Does forest restoration influence soil infiltrability? A case study in the restored woodland of Sierra de ávila(Central Spain)

Infiltration,as a major component of the hydrological cycle,plays an important role in ecosystems,river flooding,and soil erosion.Therefore,this process has been studied on different soils,with different vegetation cover,and under different climate conditions.However,it is still necessary to know how infiltration rates depend on land degradation,vegetation cover,forest management,and forest restoration,since soil infiltration is related to soil hydrological function and hydrological ecosystem services.The aim of our study is to analyze the way reforestation and check dam construction have helped to improve soil infiltration rates in comparison with old,degraded land,different soils and vegetation covers in Central Spain.Therefore,three infiltration tests were carried out by means of a simple methacrylate infiltrometer ring,in four sampling plots,for five types of land use:(i) native holm oak forest,(ii) 60-year-old reforested pine wood,(iii) shrubs,(iv) sediment wedges of check dams,and(v) gullies and degraded hillslopes.Our results show much higher infiltration rates in the soil of 60-yearold pine reforestation sites(1198.00 mm·h^(-1)),and in the sediment wedges of check dams(1088.00 mm·h^(-1)),than in those of degraded hillslopes(365.00 mm·h^(-1)) and shrubland(420.80 mm·h^(-1)).The rates were also shown to be close to those from the remaining patches of native holm oak woodland(770.40 mm·h^(-1)).We also found that organic matter,humus and litter depth,and height of vegetation and cover,all improve soil infiltration rates,while slope degree,presence of coarse elements,stoniness,clay content,bulk density,and electric conductivity inhibit the rates.It was additionally seen that pine reforestation and check dam construction caused degraded land to recover its hydrological conditions to a level that is quite close to that of the ancient oak holm native forest,alongside ameliorating the hydrological cycle in the watershed.This information will be very useful for decisionmaking processes related to land restoration projects,forest management,and environmental policy.

Soil Moisture Response to Rainfall in Forestland and Vegetable Plot in Taihu Lake Basin,China

Soil moisture and its spatial pattern are important for understanding various hydrological,pedological,ecological and agricultural processes.In this study,data of rainfall and soil moisture contents at different depths(10 cm,20 cm,40 cm and 60 cm) in forestland and vegetable plot in the Taihu Lake Basin,China were monitored and analyzed for characteristics of soil moisture variation and its response to several typical rainfall events.The following results were observed.First,great temporal variation of soil moisture was observed in the surface layer than in deeper layer in vegetable plot.In contrast,in forestland,soil moisture had similar variation pattern at different depths.Second,initial soil moisture was an important factor influencing the vertical movement of soil water during rainfall events.In vegetable plot,simultaneous response of soil moisture to rainfall was observed at 10-and 20-cm depths due to fast infiltration when initial soil was relatively dry.However,traditional downward response order occurred when initial soil was relatively wet.Third,critical soil horizon interface was an active zone of soil water accumulation and lateral movement.A less permeable W-B soil horizon interface(40-cm depth) in vegetable plot can create perched water table above it and elevate the soil water content at the corresponding depth.Fourth,the land cover was an effective control factor of soil moisture during small and moderate rainfall events.In the forestland,moderate and small rainfall events had tiny influences on soil moisture due to canopy and surface O horizon interception.Fifth,preferential flow and lateral subsurface interflow were important paths of soil water movement.During large and long duration rainfall events,lateral subsurface flow and preferential flow through surface crack or soil pipe occurred,which recharged the deep soil.However,in more concentrated large storm,surface crack or soil pipe connected by soil macropores was the main contributor to the occurrence of preferential flow.Findings of this study provide a theoretical foundation for sustainable water and fertilizer management and land use planning in the Taihu Lake Basin.

Revegetation with artificial plants improves topsoil hydrological properties but intensifies deep-soil drying in northern Loess Plateau,China

Knowledge about the effects of vegetation types on soil properties and on water dynamics in the soil profile is critical for revegetation strategies in water-scarce regions, especially the choice of vegetation type and human management measures. We focused on the analysis of the effects of vegetation type on soil hydrological properties and soil moisture variation in the 0–400 cm soil layer based on a long-term（2004―2016） experimental data in the northern Loess Plateau region, China. Soil bulk density（BD）, saturated soil hydraulic conductivity（Ks）, field capacity（FC） and soil organic carbon（SOC） in 2016, as well as the volumetric soil moisture content during 2004–2016, were measured in four vegetation types, i.e., shrubland（korshinsk peashrub）, artificial grassland（alfalfa）, fallow land and cropland（millet or potato）. Compared with cropland, revegetation with peashrub and alfalfa significantly decreased BD and increased Ks, FC, and SOC in the 0–40 cm soil layer, and fallow land significantly increased FC and SOC in the 0–10 cm soil layer. Soil water storage（SWS） significantly declined in shrubland and grassland in the 40–400 cm soil layer, causing severe soil drought in the deep soil layers. The study suggested that converting cropland to grassland（alfalfa） and shrubland（peashrub） improved soil-hydrological properties, but worsened water conditions in the deep soil profile. However, natural restoration did not intensify deep-soil drying. The results imply that natural restoration could be better than revegetation with peashrub and alfalfa in terms of good soil hydrological processes in the semi-arid Loess Plateau region.

