Hyperglycemia and blood glucose deterioration are risk factors for severe COVID-19 with diabetes: A two-center cohort study.

We aimed to assess whether blood glucose control can be used as predictors for the severity of 2019 coronavirus disease (COVID-19) and to improve the management of diabetic patients with COVID-19. A two-center cohort with a total of 241 confirmed cases of COVID-19 with definite outcomes was studied. After the diagnosis of COVID-19, the clinical data and laboratory results were collected, the fasting blood glucose levels were followed up at initial, middle stage of admission and discharge, the severity of the COVID-19 was assessed at any time from admission to discharge. Hyperglycemia patients with COVID-19 were divided into three groups: good blood glucose control, fair blood glucose control, and blood glucose deterioration. The relationship of blood glucose levels, blood glucose control status, and severe COVID-19 were analyzed by univariate and multivariable regression analysis. In our cohort, 21.16% were severe cases and 78.84% were nonsevere cases. Admission hyperglycemia (adjusted odds ratio [aOR], 1.938; 95% confidence interval [95% CI], 1.387-2.707), mid-term hyperglycemia (aOR, 1.758; 95% CI, 1.325-2.332), and blood glucose deterioration (aOR, 22.783; 95% CI, 2.661-195.071) were identified as the risk factors of severe COVID-19. Receiver operating characteristic (ROC) curve analysis, reaching an area under ROC curve of 0.806, and a sensitivity and specificity of 80.40% and 68.40%, respectively, revealed that hyperglycemia on admission and blood glucose deterioration of diabetic patients are potential predictive factors for severe COVID-19. Our results indicated that admission hyperglycemia and blood glucose deterioration were positively correlated with the risk factor for severe COVID-19, and deterioration of blood glucose may be more likely to the occurrence of severe illness in COVID-19.

The effect of allometric partitioning on herbivory tolerance in four species in South China.

Herbivory tolerance can offset the negative effects of herbivory on plants and plays an important role in both immigration and population establishment. Biomass reallocation is an important potential mechanism of herbivory tolerance. To understand how biomass allocation affects plant herbivory tolerance, it is necessary to distinguish the biomass allocations resulting from environmental gradients or plant growth. There is generally a tight balance between the amounts of biomass invested in different organs, which must be analyzed by means of an allometric model. The allometric exponent is not affected by individual growth and can reflect the changes in biomass allocation patterns of different parts. Therefore, the allometric exponent was chosen to study the relationship between biomass allocation pattern and herbivory tolerance. We selected four species (Wedelia chinensis, Wedelia trilobata, Merremia hederacea, and Mikania micrantha), two of which are invasive species and two of which are accompanying native species, and established three herbivory levels (0%, 25% and 50%) to compare differences in allometry. The biomass allocation in stems was negatively correlated with herbivory tolerance, while that in leaves was positively correlated with herbivory tolerance. Furthermore, the stability of the allometric exponent was related to tolerance, indicating that plants with the ability to maintain their biomass allocation patterns are more tolerant than those without this ability, and the tendency to allocate biomass to leaves rather than to stems or roots helps increase this tolerance. The allometric exponent was used to remove the effects of individual development on allocation pattern, allowing the relationship between biomass allocation and herbivory tolerance to be more accurately explored. This research used an allometric model to fit the nonlinear process of biomass partitioning during the growth and development of plants and provides a new understanding of the relationship between biomass allocation and herbivory tolerance.

A greater foraging scale, not a higher foraging precision, may facilitate invasion by exotic plants in nutrient-heterogeneous conditions.

Background and Aims: Soil nutrient heterogeneity has been proposed to influence competitive outcomes among different plant species. Thus, it is crucial to understand the effects of environmental heterogeneity on competition between exotic invasive and native species. However, the effects of soil nutrient heterogeneity on the competition between invasive and native plants have rarely been linked to root foraging behaviour. Methods: In this study, a competition experiment was performed with two invasive-native species pairs (BP-VC, Bidens pilosa vs. Vernonia cinerea; MM-PS, Mikania micrantha vs. Paederia scandens) grown under homogeneous and heterogeneous conditions in a common greenhouse environment. Root activity was assessed by determining the amount of strontium (Sr) taken up by the shoot of each species. Key Results: The invasive species exhibited a greater foraging scale, whereas the native species exhibited a higher foraging precision. A trade-off between foraging scale and precision was observed within each pair of invasive-native species. Compared with soil homogeneity, soil heterogeneity significantly increased the biomass of the two invasive species, B. pilosa and M. micrantha, under competitive conditions. Within each pair, the invasive species exhibited greater relative competitive ability with respect to shoot mass, and considerably more Sr taken up by the invasive species compared with the native species. The Sr acquisition results indicate that nutrient-poor conditions may facilitate the competitive ability of the native species V. cinerea, whereas M. micrantha may possess a stronger competitive ability regardless of soil nutrient conditions. Conclusion: Soil nutrient heterogeneity has the potential to promote the invasion of these two exotic species due to their larger foraging scale, stronger competitive ability and greater root activity relative to their counterpart native species. The present work highlights the importance of soil heterogeneity in plant invasion, particularly with regards to root foraging traits and competition between invasive and native plants.

