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Assessing the Resource Potential of Mountainous Forests: A Comparison between Austria and Japan
评估山地森林的资源潜力——奥地利与日本的比较

Mathias Leiter 1,*
马蒂亚斯·莱特 1，*

Citation: Leiter, M.; Neumann, M.; Egusa, T.; Harashina, K.; Hasenauer, H. Assessing the Resource Potential of Mountainous Forests: A
引自： Leiter， M.;诺依曼，M.;埃古萨，T.;原名，K.;Hasenauer， H. 评估山地森林的资源潜力：A

Comparison between Austria and Japan. Forests 2022, 13, 891.
奥地利和日本的比较。森林202213,891。

https://doi.org/10.3390/f13060891 Academic Editor: Michael Sprintsin
https://doi.org/10.3390/f13060891Academic 编辑：Michael Sprintsin

Received: 5 May 2022 Accepted: 6 June 2022 Published: 7 June 2022
收稿日期： 2022-05-05-05 录用日期： 2022-06-06 出版日期： 2022-06-07

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Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
版权所有：© 2022 作者。被许可人MDPI，瑞士巴塞尔。本文是一篇开放获取文章，根据知识共享署名 （CC BY） 许可 （https://creativecommons.org/licenses/by/4.0/） 的条款和条件分发。

1 Department of Forest- and Soil Sciences, Institute of Silviculture, University of Natural Resources and Life Sciences, 1190 Vienna, Austria; mathias.neumann@boku.ac.at (M.N.); hubert.hasenauer@boku.ac.at (H.H.)
1 自然资源和生命科学大学造林研究所森林和土壤科学系，奥地利维也纳，1190年;mathias.neumann@boku.ac.at（M.N.）;hubert.hasenauer@boku.ac.at （H.H.）

2 Faculty of Agriculture, Shizuoka University, Oya, Shizuoka 422-8529, Japan; tomohiroegusa@gmail.com
2 静冈大学农学部，日本静冈大野 422-8529;tomohiroegusa@gmail.com

3 Faculty of Agriculture/Agri-Innovation Center, Iwate University, Morioka 020-8550, Japan; hkoji@iwate-u.ac.jp
3 岩手大学农学部/农业创新中心，日本盛冈 020-8550;hkoji@iwate-u.ac.jp

* Correspondence: mathias.leiter@boku.ac.at
* 通信：mathias.leiter@boku.ac.at

Abstract: Domestic wood production in Japan is low, and more than 60% of the wood consumed is imported. This is surprising because two-thirds of Japan’s land area is covered by forests. The dominant explanations for this low wood self-sufficiency rate are the lack of forest road infrastructure and the small-scale forest ownership structure. Austria is a country that is similar in topography and ownership structure but has a high wood self-sufficiency rate. Therefore, previous research has compared Japan to Austria. However, these studies did not address basic forest properties in much detail. This study uses national forest inventory data from both countries to assess the forest structures and utilization percentages of the annual wood increment. In contrast to the hypothesis, the results show that the two countries have similar increment rates. In contrast to former studies, the findings indicate that Japanese plantation forests have a higher timber stocking volume than Austrian forests. In Japan, the proportion of the standing volume in the 40–60-year-old age class is much higher compared to the other age classes, indicating an unbalanced growing stock. The results show that the utilization percentage is much higher in Austria (88%) than in Japan (53%). Therefore, the Japanese forest sector has a high potential to increase the harvest of wood.
摘要： 日本国内木材产量低，60%以上的木材消费为进口木材。这是令人惊讶的，因为日本三分之二的土地面积被森林覆盖。木材自给率低的主要原因是缺乏林道基础设施和小规模的森林所有权结构。奥地利是一个地形和所有权结构相似的国家，但木材自给率很高。因此，以前的研究将日本与奥地利进行了比较。然而，这些研究并没有非常详细地讨论基本的森林特性。本研究使用两国的国家森林清查数据来评估森林结构和木材年增量的利用率。与假设相反，结果表明两国的增量率相似。与以前的研究相比，研究结果表明，日本人工林的木材储量高于奥地利森林。在日本，40-60岁年龄组的站立体积比例远高于其他年龄组，表明存量生长不平衡。结果表明，奥地利的利用率（88%）远高于日本（53%）。因此，日本的林业部门在增加木材采伐方面具有很大的潜力。

Keywords: national forest inventory; bioeconomy; age-class distribution; forest productivity; sustainability
关键词：国家森林清查;生物经济;年龄级分布;森林生产力;可持续性

1. Introduction
1. 引言

Japan and Austria are both mountainous countries with a high forest coverage, but their amount of harvested wood per hectare and forest structures differ greatly. Approxi- mately 25.6 million ha, almost two-thirds of Japan’s land area, is covered by forests, 42% of which (>10 million ha) are plantations [1]. More than half of these forests are located in areas with slopes greater than 15° [2]. Austria’s forests cover 4.4 million ha [3], 75% of which are located in steep areas [2].
日本和奥地利都是山地国家，森林覆盖率很高，但每公顷的采伐木材量和森林结构差异很大。约2560万公顷，几乎占日本土地面积的三分之二，被森林覆盖，其中42%（>1000万公顷）是种植园[1]。这些森林中有一半以上位于坡度大于15°的地区[2]。奥地利的森林面积为440万公顷[3]，其中75%位于陡峭地区[2]。

Because of the high demand for wood, large parts of Japan’s forests were harvested during and especially after the Second World War. This led to nationwide afforestation programs that peaked in 1953 and a second time in 1961 [4]. In the 1960s,the government liberalized wood imports to supply the growing economy. Foreign wood entered the Japanese market because it was much cheaper than domestic timber. With trade liberal- ization, the Japanese timber industry had to compete with the international wood market and as a result, the wood-self-sufficiency rate fell below 50% by 1969 for the first time in recent history [5]. After declining to 18.9% in 2000, the self-sufficiency rate increased to 34.8% in 2016 [6]. By 1980, local wood prices had declined to the point that many forest owners lost interest, and Japan fell into a “Forest Depression” [5]. This resulted in untended, unstable, and underutilized forests, and Japan became heavily dependent on wood imports. These unmanaged forests are no longer able to provide adequate protective, ecological, and
由于对木材的高需求，日本的大部分森林都是在第二次世界大战期间，尤其是之后被砍伐的。这导致了全国性的植树造林计划，在1953年达到顶峰，并在1961年第二次达到顶峰[4]。在 1960 年代，政府放宽了木材进口，以满足不断增长的经济需求。外国木材进入日本市场是因为它比国产木材便宜得多。随着贸易自由化，日本木材工业不得不与国际木材市场竞争，因此，到1969年，木材自给率在近代史上首次降至50%以下[5]。自给率在2000年下降到18.9%后，2016年上升到34.8%[6]。到1980年，当地木材价格已经下降到许多森林所有者失去兴趣的地步，日本陷入了“森林萧条”[5]。这导致了无人照料、不稳定和未充分利用的森林，日本严重依赖木材进口。这些未经管理的森林不再能够提供足够的保护、生态和

