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Degradation of hillside alpine meadow ecosystems is a widespread problem that usually results in the fragmentation of the mattic epipedon (ME). The mattic epipedon plays a well‐known role in the hydrological cycle of alpine ecosystems due to its high water‐holding capacity. However, little is known about how ME fragmentation alters soil infiltrability—a key soil property that influences runoff and erosion processes as well as soil moisture dynamics. To address this issue, we contrasted the infiltration rates and soil and plant characteristics of preserved meadow patches (with full ME) and patches at two stages of ME fragmentation, namely, half ME and without ME. Our results showed that mattic epipedon fragmentation reduced aboveground plant biomass (mainly of sedges) by 58.6–65.6 g m−2 and root biomass by 5,643–10,054 g m−2. Soil compressive strength (11.6 kg cm−2) and total soil porosity (52%) of fragmented meadow patches without ME were significantly lower than in those with half (17.9 cm−2 and 62%, respectively) or full ME (31.7 cm−2 and 62.5%, respectively). In contrast, non‐capillary porosity and aggregate stability slightly increased with fragmentation and were highest at patches without ME. Importantly, soil infiltration rates in hillside alpine meadows greatly increased as a result of mattic epipedon fragmentation. Initial infiltration rates were approximately 10 and 20 times higher at patches with half ME and without ME (177 mm h−1 and 326 mm h−1, respectively) than at patches with the full ME (17 mm h−1). Moreover, steady‐state infiltration rates were approximately 6 and 9 times higher at patches with half ME and without ME (60 mm h−1 and 88 mm h−1, respectively) than at patches with the full ME (17 mm h−1). Overall, mattic epipedon fragmentation improved soil infiltrability by changing the soil and plant characteristics. These findings suggest that mattic epipedon fragmentation will lower runoff maintenance and have drastic effects on the water provisioning function of hillside alpine meadows on the Qinghai‐Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Large‐scale planted afforestation worldwide has exacerbated soil desiccation and led to a serious shortage of water resources for forests sustainability in semiarid areas. Consequently, thinning is discussed as an important management approach to conserve water resources and to maintain plantation forestland sustainability. Here, we explored the effects of thinning intensity on semiarid forest production and soil water supply. Three artificial forests of Populus cathayana with an age of 15 yr were selected and thinned with different intensities [1/3 amount of trees removed (T1/3), 2/3 amount of trees removed (T2/3), and using no thinning (NT) as a control]. Results showed that thinning presented a significant impact on the above‐ground three‐dimensional structure of planted forests and increased forest gaps. Meanwhile, the rainfall redistribution pattern changed significantly. Thinning increased throughfall (T1/3, 43% ± 9%; T2/3, 79% ± 18%), reduced stemflow (T1/3, −44 ± 2%; T2/3, −71% ± 2%), and increased the soil water replenishment (T1/3, 34% ± 7%; T2/3, 64% ± 19%) of forest land. Meanwhile, the dead root channel caused by thinning effectively increased the water infiltration rate and groundwater replenishment, and effectively reduced soil water deficit (T1/3, 41% ± 33%; T2/3, 57% ± 33%). Through trade‐off analysis, we found that non‐thinning aboveground biomass yields were the highest, and T2/3 yields higher water yield, while T1/3 can maintain acceptable aboveground biomass while keeping better soil water. We conclude that thinning increased soil water supply, reduced soil water deficit and maintained forestland sustainability, and there are synergies of thinning on forest production and soil water supply through rainfall redistribution for maintaining the sustainability of semiarid plantation forestlands. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms mediating biodiversity effects on ecosystem functions and services is considered a core issue in ecological and environmental sciences. We studied the direct and indirect effects of plant diversity on soil organic carbon storage and soil infiltration capacity in semiarid grasslands. Plant species diversity enhances soil organic carbon and soil infiltration capacity via multiple plant–soil feedback mechanisms in long‐term natural restoration grasslands. Plant species diversity increases community productivity, resulting in increasing soil carbon storage, which improves soil infiltration capacity by influencing soil aggregate stability and porosity. The present study indicates that plant species diversity is conducive to increasing atmospheric CO2 sequestration and reducing the risk of soil erosion. Our study provides a framework for interpreting the relationships among plant species diversity, soil organic carbon, and soil infiltration capacity to understand plant–soil feedback mechanisms in semiarid grasslands. [ABSTRACT FROM AUTHOR]

