CONTENTS

Chapter I. The Foundation of Ecology
THE NEED OF A SYSTEM
PAGE
1. The scope of ecology [1]
2. Ecology and physiology [1]
Historical Development
3. Geographical distribution [2]
4. The plant formation [2]
5. Plant succession [3]
6. Ecological phytogeography [4]
7. Experimental ecology [4]
8. Ecology of the habitat [5]
9. The evidence from historical development [6]
Present Status of Ecology
10. The lack of special training [6]
11. Descriptive ecology [7]
12. The value of floristic [8]
13. Reconnaissance and investigation [8]
14. Resident investigation [9]
15. The dangers of a restricted field [9]
Applications of Ecology
16. The subjects touched by ecology [10]
17. Physiology and pathology [11]
18. Experimental evolution [11]
19. Taxonomy [12]
20. Forestry [14]
21. Physiography [15]
22. Soil physics [15]
23. Zoogeography [15]
24. Sociology [16]
THE ESSENTIALS OF A SYSTEM
25. Cause and effect: habitat and plant [16]
26. The place of function [17]
Chapter II. The Habitat
CONCEPT AND ANALYSIS
27. Definition of the habitat [18]
28. Factors [18]
Classification of Factors
29. The nature of factors [19]
30. The influence of factors [19]
Determination of Factors
31. The need of exact measurement [20]
32. The value of meteorological methods [20]
33. Habitat determination [21]
34. Determinable and efficient differences [21]
Instrumentation
35. Methods [22]
36. Method of simple instruments [22]
37. Method of automatic instruments [23]
38. Combined methods [23]
CONSTRUCTION AND USE OF INSTRUMENTS
39. The selection of instruments [24]
Water-content
40. Value of different instruments [25]
Geotome methods
41. The geotome [25]
42. Soil borers [26]
43. Taking samples of soil [26]
44. Weighing [27]
45. Computation [28]
46. Time and location of readings [28]
47. Location of readings [29]
48. Depth of samples [30]
49. Check and control instruments [30]
Physical and Physiological Water
50. The availability of soil water [30]
51. Terms [31]
52. Chresard determination under control [32]
53. Chresard readings in the field [33]
54. Chresard values of different soils [34]
Records and Results
55. The field record [35]
56. The permanent record [36]
57. Sums and means [36]
58. Curves [37]
Humidity
59. Instruments [37]
Psychrometers
60. Kinds [37]
61. The sling psychrometer [38]
62. Readings [39]
63. Cog psychrometer [39]
64. Construction and use [40]
65. Hygrometers [40]
Psychrographs
66. The Draper psychrograph [41]
67. Placing the instrument [42]
68. Regulating and operating the instrument [43]
69. The weekly visit [44]
Humidity Readings and Records
70. The time of readings [44]
71. Place and height [45]
72. Check instruments [45]
73. Humidity tables [46]
74. Sums, means, and curves [47]
Conversion scale for temperatures
75. Records [48]
Light
76. Methods [48]
The Photometer
77. Construction [49]
78. Filling the photometer [50]
79. Making readings [50]
80. The Dawson-Lander sun recorder [51]
81. The selagraph [52]
Standards
82. Use [53]
83. Making a standard [53]
84. Kinds of standards [54]
Readings
85. Time [55]
Chart for determining sun’s altitude [57]
86. Table for determining apparent noon [58]
87. Place [59]
Table of intensity at various angles [60]
Reflected and Absorbed Light
88. The fate of incident light [60]
89. Methods of determination [61]
90. Leaf and epidermis prints [62]
Expression of Results
91. Light records [63]
92. Light sums, means and curves [63]
Temperature
93. [64]
Thermometers
94. Air thermometers [64]
95. Soil thermometers [64]
96. Maximum-minimum thermometers [65]
97. Radiation thermometers [67]
98. Thermographs [67]
Readings
99. Time [69]
100. Place and height [70]
Expression of Results
101. Temperature records [70]
102. Temperature sums and means [70]
103. Temperature curves [71]
104. Plant temperatures [71]
Precipitation
105. General relations [72]
106. The rain gauge [73]
107. Precipitation records [74]
Wind
108. Value of readings [74]
109. The anemometer [75]
110. Records [76]
Soil
111. Soil as a factor [76]
112. The value of soil surveys [77]
113. The origin of soils [77]
114. The structure of soils [78]
115. Mechanical analysis [79]
116. Kinds of soils [79]
