Next Article in Journal
Effects of Trunk Distance and Rainfall on Throughfall and Associated Chemical Alterations within a Subtropical Deciduous Forest
Next Article in Special Issue
Quantifying the Effects of Root and Soil Properties on Soil Detachment Capacity in Agricultural Land Use of Southern China
Previous Article in Journal
Identifying Socioeconomic Determinants of Households’ Forest Dependence in the Rubi-Tele Hunting Domain, DR Congo: A Logistic Regression Analysis
Previous Article in Special Issue
RETRACTED: Evaluation of Soil Pollution by Potential Toxic Elements in Cultivated Land in the Poyang Lake Region Based on an Improved Matter–Element Extension Model
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Forests
Volume 13
Issue 10
10.3390/f13101708
forests-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Effects of Different Forest Gap Ages on Soil Physical Properties and Stoichiometric Characteristics in Cryptomeria japonica plantations (L.f.) D.Don, 1839

by
Tingqi Xiao
,
Chen Wang
,
Xi Yuan
,
Lingjian Tao
,
Peng Li
,
Wenping Deng
and
Yuanqiu Liu
*
Lushan National Observation and Research Station of Chinese Forest Ecosystem, Jiangxi Provincial Key Laboratory of Silviculture, College of Forestry, Jiangxi Agricultural University, Nanchang 330045, China
*
Author to whom correspondence should be addressed.
Forests 2022, 13(10), 1708; https://0-doi-org.brum.beds.ac.uk/10.3390/f13101708
Submission received: 17 September 2022 / Revised: 11 October 2022 / Accepted: 14 October 2022 / Published: 17 October 2022
(This article belongs to the Special Issue Assessments and Restoration Technique of Forest Land Development in Hilly Areas)
Browse Figures
Versions Notes

Abstract

:
In this study, the evergreen plant Cryptomeria japonica (L.f.) D.Don, 1839 forest gap in the subtropical region of China were taken as the research object. The effects of different forest gap ages (<10 years, 10–20 years, >20 years) on soil physical properties and stoichiometric characteristics were analyzed in Lushan Mountain, China. With the increase of forest gap ages, the physical properties of soil surface layer in forest gap were improved, and the water holding capacity of soil was enhanced. The capillary porosity and total porosity of soil increased significantly, and the soil bulk density of 10–20 cm soil layer decreased. The increase of forest gap recovery years is beneficial to the increase of large particle size soil aggregates, and the increase of large particle size aggregates has a good effect on improving soil structure. The contents of carbon (C), nitrogen (N), and phosphorus (P) in soil showed an overall increasing trend with the increase of forest gap age and were significantly higher than those of Cryptomeria japonica pure forest (p < 0.05). The nutrient content of forest gap in 10–20 years was the highest, and the nutrient content of 0–10 cm soil layer was generally higher than that of 0–20 cm soil layer. The C:P and N:P in the soil showed an overall decreasing trend, while C:N was significantly smaller than other age gaps in 10–20 years. The results showed that soil physical properties and stoichiometric characteristics were improved with the increase of forest gap ages.

1. Introduction

Forest gap mainly refers to the death of old trees in the forest community or the death of dominant tree species in the mature stage due to accidental factors (such as drought, fire, etc.), thus causing gaps in the canopy [1]. As a medium- and small-scale disturbance, forest gap affects species composition, structure, and succession direction of forest [2]. As an important driving force for forest regeneration and environmental improvement, forest gap plays an important role in dynamic succession and ecological function optimization of forest ecosystem [3]. Forest gap is an important driving force for forest natural regeneration and an important channel for regulating vegetation recombination in plantations. It plays an important role in vegetation succession and nutrient cycling in forest ecosystems [4]. On the other hand, the formation of canopy gap can affect the microenvironment under canopy, the invasion and colonization of plants, and the regeneration of understory vegetation, and then change the stand structure, which may exert a strong effect on the ecological stoichiometric characteristics of canopy gap regeneration plants [5]. Compared with closed forest, the formation of forest gap changes the water and heat dynamics and decomposer community structure in the forest, which can affect the nutrient utilization and turnover efficiency of understory vegetation (such as litter decomposition), and then deeply affect the distribution pattern of soil nutrients [6].
Water conservation is an important part of forest ecosystem service function [7], mainly through the three levels of canopy, ground cover, and soil, in which forest soil is the main body of water conservation [8]. Soil water holding capacity is an important indicator of water conservation in terrestrial ecosystems and plays a key role in surface processes and water cycle [9]. Soil water holding capacity is mainly affected by soil physical and chemical properties, such as soil bulk density, porosity, soil aggregate size distribution, soil structure and organic matter, etc. [10]. Among them, soil organic matter and soil water holding capacity have a strong correlation [11]. Accumulation of soil organic matter can improve water binding and water retention capacity by changing soil structure, or by changing soil porosity, thereby increasing soil water holding capacity, especially in the surface soil [12,13,14].
Soil is an important part of terrestrial ecosystem and the main source of nutrients for the growth and development of forest vegetation [15]. Carbon (C), nitrogen (N), and phosphorus (P) in soil are essential nutrients for the growth of forest plants, which directly affect the growth and development of plants, the activity of soil microorganisms, and the nutrient cycle of soil [16]. Their ratios are considered to be important indicators of ecosystem structure and function [17]. Soil stoichiometry is a science that studies the balance and interaction of various chemical elements (mainly C, N, and P) in the soil [18]. It is believed that the ratio of element composition (C, N, and P) in the soil is stable, and the change of any element will change this ratio, which can be used to study the nutrient cycle in the soil ecosystem and determine its nutrient limiting factor [19,20]. At present, chemometrics theory has been widely used in plant tissues, forest communities, plant response to the environment, soil nutrient cycling, and dynamic changes of microbial elements [21,22]. Soil stoichiometry is often used to reflect the relationship between nutrients in the soil and the availability of nutrients, revealing soil nutrient limitation, nutrient cycling, and balance mechanisms [23,24]. Therefore, a comprehensive study of terrestrial soil nutrient content and its stoichiometric ratio can provide a theoretical basis for soil restoration of terrestrial ecosystems [25,26].
Cryptomeria japonica (L.f.) D.Don, 1839 is an evergreen coniferous tree species of Cupressaceae [27]. It is an important part of different forest types in Lushan Mountain and one of the main afforestation tree species with high ecological and economic value [28]. At the beginning of the 20th century, Lushan Mountain in Jiangxi Province, China, was successfully introduced from Japan and subsequently planted in various parts of China [29]. Cryptomoria japonica is mainly distributed in the area above the altitude of 700 m in Lushan Mountain. It is the main afforestation tree species in the area and plays an important role in water conservation, atmospheric environment purification, forest recreation, and other ecological functions [30]. As Cryptomoria japonica tree age is generally larger, stand resistance decreased over the years often due to freezing rain and snow, whilst typhoons and other natural disasters led to tree tipping or even lodging phenomenon, and formed a forest gap. At present, the research on forest gap mainly focuses on the characteristics of forest gap and its environmental factors. The research on the spatial heterogeneity of forest gap mainly focuses on light, temperature, air relative humidity, and soil nutrients [31,32]. However, there are few studies on the physical properties and stoichiometric characteristics of soil caused by the interference gradient of forest gap formation at different ages, which limits the understanding of the mechanism of forest gap soil change to a certain extent. Ecological stoichiometric study provides an important indicator for forest soil nutrient limitation or nutrient cycling. At present, there are few reports on soil stoichiometric characteristics of forest gap. In particular, the relationship between soil physical properties and soil nutrient stoichiometric ratio of forest gaps with different ages is not clear. This study can help to understand the soil nutrient limitation of different forest gap ages. The significance of this study is to reveal the effects of different forest gap ages on soil physical and chemical properties and stoichiometric characteristics.