Forests 2022, 13, 891. https://doi.org/10.3390/f13060891 https://www.mdpi.com/journal/forests
森林 2022， 13， 891.https://doi.org/10.3390/f13060891https://www.mdpi.com/journal/forests

economical forest services [7,8]. Additionally, modern afforestation efforts suffer under the high density of sika deer (Cervus nippon), Japanese serow (Capricornis crispus), and other invasive mammals [7,9], leading to high levels of browsing and the dominance of tall grasses and weeds on clear-cut sites [9]. Today, the socio-economic challenges that Japan is facing include aging forest owners [10], forest owners leaving the countryside, and a reliance on national or local government subsidies in most parts of the forestry industry [11]. As a result, investment in forest management and forest infrastructure (e.g., forest roads) is low [1,12], and only 58% of the annual timber increment is currently harvested [13]. Thus, Kuboyama et al. [14] suggested that Japan can learn how to revitalize its forestry sector by looking at and learning from Austria.
经济型林业服务[7,8]。此外，现代植树造林工作受到梅花鹿（Cervus nippon）、日本羚羊（Capricornis crispus）和其他入侵哺乳动物的高密度影响[7,9]，导致高水平浏览和高草和杂草在砍伐地点占主导地位[9]。今天，日本面临的社会经济挑战包括森林所有者老龄化[10]，森林所有者离开农村，以及林业大部分地区对国家或地方政府补贴的依赖[11]。因此，对森林管理和森林基础设施（如林道）的投资较低[1,12]，目前仅采伐了58%的年度木材增量[13]。因此，Kuboyama等[14]建议日本可以通过学习和学习奥地利来学习如何振兴其林业部门。

In 2015, Austrian forest owners harvested 26 million m3, or 88% of the annual timber increment [3]. Austria has a long history of sustainable forest management [3]. Austrian forestry is based on the concept of “careful forest utilization”, which was introduced at the beginning of the 19th century. This concept emerged after years of destructive logging to sustain theiron and salt industries as well as to accommodate growing metropolitan areas [15].
2015年，奥地利森林所有者采伐了2600万m3，占年度木材增量的88%[3]。奥地利在可持续森林管理方面有着悠久的历史[3]。奥地利林业基于19世纪初引入的“谨慎利用森林”的概念。这个概念是在多年的破坏性伐木之后出现的，以维持铁和盐工业以及适应不断增长的大都市地区[15]。

Although Austria and Japan have mainly mountainous forests [2] with a similar, small-scale forest ownership structure [1], the two countries show different trends in their wood production. Thus, understanding the bio-geophysical and socio-economic reasons for these diverging trends is important for assessing the potential future development of the forest sector, including the carbon sequestration potential for the two countries. This section briefly reviews Japanese studies that compare Austria and Japan by addressing the differences in forest road density [14,16–19] and differences in the average stocking volume: (1) Austria has a forest road density of 45 m/ha versus Japan with only 14 m/ha [14,17]; (2) the average stocking volume with 325 m3 /hain Austrian is much higher than in Japanese plantation forests with only 256 m3 /ha [14]. Higher volume-per-hectare values indicate a higher volume per single tree, which will result in lower harvesting costsper m3 . This so-called “law of mass per piece” [20] leads to lower average harvesting costs per m3 in Austria compared to Japan. In addition, Austria was able to develop a very efficient and economically successful forest and timber supply chain industry, which is lacking in Japan [1,14].
尽管奥地利和日本的山地森林[2]和小规模森林所有权结构相似[1]，但两国的木材生产趋势不同。因此，了解造成这些不同趋势的生物地球物理和社会经济原因对于评估森林部门未来的潜在发展，包括两国的碳封存潜力非常重要。本节简要回顾了比较奥地利和日本的日本研究，讨论了森林道路密度的差异[14,16\u201219]和平均放养量的差异：（1）奥地利的森林道路密度为45米/公顷，而日本只有14米/公顷[14,17];（2）奥地利人工林的平均放养量为325 m3/hain，远高于日本人工林的256 m3/ha[14]。每公顷体积值越高，表示每棵树的体积越大，这将导致每立方米的采伐成本降低。与日本相比，这种所谓的“每件质量定律”[20]导致奥地利每立方米的平均收获成本较低。此外，奥地利能够发展出非常高效且经济成功的森林和木材供应链产业，这是日本所缺乏的[1,14]。

These studies compared a few of the basic forest properties of the two countries. For example, Kuboyama et al. [14] compared the volume per hectare but did not compare increment rates or age class distribution. The differences in environmental factors, especially the mean, maximum, and minimum annual temperature and summer precipitation [21], may result in significantly different increment rates. The hypothesis is that the forests in Austria and Japan differed in the age-class distribution, increments rates, and the harvesting intensities. Thus, the potential differences in the increment rates, in combination with the differences in age-class distribution by country, may result in diverging forest resource potentials between Austria and Japan.
这些研究比较了两国的一些基本森林特性。例如，Kuboyama等[14]比较了每公顷的体积，但没有比较增量率或年龄级分布。环境因子的差异，特别是年平均、最高、最低气温和夏季降水量[21]，可能导致显著的增量速率。假设奥地利和日本的森林在年龄等级分布、增量率和采伐强度方面存在差异。因此，增量率的潜在差异，加上各国年龄级分布的差异，可能导致奥地利和日本之间的森林资源潜力存在差异。

