Tropical Rainforest In Xishuangbanna Research Articles

Isoprenoid emissions of trees in a tropical rainforest in Xishuangbanna, SW China

Isoprenoid emissions of eight tropical tree species of SE Asia were investigated using dynamic Teflon bag branch enclosures. Emission potentials of four species were considerably deviating from a previous report. Two species, Garcinia cowa and Celtis philippensis, emitted isoprene with standard emission factors, given as carbon on dry weight basis of 20.7 and 0.2 μ g g - 1 h - 1 , respectively, before the peak of the rainy season. After the peak of the rainy reason the standard emission changed to 17.5 and 0.7 μ g g - 1 h - 1 , respectively. The other six species emitted monoterpenes with low standard emission factors between < 0.1 and 0.5 μ g g - 1 h - 1 . Four out of five species investigated at two different times of the year showed seasonal differences in emission rates and composition. Total isoprenoid emissions were generally higher with new leaf flush than with aged leaves. Overall, the results suggest that better understanding of volatile organic compounds (VOC) emission from tropical species of SE Asia requires investigations that cover different seasons.

Occurrence and morphometric variability in the frugivorous bat species, Cynopterus sphinx and Rousettus leschenaulti, from a tropical rainforest, Xishuangbanna, SW-China

Occurrence and morphometric variation were recorded over one and a half years for two species of frugivorous bats, Cynopterus sphinx and Rousettus leschenaulti, from six localities in and around a tropical rainforest in Xishuangbanna, SW-China. Occurrence of both species was simultaneous. The two species breed all throughout the year, but we found one distinct peak in breeding season for each species. Although the overall morphology between the two species did not differ significantly, statistical analysis of morphological characters revealed consistent spatial correlations for both taxa. Body size and forearm length for both univariate and multivariate analyses (as derived from principal component analysis) was strongly and positively correlated with morphometric variations across the locations for C. sphinx and R. leschenaulti. Both, the different peaks in breeding season and the consistent spatial correlations suggest mechanisms to help resource partitioning. The study represents the first species documentation from this area.

Geological History, Flora, and Vegetation of Xishuangbanna, Southern Yunnan, China1

ABSTRACTXishuangbanna of southern Yunnan is biogeographically located at a transitional zone from tropical Southeast (SE) Asia to subtropical East Asia, and is at the junction of the Indian and Burmese plates of Gondwana and the Eurasian plate of Laurasia. The flora of the region consists of a recorded 3336 native seed plant species, belonging to 1140 genera in 197 families, among which 83.5 percent are tropical genera and 32.8 percent are endemic to tropical Asia, suggesting a strong affinity to tropical Asian flora. The vegetation of Xishuangbanna is organized into four forest types: tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad‐leaved forest, and tropical monsoon forest. The tropical rain forest in Xishuangbanna has the same floristic composition of families and genera as some lowland equatorial rain forests in SE Asia, and is dominated (with a few exceptions) by the same families both in species richness and stem dominance. The exceptions include some deciduous trees in the canopy layer, fewer megaphanerophytes and epiphytes, and a higher abundance of lianas and microphyllic plants. We consider the tropical rain forest of Xishuangbanna as a type of tropical Asian rain forest, based on their conspicuous similarities in ecological and floristic characteristics.

Patterns of fruit traits in a tropical rainforest in Xishuangbanna, SW China

Abstract As a basis for determining how vertebrate frugivores influence the evolution of tropical fruits, we investigated distribution patterns of different fruit traits that are known to influence frugivore food choice, drawing on data gathered from 626 plant species in a primary tropical rainforest at Xishuangbanna, SW China. Species with fleshy fruits are common (66%) in the forest; the proportion of fleshy fruits differed among different growth forms: canopy trees (63%), subcanopy trees (83%), shrubs (74%), lianas (67%), herbs (65%) and epiphytes (49%). Dry fruits had a higher frequency of small-seeded species (length of seed 50 mm). As a whole, black fruits were most common (40% of 389 species), followed by fruits with red, brown, yellow and bicolored (19%, 13%, 13% and 8%, respectively); green, white, and blue fruits were relatively rare (4%, 2% and 1%, respectively). Characteristics of small fleshy fruits included thin husks, red, white, or black colors and a few medium-sized seeds (2–10 mm). Many medium-sized fruits had large, well-protected seeds. The distribution of plant species among various fruit and seed categories is non-random in this forest. Nested ANOVA revealed a significant phylogenetic component in the variances of most fruit traits while fruit size and color showed 39.7–48.1% of within-genus variances from non-phylogenetic factors.