Litter crusts are integral components of the water budget in terrestrial ecosystems, especially in arid areas. This innovative study is designed to quantify the ecohydrological effectiveness of litter crusts in desert ecosystems. We focus on the positive effects of litter crusts on soil water holding capacity and water interception capacity compared with biocrusts. Litter crusts significantly increased soil organic matter compared to biocrusts and bare lands, by 2.4 times and 3.8 times, respectively. Higher organic matter content resulted in increased soil porosity and decreased soil bulk density. Meanwhile, soil organic matter can help to maintain maximum infiltration rates. Litter crusts significantly increased the water infiltration rate under high water supply. Our results suggested that litter crusts significantly improve soil properties, thereby influencing hydrological processes. Litter crusts play an important role in improving hydrological effectiveness and provide a microhabitat conducive to vegetation restoration in dry sandy ecosystems. [ABSTRACT FROM AUTHOR]

Precipitation infiltration is the most important process for soil water supply of vegetation in the arid regions. Higher infiltration rate is advantageous for vegetation growth and maintenance in the arid areas. Four grassland types ( Medicago sativa, Agropyron cristatum, Caragana korshinskii and Stipa capillata) were selected in this study. Results showed that the infiltration capacity in the legume grasslands was about 30% higher than in the gramineous grasslands and the difference was significant ( p < 0·05). Furthermore, the infiltration rate in legume shrub-grassland was 16% less than the legume grasslands, but the difference was not significant ( p > 0·05). The below-ground biomass, total porosity, capillary porosity, soil organic matters and soil aggregate were the main factors to determine the soil infiltration rates. The capillary porosity and soil aggregate of the top soil presented significant negative effects on soil infiltration rate ( p < 0·05). The below-ground biomass in 10-30 cm soil layer was the most important factor, which significantly and positively correlates with the soil infiltration rate ( p < 0·01). It is possible to conclude that the legume grasslands presented the higher soil infiltration rate and promoted precipitation infiltration in the studied area. And the legume grasslands might be a more suitable option for vegetation restoration from the perspective of soil infiltration and water supply in the arid regions. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary Soil water is one of the critical limiting factors in achieving sustainable revegetation. Soil infiltration capacity plays a vital role in determining the inputs from precipitation and enhancing water storage, which are important for the maintenance and survival of vegetation patches in arid and semi-arid areas. Our study investigated the effects of different artificial grasslands on soil physical properties and soil infiltration capacity. The artificial grasslands were Medicago sativa , Astragalus adsurgens , Agropyron mongolicum , Lespedeza davurica , Bromus inermis , Hedysarum scoparium, A. mongolicum + Artemisia desertorum, A. adsurgens + A. desertorum and M. sativa + B. inermis . The soil infiltration capacity index (SICI), which was based on the average infiltration rate of stage I (AIRSI) and the average infiltration rate of stage III (AIRS III), was higher (indicating that the infiltration capacity was greater) under the artificial grasslands than that of the bare soil. The SICI of the A. adsurgens + A. desertorum grassland had the highest value (1.48) and bare soil (−0.59) had the lowest value. It was evident that artificial grassland could improve soil infiltration capacity. We also used principal component analysis (PCA) to determine that the main factors that affected SICI were the soil water content at a depth of 20 cm (SWC20), the below-ground root biomasses at depths of 10 and 30 cm (BGB10, BGB30), the capillary porosity at a depth of 10 cm (CP10) and the non-capillary porosity at a depth of 20 cm (NCP20). Our study suggests that the use of Legume-poaceae mixtures and Legume-shrub mixtures to create grasslands provided an effective ecological restoration approach to improve soil infiltration properties due to their greater root biomasses. Furthermore, soil water content, below-ground root biomass, soil capillary porosity and soil non-capillary porosity were the main factors that affect the soil infiltration capacity. [ABSTRACT FROM AUTHOR]