The purpose of this study was to investigate: (1) the forest area, the growing stock, and age-class distribution; (2) historic changes in the forest area, volume, harvest, and utilization percentage; and (3) the increment rates per age class and the related sustainable harvesting potential of major tree species within each country to enhance our understanding of why
本研究旨在调查：（1）森林面积、生长存量和年龄级分布;（2）森林面积、数量、采伐量和利用率的历史变化;（3）每个年龄组的增量率以及每个国家内主要树种的相关可持续采伐潜力，以增强我们对原因的理解

the development of the forest sector differs between Japan and Austria.
日本和奥地利的林业发展情况各不相同。

2. Materials and Methods
2. 材料与方法

2.1. Data
2.1. 数据

The data for this study were obtained from the Japanese and Austrian national forest
本研究的数据来自日本和奥地利的国家森林

inventories and national forestry reports [3,6,13]; demand and supply information was provided by the national forest and energy agencies of each country [3,13,22].
清单和国家林业报告[3,6,13];供需信息由各国国家林业和能源机构提供[3,13,22]。

The Japanese National Forest Inventory (JNFI) was introduced in 1999 andis organized into two parts: (1) a forest resource monitoring survey and (2) a forest planning system [12]. The forest resource monitoring survey uses a sampling system [23]. The sampling plots
日本国家森林清查（JNFI）于1999年推出，分为两部分：（1）森林资源监测调查和（2）森林规划系统[12]。森林资源监测调查使用抽样系统[23]。采样图

are established on a 4 km × 4 km grid across the country, with a total of 23,600 plots. The forest or non-forest status is determined via aerial photographs, which reduces the number to approximately 16,000 forest plots [24]. Because of accessibility issues, the number of measured plots is further reduced to 13,357 [25]. The plots are 0.1 hain size and consist of three circular-shaped subplots with different radii (5.64 m, 11.28 m, and 17.84 m) at the same center point. The measured diameters at breast height (DBHs) are ≥1 cm in the smallest circle, ≥5 cm in the middle circle, and >18 cm in the largest circle [12]. In most countries, DBH is measured at 1.3 m height from the ground, but it is measured at 1.2 m height in Japan [26]. The trees on the plot are numbered, and the tree height,DBH, and the number of dead trees are recorded. In the second step (the forest planning system), forest registers and planning maps are created. A forest register includes forest stand information, such as DBH, tree species, age, forest type, and ownership structure. The standing volume is calculated using yield tables [12] which differ by forest ownership type. Additionally, all 47 prefectural governments have their own locally adapted yield tables [25]. The stand and yield table data are then combined with images and used to create a geographic information system that contains all the important forest stand information and ownership boundaries [12,23]. The JNFI measures multiple plot parameters, such as site and stand information and dominant species. Age information comes from the forest register, which also covers regeneration information. Shrub and herb layers, including their coverage, are determined according to [12,27].
在全国4公里×4公里的网格上建立，共有23,600个地块。森林或非森林状态是通过航空照片确定的，这将数量减少到大约16,000个森林地块[24]。由于可访问性问题，测量地块的数量进一步减少到13,357个[25]。这些样地的大小为 0.1 hain，由三个位于同一中心点的不同半径（5.64 m、11.28 m 和 17.84 m）的圆形子样地组成。测量的胸高直径（DBHs）在最小圆圈中为≥1 cm，在中间圆圈中为≥5 cm，在最大圆圈中为>18 cm[12]。在大多数国家，胸径是在距地面1.3 m高度处测量的，但在日本，胸径是在1.2 m高度处测量的[26]。对地块上的树木进行编号，并记录树高、胸径和死树数量。在第二步（森林规划系统）中，创建森林登记册和规划地图。森林登记册包括林分信息，如胸径、树种、年龄、森林类型和所有权结构。林分体积是使用产量表[12]计算的，该表因森林所有权类型而异。此外，所有47个都道府县都有自己的因地制宜的产量表[25]。然后将林分和产量表数据与图像相结合，用于创建包含所有重要林分信息和所有权边界的地理信息系统[12\u2012223]。JNFI测量多个样地参数，如地点和林分信息以及优势物种。年龄信息来自森林登记册，其中也包括再生信息。灌木和草本层，包括它们的覆盖率，根据[12\u2012227]确定。

The Austrian National Forest Inventory (ANFI) was introduced in 1961 [3]. Today, it is based on a systematic, permanent, hidden, nationwide grid design of 3.89 km × 3.89 km with a cluster of four inventory plots at each grid point (approximately 22,000 plots and 5500 clusters). Each cluster is a square (200 m × 200 m) with a plot in each corner. The permanent plots were established from 1981 to 1985 by setting up 20% of the inventory points per year. Each inventory plot is marked with a hidden iron stick [28] which was placed at the site at the beginning of the inventory process. The iron stick is hidden to eliminate the research plot bias [29] and ensures that the forest inventory is representative of the growing conditions and forest management throughout Austria. The condition of the forest was measured at each plot by using an angle count sample plot [30] and a basal area factor of 4 m2/ha for trees with a DBH ≥ 10.4 cm; a fixed area plot (r = 2.6 m, area = 21.2 m2) was used for trees with DBHs ranging from 5.0 to 10.4 cm. For a detailed description of the ANFI, please refer to Schieler [31] for increment calculations and to Gabler and Schadauer [32] for
奥地利国家森林清单（ANFI）于1961年推出[3]。今天，它基于3.89公里×3.89公里的系统、永久、隐藏的全国性网格设计，每个网格点有四个库存地块（大约22,000个地块和5500个集群）。每个集群都是一个正方形（200 m × 200 m），每个角落都有一个地块。从1981年到1985年，通过每年建立20%的库存点来建立永久地块。每个库存地块都标有一根隐藏的铁棍[28]，该铁棍在库存过程开始时放置在现场。铁棒被隐藏起来，以消除研究地块偏差[29]，并确保森林清单代表整个奥地利的生长条件和森林管理。使用角度计数样地[30]测量每个样地的森林状况，对于胸径≥10.4 cm的树木，基底面积因子为4 m2/ha;固定面积图（R = 2.6 m，面积 = 21.2 m2）用于胸径范围为 5.0 至 10.4 cm 的树木。有关ANFI的详细说明，请参阅Schieler [31]进行增量计算，并参考Gabler和Schadauer [32] 进行增量计算