Differential responses of invasive and native plants to warming with simulated changes in diurnal temperature ranges.

Although many studies have documented the effects of global warming on invasive plants, little is known about whether the effects of warming on plant invasion differ depending on the imposed change in different diurnal temperature ranges (DTR). We tested the impact of warming with DTR change on seed germination and seedling growth of eight species in the family Asteraceae. Four of these are invasive (Eupatorium catarium, Mikania micrantha, Biodens pilosa var. radiate, Ageratum conyzoides) in China, and four are native (Sonchus arvensis, Senecios candens, Pterocypsela indica, Eupatorium fortunei). Four temperature treatments were set in growth chambers (three warming by 3 °C with different DTRs and control), and experiments were run to mimic wintertime and summertime conditions. The control treatment (Tc ) was set to the mean temperature for the corresponding time of year, and the three warming treatments were symmetric (i.e. equal night-and-day) (DTRsym), asymmetric warming with increased (DTRinc) and decreased (DTRdec) DTR. The warming treatments did not affect seed germination of invasive species under any of the conditions, but DTRsym and DTRinc increased seed germination of natives relative to the control, suggesting that warming may not increase success of these invasive plant species via effects on seed germination of invasive plants relative to native plants. The invasive plants had higher biomass and greater stem allocation than the native ones under all of the warming treatments. Wintertime warming increased the biomass of the invasive and wintertime DTRsym and DTRinc increased that of the native plants, whereas summertime asymmetric warming decreased the biomass of the invasives but not the natives. Therefore, warming may not facilitate invasion of these invasive species due to the suppressive effects of summertime warming (particularly the asymmetric warming) on growth. Compared with DTRsym, DTRdec decreased the biomass of both the invasive and native plants, while the asymmetric summer warming treatments (DTRinc and DTRdec) decreased the biomass of the invasive but not the native plants. In addition, wintertime DTRinc did not enhance the biomass of all the plants relative to DTRsym. Our results were obtained in an unrealistic setting; the growth conditions in chambers (e.g. low light, low herbivory, no competition) are quite different from natural conditions (high light, normal herbivory and competition), which may influence the effects of warming on the seedling establishment and growth of both invasive and native plants. Nonetheless, our work highlights the importance of asymmetric warming, particularly in regards to the comparison with the effects of symmetric warming on both invasive and native plants. Conclusions regarding the effects of future warming should be made cautiously because warming with different DTRs may suggest different implications for invasion, and effects of warming may be different in different seasons.

The Invasion of Coastal Areas in South China by Ipomoea cairica May Be Accelerated by the Ecotype Being More Locally Adapted to Salt Stress.

Local adaptation and phenotypic plasticity are two alternative mechanisms used by invasive plants for range expansion. We conducted a series of experiments to investigate the role of these mechanisms in the recent expansion of the invasive Ipomoea cairica from non-saline to salt-stressed coastal habitats. A comparison of the plant's photosynthetic traits and construction costs across habitats was conducted through a field survey. Meanwhile, a full factorial greenhouse experiment was conducted with two ecotypes (non-saline and coastal) of I. cairica and two salinity gradients (water and 4 g L-1 NaCl solution) to evaluate the roles of the two strategies by comparing their main traits. The results revealed that the construction cost and Amax of I. cairica did not change with the habitat type. The ecotype and saline treatments, however, significantly influenced the plant growth. The non-saline ecotype (NE) generally showed higher or equal plasticity of biomass-allocation and functional traits compared to the coastal ecotype (CE). However, the fitness and biomass of the NE significantly decreased with salinity, whereas those aspects of the CE did not change. Our results indicate that the recent expansion of I. cairica into coastal areas may be accelerated by the local adaptation of the CE to salt stress. Additionally, in South China, the CE will most likely evolve adaptations to both saline and non-saline environments, which will further broaden the invasion range of I. cairica in the future.