• Contribution of root decay process on soil water replenishment was assessed. • The macropore formed by decayed root increased the infiltration rate at each stage. • The decayed roots maintain rapid preferential infiltration by reducing root density. • Soil water replenishment significantly increased with root decay ages. Large-scale afforestation has seriously aggravated the consumption of soil water and caused soil desiccation and even the dry soil layers, which has been restricting the survival and sustainability of vegetation in semi-arid areas. How to solve soil water deficit reasonably is an important practical problem we are facing. Here, a field experiment of the decayed roots with different times on soil water infiltration processed was conducted in planted forestland by a double-ring infiltration instrument, to determine the contribution of decayed tree roots on soil water infiltration process and replenishment. Results showed that the decayed process of tree roots in forestland could significantly reduce root density (RD) and increase the relative porosity improved by the roots (RPIR) (P < 0.05). The macropore formed by root decay could not only significantly increase the infiltration rate at each stage (P < 0.05), but also reduce the decrease rate of infiltration rate. Compared with bare land, the decayed roots of the 1–4 yr, the 5–8 yr, and the 9–12 yr increased the amount of soil water replenishment by 37.12%, 217.52%, and 259.85%, respectively. Overall, the decayed tree roots could maintain a relatively high and stable infiltration rate by reduced root density, which increased the effective replenishment of soil water of dry soil layers in forestland. These findings have potential implications for understanding the effect of decay process of tree roots on soil water replenishment, and provide a theoretical basis for the solution to dry soil layers and sustainable management of forestland in semi-arid areas. [ABSTRACT FROM AUTHOR]

• Soil water storage increased along the decreasing legume functional group proportion. • Roots decay improved the soil structure and promoted soil water infiltration. • Plant functional groups changed the surface hydrologic cycle and soil water exchange. Drought can cause and accelerate the degradation of planted legume grassland, and the changes in plant community composition can further influence soil physical properties. Here, the soil water response of different plant functional groups (legumes, grass, and forbs) were studied along a legume grassland degradation succession according to the above-ground biomass and the proportion of each functional group. In particular, changes in the soil water storage (SWS), soil properties (soil capillary porosity (CP), and soil organic matter) and plant traits (proportion of functional groups and below-ground biomass) were quantified in a continuously cultivated legume grassland for fifteen, sixteen, eighteen, and twenty-two years, without any tillage. The experimental plots were located in the semi-arid region of the Chinese Loess Plateau, in a flat area without runoff contribution. All plant and soil samples, and measurements, were obtained in a few days to minimize the temporal variability. SWS increased at 50–150 cm soil depth when the proportion of legume functional group (LFG) decreased from 70% to 5%, and this increment was ca. 20% at 50–100 cm soil layers. The Shannon-Wiener diversity index (H), the species richness (R), LFG, CP, and the non-capillary porosity (NCP) were significantly correlated with SWS (P < 0.05). The infiltration capacity significantly improved when the proportion of LFG accounted for 5%, which favored the recharge of the soil water reservoir with rainfall. Roots decay apparently improved the soil structure, and favored water infiltration, providing a suitable condition for latter vegetation growth. This study underlined the significant interaction that exists between the plant functional groups and the soil water processes during the artificial legume grassland succession. We proved that plant composition can change the surface hydrologic cycle, and the soil water exchange, in rainfed grassland. [ABSTRACT FROM AUTHOR]

• Effects of root and soil water on infiltration rate were studied during different stages. • Root diameter became the main factor affecting soil infiltration along infiltration time. • The 0–2-mm-diameter root was positively correlated with infiltration rate. • The >4.5-mm-diameter root was negatively correlated with infiltration rate. • Fine roots more determine soil infiltration potential than soil water content. Soil water is the key limiting factor for achieving sustainable revegetation. Soil infiltration rate plays an important role in determining the inputs from precipitation, which is important for the plant growth and groundwater recharge in semi-arid regions. Soil infiltration rate is generally influenced by belowground biomass (BGB), soil water content (SWC) and other soil properties (total soil porosity, soil mean weight diameter and soil organic carbon). The aim of this study is to understand the effects of plant roots, SWC and other soil properties on soil infiltration rate, and to identify the main factor affecting soil infiltration rate. This study investigated the total soil porosity (TP), soil mean weight diameter (MWD), soil organic carbon (SOC), SWC and plant roots of