Ecological studies in the tongnai river basin. R. G. Mills, A. B., M. D

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R. G. MILLS, A. B., M. D.

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The peninsula of Korea is essentially mountainous with the principal range running nearer the eastern coast from a whorl of mountains in the north clustered about “Paik Tu San,” the “Ever-white Mountain,” clear to the extreme south, the peaks becoming lower and lower as you go southward. A smaller range branches from this main one and runs westward toward Manchuria just north of the 40th parallel. Another small range springs from the main axis a little farther north and runs northwest forming with it an angle of perhaps 30°. The Tong-Nai River is one of the water courses which drain part of the western slope of the principal range and the adjacent sides of the subsidiary ranges, two branches uniting about 60 miles above Kang-Kai (Japanese pronounciation, Ko-Kei) into a stream perhaps 100 yards wide. By the time it has reached Kang-Kai it is nearly 175 yards wide and at its mouth another 60 miles farther down it has attained a width of fully 250 yards. The general direction of its flow is north and west until it unites with the Yalu River or “Am-Nok-kang,, which has its source farther north.

The country drained by this river is entirely mountainous and is very old geologically. The hills are largely composed of granite and similar rocks in more or less advanced stages of decay, but a few outcrops of good limestone and marble occur. Volcanic action was apparently operative at some former time as “Paik Tu San” is an extinct volcano with a lake in its crater. However, at the present time not even traces in the form of hot springs remain. It might be noted, however, that a piece of tufa was discovered floating down the Yalu River about four years ago by Mr. H. E. Blair. A

*Article No. 7. Research Department, Severance Union Medical College, Seoul, Korea. (Chosen)
[page 4] dense forest of pine covered the hills clear to the top until the hand of man carrying torch and axe produced a very material change everywhere except in the most remote parts. The larger trees have all been removed and near the towns and villages even the underbrush is gathered for fuel. The patches of ground are cleared by fire in view of the spring planting and this left to itself, spreads to the hills where it

does great damage.

The climate of this northern country is comparable to that of lower Canada. The winters are cold and bracing and the river is frozen over for a period of three and a half months. The summers are not hot but sufficiently warm to ensure good crops. The prevailing southwest summer wind brings the moisture from the warm ocean current that strikes Japan from the south and precipitates it over almost the whole of Korea, producing a distinct rainy season during the month of July and portions of June and August. The hills being largely denuded of forest, these heavy rains make quick impressions on the riven One rain in July, 1909, caused a rise in the Tong-Nai River at Kang-Kai of twenty feet in five hours.

The Tong-Nai River has been explored from one end to the other during the course of this study which covers the seasons of 1909 11 inclusive, the source of one branch at the Tai-Kai Pass being visited once, another source at the Kai- Au-Kai Pass three times and three trips were made down the river as far as Antung, Manchuria, at the mouth of the Yalu River. It seems to be the same as any river in a mountainous country being restrained quite frequently in its course by barriers of solid rock. There are no falls but the rapids are very numerous and the current is everywhere swift. Between these rapids the river often spreads out a little and the current becomes somewhat slowed, but nowhere does it become slow enough to change from a bed-eroding stream to one whose banks are chiefly affected. Hence it is not surprising to find no wide flood planes or ox-bow lakes and the bed of the stream is always broadly V-shaped. Such conditions do not allow changes of topography to occur very [page 5] rapidly yet the effect of the forces that are operative can always be seen.

The bed of the river is of three kinds only,—the solid rock bottom with considerable variation in the velocity of the current; the rapids filled with boulders ; and the intermediate reaches of rocks, gravel and angular sand. Mud is a factor that needs no consideration. Here and there small tributary streams have created an almost endless variety of local conditions along the banks, but the bed of the river is practically unaffected.

This study has been limited to the main stream with some attention to two large tributaries, the Poong-Moun River and the Ma-Ma-Hai River, which unite with the Tong-Nai, one on either side of the city of Kang-Kai. The influence of small streams joining the larger one has been carefully eliminated as it tends to confuse rather than elucidate the problem. Likewise the “torrent portion” of the river’s origin has not been studied for the same reason. This leaves a stretch of river 175 miles long for our consideration.

In many places it is possible to distinguish an advancing and an eroding bank and occasionally the difference is quite marked. Physiographically the zone at the water’s edge and for a few feet back, is the same on both sides except where very active erosion of an easily affected bank is taking place. Another exception to this statement is noted both above and below any large rocky obstruction on one side of the river. Here the erosion of the bank has been at a minimum and vegetation has grown clear down to the water’s edge. Typically this water’s edge zone designated “A” in the classification scheme, is made up of sand gravel interspersed with boulders of various sizes. It is subject to frequent changes of water level and to the action of ice in the spring. It is truly a “zone of stress.”

The intermediate zone which comes next above is the ‘‘zone of annual inundation.” At least once a year during the rain y season this portion is submerged for from two weeks to a month and may be washed clean or covered with a layer of sand. On the advancing shore this bank is quite [page 6] sloping, rough and stony, the monotony being broken here and there by bushes and drift wood. Deltas created by tributaries during high water often modify this topography and high water cut-off channels are not infrequent. “B” is used to designate such a bank composed of rocks with a small varying amount of sand, and “C” means a stretch of almost pure sand well back from the water’s edge. These sandy places are occasionally found and are usually due to some local condition regularly modifying the strength of the current during high water. A large one occurs below the mouth of the Ma-Ma-Hai River and a still larger one bears the same relation to the Poong-Moun River. On the eroding shore the bank is much steeper, and bare rock or earth and evid-ences of undermined and fallen bank are common. Trees and bushes with uncovered roots loaded down with drift wood are often seen. “G” means a bank in this middle zone composed of rock only.