sample design and field instructions.
样品设计和现场说明。

2.2. Method
2.2. 方法

For Austria, the ANFI 6 plotdata recorded in 2000–2002, ANFI 7 plotdata recorded in 2007–2009, as well as the ANFI 8 plot data recorded in 2016–2018, resulting in a re- measurement interval of 7–9 years [32], were used. For Japan, the JNFI second-stage plot data recorded in 2004–2008, and JNFI third-stage plotdata recorded in 2009–2013, resulting in a re-measurement interval of 4–6 years, were used. For historic data, this study relied on information provided by the respective national ministries and agencies [3,6,13,33]. Japanese data from before 1999 are based on national forest register data that relied on yield tables and not on time series of field measurements. Consequently, historic Japanese data might not be as accurate as data from 1999 onward.
奥地利使用2000-2002年记录的ANFI 6图数据、2007-2009年记录的ANFI 7图数据以及2016-2018年记录的ANFI 8图数据，重新测量间隔为7-9年[32]。对于日本，使用了 2004-2008 年记录的 JNFI 第二阶段图数据和 2009-2013 年记录的 JNFI 第三阶段图数据，导致重新测量间隔为 4-6 年。对于历史数据，本研究依赖于各国部委和机构提供的信息[3,6,13,33]。日本1999年以前的数据是以国家森林登记数据为依据的，这些数据依赖于产量表，而不是实地测量的时间序列。因此，日本的历史数据可能不如1999年以后的数据准确。

With these data, the forest area, forest area changes, standing volume, and standing volume changes were calculated for each country. For the changes in standing volume, the forests were split into hardwoods and softwoods to highlight which type of forest is contributing the most to total volume change. The annual increment rates are derived by comparing the volume of each plot in the second-stage JNFI and the third-stage JNFI data. The plot-based increment rates for Austria are taken from ANFI 6. Some JNFI points did not include all the parameters mentioned in the data section. Because of this lack of data, some points were excluded when calculating the increment rates. To calculate the increment, only plots for which volume had been measured twice (i.e., in the second and
根据这些数据，计算了每个国家的森林面积、森林面积变化、林分体积和林分体积变化。对于林分体积的变化，将森林分为硬木和软木，以突出哪种类型的森林对总体积变化的贡献最大。通过比较第二阶段 JNFI 和第三阶段 JNFI 数据中每个地块的体积，得出了年增量率。奥地利基于绘图的增量率取自 ANFI 6。一些JNFI点不包括数据部分中提到的所有参数。由于缺乏数据，在计算增量率时排除了一些点。要计算增量，仅测量体积两次的图（即，在第二次和

third stages of JNFI) were used. This resulted in the use of 9880 points out of 14,470. For Japan,the dominant tree species is defined by the national forest agency as the tree species that contributes more than 30% of the plot’s basal area. For Austria, this study defined the dominant tree species for each plot by using the tree species that contributes the most to the basal area in the plot. Most of the calculations are carried out in R Statistical Software v4.1.2. [34]. Figures were made with the software package ggplot2 v3.3.5 [35].
JNFI）的第三阶段）。这导致使用了 9880 分中的 14,470 分。对于日本来说，国家林业厅将优势树种定义为占地块基础面积30%以上的树种。对于奥地利，本研究通过使用对样地基底面积贡献最大的树种来定义每个样地的优势树种。大多数计算是在 R Statistical Software v4.1.2 中执行的。[34]. 使用软件包 ggplot2 v3.3.5 [35] 制作图。

3. Results
3. 结果

3.1. Dominant Tree Species
3.1. 优势树种

Japanese forests have two major softwood species, Japanese cedar (Cryptomerica japon- ica L.f.) and Japanese cypress (Chamaecyparis obtusa Siebold and Zucc.), also called sugi and hinoki, respectively. These two species cover large parts of the forest area and cover more than 50% of the national stocking volume (Table 1). Cryptomerica japonica is the most planted species because it exhibits higher annual increment rates than C. obtusa, and has a higher tol- erance for cold temperatures [36]. As shown in Figure 1, hardwoods are very rarely planted. The most common naturally regenerating hardwood species are Quercus serrata Murray and Fagus crenata Blume. The most commonly planted species in the mountainous central region of Honshu, sometimes called the Japanese Alps, is Japanese larch (Larix kaempferi Lamb.), also known as karamatsu. Larix kaempferi stands replaced Japanese red pine (Pinus densifloraSiebold), which were damaged by pine wilt diseases [37,38]. On the northern island of Hokkaido, the coldest and snowiest part of Japan, Sakhalin fir (Abies sachalinensis F.Schmidt), L. kaempferi, and Sakhalin spruce Picea glenhii are the most commonly planted tree species.
日本森林有两种主要的针叶木树种，日本雪松（Cryptomerica apon- ica L.f.）和日本柏树（Chamaecyparis obtusa Siebold 和 Zucc.），分别也称为杉木和桧木。这两个物种覆盖了大部分森林面积，占全国放养量的50%以上（表1）。日本隐花（Cryptomerica japonica）是种植最多的树种，因为它的年增量比钝柳（C. obtusa）高，并且对低温的耐受性更高[36]。如图 1 所示，硬木很少种植。最常见的自然再生硬木树种是锯齿栎（Quercus serrata Murray）和法古斯·克雷纳塔·布鲁姆（Fagus crenata Blume）。在本州中部山区（有时被称为日本阿尔卑斯山）最常见的种植物种是日本落叶松（落叶松羊），也称为卡拉松。落叶松取代了因松枯萎病而受损的日本红松（Pinus densifloraSiebold）[37\u201238]。在日本最寒冷和积雪最多的北海道北部岛屿上，库页岛冷杉（Abies sachalinensis F.Schmidt）、山泉杉和库页岛云杉云杉 Picea glenhii 是最常见的种植树种。

Table 1. Tree species and their respective percentage of the total national standing volume. Data are from the Austrian National Forest Inventory (2018) and Japanese National Forest Inventory (2013).
表 1.树种及其各自占全国总立面积的百分比。数据来自奥地利国家森林清查（2018年）和日本国家森林清查（2013年）。