117. The chemical nature of soils [80]
Physiography
118. Factors [80]
Altitude
119. Analysis into factors [81]
120. The barometer [82]
Slope
121. Concept [83]
122. The clinometer [83]
123. The trechometer [84]
Exposure
124. Exposure [85]
125. Surface [85]
126. Record of physiographic factors [86]
127. Topography [86]
Biotic Factors
128. Influence and importance [86]
129. Animals [87]
130. Plants [87]
METHODS OF HABITAT INVESTIGATION
131. [88]
Method of Simple Instruments
132. Choice of stations [88]
133. Time of readings [89]
134. Details of the method [89]
135. Records [91]
Method of Ecograph Batteries
136. [92]
Expression of Physical Factor Results
137. The form of results [94]
Factor Records
138. [94]
Factor Curves
139. Plotting [95]
140. Kinds of curves [96]
141. Combinations of curves [96]
142. The amplitude of curves [98]
Factor Means and Sums
143. [98]
Chapter III. The Plant
STIMULUS AND RESPONSE
General Relations
144. The nature of stimuli [100]
145. The kinds of stimuli [100]
146. The nature of response [101]
147. Adjustment and adaptation [102]
148. The measurement of response [103]
149. Plasticity and fixity [104]
150. The law of extremes [105]
151. The method of working hypotheses [106]
Hydroharmose
Adjustment
152. Water as a stimulus [107]
153. The influence of other factors upon water [107]
154. Response [108]
155. The measurement of absorption [109]
156. The quantitative relation of absorption and transpiration [111]
157. Measurement of transpiration [113]
158. Field methods [114]
159. Expression of results [116]
160. Coefficient of transpiration [117]
Adaptation
161. Modifications due to water stimuli [118]
162. Modifications due to a small water supply [118]
163. The decrease of water loss [118]
164. The increase of water supply [121]
165. Modifications due to an excessive water supply [121]
166. Plant types [122]
167. Xerophytic types [122]
168. Types of leaf xerophytes [123]
169. Types of stem xerophytes [125]
170. Bog plants [126]
171. Hydrophytic types [127]
Photoharmose
Adjustment
172. Light as a stimulus [129]
173. The reception of light stimuli [131]
174. The response of the chloroplast [132]
175. Aeration and translocation [134]
176. The measurement of responses to light [135]
Adaptation
177. Influence of chloroplasts upon form and structure [138]
178. Form of leaves and stems [139]
179. Modification of the epidermis [140]
180. The differentiation of the chlorenchym [142]
181. Types of leaves [144]
182. Heliophytes and sciophytes [144]
EXPERIMENTAL EVOLUTION
183. Scope [145]
184. Fundamental lines of inquiry [146]
185. Ancestral form and structure [146]
186. Variation and mutation [147]
187. Methods [149]
Method of Natural Experiment
188. Selection of species [149]
189. Determination of factors [151]
190. Method of record [152]
Method of Habitat Cultures
191. Scope and advantages [153]
192. Methods [153]
193. Transfer [154]
194. Modification of the habitat [156]
Method of Control Cultures
195. Scope and procedure [157]
196. Water-content series [158]
197. Light series [160]
Chapter IV. The Formation
METHODS OF INVESTIGATION AND RECORD
198. The need of exact methods [161]
Quadrats
199. Uses [161]
200. Possible objections [163]
Kinds of Quadrats and Their Use
201. Size and kinds [164]
202. Tapes and stakes [164]
203. Locating quadrats [165]
The List Quadrat
204. Description [165]
205. Manner of use [166]
206. Table of abundance [166]
The Chart Quadrat
207. Description and use [167]
208. The chart [168]
209. Mapping [168]
210. Factors and photographs [170]
The Permanent Quadrat
211. Description and uses [170]
212. Manner of use [172]
The Denuded Quadrat
213. Description [173]
214. Methods of denuding and recording [174]
215. Physical factors [175]
Aquatic Quadrats
216. Scope [175]
Transects
217. The transect [176]
The Line Transect
218. Description and method [176]
219. The location and size [177]
The Belt Transect
220. Details [178]
The Permanent Transect
221. Advantages [179]
222. Details [179]
The Denuded Transect
223. [180]
The Layer Transect
224. [180]
Ecotone Charts
225. [181]
The Migration Circle
226. Purpose [182]
227. Location and method [182]