five grasslands (Bromus inermis , Trifolium repens , Panicum virgatum , Medicago sativa and Miscanthus sinensis). An automatic measurement system of point source device was used to quantify the soil infiltration rate. Results showed that SWC significantly affected the initial infiltration rate (P < 0.05), but plant roots gradually became the main factor affecting soil infiltration rate as the increasing infiltration time. The percentage of root volume (PV) of 0–2 mm was positively correlated with infiltration rate, while the PV of >4.5 mm was negatively correlated with infiltration rate. Our results indicated that fine roots could increase soil organic matters and form soil pores, thus more determining the potential of soil infiltration than soil water content during the short-term vegetation restoration in semi-arid regions. [ABSTRACT FROM AUTHOR]

Grasslands with dense fibrous roots and higher biological soil crust coverage generally show great performance of sediment reduction and runoff maintenance during the two-year experiments. Gramineae grasslands are effective in maintaining runoff and reducing sediment, which can be considered as a suitable management practice to achieve the sustainability of the socio-ecological systems during vegetation restoration in semi-arid areas. Large-scale vegetation restoration generally reduces local water yield and influences river ecosystem health. Thus, scientific evaluation of vegetation restoration consequences is necessary for maintaining the stability of the surface water system and water cycle in semi-arid regions. In this study, we compared the efficiencies of different typical grasslands in regulating runoff and sediment yields and proposed feasible suggestions suiting for local environments. Four grasslands, including two Gramineae species (Elymus dahuricus and Bromus inermis) and two legume species (Medicago sativa and Trifolium repens), were tested during a two-year period with simulated rainfall experiments, and using bare land as control. Three replicates were done for each treatment, and fifteen plots with a slope of 20° were constructed. Three indices were used to assess the runoff and sediment yields reduction capacity of the grasslands, including runoff reduction benefit (RRB), sediment reduction benefit (SRB), and soil infiltration rate (SIR). The results showed that RRB and SRB were significantly different (P < 0.05) among treatments across the two-year experiments. The values of SRB increased considerably in the second year. In particular, the values of SRB for E. dahuricus and B. inermis was 98.79% and 98.07%, respectively, while that of RRB was −11.84% and 4.01%, respectively. The two Gramineae grasslands showed greater effectiveness in sediment reduction and runoff maintenance than the two legume species owing to the dense fibrous roots and higher biological soil crust coverage. Therefore, Gramineae grasslands can be considered as a suitable management practice to achieve the socio-ecological sustainability of the semi-arid areas during vegetation restoration. [ABSTRACT FROM AUTHOR]

• Shrub encroachment and severe degradation reduced Cyperaceae coverage and root biomass. • Shrub encroachment and severe degradation significantly increased soil non-capillary porosity. • Reduction of Cyperaceae spp. and increase of non-capillary porosity increased infiltration rate. • The two divergent successions both increased cumulative infiltration and evapotranspiration. • Short-term grazing exclusion presented little effect on soil infiltration rate. Alpine meadow ecosystem are undergoing the divergent successions under the influence of global climate warming and overgrazing by herbivores, which may profoundly impact the ecohydrology function of alpine meadow ecosystem. However, few studies reported the effects of the divergent successions on ecohydrological process of alpine meadow. Here, we report an in situ experiment to examine the effects of the divergent successions on soil pore structure, infiltration rate and evapotranspiration of the two types of divergent-succession meadows (the shrub-encroached meadow and the severely degraded meadow), compared to the normal alpine meadow. Results showed that both the shrub-encroached meadow and the severely degraded meadow significantly reduced the dominant Kobresia spp. (Cyperaceae family) coverage, soil compactness, and belowground biomass, but significantly increased soil non-capillary porosity (P < 0.05) compared to the normal alpine meadow. Soil infiltration rate was significantly negatively correlated with Kobresia spp. coverage, soil compactness and belowground biomass, while significantly positively correlated with soil non-capillary porosity (P < 0.05). Therefore, the shrub-encroached meadow and the severely degraded meadow increased soil infiltration rates not only by reducing the dominated Kobresia spp. (Cyperaceae family) coverage and belowground biomass, but also by increasing soil non-capillary porosity. Compared with the normal alpine meadow, the cumulative infiltration and evapotranspiration increased by 245.25% and 45.19% in the shrub-encroached meadows, and increased by 208.23% and 29.95% in the severely degraded meadow. However, short-term grazing exclusion presented little effect on soil infiltration rate in alpine meadows. Overall, the divergent successions of alpine meadows had a greater impact on soil water replenishment and evapotranspiration than the short-term grazing exclusion. These findings can help to better understand the impacts of the divergent community succession on the ecohydrological process in alpine grassland ecosystem. [ABSTRACT FROM AUTHOR]