2. Materials and Methods

2.1. Research Area

This experiment was conducted in Lushan National Nature Reserve, Jiujiang City, Jiangxi Province, China (Figure 1) (115°52′–116°06′ E, 29°25′–29°41′ N), with an area of about 30.2 km2. It belongs to a typical subtropical monsoon climate with an average annual temperature of 11.6 °C and an average annual precipitation of 2070 mm. Lushan Mountain has frost up to 150 days, and has foggy days 191 days, a year. Lushan Mountain is adjacent to the Yangtze River to the north and the Poyang Lake to the east. The complex topography and special climatic characteristics form a variety of habitats and have rich biodiversity. Among them, the plantation is dominated by coniferous forests. The most representative tree species are Cryptomeria japonica, Pinus taiwanensis, Cunninghamia lanceolata, etc. The soil types of Lushan Mountain are various, which are mountain brown soil, yellow soil, or red soil. The soil layer is barren, and the soil is rocky. Lushan Mountain’s highest altitude is 1446 m, with a unique geographical location and climatic conditions. Early-November to March is the snowfall period. Cryptomeria japonica often suffered snow and ice damage. When damaged after interference, Cryptomeria japonica forest progresses into a natural regeneration recovery.

2.2. Experimental Design

According to the previous survey results, through field investigation, three types of forest gaps of different ages were selected: <10 years, 10–20 years, and >20 years. Three plots were selected as replicates for each gap type, and Cryptomeria japonica pure forest with the same stand age and similar site conditions outside the gap was selected as the control (CK). According to the diagonal line of the plot, three points (upper slope, middle slope, and lower slope) were selected and divided into 0–10 cm and 10–20 cm depths to collect soil. The collected soil samples are divided into two parts: one part is to collect undisturbed soil by ring knife method to determine soil physical properties; the other part collected scattered soil and measured the soil particle size distribution and soil nutrients after drying. Gravel, litter, and other debris was removed from soil samples. The soil’s natural water content was measured by drying method, and the soil bulk density, porosity characteristics (total porosity, capillary porosity, and non-capillary porosity), and water holding capacity characteristics (maximum water holding capacity, capillary water holding capacity, and field water holding capacity) were measured by cutting ring method. The collected bulk soil was divided into six fractions by soil aggregate analyzer after natural drying, namely >2 mm, 1–2 mm, 0.5–1 mm, 0.25–0.5 mm, 0.106–0.25 mm, and <0.106 mm. The contents of total nitrogen (TN) and total phosphorus (TP) in soil were determined by Smartchem Discrete Auto Analyzer, and the content of soil organic carbon (SOC) was determined by potassium dichromate oxidation-external heating method.

2.3. Statistical Analyses

We calculated the soil bulk density, porosity, water holding capacity, and nutrient content (C, N, and P) of each forest gap age. IBM SPSS 25.0 software was used to analyze the data. One-way ANOVA and Tukey multiple comparison (α = 0.05) were used to analyze the effects of different forest gap ages on soil bulk density, porosity characteristics (total porosity, capillary porosity, and non-capillary porosity), water holding capacity characteristics (maximum water holding capacity, capillary water holding capacity, and field water holding capacity), nutrient content (C, N, and P), and stoichiometric characteristics.

3. Results

3.1. Soil Water Holding Capacity Characteristics in Forest Gap of Different Ages

The soil maximum water holding capacity, field water holding capacity, and capillary water holding capacity of Cryptomeria japonica pure forest after the formation of forest gap decreased significantly in <10 years (p < 0.05) (Table 1) but increased significantly with the increase of forest gap ages (p < 0.05). In the 0–10 cm soil layer, the maximum water holding capacity, field water holding capacity, and capillary water holding capacity of >20 years forest gap soil increased by 36.0%, 24.3%, and 28.2% compared with <10 years, respectively. In 10–20 cm soil layer, the maximum water holding capacity, field water holding capacity, and capillary water holding capacity of <10 years forest gap soil decreased by 17.8%, 16.5% and 20.4% compared with >20 years, respectively. The results showed that the increase of Cryptomeria japonica forest gap ages could improve the physical properties of surface soil moisture and enhance soil water holding capacity.

3.2. Soil Bulk Density and Porosity Characteristics in Forest Gap of Different Ages

In the 0–10 cm soil layer, the soil bulk density of 10–20 years forest gap increased by 12.0% compared with pure forests (Table 2), and the soil bulk density of >20 years forest gap was 9.5% lower than 10–20 years. In the 10–20 cm soil layer, the soil bulk density of >20 years forest gap decreased by 8.2% compared with pure forest. In the 0–10 cm soil layer, the capillary porosity, non-capillary porosity, and total porosity of >20 years forest gap increased by 7.8%, 41.2%, and 11.7% compared with the pure forest, respectively. This study showed that the capillary porosity and total porosity of soil increased significantly with the increase of forest gap restoration years, the soil bulk density of 10–20 cm soil layer showed a decreasing trend, and the soil of >20 years forest gap showed a looser structure, which improved the soil structure compared with Cryptomeria japonica pure forest.

