Castanea Henryi Research Articles

Spatio-temporal water uptake patterns of tree saplings are not altered by interspecific interaction in the early stage of a subtropical forest

Complementary resource use has often been claimed to explain positive effects of plant diversity on ecosystem functioning, but the underlying mechanisms of complementarity have rarely been directly quantified in forest systems. The aim of this study was to characterize spatial and temporal water uptake of subtropical tree saplings, to assess the role of interspecific interaction on water uptake patterns and to quantify species niche breadth and overlap. Our experiment comprised two deciduous (Castanea henryi, Quercus serrata) and two evergreen tree species (Elaeocarpus decipiens, Schima superba) that were each planted in monoculture and 4-species mixture. We used deuterium-enriched water to trace seasonal water uptake from 5cm and 20cm soil depth. Castanea exploited predominantly the upper soil (74% of overall tracer uptake across treatments) whereas Quercus (50%), Elaeocarpus (57%) and Schima (62%) tended to use both soil layers more equally. Species identity had an overall significant effect on isotopic enrichment in stem water. There was no effect of species richness: niche breadth and overlap of single species was not affected by interspecific interactions in mixtures. Niche overlap between deciduous species was lowest (74%) whereas the two evergreen species had similar water uptake patterns (91%). According to our results, interspecific competition did not alter water uptake patterns of the studied species during the early phase of forest establishment. Thus, soil water uptake complementarity could only occur through inherent (fundamental) specific differences in water uptake niches based on sapling specialization, while phenotypic adjustments to interspecific interaction or neighbor diversity are less important.

Sporogenesis and gametogenesis in Chinese chinquapin (Castanea henryi (Skam) Rehder & Wilson) and their systematic implications

We provide new embryological information regarding the Fagaceae family. Abortive ovules may be a result of mate choice and be necessary to maximize reproductive success in Chinese chinquapin ( Castanea henryi ). In contrast to most angiosperms, in which fertilization occurs 1–2 days after pollination, fertilization in Fagales is delayed from 4 days to more than 1 year. However, the phenomenon of delayed fertilization in Castanea Miller species (Fagaceae), which are the economically important species of Fagaceae and widely distributed or cultured in many countries of the world, has been consistently neglected, raising questions regarding what the delayed fertilization process is and why fertilization is delayed. To answer these questions, we systematically investigated the micro- and megasporogenesis in addition to male and female gametogenesis in Castanea henryi (Castanea Miller species). Our results show that the ovules primordia are immature at the time of pollination and require 6 weeks to become fully developed. During this 6-week period, 32.30 % of ovules abort because of the inability to form an embryo sac (ES). Approximately 15.79 % of ovules abort because of abnormal development of ES. From 7 to 8 weeks after pollination in which double fertilization occurs, most mature ovules are also aborted because of cell degeneration in gametophytes. Only one ovule can develop into a ripe seed. Thus, the delayed fertilization in Castanea henryi may be necessary to increase the time for mate choice and selective fertilization. A certain number of ovule abortions may be the result of delayed fertilization to maximize reproductive success.

New gall wasp species attacking chestnut trees: Dryocosmus zhuili n. sp. (Hymenoptera: Cynipidae) on Castanea henryi from southeastern China.

A new gall wasp species, Dryocosmus zhuili Liu et Zhu, is herein described from the southeastern Fujian province of China. The new species induces galls on trees of Henry’s chestnut, Castanea henryi, which is also a native host for the notorious Oriental chestnut gall wasp (OCGW, Dryocosmus kuriphilus Yasumatsu). D. zhuili overlaps with OCGW in emergence time and induces galls morphologically similar to that of OCGW on similar plant parts. In a previous study, we reported considerable divergence between mtDNA CO1 (mitochondrial DNA Cytochrome c oxidase subunit I) sequences of these wasps and the true OCGW wasps and suggested the existence of a cryptic species. Herein, we confirm the identity of the new species based on morphological and biological differences and provide a formal description. Although the new species is relatively easily separated from OCGW on basis of morphology, field identification involving the two species can still be problematic because of their small body size, highly similar gall morphology, and other life history traits. We further discussed the potential of the new species to be a pest for the chestnut industry and the consequences of accidental introduction of this species into nonnative areas, especially with regard to the bisexual reproduction mode of the new species in contrast to the parthenogenetic reproduction mode of OCGW.

Mechanisms promoting tree species co‐existence: Experimental evidence with saplings of subtropical forest ecosystems of China

AbstractQuestionsThe maintenance of a diverse sapling pool is of particular importance for the regeneration and persistance of species‐rich forest ecosystems. However, the mechanisms of co‐existence of saplings have rarely been studied experimentally. Do species richness, species composition, species identity and stand density affect the co‐existence, growth patterns and crown architecture of tree saplings?LocationJiangxi Province, southeast China.MethodsIn a field experiment, we manipulated the local neighbourhood of saplings of four early‐successional subtropical species (Schima superba,Elaeocarpus decipiens,Quercus serrataandCastanea henryi) with regard to species richness (one, two and four species), species composition (monocultures, six‐two‐species combinations and one‐four‐species combination) and stand density (low, intermediate and high). We tested for treatment effects and impact of species identity on growth variables, biomass allocation, crown architectural traits and branch demography.ResultsSpecies richness was a poor predictor of all response variables, but enhanced pruning and branch turnover. In contrast, species composition proved to be of great importance for growth, biomass allocation, crown architecture and branch demography. Local neighbourhood interactions of saplings were characterized by complementary or facilitative, as well as by competitive mechanisms. Intra‐specific competition was higher than inter‐specific competition for two species (C. henryi,Q. serrata) depending on the respective species combination. To a high degree, the competitive ability of species can be explained by species identity. Competition for light likely played a major role in our experiment, as evidenced by the strong response of crown architecture and branch demography to the manipulated predictor variables.ConclusionsEffects of species composition and species identity on growth rates and crown architecture variables of tree saplings point to niche separation as a mechanism of species co‐existence, while effects of species richness were not yet prominent at the sapling life stage.

Effects of tree sapling diversity and nutrient addition on herb-layer invasibility in communities of subtropical species

Exotic species are assumed to alter ecosystem functioning. However, little is known of the relationships within vertically structured plant communities such as forests, where tree saplings interact with herbaceous species, especially in the early phases of succession. This relationship was tested in a common garden experiment which assessed the impacts on tree saplings and herbaceous species following nutrient addition and the introduction of exotic herb species. The experiment was established in South- East China using four broad-leaved tree species (Elaeocarpus decipiens, Schima superba, Castanea henryi and Quercus serrata) to study the relationships between tree sapling diversity, herb-layer productivity and invasibility. Tree saplings were planted in monoculture and in mixtures of two and four species. A full factorial design was applied, within which species composition was crossed with nutrient and exotic seed-addition treatments. The seed-addition treatment included mixtures of seeds from eight exotic herb species, and herb community attributes were assessed after a four month growing season. Results indicate that certain tree species negatively affect native as well as exotic herbs; however, the high productivity of native herbs had a stronger negative impact on exotic species than tree saplings. Nutrient addition increased the productivity of exotic herbs but had no effect on native herbs. Remarkably, exotic species introduction had a negative feedback effect on the growth of tree saplings, which highlights the potential of exotic herbs to diminish tree recruitment. Although tree saplings reduced invasive effects on the herb-layer during the earliest phase of forest succession, nutrient addition had a more profound and opposite effect on these invaders.

Tree morphology responds to neighbourhood competition and slope in species-rich forests of subtropical China

Trees are able to respond to their local biotic and abiotic environment with morphological adjustments which improve resource acquisition and, thus, growth. In forests, light is broadly recognised as one of the major factors determining growth, and morphological responses comprise changes in crown architecture and stem stature. On sloping terrain, the interplay of phototropism and gravitropism may further affect morphological growth characteristics. However, different tree species are expected to show species-specific responses. In this study, we analysed three growth characteristics of tree individuals belonging to four species of two functional groups (evergreen: Schima superba, Castanopsis eyrei, deciduous: Quercus serrata var. brevipetiolata, Castanea henryi) in a species-rich Chinese subtropical forest. Crown projection area, relative crown displacement and stem inclination were related to biotic (local species richness, functional richness, competition, stand age) and abiotic (slope aspect and inclination, soil depth) variables in the local neighbourhood of the tree individuals. We hypothesised that (i) there are species-specific differences in the morphological response of crown architecture and stem stature and (ii) that crown size and asymmetry as well as stem inclination are influenced by both, biotic and abiotic factors. In contrast to our expectations we were unable to reveal any species-specific differences in any of the three growth characteristics. The results of mixed effects models showed that crown area was mainly affected by the target tree's dbh and biotic variables related to neighbours (competition, functional diversity), whereas stem inclination was mainly influenced by slope. Relative crown displacement was influenced by both, biotic and abiotic variables. We conclude that growth responses resulting in crown displacement and stem inclination seem to be an important mechanism to ameliorate foraging for light in our study area, but that these responses appear to be species-independent. The interplay of stem inclination and crown displacement allows for a plastic response of tree individuals in biotically and abiotically heterogeneous environments. Our results indicate that forest management in this region should focus on functionally diverse stands which are promoting crown area positively resulting in increased growth rates of individual trees.

ACTIVITIES CHANGE OF AMYLASE IN CHINQUAPIN DURING FRUIT DEVELOPMENT

Chinquapin (Castanea henryi Rehd. & Wils.) is an important fruit species in northern Fujian province. The changes of α-amylase and β-amylase activities were studied. The chinquapin cotyledon and pericarp in different development stages were used. α and β-amylase were determined by spectrophotometer, and the OD (optical density) value were defined as the activity of amylase. The results showed that the α-amylase activity of chinquapin cotyledon increased gradually during fruit developing, whereas the α-amylase activity of chinquapin pericarp appeared the shape of single peak type. The change degree in different breeds was significant, which was related to the autumn difference in 8 breeds. The difference of α-amylase activities between pericarp and cotyledon was significant in same breed. The α-amylase activity in pericarp was higher than that in cotyledon during fruit development prophase, but the relationship between pericarp and cotyledon was reverse during fruit development anaphase. The results suggested that the fruit α-amylase focus on pericarp mainly in development prophase, and it focus on cotyledon in development anaphase mainly. We conferred that α-amylase played an important role in regulating and balancing the form of carbohydrate in fruit. The results showed that the β-amylase activity of chinquapin cotyledon appeared the shape of single peak type. The pericarp β-amylase activity in fruit development prophase was higher than that in anaphase. The pericarp β-amylase activity was always higher than that in cotyledon during fruit development. The β-amylase activities were always higher than α-amylase in Pericarp and cotyledon, showing that amylum degradation relied on β-amylase mainly.

Behavioral adaptation of Pallas's squirrels to germination schedule and tannins in acorns

Using acorns from Castanea henryi (CH) and Quercus variabilis (QV) with contrasting germination schedule (related to food perishability) and tannin levels, we conducted field experiments in a subtropical forest in Southwest China to investigate how free-ranging Pallas’s squirrels (Callosciurus erythraeus) utilize acorns as long-term storage based on the food perishability and hightannin hypotheses. Though QV acorns germinated much earlier than CH ones, we found that Pallas’s squirrels hoarded more high-tannin QV acorns over low-tannin CH ones, supporting the high-tannin hypothesis (but not the food perishability hypothesis). However, several other predictions derived from the food perishability hypothesis received sound support: nondormant QV acorns had their embryos removed with a higher probability (68.5%) than dormant CH ones (8.8%) and embryo-removed acorns had a much lower germination success but had a higher probability surviving as long-term storage. During the caching-recovery process, hoarding animals actively detected acorn state (dormant or not) and removed acorn embryos with an increasing probability in subsequent hoarding events. In addition, embryo-removed acorns could serve as long-term storage because they had a very low probability being infested by fungi as intact acorns did during the time of storage. We conclude that tree squirrels can differentially respond to acorn germination and remove the embryos of nondormant acorns more frequently as long-term storage, but tannin level is more important in determining whether a given acorn is hoarded or not. Combined with the studies from North America, our results suggest convergent evolution of acorn hoarding behavior in tree squirrels across different continents. Key words: behavioral decisions, germination schedule, long-term food supply, scatter hoarding, tannins, tree squirrels. [Behav Ecol]

Carbon isotope analysis for source identification of atmospheric formaldehyde and acetaldehyde in Dinghushan Biosphere Reserve in South China

Formaldehyde and acetaldehyde are two most abundant carbonyls in ambient air. Biogenic emission has been proposed as a significant source other than anthropogenic emissions and atmospheric secondary formation. Here at a forest site in South China, the carbon isotopic compositions of formaldehyde and acetaldehyde emitted from leaves of three tree species ( Litsea rotundifolia, Canarium album and Castanea henryi) were measured in comparison with the bulk carbon isotopic compositions of tree leaves. δ 13C data of the emitted aldehydes (from −31‰ to −46‰) were quite different for tree species, which were all more depleted in 13C than the tree-leaf bulk δ 13C values (from −27‰ to −32‰). Formaldehyde in ambient air at the forest site had δ 13C values different from those of leaf-emitted formaldehyde, indicating other sources for ambient formaldehyde apart from direct emission from leaves, most probably the photooxidation of biogenic hydrocarbon like isoprene and monoterpene. The δ 13C differences of acetaldehyde between ambient data and those of tree leaves emission were less than 1‰, implying direct biogenic emission as the dominant source.

Testing the high-tannin hypothesis with scatter-hoarding rodents: experimental and field evidence

With a combination of both experimental (caged, hours/daily) and field (free-ranging, several months) studies, we tested the high-tannin hypothesis that hoarding animals prefer to eat more low-tannin food items immediately but hoard more high-tannin items for later consumption. We studied two common rat species (Edward's long-tailed rat, Leopoldamys edwardsi; and chestnut rat, Niviventer fulvescens) and two nut species (Henry's chestnut, Castanea henryi; and cork oak, Quercus variabilis) that show varying tannin levels (0.6% versus 11.7%) but are similar in other traits. Based on the high-tannin hypothesis, we predicted that (1) both rat species would eat more low-tannin C. henryi nuts instantly but fewer high-tannin Q. variabilis nuts and (2) after harvesting a given nut, they would prefer to hoard more Q. variabilis nuts and fewer C. henryi nuts. The first prediction was firmly supported in our study: both rat species ate more C. henryi nuts than Q. variabilis nuts under all conditions. However, the second prediction was supported only in the field study, which lasted over several months, in contrast to the experiments conducted in seminatural enclosures (only 1 day). We found that high-tannin Q. variabilis nuts, in contrast to low-tannin C. henryi nuts, had a significantly higher probability of being hoarded and surviving as seedlings in the field. We conclude that experimental conditions used here are less likely to result in natural feeding preferences of tested animals and the high-tannin hypothesis is supported especially in the field setting.

The effect of low-temperature storage on the activity of polyphenol oxidase in Castanea henryi chestnuts

Abstract Chestnuts of Castanea henryi (Skan) Rehd. et Wils were stored at 4 and −20 °C for a duration of 6 months. The effects of such storage treatments on the polyphenol oxidase (PPO) activity and total free phenolics content were investigated. Total phenolics content showed uneven distribution in C. henryi chestnuts. The chestnut PPO was isolated and characterized in terms of optimum temperature (40 °C), optimum pH (5.0), substrate specificity (catechol most efficient) and relative molecular weight (69.0 kDa). The PPO specific activity decreased from ca. 1180 to 340 U mg −1 for chestnuts stored at 4 °C and to ca. 300 U mg −1 for those stored at −20 °C. The PPO activity and the storage temperatures in this investigation showed a significant ( P P

Purification and characterization of polyphenol oxidase from Henry chestnuts (Castanea henryi)

Polyphenol oxidase from Castanea henryi nuts was partially purified. Some characteristics of the enzyme were then determined to help devise measures for the prevention of undesirable enzymatic browning during storage and processing of the nuts. Preparation of acetone powder extracts of the nuts, ammonium sulfate precipitation, dialysis, and gel filtration resulted in 37-fold purification of the enzyme with a yield of 13%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the excitation spectrum confirmed the enzyme preparation to be homogeneous. The approximate molecular weight of the enzyme was determined by gel filtration to be 69 kD. The enzyme catalyzed the oxidation of catechol and pyrogallic acid as substrates but did not affect cresol or tyrosine. Using catechol as substrate, p-nitrophenol, thiourea, orcinol, and naphthol showed strong inhibition. The optimal pH and temperature for the enzyme were pH 5.0 and 40°C, respectively. The enzyme proved heat labile. When the enzyme was incubated at 70°C for 30 min, the remaining activity of the enzyme was only 8%. Possible approaches to applying the results of this study to the prevention of enzymatic browning in the production of C. henryi nuts is also discussed.