Monograph No. 36
NARA (HEIJO) IMPERIAL PALACE SITE CONSERVATION REPORT I
CONTENTS
Chapter I Physical Layout of the Heijo Palace Site
Chapter II Survey
1 Physical Survey
(1) Soil
(2) Water
(3) Vegetation
(a) Present Vegetation (b) Plant Remains
(c) Pollen Analysis (d) Root Systems
(4) Birds
2 Social Survey
(1) Existing Conditions
Chapter III Materials
1 Materials for Reconstruction
(1) Authentic Materials (2) Imitation Materials
2 Materials for Display
3 Materials for Landscaping
4 Materials for Maintenance and Other Materials
Chapter IV Techniques and Methods
1 Models
(1) Shelters (2) Relics
2 Reconstruction
(1) Full-scale Structures (2) Foundations (3) Wells
3 Display
(1) Pillars (2) Border Walls (3) Graves
(4) Roads (5) Capped Mud-walls
4 Removal
Chapter V Visitor Services and Maintenance Facilities
1 Electricity 2 Roads 3 Drains and Irrigation
4 Park Areas 5 Guide Boards 6 Display Rooms and Toilets
I Physical Layout of the Heijo Palace Site
An outline description of the Heijo Palace Site, an outline of the process of development of the planning and operation program for excavation and reconstruction in this decade, and also a description of the plans for the future Heijo Palace Site Museum are provided.
II-1 Physical Survey
1. Soil
The geological conditions and quality of the soil in this area were analyzed to obtain the data essential for reconstruction of the original structures in future projects.
The top soil of the site is generally alluvium. The top soil is thick in the southern area (about 3.5 meters); however, it is very thin in the northern area, exposing a diluvial formation just below the surface.
The soil is generally composed of clay, psamitic clay, sand mixed with clay, and gravel mixed with clay. The “N-value” in the standard penetration tests is generally less than 10, and some parts are found to be quite weak.
2. Water
The quality of ground water influences the preservation of underground remains. The result of the tests of present conditions provides useful information for planning the physical layout and maintenance of the site.
The following matters are examined: measurement of oxidation and reduction of underground water, the chemical process of “free CO2” exerting harmful influence on stone remains, locations of wells to observe the level and the quality of under ground water, and the methods and results of tests conducted annually from 1971 to 1977.
3. Vegetation
(a) Present Vegetation
Vegetation research has taken place continually in order to discover the most appropriate plants for use at the site in conjunction with planned physical layouts.
The study of weed distribution in 1970 made it clear that some groups of dominant species have advanced in a mosaic-like pattern according to the ground water conditions.
The study of weed habitat in 1973 revealed that in areas of uneven elevations perennial weeds grow on higher ground than annual weeds whether in a field or a rice field.
In research from 1974 to 1976 concerning the growth and distribution of “Andropogon virginicus L.”, it was found that the range of “Andropogon virginicus L.“ has steadily spread; left in a natural state the whole ground will most probably be covered with “Andropogon virginicus L.“ in less than five years.
It was observed that the variation of the percentage of germination causes after-ripening, which is one of causes of dormancy.
Comparing the research of 1977 with that in 1970, the stratification of “Polygonum Thunbergii Sieb.” has changed into the stratification of “Isachne globasa 0." and “Phragmites communis Trinius”, and the extent of “Miscanthus sinensis Anderss.” stratification has spread. The soil which covers the whole site has been gradually becoming more arid.
(b), (c), (d) Plant Remains, Pollen Analysis and Root Systems
The chemical characteristics of pollen and vegetation remains which are excavated in ditches, canals, and ponds has been analyzed continuously in order to study the original vegetation of the site. Effects of the root systems of present trees on archaeological remains has been researched in order to make a better plan the landscaping for future physical layouts at the site.
4. Birds
The observation of birds has been undertaken in order to study possible ecological changes due to the development of new physical layouts at the site.
The most dominant species were “Emberiza rustica” and “Alauda arvensis” which were the most frequently observed species during research in the winter of 1973.
In 1974, a total of 8 orders, 22 families and 37 species, of birds were observed. The numbers and annual variation of “Alauda arvensis”, which inhabits the area in all seasons, was also surveyed.
II-2 Social Survey
1. Existing Conditions
Studies have been undertaken to determine optimum conditions for the best use of the site.
According to a poll conducted in 1967, visitors who live nearby the site thought that the area should be developed as an urban park with many trees. On the contrary, those visitors from outside the area were more concerned that planning should allow for better viewing of the historical aspects of the site.
The poll taken in 1968 clearly showed that half of the visitors from nearby areas visited the site for walking or resting. The site serves well as part of their living environment.
A study conducted in 1972 determined that there were approximately 1,600 visitors per day. Half of the visitors entered the site from the east entrance. Visitors generally stayed for two hours in spring and autumn and for forty minutes in summer.
A survey of traffic in 1974 counted more than 10,000 automobiles throughout the site in a day; the number of bicycles was also considerable.
This study included some suggestions concerning the improvement of traffic conditions.
III Materials
The use of authentic materials for the reconstruction of physical layouts has become impossible in recent years due to the unavailability of sufficient quantities of such materials also of high quality. It has become necessary to utilize new materials, such as imitation materials and synthetic resins.
The following matters are considered: use of the available new materials, the process of production of new materials, the merits of using vegetable and mineral materials for display, the types and the use of boundary materials, methods of selecting plants for landscape architecture, and the design and maintenance of pavement, drains and fences.
IV Techniques and Methods
The following techniques and methods have been adopted in planning the physical layout of the site.
1 archaeological remains (shelters, full-scale models)
2 reconstruction (full-scale structures, foundations, wells)
3 display (pillars, border-walls, gravel, ponds, roads, capped mud walls)
4 removal (relocation of archaeological remains to new sites)
Techniques, methods, locations, plans, structures and finishes are summarized adding some remarks for each of the above items.
V Visitor Services and Maintenance Facilities
Maintenance and utility facilities such as roads, aqueducts, irrigation and electrical equipment are described, as well as facilities for visitors such as park areas, guide boards, toilets and display rooms. Information concerning the function, location, structures and program for each item is provided.
昭和54年3月31日 発行
平城宮整備調査報告I
奈良国立文化財研究所学報第三十六冊