3.3. Soil Aggregate Particle Size Distribution in Forest Gap of Different Ages

Aggregates of >2 mm and 1–2 mm were dominant in 0–10 cm and 10–20 cm soil layers in Cryptomeria japonica pure forest and forest gap of different ages (Table 3). Soil aggregates of 1–2 mm, 0.5–1 mm, and 0.25–0.5 mm in 0–10 cm and 10–20 cm soil layers showed an overall increasing trend with the increase of forest gap restoration years (p < 0.05), and in 10–20 cm soil layer, aggregates of 1–2 mm and 0.5–1 mm had significant differences in different restoration ages (p < 0.05), which showed that >20 years forest gap was significantly larger than <10 years forest gap and Cryptomeria japonica pure forest (p < 0.05). The results of this study showed that the increase of forest gap restoration years was beneficial to the increase of the content of large particle soil aggregates.

3.4. Soil Nutrient Characteristics in Forest Gap of Different Ages

With the increase of forest gap ages, the content of C in 0–10 cm and 10–20 cm soil layers increased gradually (Figure 2). In the 0–10 cm soil layer, the C content in the 10–20 years forest gap soil increased by 28.6% compared with pure forest. In the 0–10 cm soil layer and the 10–20 cm soil layer, the N content in 10–20 years forest gap soil increased by 52.5% and 21.8% compared with pure forest, respectively. In the 0–10 cm soil layer and the 10–20 cm soil layer, the P content in the soil of >20 years forest gap increased by 54.9% and 43.2% compared with pure forest, respectively. The results showed that the contents of C, N, and P in soil increased with the increase of forest gap ages and were significantly higher than those in Cryptomeria japonica pure forest (p < 0.05). The nutrient contents in 10–20 years were the highest, and the nutrient contents in 0–10 cm soil layer were higher than those in 0–20 cm soil layer.

3.5. Soil Stoichiometric Characteristics in Forest Gap of Different Ages

In the 0–10 cm soil layer, the C:N in the soil of 10–20 years forest gap was 15.7% and 18.7% lower than pure forest and <10 years, respectively (Figure 3). The C:P in soil showed a decreasing trend with the increase of forest gap ages. In the 0–10 cm soil layer, the forest gap of >20 years was 31.6% and 44.5% lower than pure forest and <10 years, respectively. The N:P in the soil showed a decreasing trend with the increase of forest gap ages. In the soil layers of 0–10 cm and 10–20 cm, the N:P in the soil of >20 years forest gap decreased by 27.6% and 43.8% compared with pure forest, respectively. The C:N ratio of soil is an indicator to measure the mineralization rate of organic matter. The lower C:N ratio can indicate faster nutrient cycling, whilst C:N stoichiometric ratio is best used to measure the rate of nutrient cycling. The results showed that with the increase of Cryptomeria japonica forest gap ages, the C:P and N:P in the soil showed an overall decreasing trend, while the C:N of 10–20 years forest gap soil was significantly smaller than other forest gap ages (p < 0.05) which indicated that nutrient cycling in 10–20 years forest gap was the fastest.

4. Discussion

4.1. Effects of Different Forest Gap Ages on Soil Water Holding Capacity, Bulk Density, and Porosity

In this experiment, by studying the age of natural forest gap formation and succession of Cryptomeria japonica in Lushan Mountain, the dynamic process of soil water holding capacity, bulk density, and porosity with different forest gap ages was discussed. Soil water holding capacity, one of the most important physical properties of soil, is an important factor determining the water conservation capacity of an ecosystem [33]. Soil water holding capacity is an important index to evaluate soil water conservation function, which has an extremely important impact on the restoration and reconstruction of ecological communities [34]. The maximum water holding capacity, capillary water holding capacity, and field water holding capacity of soil can directly reflect the water holding capacity of soil, and indirectly reflect the redistribution ability of water [35]. The soil maximum water holding capacity, field water holding capacity, and capillary water holding capacity increased significantly with the increase of forest gap ages after 10 years (Table 1). In the 0–10 cm soil layer, the maximum water holding capacity, field water holding capacity, and capillary water holding capacity of the soil in the gap of >20 years were significantly higher than those in the gap of <10 years and the gap of 10–20 years (p < 0.05). The results showed that the restoration of Cryptomeria japonica forest gap could improve the physical properties of surface soil moisture and enhance soil water retention capacity. This may be because the pure Cryptomeria japonica forest generally has high density, small coverage of undergrowth vegetation, few species, and low biodiversity. In the early stage after the formation of forest gap, the undergrowth vegetation is in the growth and development stage because of the change of surface cover, and the soil water holding capacity and water holding capacity will decrease. However, with the increase of restoration years, the composition and structure of vegetation are optimized, and the soil water holding capacity is gradually restored and enhanced.
Soil bulk density and porosity are important physical properties of soil, reflecting the compactness of soil structure, and can affect soil water permeability and root extension [36]. There are many large and small pores in the soil, which can reflect the size of the total pore volume in the soil and the distribution and matching of the pores, that is, the structure of the soil [37]. Soil pores are occupied by water and gas, and the size of total soil porosity is mainly determined by the arrangement of soil particles [38]. The pores that can be occupied by capillary water are capillary pores, while those that cannot be occupied by capillary water are non-capillary pores [39]. Through the study of total soil porosity, capillary porosity, and non-capillary porosity, we can understand the structural state of soil and further determine the existence state of water in soil [40]. With the increase of forest gap ages, soil capillary porosity and total porosity increased significantly compared with pure forest (p < 0.05) (Table 2). In the 0–10 cm soil layer, the soil bulk density of >20 years forest gap was significantly lower than that of forest gap restored to 10–20 years (p < 0.05). In the 10–20 cm soil layer, the soil bulk density of >20 years forest gap was significantly lower than that of pure forest (p < 0.05).
This study showed that with the increase of forest gap age, the capillary porosity and total porosity of soil increased significantly, and the soil bulk density of 10–20 cm soil layer showed a decreasing trend, indicating that the soil of >20 years forest gap showed a looser structure, which improved the soil structure compared with Cryptomeria japonica pure forest. This may be due to the formation of forest gaps which can increase the light intensity in the forest to a certain extent, which is conducive to the development of undergrowth vegetation, and in addition the root system increases accordingly. The roots of undergrowth grass and shrub are mainly concentrated in the 0–10 cm soil layer, and the roots are interspersed and squeezed in the soil. With the increase of forest gap age, the bulk density of soil surface layer decreases and the porosity of soil increases.

