Estimation and testing of linkages between forest structure and rainfall interception characteristics of a Robinia pseudoacacia plantation on China’s Loess Plateau

Understanding the interaction between canopy structure and the parameters of interception loss is essential in predicting the variations in partitioning rainfall and water resources as affected by changes in canopy structure and in implementing water-based management in semiarid forest plantations.In this study,seasonal variations in rainfall interception loss and canopy storage capacity as driven by canopy structure were predicted and the linkages were tested using seasonal filed measurements.The study was conducted in nine 50 m×50 m Robinia pseudoacacia plots in the semiarid region of China’s Loess Plateau.Gross rain-fall,throughfall and stemflow were measured in seasons with and without leaves in 2015 and 2016.Results show that measured average interception loss for the nine plots were 17.9% and 9.4% of gross rainfall during periods with leaves (the growing season) and without leaves, respectively. Average canopy storage capacity estimated using an indirect method was 1.3 mm in the growing season and 0.2 mm in the leafless season. Correlations of relative interception loss and canopy storage capacity to canopy variables were highest for leaf/wood area index (LAI/WAI) and canopy cover, fol-lowed by bark area, basal area, tree height and stand density. Combined canopy cover, leaf/wood area index and bark area multiple regression models of interception loss and canopy storage capacity were established for the growing season and in the leafless season in 2015. It explained 97% and 96% of the variations in relative interception loss during seasons with and without leaves, respectively. It also explained 98% and 99% of the variations in canopy storage capacity during seasons with and without leaves, respectively. The empiri-cal regression models were validated using field data col-lected in 2016. The models satisfactorily predicted relative interception loss and canopy storage capacity during seasons with and without leaves. This study provides greater under-standing about the effects of changes in tree canopy structure (e.g., dieback or mortality) on hydrological processes.

Surface Treatments Effect on Rainfall Canopy Interception and Runoff-Rainfall Ratio for in-Field Rainwater Harvesting

The purpose of this study was to ascertain the effectiveness of surface treatments to quantify the partitioning of rainwater falling on the runoff strips and basins as well as to determine the fraction of rainwater available to intercept by maize canopy and infiltrate into the root zone. The rainfall canopy interception （RCI） was estimated as a function of basin leaf area ratio per rain event. The runoffrainfall （RR） ratio was determined for both a single rainfall event and the whole growing season. Infiltration ratio of basin to runoff area was analysed for every unit millimeter of water that infiltrate in the runoff section, some additional of water will infiltrate in the basin area. The plateau value of RCI-rainfall relationships rendered about double in the wider （1.0-1.1 mm） compared to the narrow runoff strips （0.5-0.6 mm）. Statistically, the combined surface treatments （RSL x ML） affected the RR ratio with higher efficiency in bare 1 m runoff （27%） and the lower efficiency group （〈 10%） is associated with the widest runoff length covered with mulch. Variations in fractions of rainwater that can infiltrate into basins and runoffareas can lead one to select alternative strategies for water harvesting techniques.

Variable hydrological effects of herbs and shrubs in the arid northeastern Qinghai-Tibet Plateau,China

This study aims to assess the hydrological effects of four herbs and four shrubs planted in a selfestablished test area in Xining Basin of northeastern Qinghai-Tibet Plateau, China. The RainfallIntercepting Capability(RIC) of the herbs and shrubs was evaluated in rainfall interception experiment at the end of the third, fourth and fifth month of the growth period in 2007. The leaf transpiration rate and the effects of roots on promoting soil moisture evaporation in these plants were also assessed in transpiration experiment and root-soil composite system evaporation experiment in the five month's growth period. It is found that the RIC of the fourstudied herbs follows the order of E. repens, E. dahuricus, A. trachycaulum and L. secalinus; the RIC of the four shrubs follows the order of A. canescens, Z. xanthoxylon, C. korshinskii and N. tangutorum. The RIC of all the herbs is related linearly to their mean height and canopy area(R^2 ≥ 0.9160). The RIC of all the shrubs bears a logarithmic relationship with their mean height(R^2 ≥ 0.9164), but a linear one with their canopy area(R^2 ≥ 0.9356). Moreover, different species show different transpiration rates. Of the four herbs, E. repens has the highest transpiration rate of 1.07 mg/(m^2·s), and of the four shrubs, A. canescens has the highest transpiration rate(0.74 mg/(m^2·s)). The roots of all the herbs and shrubs can promote soil moisture evaporation. Of the four herbs, the evaporation rate of E. repens root-soil composite system is the highest(2.14%), and of the four shrubs,the root-soil composite system of A. canescens has the highest evaporation rate(1.41%). The evaporation rate of the root-soil composite system of E. dahuricus and Z. xanthoxylon bears a second-power linear relationship with evaporation time(R^2 ≥ 0.9924). The moisture content of all the eight root-soil composite systems decreases exponentially with evaporation time(R^2 ≥ 0.8434). The evaporation rate and moisture content of all the plants' root-soil composite systems increases logarithmically(R^2 ≥ 0.9606) and linearly(R^2 ≥ 0.9777) with root volume density. The findings of this study indicate that among the four herbs and four shrubs, E. repens and A. canescens possess the most effective hydrological effects in reducing the soil erosion and shallow landslide in this region.