The upper zone is one subject to a great deal of variation. It is rarely under water and then only for a very short time. It is the connecting link between the river and the bases of the hills and wherever circamstances permit, is used for agricultural purposes. The hand of man has modified it by ditches, rice paddies and cultivated fields of corn and beans, but there remain many places still untouched. These are usually next to the river where for fear of losing a crop from especially high water the land is allowed to lie uncultivated Such land is covered with a fairly good growth of grass and is spoken of as

The zone about the high water mark on a rocky bank is called “H,” and is practically the same as the middle zone “G “ and continuous with it

Any system of classification so artificial in nature as to be based upon the variation of any one factor no matter how im-portant it may appear, is almost certain to be found unsatis-factory in many ways. In this study no such simple classification suggested itself, on the other hand the multiplicity of influencing factors is everywhere evident. Meteorological conditions were practically constant for all the zone and the [page 7] plants found there, totaling 396 species and varieties are all ‘‘facultative hydrophytes,” being able to withstand immersion for a time. If the water content of the soil were the criterion then the flora of the water’s edge would be constant whether the bank were rock, gravel, or sand. In this case the amount of sand available for the roots to take hold of was apparently the determining factor, but this in turn was dependent upon the variations in the current and factors which influenced it.

The moisture and the character of the soil were identical in “C” and in the “willow islands” formed upon it, but the character of the vegetation was markedly different. The former is added to slightly each year.

“B” is productive or not in proportion to the extent of the action of the forces which would cause a deposition of small amounts of sand between the boulders. When willows gain a hold upon such soil they change the character of the secondary flora back toward that found on sandy beaches but still retaining some distinct differences. In a few places the character of “B” has been modified in another direction. In addition to the deposits of sand there has been incorporated a little earth. Such a soil becomes firm and supports a still different flora, and it for convenience is designated

After all, the study of ecology refers back to the individual plant or species as to whether the conditions found in any particular locality are favorable or not for growth and development. In a mountainous country it can be taken for granted that the seeds of practically every species at some time or other have been washed down by the rains and floods and spread broadcast over the river bottoms. Perhaps a con- siderable proportion of these seeds did not find conditions suitable for any development but simply decayed and were gene. Still another portion germinated and developed until the floods came and they too disappeared- The number of these seedlings seen in the spring which could not with any degree of certainty be identified was quite large. Still others were able to attain full development in certain of the various conditions which are found in the river bottoms and a more or less detailed study of these stragglers gives us new light [page 8] on their adaptability to environment different from that gained from observing them under more favorable circumstances. The presence or absence of any plant within the range of the river’s influence is an indication then of the successfulness of its means of dissemination and of its ability to live under the conditions found. The relative abundance of any species is an index of the importance of one or both of these factors. This applies primarily to seedlings, whereas the development of a plant to the point of fruit-bearing is a matter that concerns its ability to adapt itself to the new environment, especially to that of immersion for a time. Some of these annuals reached maturity before the rainy season began, while others made very little growth until after it was past. The perennials which were able to live and multiply under these severe conditions were the best means of comparison of the different zones of life.

From the standpoint of the essentials which each plant demands for its continued existence this study is incomplete and is merely a contribution toward a knowledge of the life history of each, from the standpoint of dissemination by water and growth under certain definite meteorological conditions.

During the spring and summer of 1911, observations were taken of the condition of the weather and the monthly averages are given in the accompanying table. Through the kindness of Dr. Y. Wada, Chief of the Weather Bureau of the Government General in Chosen, the following instruments were secured:一

1. Thermograph

2. Centigrade Thermometer

3. Lambrecht’s Polymeter and Hygrometer

4. Pluviometer registering in m. m.

5. Evaporimeter registering in m. m.

Observations were made three times daily with these in-struments and in addition note was made of the direction and velocity of the wind, variety and extent of the clouds and any special condition that arose.

Wind was a factor of very little importance, there being no very strong wind, merely an afternoon breeze and some-[page 9]times a slight one in the evening. The “Land of the Morning Cairn” well deserves its name.

Clouds were estimated quantitatively on a basis of 10, meaning thereby a sky completely covered. The daily average of the three readings was made out to one decimal place and then the monthly mean calculated. The result followed very closely the amount of precipitation for the corresponding months.

Perhaps the most noticeable of the general meteorolgical conditions was the rarity of electrical phenomena. Thunder and lightning do occur, but during three years there was no discharge which made one think something must have been struck and indeed no reports of injury to man, beast or tree have been received. On very rare occasions there have come in reports of damage done by lightning in other parts of Korea, especially in the littoral zone, but even there this phenomenqn is unusual

The month of April was cold and raw, during the first half the thermometer registering below zero Centigrade on a number of occasions. The snow that had covered the ground all winter was practically gone when the month opened The earth was still frozen to a considerable depth. Snow fell in slight amounts on two occasions. Rain was recorded on half the days of the month and dew was practically ab- sent. The temperature generally remained low with an average daily range of 11.79° C. In protected places the early flowers got a little start so that by the last of the month several were in bloom.

May opened with the weather pleasant and fairly well settled. The nights were still quite cool but the midday average was relatively high, giving a daily range of 15.81° C. Rain fell on one third of the days but the actual amount was not large. Rapid evaporation and low humidity graphically show that May was a dry month in comparison with those that followed. Vegetation was now advancing rapidly and most of the spring flowers were in bloom.

The same kind of weather that characterized May was also found during the first week or two of June. The nights [page 10] as well as the days by this time had become much warmer and the daily range was about the daily range was about the same, i. e. 11.11° C. Rain fell on four fifths of the days and the actual amount of the precipitation was greatly increased, evaporation considerably decreased and the humidity correspondingly increased in spite of the higher temperature. Showers and sunshine frequently alternated and vegetation quickly became rank. The excess of precipitation over the evaporation made veritable hot-beds out of the sand stretches and those previously barren areas were soon thickly carpeted with vegetation.