4.2. Effects of Different Forest Gap Ages on Particle Size Distribution of Soil Aggregates

Aggregate is the basic unit of various types of soil structure, which is an important material basis for people to study and improve various types of soil structure. It can comprehensively reflect the soil structure integrity and soil fertility status of various types of soil [41]. The formation of soil aggregates is a complex physical, chemical, biological, and biochemical process. Soil aggregate status is the central regulator of soil fertility, which greatly affects soil aeration and erosion resistance [42]. The degradation of soil first shows the disappearance of soil aggregate structure, and different particle size aggregates play a crucial role in the storage, transport, and transformation of nutrient substances [43]. In this study, the aggregates of >2 mm and 1–2 mm were dominant in the 0–10 cm and 10–20 cm soil layers of Cryptomeria japonica pure forest and forest gap of different ages (Table 3), and the aggregates of 1–2 mm, 0.5–1 mm, and 0.25–0.5 mm showed an overall increasing trend with the increase of forest gap recovery years in 0–10 cm and 10–20 cm soil layers (p < 0.05). The formation of forest gap changed the distribution of soil aggregates, and the proportion of large particle aggregates increased with the increase of gap ages. Large particle aggregates are formed by cementation of organic matter and microaggregates, and the organic carbon content is high [44]. Large particle aggregates are the basis of soil structure stability and the main part of organic carbon storage. The increase of large particle aggregates content has a good effect on improving soil structure [45].

4.3. Effects of Different Forest Gap Ages on Soil Nutrient Characteristics

Soil is an important component of terrestrial ecosystems and the main source of nutrients for plant growth and development [46]. Carbon (C), nitrogen (N), and phosphorus (P) in soil are essential nutrients for plant growth. As a stable and long-lasting carbon source, soil organic carbon plays an important role in maintaining soil fertility. Its quality (the activity level of organic carbon) and the content affects the potential productivity of the soil [47,48]. After the Cryptomeria japonica forest gap was formed, the C content in the soil showed a gradually increasing trend with the increase of the restoration period, and the C content in the 0–10 cm soil layer was generally higher than that in the 10–20 cm soil layer (Figure 2). In the 10–20 cm soil layer, the N content in the soil of 10–20 years forest gap was significantly higher than pure forest and <10 years forest gap (p < 0.05). And in the 0–10 cm soil layer, the soil P content of >20 years forest gap was significantly higher than <10 years forest gap and pure forest (p < 0.05). The results showed that with the increase of forest gap ages, the contents of C, N, and P in soil showed an overall increasing trend and were significantly higher than those in pure forest (p < 0.05). The nutrient content of forest gap with 10–20 years was the highest, and the nutrient content of the 0–10 cm soil layer is generally greater than that of the 0–20 cm soil layer. This may be because Cryptomeria japonica forest gap changed the light conditions and rainfall conditions in the forest, and the temperature and humidity in the forest gap changed accordingly, which affected the activity of soil microorganisms, thus causing changes in soil nutrient element content. With the increase of forest gap ages, the plant species in the forest gap became more abundant, and the decomposition of litter increased the C, N, and P contents in the soil.

4.4. Effects of Different Forest Gap Ages on Soil Stoichiometric Characteristics

Ecological stoichiometry is a theoretical science that uses the coupling relationship of various chemical elements in the ecological process to analyze the interaction of various chemical elements on the ecosystem. It integrates the basic principles of biology, physics, and chemistry [49]. Due to the regulation of natural conditions such as soil parent material, climate, landform, and vegetation cover, as well as the interference of human activities and differences in soil hydrothermal conditions and pedogenesis, soil stoichiometric characteristics have great spatial variability [50]. Carbon © is the most important element that constitutes dry matter in plants. Nitrogen (N) and phosphorus (P) are essential and limiting elements for plant growth and are closely related to plant growth, development, and reproduction. Changes in nutrient distribution patterns (such as C:N, N:P, C:P) affect community structure, nutrient use efficiency, and productivity [51]. Gap is an important driving force for natural regeneration of forests, an important channel for regulating the reorganization of plantation vegetation and plays an important role in vegetation succession and nutrient cycling in forest ecosystems [52]. On the one hand, the formation of gaps can affect the microenvironment below the canopy, the invasion and settlement of plants, and the regeneration of understory vegetation, thereby changing the stand structure, which may exert a strong effect on the soil stoichiometric characteristics of gaps [53]. On the other hand, compared with the canopy forest, the formation of gaps changes the water and heat dynamics and the community structure of decomposers in the forest, which can affect the nutrient utilization and turnover efficiency (such as litter decomposition) of the understory vegetation, and then profoundly affects the soil nutrients’ distribution pattern [54]. Soil C:N is a sensitive indicator reflecting soil quality and an important factor affecting the carbon and nitrogen cycle in soil. The evolution trend of C:N has an important impact on soil C and N cycles [55]. Soil C:N can indicate the C decomposition rate, and a lower C:N ratio indicates a faster C decomposition rate [56].
In this experiment, the soil C:N in 10–20 years Cryptomeria japonica forest gap was significantly smaller than other forest gap ages and pure forest (p < 0.05), indicating that in the 10–20 years Cryptomeria japonica forest gap, the soil C decomposition rate was faster than other ages, and the nutrient cycling period was the shortest. The C:P in soil can be used as an indicator to measure the availability of soil P, which is an important indicator to measure the potential of soil organic matter mineralization to release phosphorus or absorb and retain phosphorus. A lower C:P indicates a higher availability of soil P in the study area [57]. In this experiment, with the increase of Cryptomeria japonica forest gap ages, the C:P in the soil showed an overall decreasing trend, indicating that the effectiveness of soil P in the gaps gradually increased. This may be due to the better nutrient release by microorganisms in the process of organic matter decomposition, which promotes the increase of soil available phosphorus. N and P elements in soil are common and important elements required for plant growth, and N:P in soil can be used as an indicator of plant nutrient limitation and is often used for the diagnosis of soil nutrient limiting factors and the determination of nutrient limitation thresholds [58]. In this experiment, soil N:P showed a decreasing trend with the increase of Cryptomeria japonica forest gap ages, especially >20 years forest gap which were significantly smaller than other forest gap ages and pure forests (p < 0.05). Combined with the gradual increase in soil P content, this may be due to the fact that soil N content is the main nutrient limiting factor [59].

5. Conclusions

In this study, the effects of different Cryptomeria japonica forest gap ages (<10 years, 10–20 years, >20 years) on soil physical properties and stoichiometric characteristics were analyzed. With the increase of forest gap ages, the water physical properties of soil surface were improved and the soil water holding capacity was enhanced. The capillary porosity and total porosity of soil increased significantly, and the soil bulk density of 10–20 cm soil layer showed a decreasing trend, indicating that the soil of >20 years forest gap showed a looser structure, which improved the soil structure compared with Cryptomeria japonica pure forest. The increase of forest gap restoration years is conducive to the increase of the content of large particle soil aggregates. The large particle aggregates are formed by the cementation of organic matter and microaggregates, and the organic carbon content is higher. Large particle aggregates are the basis of soil structure stability and the main part of organic carbon storage. The increase of large particle aggregates content has a good effect on improving soil structure. The contents of C, N, and P in soil showed an overall increasing trend with the increase of gap age and were significantly higher than those in pure forest (p < 0.05). The nutrient content of forest gap in 10–20 years was the highest, and the nutrient content of 0–10 cm soil layer was generally higher than that of 0–20 cm soil layer. The C:P and N:P in soil showed an overall decreasing trend, while the C:N in 10–20 years gaps was significantly lower than other forest gap ages (p < 0.05). The results showed that with the increase of forest gap ages, the soil physical properties and stoichiometric characteristics in the forest gap were improved, which was more conducive to the growth of vegetation in the forest gap.