Figure 1. Dominant tree species in plantation forests in Japan. Jittering was applied to the points to reduce overlapping. Other hardwood species and softwood species were pooled into “hardwoods” and “softwoods” . The sizes of the circles show the approximate mean annual increment per plot. Data are from the Japanese National Forest Inventory (2013). The red triangle indicates Tokyo.
图 1.日本人工林中的优势树种。对点施加抖动以减少重叠。其他阔叶木树种和软木树种被合并为“阔叶木”和“软木”，圆圈的大小显示了每个地块的近似平均年增量。数据来自日本国家森林清查（2013年）。红色三角形表示东京。

Within Austrian forests, 60.4 % of the standing volume consists of Norway spruce (Picea abies (L.) H.Karst) (Table1). Picea abies dominates large parts of the country, especially the mountainous regions of western and central Austria (Figure 2). Some stands dominated by European larch (Larix decidua Mill.) can be found in sub-alpine areas. Forests dominated by silver fir (Abies alba Mill.) can be found in northern Tyrol, a western Austrian province. Hardwoods grow on the southern and northern edges of the European Alps in the northeast and southeast of Austria. The Viennese Forest next to the city of Vienna mainly consists of European beech (Fagus sylvatica L.). Pinus spp. stands dominate southeastern Austria. Oaks (Quercus spp.) are the dominant tree species in northeastern Austria.
在奥地利森林中，60.4%的林立体积由挪威云杉（Picea abies （L.） H.Karst）组成（表1）。云杉在该国大部分地区占主导地位，尤其是奥地利西部和中部的山区（图2）。在亚高山地区可以找到一些以欧洲落叶松（落叶松）为主的林分。以银杉（Abies alba Mill.）为主的森林分布在奥地利西部的蒂罗尔省北部。硬木生长在奥地利东北部和东南部的欧洲阿尔卑斯山的南部和北部边缘。维也纳市旁边的维也纳森林主要由欧洲山毛榉（Fagus sylvatica L.）组成。松属林分在奥地利东南部占主导地位。橡树（Quercus spp.）是奥地利东北部的主要树种。

Figure 2. Dominant species in Austria. Jittering was applied to the points to reduce overlapping. Other hardwood species and softwood species were pooled into “hardwoods” and “softwoods” . The sizes of the circles show the approximate mean annual increment per plot. Data are from the Austrian National Forest Inventory (2009). The red triangle indicates Vienna.
图2.奥地利的优势种。对点施加抖动以减少重叠。其他硬木树种和软木树种被合并为“硬木”和“软木”。圆圈的大小显示每个图的近似平均年增量。数据来自奥地利国家森林清查（2009年）。红色三角形表示维也纳。

3.2. Current Forest Conditions and Historic Development
3.2. 当前的森林状况和历史发展

Japanese forests cover approximately 25 million ha, two-thirds of the national land area. In Austria, forests cover about 4 million ha, nearly half of the national land area. The current forest area in Austria has increased by 4% (Figure 3) compared to the forest area in 1970. In Japan, the forest area has declined by less than 1% (Figure 3) compared to the forest area in 1970.
日本森林面积约2500万公顷，占国土面积的三分之二。在奥地利，森林面积约为400万公顷，几乎占全国土地面积的一半。与1970年的森林面积相比，奥地利目前的森林面积增加了4%（图3）。与1970年的森林面积相比，日本的森林面积减少了不到1%（图3）。

Figure 3. Change in forest area since 1970 according to data from the Austrian National Forest Inventory (2018), BMLFUW (2015), and Forest Agency (2017).
图3.根据奥地利国家森林清单（2018 年）、BMLFUW（2015 年）和林业局（2017 年）的数据，自 1970 年以来森林面积的变化。

The total standing volume has increased in both countries since the 1990s. In Austria, the total volume has changed from 0.99 billion m3 in 1996 to 1.17 billion m3 in 2016. In Japan, the volume has increased from 3.14 billion m3 in 1990 to 4.9 billion m3 in 2012, because of a large increase in softwood volume from 2.01 billion m3 to 3.46 billion m3 (Figure 4a) [6]. Softwood and hardwood have increased in both countries, but with some interesting differences: in Japan, softwood has increased by more than 40%,whereas in Austria, hardwood has increased by more than 40% (Figure 4b). The median volume per hectare is 393 m3/hain Japanese plantation forest and 281 m3 /hain Austrian forests.
自1990年代以来，这两个国家的总站立量都有所增加。在奥地利，总体积从1996年的9.9亿m3变化到2016年的11.7亿m3。在日本，由于针叶木的体积从20.1亿m3大幅增加到34.6亿m3，体积从1990年的31.4亿m3增加到2012年的49亿m3（图4a）[6]。这两个国家的软木和硬木都有所增加，但有一些有趣的差异：在日本，软木增加了40%以上，而在奥地利，硬木增加了40%以上（图4b）。日本人工林每公顷的中位体积为393 m3/ha，奥地利人工林为281 m3/ha。

(a) (b)
（一）（二）

Figure 4. Total volume (a) and volume change since 1995 (Japan) and 1996 (Austria) (b) of hardwoods and softwoods according to data from the Austrian National Forest Inventory (1996, 2002, 2009, 2018) and Forest Agency (2019b).
图4.根据奥地利国家森林名查（1996年、2002年、2009年、2018年）和林业局（2019b）的数据，自1995年（日本）和1996年（奥地利）以来，硬木和软木的总产量（a）和体积变化（b）。

The total annual harvest in Japan declined from 50 million m3 in 1965 to 17 million m3 in 2005, resulting in a severe decline in the wood self-sufficiency rate. In 2005, only 20.5% of the demanded wood resources were produced in Japan, leading to the second-lowest self-sufficiency rate in Japan’s history after the 18.9% recorded in 2000 [6]. In Austria, the harvests increased from 9.6 million m3 in 1975 to nearly 20.9 million m3 in 2016 (Figure 5a). In 2018, the Austrian harvest-to-increment rate reached 88%, while in Japan, the harvest-to- increment rate declined after the late 1980s from approximately 54% to 32% in 2001, and increased to approximately 58% in 2011 (Figure 5b).
日本的年总采伐量从1965年的5000万m3下降到2005年的1700万m3，导致木材自给率严重下降。2005年，日本生产的木材资源仅占需求量的20.5%，自给率仅次于2000年的18.9%，是日本历史上第二低的[6]。在奥地利，收成从1975年的960万m3增加到2016年的近2090万m3（图5a）。2018年，奥地利的收获增量率达到88%，而日本的收获增量率在1980年代后期后从约54%下降到2001年的32%，2011年上升到约58%（图5b）。