July was the middle of the rainy season and during this month came most of the high water. The heavy rains lasting from hours to days falling on an already superaturated earth, caused very rapid rises in the rivers and the banks were soon overflowed. The geographical distribution of these heavy rains usually more or less localized, caused considerable variation in the relative overflow of the different tributaries and influenced the character of the damage done by the current Here and there the bank was torn out bodily and where ever there was any obstruction to the current there sand was deposited. The amount of this deposition was never very great, often just a thin layer among the plants that still maintained their hold. Rain fell on four fifths of the days and the amount exceeded that of June. Evaporation was a little less and the humidity much higher in spite of higher night temperatures. At times this humidity was quite oppressive although less so than in most other parts of Korea. There were heavy dews every night and everything dripped with moisture. The rank growing plants were now in abundance and the smaller vernal forms were completely lost sight of.

The rainy season lasted until nearly the middle of August Records were personally kept during the first two weeks and then the instruments were turned over to another. In some way the record was not quite completed although that which is lacking is not essential. By the middle of August the growth of most plants is complete so that those able to come to flower would be able to reach maturity. [page 11]

With the first of September the nights began to turn colder and the colors in the maples appeared The entire month was quite dry and several frosts occurred before its close. Snow then was frequently seen in the mountains and ice began to form along the river bank.

Temperature. April May June July August Sept.

Aver. 5.30 A. M. 2.77 7.20 14.06 19.07 15.26 14.4

„ 1.30 P. M. 12.48 21.24 24.22 24.3 28.17 24.52

,, 9.30 P. M. 3.19 13.77 17.09 21.13 21.73 16.93

„ Maximum 13.76 22.36 24.71 28.74 29.99*

,, Minimum 1.47 6.47 13.61 18.84 18.66*

,, Daily range 11.79 15.81 11.11 9.55 11.35*


Aver. 5.30 A. M. 70.53 86.10 91.5 93.87 60.2 83.96

„ 1.30 P. M. 46.93 3333 51.97 57.26 47.69 56.26

,, 9.30 P. M. 93.47 61.00 85.97 93.68 52.10 85.57

Clouds, (basis o f 10)

Aver, daily 6.72 5.01 6.39 7.37 7.05 5.10

Precipitation, (in mm.)

Total for month. 72.70 66.60 159.45 251.85 87.64 76.80

Aver, daily 2.345 2.15 5.315 8.12 2.82 2.53

No. of rainy days 16 10 24 24 13 10

No. rainless days 14 21 6 7 18 20


Total in mm. 83.2 178.9 137.85 127.2 122.67 102.6

Aver. daily 2.776 5.77 4.595 4.1 3.96 3.42

* First 17 days only.
The river bank opposite the city of Kang-kai which stretches across the mouth of a short wide valley, shows three distinct terraces formed during the past history of the river. The upper probably represents the bed of the stream when it made a long detour around an isolated hill that now rises from the midst of the old original flood plane- Then the river made a short cut in the line of its present channel but about 40 feet abcrve its usual water level, forming a middle terrace. [page 12] The lower terrace is shown as the top of the bank in figure I and is about 20 feet above low water mark. The exposed face and top of this lower terrace only is available for study as all above is in rice fields. The stones composing the bank are greatly water worn and are of all sizes from that of the fist to that of a man’s head. On the top is a layer of sand and earth that supports a vigorous vegetation and during the process of lateral erosion of this bank it has been somewhat undermined, but, still bound together by roots, it has applied itself to the face of the slope. The upper end of this mile of river bank is somewhat exposed to active erosion, but about the middle of its extent the current deviates to the opposite side and allows changes to take place in its character. These terraces are more nearly level than the present river bed so that in the lower half of its extent there is a narrow but gradually widening strip of bank that is above high-water mark. The result is that whereas the upper end is unfavorable for plant growth and is consequently relatively unproductive, a combination of conditions affects the middle and lower parts encouraging a more luxuriant vegetation:一-

Figure I. was taken near the upper end of this eroding stony bank and shows the first steps of the reclaiming of a bank when for some reason it is protected from active erosion by the current, although vertical erosion due to its steepness is still quite active. It is evident from the illustration that invasion of this barren land is taking place from two directions ; the beach line flora is creeping upward in proportion as there is sand deposited between the rocks and the sodland flora from above, is gradually spreading downward where that which is undermined can find enough soil for growth. List I. includes all the plants found on this section below the evident edge of the sodland above and excluding the wet sand flora at the water’s edge. The list includes 93 varieties of which 9 are shrubs. One plant especially common in this locality is Artemisia vulgaris, shown as the tall weeds in the foreground of Fig. I. In addition the more common and characteristic plants were Rosa davurica, Silene repens, Crataegus pinna- tifida, Euphorbia pilosa and Artemisia scoparia.

Fig. I. The upper end of the mile stretch of river bank opposite Kang-Kai. The plant prominent in the foreground is Artemisia vulgaris. Note the strip of sod-land vegetation that is creeping down from above. [page 13]

In list ii. Have been tabulated the plants found in the sodland above this bank which is typical of that designated uen and when compared with list l there are varieties in the latter whose presence cannot be explained supposing virtual transplantion from above.