• Root channels by the decayed roots and preferential flow of alfalfa grassland were studied. • Initial infiltration rate of M. sativa increased by 27.70% resulted from preferential flow of decayed roots. • Steady infiltration rate of M. sativa increased by 31.80% resulted from preferential flow of decayed roots. • Average root channel diameter and root channel area are positively correlated with infiltration rate. • Preferential flow of decayed roots is important in increasing soil water infiltration and supply. Soil water infiltration is an important part of the land surface hydrological cycle, and plays an important role in the hydrological response of the soil, such as soil erosion. High infiltration rates favor an increase in the soil water storage capacity that allows maintaining vegetation restoration in arid and semi-arid regions. Alfalfa (Medicago sativa L.) is a quality perennial legume grassland, which is widely planted in semi-arid areas. In this study, the effects of the root channels formed by the decay of alfalfa on preferential flow were evaluated as a driving force to improve soil water infiltration and soil water supply. A double-ring infiltrometer (30-cm inner diameter and 60-cm outer diameter) was used to measure the infiltration process with the falling head method. Methylene blue was used to visualize the pathways followed by the infiltrated water. The results showed that the initial infiltration rate in the alfalfa grassland increased by 27.7%, compared with the control bare land, and the total cumulative infiltration was 1.13 times higher. The steady infiltration rate of the grassland increased by 31.8% compared to the bare land. The root channel diameters were measured with a Vernier caliper, and the average root channel area (RCA) was calculated through the average root channel diameter (ARCD). The values of ARCD and RCA were significantly and positively correlated with the infiltration rates, being the coefficients of determination 0.815 and 0.789, respectively. Our results indicated that root channels formed by the decayed roots of alfalfa played an important role in increasing soil water infiltration and soil water supply under semi-arid conditions. Our research improves the understanding of the hydrological cycle processes at the plant-soil interface in semi-arid areas. [ABSTRACT FROM AUTHOR]

• Blocking effects of Pisha sandstone on water leakage in sandy land were examined. • Inserted Pisha sandstone in sandy land changed the vertical distribution of soil water. • Inserted Pisha sandstone at 10–15 cm depth caused high permeability resistance. • Inserted Pisha sandstone effectively hindered the downward leakage of sandy soil water. Quick water seepage in sandy soils results in a serious restriction for ecological restoration, becoming a worldwide urgent research issue in arid areas. Search for practical solutions are focused on reserving the limited rainfall into topsoil layer to meet plant water demand. Based on fieldwork, this study evaluates the blocking effects of Pisha sandstone on soil water leakage, by inserting sandstone layers in the different soil depths (10–15 cm, 20–25 cm, 30–35 cm), which act as isolation layers within the sandy soil. Results showed that the inserted Pisha sandstone layers significantly decreased the soil water infiltration rates at the different stages and cumulative infiltration. The inserted sandstone layer at the depth of 10–15 cm presented the highest permeability resistance, and its initial infiltration rate, stable infiltration rate and average infiltration rate decreased by 102.42 mm h−1, 144.30 mm h−1 and 132.79 mm h−1, respectively. Meanwhile, the soil water content in the 5–10, 20–25, and 30–35 cm soil layers increased by 2.17%, 2.20%, and 1.37%, respectively, due to the inserted Pisha sandstones. This experimental study proves that the insertion of Pisha sandstones effectively hinders the downward penetration of soil water in sandy soil. These findings provide a new alternative for an effective solution of the fast water leakage problem of sandy land. [ABSTRACT FROM AUTHOR]

