Influence of edaphic factors on the structure and distribution of plant species in and around Mekeiman Marsh Wetland, Northeast of Algeria

Touarfia M, Bouali N, Djouamaa Ak, Maazi MC, Houhamdi M. 2021. Influence of edaphic factors on the structure and distribution of plant species in and around Mekeiman Marsh Wetland, Northeast of Algeria. Biodiversitas 22: 3219-3228. Understanding the environmental factors that influence plant species composition and distribution is essential for successful management of biodiversity. Hence, the purpose of the present study was to assess plant species composition and distribution in a freshwater wetland Mekeiman Marsh, Northeastern Algeria and to analyze the influence of environmental factors on local plant species. To explore the distribution of plant species in this Marsh and analyze their associations with edaphic soil factors, the mapping and types of plant species in this area were analyzed by MapInfo and principal component analysis (PCA) ordination. For this purpose, four stations were chosen according to a stratified sampling method and phytosociological surveys were carried out in 12 plots, which were sampled using the Braun- Blanquet method. Multivariate analyses were used to determine the relationship between plant species distribution and edaphic factors. The R i386 (version 4.0.3) software was used for data analysis. We have identified 48 plant species belonging to 21 families. Results of biological types in the study area revealed the dominance of hemicryptophytes and therophytes, which indicates the presence of therophytization in this Marsh. Spatial distribution maps showed that plant species were divided into two categories viz. sparse and scattered plants according to the humidity gradient. The most important edaphic factors associated with plant species in Mekeiman Marsh were Sodium, Phosphorus, active limestone, Magnesium, clay, organic matter, C/N and Azot. By combining mapping and influence of edaphic factors on the structure and distribution of plant species in this wetland, it was known that the plant assemblages of this Marsh make disproportionately important contributions to wetland-level diversity. By combining mapping and influence of edaphic factors on the structure and distribution of plant species in this wetland, the plant assemblages of this Marsh make disproportionately important contributions to wetland-level diversity.

Geological methane emissions and wildfire risk in the degraded permafrost area of the Xiao Xing’an Mountains, China

With global warming, the carbon pool in the degradation zone of permafrost around the Arctic will gradually be disturbed and may enter the atmosphere in the form of released methane gas, becoming an important factor of environmental change in permafrost areas. We selected the northwestern section of the Xiao Xing'an Mountains in China as the study area, located in the degradation zone on the southern margin of the permafrost region in Eurasia, and set up multiple study monitoring areas equipped with methane concentration sensors, air temperature sensors, pore water pressure sensors and soil temperature sensors for long-term monitoring of data changes using the high-density electrical method, ground penetrating radar and on-site drilling to survey the distribution of frozen soil and geological conditions in the study area, combined with remote sensing images of Sentinel-2 L1C and unmanned aerial vehicle photographs and three-dimensional image reconstruction, analysis of fire activities and related geological environmental factors. The results show that since 2004, the permafrost thickness of the marsh wetland in the study area has gradually reduced and the degradation rate obviously accelerated; the organic matter and methane hydrate (metastable methane hydrate and stable methane hydrate) stored in the permafrost under the marsh wetland are gradually entering the atmosphere in the form of methane gas. Methane emissions show seasonal changes, and the annual methane emissions can be divided into three main stages, including a high-concentration short-term emission stage (March to May), a higher-concentration long-term stable emission stage (June to August) and a higher-concentration short-term emission stage (September to November); there is a certain correlation between the change in atmospheric methane concentration and the change in atmospheric pressure and pore water pressure. From March to May every year (high-concentration short-term emission stage), with snow melting, the air humidity reaches an annual low value, and the surface methane concentration reaches an annual high value. The high concentration of methane gas entering the surface in this stage is expected to increase the risk of wildfire in the permafrost degradation area in two ways (increasing the regional air temperature and self-combustion), which may be an important factor that leads to a seasonal wildfire frequency difference in the permafrost zone of Northeast China and Southeast Siberia, with the peak in spring and autumn and the monthly maximum in spring. The increase in the frequency of wildfires is projected to further generate positive feedback on climate change by affecting soil microorganisms and soil structure. Southeastern Siberia and northeastern China, which are on the southern boundary of the permafrost region of Eurasia, need to be targeted to establish fire warning and management mechanisms to effectively reduce the risk of wildfires.

Study of marsh wetland landscape pattern evolution on the Zoigê Plateau due to natural/human dual-effects

Zoigê Plateau, China’s largest plateau marsh wetland, has experienced large-scale degradation of the marsh wetland and evolution of the wetland landscape pattern over the past 40 years due to climate warming and human activities. How exactly do the wetland landscape pattern characteristics change? How do climatic change and human activities affect the wetland evolution? These questions are yet to be systematically investigated. In order to investigate changes to the marsh wetland on the Zoigê Plateau, field investigations, spatial and statistical analysis were undertaken. Findings from our study indicate that from 1977–2016, the area of marsh wetland on the Plateau reduced by 56.54%, approximately 66,700 hm2 of marsh wetland has been lost. The centroids of both marsh and marshy meadow migrated and the landscape centroid migration behaviors were also correlated with the distribution and variation of the marsh wetland on different slopes. In addition, the number of marsh landscape patches initially increased before decreasing; the number of marshy meadow landscape patches also recorded an initial increase, followed by a decline before a final increase. As the effects of human activities weakened, the aggregation degrees of both marsh and marshy meadow increased. Overall, the fragmentation degree, diversity and fractal dimension of the marsh wetland all declined. An investigation into the driving factors affecting the Plateau area shows that the increase of annual average temperature was the natural factor while trenching and overgrazing were the main human factors resulting in wetland degradation. Results from this study provide basic data and theoretical foundation for the protection and restoration of marsh wetland in alpine regions.