The relationhips of some of these 49 plants are quite varied; cratiegus pinnatifida and acer ginnala are found on any river bank in most any situation; peaceianum decnrsivum where other vegetation is low and where there is plenty of humus and moisture, hence the rarity here; sileno repens and clematis koreana are characteristic of open stretches of gravel “b”. Those found more on dry sandy stretches are lactuca denticidata, and equisetum arvense and those in wet sand near the water’s edge are nasturtium montanum and n. Palustre, polygonum perfoliatum, ranunculus chinenns, hosta lancifolia and carex heterolepis. Several more are those whose better development is found in more mesophytic conditions as cuscuta japonica, eaonymus al ita, rabus crategi- folios, vicia craccaf moehringia laterijlora and patrinia scabiosaefolia. Another group is fonni elsewhere in waste ground and represented here by geranium sibiricum, arabis perfoliata, geum strictum, carduus crispus and humidiis japonica. Of those that remain corydallis pallida is typical of rich humus banks anywhere that are eroding to such an extent that most other plants cannot maintain a foothold in the loose shifting earth- fagopyrum esculentum and glycyine hispida extensively cultivated in the mountains and loads of them are carried back and forth so that their presence could be explained in numerous ways. The two grasses poa pratensis and agropyram sernicostatum, van ciliare are both found in this nidified strip of sdd above and retain a place in the further develtpment of the bank in lists iii and iv the former occurred in thu series only, while the latter is more widely distributed, being found with this exception in almost every condition in the river bottoms- the absence of these two forms in

Several species were represented by immature specimens only; Artemisia Messerschmiitiana, A. silvatica, Chrysanthemum sibirijum. var. acutilobum, Lactaoa laciniata, Oenanthe stolonifera, Peucedanum terebinthaceum. Polygonum poly- morphum, var. undulatum and Siegesbeclcia orientalis.

Mention was made of the undermining of the edge of the the sod until it applied itself to the upper few feet of the sloping bank. Apparently the only change that has taken place is the transition from a horizontal plane to a north slope with a gradient of perhaps 30°. This much was sufficient, however, to make radical changes in the vegetation. It is still essentially a close sod, even the pieces undermined, completely separated and slid d )wn the bank a little ways retaining that character, yet the Zoysia pungens, the characteristic grass of “E” has been completely replaced by Hierochloe odorata, Agropymm semicostatum var. ciliare, Garex drymophylla, var. akanensis, C. breviculmis, Poa pratensis and P. trivialis. Seven new plants found in neither list I. or II. have appeared, all perennials and five of them shrubs; they are Securinega fluggeoides, Neillia Millsii, Ulmus japonica, U. pumila, Thalictrum aquilegifolium, Rhamnus parvifolia and Selaginella helvetica. All of these plants with the exception of the two species of Utmus are characteristic of masophytic hillsides and figure more prominently in lists III and IV which show the mesophytic development of the bank. Selaginella is the only one of these that seems to prefer a northern slope and plenty of shade. A.number of plants with mesophytic tendencies that are sparingly represented in lists I and II become much more common in this strip. Fig. II represents the bank as it appears in its middle section and shows the process still further advanced. The foreground among the rocks resembles Fig. I very closely, the plants Artemisia lavandulae- and A. vulgaris, being quite prominent. But from above the mesophytic vegetation has made considerable advance over the upper half of the bank. From this point on the river has sunk to such a level that the top of the bank is above high-water mark. Here the plants characteristic of the wooded ravine and hillside have invaded in considerable

Fig. II. View typical of the middle section of the bank described in the text, showing the development of a more vigorous growth in the upper part and less change in the lower. The plants prominent in the foreground are Artemisia Lavandulaefolia, and A. vulgaris.

[page 15] numbers. Most all the plants in list I are greatly increased in abundance and those which are especially characteristic are: ——

Campanula glomerata Clematis fusca

Clematis, recta var. Mandshurica Crataegus pinnatifida

Lespedeza bicolor, var. Sieboldii Maius baccata, var. Manshurica

Oxalis corniculata Peucedanum decursivum

Philadelphus schrenkii Prunus ssiori

Thalictrum aquilegiflium
Some of the plants which have taken advantge of the conditions favorable for mesophytic growth and hence appear in list iii and not in list i are the following:一

At and above high water mark—


Acanthopanax sessiliflorum.

Juglans manshurica

Malus baccata, var. Manshurica


Berberis amurensis

Corylus heterophylla

Lespedeza bicolor, var. Sieboldii

Philadelphus schrenkii

Rhododendron davuricum

Trypterygiura Regelii

Viburnum Sargentii

Woody climbers.

Amperopsis heterophylla

Celastras articalatis

Schisandra chinensis

Vitis amurensis


Angelica cartilagino-marginata

Campanula glomerata

Chelidonium majus

Hemerocallis middendorfii

Polygonum multiflorum


Thalictrum aquilegifolium

[page 16]

Herbaceous Climbers.

Calystegia sepium

Clematis fusca

Codonopsis lanceolata

Dioscorea acerifolia, var. manshurica

Menispermum davuncum

Smilax herbacea

Sedum Aizoon


Athynum nipponicum

“ spinulosum

Onoclea germanica

The 31 plants represented in this list are practically all distinct wooded ravine and hillside forms and together with Securinega fluggeoides found also in list I, represent the overlapping of the more pronounced mesophytic flora, The remaining plants in the list that follows occur well below high water mark and the presence of practically all can be explained on a basis of change in character and stability of the soil rather than by extension from adjacent areas. A brief description of these may throw a little light upon their ecological relationships.

Iris sibirica, common on open grave sites and half sodded land.

Panuncus pensylvanicus, var. chinensis, usually in damp places along streams.

Lysimachia barystachys, common on upland hillsides, but abundant in open grass land above high water mark.

Gentiana yokusae, var. japonica, being no more than ½inch high it is only found where surrounding plants are not very tall. Abundant among the short grass of “E” it is quite hardy and resists drought well.

Selaginella helvetica, only found where rich earth, stable soil, dampness and shade are combined.

Orobanche caerulescens, although Artemisia scoparia on whose roots it is parasitic is very wide-spread in its distribu- tion it is confined to loose sand or an eroding sandy loam [page 17]bank. It penetrates from three to six inches deep to tap the root and here is found only in the softer not thickly vegetated places.

Fraxinus rhynchophylla, as yet found nowhere but in this sort of a situation.