Effects of climate change on plant population growth rate and community composition change.

The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades) based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR) and Barro Colorado Island, Panama (BCI)-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

A novel role of ethephon in controlling the noxious weed Ipomoea cairica (Linn.) Sweet.

Several auxin herbicides, such as 2, 4-D and dicamba, have been used to eradicate an exotic invasive weed Ipomoea cairica in subtropical China, but restraining the re-explosion of this weed is still a challenge. Since ethylene is one of the major intermediate functioning products during the eradication process, we explored the possibility, mechanism and efficiency of using ethephon which can release ethylene to control Ipomoea cairica. The results of the pot experiment showed that 7.2 g /L ethephon could totally kill Ipomoea cairica including the stems and roots. The water culture experiment indicated that ethephon released an abundance of ethylene directly in leaves and caused increases in electrolyte leakage, 1-aminocyclopropane-1-carboxylic acid (ACC), abscisic acid (ABA) and H2O2 and decreases in chlorophyll content and photosynthetic activity, finally leading to the death of Ipomoea cairica. The field experiment showed that the theoretical effective concentration of ethephon for controlling Ipomoea cairica (weed control efficacy, WCE = 98%) was 4.06 g/L and the half inhibitory concentration (I50) was 0.56 g/L. More than 50% of the accompanying species were insensitive to the phytotoxicity of ethephon. Therefore, ethephon is an excellent alternative herbicide for controlling Ipomoea cairica.

Biodiversity of Jinggangshan Mountain: the importance of topography and geographical location in supporting higher biodiversity.

Diversity is mainly determined by climate and environment. In addition, topography is a complex factor, and the relationship between topography and biodiversity is still poorly understood. To understand the role of topography, i.e., altitude and slope, in biodiversity, we selected Jinggangshan Mountain (JGM), an area with unique topography, as the study area. We surveyed plant and animal species richness of JGM and compared the biodiversity and the main geographic characteristics of JGM with the adjacent 4 mountains. Gleason's richness index was calculated to assess the diversity of species. In total, 2958 spermatophyte species, 418 bryophyte species, 355 pteridophyte species and 493 species of vertebrate animals were recorded in this survey. In general, the JGM biodiversity was higher than that of the adjacent mountains. Regarding topographic characteristics, 77% of JGM's area was in the mid-altitude region and approximately 40% of JGM's area was in the 10°-20° slope range, which may support more vegetation types in JGM area and make it a biodiversity hotspot. It should be noted that although the impact of topography on biodiversity was substantial, climate is still a more general factor driving the formation and maintenance of higher biodiversity. Topographic conditions can create microclimates, and both climatic and topographic conditions contribute to the formation of high biodiversity in JGM.

Non-Additive effects on decomposition from mixing litter of the invasive Mikania micrantha H.B.K. with native plants.

A common hypothesis to explain the effect of litter mixing is based on the difference in litter N content between mixed species. Although many studies have shown that litter of invasive non-native plants typically has higher N content than that of native plants in the communities they invade, there has been surprisingly little study of mixing effects during plant invasions. We address this question in south China where Mikania micrantha H.B.K., a non-native vine, with high litter N content, has invaded many forested ecosystems. We were specifically interested in whether this invader accelerated decomposition and how the strength of the litter mixing effect changes with the degree of invasion and over time during litter decomposition. Using litterbags, we evaluated the effect of mixing litter of M. micrantha with the litter of 7 native resident plants, at 3 ratios: M1 (1∶4, = exotic:native litter), M2 (1∶1) and M3 (4∶1, = exotic:native litter) over three incubation periods. We compared mixed litter with unmixed litter of the native species to identify if a non-additive effect of mixing litter existed. We found that there were positive significant non-additive effects of litter mixing on both mass loss and nutrient release. These effects changed with native species identity, mixture ratio and decay times. Overall the greatest accelerations of mixture decay and N release tended to be in the highest degree of invasion (mix ratio M3) and during the middle and final measured stages of decomposition. Contrary to expectations, the initial difference in litter N did not explain species differences in the effect of mixing but overall it appears that invasion by M. micrantha is accelerating the decomposition of native species litter. This effect on a fundamental ecosystem process could contribute to higher rates of nutrient turnover in invaded ecosystems.

