis and S. vulgaris could eat food containing a high concentration of terpenes (up to 0.3% α-pinene and 2% limonene), whereas the food consumption by C. erythraeus decreased drastically with increasing terpene concentrations. The two alien squirrels are highly resistant to tannins and thus the acorns of most Quercus species may be available for them. Sciurus lis exhibits a lower tolerance to tannins, but can consume foods with high concentrations of terpenes, suggesting a strong adaptation to coniferous forests, but not to Quercus forests. More attention must be paid to conserving suitable habitats for S. lis, an endemic relict species.