• Poor palatability allows eco-grass to accumulate litter in grassland community. • Eco-grass reduces soil loss by increasing rainfall interception and water infiltration. • Eco-grass has ecological benefits and soil and water conservation benefits. Ecological grasses (eco-grass) have poor palatability and are less popular than forage grasses, receiving little attention for many years, despite their increased survival regarding livestock on the Qinghai-Tibetan Plateau. Eco-grass restoration has the functions of increasing vegetation coverage, preventing soil and water loss, conserving water sources, and preventing pika and insect pests. However, the effects of the eco-grass on soil and water conservation are still unclear. Here, a field experiment was conducted to determine the effects of an eco-grass species (Elymus tangutorum) on the processes of soil and water loss in alpine hillslopes grasslands on the eastern Qinghai-Tibetan Plateau. The results showed that the soil loss rate decreased with the increase of litter biomass in the presence of the selected eco-grass. The presence of eco-grass reduced the soil loss rate by 65% and this was mainly associated with the increase of the rainfall infiltration rate and litter interception rate. Our findings showed that eco-grass could take into account both soil and water conservation and ecological benefits in alpine hillslope grasslands. Therefore, eco-grass should be considered and extensive application to maintain the multifunctions and stability of artificial hillslopes grassland on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Mulching is one of the most common post-fire management techniques, which has been widely studied at the global scale. However, more research is needed on the hydrological effects of mulching in forest ecosystems under Mediterranean semi-arid conditions. This study has evaluated water infiltration, surface runoff and soil loss using a portable rainfall simulator in Central-Eastern Spain after post-fire treatments. In this area, a large wildfire recently affected a pine forest, and the burned soil was mulched using wheat straw (dose of 0.3 kg/m2) or wood chips (2 kg/m2) on plots with two different slopes (about 30%, lower slope, and 50%, higher slope). The study has shown that the soil condition (burned control vs. soils mulched with straw or wood chips) and slope (lower vs. higher) did not significantly influence the water infiltration. However, the mean infiltration of the soils mulched with straw were higher (+40% and + 17%, respectively) compared to both the control and the plots mulched with wood chips. Moreover, lower surface runoff (−23%) was measured in the mulched soils compared to the control plots. The soil mulching with straw was more effective at decreasing the runoff coefficient (−31%) compared to plots treated with wood chips (−18%) and the control areas. Soil loss was significantly lower in plots treated using straw (−87% compared to the burned and not treated soils) compared to wood chips (−54%). Peaks of 90–95% of reduction in the soil loss were even recorded in the steeper soils. Finally, we suggest the application of wheat straw rather than wood chips, since the wheat straw mulch material provides a higher soil cover (on average 73% against 48% of wood chips) and therefore is more indicated to reduce the hydrological response in burned soils, as confirmed by the lower runoff (in the average − 16%) and erosion (−73%) measured in this experiment on both gentler and steeper soils. [Display omitted] • Rainfall was simulated on burned forest soils mulched with straw and wood chips. • Straw was more effective than wood chips at decreasing surface runoff coefficient. • This reduction was more evident in soils with lower slopes. • Soil loss decreased by 87% on straw-mulched soils and by 54% using wood chips. • Straw mulch provides a higher soil cover than wood chips and is thus more advisable. [ABSTRACT FROM AUTHOR]

• Effects of forestland-to-farmland conversion on soil water replenishment were evaluated. • Forestland-to-farmland conversion changed soil porosity and water holding capacity. • Cumulative infiltration improved by 100.33% after forestland-to-farmland conversion. • Forestland-to-farmland conversion short-term effectively replenished soil water deficit. The increasing global vegetation aggravated the consumption of soil water and caused soil desiccation, which may result in a threat to the survival and sustainability of vegetation, especially in semi-arid and arid areas. How to solve soil water deficit caused by afforestation is an important practical problem. Here, a field experiment of soil water infiltration and replenishment was conducted before and after forestland-to-farmland conversion. Results showed that the cumulative infiltration of each stage (the initial stage, the transitional stage, and the stable stage) was the highest in farmland, followed by forest interspace, and the lowest in forest understory. The non-capillary porosity at 0–20 cm soil layer in farmland was higher than that in forest understory and interspace, which positively improved the infiltration accumulation in the initial stage. Thus, the cumulative infiltration in initial stage of farmland (28.93 mm) was significantly higher than that of forest understory (19.45 mm). Moreover, soil water at the depth of 0–160 cm soil layer was replenished with short term after forestland-to-farmland conversion. It is concluded that forestland-to-farmland conversion could improve soil water infiltration rate and cumulative infiltration by changing porosity, and effectively replenished soil water storage in the short term. These findings have potential implications for effective mitigation of soil water deficit caused by afforestation, and provide a new idea or method for the solution to dry soil layers caused by artificial forestland in semi-arid areas. [ABSTRACT FROM AUTHOR]