High tolerance to salinity and herbivory stresses may explain the expansion of Ipomoea cairica to salt marshes.

BACKGROUND: Invasive plants are often confronted with heterogeneous environments and various stress factors during their secondary phase of invasion into more stressful habitats. A high tolerance to stress factors may allow exotics to successfully invade stressful environments. Ipomoea cairica, a vigorous invader in South China, has recently been expanding into salt marshes. METHODOLOGY/PRINCIPAL FINDINGS: To examine why this liana species is able to invade a stressful saline environment, we utilized I. cairica and 3 non-invasive species for a greenhouse experiment. The plants were subjected to three levels of salinity (i.e., watered with 0, 4 and 8 g L(-1) NaCl solutions) and simulated herbivory (0, 25 and 50% of the leaf area excised) treatments. The relative growth rate (RGR) of I. cairica was significantly higher than the RGR of non-invasive species under both stress treatments. The growth performance of I. cairica was not significantly affected by either stress factor, while that of the non-invasive species was significantly inhibited. The leaf condensed tannin content was generally lower in I. cairica than in the non-invasive I. triloba and Paederia foetida. Ipomoea cairica exhibited a relatively low resistance to herbivory, however, its tolerance to stress factors was significantly higher than either of the non-invasive species. CONCLUSIONS/SIGNIFICANCE: This is the first study examining the expansion of I. cairica to salt marshes in its introduced range. Our results suggest that the high tolerance of I. cairica to key stress factors (e.g., salinity and herbivory) contributes to its invasion into salt marshes. For I. cairica, a trade-off in resource reallocation may allow increased resources to be allocated to tolerance and growth. This may contribute to a secondary invasion into stressful habitats. Finally, we suggest that I. cairica could spread further and successfully occupy salt marshes, and countermeasures based on herbivory could be ineffective for controlling this invasion.

Responses of Mikania micrantha, an invasive weed to elevated CO2: induction of ß-caryophyllene synthase, changes in emission capability and allelopathic potential of ß-caryophyllene.

To better understand the effect of predicted elevated levels of carbon dioxide (CO2) on an invasive weed Mikania micrantha, we constructed a suppressive subtractive hybridization (SSH) library from the leaves of M. micrantha exposed to CO2 at 350 and 750 ppm for 6 d, and isolated a novel gene named ß-caryophyllene synthase. ß-Caryophyllene synthase catalyses the conversion of farnesyl diphosphate to ß-caryophyllene, a volatile sesquiterpene with allelopathic potential. Real-time PCR analysis revealed that gene expression of ß-caryophyllene synthase in M. micrantha leaves was strongly induced in response to elevated CO2. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography (GC) analyses showed that emission levels of ß-caryophyllene from leaves of M. micrantha increased when exposed to 750 ppm CO2. Bioassays showed that phytotoxicity of ß-caryophyllene against Raphanus sativus, Brassica campestris, Lactuca sativa, and M. micrantha was dose-dependent and varied with the receptor plants and concentrations of CO2. ß-Caryophyllene displayed higher phytotoxic effects at 750 ppm than those at 350 ppm CO2, especially on R. sativus. These results suggest that elevated atmospheric CO2 levels may enhance biosynthesis and phytotoxicity of allelochemicals in M. micrantha, one of the worst invasive weeds in the world, which in turn might enhance its potential allelopathic effect on neighboring native plants if released in bioactive concentrations. Further investigations are required to determine the adaptive responses of both invasive and native plants to a gradual increase of atmospheric CO2 to 750 ppm predicted over a 100 year period.

Identification of genes differentially expressed in Mikania micrantha during Cuscuta campestris infection by suppression subtractive hybridization.

