Afforestation is a widely accepted measure to control soil erosion around the world. A large area of forest has been built to prevent slope soil erosion in the red soil region of southern China since the 1980s. The vegetation coverage has significantly increased; however, there is still moderate or severe soil erosion under the forest. In order to improve the situation, it is necessary to study the effects of canopy on soil erosion under the forest. Standard runoff plots were established on two typical sites, which represented pure Pinus massoniana Lamb. forest and bare land, respectively. Precipitation redistribution and throughfall indices including raindrop size, raindrop velocity, and the kinetic energy (KE) of raindrops were quantified. The results showed that 29.3% of the precipitation was directly prevented from reaching the forest land surface. The canopy interception effect was better under low rainfall intensity than high rainfall intensity. Compared with open rainfall, throughfall raindrops were 16.3% fewer in number, larger in size, and the range of throughfall drop size distribution (DSD) was enlarged. The volume ratio of large drops was larger with higher rainfall intensity. When the rainfall intensity was less than 14 mm h⁻¹, throughfall kinetic energy (TKE) was higher than open rainfall kinetic energy (OKE) owing to the higher volume ratio of large raindrops. When the rainfall intensity was more than 14 mm h⁻¹, TKE was smaller owing to the large raindrops failing to reach their final velocities: their mean velocity was 80% of their final velocity. The sediment yield was the largest under high rainfall intensity and the effect of sediment reduction was the largest under moderate rainfall intensity. Therefore, the largest KE did not lead to the maximum sediment yield; canopy interception was also an important factor affecting sediment yield.

Vegetation plays a significant role in controlling soil erosion. However, the effects of each vegetation type on soil erosion have not been fully investigated. In order to explore the influence of multiple vegetation covers on soil erosion and surface runoff generation, 10 different vegetation types, typical of the Nverzhai small basin, have been selected for this study. Regional precipitation, surface runoff, and sediment yield were measured from 2007 to 2018. The wettest year recorded was 2012. Recorded data confirmed that July was the wettest month in this region while January and December were the driest months. Furthermore, surface runoff and sediment yield associated with different vegetation types gradually decreased after 2013, which is the quantification of the consequences due to afforestation processes started in this area. Surface runoff and sediment content recorded for the configuration of sloping farmland were the largest between the different investigated vegetation types. The smallest were the broad-leaved mixed forest, the coniferous mixed forest, and shrubs. Finally, a significant linear positive correlation was found between rainfall and surface runoff, as well as sediment yield (R² = 0.75). This suggests that climate change implications could be limited by using the more efficient vegetation covering. This research indicates that the ground cover is a key element in controlling soil and water loss, as well as vegetation measures, with high ground cover (i.e., broad-leaved trees). These measures should be strongly recommended for soil erosion control and surface runoff reduction. Moreover, these outcomes can be very helpful for vegetation restoration and water conservation strategies if implemented by local authorities.

Reforestation has been widely adopted to restore soil fertility and ecosystem service function in the rocky desertification region of southwestern China. However, there has been limited research concerning the stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) and nutrient resorption rate of plantations in karst ecosystems. In this study, we selected plantations of Pinus yunnanensis Franch. (PY) and Eucalyptus maideni F. Muell. (EM) in Yunnan Province. The C, N, and P concentrations and the C:N:P stoichiometry in different soil layers (0–10 cm, 10–20 cm, and 20–30 cm) were examined. The nutrient limitation and nutrient resorption efficiency were also analyzed. The leaf C and N concentrations in the PY plantation were higher than that in the EM plantation; the P concentration demonstrated the opposite trend, both in green and senesced leaves. Soil C, N, and P concentrations in the EM plantation were much greater than in the PY plantation at all three depths and decreased with the depth of the soil. In addition, the high ratios of C:P, N:P, C:Available P, and N:Available P in soil coupled with the ratios of N:P in leaves indicate that the EM plantation has a greater P deficiency than the PY plantation. In the EM plantation, the relatively low P concentrations in senesced leaves indicates efficient TP (Total phosphorus) resorption, which highlights that the high reuse proficiency of P could have favored moderating P limitation in the karst ecosystem. This research aids in understanding the stoichiometric characteristics that mediate forest properties, and provides a basis for management of vegetation in karst ecosystems.