西秦岭森林生态旅游区不同林分类型土壤水文效应研究——以麦积山风景区为例

为揭示麦积山风景区不同林分土壤水文效应,采用环刀法对麦积山风景区5种林分林下土壤持水性进行研究。结果表明:5种典型不同林分类型林地土壤0~30 cm容重平均值范围为1.14~1.48 g·cm3,土壤总孔隙度均值为43.40%~54.86%,其中锐齿栎林最大,油松+锐齿栎林和油松林次之,油松+辽东栎林最小。不同林分林地土壤最大持水量以锐齿栎林(548.56 t·hm-2)最大,油松+辽东栎林(434.02 t·hm-2)最小,说明锐齿栎林土壤持水能力最强。土壤稳渗速率以油松+锐齿栎林最大(1.52 mm·min-1),油松林最小(1.21 mm·min-1)。5种不同林分林下土壤入渗时间和入渗速率存在着较好的幂函数关系。

Response of soil hydrological processes to soil rock fragments:A global Meta-analysis

The rock fragment(RF)has been widely observed in the soil solum or on the soil surface.It regulates soil hydrological processes(SHPs)and thus has great impacts on soil and water conservation.However,responses of SHPs to RF characteristics(position,content,coverage area,mulching thickness,and size)remain unclear.Based on the dataset extracted from 168 published studies,effects of RF characteristics on SHPs(soil loss rate,evaporation rate,surface runoff rate,infiltration rate,soil water content,and soil water storage)and saturated hydraulic conductivity(Ks)were discussed in this study.Results showed that RFs completely inserted into the soil solum(CO_INS)improved the Ks by 6.9%,runoff rate by 12.8%,and soil loss rate by 22.3%,while it reduced the evaporation rate by 30.7%,infiltration rate by 15.4%,and soil water content by 9.9%.With the RF content(kg kg−1)increasing,its effects on these SHPs were strengthened.The RFs resting on the surface and partially covering soil surface(PA_COV)improved the infiltration rate but reduced the evaporation rate by 36.9%,surface runoff rate by 25.4%,and soil loss rate by 59.3%.This in turn enhanced soil water content and storage.However,as the RF coverage(%in area)increasing,the cross-sectional area of water flow decreased,and thus the infiltration rate reduced.The RFs completely mulch on the soil surface(CO_MUL)reduced the evaporation rate by 59.5%and infiltration rate by 76.5%but improved the soil water content and storage.Except the infiltration rate,the effects of CO_MUL on SHPs were strengthened as mulch thickness(cm)increased.The RFs partially embedded into soil surface(PA_EMB)promoted surface runoff rate by 15.3%,soil loss rate by 34.7%,and soil water content by 24.3%,but reduce the infiltration rate.However,the surface runoff rate was reduced at high embedded coverage due to increased tortuosity of water flow.In addition,the RF size exerted weaker effects on SHPs than RF positions,content,coverage,and mulch thickness.Our findings enhanced the understanding of SHP responses to RFs characteristics,which would be important for relate soil and water modeling and management.

Inhibiting soil loss and runoff from small plots induced by an individual freeze-thaw cycle using three rangeland species

This study investigated the role of three rangeland species viz.Agropyron trichophorum,Medicago sativa,and Lolium prenne on mitigating of effects of a freeze-thaw(FT)cycle on runoff generation and soil loss from small experimental plots.Small plots(0.5×0.5m)were prepared in three replicates for control(i.e.,under a FT cycle only)and treatments(i.e.,individually planted with the study species and subject to a FT cycle).The treated plots were then placed at a slope of 20%and subjected to simulated rainfall with intensity of 70 mm h-1 and 30 min duration.The results of the study showed a significant effect(P<0.05)of the plants on controlling runoff and soil loss after a FT cycle.Also,the detrimental effects of the FT cycle due to performance of ice lenses and formation of an active melting layer in the soil surface were ameliorated by the presence of litter on the soil and root-binding effect of the plants.Time to runoff increased by 54,111 and 10%,runoff volume decreased by 27,68 and 0.4%and soil loss changed by-34,-62,and+6.5%in the plots planted with A.trichophorum,L.prenne and M.sativa,respectively.The results of the current study indicated that L.prenne had the maximum benefit on reducing runoff and soil loss from the plots undergoing a FT cycle.