Pyrus ussuricnsis, characteristic of just such localities, though following small streams up in the same way, where it reaches its maximum development,

Potentilla centigrana, var. manshurica, spreads over gravelly banks not far from the water’s edge.

Aquilegia vulgaris, Most abundant beside very small spring streams in very rich wet earth. Occasionally as here in earth just as rich but not constantly wet, although prevented from complete drying by other vegetation.

Cerastium serpyllifoliurn, very slender annual in damp places. Noted also common in upland rice fields. Matures before the rainy season.

Senecio campestris, very abundant on open gravelly sites but rare where rank weeds compete. Plant very hairy and more adapted for resisting drying than growing in fairly moist mesophytic surroundings.

Phragrnitis pumila, usually prefers rocky ground with wet subsoil where the long runners can spread widely. Noted also in damp ravines and along small streams. Hypericum Ascyron, a typical river bottom plant. Stachys aspera, a common weed in open moist waste land.

Agrostis scabra, widely but not abundantly or character-istically distributed.

Potentilla Kleiniana, found in virtually the same places in which species of Ranunculus would be expected.

Spirea salicifolia, in rich sandy moist places. [page 18]

Sorbaria sorbifolia, var. stelhpila in our studies matured sparingly in only this situation.

Hemerocallis minor, found commonly in open pasture land and hence rarely here.

Calainagrostis arundinaceay observed in moist or wet places and where a mesophytic development is taking place.

Spiraea chamaedrifolia, observed here only and to a very limited extent.

Tilia amurensis, rare here, a hillside form.

Veronica spurea, a few here and in the next higher stage of mesophytic development

Syrinqa amurensis, observed only in this situation and some on “H.”

Rhamnus globosa, a mesophytic shrub found commonly along the banks of streams.

Carex Maackii, found nowhere else as yet.

Achillea sibirica, occurs sparingly in mesophytic societies, especially where other plants are not very high.

Plectranthus inflexus, fairly common here and in the crevices of rocks in situations “G” and “H.”

Euonymus Maackii, one of the characteristic plants of list IV and occurs in direct proportion to the richness of the soil.

Several plants were found only in lists III and IV, they are Carex siderosticta, Silene firma, and Spodiopogon sibiricus.

Young immature specimens of Leonurus macranthus and Sanguisorba officinalis were found.

The following were observed only in this situation, Aster scaber, Carex drymophila, Galium boreale, var. latijolium, Lactuca lanceolata, Salix vagans, var. cinerascens, Saussurea koraiensis and Sonchus arvensis.

Although quite a list of plants has been added to the flora of the bank incident to its transition toward a more mesophytic condition, there are a few that have dropped out in list III and do not reappear in list IV.

Carex heterolepis wet sand group

Moehringia lateriflora ,, ,, ,,

Lactuca versicolor weed waste ground

Erigeron canadensis ,, ,, . ,,

Polygonum aviculare, var. laxum ,, ,, ,,

of the remaining 13, five were limited sharply to list i, and three more are so short as to be easily overgrown by the heavy vegetation. the last five are very heterogeneous and

Fig. III. Bank completely covered with vegetation. Picture was taken half way up the bank. [page 19]

do not lend themselves to classification. There is apparently nothing surprising about the disappearance of these plants except to further indicate that the change is away from those conditions favorable for their growth and development.

The lower end of the bank has been completely covered with a thick growth of vegetation until the character of the underlying soil is nowhere visible. Fig. III shows the general appearance of this growth very well. It is quite evident from a study of this development that under the meteorological conditions to be found here, a rich mesophytic growth of plants can overcome the vertical erosion of even a bank as steep as this one which is still subject to high water inundation when the effect of the horizontal erosion of the current is removed. As would be expected the difference between lists III and IV would not be great so far as the strictly mesophytic plants are concerned. In reality the visible difference is rather one of quantity than quality, most of the plants being simply increased in number.

The list of plants found for the first time in this location were:—

Polemonium coeruleum, as yet found only in this locality. Aruncus silvester, a moist hillside form. Osmunda cinnamomea, moist hillsides. Impatiens nole-tangere, grows abundantly in the bottom land on good ground becoming especially rank during the rainy season.

Commelina communis, a very troublesome weed that during the rainy, season apparently fills in with a vigorous growth every otherwise unoccupied space. When pulled up by the roots and left lying on the ground it invariably takes root again from every joint.

Cnidium Monnieri, probably several species are included in this report as immature forms were hard to differentiate. Hosta caerulea, common in shady damp ravines. Lilium elegans, rich hillsides.

Veratrum Maacki, open rich hillsides where not shaded by trees.

Lycopus hicidus, same situations. [page 20]

Ulmus japonica, hillsides.

Sanguisorba officinalis, noted in crevices of rocks filled with humus, in “g” and also on the island among the willows.

Filipendula rufinervis, seen along a stream in a high mountain ravine and on the mesophytic sand flat or “C meso.”

Aster incisus, occurs at about the same distance from the water’s edge in the mesophytic nooks among the rocks and on the “mesophytic bank” as per list xii

Astilbe chinensis, open hillsides.

Circaea alpina var. Caulescens, in damp shady places Especially under projecting ledges of rock.

Viola chinensis, var. Subsagittata, where there is good soil, no sod and among plants that do not grow very tall at Least by blooming time.

Convallaria majalis, open hillsides without much shade, grows taller and the plants farther apart the steeper and looser the soil.

Galium asprellum, var. Dahuricum, on rich hillsides, grows up as high as the surrounding vegetation when this is not over five feet high.

Lysimachia vvlgaris, var. Davurica, among weeds along streams.

Silene aprica, along streams where earth is dry and hard and other plants not too pressing.

Geranium maximowiczii, rich hillsides where other plants are not very high and where there is plenty of moisture.

Rvbia cordifolia, rich hillsides.