SPECIES DIVERSITY DYNAMICS OF FRAGMENTED TROPICAL RAINFORESTS IN THE LOWER-LANCANG/UPPER-MEKONG RIVER BASIN

Three fragments of tropical rainforest in Xishuangbanna, southern Yunnan and within the Lower-Lancang/Upper-Mekong River basin, were sampled to investigate species diversity patterns based on comparisons with a contiguous tropical rainforest. Compared with the contiguous forest, the fragments were lower in plant abundance, species diversity indicies, a lower percentage of mega-phaenerophytes, meso-phaerierophytes, chamaephytes and epiphytes, but had a higher percentage of liana, micro-phaenerophytes and miniphacncrophytcs. Thc floristic composition was also different in the fragments with a greater percentage of pan- tropical and tropical Asia to tropical Africa elements increased, whereas the percentage of regional or local elements decreased. Meanwhile, tree species in the upper canopy layer were more stable than that in the lower layers of the fragmented forest. The animal species diversity and evenness were higher in the contiguous forest than in the fragmented forests, which apparently were due to better habitat size and quality. The relationship between changes in the microclimate of the forest fragments and species changes were also considered. The interior forest of the fragmented forests transformed from a wet-cool to dry-warm microclimate, called the internal effect, and was found to be an important mechanisms accounted for observed species changes.

Pollination Biology of Ficus Auriculata Lour.in Tropical Rainforest of Xishuangbanna

Ficus auriculata Lour. is a widely distributed and common species in the tropical rainforests in Xishuangbanna, China. The pollination of Ficus auriculata is done by Ceratosolen emarginatus Mayr, their unique symbiotic associates. The fig_pollination wasps cannot develop anywhere except in the host syconia, and so both are highly co_evolved mutualists that depended completely on each other for propagation. The present paper reported on the growing character of syconia and flowering phenology of Ficus auriculata , as well as the pollination behavior, regularity of fig visitation and pollination efficiency of Ceratosolen emarginatus based on our observations in the rainforests of Xishuangbanna, southern Yunnan, China. Ficus auriculata is a dioecious plant that bore fruit all year round in the population, with two fruit_bearing peaks on the female trees and one fruit_bearing peak on the male trees. The male trees produced pollen and provided fig wasps with havens, while the female trees produced fig seeds after pollination by fig wasps. The reproduction of Ceratosolen emarginatus varied with foundress number of females entering into a syconium in different seasons. The fruit_bearing peaks of female trees appeared from April to June and from September to November each year, and foundress number per syconium also peaked during these periods. Male trees bore the most fruits in January, however, due to the number restriction of fig wasps, the foundress number entering into a male syconium was low; its peak was postponed between 25th of March and 10th of April, when some syconia had matured. In order to ensure reproductive success, Ficus auriculata has evolved three out_breeding mechanisms: dichogamy, gynodioecy and incompatibility of short_style female flower. Ceratosolen emarginatus visited syconia when female flowers were blossoming, and entered into the fig cavity to lay eggs or pollinate pollen. The fig wasps' behavior of visiting syconia was controlled by temperature and humidity: the fig wasps actively visited receptive syconia when temperature and humidity varied mitigatively in the morning and afternoon; few fig wasps flew at noon. The optimum temperature was 20_24 ℃ and optimum humidity was 85%_93%. The fig wasps stopped hovering if the temperature was over 29 ℃, humidity was less than 58% or the weather was windy and rainy. The visiting peak of fig wasps appeared at different times in four seasons, it appeared at 10∶00 in spring, 7∶40 in summer, 11∶00 in autumn and 13∶00 in winter. The pollination efficiency of Ceratosolen emarginatus was examined by introducing eight, ten and fifteen fig wasps to a female syconium. The pollination ratio was the highest when mean eight fig wasps enter into a syconium. The mean percentage of seed was 50.8%. Mean seed ratio reached 37.2% if only four foundresses pollinate a syconium and 44.4% with ten foundresses. The result showed no difference with natural syconium of the same foundress number.