228. The denuded circle [183]
229. Photographs [183]
Cartography
230. Value of cartographic methods [183]
231. Standard scale [184]
232. Color scheme [184]
233. Formation and vegetation maps [185]
234. Continental maps [187]
Photography
235. [188]
236. The camera and its accessories [188]
237. The choice of a camera [190]
238. The use of the camera [191]
239. The sequence of details [192]
240. The time of exposure [193]
241. Developing [194]
242. Finishing [195]
Formation and Succession Herbaria
243. Concept and purpose [196]
244. Details of collecting [197]
245. Arrangement [197]
246. Succession herbaria [198]
DEVELOPMENT AND STRUCTURE
247. Vegetation an organism [199]
248. Vegetation essentially dynamic [199]
249. Functions and structures [199]
Association
250. Concept [200]
251. Causes [201]
252. Aggregation [203]
Kinds of Association
253. Categories [204]
254. Stratum association [204]
255. Ground association [205]
256. Species guild association [206]
257. Light association [206]
258. Water-content association [208]
THE DEVELOPMENT OF THE FORMATION
259. [210]
Invasion
260. [210]
Migration
261. [210]
262. Mobility [211]
263. Organs for dissemination [211]
264. Contrivances for dissemination [212]
265. Position of disseminules [214]
266. Seed production [215]
267. Agents of migration [216]
268. The direction of migration [219]
Ecesis
269. Concept [220]
270. Germination of the seed [221]
271. Adjustment to the habitat [223]
Barriers
272. Concept [224]
273. Physical barriers [225]
274. Biological barriers [225]
275. Influence of barriers [226]
Endemism
276. Concept [227]
277. Causes [228]
278. Significance [228]
Polyphylesis and Polygenesis
279. Concept [230]
280. Proofs of polygenesis [231]
281. Origin by polyphylesis [232]
Kinds of Invasion
282. Continuous and intermittent invasion [234]
283. Complete and partial invasion [235]
284. Permanent and temporary invasion [235]
Manner of Invasion
285. Entrance into the habitat [236]
286. Influence of levels [238]
Investigation of Invasion
287. [239]
Succession
288. Concept [239]
289. Kinds of succession [240]
Primary Successions
290. [241]
291. Succession through elevation [241]
292. Succession through volcanic action [242]
293. Weathering [243]
294. Succession in residuary soils [243]
295. Succession in colluvial soils [244]
296. Succession in alluvial soils [245]
297. Succession in aeolian soils [246]
298. Succession in glacial soils [247]
Secondary Successions
299. [247]
300. Succession in eroded soils [247]
301. Succession in flooded soils [248]
302. Succession by subsidence [249]
303. Succession in land slips [249]
304. Succession in drained or dried soils [249]
305. Succession by animal agency [250]
306. Succession by human agency [250]
307. Succession in burned areas [251]
308. Succession in lumbered areas [252]
309. Succession by cultivation [253]
310. Succession by drainage [253]
311. Succession by irrigation [253]
312. Anomalous successions [254]
313. Perfect and imperfect successions [254]
314. Stabilization [255]
Causes and Reactions
315. [256]
316. Succession by preventing weathering [257]
317. Succession by binding aeolian soils [258]
318. Succession by reducing run-off and erosion [259]
319. Succession by filling with silt and plant remains [260]
320. Succession by enriching the soil [261]
321. Succession by exhausting the soil [262]
322. Succession by the accumulation of humus [263]
323. Succession by modifying atmospheric factors [264]
Laws of Succession
324. [264]
Classification and Nomenclature
325. Basis [267]
326. Nomenclature [267]
327. Illustrations [270]
Investigation of Succession
328. General rules [270]
329. Method of alternating stages [271]
330. The relict method [272]
THE STRUCTURE OF THE FORMATION
331. [274]
Zonation
332. Concept [274]
Causes of Zonation
333. Growth [275]
334. Reactions [276]
335. Physical factors [276]
336. Physiographic symmetry [278]
Kinds of Zonation
337. [279]
338. Radial zonation [280]
339. Bilateral zonation [280]
340. Vertical zonation [280]
341. Vegetation zones [281]
Alternation
342. Concept [283]
343. Causes [284]
344. Competition [285]