Author Contributions

Conceptualization, T.X., C.W. and Y.L.; Methodology, T.X., C.W., X.Y., L.T., P.L. and W.D.; Data curation and analysis, T.X. and C.W.; writing—original draft, T.X.; writing—review and editing, T.X. and Y.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was financially supported by Lushan Mountain Cryptomeria japonica and Chamaecyparis obtusa forest phase transformation and renewal technology pilot demonstration project (No. 9022109068).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

We would like to thank Xing-Yue Mo and Ling-Bo Qiu for their help with field sampling and laboratory measurement.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Kneeshaw, D.D.; Bergeron, Y. Canopy gap characteristics and tree replacement in the southeastern boreal forest. Ecology 1998, 79, 783–794. [Google Scholar] [CrossRef]
  2. Muscolo, A.; Bagnato, S.; Sidari, M.; Mercurio, R. A review of the roles of forest canopy gaps. J. For. Res. 2014, 25, 725–736. [Google Scholar] [CrossRef]
  3. Keram, A.; Halik, Ü.; Keyimu, M.; Aishan, T.; Mamat, Z.; Rouzi, A. Gap dynamics of natural Populus euphratica floodplain forests affected by hydrological alteration along the Tarim River: Implications for restoration of the riparian forests. For. Ecol. Manag. 2019, 438, 103–113. [Google Scholar] [CrossRef]
  4. Madsen, P.; Hahn, K. Natural regeneration in a beech-dominated forest managed by close-to-nature principles—A gap cutting based experiment. Can. J. For. Res. 2008, 38, 1716–1729. [Google Scholar] [CrossRef]
  5. Li, H.; Du, T.; Chen, Y.L.; Zhang, Y.; Yang, Y.L.; Yang, J.P.; Dong, Q.; Zhang, L.; Wu, Q.G. Effects of forest gaps on Abies faxoniana Rehd. leaf litter mass loss and carbon release along an elevation gradient in a subalpine forest. Forests 2022, 13, 1201. [Google Scholar] [CrossRef]
  6. He, W.; Wu, F.Z.; Zhang, D.J.; Yang, W.Q.; Tan, B.; Zhao, Y.Y.; Wu, Q.Q. The effects of forest gaps on cellulose degradation in the foliar litter of two shrub species in an alpine fir forest. Plant Soil 2015, 393, 109–122. [Google Scholar] [CrossRef]
  7. Gong, S.H.; Xiao, Y.; Xiao, Y.; Zhang, L.; Ouyang, Z.Y. Driving forces and their effects on water conservation services in forest ecosystems in China. Chin. Geogr. Sci. 2017, 27, 216–228. [Google Scholar] [CrossRef] [Green Version]
  8. Pu, H.M.; Song, W.F.; Wu, J.K. Using soil water stable isotopes to investigate soil water movement in a water conservation forest in Hani Terrace. Water 2020, 12, 3520. [Google Scholar] [CrossRef]
  9. Huang, L.M.; Shao, M.A. Advances and perspectives on soil water research in China’s Loess Plateau. Earth-Sci. Rev. 2019, 199, 102962. [Google Scholar] [CrossRef]
  10. Mao, J.F.; Zhang, K.; Chen, B.L. Linking hydrophobicity of biochar to the water repellency and water holding capacity of biochar-amended soil. Environ. Pollut. 2019, 253, 779–789. [Google Scholar] [CrossRef]
  11. Lal, R. Soil organic matter and water retention. Agron. J. 2020, 112, 3265–3277. [Google Scholar] [CrossRef]
  12. Franko, U.; Schulz, E. Carbon accumulation in a bare fallow Chernozem soil with high carbon input rates. Eur. J. Soil Sci. 2021, 72, 265–273. [Google Scholar] [CrossRef] [Green Version]
  13. Yang, F.; Zhang, G.L.; Yang, J.L.; Li, D.C.; Zhao, Y.G.; Liu, F.; Yang, R.M.; Yang, F. Organic matter controls of soil water retention in an alpine grassland and its significance for hydrological processes. J. Hydrol. 2014, 519, 3086–3093. [Google Scholar] [CrossRef]
  14. Manns, H.R.; Parkin, G.W.; Martin, R.C. Evidence of a union between organic carbon and water content in soil. Can. J. Soil Sci. 2016, 96, 305–316. [Google Scholar] [CrossRef] [Green Version]
  15. Tang, X.L.; Fan, S.H.; Du, M.Y.; Zhang, W.J.; Gao, S.C.; Liu, S.B.; Chen, G.; Yu, Z.; Yang, W.N. Spatial and temporal patterns of global soil heterotrophic respiration in terrestrial ecosystems. Earth Syst. Sci. Data 2020, 12, 1037–1051. [Google Scholar] [CrossRef]
  16. Wang, Y.P.; Law, R.M.; Pak, B. A global model of carbon, nitrogen and phosphorus cycles for the terrestrial biosphere. Biogeosciences 2010, 7, 2261–2282. [Google Scholar] [CrossRef] [Green Version]
  17. Zhang, Y.; Li, P.; Liu, X.J.; Xiao, L.; Shi, P.; Zhao, B.H. Effects of farmland conversion on the stoichiometry of carbon, nitrogen, and phosphorus in soil aggregates on the Loess Plateau of China. Geoderma 2019, 351, 188–196. [Google Scholar] [CrossRef]
  18. Yu, M.F.; Tao, Y.X.; Liu, W.Z.; Xing, W.; Liu, G.H.; Wang, L.; Ma, L. C, N, and P stoichiometry and their interaction with different plant communities and soils in subtropical riparian wetlands. Environ. Sci. Pollut. Res. 2020, 27, 1024–1034. [Google Scholar] [CrossRef]
  19. Fan, H.B.; Wu, J.P.; Liu, W.F.; Yuan, Y.H.; Hu, L.; Cai, Q.K. Linkages of plant and soil C:N:P stoichiometry and their relationships to forest growth in subtropical plantations. Plant Soil 2015, 392, 127–138. [Google Scholar] [CrossRef]