Simulating Spatial Distribution of Canopy Rainfall Interception of Forests in China

The canopy rainfall interception modei linked to environmental conditions and biological features is established on the basis of stationary observation and measurements in China. Upscaling from site observation to regional Ievel estimation of canopy rainfall interception has been made. The potential interception value of forests during the rainfall season in China according to rainfall records of May, July and September in the year 1982, has been simulated and mapped under the GIS software package Idris...

Rainfall partitioning in young clonal plantations Eucalyptus species in a subtropical environment,and implications for water and forest management

Different canopy characteristics of industrial eucalyptus may lead to differences in water evaporation and availability to plants.This study aims to understand rainfall partitioning in a young clonal plantation(age of 2-4.5 years)of three eucalyptus species by relating tree parameters:diameter at breast height,total height,and leaf area index.We measured rainfall,throughfall,stemflow and litter interception,along with the tree parameters.The eucalyptus trees had rainfall interception varying between 22 mm(for 178 mm of rainfall)and 42 mm(for 87 mm of te rainfall),throughfall between 106 mm(for 186 mm of rainfall)and 44 mm(for 74 mm of rainfall),and stemflow between 0.5 mm(for 92 mm of rainfall)and 1.4 mm(for 24 mm of rainfall).For the three species,rainfall interception varied between 12 and 48%,throughfall between 57 and 90%,and stemflow between 0.3 and 5.4%.The coefficient of determination between interception and rainfall was 0.76,indicating interception depends on other variables,possibly including antecedent rainfall,rainfall intensity,and seasonality.Interception decreased with a reduction in leaf area index caused by eucalyptus defoliation.The E.benthamii had 0.75 mm of throughfall per 1 mm of rainfall,whereas in E.dunnii and E saligna,these ratios were 0.71 and 0.68,respectively.Stemflow in E.benthamii and E.dunii had a higher positive relationship with the diameter at breast height of the trees,whereas in E.saligna the highest relationship was with the rainfall.These results contribute to establishing management strategies,such as choosing suitable eucalyptus species to local climate,and to improve the synchronization of crop-demand versus soil-water-supply while maintaining streamflow to fulfill ecological and production needs.

Variation in ecosystem services of street tree assemblages can guide sustainable urban development

Urban afforestation is an important strategy for promoting sustainable urban development.In cities where large new green spaces are not available,the planting of curbside trees is deemed to be an important afforestation strategy.However,variations in the ecosystem services provided by street tree assemblages across socioeconomic gradients have been unexplored.We examined such variations in ecosystem services provided by street tree assemblages along an urban–suburban continuum.Our findings were as follows.(i)Not all ecosystem services showed increasing trends along the urban–suburban continuum.Some ecosystem services at the street tree assemblage level,such as air purification and rainfall interception were prominent in areas of high urbanization intensity.(ii)Diverse ecosystem service trends were found in relation to differential characteristics of street trees assemblages.Structural properties of street tree assemblages,such as tree density and age structure,are likely key factors influencing variations.(iii)Although street tree density could partially compensate for the loss of large old trees,the protection of such trees is important because of their close associations with key ecosystem services,such as total carbon storage.To maximize the value of street trees in promoting urban sustainable development,trade-offs among multiple ecosystem services should be integrated within the overall planning process and adjustments of planting regimes.