The influence of Cuscuta campestris on its host Mikania micrantha has been studied with respect to biomass accumulation, physiology and ecology. Molecular events of this parasitic plant-plant interaction are poorly understood, however. In this study, we identified novel genes from M. micrantha induced by C. campestris infection. Genes expressed upon parasitization by C. campestris at early post-penetration stages were investigated by construction and characterization of subtracted cDNA libraries from shoots and stems of M. micrantha. Three hundred and three presumably up-regulated expressed sequence tags (ESTs) were identified and classified in functional categories, such as "metabolism", "cell defence and stress", "transcription factor", "signal transduction", "transportation" and "photosynthesis". In shoots and stems of infected M. micrantha, genes associated with defence responses and cell wall modifications were induced, confirming similar data from other parasitic plant-plant interactions. However, gene expression profiles in infected shoots and stems were found to be different. Compared to infected shoots, more genes induced in response to biotic and abiotic stress factors were identified in infected stems. Furthermore, database comparisons revealed a notable number of M. micrantha ESTs that matched genes with unknown function. Expression analysis by quantitative real-time RT-PCR of 21 genes (from different functional categories) showed significantly increased levels for 13 transcripts in response to C. campestris infection. In conclusion, this study provides an overview of genes from parasitized M. micrantha at early post-penetration stages. The acquired data form the basis for a molecular understanding of host reactions in response to parasitic plants.

Genome sequence and characterization of a new virus infecting Mikania micrantha H.B.K.

The complete RNA genomic sequence of a new virus infecting Mikania micrantha, designated as Mikania micrantha wilt virus (MMWV), has been determined. The genomic sequence and the predicted gene products of MMWV were similar to those of the other viruses of the genus Fabavirus. The MMWV nucleotide sequence showed 75.6% identity to that of gentian mosaic virus, 56.6 and 57% identity to those of two Broad bean wilt virus 1 isolates, and between 55.7 and 58% identity to those of seven Broad bean wilt virus 2 isolates. Our results suggested that MMWV represents a distinct isolate of the candidate species Gentian mosaic virus.

[Differences in urbanization process of catchments in dongjiang watershed and their effects on landscape pattern].

Based on 1991, 1998, and 2006 TM images, the areas of different land use types and the landscape indices of three catchments (catchment a, b, and c, which represented upper, middle, and lower reaches, respectively) in Dongjiang watershed were analyzed, aimed to study the differences in urbanization process along Dongjiang River, and their effects on landscape pattern. The results showed that the degree and speed of urbanization increased from the upper to the lower reach of Dongjiang River. Urbanization had significantly effects on water and vegetation. Urban land area was positively correlated with water body area, and negatively correlated with forest land area. However, to some extent, urbanization stepped into a relatively high degree might benefit forest recovery. The landscape pattern of catchments a and b kept complicating from 1991 to 2006, while that of catchment c was getting complex from 1991 to 1998 and then becoming simple from 1998 to 2006, indicating that with the development of urbanization, landscape pattern presented a "simple-complex-simple" tendency. Understanding the change patterns of the landscape pattern along Dongjiang River would benefit the management and sustainable development of the watershed as a whole.

Evaluation of ambient air quality in Guangzhou, China.

On the basis of the reported air quality index (API) and air pollutant monitoring data provided by the Guangzhou Environment Monitoring Stations over the last twenty-five years, the characteristics of air quality, prominent pollutants, and variation of the average annual concentrations of SO2, NO2, total suspended particulate (TSP), fine particulates (PM10), CO and dustfall in Guangzhou City were analyzed. Results showed that TSP was the prominent pollutant in the ambient air environment of Guangzhou City. Of the prominent pollutants, TSP accounted for nearly 62%, SO2 12.3%, and NOx 6.4%, respectively. The average API of Guangzhou over 6 years was higher than that of Beijing, Tianjin, Nanjing, Hangzhou, Suzhou and Shanghai, and lower than that of Shenzhen, Zhuhai and Shantou. Concentrations of air pollutants have shown a downward trend in recent years, but they are generally worse than ambient air quality standards for USA, Hong Kong and EU. SO2 and NOx pollution were still serious, impling that waste gas pollution from all kinds of vehicles had become a significant problem for environmental protection in Guangzhou. The possible causes of worsening air quality were also discussed in this paper.

[Age estimation and age structure of Cycas fairylakea population in Shenzhen City].

Based on the structural characteristics of Cycas trunk, including vegetative leaf base scars, sporophyll concave rings, and average occurrence probabilities of vegetative leaf and sporophyll, a method for the age estimation of Cycas fairylakea population was developed, and the age of each individual was calculated. Three approaches, i.e., age structure diagram, age distribution curve and curve estimation were used to study the age structure of C. fairylakea population at genet and clone population levels. The age structure diagram showed that the clone population of C. fairylakea was stable, but the genet population was in declining. However, both of the clone and genet populations were in declining when using the other two approaches. It was considered that the C. fairylakea population was in declining, and needed an urgent protection.