  20. Wang, Y.; Ren, Z.; Ma, P.P.; Wang, Z.M.; Niu, D.C.; Fu, H.; Elser, J.J. Effects of grassland degradation on ecological stoichiometry of soil ecosystems on the Qinghai-Tibet Plateau. Sci. Total Environ. 2020, 722, 137910. [Google Scholar] [CrossRef]
  21. Boltenstern, S.Z.; Keiblinger, K.M.; Mooshammer, M.; Peñuelas, J.; Richter, A.; Sardans, J.; Wanek, W. The application of ecological stoichiometry to plant–microbial–soil organic matter transformations. Ecol. Monogr. 2015, 85, 133–155. [Google Scholar] [CrossRef] [Green Version]
  22. Sistla, S.A.; Schimel, J.P. Stoichiometric flexibility as a regulator of carbon and nutrient cycling in terrestrial ecosystems under change. New Phytol. 2012, 196, 68–78. [Google Scholar] [CrossRef] [PubMed]
  23. Wu, Y.; Chen, W.J.; Li, Q.; Guo, Z.Q.; Li, Y.Z.; Zhao, Z.W.; Zhai, J.Y.; Liu, G.B.; Xue, S. Ecoenzymatic stoichiometry and nutrient limitation under a natural secondary succession of vegetation on the Loess Plateau, China. Land Degrad. Dev. 2021, 32, 399–409. [Google Scholar] [CrossRef]
  24. Waring, B.G.; Weintraub, S.R.; Sinsabaugh, R.L. Ecoenzymatic stoichiometry of microbial nutrient acquisition in tropical soils. Biogeochemistry 2014, 117, 101–113. [Google Scholar] [CrossRef]
  25. Wang, M.M.; Chen, H.S.; Zhang, W.; Wang, K.L. Soil nutrients and stoichiometric ratios as affected by land use and lithology at county scale in a karst area, southwest China. Sci. Total Environ. 2018, 619, 1299–1307. [Google Scholar] [CrossRef]
  26. Wang, L.J.; Wang, P.; Sheng, M.Y.; Tian, J. Ecological stoichiometry and environmental influencing factors of soil nutrients in the karst rocky desertification ecosystem, southwest China. Glob. Ecol. Conserv. 2018, 16, 100449. [Google Scholar] [CrossRef]
  27. Kitagami, Y.; Tanikawa, T.; Matsuda, Y. Effects of microhabitats and soil conditions on structuring patterns of nematode communities in Cryptomeria japonica (Cryptomeria japonica) plantation forests under temperate climate conditions. Soil Biol. Biochem. 2020, 151, 108044. [Google Scholar] [CrossRef]
  28. Liu, W.; Liao, L.Q.; Liu, Y.Q.; Wang, Q.; Murray, P.J.; Jiang, X.R.; Zou, G.W.; Cai, J.H.; Zhao, X.M. Effects of Phyllostachys pubescens expansion on underground soil fauna community and soil food web in a Cryptomeria japonica plantation, Lushan Mountain, subtropical China. J. Soils Sediments 2021, 21, 2212–2227. [Google Scholar] [CrossRef]
  29. Bai, T.J.; Liu, Y.Q.; Wen, L.S.; Pan, J.; Cao, W.; Zheng, X.L.; Zou, Q.; Deng, W.P. Response of earlywood and latewood ring width of Cryptomeria japonica to climate change in Lushan Mountain, eastern China. J. Beijing For. Univ. 2020, 42, 61–69. (In Chinese) [Google Scholar]
  30. Zheng, Y.H.; Zhang, Y.Y.; Wang, D.; Yu, J.H.; Wang, J.L. Marginal effect of radial growth of Cryptomeria japonica to climate in Lushan Mountain of southwestern China. J. Beijing For. Univ. 2021, 43, 63–69. (In Chinese) [Google Scholar]
  31. Velázquez, E.; Wiegand, T. Competition for light and persistence of rare light-demanding species within tree-fall gaps in a moist tropical forest. Ecology 2020, 101, 103034. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  32. Morin, X.; Damestoy, T.; Toigo, M.; Castagneyrol, B.; Jactel, H.; Coligny, F.D.; Meredieu, C. Using forest gap models and experimental data to explore long-term effects of tree diversity on the productivity of mixed planted forests. Ann. For. Sci. 2020, 77, 50. [Google Scholar] [CrossRef]
  33. Zhang, Y.W.; Wang, K.B.; Wang, J.; Liu, C.H.; Shangguan, Z.P. Changes in soil water holding capacity and water availability following vegetation restoration on the Chinese Loess Plateau. Sci. Rep.-UK 2021, 11, 9692. [Google Scholar] [CrossRef]
  34. Wang, Y.C.; Zhao, J.; Fu, J.W.; Wei, W. Effects of the Grain for Green Program on the water ecosystem services in an arid area of China—Using the Shiyang River Basin as an example. Ecol. Indic. 2019, 104, 659–668. [Google Scholar] [CrossRef]
  35. Liu, C.; Wang, H.L.; Tang, X.Y.; Guan, Z.; Reid, B.J.; Rajapaksha, A.U.; Ok, Y.S.; Sun, H. Biochar increased water holding capacity but accelerated organic carbon leaching from a sloping farmland soil in China. Environ. Sci. Pollut. Res. 2016, 23, 995–1006. [Google Scholar] [CrossRef]
  36. Tracy, S.R.; Black, C.R.; Roberts, J.A.; Mooney, S.J. Soil compaction: A review of past and present techniques for investigating effects on root growth. J. Sci. Food Agric. 2011, 91, 1528–1537. [Google Scholar] [CrossRef] [PubMed]
  37. Rasa, K.; Heikkinen, J.; Hannula, M.; Arstila, K.; Kulju, S.; Hyväluoma, J. How and why does willow biochar increase a clay soil water retention capacity? Biomass Bioenergy 2018, 119, 346–353. [Google Scholar] [CrossRef]
  38. Pagliai, M.; Vignozzi, N.; Pellegrini, S. Soil structure and the effect of management practices. Soil Tillage Res. 2004, 79, 131–143. [Google Scholar] [CrossRef]
  39. Kutílek, M. Soil hydraulic properties as related to soil structure. Soil Tillage Res. 2004, 79, 175–184. [Google Scholar] [CrossRef]
