Subjects: Biology >> Botany >> Applied botany submitted time 2024-04-17 Cooperative journals: 《广西植物》
Abstract： Mangrove forests, characterized by high photosynthetic rates and low light compensation point, exhibit high Gross Primary Production (GPP), an important component of "blue carbon". Accurate estimation of regional GPP and quantification of its limiting factors are greatly significant for China to achieve its carbon neutrality goals. In this paper, we estimated the GPP of mangrove ecosystems in Hainan Island from 2016 to 2020 based on the Mangrove Vegetation Photosynthesis Light Use Efficiency (MVP-LUE) model using Sentinel-2 imagery and environmental data; and we also explored the spatiotemporal distribution pattern of GPP and its driving mechanism. The results were as follows: (1) During the study period, the annual GPP of mangrove ecosystems on Hainan Island showed an increasing trend, with higher GPP in the eastern than western regions and northern than southern regions. The mangroves distributed over a large area in northeastern Hainan Island dominate the temporal variation patterns at the whole island scale. However, distinct differences exist in the temporal dynamics across different regions of the mangrove ecosystem in Hainan Island. (2) In terms of the formation mechanism, the spatial and temporal distribution pattern of GPP of mangrove ecosystems on Hainan Island was driven by a combination of multiple meteorological factors. Seasonally within each year, during the transition from the dry season to rainy season, GPP was higher due to lower limitation from air temperature (Tair), and the promoting effects of photosynthetically active radiation (PAR) and sea surface temperature; in the middle of the dry season, low Tair imposed a serious limitation on GPP, but this Tair limitation was weakened with decreasing latitude. In the rainy season, higher cloud cover resulted in PAR becoming a limiting factor for GPP. At the end of the paper, we discussed the uncertainties and limitations of MVP-LUE, and the spatiotemporal distribution patterns of mangrove ecosystem GPP not only be constrained by environmental factors, but species composition and forest age structure can also be driving factors. The results of this study provide basic data to assess the contribution of regional mangrove forests to the global carbon cycle, and theoretical support to reveal the key environmental factors affecting mangrove ecosystem carbon dynamics.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-07-13 Cooperative journals: 《广西植物》
Abstract： Ottelia cordata is a kind of rare and endangered submerged plant that grows in freshwater wetlands in northern Hainan Island (from Haikou to Wenchang). This species has a beautiful appearance and is famous for its “flower river” landscape, which makes it have a high ornamental value. With the intensification of human activities, the habitat of O. cordata sharply reduced and fragmented, making it endangered. Here, we studied the pollination biology of O. cordata for further in-situ and ex-situ conservation. The results showed that: (1) The sex ratio of male and female individuals is about 1︰2, and the morphologies of male and female flowers were similar, but the female flowers were slightly larger than the male. (2) Ottelia cordata has high pollen activity and stigma receptivity in budding and blooming phases. (3) The main pollinator, Apis cerana, visits male flowers more frequently than females, with higher pollination efficiency. (4) The distance between the color loci of pistils and stamens was significantly higher than the discrimination threshold of the pollinator. (5) The fruit setting percentage under natural pollination is similar to that under artificial pollination (95.29% and 98.42%, respectively), and there is no apomixis and low pollen limitation in the natural population of O. cordata. In conclusion, the deceptive pollination of O. cordata simulated by both sexes is imperfect. Pollinators can visually distinguish female and male flowers. However, the large number of male flowers of O. cordata attracted many insects to visit flowers, which increases the probability of “mistake” pollination and is enough for the reproductive needs of female flowers. Therefore, future ex-situ conservation and artificial population restoration should pay more attention to population size, sex ratio, and the number of local pollinators.
