Japanese Cypress Plantation Research Articles

Rainfall interception in temperate evergreen broadleaved forest and Japanese cypress plantation with abundant lower-layer vegetation in south-west Japan

ABSTRACT The interception of rainfall in conifer plantations has been intensively studied. However, research on broadleaved forests is limited, although the broadleaved forests dominate approximately half of forest area in Japan. Here, we compared the throughfall and stemflow of each vegetation layer to clarify interception in a naturally regenerated temperate evergreen broadleaved forest (lucidophyllous forest) and a Japanese cypress plantation over a three-year period. Both forests were approximately 100 years old and had abundant lower-layer vegetation. We found that approximately a quarter of rainfall was intercepted in both forests, although the half of that interception in the Japanese cypress plantation was owing to the abundant lower-layer vegetation. This indicated that the interception in the evergreen broadleaved forest was twice that of the Japanese cypress upper canopy. The well-developed layer structure in the evergreen broadleaved forest efficiently intercepted rainfall. From the point of view of water resource management, this study implies that both evergreen broadleaved forests and Japanese cypress plantations with abundant lower-layer vegetation can decrease the amount of water infiltrating soils.

Spatiotemporal Variations of Throughfall in an Unmanaged Japanese Cypress Plantation Laden with Dead Branches

Spatiotemporal Variations of Throughfall in an Unmanaged Japanese Cypress Plantation Laden with Dead Branches

Satellite remote sensing model for estimating canopy transpiration in cypress plantation using in situ sap flow observations and forest inventory

Transpiration (Et) in forests accounts for a significant fraction of evapotranspiration. However, because Et is influenced by meteorological factors and the physiological response of vegetation, developing an accurate model for predicting Et presents a challenge. In this study, we developed a model to estimate Et specific to cypress plantation forests using satellite remote sensing and sap flow data in Japanese cypress plantations composed of a single forest species. The contribution of Et to meteorological (Etbase) and plant physiology (Etleaf) was determined using the decoupling index along with the surface temperature. Using the Forest Inventory (FI), in which the extent of growth of each species, including cypress, was surveyed and Land Remote Sensing Satellite imagery of the FI range was obtained, an index of activity estimation for cypress trees was developed. The sapwood area, which significantly influences Et, was calculated from the tree age obtained from FI or diameter at breast height and incorporated into the model. The developed model exhibited a high correlation of r = 0.74–0.88 with the measured Et. The antecedent precipitation index (API), which represents the wetness of the land surface, can be used to evaluate the confidence level and correction coefficient (if needed) of model estimates. When corrected by API, Et could be estimated with even higher accuracy (r = 0.76–0.89). The model developed in this study considers the physiological responses of vegetation and plant species, and the same approach can be used to develop models to estimate Et for other tree species. Additionally, our model uses reflectance at wavelengths close to visible light and surface temperature and can, therefore, be readily applied to other remote sensing methods, such as unmanned aerial vehicles and airborne methods. The model developed in this study can be used with FI data to estimate Et by tree species to provide detailed and accurate estimates of Et.

Soil pH and divalent cations after clear-cutting on a Japanese cypress plantation

ABSTRACT Although Chamaecyparis obtusa reduces soil pH and cation levels, limited information is available regarding their alterations after clear-cutting. We examined the soil pH and base cations on the upslopes and downslopes of individual trees and stumps of C. obtusa at two distances (0.5 m and 1.0 m) and three depths (0–5, 5–10, and 10–30 cm) in intact- and cut-tree plots. The soil pH was higher in the cut-tree plot than in the intact-tree plot, indicating the recovery of soil pH after clear-cutting. The recovery was more evident in the surface soils (0–5 cm) of downslope areas (0.5 m) than in other soil depths, which implies that the recovery of soil pH was caused by the lack of H+ supply from stumps after clear-cutting. The results of H+ (in H2O: water-soluble and KCl: exchangeable) suggested a lack of soluble H+ in the cut-tree plot. Soil Ca2+ and Mg2+ levels in the surface soil (0–5 cm) were 1.86-fold and 1.93-fold higher in the cut-tree plot than in the intact-tree plot, respectively, implying that the recovery of divalent cations after clear-cutting was caused by a reduction in cation loss through cation exchange with H+ derived from the stemflow. Collectively, soil pH and divalent cations were recovered after clear-cutting because the stemflow had ceased.