  40. Wu, G.L.; Yang, Z.; Cui, Z.; Liu, Y.; Fang, N.F.; Shi, Z.H. Mixed artificial grasslands with more roots improved mine soil infiltration capacity. J. Hydrol. 2016, 535, 54–60. [Google Scholar] [CrossRef]
  41. Rillig, M.C.; Mummey, D.L. Mycorrhizas and soil structure. New Phytol. 2006, 171, 41–53. [Google Scholar] [CrossRef] [PubMed]
  42. Gupta, V.V.S.R.; Germida, J.J. Soil aggregation: Influence on microbial biomass and implications for biological processes. Soil Biol. Biochem. 2015, 80, 3–9. [Google Scholar] [CrossRef]
  43. Six, J.; Bossuyt, H.; Degryze, S.; Denef, K. A history of research on the link between (micro)aggregates, soil biota, and soil organic matter dynamics. Soil Tillage Res. 2004, 79, 7–31. [Google Scholar] [CrossRef]
  44. Cao, S.; Zhou, Y.Z.; Zhou, Y.Y.; Zhou, X.; Zhou, W.J. Soil organic carbon and soil aggregate stability associated with aggregate fractions in a chronosequence of citrus orchards plantations. J. Environ. Manag. 2021, 293, 112847. [Google Scholar] [CrossRef] [PubMed]
  45. Cen, R.; Feng, W.Y.; Yang, F.; Wu, W.Y.; Liao, H.Q.; Qu, Z.Y. Effect mechanism of biochar application on soil structure and organic matter in semi-arid areas. J. Environ. Manag. 2021, 286, 112198. [Google Scholar] [CrossRef]
  46. Pugnaire, F.I.; Morillo, J.A.; Peñuelas, J.; Reich, P.B.; Bardgett, R.D.; Gaxiola, A.; Wardle, D.A.; Putten, W.V.D. Climate change effects on plant-soil feedbacks and consequences for biodiversity and functioning of terrestrial ecosystems. Sci. Adv. 2019, 5, 1834. [Google Scholar] [CrossRef] [Green Version]
  47. Xiong, J.L.; Dong, L.W.; Lu, J.L.; Hu, W.G.; Gong, H.Y.; Xie, S.B.; Zhao, D.M.; Zhang, Y.H.; Wang, X.T.; Deng, Y.; et al. Variation in plant carbon, nitrogen and phosphorus contents across the drylands of China. Funct. Ecol. 2022, 36, 174–186. [Google Scholar] [CrossRef]
  48. Liu, K.L.; Li, Y.Z. Different response of grain yield to soil organic carbon, nitrogen, and phosphorus in red soil as based on the long-term fertilization experiment. Eurasian Soil Sci. 2018, 51, 1507–1513. [Google Scholar]
  49. Hessen, D.O.; Elser, J.J.; Sterner, R.W.; Urabe, J. Ecological stoichiometry: An elementary approach using basic principles. Limnol. Oceanogr. 2013, 58, 2219–2236. [Google Scholar] [CrossRef]
  50. Liu, F.T.; Wang, X.Q.; Chi, Q.H.; Tian, M. Spatial variations in soil organic carbon, nitrogen, phosphorus contents and controlling factors across the “Three Rivers” regions of southwest China. Sci. Total Environ. 2021, 794, 148795. [Google Scholar] [CrossRef]
  51. Marzi, M.; Shahbazi, K.; Kharazi, N.; Rezaei, M. The influence of organic amendment source on carbon and nitrogen mineralization in different soils. J. Soil Sci. Plant. Nut. 2020, 20, 177–191. [Google Scholar] [CrossRef]
  52. Bugmann, H. A review of forest gap models. Clim. Chang. 2001, 51, 259–305. [Google Scholar] [CrossRef]
  53. Tan, B.; Zhang, J.; Yang, W.Q.; Yin, R.; Xu, Z.F.; Liu, Y.; Zhang, L.; Li, H.; You, C.M. Forest gaps retard carbon and nutrient release from twig litter in alpine forest ecosystems. Eur. J. For. Res. 2020, 139, 53–65. [Google Scholar] [CrossRef]
  54. Gálhidy, L.; Mihók, B.; Hagyó, A.; Rajkai, K.; Standovár, T. Effects of gap size and associated changes in light and soil moisture on the understorey vegetation of a Hungarian beech forest. Plant Ecol. 2006, 183, 133–145. [Google Scholar] [CrossRef]
  55. Ren, C.J.; Zhao, F.Z.; Kang, D.; Yang, G.H.; Han, X.H.; Tong, X.G.; Feng, Y.Z.; Ren, G.X. Linkages of C:N:P stoichiometry and bacterial community in soil following afforestation of former farmland. For. Ecol. Manag. 2016, 376, 59–66. [Google Scholar] [CrossRef]
  56. Ostrowska, A.; Porębska, G. Assessment of the C/N ratio as an indicator of the decomposability of organic matter in forest soils. Ecol. Indic. 2015, 49, 104–109. [Google Scholar] [CrossRef]
  57. Fujita, K.; Miyabara, Y.; Kunito, T. Microbial biomass and ecoenzymatic stoichiometries vary in response to nutrient availability in an arable soil. Eur. J. Soil Biol. 2019, 91, 1–8. [Google Scholar] [CrossRef]
  58. Liu, Z.F.; Fu, B.J.; Zheng, X.X.; Liu, G.H. Plant biomass, soil water content and soil N:P ratio regulating soil microbial functional diversity in a temperate steppe: A regional scale study. Soil Biol. Biochem. 2009, 42, 445–450. [Google Scholar] [CrossRef]
  59. Du, E.Z.; Terrer, C.; Pellegrini, A.F.A.; Ahlström, A.; Lissa, C.J.V.; Zhao, X.; Xia, N.; Wu, X.H.; Jackson, R.B. Global patterns of terrestrial nitrogen and phosphorus limitation. Nat. Geosci. 2020, 13, 221–226. [Google Scholar] [CrossRef]
Forests 13 01708 g001 550
Figure 1. Location of the study site.
Figure 1. Location of the study site.
Forests 13 01708 g001
Forests 13 01708 g002 550
Figure 2. Variations of C content (a), N content (b), and P content (c) in different forest gap ages. Note: Different letters indicate significant differences between different forest gap ages in the same soil layer (p < 0.05). Error bars represent ±standard errors.