Roots of pioneer trees in the lower sub-tropical area of Dinghushan, Guangdong, China.

Representative pioneer tree root systems in the subtropical area of South China were examined with regard to their structure, underground stratification and biomass distribution. Excavation of skeleton roots and observation of fine roots of seven species including the Euphorbiaceae, Theaceae, Melastomataceae, Lauraceae and Fagaceae families was carried out. The results showed that: (1) Pioneer tree roots in the first stage of natural succession were of two types, one characterized by taproot system with bulky plagiotropic branches; the other characterized by flat root system with several tabular roots. The late mesophilous tree roots were characterized by one obvious taproot and tactic braches roots up and down. Shrub species roots were characterized by heart fibrous root type featured both by horizontally and transversally growing branches. Root shapes varied in different dominant species at different stages of succession. (2) Roots of the different species varied in the external features-color, periderm and structure of freshly cut slash. (3) In a set of successional stages the biomass of tree roots increased linearly with the age of growth. During monsoon, the total root biomass amounted to 115.70 t/ha in the evergreen broad-leaved forest; 50.61 t/ha in needle and broad-leaved mixed forest dominated by coniferous forest; and 64.20 t/ha in broad-and needle-leaved mixed forest dominated by broad-leaved heliophytes, and are comparable to the underground biomass observed in similar tropical forests. This is the first report about roots characteristics of forest in the lower sub-tropical area of Dinghushan, Guangdong, China.

[Studies on the adaptation of five legumes species to copper tailings].

Pot experiments with five legumes were conducted in five different amendment substrates for the reclamation of copper tailings in Tongling, Anhui province. The five tested legumes species are Glycine max, Phaseolus angularis, P. calcaratus, P. radiatus, P. mininus. The results showed that the main factors to restrict growing of the vegetation are poor nutrient and high concentration of Cu. The seeds of the legumes species could germinate, but they germinated later in the substrates with higher proportion of copper tailings than in the substrates with lower proportion of copper tailings. After clipping, G. max, P. angularis, P. calcaratus, P. radiatus were alive all the time, but some of the other two legumes species were dead because of the their non-adaptation to the copper tailings. At the same amendment group, the chlorophyll contents of G. max and P. calcaratus were higher than that of other three experimental species on the 50th day. The height and the biomass of G. max and P. calcaratus were higher than that of other three experimental species on the 70th day too. According to the biological characteristics of the five species during the growth periods about indexes of the seeding survival, chlorophyll content, height and biomass, G. max and P. calcaratus are more adaptive and tolerant than the other legumes and the TA75 amendment approach is the more reasonable for the reclamation of copper tailings.

Environmental effect of vegetation restoration on degraded ecosystem in low subtropical China.

The environmental effect of degraded ecosystem's vegetation restoration in low subtropical China was studied. Results indicated that the vegetation recovery on degraded lands significantly ameliorates surrounding environment, increases species diversity, improves soil structure, raises soil fertility, enhances productivity, and promotes regional agricultural production and social economic development dramatically. Through the combining engineering and biological measures, the restoration of degraded ecosystem in low subtropical area is possible and economical. The restoration experience in Xiaoliang, Wuhua and other sites are valuable for other degraded subtropical area was introduced.

New emergy indices for sustainable development.

The emergy indices for the evaluation of system's sustainable development ability were studied. Results indicated that the emergy indices are simplified and merged, and a new emergy index for sustainable development (EISD) is deduced. Employing EISD, two cases are conducted. The first one is to compare three different dike-pond agro-ecological engineering modes, which are: melon-melon-cabbage-four domestic fishes (mode I), melon-melon-cabbage-pig-four domestic fishes (mode II) and melon-melon-cabbage-pig-four domestic fishes combined with Siniperca chuatsi B. (mode III). The result is that the EISD of mode I is 0.53. Mode II's EISD is 5.26 times of mode I, and mode III's EISD is 6.83 times of mode I. The second one is to evaluate the development of Zhongshan City, Pearl Delta, during 1996 to 2000. The result indicated that the EISD of Zhongshan had appreciably declined from 1996 to 1998, and quickly improved from 1998 to 2000, partly because of its environment protection and product construction. Both of the two cases studies showed that EISD can assessment the sustainable development ability more roundly, with the consideration of environmental impact and social-economic effect at the same time.