Effects of tree mortality on the estimation of stemflow yield in a self‐thinning coniferous plantation

AbstractTree mortality by self‐thinning is an inevitable consequence of the long residence times of standing trees in unmanaged coniferous plantations. Stemflow (SF) is an important localized input of rainwater into the soil in forest ecosystems. However, little information is available on how tree mortality affects SF yields. We took weekly measurements from 16 trees in a 20 × 10 m plot containing 50 trees in a dense unmanaged Japanese cypress plantation from April to October 2017. These 16 trees were classified into two groups: standing‐live SF trees (n = 11, tree height [H]: 13.4 ± 1.1 m, DBH: 18.5 ± 3.8 cm, crown projection area [CPA]: 5.4 ± 0.8 m2, average ± standard deviation) and standing‐dead SF trees (n = 5, H: 7.9 ± 1.4 m, DBH: 10.0 ± 1.9 cm, CPA: 0.0 ± 0.0 m2). Because the smaller standing‐dead trees with no crown were all positioned under the canopy of standing‐live trees, the mean tree‐scale SF volume (SFVtree) of standing‐dead trees was approximately 10.3 times smaller than that of standing‐live trees. The much smaller SFVtree of standing‐dead trees was also explained by the basal area (3.5‐fold smaller) and the tree‐scale SF funnelling ratio (FRtree, 2.9‐fold smaller). SFVtree of standing‐dead trees was so small that the ratio of stand‐scale SF (SFstand) to gross rainfall (GR) (SFstand/GR) was similar regardless of whether standing‐dead trees were excluded or included (21.4% vs. 21.6%) in SFstand calculations, indicating that SFstand/GR could be reliably estimated using only standing‐live trees.

Ectomycorrhizal fungal communities in the boundary between secondary broad-leaved forests and Japanese cypress plantations

ABSTRACT Belowground ectomycorrhizal (ECM) fungal communities are affected by the dominant tree species of aboveground vegetation. We investigated ECM-fungal communities in the boundary between secondary broad-leaved forests dominated by ECM trees and cypress plantations consisting of arbuscular trees. ECM root tips were collected from soil cores and seedlings at a small scale within 20 m of the boundary. We used molecular analysis of internal transcribed spacer regions of rDNA to identify ECM-fungal species. Of the 104 molecular taxonomic units detected from soil cores and seedlings, the estimated ECM-fungal species richness in broad-leaved forests was higher than that in the cypress plantations. More than half of the ECM-fungal species detected in cypress plantations were shared with adjacent broad-leaved forests. In particular, Russulaceae and Thelephoraceae were dominant in broad-leaved forests and cypress plantations. However, low-frequency occurrence taxa in broad-leaved forests were mostly absent in cypress plantations, at a distance of more than 10 m from the boundary. ECM-fungal species associated with seedlings tended to differ between broad-leaved forests and cypress plantations. Furthermore, Cenococcum geophilum shared soil cores and seedlings in both stands. These results indicated that ECM-fungal communities in cypress plantations were affected by adjacent broad-leaved forests, and this effect likely involved distance from the boundary.

Soil erosion and overland flow in Japanese cypress plantations: spatio-temporal variations and a sampling strategy

ABSTRACT Many studies have focused on soil erosion in unmanaged Japanese cypress plantations because the sparse understory vegetation and litter covering the forest ground enhance soil erosion. In this study, soil erosion, litter, and overland flow measurements were conducted over 14 months to identify the spatio-temporal variation and examine the optimal sample size. Fifteen traps (each 0.25 m wide) were installed in line along the bottom of a 15-m-wide slope. Soil erosion and overland flow had large spatial variations as compared to litter. The temporal coefficient of variation of soil erosion and overland flow was highest during dry seasons, while smaller during wet seasons. The random sampling analysis showed that the rate of decrease in spatio-temporal variation became moderate as the sample size increased beyond six. This result indicated that the optimal sample size was five, the total width of which was equivalent to about 8% of the monitored slope width.

Modeling evapotranspiration changes with managing Japanese cedar and cypress plantations

Examining changes in evapotranspiration with forest management is one starting point for comprehensively understanding the impacts of forest management on water resources and forest resilience. This study builds on our previous work and develops a practical model that predicts changes in evapotranspiration with the management of Japanese cedar and cypress plantations. The model has distinct features that it requires only stem density, mean diameter at breast height, and basic meteorological data as inputs. This study first confirms that the model predicts annual evapotranspiration for cedar and cypress with relatively small errors (approximately 60 mm at the maximum). Next, this study shows that the model predicts changes in annual evapotranspiration with thinning and clearcutting of cedar and cypress with small errors (the mean absolute error of 86 mm). This study then demonstrates that coupling the model and yield tables enables prediction of annual evapotranspiration for different management scenarios and then the assessment of policy recommendations. Indeed, our model prediction suggests that the decrease in annual evapotranspiration with cedar and cypress aging is seemingly much smaller than that assumed in existing policy recommendations. Our model also suggests that the decrease in annual evapotranspiration with aging can more than triple by thinning at a rate of 50%, although this suggestion should be tested by future observation studies. The model is applicable only to Japanese cedar and cypress plantations under Japan’s meteorological conditions, but similar models for other mono-specific plantations can be developed. This study will thus inspire forest scientists to develop models that assist policymaking for other species in other areas.

Estimation of Bird Species that Utilize Japanese Cedar and Cypress Plantations with High Probability

Estimation of Bird Species that Utilize Japanese Cedar and Cypress Plantations with High Probability

Stemflow estimation models for Japanese cedar and cypress plantations using common forest inventory data

Although stemflow (SF) had been regarded as a small portion of the gross rainfall (GR), recent studies have revealed that, depending on the forest stand structure, the SF/GR ratio should not be neglected. This study derived SF/GR estimation models using common forest inventory data. A set of SF/GR ratio and forest inventory data (stand density (SD), total basal area (BA), mean diameter at breast height (DBH¯), mean tree height (H¯), canopy cover (CC), and leaf area index (LAI)) was collected from previous studies of Japanese cedar and cypress plantations. To further investigate the relation between SF/GR ratio and forest stand structures, we examined additional stand-structure variables (mean basal area (BA¯), mean stem surface area (SA¯), and total stem surface area (SA)) derived from the inventory data, and the stand-scale funneling ratio (FRstand) evaluating the efficiency of funneling rainwater. Among all the stand-structure variables, SD exclusively determined the SF/GR ratio, providing the best-fitting positive single linear regression equation as a density-based SF/GR model with a root mean square error (RMSE) of 2.4%. Although this model is useful for practical forest water management because it requires only SD which is the most basic forest inventory data, it has a weak point in meticulous forest water management because it cannot reflect the effect of tree growth on SF/GR ratio. Thus, we developed a size-based SF/GR model (RMSE = 2.0%) based on the strong relationship between the FRstand and DBH¯. This model is applicable to meticulous forest water management because it reflects the effects of not only SD but also tree growth by DBH on SF/GR ratio. These models derived from the common forest inventory data are potentially applicable to the evaluation and control of SF in forest water management.

Relationship between stand structures and rainfall partitioning in dense unmanaged Japanese cypress plantations

Relationship between stand structures and rainfall partitioning in dense unmanaged Japanese cypress plantations

Factors influencing the erosivity indices of raindrops in Japanese cypress plantations

Severe soil erosion has been reported in monoculture forests without understory vegetation and litter on the floor. To clarify the factors that affect raindrop erosivity in monoculture forests, we measured raindrop erosivity in Japanese cypress (Chamaecyparis obtuse Endl.) plantations using splash cups. Splash cups can possibly measure raindrop erosivity from loss of sand (LoS). We first examined the relation between raindrop erosivity and LoS under natural rainfall in an open space. LoS was strongly correlated with raindrop erosivity factors, such as the kinetic energy and momentum multiplied by the drop diameter. We then observed LoS using 12–16 splash cups in seven plots with different canopy structures in Japanese cypress plantations. LoS at each point was compared with the amount of throughfall (Tf) and canopy structure factors, such as canopy openness (Co) and distance to the closest branch (Br). The relation between Tf and LoS was similar among the plots, except in one plot where the canopy and crown-base heights were the smallest. Our results imply that Tf is a dominant factor determining raindrop erosivity when canopy and crown-base heights are more than the threshold values (15.2 m for the canopy height and 10.5 m for the crown-base height in our forests). In plot 1, LoS was correlated with not only Tf but also Br. When analyzing all the data together using generalized linear models, LoS was affected by Br besides Tf. In monoculture forests with a high canopy, Tf measurements enable us to estimate raindrop erosivity. In monoculture forests with a low canopy, Br (or the canopy height) should also be considered when estimating the erosivity of raindrops.

