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Farming plot reconstruction engineering is important in mitigating cultivated land fragmentation and promoting intensified production in hilly mountainous regions. As an anthropogenic disturbance, farming plot reconstruction and subsequent agricultural intensification have considerable effects on cultivated land, ecological environments, and pedogenesis. Although researchers have given considerable attention to changes in the physical and nutrient properties of soil in reconstructed farming plots, the connection between soil engineering and anthropogenic pedogenesis is often neglected. In this paper, we compared samples obtained during farming plot reconstruction engineering and agricultural intensification in terms of different soil properties. The results indicated that reconstruction changed the soil profile patterns from A–C to A–B–C, thereby significantly increasing the soil thickness, bulk density, clay content, pH, soil organic carbon, total nitrogen, C/N ratio, and cation exchange capacity. The geochemical composition notably varied in topsoil; the chemical index of alteration (CIA) and the chemical index of weathering (CIW) decreased markedly, and the Na 2 O/K 2 O ratio (Na/K) increased slightly. After a period of agricultural intensification, the physical and chemical properties of soil improved gradually with a high coefficient of variation. However, the soil exhibited Mg and Ca leaching and K and Na accumulation, and the intensity of chemical weathering was not significantly stronger with higher CIA values, higher CIW values, and lower Na/K ratios. These changes indicated that the anthropogenic disturbances from soil engineering accelerated the physical weathering and uniformity of purple soil but depressed soil chemical weathering to some extent. The anthropogenic disturbances of agricultural intensification disrupted the homogeneity of soils but did not significantly promoted the physical and chemical weathering of purple soil. This study provides guidelines for rational soil usage in reconstructed farming plots and may aid in soil classification. • Soil engineering accelerates physical weathering but destroys chemical weathering. • Agricultural intensification has positive impacts on soil quality. • Anthropogenic disturbances create a problem for soil classification. [ABSTRACT FROM AUTHOR]

The Assif n’Imserdane valley, located in the Jebel Toubkal area of the High Atlas, Morocco, is a highly dynamic geomorphological setting. The valley was glaciated during the Late Pleistocene, and subsequently experienced a catastrophic rock avalanche leading to the formation of one of the largest mass movement landforms in North Africa. Recent research (Hughes et al., GSA Bulletin 126: 1093–1104) has dated the formation of the rock avalanche to the mid-Holocene at 4.5 ± 0.5 ka. In this paper, we examine the sedimentological (organic matter content, magnetic susceptibility, particle size and XRF) and palaeoecological (pollen and spores, non-pollen palynomorphs (NPPs), microcharcoal and conifer tracheid fragments) record of a small infilled basin located adjacent to a Late Pleistocene moraine and close to the rock avalanche in the Arroumd sector. The deposits, primarily fine-grained and minerogenic with a low concentration of organic microfossils including pollen, coprophilous ascospores, wood and charcoal microfragments, are enriched in fine silts and ferrimagnetic minerals, consistent with erosional sources from surrounding slope soils. Three radiocarbon dates from the deposit indicate that the infill event occurred during the first millennium AD (after 430–640 AD). As such, the deposits point to a phase of slope instability and erosion that is not linked to either deglaciation processes or to the mid-Holocene rock avalanche. Instead, the nature and timing suggest that an anthropogenic trigger of degradation to the natural vegetation cover may be implicated, consistent with an increasing scale and intensity of pastoral activity in the southern High Atlas during the early Islamic period in Morocco. The record casts light on a previously undocumented phase of landscape instability in the dynamic setting of the Assif n’Imserdane valley, and highlights the potential for further exploration of small infilled basins in the High Atlas to illuminate the geoecological history of the region. [ABSTRACT FROM AUTHOR]

This paper studies the changes in the geomorphological dynamics recorded in 18 ephemeral streams located on the east side of Loma Pelada (Tafi Valley), a part of the Sierras Subandinas (Northwest Argentina). The applied methodology is based on photointerpretation, field survey, and descriptions of the Holocene alluvial fillings dated by tephras, archaeological artefacts, and absolute datings. The records show a coupled system of slope-terrace-alluvial fans resulting from the environmental changes of four alternating aggradation/degradation stages. The oldest stage (1) was generated by climatic causes and covers Early to Mid-Holocene ( ca. 13,000–10,000 BP to ca. 4200 BP). After the incision of these accumulations, a new aggradation stage (2) was triggered by anthropogenic activity occurring from right before 2500 BP to the 15th century. During that time human occupations of the Tafí Valley were intense. Two wetter events occurred around 4200 and 2800 BP in the area, related to global cooling phases. Lastly, two more recent phases (3 and 4) are associated with the climatic variability of the LIA and the Present Warm Period. The results highlight the sensitivity of headwater catchments of dry subtropical mountainous areas to climate changes, anthropogenic impact, and their relationship with global climatic data. [ABSTRACT FROM AUTHOR]

The farming-pastoral region of North China is a region that has suffered from serious desertification, and the multiple transitional characteristics in this region make it very difficult to link the progress of desertification to the driving forces behind it. This paper mainly focuses on the dynamics of desertification over the past 10 years and their relationship to climate change and human activity. According to the MODIS images in 2000 and 2010, the farming-pastoral region had experienced significant desertification dynamics over the past 10 years. The area of regions that had undergone desertification reversion and expansion were 186,240 km 2 and 199,525 km 2 respectively, and the spatial distribution of these regions showed great heterogeneity. The relationship between desertification dynamics and their driving forces was investigated by comparing the change in the NPP that was induced by climate change and human activity for each pixel that experienced desertification reversion and expansion. From 2000 to 2010, the coupling of climate change and human activity was the dominant factor behind desertification reversion. However, the human activity was the dominant factor that controlled the desertification expansion process between 2000 and 2010. The driving processes of desertification also had considerable spatial heterogeneity, and the dominant factors behind desertification reversion and expansion in each sub-region were not completely the same. So, the scale effect must be considered when explaining the results from similar studies. [ABSTRACT FROM AUTHOR]