Figure 2. Variations of C content (a), N content (b), and P content (c) in different forest gap ages. Note: Different letters indicate significant differences between different forest gap ages in the same soil layer (p < 0.05). Error bars represent ±standard errors.
Forests 13 01708 g002
Forests 13 01708 g003 550
Figure 3. Variations of C:N ratio (a), C:P ratio (b), and N:P ratio (c) in different forest gap ages. Note: Different letters indicate significant differences between different forest gap ages in the same soil layer (p < 0.05). Error bars represent ±standard errors.
Figure 3. Variations of C:N ratio (a), C:P ratio (b), and N:P ratio (c) in different forest gap ages. Note: Different letters indicate significant differences between different forest gap ages in the same soil layer (p < 0.05). Error bars represent ±standard errors.
Forests 13 01708 g003
Table
Table 1. Soil water holding capacity characteristics in forest gap of different ages.
Table 1. Soil water holding capacity characteristics in forest gap of different ages.
Different Forest
Gap Ages		Soil Depth/cmMaximum Water Holding Capacity/g·kg−1Field Water
Holding Capacity/g·kg−1		Capillary Water
Holding Capacity/g·kg−1
Pure forest (CK)0–10882.88 ± 44.91 ab709.84 ± 36.44 a778.77 ± 39.11 a
10–20793.24 ± 54.29 a623.14 ± 42.02 a684.85 ± 48.26 a
<10 years0–10706.55 ± 69.17 c529.95 ± 64.47 b604.93 ± 62.01 c
10–20687.90 ± 51.97 b494.70 ± 48.02 b566.95 ± 48.29 b
10–20 years0–10818.27 ± 25.10 b578.15 ± 20.17 b696.88 ± 22.14 b
10–20817.64 ± 34.95 a587.87 ± 28.45 a692.87 ± 34.14 a
>20 years0–10960.96 ± 60.15 a658.58 ± 39.22 a775.67 ± 40.26 a
10–20837.31 ± 37.58 a592.19 ± 42.89 a712.31 ± 38.29 a
Note: The values in the table are mean ± standard error. Different letters indicate significant differences between different forest gap ages in the same soil layer (p < 0.05).
Table
Table 2. Soil bulk density and porosity characteristics in forest gap of different ages.
Table 2. Soil bulk density and porosity characteristics in forest gap of different ages.
Different Forest
Gap Ages		Soil Depth/cmBulk Density/g·cm−3Capillary
Porosity/%		Non-Capillary Porosity/%Total
Porosity/%
Pure forest (CK)0–100.75 ± 0.03 c55.18 ± 1.01 b7.23 ± 0.61 c62.41 ± 0.97 b
10–200.85 ± 0.04 a53.80 ± 1.88 b8.58 ± 1.49 b62.37 ± 1.77 c
<10 years0–100.72 ± 0.04 c58.70 ± 2.01 a9.15 ± 1.06 b67.85 ± 2.54 a
10–200.79 ± 0.05 b60.92 ± 1.82 a9.80 ± 1.15 a70.73 ± 2.13 a
10–20 years0–100.84 ± 0.03 a58.64 ± 2.33 a8.54 ± 0.83 b67.18 ± 2.45 a
10–200.86 ± 0.04 a59.53 ± 2.83 a7.41 ± 0.79 c66.94 ± 3.10 b
>20 years0–100.76 ± 0.04 b59.50 ± 1.92 a10.21 ± 0.83 a69.71 ± 2.15 a
10–200.78 ± 0.03 b56.98 ± 2.19 b8.87 ± 0.99 b65.85 ± 2.45 b
Note: The values in the table are mean ± standard error. Different letters indicate significant differences between different forest gap ages in the same soil layer (p < 0.05).
Table
Table 3. Soil aggregate particle size distribution in forest gap of different ages.
Table 3. Soil aggregate particle size distribution in forest gap of different ages.
Different Forest
Gap Ages		Soil Depth/cmSoil Aggregate Particle Size Distribution/%
>2 mm1–2 mm0.5–1 mm0.25–0.5 mm0.106–0.25 mm<0.106 mm
Pure forest (CK)0–1048.03 ± 1.95 a18.04 ± 0.68 b14.72 ± 0.86 b9.02 ± 0.44 b5.79 ± 0.62 a4.40 ± 0.25 b
10–2045.87 ± 1.84 a18.48 ± 0.97 c13.92 ± 0.72 b9.37 ± 0.47 b6.81 ± 0.79 a5.55 ± 0.41 a
<10 years0–1043.57 ± 2.81 b21.23 ± 1.48 a15.15 ± 1.04 ab10.08 ± 0.77 a5.32 ± 0.43 a4.65 ± 0.35 b
10–2042.32 ± 2.04 a21.94 ± 0.71 b14.28 ± 0.74 b11.45 ± 0.52 a5.49 ± 0.52 b4.52 ± 0.33 b
10–20 years0–1040.94 ± 4.28 c22.15 ± 2.67 a15.86 ± 1.31 ab9.18 ± 0.80 a5.81 ± 0.98 a6.06 ± 0.69 a
10–2044.49 ± 4.18 a22.04 ± 1.81 ab14.11 ± 1.38 b8.56 ± 1.07 b4.75 ± 0.30 c6.05 ± 1.20 a
>20 years0–1040.23 ± 2.40 c23.08 ± 1.08 a17.08 ± 1.04 a10.14 ± 1.34 a5.28 ± 0.52 a4.19 ± 0.44 b
10–2034.34 ± 3.22 b24.82 ± 1.10 a17.53 ± 1.61 a12.03 ± 1.51 a6.92 ± 0.47 a4.36 ± 0.43 b
Note: The values in the table are mean ± standard error. Different letters indicate significant differences between different forest gap ages in the same soil layer (p < 0.05).
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Xiao, T.; Wang, C.; Yuan, X.; Tao, L.; Li, P.; Deng, W.; Liu, Y. Effects of Different Forest Gap Ages on Soil Physical Properties and Stoichiometric Characteristics in Cryptomeria japonica plantations (L.f.) D.Don, 1839. Forests 2022, 13, 1708. https://0-doi-org.brum.beds.ac.uk/10.3390/f13101708

AMA Style

Xiao T, Wang C, Yuan X, Tao L, Li P, Deng W, Liu Y. Effects of Different Forest Gap Ages on Soil Physical Properties and Stoichiometric Characteristics in Cryptomeria japonica plantations (L.f.) D.Don, 1839. Forests. 2022; 13(10):1708. https://0-doi-org.brum.beds.ac.uk/10.3390/f13101708

Chicago/Turabian Style

Xiao, Tingqi, Chen Wang, Xi Yuan, Lingjian Tao, Peng Li, Wenping Deng, and Yuanqiu Liu. 2022. "Effects of Different Forest Gap Ages on Soil Physical Properties and Stoichiometric Characteristics in Cryptomeria japonica plantations (L.f.) D.Don, 1839" Forests 13, no. 10: 1708. https://0-doi-org.brum.beds.ac.uk/10.3390/f13101708

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop