Age-Related Changes in Water and Nitrogen Utilization in Crop Trees and Understory Vegetation in a Hinoki Cypress Plantation Forest in Kochi City, Southern Japan

Inagaki, Yoshiyuki; Miyamoto, Kazuki; Sakai, Atsushi

doi:10.3390/nitrogen3020017

Cited by 3 publications

(1 citation statement)

References 53 publications

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“…A study in Sweden suggested that the aboveground biomass increases after reducing clear cutting in the area, thus lowering the nitrogen loss from stream water (Lucas et al, 2016). The nitrogen concentration in the leaf litter of a hinoki cypress planation decreases with increasing severity of competition with understory vegetation (Inagaki et al, 2022b). In another study, loss of understory vegetation by deer browsing increased the NO 3 loss from stream water (Chiwa, 2021).…”

Section: Discussionmentioning

confidence: 97%

Effects of climate and acidic deposition on inter-annual variations of stream water chemistry in forested watersheds in the Shimanto River Basin, southern Japan

Inagaki

Sakai

Shinomiya

et al. 2023

Preprint

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Although the amount of acidic deposition has recently decreased in Japan, acid deposition has deteriorated some forest ecosystems during the past few decades. We investigated the yearly variations in stream water chemistry for more than 20 years in two areas (Yusuhara and Taisho) in the Shmanto River Basin, southern Japan, where the effects of acidic deposition are considered to be modest. Stream water samples were collected monthly from three forest watersheds selected at each site. The annual means of the stream chemistry were predicted by multiple regression analysis. The sunlight hours were positively related with the potassium, magnesium, calcium, nitrate, sulfate, and bicarbonate concentrations in stream water. The results suggest that long sunlight hours boost the photosynthetic activities, thus promoting soil respiration and decomposition of soil organic matter; moreover, a higher carbonic acid concentration in the soil solution promotes cation weathering and carbonic acid dissociation to bicarbonate. The ammonium, nitrate, and sulfate concentrations in the bulk precipitation have decreased at Yusuhara and the sodium, magnesium, calcium, chloride, nitrate, and sulfate concentrations in the stream water have decreased in both areas. The nitrate and sulfate concentrations apparently responded to the decreasing input of acidic deposition. Given the decreasing trends in magnesium and calcium concentration with no change in bicarbonate concentration, we inferred that previous inputs of acidic deposition enhanced the rate of rock weathering.

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Section: Discussionmentioning

confidence: 97%

Effects of climate and acidic deposition on inter-annual variations of stream water chemistry in forested watersheds in the Shimanto River Basin, southern Japan

Inagaki

Sakai

Shinomiya

et al. 2023

Preprint

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Stand characteristics regulate forest water use efficiency in the Three-North Shelterbelt Forest Program region of China

Pang,

Xu,

Zhang

et al. 2024

Environ. Res. Lett.

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The Three-North Shelter Forest Program (TNSFP) of China, one of the largest forestry ecological projects, serves as a nature-based solution to addressing ecological, social, and economic challenges and issues. This program, mainly situated in arid and semi-arid regions, critically focuses on improving water use efficiency (WUE) - maximizing carbon sequestration per unit of water consumed - as a key strategy for optimizing water resource utilization and ensuring the long-term success of vegetation restoration efforts. However, the regulatory mechanisms of forest WUE in this region remain unclear. Here, we adopted an interpretative machine-learning method to investigate the influence of main environmental elements, topographical conditions, and stand characteristics on forest WUE in the TNSFP region from 2001 to 2022 based on remote sensing products, ground monitoring data, and forest inventory data. Our study identified soil moisture (SM) as the primary factor influencing forest WUE across the TNSFP region, with higher SM levels generally leading to improved WUE in forests. However, stand characteristics strongly mediated their relationship. Specifically, forest WUE initially increases against forest density before peaking at about 1000 trees hm–2 for needle-leaved forests and 800 trees hm–2 for broad-leaved forests, respectively, then gradually declining due to water competition. When SM is relatively adequate, moderate thinning could significantly enhance forest WUE. Furthermore, implementing management strategies to improve WUE is crucial as needle-leaved forests mature. This study emphasizes the significant impacts of stand characteristics on forest WUE in the TNSFP region, offering essential insights for optimizing water resource management in managed forests across arid and semi-arid regions.

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Effects of climate and acidic deposition on interannual variations of stream water chemistry in forested watersheds in the Shimanto River Basin, southern Japan

Inagaki,

Sakai,

Shinomiya

et al. 2024

Ecological Research

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Although the amount of acidic deposition has recently decreased in Japan, it has still deteriorated some forest ecosystems during the past several decades. Moreover, recent climate changes can affect stream water chemistry. We investigated the temporal trend and effects of climate conditions on stream water chemistry for more than 20 years in two areas (Yusuhara and Taisho) in the Shmanto River Basin, southern Japan, where the effects of acidic deposition are considered to be modest. Stream water samples were collected monthly from three forest watersheds selected at each site. The annual means of the stream chemistry were predicted by multiple regression analysis. The ammonium, nitrate, and sulfate concentrations in the bulk precipitation have decreased at Yusuhara, and the sodium, magnesium, calcium, chloride, nitrate, and sulfate concentrations in the stream water have decreased in both areas. The nitrate and sulfate concentrations apparently responded to the decreasing input of acidic deposition. The sunlight hours were positively related with the potassium, magnesium, calcium, nitrate, sulfate, and bicarbonate concentrations in stream water. The results suggest that long sunlight hours boost the photosynthetic activities, thus promoting soil respiration and decomposition of soil organic matter. Moreover, a higher carbonic acid concentration in the soil solution promotes cation weathering and carbonic acid dissociation to bicarbonate. Given the decreasing trends in magnesium and calcium concentration with no change in bicarbonate concentration, we inferred that previousinputs of acidic deposition enhanced the rate of rock weathering.

show abstract

Age-Related Changes in Water and Nitrogen Utilization in Crop Trees and Understory Vegetation in a Hinoki Cypress Plantation Forest in Kochi City, Southern Japan

Cited by 3 publications

References 53 publications

Effects of climate and acidic deposition on inter-annual variations of stream water chemistry in forested watersheds in the Shimanto River Basin, southern Japan

Effects of climate and acidic deposition on inter-annual variations of stream water chemistry in forested watersheds in the Shimanto River Basin, southern Japan

Stand characteristics regulate forest water use efficiency in the Three-North Shelterbelt Forest Program region of China

Effects of climate and acidic deposition on interannual variations of stream water chemistry in forested watersheds in the Shimanto River Basin, southern Japan

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