Subjects: Psychology >> Cognitive Psychology submitted time 2019-04-15
Abstract： " It is reported that, one primary way for school children to acquire vocabularies is by deriving word meanings from contexts. The typical deficit of developmental dyslexia is that they have smaller vocabulary size than their chronological age-matched children. One recent study has examined the cognitive processes underlying dyslexic children’s novel word learning during reading by using eye tracking. This is a method that is well established as a means of investigating reading behaviour by measuring when and where the eye fixates on text as written language is processed naturally. It should be noted that all the studies investigating novel word learning measured fixation durations on novel words fixated by dyslexic children with a view to quantifying the time required for those novel words to be successfully identified within the context of a sentence. In the present study we investigated saccadic targeting in relation to novel word learning in dyslexia children. Each novel word was embedded into eight sentences. Each provided a context for readers to form a new lexical representation. Two groups of dyslexic children and age-matched control children’s eye movements were recorded when they read sentences, each including 22 individuals. Given the ongoing lexical processing difficulty influences the basic decision of “where to target” in Chinese reading, the novel word poses substantial processing difficulty, particular for dyslexic children with inefficient lexical processing, we predict that dyslexic children would be less efficient to target the eyes than control children did in novel word learning. Consistent with our prediction, the mean initial landing positions on novel words were further away from the word center for dyslexic than control children, showing that the basic decision of saccadic targeting on novel words was less efficient for dyslexic than control children. Additionally, we categorized 8 exposures to novel words as being two learning stages: Learning stage 1 including exposures 1 to 4; and learning stage 2 including the exposures from 5 to 8. We aimed to examine whether they were able to modulate their saccadic targeting as the accumulated learning of novel words. The results showed that, control children targeted the initial saccades closer to the word centers with increased exposures, while such effect did not occur for dyslexic children. These findings indicate that control children adjusted the initial saccadic targeting based on lexical familiarity information, while dyslexic children did not. On the basis of the findings above, we argue that, dyslexic children may adopt more careful strategy of saccade-target selection given their lower efficiency in word processing, such that they had lower efficiencies in the basic decision of saccadic targeting, as well as the usage of “lexical familiarity information” to modulate the saccadic targeting to novel words. This might account for their low word acquisition efficiency in reading.
Subjects: Psychology >> Developmental Psychology submitted time 2018-11-19
Abstract： " Previous studies have shown that the amount of vocabularies of children with developmental dyslexia is remarkably lower than that of normal children, thus, it becomes one of the primary indicators for discriminating dyslexia in clinical (Shu et al., 2006). Children develop vocabularies at an extremely high rate in primary school, and a conservative estimate shows that approximately one-third of vocabulary growth is acquired by accidental learning in natural reading (Fukkink, 2005). The critical process of this way to learn words, is to infer the word meaning by gathering useful sources base on lexical and contextual cues. Chinese developmental dyslexia typically have deficits in the aspects of morphological- and phonological-related processing, we infer they would be less skilled to derive the word meaning by using lexical information. The first experiment is designed to examine the dyslexic children’s performance of novel word learning in reading. In Experiment 1, the novel words were embedded into eight sentences, each of which provided a context for readers to form a new lexical representation. Three groups of children were selected as participants, including children with developmental dyslexia (DD), the chronological age-matched children (CA), and reading level-matched children (RL). They were instructed to read sentences containing novel words as their eye movements were recorded. The results showed that, reading times on target words gradually reduced with the increasing of learning stages. Children with developmental dyslexia needed more contexts to begin to decrease for the measures of first fixation duration and gaze duration, and showed a slower decline on total fixation time as compared to age-matched and reading level-matched children. It suggests that more contexts are necessary for dyslexic children to learn novel words in reading. The insertion of spaces between words, has been proven to be an effective way of improving children’s word learning efficiency (Blythe et al., 2012; Liang et al., 2015). In Experiment 2, we examined whether children with dyslexia were more benefit from word spacing in word learning because of their low-level of reading skills. Three groups of children as the same in Experiment 1 were instructed to read sentences in unspaced, and word-spaced formats. The results showed that all children were benefit from word spacing in word learning, and it was more pronounced for children with- than without- dyslexia. We argue that word spacing may allow readers to form a more fully specified representation of the novel word, or to strengthen connections between representations of the constituent characters and the multi-character word. Our findings provide robust evidence that Chinese children with developmental dyslexia have lower efficiency of word learning in reading, probably this accounts for their less vocabularies in mental lexicon. The findings also have strong implications for educational practice with respect to reading development with dyslexia.
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