The presence of a plant in this society which does not occur in any other of our studies is indicative of the inability of that form to withstand the local conditions, presumably the temporary immersion There are a few of these mentioned, Aegopodium alpestre, Angelica anomala, Asarum Sieboldii Aster Maackii, Melampyrum laxum, Microlepia Wilfordii, Pediculalaris resupinata, P. oppositifolia and P. spicata, acavleatum, Rhamnus Parvifolia, Saliz multinervis, and Poly8tichium Torilis japonica. Others in the preceeding belong here also. [page 21]

It is noticeable how many of those absent in lists I,II and III and present here for the first time occur once or twice in the other lists yet to be described. Naturally these situations are the ones nearest allied to the mesophytic type of life, to wit, the “meso nook” (list IX) “C meso” (list XVI) and a few on the rocky banks “G” and “H” (lists X-XI). This stage in the development of a mesophytic flora sees the end of practically all the forms that were at all characteristic of the rocky river bank, giving place to those more distinctive of the mesophytic hillside and damp ravine :—

Comparing list IV with list III it appears that a number of plants that were found in this and previous lists have disappeared, some of these are.

Gentiana yokitsae, japonica, plant too small to receive any sunlight.

Orobanche caerulescens, found in more open situations. PotentiUa centigrana , var. manshurica, on open grave sites.

Aquilegia vulgaris, other vegetation too tall.

Carduus crispus, found in open situations where it can rise well above surrounding vegetation.

Onoclea germanica, generally in wetter, more open places, often along irrigation ditches.

Senecio campestris, prefers open grass land.

Fagopyrum esculentum, other plants too tall.

Juglans mandshurica, observed in Manchuria as a typical upland mesophytic forest tree, but here all cut out for its valuable wood. Small trees are occasionally found along the river banks in just this sort of situations.

Phragrnitis pumila, vegetation too rank.

Humulns japonica, usually in less stable plant societies.

Lactuca denticidata and L. lanceolata, more common on walls and exposed surfaces where erosion is a prominent factor.

Zoysia pungens, disappears where the tall plants create much shade.

Anemone Koreana, prefers more open formations. [page 22]

Artemisia lavandulaefolia and A. silvatica, are more abundant where plant equilibrium is not so well maintained.

Schisandra chinensis and Celastrus flagellaris, are hill-side forms.

Rubus crataegi-folias, is a road side and field margin type.

Salix gracilistyla, is never found so far up the hill sides.

Viola chinensis, and Hemerocallis minor, would be crowded out on account os their small size.

Chenopodium glaucum, is a road side and field weed.

The remaining ones of more or less importance are mentioned without comment, Corydalis pallida, Geranium si- biricum, Lespedeza juncea, Panicum sanguinale, Peucedanum decursivum, Salix vagarts, var. cinerascens, Silene firma and S. repens, Ranuculus pennsylvanicus, var. chinensis, and Thesium chinense.

In the area covered by list IV is to be found the nearest approach to a typical mesophytic plant society seen anywhere along the river course. That it differs in many particulars from that found at the base of the hills well above high water mark is to be expected, but the exact detailed comparison of the two is of necessity reserved for later study. We may, however, consider that this development is about as high as is possible under the conditions imposed by the annual inundation. The characteristic plants of this society are:—

Cuscuta japonica Lysimachia vulgaris

Clematis recta, van mandshurica Thalictrum aquilegifolium

Vitis amurensis Selaginella helvetica

Neillia Millsii Rhamnus parvifolia

Tripterygium Regelii Corylus heterophylla

Acer ginnala Euonymus Maackii

Viburnum Sargentii Lespedeza bicolor, var. Sieboldii

Polemonium coeruleum Aruncus silvester

Calystegia sepium Spirea salicifolia ;

Polygonum multiflorum Metaplexus japonica

Campanula glomerata Rhamnus globosa

Filipendula rufinervis Aster incisus

Astilbe chinensis

To attempt to shorten this list would involve one in great difficulties; to say of two equally common plants that one is more characteristic than another would be arbitrary at best.

Fig. IV, This is another view of the bank of which fig. III. represents the upper part and shows in the center of the foreground such a shore line which has become decidedly sandy. In addition another step in the process of development of the bank has taken place. In the background a little farther up stream there has developed on the sandy bank a further obstruction to the current to be described later as the “willow island formation.” This newly-formed tongue of land has projected out into the current and is somewhat curved down stream until there has developed quite a little protected corner. The flora that has developed in this corner is described in list VII. [page 23]

Nor is it possible to say that these plants are characteristic of this society alone for with the exception of Polemonium coeruleum and Aruncus silvester, found only in list IV and Campanala glomerata in III and IV,these are all found in considerable abundance on the mesophytic hillsides. Several of these however, are fairly closely limited to the river bottoms and are not found to any great extent elsewhere. They are Neillia Millsii, Rhamnus parvifolia, Tripterygium Regelii, Acer ginnala, and Euonymus Maackii.

To this list of shrubs and trees. should perhaps be added the names of a few others that reach their maximum development in other situations but to which this limitation applies equally well- I refer to —

Crataagus pinnatifida list I and III

Prunus ssiori list III

Philadelphus Schrenkii list III

Malus baccata, var. manshurica list III

Salix gracilistyla “willow island formation”

Maackia amurensis list X

Pyrus ussuriensis beside tributaries
The same factor, i. e. the deflection of the current which allowed the changes depicted in fig. 1—III to take place in the upper part of the river bank has also produced changes in the lower. Fig. I shows to a slight extent that instead of exhibiting a rugged waterworn beach of boulders as would be expected from the character of the bank, there has been a deposition of sand. As the presence or absence of sand is the chief determining factor in the amount of vegetation in any given beach line we find the absolute barren condition at the tip of any advancing bank at one extreme, and that in the foreground in fig. IV at the other. The average shore line as described in the introduction and designated “A” occupies a middle position, in that here and there are little deposits of sand in the crevices between the boulders sufficient to support a scant vegetation. This is a transient flora being completely destroyed each year by the movements of water and [page 24] ice but renewed annually from seeds washed in and deposited with the sand The enumeration of these plants then in list V is an indication not of their ecological value in this connection but rather of their abundance farther up stream and a measure of their adaptation to dissemination by water. The same may be said with equal propriety about this same set of plants in whatever zone they may be found.