(a) (b)
（一）（二）

Figure 5. The total harvest (a) and forest utilization percentage (harvest divided by increment) (b) according to data from the Austrian National Forest Inventory (1996, 2002, 2009, 2018) and Forest
图5.根据奥地利国家森林清查（1996年、2002年、2009年、2018年）和森林的数据，总采伐量（a）和森林利用百分比（采伐量除以增量）（b）

Agency (2019a, 2019b).
机构（2019a，2019b）。

3.3. Volume Increment
3.3. 体积增量

As shown in Figure 6, the mean annual increment by age class in Austria ranges from 10.6 m3ha–1year–1 for the 10–20-year age class to 3.4 m3ha–1year–1 for the 141+-year age class. It peaks at 13.4 m3ha–1year–1 for the 21–40-year age class. In Japan, the lowest incre- ment was 6.4 m3ha–1year–1 at 0–20 years (not shown in Figure 6). The increment peaked at 11.5 m3ha–1year–1 in the 21–40-year age class, the same as in Austria. The standard deviations in Japan ranged from 12.7 to 22.6 m3ha–1year–1, whereas in Austria, they ranged from 4 to 9 m3ha–1year–1 . A Welch two-sample t-test revealed that the increment rates according to age class did not significantly differ by country, except for the age classes of 81–100 and 141+. In Japan, the lowest increment rates can be found in Hokkaido, as
如图 6 所示，奥地利按年龄等级划分的平均年增量范围从 10.6-10 岁年龄组的 10.3 m3ha-1year-1 到 3.4+ 岁年龄组的 1 m3ha-1year-141。对于21-40岁年龄组，它的峰值为13.4 m3ha-1year-1。在日本，0-20年最低的增幅为6.4 m3ha-1-1年-1（图6未显示）。在21-40岁年龄组中，增量达到11.5 m3ha-1year-1的峰值，与奥地利相同。日本的标准差范围为12.7至22.6 m3ha-1year-1，而在奥地利，标准差范围为4至9 m3ha-1year-1。Welch 双样本 t 检验显示，除了 81-100 和 141+ 的年龄组外，不同年龄等级的增量率在不同国家之间没有显着差异。在日本，北海道的增量率最低，如

well as in the Kitakami highlands in northeast Honshu (Figure 1). In Austria, the lowest increments rates can be found in northeastern Austria and in subalpine areas (Figure 2).
以及本州东北部的北上高地（图1）。在奥地利，奥地利东北部和亚高山地区的增量率最低（图2）。

Figure 6. Increment according to age class. Mean increments were tested (Welch two-sample t-test) for significant differences in the same age class between Austria and Japan (NS: p > 0.05, ** p ≤ 0.01, *** p ≤ 0.001). Trees younger than 10 years old were excluded because DBHs smaller than 5 cm are not measured in the ANFI. The black line that divides the box into two parts represents the median. The ends of the box show the lower (bottom) and upper (top) quartiles. The vertical lines show the lowest and highest values, excluding potential outliers. Data are from the Austrian National Forest Inventory (2002, 2009) and Japanese National Forest Inventory (2007, 2011).
图6.根据年龄等级递增。检验了奥地利和日本之间同一年龄组的显著差异（Welch 双样本 t 检验）的平均增量（Welch 双样本 t 检验）（NS：p > 0.05，** p ≤ 0.01，*** p ≤ 0.001）。10 岁以下的树木被排除在外，因为 ANFI 中没有测量小于 5 厘米的胸径。将盒子分成两部分的黑线表示中位数。框的末端显示下（下）和上（上）四分位数。垂直线显示最低值和最高值，不包括潜在的异常值。数据来自奥地利国家森林清查（2002年、2009年）和日本国家森林清查（2007年、2011年）。

3.4. Age-Class Distribution
3.4. 年龄级分布

We then compared Japanese planted forests, which contain 59% of the total forest volume and cover 44% of the forest area with the Austrian “Ertragswald”,which indicates the intensively managed forest area and covers 80% of the Austrian forest area. Figure 7a shows the distribution of forest area by age classes for Japanese plantations and Austrian Ertragswald.
然后，我们将占总森林体积的59%，覆盖森林面积44%的日本人造林与奥地利的“Ertragswald”进行了比较，后者表示集约化管理的森林面积，覆盖了奥地利森林面积的80%。图7a显示了日本人工林和奥地利埃特拉格斯瓦尔德的森林面积分布情况。

(a) (b)
（一）（二）

Figure 7. Percentage of forest area (planted forests and Ertragswald) according to age class (a) and the percentage of volume of all forests according to age class (b). Dotted lines in (a) show the perfect distribution for Cryptomeria japonica in Japan and Picea abies in Austria. Data are from the Austrian National Forest Inventory (2018) and Japanese National Forest Inventory (2013).
图7.按年龄等级（a）分列的森林面积（人工林和埃特拉格斯瓦尔德林）的百分比，以及按年龄等级（b）分列的所有森林的体积百分比。（a）中的虚线显示了日本的Cryptomeria japonica和奥地利的Picea abies的完美分布。数据来自奥地利国家森林清查（2018年）和日本国家森林清查（2013年）。

The dominant age class of the Japanese plantation forests is 41–60 years, with more than 4 million ha. This age class covers approximately 50% of the total standing timber volume (Figure 7b), which is nearly 3 billion m3 . In Austria, the 41–60-year age class is also dominant, but only covers 20% of the total Austrian standing volume (Figure 7b). This
日本人工林的主要年龄等级是41-60岁，面积超过400万公顷。这个年龄等级约占活立木总体积的50%（图7b），接近30亿m3。在奥地利，41-60岁年龄组也占主导地位，但仅占奥地利总站立体积的20%（图7b）。这

suggests that, compared to Japan, Austrian forests have a much more balanced age-class distribution, which ensures more sustainable harvesting options.
这表明，与日本相比，奥地利森林的年龄级分布更加均衡，这确保了更可持续的采伐选择。

3.5. Wood Demand and Supply
3.5. 木材需求和供应

In 2018, the demand for wood in Japan reached 82.5 million m3 . Domestic production was only 30.2 million m3; 52.3 million m3 were imported while 2.8 million m3 were exported. Most of the imported wood was in the form of wood products, such as wood chips (21.4 million m3) and sawn wood (9.4 million m3) [13]. The domestic production of wood in Austria reached 25.5 million m3 in 2018, and a total of 12.8 million m3 was imported in the same year. Most of the imported wood consisted of sawlogs (7.5 million m3) to sustain the large Austrian sawmill industry. In 2018, the sawmill industry demanded 20.6 million m3, 6.1 million m3 of which were exported as sawn wood [22]. In Japan,
2018年，日本对木材的需求达到8250万m3。国内产量仅为3020万m3;进口5230万m3，出口280万m3。大多数进口木材以木制品的形式出现，例如木屑（2140万m3）和锯材（940万m3）[13]。2018年奥地利国内木材产量达到2550万m3，同年进口总量为1280万m3。大部分进口木材由锯木组成（750 万立方米），以维持奥地利大型锯木厂的工业。2018年，锯木厂行业需要2060万m3，其中610万m3作为锯材出口[22]。在日本，

4993 sawmills produced 9.2 million m3 sawn wood in 2015 [1]. In Austria, 1000 sawmills
2015年，4993家锯木厂生产了920万m3锯材[1]。在奥地利，有 1000 家锯木厂

produced 10.4 million m3 sawn wood in 2018 [22].
2018年生产了1040万m3锯材[22]。

4. Discussion
4. 讨论

Japan and Austria have a forest coverage of approximately 66% and 50%, respectively. Since 1970, the forest area has increased in Austria and remained relatively constant in Japan (Figure 3). Both countries have exhibited an increase in total stock, but there are distinct differences by country in the development of the stocking volume of hardwood versus softwood (Figure 4). In Austria,the increase in hardwood has resulted from the fact that sites formerly planted with softwood (P. abies) naturally regenerate with hardwoods, mainly F. sylvatica. In Japan, softwoods have increased, because the growth rates of softwood species are higher than those of hardwood species and harvesting intensity has been low (Figure 5). For example, the harvest in Japan has dropped since 1960 to a current utilization ratio (increment divided by harvest) of only 58% (Figure 5), whereas the Austrian forestry sector has continuously increased the utilization rate to more than 80%, primarily due to large investments in forest infrastructure, education, and support to promote forest management [3]. Harvesting operations in both countries are sustainable, as both utilization percentages are below 100%.
日本和奥地利的森林覆盖率分别约为66%和50%。自1970年以来，奥地利的森林面积有所增加，而日本的森林面积保持相对稳定（图3）。这两个国家的总库存量都有所增加，但各国在硬木和软木的库存量方面存在明显差异（图4）。在奥地利，硬木的增加是由于以前种植软木（P. abies）的地点自然再生硬木，主要是F. sylvatica。在日本，由于针叶木树种的生长速度高于阔叶木树种，而且采伐强度较低，因此针叶木有所增加（图5）。例如，自1960年以来，日本的采伐量下降到目前的利用率（增量除以收获量）仅为58%（图5），而奥地利林业部门的利用率不断提高到80%以上，这主要是由于对森林基础设施、教育和促进森林管理的支持进行了大量投资[3]。这两个国家的采伐作业都是可持续的，因为这两个国家的利用率都低于100%。

Japanese and Austrian forests are mainly located in mountainous regions, but they are indistinct climatic regions. One of the interesting questions of our study was whether there are any differences in the increment rates of Japan’s forests and the Austrian “Ertragswald” . As shown in Figure 6, the mean increment rates by age class are similar, which was surprising. Thus,low growth rates cannot be the reason for a low wood self-sufficiency rate in Japan. The median stocking volume per hectare in Japanese plantation forest is 28% higher than the stocking volume in the Austrian “Ertragswald” . These results are in contrast with the findings of Kuboyama et al. [14]. These suggested that the stocking volume per hectare in Austria is 21% higher than that in Japanese plantation forests. The different results may be explained by the fact that Kuboyama et al. [14] relied on forest resource data from the 2008 Annual Report on Trends in Forest and Forestry in Japan. Since then, high increments and low utilization percentage led to an increase in forest volume (Figure 4a).
日本和奥地利的森林主要位于山区，但它们是模糊的气候区域。我们研究的一个有趣的问题是，日本森林和奥地利“埃特拉格斯瓦尔德”的增量率是否存在任何差异。如图 6 所示，各年龄组的平均增量率相似，这令人惊讶。因此，低增长率不能成为日本木材自给率低的原因。日本人工林每公顷的放养量中位数比奥地利“埃特拉格斯瓦尔德”的放养量高28%。这些结果与Kuboyama等[14]的研究结果形成鲜明对比。这表明奥地利每公顷的放养量比日本人工林高出21%。Kuboyama等[14]依赖于2008年《日本森林和林业趋势年度报告》中的森林资源数据，可以解释不同的结果。从那时起，高增量和低利用率导致森林体积增加（图4a）。

The main commercial tree species in Austria (P. abies; Table1) naturally regenerates, whereas C. japonica, the main species in Japan, does not [39]. The second most planted species in Japan (C. obtusa) barely regenerates under the canopy and prefers mineralsoils and small gaps [40]. These ecological conditions led to a segregation between planted and natural forests in Japan, which did not happen in Austria, where major commercial tree species naturally regenerate.
奥地利的主要商业树种（P. abies;表1）自然再生，而日本的主要物种C. japonica则不会[39]。日本第二大种植物种（C. obtusa）在树冠下几乎不再生，更喜欢矿物土壤和小缝隙[40]。这些生态条件导致了日本人工林和天然林之间的隔离，这在奥地利没有发生，因为奥地利的主要商业树种自然再生。

