Castanopsis Hystrix Research Articles

Soil-atmosphere exchange of greenhouse gases in subtropical plantations of indigenous tree species

Indigenous broadleaf plantations are increasingly developing as a prospective silvicultural management approach for substituting in place of large pure conifer plantations in subtropical China. However, little information is known about the effects of tree species conversion on soil-atmosphere greenhouse gas (GHG) exchanges. Four adjacent monospecific plantations were selected in subtropical China to examine the effects of tree species on soil-atmosphere exchanges of N2O, CH4 and CO2. One coniferous plantation was composed of Pinus massoniana (PM), and the three broadleaf plantations were Castanopsis hystrix (CH), Michelia macclurei (MM) and Mytilaria laosensis (ML). We found that mean soil N2O and CO2 emissions in the PM plantation were 4.34 μg N m−2 h−1 and 43.25 mg C m−2 h−1, respectively, lower than those in the broadleaf plantations (>5.25 μg N m−2 h−1 and >56.38 mg C m−2 h−1). The PM plantation soil had higher mean CH4 uptake (39.03 μg C m−2 h−1) than the broadleaf plantation soils (<32.67 μg C m−2 h−1). Variations in soil N2O emissions among tree species could be primarily explained by the differences in litter C:N ratio and soil total N stock. Differences in soil CH4 uptake among tree species could be mostly attributed to the differences in mean soil CO2 flux and water filled pore space (WFPS). Litter C:N ratio could largely account for variations in soil CO2 emissions among tree species. This study confirms that there is no GHG benefit of converting PM plantation to broadleaf plantations in subtropical China. Therefore, the future strategy of tree species selection for substituting in place of large coniferous plantations in subtropical China needs to consider the potential effects of tree species on soil-atmosphere GHG exchanges.

Correlation between leaf litter and fine root decomposition among subtropical tree species

Elucidating the processes of leaf litter and fine root decomposition has been a major research focus, while how the correlation between leaf litter and fine root decomposition is unclear. We studied the in situ decomposition and N dynamics of leaf litter and fine root of four subtropical tree species (Pinus massoniana, Castanopsis hystrix, Michelia macclurei and Mytilaria laosensis) to determine whether leaf litter and fine root decomposition is correlated across species as well as which factors influence decomposition above versus below ground. Decomposition rate of leaf litter was related to that of fine root across species. The strong correlation between leaf litter and fine root decomposition rates arose largely for several reasons. First, soil moisture had the similar influences on both leaf litter and fine root decomposition rates. Second, traits (i.e., initial Ca concentration) important to both leaf litter and fine root decomposition rates showed significant similarity among species. Third, initial P, N and aromatic C concentrations, and C/N ratio were uniquely important for fine root decomposition rate, while no unique traits for leaf litter decomposition rate. This also could account for the strong correlation between leaf litter and fine root decomposition rates. Our study suggests that among these subtropical trees, species effects on in situ decomposition rates of leaf litter and fine root are very similar. Thus, species differences in decomposition rates may be as large as they would be if faster decomposition of leaf litter was correlated with faster decomposition of fine root. N immobilization rate of leaf litter was unrelated to that of fine root across species. Our results help explain some important mechanisms by which tree species influence litter in situ decomposition.

Effects of elevated CO2 and N deposition on plant biomass accumulation and allocation in subtropical forest ecosystems: a mesocosm study.

Aims Interactive effects of elevated atmospheric CO2 concentration (CO2) and nitrogen (N) deposition on terrestrial ecosystems play an important role in global carbon cycling. Ecosystems in subtropical and tropical areas occupy a large percent of the global biomass, but few studies have been done in these areas. Therefore, our objective was to conduct an experiment to improve our understand- ing of atmospheric (CO2) enrichment and N deposition effects on biomass accumulation and allocation in subtropical and tropical forests. Methods A model forest ecosystem was constructed of five tree species native to South China: Schima superba, Castanopsis hystrix, Ormosia pinnata, Acmena acuminatissima and Syzygium hancei. The species were exposed to a factorial combination of elevated CO2 and high N deposition in open-top chambers beginning March 2005. There are four experimental treatments, including CN (elevated (CO2) of (700±20) μmol⋅mol -1 and high N of 100 kg N⋅hm -2 ⋅a -1 ), C+ (elevated (CO2) of (700±20) μmol⋅mol -1 and ambient N), N+ (ambient (CO2) and high N of 100 kg N⋅hm -2 ⋅a -1 ) and CK (ambient (CO2) and am-