Effect of canopy openness and meteorological factors on spatial variability of throughfall isotopic composition in a Japanese cypress plantation

AbstractSpatial variability of throughfall (TF) isotopic composition, used as tracer input, influences isotope hydrological applications in forested watersheds. Notwithstanding, identification of the dominant canopy factors and processes that affect the patterns of TF isotopic variability remains ambiguous. Here, we examined the spatio‐temporal variability of TF isotopic composition in a Japanese cypress plantation, in which intensive strip thinning was performed and investigated whether canopy structure at a fine resolution of canopy effect analysis is related to TF isotopic composition and how this is affected by meteorological factors. Canopy openness, as an index of canopy structure, was calculated from hemispherical photographs at different zenith angles. TF samples were collected in a 10 × 10 m experimental plot in both pre‐thinning (from July to November 2010) and post‐thinning (from May 2012 to March 2013) periods. Our results show that thinning resulted in a smaller alteration of input δ18O of gross precipitation, whereas the changes in deuterium excess varied in both directions. Despite the temporal stability of spatial patterns in TF amount, the spatial variability of TF isotopic composition was not temporally stable in both pre‐ and post‐thinning periods. Additionally, after thinning, the isotopic composition of TF was best related to canopy openness calculated at the zenith angle of 7°, exhibiting three different relationships, that is, significantly negative, significantly positive, and nonsignificant. Changes in meteorological factors (wind speed, rainfall intensity, and temperature) were found to affect the relationships between TF δ18O and canopy openness. The observed shifts in the relationships reveal different dominant factors (partial evaporation and the selection), and canopy water flowpaths control such differences. This study provides useful insights into the spatial variability of TF isotopic composition and improves our understanding of the physical processes of interception through canopy passage.

Estimation of throughfall with changing stand structures for Japanese cypress and cedar plantations

Throughfall (TF) is a critical component of the hydrological and biogeochemical cycles and is greatly influenced by stand structures in forested watersheds. Previous studies have examined the relationships between TF and stand structures for different species and regions. However, there remains acknowledged difficulty in estimation of TF with changing stand structures due to forest management (e.g., thinning) for specific species and regions. This study conducted intensive thinning with 43–50% stem removal at seven experimental plots with various structures (e.g., stand density, canopy cover and basal area) across Japan that were covered by Japanese cypress (Chamaecyparis obtusa Endl.) and cedar (Cryptomeria japonica D. Don) plantations. TF was measured by a set of 20 tipping-bucket rain gauges placed in a lattice-like pattern within the plots before and after thinning. Results showed that during the study periods, thinning caused an increase in the mean TF rate from 63.2±7.0% to 75.4±6.0%. The TF rate was significantly negatively correlated with stand density, canopy cover, and basal area on a stand scale. Additionally, the slope (aTF) of event-based linear TF-Pg (gross rainfall) equation was significantly higher in post-thinning (0.782±0.077) than that in pre-thinning (0.663±0.078), whereas it’s intercept (bTF) showed no significant difference (−0.707±0.810mm in pre-thinning and −0.441±0.607mm in post-thinning). The aTF significantly decreased with increasing stand density and canopy cover, whereas the bTF was not significantly correlated with any forest-structure variables. Further, the TF rate and aTF were estimated, respectively, by their related stand-structural variables in multiple regression models with high determination coefficients and moderate relative errors. The bTF was assumed to be a constant and its mean value obtained from all the experimental plots in each (pre- and post-thinning) period. Thus, the models of stand-scale TF rate and event-based TF amount were developed with input of commonly forest inventories. These models were validated by using the dataset of this study and earlier publications for Japanese cedar and cypress plantations, and showed good fit between the estimated and measured values. These models are practical tools that can be readily used for assessing the changes in TF with changing stand structures at both stand and event-based scales, and have also potential implications in evaluating the spatial TF patterns at catchment scale and exploiting similar models in other species and regions.

