Drivers of the Distribution of Soil Organic Carbon Stocks in the Topsoil Under Pinus Hartwegii Lindl. Forest, Along an Elevation Gradient in Central Mexico

Background: Mountain forest soils (≥2,500 m a.s.l.[1]), where elevation is crucial in the ecosystem dynamic, have a great capacity to capture and preserve carbon for a long time. The aim of this research was to determine the role of elevation combined with soil, climate, and vegetation variables on soil organic carbon (SOC) stocks distribution under P. hartwegii in the Nevado de Toluca Volcano, a protected area in Mexico. Topsoil samples (0-15 cm depth) collected every 100 m in elevation (3,400-4,000 m) were chemically and physically examined in statistical analysis together with vegetation structure and climate variables. Derived from field forest conditions, elevation plots were additional analyzed as logged (3,400-3,800 m) vs no-logged (3,900-4,000 m). Results: SOC stocks followed a significant linear trend (r2= 0.70; p= 0.02) along the elevation gradient, being highest at 4,000 m (173.1 ± 5.2 Mg C ha-1) and lowest at 3,700 m (146.8 Mg C ha-1). Multiple regression analyses showed that SOM, BD, and mean annual temperature (MAT) were the main abiotic drivers of SOC stocks variability (94.5 %) along the elevation gradient. Meanwhile, from the logistic multiple regression, higher tree shrubs and herbs density, in addition to lower tree height and grass cover at lower elevations, indicate a significant effect of logging on soil traits and vegetation structure, depending on the elevation plot. Conclusions: This research evaluated the SOC stocks and the potential effect of current warming over mountain soils, using the elevation as a proxy for both environmental and human drivers of SOC stocks in mountain forest ecosystems. Higher SOM and grass cover, larger-diameter trees together with low temperatures and logging restrictions in the high elevation range suggest a slower decomposition rate and SOC long-term stability. Despite the fact that we do not know about the intensity and cutting cycle, nor the size of the clearings derived from the trees removed, results from this research show how logging could exacerbate these effects and diminish SOC stocks, as well as the capacity of mountain soils to mitigate the effects of climate change.

Three new enchytraeid species (Enchytraeidae, Annelida) from mountain soils of Korea and ten species new for the country

In this paper, three new enchytraeid species (Enchytraeidae, Clitellata) are described from different mountains of Korea: Cognettia koreana sp. n., Henlea bidiverticulata sp. n. and Mesenchytraeus longidiverticulatus sp. n. Validity of these new species was confirmed by comparative morphological and molecular taxonomic analyses (based on ITS, CO1 and H3 sequences). In addition, ten enchytraeid species never recorded before from Korea were found in the studied soil samples: Bryodrilus diverticulatus Černosvitov, 1929, Cernosvitoviella atrata Bretscher, 1903, Cernosvitoviella minor Dózsa-Farkas, 1990, Cognettia lapponica Nurminen, 1965, Cognettia varisetosa (Martinsson, Rota & Erséus, 2015), Fridericia cf. sohlenii Rota, Healy & Erséus, 1998, Henlea nasuta Eisen, 1878, Marionina clavata Nielsen & Christensen, 1961, Marionina communis Nielsen & Christensen, 1959, Marionina seminuda Xie & Rota, 2001. Morphological observations and new reference DNA sequences are also provided for the above-mentioned species.

The Growth Promotion of Peppers (Capsicum annuum L.) by Trichoderma guizhouense NJAU4742-Based Biological Organic Fertilizer: Possible Role of Increasing Nutrient Availabilities

Trichoderma spp. is a cosmopolitan group of soil fungi which plays a remarkable role in stimulating plant growth after interacting with plant roots and has good application prospects in intensive agriculture. In this study, rice straw and amino acids improved the population of Trichoderma guizhouense NJAU4742 under solid-state fermentation and helped us develop a new type of organic fertilizer. The effects of this biological organic fertilizer were evaluated in the growth of peppers (Capsicum annuum L.) for two seasons under sandy and mountain soils. In the first season, the yields in T6 (0.06% solid fermentation products in soil) and AT6 (added 0.06% solid fermentation products and 1% amino acid organic fertilizer in soil) treatments were increased by 41.8% and 52.3% in sandy soil and by 51.6% and 46.5% in mountain soil, respectively, compared with chemical fertilizer. During the second season, the same trend was obtained in both sandy and mountain soils. Soil peroxidase activity (125.2 μmol·g−1 dw), urease activity (58.7 μmol·g−1 dw) and invertase activity (13.11 mg·g−1 dw) reached their highest levels in biological organic fertilizer compared to the treatments with chemical fertilizer and solid fermentation products. Redundancy analysis showed that crop yield was positively correlated with enzyme activities, soil organic carbon, total nitrogen, and available phosphorus. Thus, we demonstrated that NJAU4742-enriched biological organic fertilizer could accelerate the transformation of nutrients and promote pepper growth.