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