Soil Nutrient Contents and Their Characteristics of Seasonal Changes Under Shorea chinensis Forest in Xishuangbanna

Shorea chinensis forest of Xishuangbanna (21°29′ N, 101°34′ E) is a rainforest type of tropical rainforest in South_east Asia entering into Xishuangbanna, which is significant in connecting with the flora of tropical rainforests in South_east Asia and elucidating characteristics of tropical rainforest in Xishuangbanna. In southern Mengla county, Xishuangbanna, Shorea chinensis forest grows on the mountain in altitude 700_900 m, the soil is latosol, annual mean temperature is 21.1 ℃, and annual mean precipitation is 1 500_1 600 mm. In order to know the soil nutrient content, organic matter, total N, P, K, available N, P, K and their seasonal changes under Shorea chinensis forest in Xishuangbanna, we took soil samples in the top soil (0_10 cm) and under the top soil (10_25 cm) from 47 plots among 10 different patches of Shorea chinensis forest in May and November, 1999. 23 plots were located in valleys and 24 plots in lower mountainous areas. The results showed there are obvious difference in the soil nutrient content in different soil layers, in different seasons and in different areas: 1) in different soil layers, nutrients were rich in the top soil (0_10 cm) and poor under 10 cm depth. The content of nutrients under 10cm depth was about 56%_75% of the nutrients in top soil; available P content was only 0.039% of the nutrients in top soil. 2) Soil nutrient content changes with seasons; nutrients were higher before the rainy season than after the rainy season. The content of organic matter, total N, total P and total K in top soil after rainy season was 94%, 90%, 94% and 82% of the content before rainy season respectively, and the content of available N and available K in top soil after rainy season was 89%, 92% of the content before rainy season. Available P decreased sharply in top soil after rainy season; the content of available P in top soil after the rainy season was only 0.078% of the content before the rainy season. The change in nutrient content under top soil after rainy season was the same as the change in nutrient content in top soil. 3) Concerning soil nutrient content in different area, nutrients were also higher in valleys than in lower mountainous areas. The content of organic matter, total N, total P and total K in top soil in lower mountainous area were 79%, 80%, 84% and 83% of the content in valley respectively, while the content of available N, available P and available K were also lower in top soil in lower mountainous area than in valleys. From the above results, we can conclude that seasonal changes significantly affected total K and available P, but only slightly affected total P, available K and organic matter, and affected N content more in lower mountainous areas than in valleys. In the rainy season P content in soil is very poor. The environment and plant growth rhythm of Shorea chinensis forest have some effects on the soil nutrient content.

Impact of Disturbance of Planting Amomum villosum in Tropical Seasonal Rainforest on Forest net Primary Productivity in Xishuangbanna

Xishuangbanna, located in south Yunnan, southwest China, is the northern border of the tropical zone. It maintains large areas of tropical rainforest called tropical seasonal rainforest. Like most tropical rainforests all over the world, these tropical seasonal rainforests are under high pressure of long_term disturbance caused by forest utilization. Amomum villosum, a shade_tolerant perennial herb, prefers to grow in forest gaps. It is one of the main cash crops of local people as its fruit is widely used in Chinese traditional medicine. It has been widely planted in tropical seasonal rainforest understorey in Xishuangbanna. To promote its growth and fruit yield by raising the light level of habitat, the forest shrub and herb layers are cleaned and about 60% 70% of trees are thinned. As a result, A. villosum planting has become the most serious disturbance to the tropical seasonal rainforest. Net primary productivity ( NPP ) is the primary element of nutrient cycling and energy flow within an ecosystem. It reflects the ability of a plant community to use natural resources. Most of the studies on forest NPP change after disturbance have focused on secondary forest, and few studies report the impact on NPP of forest canopy damage. This paper aims to determine the effect of A. villosum planting on forest NPP , and to study if that disturbance is the current most important limiting factor on NPP of the rainforest in Xishuangbanna. The study was carried out at Menglun, Xishuangbanna. Three primary seasonal rainforest sites and three disturbed rainforest sites with A. villosum plantation were chosen for the study and one 0.25 hm 2 plot was established at each site. All six study sites were distributed along ravines, within 21°55′ 21°59′N,101°08′ 101°13′E and at altitude of 650 800 m. Pometia tomentosa is the dominant tree species of the top tree layers at all research sites. At each plot, all trees and lianas with diameter at breast height ( DBH ) ≥5 cm were numbered and marked at breast height, and their DBH were measured annually. The biomass ( B ) and its annual increment ( ΔB ) of the research plots was estimated using the allometric regression equation relating tree mass to DBH of Xishuangbanna tropical rainforest. The amount of dead wood on all plots was recorded annually. At the same time, 20 litter fall traps were placed at each plot and litter was collected every half month. Leaf herbivory was measured by leaf samples and the total leaf herbivory ( G ) was estimated through annual leaf litterfall. The primary net productivity was calculated using the NPP equation NPP = ΔB+L+G, in which L is annual litterfall together with dead wood. The shrub and herb biomass were determined by the harvest method and their biomass increment was estimated by biomass divided by age. The biomass increment for shrub and herb was approximate to NPP . The results show that the annual mean NPP (mean±SE) of the primary rainforest is 23.47±2.12 t·hm -2 ·a -1 , with 22.04±2.09 t·hm -2 ·a -1 in the tree layer, 0.75±0.08 t·hm -2 ·a -1 in the shrub layer, 0.43±0.05 t·hm -2 ·a -1 in woody liana and 0.25±0.03 t·hm -2 ·a -1 in the herb layer. The allocation of NPP of the tree layer was: for litterfall, 11.75±0.54 t·hm -2 ·a -1 ; for tree fall, 0.62±0.21 t·hm -2 ·a -1 ; for leaf herbivory, 0.66±0.05 t·hm -2 ·a -1 ; and for biomass accumulation, 9.01±2.70 t·hm -2 ·a -1 . Compared to the primary rainforest, the NPP of the tree layer, shrub layer, woody liana and total community of the disturbed rainforest decreased 26.1%, 65.7%, 86.1% and 22.5% respectively, but the herb NPP increased 536% because of the dominance of A. villosum. Similarly, litterfall and biomass accumulation of the tree layer decreased 25.5% and 53.4% respectively. The tree fall increased 356% relative to the primary forest due to the change of microenvironment after disturb

