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Rainfall interception and other hydrologic processes affected by the forest litter layer are usually related to litter characteristics and rainfall conditions, with limited studies that consider the influence of slope. To simulate the hydrological functions of the litter layer at different slope gradients, artificial rainfall experiments were conducted at four rainfall intensities (from 30 to 120 mm hr−1) in horizontal and inclined trays (with the slope of 0°, 10°, 20° and 30°) with litter of Pinus tabuliformis or Quercus variabilis. The results indicated that (1) the dynamic process of litter interception had 3 phases: a rapid intercepted phase within the first 5 min, a moderate intercepted phase and a post-rainfall drainage phase; (2) the maximum interception storage (Cmax) and the minimum interception storage (Cmin) of Q. variabilis were larger than those of P. tabuliformis; (3) Cmax and Cmin were correlated with slope for both types of litter, whereas only Cmax was correlated with rainfall intensity; and (4) lateral flow amount significantly increased with both slope gradient and rainfall intensity only for Quercus variabilis, whereas drainage volume showed significant correlation with rainfall intensity. Moreover, the ratio of lateral runoff and drainage was affected by slope gradient whereas percentage of litter interception had a good relationship with rainfall intensity, rather than slope, with litter interception and drainage contributing the smallest and the largest proportions, respectively. Overall, the results demonstrate the effect of rainfall and slope factors on hydrological processes in the forest litter layer.

The aim of this study was to quantify street tree population dynamics in the city of Claremont, CA. A repeated measures survey (2000 and 2014) based on a stratified random sampling approach across size classes and for the most abundant 21 species was analyzed to calculate removal, growth, and replacement planting rates. Demographic rates were estimated using a hierarchical Bayesian framework. The community-level (all species) median growth rate was 1.41% per year (95% CI: 1.21–1.65%) with Pinus brutia and Pistacia chinensis growing significantly faster than the community-level median. The community-level median removal rate was 1.03% per year (95% CI: 0.66–1.68%), with no significant differences between species and the community-level medium. Once removed, only 7.2% (95% CI: 4.4–12.9%) were replaced annually. Presence of overhead utility lines influenced tree removal rates while age, diameter-at-breast-height, and prior tree condition influenced tree growth. Overall live aboveground biomass in sampled sites was 713.29 Mg in 2000 and increased to 877.36 Mg by 2014. Biomass gain from growth outweighed loss from removals nearly three-fold; replacement contributed 0.5% of the total biomass gain. We conclude that to increase the resilience of the street tree population will require 1) an increase in percent of full stocking or biomass stock and 2) a shift in the species palette to favor species less vulnerable to pests and expected disturbance from climate change and 3) ongoing monitoring to detect departures from baseline demographic rates.

Rainfall interception by a tree's crown is one of the most important hydrological processes in an ecosystem, yet the mechanisms of interception are not well understood. A process-based experiment was conducted under five simulated rainfall intensities (from 10 to 150 mm h−1) to directly quantify tree crown interception and examine the effect of rainfall traits and crown structure characteristics on interception for broadleaf (Platycladus orientalis, Pinus tabulaeformis) and needle tree species (Quercus variabilis, Acer truncatum). Results indicated that (1) the interception process was composed of three phases, a rapid increase phase which accounted for approximately 90% of the maximum interception storage (Cmax), a relatively-stable phase, and a post-rainfall drainage phase in which 40% (±16%) of Cmax drained off to reach the minimum interception storage (Cmin); (2) Cmax and Cmin were only correlated with rainfall intensity for P. tabulaeformis; (3) Cmax and Cmin were correlated with both leaf traits (i.e., leaf area, leaf biomass, leaf morphology) and branch traits (i.e., branch density, branch count, branch length, woody surface area, and woody biomass), and the best predictors of Cmax and Cmin were biomass-related parameters; and (4) The needle species P. orientalis had the greatest Cmax, while the largest Cmin was observed in the broadleaf species A. truncatum. Our findings demonstrate the complexity of the interception process and tree characteristics may be more important in controlling interception than rainfall characteristics.

An experiment was conducted to concentrate on the rainfall interception process of individual trees for four common species in Beijing, China, which included needle species (Platycladus orientalis and Pinus tabulaeformis) and broadleaf species (Quercus variabilis and Acer truncatum). Two types of interception storages, the maximum (Cmax) and the minimum interception storage (Cmin), were examined at four simulated rainfall intensities (from 11.7 to 78.5 mm h−1). Results showed that an average of 91% of Cmax for all the species was intercepted during the first 10 minutes of rainfall, while 45% of Cmax drained off after rainfall cessation. Leaf area index (LAI) and leaf area (LA) were significantly correlated (p < 0.05) with Cmax and Cmin, while such significant correlations were not found between rainfall intensity and Cmax and Cmin. Average Cmax and Cmin across all the species corresponded to 3 and 1% of gross rainfall. Mean Cmax and Cmin of the needle species were 3.0 and 1.8 times larger than that for the broadleaf ones. Results revealed that interception was a dynamic process which encompassed three phases. In addition, LAI and LA were valid predictors of interception in small trees, and deserve further test in forest stands.

The aim of this work was to assess Scots pine (Pinus sylvestris L.) growth response and potential productivity on various reclaimed mine soils (RMS) developed on dominant parent rock in Poland (Central Europe). The study was conducted on four afforested post-mining sites after lignite, hard coal, sand and sulphur mining extraction. Site index (SI) was modeled as a function of the top height of a pine tree stand at a certain age and physico-chemical and biological properties of RMS. Field measurements were taken in tree stands ranging from 12 to 30 years of age. A total of 42 site trees (1–2 dominant trees on each plot) representing top height (H500) were cut and the age and height increment of each tree was estimated on the basis of distance between branch verticils. Soil samples were collected at 0–8, 8–50 and 50–110 cm depth and the following parameters were determined: soil texture, pH, total exchangeable bases TEB, cations exchangeable capacity, soil organic carbon (SOC), nutrient content (N, Ca, Mg, K, Na, P) and microbial properties (dehydrogenase activity; DHG). Statistical models were developed describing relationships between tree growth as expressed by SI and key mine soil properties. The best model explained a relatively large part (>60 %) of SI variability. In this model, the most influential RMS properties were: clay sized (

This work deals with bioaccumulation of Zn, Pb, Cu and Cd in foliage of Scots pine, grown on mine soils. Regression models were used to describe relationships between pine elements bioavailability and biological (dehydrogenase activity) and physico-chemical properties of mine soils developed at different parental rocks. Concentration of trace elements in post-mine ecosystems did not differ from data for Scots pine on natural sites. We conclude that, in this part of Europe in afforested areas affected by hard coal, sand, lignite and sulphur mining, there is no risk of trace element concentrations in mine soils. An exception was in the case of Cd in soils on sand quarry and hard coal spoil heap located in the Upper Silesia region, which was more due to industrial pressure and pollutant deposition than the original Cd concentration in parental rocks.