• Shrub encroachment enhanced soil infiltration capacity of alpine meadow. • Infiltration rates were highest at the heavily encroached alpine meadow. • Shrub encroachment increased infiltrability by changing plant and soil conditions. • Shrub encroachment inhibits sedges growth, creating dead root channels. • Shrubs reduced soil moisture, reduced compaction, and enhanced aggregate stability. Due to global changes and anthropogenic disturbances shrubs are widely encroaching into alpine meadows, which may have profound impacts on the ecohydrological functioning of these key ecosystems. This phenomenon is particularly alarming in the alpine meadows of the Qinghai-Tibetan Plateau, the headwaters for many of Asia's largest rivers. However, little is known about the extant in which shrub encroachment alters the infiltration capacity of those soils. Here we examined the effects of shrub encroachment on the plant community and soil infiltration processes by contrasting vegetation and infiltration variables between three areas: a reference alpine meadow, an alpine meadow lightly encroached by smaller shrubs, and an alpine meadow heavily encroached by larger shrubs. We found that shrub encroachment reduced herbaceous plants aboveground biomass by 10–24 g m−2 and root biomass by 1346–2239 g m−2. The sedge functional group was gradually replaced by forbs. Initial infiltration rates gradually increased with shrub encroachment, and were approximately doubled and tripled at the earlier and later stages of encroachment, respectively. Overall, shrub encroachment improved the soil infiltrability by changing soil conditions and inhibiting herbaceous species due to the reduction of surface mattic epipedon and the formation of dead root channels. These findings suggest that the rapid transformation of alpine meadows into shrublands could have drastic effects on the surface runoff and streamflow dynamics of the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Soil biocrusts are an important type of surface cover in sandy ecosystems, covering about 12% of the terrestrial surface. The biocrusts affect the hydrological process of sandy land by means of inhibiting soil water initial infiltration and exchange in the topsoil, and thus hinder vegetation recovery of sandy land. This study was conducted to explore the response of the soil infiltration performance and soil water content underneath the biocrusts (dominated by lichen and moss) in litter cover. The differences in soil infiltration rate and soil water content among five treatments (bare sandy land, physical crusts, biocrusts, litter covered biocrusts, and litter crusts) in the Mu Us Desert were investigated by the single-rings infiltrometer and the oven-drying method. Results showed that the initial soil infiltration rate of litter covered biocrusts and litter crusts were 215% and 280% higher than that of biocrusts. The average soil water content in litter crusts (11.7%) and litter covered biocrusts (10.2%) were 3.3 and 2.9 times greater than that in biocrusts, respectively. Our results indicated that litter cover could break the water repellency of biocrusts, increase the initial soil infiltration rates, and increase the soil surface water content. This criterion will help promote ecological restoration in sandy ecosystems. • Litter cover significantly improves the soil porosity of biocrusts • Soil water content of litter covered biocrusts was 2.9 times higher than that of biocrusts • Soil infiltration rate of different treatments was tested by the single-rings infiltrometer • Litter cover reduces soil water repellency of biocrusts and enhances soil water infiltration [ABSTRACT FROM AUTHOR]

