The Synergism between Methanogens and Methanotrophs and the Nature of their Contributions to the Seasonal Variation of Methane Fluxes in a Wetland:The Case of Dajiuhu Subalpine Peatland

Wetland ecosystems are the most important natural methane(CH_(4))sources,whose fluxes periodically fluctuate.Methanogens(methane producers)and methanotrophs(methane consumers)are considered key factors affecting CH_(4)fluxes in wetlands.However,the symbiotic relationship between methanogens and methanotrophs remains unclear.To help close this research gap,we collected and analyzed samples from four soil depths in the Dajiuhu subalpine peatland in January,April,July,and October 2019 and acquired seasonal methane flux data from an eddy covariance(EC)system,and investigated relationships.A phylogenetic molecular ecological networks(pMENs)analysis was used to identify keystone species and the seasonal variations of the co-occurrence patterns of methanogenic and methanotrophic communities.The results indicate that the seasonal variations of the interactions between methanogenic and methanotrophic communities contributed to CH_(4)emissions in wetlands.The keystone species discerned by the network analysis also showed their importance in mediating CH_(4)fluxes.Methane(CH_(4))emissions in wetlands were lowest in spring;during this period,the most complex interactions between microbes were observed,with intense competition among methanogens while methanotrophs demonstrated better cooperation.Reverse patterns manifested themselves in summer when the highest CH_(4)flux was observed.Methanoregula formicica was negatively correlated with CH_(4)fluxes and occupied the largest ecological niches in the spring network.In contrast,both Methanocella arvoryzae and Methylocystaceae demonstrated positive correlations with CH_(4)fluxes and were better adapted to the microbial community in the summer.In addition,soil temperature and nitrogen were regarded as significant environmental factors to CH_(4)fluxes.This study was successful in explaining the seasonal patterns and microbial driving mechanisms of CH_(4)emissions in wetlands.

Predation Capability of Black Kite (Milvus migrans parasitus) on Locust as a Biological Control Option in Madagascar

In Madagascar, the South and Southwest regions have for decades had locust outbreaks that have devastated crop fields. The locust species dominant in this area are the red locust (Nomadacris septemfasciata) and the Migratory Locust (Locusta migratoria capito). This paper aimed at determining the predation values from the Black Kite (Milvus migrans parasitus), a natural enemy for locusts, as a biological measure for locust outbreak control. Two types of experiments were done that included observed predation and experimental predation. It was observed, in the observed predation, that a higher number of locusts were found in the bird’s stomach during the afternoon session (mean = 66) than during the morning session (mean = 21). The high peak observed during the afternoon session was also associated with the feeding of larvae of the migratory locust. The experimental predation results showed that almost 100 percent of the larval and 97 percent of the fledglings were fed on. The experimental predation results also showed that there was no preference for larvae or fledglings in the cage and that the bird fed on the different combinations equally. This study showed that the Black Kite birds can effectively control locust population in an outbreak when they are easy to predate on. However, there is a need to assess the population of birds in locust infested areas to determine if the bird population is enough to predate on a locust outbreak.

Net Ecosystem CO2 Flux and Effect Factors in Peatland Ecosystem of Central China

Peatland ecosystems play an important role in the global carbon cycle because they act as a pool or sink for the carbon cycle. However, the relationship between seasonality effect factors and net ecosystem CO2 exchange (NEE) remains to be clarified, particularly for the non-growing season. Here, based on the eddy covariance technique, NEE in the peatland ecosystem of Central China was examined to measure two years’ (2016 and 2017) accumulation of carbon dioxide emissions with contrasting seasonal distribution of environmental factors. Our results demonstrate the cumulative net ecosystem CO2 emissions during the study period was in the first non-growing season 2.94 ± 4.83 μmolCO2 m-2.s-1 with the lowest values in the same year in first growing season was -2.79 ± 4.92 μmolCO2 m-2.s-1. The results indicate the effect of seasonal variations of NEE can be directly reflected in daily and seasonal variations in growth and respiration of peatland ecosystem by environmental parameters over different growing stages.

Assessment of soil degradation and chemical compositions in Rwandan tea-growing areas

This study has focused on the processes of soil degradation and chemical element concentration in tea-growing regions of Rwanda,Africa.Soil degradation accelerated by erosion is caused not only by topography but also by human activities.This soil degradation involves both the physical loss and reduction in the amount of topsoil associated with nutrient decline.Soil samples were collected from eleven tropical zones in Rwanda and from variable depth within each collecting site.Of these,Samples from three locations in each zone were analyzed in the laboratory,with the result that the pH of all soil samples is shown to be less than 5（pH〈5） with a general average of 4.4.The elements such as iron（Fe）, copper（Cu）,manganese（Mn）,and zinc（Zn） are present in high concentration levels.In contrast calcium （Ca） and sodium（Na） are present at low-level concentrations and carbon（C） was found in minimal concentrations.In addition,elements derived from fertilizers,such as nitrogen（N）,phosphorous（P）,and potassium（K） which is also from minerals such as feldspar,are also present in low-level concentrations. The results indicate that the soil in certain Rwandan tea plantations is acidic and that this level of pH may help explain,in addition to natural factors,the deficiency of some elements such as Ca,Mg,P and N.The use of chemical fertilizers,land use system and the location of fields relative to household plots are also considered to help explain why tea plantation soils are typically degraded.

Statistical Analysis of Climatic Data:Case of Temperature and Rainfall

Climate is a general weather condition in the air above the Earth such as wind,temperature,humidity, rain...especially at a particular time over a particular area.It is said that there is interdependence between those elements.In order to check out this connectivity, a statistical analysis between rainfall and temperature was carried out by analyzing the correlation and linear regression as well as testing the

Vegetation types and climate conditions reflected by the modern phytolith assemblages in the subalpine Dalaoling Forest Reserve, central China

This research describes modern phytolith records and distributions from subalpine surface soils in the Dalaoling Forest Reserve, and reveals its implications for local climate conditions with respect to the altitude gradient. Well-preserved phytolith morpho-types, assem- blages, and climatic indices were used to study the relationship between local vegetation and climate condi- tions. The phytolith classification system is mainly based on the characteristics of detailed morpho-types described for anatomical terms, which are divided into seven groups： long cells, short cells, bulliform cells, hair cells, pterido- phyte type, broad-leaved type, and gymnosperm type. Phytoliths originating from the Poaceae are composed of Pooideae （rondel and trapeziform）, Panicoideae （bilobate, cross, and polylobate）, Chloridoideae （short/square sad- dle）, and Bambusoideae （oblong concave saddle）. Based on the altitudinal distribution of the phytolith assemblages and the indices of aridity （Iph）, climate （Ic）, and tree cover density （D/P）, five phytolith assemblage zones have revealed the five types of climatic conditions ranging from 1,169 m to 2,005 m in turn： warm-wet, warm-xeric to warm-mesic, warm- xeric to cool-mesic, cool-xeric, and cool-mesic to cool-xeric. The Bambusoideae, Panicoideae, and Chloridoideae are the dominant vegetation at the lower-middle of the mountains, while Pooideae is mainly distributed in the higher mountains. The close relationship between phytolith assembleages and changes of altitude gradient suggest that vegetation distribution patterns and plant ecology in the Dalaoling mountains are controlled by temperature and humidity conditions. Our results highlight the importance ofphytolith records as reliable ecoclimatic indicators for vegetation ecology in subtropical regions.