Restoration of Tropical Rainforest After Removing Amomum villosum in Xishuangbanna

The effects of Amomum villosum cultivation on biodiversity in Xishuangbanna tropical rainforest attract much attention. This research, which lasted two years, was carried out to study ecological restoration after removal of Amomum villosum in the rainforest of Xishuangbanna. The results were as follows: 1) the number of plants in the rainforest increased significantly, compared with the number in primary rainforest, which has the same type of vegetation but has never been planted with Amomum villosum . However, there are no significant differences between the two kinds of rainforests as to the species richness, plant diversity and evenness, which have increased prominently in both kinds of rainforests. The flora develops to that of tropical rainforest. The dominant species is not prominent, but the number of herbs and ferns increases significantly. 2) in the wet season, the seedlings grow faster in removed Amomum villosum rainforests than in primary rainforests, but there is no difference in dry season growth. The biomass of seedlings reached (636.1±43.4) g·m -2 after two years, exceeding that of primary rainforest, especially due to the fast growing herbs and ferns; 3) water content of soil was improved, as was the water capacity, with no difference to that of primary rainforests. The organic matter content of deep soil increased significantly, while the available phosphorus content needed long_time vegetation restoration to increase. Much of the available phosphorus of the surface was lost by the stream_water of rain. A new pattern of Amomum villosum rotation in tropical forests was recommended, which would be a good approach to the minority of mountain area in Xishuangbanna, because it could partly harmonize the contradiction between conservation and development.

Nutrient cycling in a tropical seasonal rain forest of Xishuangbanna, Southwest China. Part 1: tree species: nutrient distribution and uptake

Tropical rain forests are characterized by large numbers of the species with diverse growth habits. The objective of the present study was to determine the distribution of nutrient content in the major trees of the tropical rain forests in Xishuangbanna. This will improve the understanding of the nutrient losses from such sites that result from harvesting and flow of nutrients within the ecosystem and lead to the development of effective and rational forest management strategies. Based on the results in this study, the distribution of nutrients among biomass components of trees varied: The ordering of major elements concentrations was K>N>Mg>Ca>P in branch, stem and root tissues but was N>K>Mg>Ca>P in leaves. The maximum amount of all nutrients per ha occurred in the stems followed by branches, roots and leaves. Of the total uptake of 6167.7 kg ha −1 of all nutrients, the contribution of various nutrients was found to be N (2010.6 t ha −1), P (196.3 t ha −1), K (2123.8 kg ha −1), Ca (832 kg ha −1) and Mg (1005 kg ha −1). However, comparing the nutrient uptake of other tropical and sub tropical forests, the results indicated that rates for the Xishuangbanna forests were 20–35% lower than previously reported values.