In Japan, only 58% of the current annual increment (Figure 5b) is harvested. Austrian forest owners harvest 88% of the annual increment. This suggests that the forest sector in Japan has a very high harvesting potential. Increasing the harvest rate could increase the country’s self-sufficiency regarding wood, which would also create additional income for local farmers and forest companies. The growth rates for Japan were estimated with
在日本，目前每年增量的58%（图5b）被收获。奥地利森林所有者的采伐量占年增量的 88%。这表明日本的森林部门具有非常高的采伐潜力。提高采伐率可以提高该国木材的自给自足，这也将为当地农民和林业公司创造额外收入。日本的增长率估计为

empirical models by the Japanese Forestry Agency and might be underestimated [25]. Thus, the harvesting potential could be even higher.
日本林业厅的经验模型，可能被低估了[25]。因此，收获潜力可能更高。

Within the next decade, the main silvicultural challenge within the Japanese forest sector is to achieve a balanced age structure within the forest plantations to ensure a sustained supply of forest products to the Japanese wood market, similar to that in Austria (Figure 7a). The unbalanced age-class distribution comes from large-scale afforestation efforts in the 1950s [4], with the result of more than 50% of the plantations being older than 50 years old (Figure 7b). These stands are ready to be harvested since they have reached the expected rotation length. Additional problems are that some of these forest areas lack accessibility for harvesting [8] due to the low forest road density [14,18] and that an increasing number of forest owners do not have adequate forest management knowledge [8]. Thus, further studies and initiatives within the Japanese forest sector are needed to enhance sustainable forest management by better understanding the ownership structure and
在未来十年内，日本森林部门的主要造林挑战是在人工林内实现平衡的年龄结构，以确保向日本木材市场持续供应林产品，类似于奥地利（图7a）。1950年代的大规模植树造林工作[4]导致了年龄级分布的不平衡，结果超过50%的人工林树龄超过50年（图7b）。这些林分已达到预期的轮作长度，因此可以收获。其他问题是，由于森林道路密度低，其中一些森林地区缺乏采伐的可达性[8]，并且越来越多的森林所有者没有足够的森林管理知识[8]。因此，需要在日本森林部门开展进一步的研究和采取主动行动，通过更好地了解所有权结构和

developing forest road systems to provide up-to-date mechanized harvesting systems.
开发森林道路系统，以提供最新的机械化采伐系统。

5. Conclusions
5. 结论

This study shows that Japanese forests store a large number of forest resources which would be accessible for harvesting in the near future. Annual wood increments do not significantly differ between Austria and Japan, but Austria utilizes a higher percentage of this increment. This results in a higher wood self-sufficiency rate in Austria. In Japan, ac- tions are needed to avoid risks from over-aging stands, but also to continuously regenerate aging stands to achieve a balanced age structure. This will require investments and efforts in silvicultural management practices, infrastructure, and education, but it should result in a boost for the Japanese forest and timber industry by creating jobs and income and will increase the wood self-sufficiency rate of Japan.
这项研究表明，日本的森林储存了大量的森林资源，这些资源在不久的将来可以采伐。奥地利和日本的木材年增量没有显着差异，但奥地利利用这一增量的百分比更高。这导致奥地利的木材自给率更高。在日本，既要避免林分过度老化带来的风险，又要不断更新老化的林分，以实现平衡的年龄结构。这将需要在造林管理实践、基础设施和教育方面进行投资和努力，但它应该通过创造就业机会和收入来促进日本的森林和木材工业，并将提高日本的木材自给率。

Author Contributions: Conceptualization, M.L., M.N. and H.H.; formal analysis, M.L., M.N. and T.E.; investigation, M.L., K.H., M.N. and T.E.; methodology, M.L. and M.N.; resources, T.E. and M.N.; software, M.L.; validation: M.N. and T.E., data curation, T.E., M.N., K.H. and M.L.; writing—original draft preparation, M.L.; writing—review and editing, M.N., T.E., K.H. and H.H.; visualization, M.L.; supervision, H.H. All authors have read and agreed to the published version of the manuscript.
作者贡献：概念化、M.L.、M.N. 和 H.H.;形式分析，M.L.、M.N. 和 T.E.;调查，M.L.、K.H.、M.N. 和 T.E.;方法论，M.L.和M.N.;资源，T.E.和M.N.;软件，M.L.;验证：M.N.和T.E.，数据管理，T.E.，M.N.，K.H.和M.L.;写作——原始草稿准备，M.L.;写作——审校和编辑，M.N.、T.E.、K.H. 和 H.H.;可视化，M.L.;监督，H.H. 所有作者均已阅读并同意该手稿的出版版本。

Funding: This research received no external funding.
资金：这项研究没有获得外部资金。

Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable.
机构审查委员会声明：不适用。知情同意声明：不适用。

Data Availability Statement: Additional details of the ANFI and JNFI can be obtained from the websites of the Austrian Federal Research and Training Centre for Forests (http://bfw.ac.at/rz/wi. home, accessed on 6 June 2022) and the Japanese National Forest Inventory (https://www.rinya. maff.go.jp/j/keikaku/tayouseichousa/, accessed on 6 June 2022). The English Annual Report on Forests and Forestry in Japan can be found at https://www.maff.go.jp/e/data/publish/index.html, accessed on 6 June 2022.
数据可用性声明：有关ANFI和JNFI的更多详细信息，请访问奥地利联邦森林研究与培训中心（http://bfw.ac.at/rz/wi.home，2022年6月6日访问）和日本国家森林清单（https://www.rinya.maff.go.jp/j/keikaku/tayouseichousa/ 2022年6月6日访问）的网站。《日本森林和林业年度报告》将于2022年6月6日 https://www.maff.go.jp/e/data/publish/index.htmlaccessed 查阅。

Acknowledgments: I would like to express my deepest thanks to Shinji Yamamoto for teaching me a lot about Japanese forestry and for taking me to Kamaishi to meet the Kamamorikumi Association of Private Forest Owners. I would also like to express my gratitude to Eduard Hochbichler and the people at the Institute of Silviculture, who gave me the possibility of traveling to Iwate University back in 2019. Finally, I would like to thank Christoph Pucher for their valuable feedback.
致谢：我要向山本真司致以最深切的感谢，感谢他教了我很多关于日本林业的知识，并带我去釜石会见了镰森龟岛私人森林所有者协会。我还要感谢爱德华·霍赫比希勒（Eduard Hochbichler）和造林研究所的人们，他们让我有机会在2019年前往岩手大学。最后，我要感谢 Christoph Pucher 的宝贵反馈。

Conflicts of Interest: The authors declare no conflict of interest.
利益冲突：作者声明没有利益冲突。

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