A scientific assessment of traditional knowledge on firewood and fodder values in Sikkim, India

Communities in the Yuksam-Dzongri trekking corridor of Sikkim use a wide variety of plant species as firewood and fodder with species preferences based on their local knowledge. Current practices are increasing harvest pressures on good quality firewood and fodder plants leading to deteriorating forest condition along the trekking corridor. To help develop management strategies and to ensure the long term sustainability of forest resources in this region, it is important to understand local peoples’ basis for their species preferences. In this paper, we compared people's preferences for species used as firewood and fodder using Participatory Rural Appraisal (PRA) tools with data on these species’ chemical constituent properties to better understand the rationale for local preferences. Sixteen woody trees species ( Rhododendron arboreum, Rhododendron falconeri, Rhododendron barbatum, Quercus lamellosa, Q. lineate, Schima wallichii, Prunus cerasoides, Prunus nepalensis, Castanopsis hystrix, Beilschmiedia sikkimensis, Acer oblongum, Betula alnoides, Eurya acuminate, Symplocos ramosissima, Alnus nepalensis and Litsaea elongate) and twenty-three fodder plants (including Thysanolaena maxima, Ficus nemoralis, Q. lamellosa, Imperata cylindrical, and Saurauia nepaulensis), the most widely used species in the area, were selected for study. The tree species were evaluated for their wood properties (calorific value, wood density, moisture and ash content) based on the Firewood Value Index (FVI), and fodder species for their nutritional qualities (dry matter, nitrogen and crude protein, and fat content). Most of the highly preferred species were found to have high values for firewood or fodder properties, and a significant correlation was found between the community scores and the FVI and some fodder attributes, namely dry matter and protein content. The study illustrates the applicability of local knowledge in relation to the chemical properties of species used for firewood and fodder.

Facilitation by two exotic Acacia: Acacia auriculiformis and Acacia mangium as nurse plants in South China

Because of their high growth rate and tolerance to bare soil, two exotic Acacia species, Acacia auriculiformis and Acacia mangium, have been commonly planted in degraded areas of South China. With their large canopies and ability to fix nitrogen, the two Acacia species have also been considered to act as nurse plants for understory plants. The current study clarified the nursing effects of the Acacia species by comparing microclimate characteristics and physiological traits of native plant seedlings at three sites: under the canopies of the each Acacia species and on bare land (open site). Although the sites were not replicated, the results indicated that adult trees of both Acacia species can facilitate native species, but that A. mangium has greater facilitating effects due to greater temperature buffering, radiation reduction, and nutrient amelioration. In response to facilitation, three species ( Castanopsis hystrix, Michelia macclurei, and Manglietia glauca) with different shade-tolerant traits growing under Acacia canopies expressed distinct adaptations. For the three species, the chlorophyll fluorescence curves of rETR and Δ F/Fm′ were higher under A. auriculiformis and on the open site than under A. mangium. The maximum quantum yield in PSII(Fv/Fm) in diurnal changes of the three species showed that all the Fv/Fm values were between 0.70 and 0.84 and that the Fv/Fm values were mostly higher under A. mangium than on the open site or under A. auriculiformis. Total chlorophyll content and both chlorophyll a and b contents in the three species were higher under the Acacia species than on the open site, while chlorophyll a/b ratio was higher on the open site. In contrast, the carotenoid content in C. hystrix and M. macclurei was lower under the two Acacia species than on the open site, while the opposite was true for M. glauca. The results demonstrate that the adaptation of the understory species to abiotic environmental factors is not restricted to a single mechanism but apparently involves a group of interrelated, adaptive suites. And also these adaptations were species-specific and especially related to their shade tolerance.