Qinghai Lake is the largest inland saline lake on the Tibetan Plateau. Climate change and catchment modifications induced by human activities are the main drivers playing a significant role in the dramatic variation of water levels in the lake (Δh); hence, it is crucial to provide a better understanding of the impacts caused by these phenomena. However, their respective contribution to and influence on water level variations in Qinghai Lake are still unclear and without characterizing them, targeted measures for a more efficient conservation and management of the lake cannot be implemented. In this paper, data monitored during the period 1960–2016 (e.g., meteorological and land use data) have been analyzed by applying multiple techniques to fill this gap and estimate the contribution of each parameter recorded to water level variations (Δh). Results obtained have demonstrated that the water level of Qinghai Lake declined between 1960 and 2004, and since then has risen continuously and gradually, due to the changes in evaporation rates, precipitation and consequently surface runoff associated with climate change effects and catchment modifications. The authors have also pinpointed that climate change is the main leading cause impacting the water level in Qinghai Lake because results demonstrated that 93.13% of water level variations can be attributable to it, while the catchment modifications are responsible for 6.87%. This is a very important outcome in the view of the fact that global warming clearly had a profound impact in this sensitive and responsive region, affecting hydrological processes in the largest inland lake of the Tibetan Plateau.

Karst regions are widely distributed in Southwest China and due to the complexity of their geologic structure, it is very challenging to collect data useful to provide a better understanding of surface, underground and fissure flows, needed to calibrate and validate numerical models. Without characterizing these features, it is very problematic to fully establish rainfall–runoff processes associated with soil loss in karst landscapes. Water infiltrated rapidly to the underground in rocky desertification areas. To fill this gap, this experimental work was completed to preliminarily determine the output characteristics of subsurface and underground fissure flows and their relationships with rainfall intensities (30 mm h⁻¹, 60 mm h⁻¹ and 90 mm h⁻¹) and bedrock degrees (30%, 40% and 50%), as well as the role of underground fissure flow in the near-surface rainfall–runoff process. Results indicated that under light rainfall conditions (30 mm h⁻¹), the hydrological processes observed were typical of Dunne overland flows; however, under moderate (60 mm h⁻¹) and high rainfall conditions (90 mm h⁻¹), hydrological processes were typical of Horton overland flows. Furthermore, results confirmed that the generation of underground runoff for moderate rocky desertification (MRD) and severe rocky desertification (SRD) happened 18.18% and 45.45% later than the timing recorded for the light rocky desertification (LRD) scenario. Additionally, results established that the maximum rate of underground runoff increased with the increase of bedrock degrees and the amount of cumulative underground runoff measured under different rocky desertification was SRD > MRD > LRD. In terms of flow characterization, for the LRD configuration under light rainfall intensity the underground runoff was mainly associated with soil water, which was accounting for about 85%–95%. However, under moderate and high rainfall intensities, the underground flow was mainly generated from fissure flow.

When species of different abundance coexist, their ecological strategies remain uncertain. Assessing the functional diversity and niche characteristics of species with different levels of abundance contributes to understanding vegetation properties and is essential for species conservation. Based on the species abundance of 380 plots in the Gutianshan subtropical evergreen broad-leaved forest in the Zhejiang Province of China, woody plants were categorized as common species (86 species), occasional species (87 species), and rare species (79 species). Plant functional traits, including maximum height, seed dispersal modes, first flowering stage, flowering duration, and fruit length, were used to assess the functional diversity of the community of common, occasional, and rare species, while 15 environmental factors were used to evaluate their Levins’ niche breadth and Pianka’s niche overlap. The results showed that rare species have the highest functional evenness, while functional dispersion and Rao’s quadratic entropy were higher for common species (2.05 and 5.07, respectively) compared to occasional species (1.57 and 3.10) and rare species (1.35 and 2.48). Furthermore, the 15-dimensional mean value of niche breadth of common species (ranging from 0.277 to 0.955) was also higher than that of occasional (ranging from 0.193 to 0.710) and rare species (ranging from 0.100 to 0.345), and the same trend was also observed in niche overlap. The results suggest that common species have diverse functional traits and a greater ability to adapt to the environment and use resources, whereas occasional species have a limited ability to use the environment. Rare species are evenly distributed within functional space to reduce direct competition with other species, but they thrive only under specific environmental conditions, mainly following a K reproductive strategy. Niche differentiation mechanisms are important determinants of species coexistence in subtropical evergreen broad-leaved forests. In summary, more attention and greater efforts should be paid to the conservation of rare species. Our findings could help forest managers in the restoration and conservation of subtropical forests.