Arbuscular mycorrhizal status of plants and the spore density of arbuscular mycorrhizal fungi in the tropical rain forest of Xishuangbanna, southwest China

The arbuscular mycorrhizal status of 112 plant species and the spore density of arbuscular mycorrhizal fungi (AMF) in the rhizosphere soil of these plants in the tropical rain forest of Xishuangbanna, southwest China, were surveyed. It was found that 56% of the surveyed species were arbuscular mycorrhizal, 31% were possibly arbuscular mycorrhizal and 13% were non-mycorrhizal. The spore density of AMF ranged from 55 to 1,908 per 100g soil, with an average of 476. The rhizosphere soil from the arbuscular mycorrhizal plants did not always have a higher AMF spore density than that from the possibly mycorrhizal and non-mycorrhizal plants. The clumped distribution of AMF spores and the complex structure of the underground component of the tropical rain forest may be two important factors that affected the spore density of AMF. Fungi belonging to the genera Acaulospora and Glomus are the dominant AMF in the soil of the tropical rain forest of Xishuangbanna.

The floristic characteristics of the tropical rainforest in Xishuangbanna

The general floristic characteristics of the tropical rainforest of Xishuangbanna have been summarized in the present paper. The tropical rainforest is estimated to consist of more than 3,000 species of seed plant pertaining to more than 1,000 genera and about 180 families. Based on the comprehensive analysis of the distribution of taxa in two representative communities of the rainforest, the deduction is given as follows: the families, genera and species of tropical distribution take up about 80%, 94% and more than 90% of the total of the flora separately in which the genera of tropical Asia take up 33%–42% of the total and the species of tropical Asia take up about 74% of the total. The flora is explicitly of tropics in nature and as a part of tropical Asian flora. Occurring at the montane habitats of northern margin of tropical SE Asia, the flora also embodies conspicuous characters of marginal tropics. Xishuangbanna is geographically a transitional area from true tropics to subtropics and an ecotone where the floristic element of Indo-Malaysia from south, the one of S Asia or S Himalayas from west, the one of Indochina-S China from southeast and the one of S China from northeast meet and overlap in their areal boundaries each other. The flora is therefore endosed with the characteristics of floristic ecotone.

The tropical rainforest vegetation in Xishuangbanna

The tropical rainforest in Xishuangbanna, Yunnan Province of China, is introduced in detail in this paper. Situated at the northern margin of tropical mainland SE Asia and controlled by monsoon climate, the region has been climatically at the lower limits for tropical rainforests, however true tropical rainforests exist and develop luxuriantly in the region. The reasons for this are discussed. In general phytocoenological characteristics such as vertical stratification, life form spectrum, species riches etc. the tropical rainforest in Xishuangbanna is very similar to the typical tropical rainforest in equatorial region, but it is characterized by a clear change of physiognomy between different season. As occurred at the latitudinal and altitudinal limits of tropical rainforest, the flora of the rainforest is endowed with the nature of northern margin of tropical zone of SE Asia and is transitional toward the flora of subtropical forest of China. In recent years the region has been opened up to use in a large scale and the primary forests, especially rainforests, have been severely destroyed. The conservation and research to the tropical rainforest are very urgent and have to be done at once.

The Effect of Hooded Crows on Hill Sheep Farming in Argyll, Scotland: The Food Supply of Hooded Crows

The stand biomass and primary net productivity of artificial tropical rainforest in Xishuangbanna were estimated, based on sample tree method and harvesting method. The results showed that the standing biomass was 390.4 t.hm-2, of which, 362.5 t.hm-2(92.8%) were contributed by tree layers. The biomass of shrub and inter-layer plants (including epiphytes) was 19.3 t.hm-2(4.9%) and 3.6 t.hm-2(0.9%), respectively, and that of herbaceous layers was 5.0 t.hm-2. The primary net productivity of the stand was 2227.3 g.m-2.yr-1, of which, 1553.5 g.m-2.yr-1(69.7%) were contributed by tree layers. In the allocation of primary net productivity in different parts of trees stems showed the highest net productivity, accounted for 42.0%. Leaves and branches were accounted for 30.2% and 13.5%, respectively. The leaf area index (LAI) was 7.061. The optimum regression models of different dominant plants and organs of the sample trees of tree layer in the artificial tropical forest were built.