Change in evapotranspiration partitioning after thinning in a Japanese cypress plantation

Thinning resulted in evapotranspiration decrease and caused the relative contributions of each component to evapotranspiration to become very close. To increase the understanding of forest management to control water cycles, we examined the effect of 50% strip thinning on evapotranspiration (ET) and its partitioning into canopy interception (E i), tree transpiration (E t), and forest floor evaporation (E f) in a Japanese cypress (Chamaecyparis obtusa Endl.) plantation. Intensive measurements were employed to monitor each component of ET during the pre- and post-thinning periods. The results showed the annual E t was the dominant component of ET followed by E i, whereas E f was the smallest component in both periods. Thinning has significant impact on the process of ET partitioning. In such that it decreased from 42.3 to 33.7% in E i/ET and from 45.0 to 34.9% in E t/ET, and increased from 12.7 to 31.4% in E f/ET on an annual scale. The relative contributions of each ET component to the whole ET became more or less the same after thinning. Additionally, the monthly E i/P g had relative stable values in both pre- and post-thinning periods, contributing significantly to the ET/P g during heavy rainfall conditions. After thinning, ET decreased by 21.4% from 629.3 to 494.8 mm during the growing season and by 20.4% from 979.8 to 780.1 mm at the annual scale, demonstrating that thinning results in an increase in water availability in the forested watershed. This study can improve the understanding of forest water budget in response to thinning and aid in development of appropriate forest management practices accordingly.

Effects of sika deer browsing on soil mesofauna in a thinned Japanese cypress plantation

ABSTRACTWe examined the indirect effects of sika deer (Cervus nippon) overabundance on soil mesofauna in a thinned plantation. We compared the understory vegetation, environmental conditions at the forest floor, and soil mesofauna inside and outside of a fenced area established at a plantation of Japanese cypress in central Japan about 6 years after thinning. Deer browsing had reduced the volume of understory plants outside the fence; this tended to not cause a reduction in the litter mass and an increase in the soil bulk density, but caused an increase in the relative photosynthetic photon flux density reaching the forest floor. As a result, the relative humidity at the forest floor was lower outside the fence than inside. The abundances of detritivores and fungivores and predators in the soil mesofauna declined significantly in areas with deer. This could be due to desiccation in the litter layer inhabited by many detritivores and fungivores and predators that are sensitive to changes in moisture conditions. Thus, deer browsing had a negative effect on the soil mesofauna as well as on the aboveground fauna in the understory vegetation.

Wind profiles and mechanical resistance of uprooted trees in a Japanese cypress (Chamaecyparis obtusa) plantation slightly damaged by Typhoon Melor 0918 at Kamiatago Experimental Forest, Tenryu, Japan : Validity of mechanistic models for wind damage risks

Wind profiles and mechanical resistance of uprooted trees in a Japanese cypress (Chamaecyparis obtusa) plantation slightly damaged by Typhoon Melor 0918 at Kamiatago Experimental Forest, Tenryu, Japan : Validity of mechanistic models for wind damage risks

Soil and the foliage nutrient status following soil amendment applications in a Japanese cypress (Chamaecyparis obtusa Endlicher) plantation

ABSTRACTThe aim of this study was to evaluate the response of soil amendment applications on soil and the foliage nutrient status of a Japanese cypress (Chamaecyparis obtusa Endlicher) plantation established following clear-cutting in a pine-wilt-disease (PWD)-disturbed forest. We established four soil amendment treatments [(compound fertilizer (CF), compound fertilizer + biochar (CFB), compound fertilizer + sawdust (CFS) and a non-treated control treatment] in an 8-year-old Japanese cypress plantation. Soil organic carbon (C) and total nitrogen (N) were not significantly different (P > 0.05) between the soil amendment treatments and the control treatments, whereas extractable phosphorus (P), NH4+, K+, and Mg2+ concentrations were significantly affected by the addition of biochar in CF. The mean soil CO2 efflux rates during the study period were the highest in CFB (0.79 g CO2 m−2 h−1), followed by CFS (0.71 g CO2 m−2 h−1), CF (0.62 g CO2 m−2 h−1), and the control (0.46 g CO2 m−2 h−1) treatments. Foliar N and P concentrations were significantly higher in the CFB than in the control treatments. The results suggest that the addition of biochar in CF can enhance extractable soil nutrients and foliar N and P conditions of Japanese cypress established in a PWD-disturbed forest.

阿蘇地域のヒノキ高齢低密度人工林における遮断率の観測

阿蘇地域のヒノキ高齢低密度人工林における遮断率の観測

Effect of stand structure and climatic factors on throughfall isotopic composition in a Japanese cypress plantation

Effect of stand structure and climatic factors on throughfall isotopic composition in a Japanese cypress plantation