It is hard to single out any one species as being charact-eristic, for quite a number are occasionally found and none in any great abundance. This list would be a great deal longer if it were possible to identify more of the seedlings before the flowering time comes. Of those that were recognized a large percentage are annuals and most, if not all of those that are ordinarily perennials showed only the first year’s growth. In spite of these difficulties it is evident that a considerable number of these plants perpetuate themselves in this situation by reason of the fact that they mature before the floods come. If any plants could be called characteristic of this situation they would doubtless be these,—

Carex heterolepis

Ranunculus pennsylvanicusf var chinensis

Viola biflora

Moehringia lateriflora, generally found on damp meso-phytic hillsides

Trigonotis peduncidaris, appears very early in the spring, matures and is lost sight of before most plants are well started.

Draba nemorosa, another very early form appearing on any bare spot exposed to the warm spring sun.

Capsella Bursa-pastormatures quite early•

And rosace Miformis, found typically at the edge of rice fields, where there is a saturated soil. Matures before the time of spring plowing.

The conditions found on the sandy shore line of the river are in a great many respects much more favorable for plant growth and development than those associated with the or- [page 25] dinary condition described as i{A.}9 The very presence of sand in any amount means that the bank is at least temperari- ly advancing and that such plants as are found there would suffer from the deposition of sand rather than from erosion about their roots. The rate of this deposition, however, is believed to be so small that the absence of any plants in list VI that belong in list V is apparent rather than real. On the other hand quite a number of plants occur on the sandy beach that were practically or entirely absent on the ordinary shore line. Some of those which occur in list VI and not in list V are as follows :—

Viola canina, while not very common here, yet this represents the hydrophytic limit in the range of this plant’s growth. The maximum development is reached on the mesophytic banks of smaller streams and again there is a decrease farther up the dryer hillsides.

Oxalis corniculata, also found commonly in mesophytic societies, seems to depend more upon moisture than the amount of sunshine or shade.

Brunella vulgaris, occurs chiefly in rather damp or wet places usually in fairly rich earth.

Orobanche caerulescens and Artemisia scoparia.

Acoyms Calamus, ordinarily found in ponds and wet places where drainage is poor.

Juncus effususy a pond or sand-flat form. The root system is extensive and is not influenced by sand deposition.

Beckmannia eruciforrnis, similar to the last in distribution, is a good sand binder and matures just about flood time, hence is widely disseminated by water.

Xanthium Stru:nariumf springs up on the sand-flats everywhere, very common also on

Saussurea uffinis, generally an upland plant and associated with other weeds.

Sciryus tahernaemontaniy same as Juncus effusus.

Other species areᅳ Carex heterolepis, Cerastium vulga turn, Geranium sibiricum. Geum stritum, Humulus japonica, Mentha arvensis, Onoclea germanica, Veronica Anagollis and Vicia Cracca. [page 26]

The plants meet characteristic of this situation are, —

Nasturtium montanum, abundant here but reaches its highest development under like conditions of moisture but where there is a little earth mixed with the sand, in “D”,

Ranunculus pennsylvanicus var. chinensis, here a perennial

Viola biflora, grows luxuriantly beside spring brooks and as small yearling plants here.

Equisetum arvense, vegetative forms quite abundant

Rumex crispics, although immature plants are often seen in “A” before the floods they have not been noted afterward. Plants here usually come to maturity in spite of the high water.

Cerastium serpyllifolium, matures here before the high water.

Mazus japonicus, occurs here frequently lying close to the ground, more common in damp places where there is rich earth.

Alopecurus fulvus, grows commonly at the edge of the water and matures at flood time.
The plants along the shore line are practically a repetition of those enumerated under the sandy beach flora so that special interest centers in those plants that are found out in the water. They form the transition to the drained pond flora. Since this is a special study of a single place all the plants found there could be said to be characteristic of it.

The following were very abundant and composed the majority of the plants there. ^

Juncus effusus.

” ” var compactus. k

Alisma Plantago.

Rumex crispus, not quite as common as on the sandy beach at or above the ordinary water line.

Scirpus tcibernaemontani.

Beckmannia eruciforrnis.

Alopecurus fulvus, not very common-

Fig. V. A general view looking up the river. On the right is an advancing bank with its islands of willow and clumps of Maackia. The left bank should be an eroding shore and would be but for the presence of the mass of rock from which the picture was taken. Instead it is a protected sand beach completely covered with vegetation and growing vertically from high-water sand deposition and apparently suffering little from the lateral erosion of the current. On the contrary the small mass of willows that have caught root out in the stream would suggest a positive aggression. This “willow flat” is shown at closer range in fig. VI.

Fig. VI. A nearer view of the “Willow Flat” shown in fig. V. It has become completely covered with vegetation during the long protection from erosion. Note the sharp demarcation of this society from that of the river bank above. [page 27]

These were all found in water varying from 2 inches to a foot in depth and seemed to little influenced by any ordinary deposit of sand. With extensive root systems they seemed to be very firmly anchored to the bottom.
When a bank is for a long period of time protected from erosion by a conveniently placed mass of rock there results a stage of development that is more advanced than that shown in fig. IV, such a condition is indicated by fig. VI. The topography and vegetation indicate that the shore line once followed its present form in the upper part of the picture, that it continued in this same line across the figure almost to the extreme left edge, then described a curve back again as shown by the edge of the taller vegetation in the foreground. All the land between this ancient shore line and its present one has been filled in by a gradual deposition of sand aided by the vegetation which has developed there.