345. Kinds of alternation [289]
The Formation in Detail
346. The rank of the formation [292]
347. The parts of a formation [295]
348. Nomenclature of the divisions [299]
349. The investigation of a particular formation [299]
Classification and Relationship
350. Basis [300]
351. Habitat classification [301]
352. Nomenclature [302]
353. Developmental classification [304]
354. Regional classification [304]
355. Mixed formations [304]
EXPERIMENTAL VEGETATION
356. Scope and methods [306]
Method of Natural Habitats
357. Natural experiments [307]
Method of Artificial Habitats
358. Modification of habitat [307]
359. Denuding [308]
360. Modification of the formation by transfer [309]
Method of Control Habitats
361. Competition cultures [310]
362. Details of culture methods [311]
Glossary [314]
Bibliography [324]

RESEARCH METHODS IN ECOLOGY

CHAPTER I. THE FOUNDATION OF ECOLOGY
The Need of a System

1. The scope of ecology. The clue to the field of ecology is found in the Greek word, οἲκος, home. The point of view in the following treatise is constantly that which is inherent in the term itself. Ecology is therefore considered the dominant theme in the study of plants, indeed, as the central and vital part of botany. This statement may at first appear startling, if not unfounded, but mature reflection will show that all the questions of botanical science lead sooner or later to the two ultimate facts: plant and habitat. The essential truth of this has been much obscured by detached methods of study in physiology, morphology, and histology, which are too often treated as independent fields. These have suffered incomplete and unsymmetric development in consequence of extreme specialistic tendencies. Analytic methods have dominated research to the exclusion of synthetic ones, which, in a greatly diversified field, must be final, if botanical knowledge is something to be systematized and not merely catalogued. Physiology in particular has suffered at the hands of detached specialists. Originally conceived as an inquiry into the origin and nature of plants, it has been developed strictly as a study of plant activities. It all but ignores the physical factors that control function, and the organs and tissues that reflect it.

2. Ecology and physiology. There can be little question in regard to the essential identity of physiology and ecology. This is evident when it is clearly seen that the present difference between the two fields is superficial. Ecology has been largely the descriptive study of vegetation; physiology has concerned itself with function; but, when carefully analyzed, both are seen to rest upon the same foundation. In each, the development is incomplete: ecology has so far been merely superficial, physiology too highly specialized. The one is chaotic and unsystematized, the other too often a minute study of function under abnormal circumstances. The greatest need of the former is the introduction of method and system, of the latter, a broadening of scope and new objectives. The growing recognition of the identity of the two makes it desirable to anticipate their final merging, and to formulate a system that will combine the good in each, and at the same time eliminate superficial and extreme tendencies. In this connection, it becomes necessary to point out to ecologist and physiologist alike that, while they have been working on the confines of the same great field, each must familiarize himself with the work and methods of the other, before his preparation is complete. Both must broaden their horizons, and rearrange their views. The ecologist is sadly in need of the more intimate and exact methods of the physiologist: the latter must take his experiments into the field, and must recognize more fully that function is but the middleman between habitat and plant. It seems probable that the final name for the whole field will be physiology, although the term ecology has distinct advantages of brevity and of meaning. In this event, however, it should be clearly recognized that, although the name remains the same, the field has become greatly broadened by new viewpoints and new methods.