Ecology of seed germination of eight non-pioneer tree species from a tropical seasonal rain forest in southwest China

We compared various aspects of the seed biology of eight non-pioneer tree species from a tropical seasonal rain forest in Xishuangbanna, SW China, that differ in time of dispersal, size and fresh seed moisture content (MC). Seeds were tested for germination under laboratory conditions after dehydration to different moisture levels and under 3.5, 10 and 30% solar irradiances in neutral-shade houses. For six species, germination was also compared in forest understory (3.5% light) and center of a forest gap (32.5% light). Under continuous dehydration over activated silica gel, 100% of seeds of four species had lost the ability to germinate after 48 h, and those of all species except Castanopsis hystrix (decreased from >90 to 30% germination) had lost the ability to germinate after 120 h. Four species did not differ in final germination percentages at the three irradiances (i.e. uniform germination). However, final germination percentages of Horsfieldia pandurifolia and Litsea pierrei var. szemaois were significantly lower in 30% than in 10 or 3.5% light, and seeds of Antiaris toxicaria and C. hystrix germinated to higher percentages in 30 and 10% than in 3.5% light. Mean time to germination (MTG) of the eight species (forest and shade house data combined) ranged from 5–5 days for Pometia tomentosa to 72–207days for L. pierrei; MTG for four species was ≤21 days. There was no obvious relationship between relative desiccation resistance and either time of dispersal, MTG or uniformity of germination at the three light levels, or between seed size and MC or MTG. However, the relationship between seed MC at maturity (25–60% fresh mass basis) and MC at 50% loss of seed viability (12.4–42.5%) was significant. Seven of the species fit Garwood’s (Ecol Monogr 53:159–181, 1983) rapid-rainy germination syndrome and one, L. pierrei, either her delayed-rainy or intermediate-dry germination syndrome. However, fresh, non-dehydrated seeds of all eight species germinated in ≤30 days at constant 30°C in light.

Effects of moderate high-temperature stress on photosynthesis in three saplings of the constructive tree species of subtropical forest

During the exposition to moderate high-temperature stress, photosynthetic rates and fluorescence of chlorophyll a were measured with a photosynthetic measurement system (Li-Cor 6400) and leaf chamber fluorometer (Li-Cor6400 LCF), respectively, in leaves of saplings, sun-adapted species ( Schima superba), shade-adapted species ( Cryptocarya concinna), and in mesophytic plant ( Castanopsis hystrix) (42°C). The results showed that moderate high-temperature stress led to a decrease in F v/ F m, namely the primary photochemical quantum efficiency, indicating that moderate high-temperature stress causes a partial inhibition of PSII. It also showed that such an effect was more severe in the shade-adapted plant C. concinna than in the sun-adapted species S. superba. However, except for the sun-grown leaves of C. concinna, the moderate high-temperature stress increased the photosynthetic rate of leaves at high light intensity. Simultaneously, less photoinhibition was found to occur under high-light intensity, suggesting that the capacity of resistant-photoinhibition was stimulated by moderate high-temperature stress. The quantum yield of PSII (ϕ PSII) decreased in the sun-grown leaves of S. superba and C. hystrix but did not show any significant change in leaves of the shade plant C. concinna and shade-grown leaves of sun plant S. superba or the mesophytic plant C. hystrix because they already had a very low ϕ PSII under this condition. Moderate high-temperature stress led to a decrease in ϕ PSII/ϕ CO 2 ratios, an estimate of the quantum requirement for CO 2 assimilation, in the sun plant S. superba and the mesophytic plant C. hystrix because they were associated with the dissipation of a lower fraction of excitation energy. However, no significant changes were found in shade plant C. concinna and in shade-grown leaves of the other examined plants. The effect of moderate high-temperature (42°C) on photosynthesis depends on species and leaf type (sun and shade leaves) in the saplings of subtropical broad-leaved trees.