It is difficult to speak of the genetis development of this area but it is evident that the willow Salix gracHiglans has had a great deal to do with it. There is nothing to indicate that this was even a sand-flat on which such plants as those found in list VII were prominent, in fact the edge nearest the water would lead one to think that the willows had done it all. The entire area is practically uniform being raised in small mounds and presenting a sort of mammillated apppearance. These little sand piles fairly bristle with the short simple willow shoots that seldom reach the height of 2 feet. The hollows between the mounds dip down in places to water level and in others are very little above it, they too being fairly well covered with willow branches. All the available sand among the willows is thickly set with Hosta lancifolia and these plants are especially abundant in the little depressions between the mounds. Other plants found there are Agropyrum semicostatum var. ciliare, and Lythrum salicaria van tomentosa ; the foxroer being widely distributed over the bottom lands and is never abundant in nor especially characteristic of any situation, while the[page 28] latter often grows in fixed sandy or gravelly soil very close to water level.

In addition were the following, Trifolium Lupinaster, Oxalis corniculata, Vicia Cracca, Viola biflora, Equisetum arvense, Spirea salicifolia and Inula britanica, var. japonica. The floods had cleared this area of those seedlings found as-sociated with the “Willow Islands” and named in list XIII, the ones enumerated being only those able to survive. None of these seem to be damaged by the prolonged immersion although Agropyrum is just coming into maturity at that time and Lythrum is in full bloom.

Along rocky bluffs otherwise exposed to a severe current are frequently to be found protected nooks that support an entirely different vegetation. In size these vary from a hand-full of sand to a stretch of a hundred yards in length. Their inclination is usually steep showing the effect of the repeated deposition of sand out as far as the current will allow, the steep edge thus formed being usually bound by the interlaced roots of a wide variety of plants. Such a formation can be regarded as quite stable, modified only by an occasional, at least annual immersion and the deposition of a thin layer of sand during the high water to compensate for that lost by vertical erosion the rest of the year. In the upper part of these nooks a considerable amount of humus collects making the soil quite fertile and this in many places reaches down quite close to the water’s edge. This rariation seems to be responsible for the differences in the relative abundance of certaint strictly mesophytic wet-sand plants when comparing one nook with another. The remains of such a bank is shown in fig. VII and its original character is seen in the point of land which apparently pushes out into the river. Two years ago this bank extended out to a line between this point and the lower left hand corner of the picture, but during an ex-ceedingly high flood in 1909 the Ma-Ma-Hai River cut a new channel across its own delta at a tangent to its former course. This was sufficient to turn the current partly against this

Fig. VII. A “Mesophytic Sandy Nook” opposite the mouth of the Ma-Ma-Hai River that is being actively eroded.
[page 29] fifteen foot bank with the evident result. A rise in the water a few days before the picture was taken carried away a mass of roots and debris that had accumulated from erosion during the preceeding winter and spring. The stratified structure of the bank is well shown in the figure.

The flora of an unmodified bank of this sort is resolvable into two zones only, being occupied by plants that follow in the natural course of evolution of the sand beach, while from above the plants characteristic of the hillsides come down remarkably close to the water. The plants found in this locality are catalogued in list IX. The characteristic plants of this society are,—

Neillia Millsii,quite common.

Ulmus japonica, although dropping out quite early in the mesophytic development of the bank yet appears quite commonly here, never reaching any size however.

Carex heterolepis, this is abundant in small pockets of catch sand near the usual level of the water. Its roots form a dense network and catch still more sand. The seeds mature at the time of high water, are torn off the plant and scattered broadcast over the river bottoms.

Iris sibirica, typical of moist places farther up the bank, it is able to approach nearer the water’s edge in this situation than in any other.

Cannabis sativa, commonly cultivated in the river bottoms but escaped and thrives in sandy soil such as this and “C.” When found in the soil occupied is a little more firm and other plants are rarely intermingled.

Hemerocallis Miadendorfii, a characteristic plant of “E” yet like Iris sibirica is found commonly here approaching quite close to the water’s edge.

Calystegia septum, commonly in or near cultivated fields in the bottom lands and from this as a center spreads into the sandy areas below high water mark.

Stachys aspera, although often a wasteland weed, yet it seems to demand plenty of either humus or moisture in the soil, there being an apparent reciprocal relation between the [page 30]  two factors. Here where both conditions are combined the growth is quite abundant.

Polygonatum verticillatum, a fairly permanent bed of loose sand well up to or above high water mark is the only situation in which this form has as yet been found.

Spirea salicifolia, seldom grows so far above the water level that its roots cannot penetrate to saturated soil.

Calamagrostis arundinacea, roots demand considerable moisture.

While not especially characteristic of this society a number of plants deserve at least some mention.

Lysimachia barystachys, although characteristic of “E.” like a number of others it comes down very close to the water’s edge.

Polygonum polymorphum, finds its highest development on the rich hillsides above high water mark where the brush wood has been largely replaced by rich mesophytic growth and where it can raise its flower stalk well above the surrounding plants, It constitutes a part of this society.

Ampelopsis heterophylla, ofter associated with the grape in the river bottoms but differs markedly in its distribution in that it comes down close to the water’s edge here and does not extend to any great extent up the hillsides.

Eupatorium Lindleyanum, in this study reported only from this situation.

Hosta caerulea, a considerably larger plant that H. lancifolia and like it requires considerable moisture. It is however found abundantly in the cool, moist, shady ravines of the river bluffs and does not grow below high water mark to any great extent.

Aster hispidus, reported only from this situation.

Arabis pendula, ,, ,, ,, ,, ,,

Saniculata elata, ,, ,, ,, ,, ,,

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