• Effects of root morphological characteristics on soil water infiltration rates was studied. • Root length density and root surface area were negatively correlated with infiltration rate. • Root length density (5−30 cm) and root surface area (10−20 cm) influence infiltration rates. • It provide insights for plant root morphological characteristics on the infiltration processes. Surface water infiltration is an important process to meet plant water needs and an important part of the hydrological cycle via groundwater recharge, with special relevance in semi-arid regions. This study evaluated the relationships between grassland plant root morphological characteristics and soil water infiltration rates (IR: initial, steady and average). For this purpose, five artificial homogeneous grasslands (Melilotus suaveolens , Medicago sativa , Panicum virgatum , Bromus inermis and Miscanthus sinensis) without irrigation or fertilization were studied in the Loess Plateau. The observed steady IR were significantly different between the 1-year grasslands: M. suaveolens > M. sativa > P. virgatum > B. inermis > M. sinensis. The root length density and root surface area were negatively correlated with the average, initial and steady IR at different soil depths (p < 0.05). However, the root volume did not significantly influence IR. The stepwise multiple regression determined that the main factors controlling IR were the root length density at the depth of 5−30 cm and root surface area at the depth of 10−20 cm. Our results provide insight into the influence of grassland root morphological characteristics on water infiltration in drylands and are of interest for soil water supply programs in forage production. [ABSTRACT FROM AUTHOR]

• Alpine soil water infiltration capacity was increased along the alfalfa planting age. • Relationship between soil water content and infiltration rate changed along infiltration process. • Soil water infiltration capacity was positively related to root dry weight density. • Alfalfa planting improved alpine soil infiltrability, and this upgrade increased with the age growth. The Qinghai-Tibetan Plateau is undergoing serious water and soil conservation problem resulted from grassland degradation, that is not conductive to the sustainability of grassland ecologicla function and agriculture productivity. The soil infiltrability has significance in reducing runoff yield and soil loss. However, characterization of the soil infiltration capacity of planted grasslands, such as alfalfa (Medicago Sativa), with different growing years in this high-altitude alpine region is still lacking. In this study, the variation of soil infiltration rate and characteristics were analyzed in alfalfa grasslands with three growth years (two-, four- and seven-year-old). A corn cropland was used as the control field, and the infiltration was monitored using the automatic soil infiltrability measurement system. To determine the influence factors on infiltration rate (IR), soil characteristics and root dry weight density (RDWD) at 0–30 cm soil depth were measured. The results indicated that the comprehensive index of soil water infiltration capacity (FIR) of the seven-year-old alfalfa grassland (0.69) was the highest, followed by the two- (0.05) and four-year-old (0.11) grasslands, being these values significantly higher than that of the corn field (-0.85, P < 0.05). SWC was positively correlated with IR during the fast infiltration stage (IR-I). The soil bulk density and organic matter were negatively correlated with IR, while RDWD was positively related to IR. Our results showed that alfalfa planting improved soil infiltrability, and this upgrade increased with the age growth. This study provided significant information to introduce soil-erosion-control practices for alpine soil and highlights the importance of ecological function of planted grasslands in alpine area of the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The accurate measurement of soil infiltration rates is a challenging task in hydrological studies, as they are governed by complex interactions between the plant and soil components. To explore the effects of plant roots and soil moisture (SM) on infiltration process, an automatic measurement system based on a point source device was used to determine infiltration rates at different cultivated grasslands (leguminous, gramineous and mixed) in an arid region of China. The results showed that SM and plant roots significantly affected the infiltration process at different stages in the three grasslands. The soil infiltration rates were negatively correlated to SM, but a positive correlation was observed with the below-ground biomass (BGB). SM was the main factor influencing the infiltration rates in the initial stage of infiltration, whereas both SM and BGB determined the steady-state infiltration rates. The influence of the combined effects of SM and plant roots decreased over infiltration time. The decreased rate of determining coefficient showed that SM was more influent than plant roots. These results may contribute to interpret the observed higher soil infiltration capacity in the leguminous grasslands than in the gramineous and the mixed grasslands, and were conducive to better understand the effects of plant and soil properties on infiltration processes in arid areas. • Soil moisture and plant roots determined soil infiltration capacity by stages were studied. • Soil moisture is a main factor to influence negatively infiltration capacity in initial stage. • Soil moisture and plant roots codetermined the infiltration rate in steady stage. • Influences of soil moisture and roots are diminishing with the duration of infiltration time. [ABSTRACT FROM AUTHOR]