173:
applications involving gradsects have ranged from habitat suitability studies of fungi (Shearer and Crane 2011 ), termites (Gillison et al. 2003) other macro invertebrates (Lawes et al. 2005 ); birds (Damalas 2005) small and large mammals (Laurance 1994; Ramono et al. 2009). Vegetation studies using gradsects have been widely applied in many countries ranging from tidal wetlands (Parker et al. 2011) and agricultural cropping systems and forested landscape mosaics (Gillison et al. 2004) to infectious diseases (Boone et al. 2000 ). At broader geographic and national scales (Grossman et al., 1998, 2007; USA/NPS 2012) gradsects have been applied to guide field sampling and forest mapping in mountainous terrain (Sandman and
Lertzmann 2003) as well as wide-ranging
159:
design (see
Applications next). Apart from improved logistic efficiency, the gradsect method seeks to maximise environmental representativeness which has the dual advantage of potentially improving location of rarities and enhancing spatial modelling of species distribution. Because the underlying
124:
or local land use farming system or finer scale gradient levels representing local vegetational sequences. Through an inspection of spatial overlays of all gradients, a minimum number of sample locations is then purposively located to reflect, as far as possible, total environmental variation. For
76:
provided a reference platform for developing and testing a less logistically demanding and yet statistically acceptable gradient-based survey design that avoided the need for random or purely grid-based sampling. These initial studies and subsequently developed statistical support for purposive,
172:
Since the publication of gradsect theory in 1984, subsequent vegetational and landscape studies in regional
Australia (Austin and Heyligers 1989); Ludwig and Tongway (1995) were followed by a successful evaluation of the method in faunal surveys in South Africa (Wessels et al.). Since then
129:
gradsect is constructed that may then be modified to accommodate logistic tradeoffs. The selection discipline requires that the fullest possible range of each hierarchical level is sampled. This commonly results in a set of progressively nested clusters of sample sites contained within the
56:(1967) and others. Although in practice, life-scientists intuitively sample gradients, until the early 1980s there was little formal theoretical or empirical support for such an approach, sample design being driven largely by traditional statistical methods based on
130:
overarching primary gradient that may not reflect a linear distribution. At relatively local landscape scale, a primary gradients may be represented by salinity levels or water depth as in tidal wetlands or micro-topographic relief as in forest margins or a
146:
Initial studies in gradsect development revealed considerable logistic and other advantages over more traditional non-gradient-based survey designs concerned primarily with random sampling. This finding is now widely supported especially in
479:
Rocchini, D., McGlinn, D., Ricotta, C., Neteler, M. and
Wohlgemuth, T. (2011). Landscape complexity and spatial scale influence the relationship between remotely sensed spectral diversity and survey-based plant species richness
44:
or systematic (e.g. grid-based) systems tend to be less efficient in recovering information about the distribution of taxa than sample designs that are purposively directed instead along deterministic environmental gradients.
305:
Gillison, A.N., Jones, D.T., Susilo, F-X. and
Bignell, D.E. (2003). Vegetation indicates diversity of soil macroinvertebrates: a case study with termites along a land-use intensification gradient in lowland Sumatra.
396:
Boone, J.D., McGuire, K.C., Otteson, E.W., DeBaca, R.S., Kuhn, E.A., Villard, P.F. & St Jeor, S.C. (2000). Remote
Sensing and Geographic Information Systems: Charting Sin Nombre Virus Infections in Deer Mice.
91:
In constructing a gradsect, existing information is initially reviewed in which a hierarchy of environmental gradients is first identified either by visual means (maps, aerial photographs etc..) or through
164:, gradsect sampling cannot be used to estimate numbers of species or other biological attributes per unit area. For that purpose some measure of random sampling needs to be built into the sample design.
466:
Mallinis, G., Koutsias, N., Tsakiri-Strati, M. and
Karteris, M. (2008). Object-based classification using Quickbird imagery for delineating forest vegetation polygons in a Mediterranean test site.
427:. NatureServe In Cooperation with the California Native Plant Society and California Natural Heritage Program Wildlife and Habitat Data Analysis Branch California Department of Fish and Game.
134:. For most practical purposes, transects are commonly laid out along contours perpendicular to the main direction of the gradient. Iterative spatial analysis of environmental layers over a
453:
Sandmann, H. and
Lertzman, K.P. (2003). Combining high-resolution aerial photography with gradient-directed transects to guide field sampling and forest mapping in mountainous terrain.
380:
Gillison, A.N., Liswanti, N. Budidarsono, S., van
Noordwijk, M. and Tomich, T.P. (2004). Impact of cropping methods on biodiversity in coffee agroecosystems in Sumatra, Indonesia.
410:
Grossman, D. H., Faber-Langendoen, D., Weakley, A.S. et al. (1998). International classification of ecological communities: terrestrial vegetation of the United States. Vol. I,
319:
Lawes, M.J., Kotze, D.J., Bourquin, S.L. and Morris, C. (2005). Epigaeic invertebrates as potential ecological indicators of afromontane forest condition in South Africa.
83:
was coined that coupled purposive, transect sampling with a hierarchical framework of environmental gradients considered to be key determinants of species distribution.
332:
Damalas, A. (2005). Landscape ecology of birds on Mount
Leconte, Great Smoky Mountains National Park Dissertation. Old Dominion University. 358 pages; AAT 3195595.
354:
Ramono, W., Isnan, M.W., Sadjudin, H.R., Gunawan, H., Dahlan, E.N., Sectionov, Pairah, Hariyadi, A.R., Syamsudin, M., Talukdar, B.K. & Gillison, A.N. (2009).
367:
Parker, V.T., L. M. Schile, M.C. Vasey, and J.C. Callaway. (2011). Efficiency in assessment and monitoring methods: scaling down gradient-directed transects.
288:
Shearer, B.L. and Crane, C.E. (2011). Habitat suitability of soils from a topographic gradient across the Fitzgerald River National Park for invasion by
249:
Austin, M.P. and Heyligers, P.C. (1989). Vegetation survey design for conservation: gradsect sampling of forests in northeastern New South Wales;
206:
Gillison, A.N. (1984). Gradient oriented sampling for resource surveys – the gradsect method. In: K.R. Myers, C.R. Margules and I. Musto (eds.)
125:
logistic and other purposes (such as improving the capacity to locate rare species) the steepest gradients are usually selected. In this way an
425:
Classification of the Vegetation of Yosemite National Park and Surrounding Environs in Tuolumne, Mariposa, Madera and Mono Counties, California
275:
Wessels, K.J., Van Jaarsveld, A.S., Grimbeek, J.D. & Van der Linde, M.J. (1998). An evaluation of the gradsect biological survey method.
77:
gradient-based survey provided a formalized, practical alternative to more logistically demanding traditional designs. It was here the term
210:
pp. 349–74. Proc. Workshop held at Adelaide Univ. 31 Aug. to 31 Sept. 1983. (CSIRO (Aust.) Division of Water and Land Resources, Canberra)
262:
Ludwig, J.A. and Tongway, D.J. (1995). Spatial organization of landscapes and its function in semi-arid woodlands, Australia.
510:
219:
Gillison, A.N. and Brewer, K.R.W. (1985) The use of gradient directed transects or gradsects in natural resource surveys.
356:
Report on a second habitat assessment for the Javan rhinoceros (Rhinoceros sondaicus sondaicus) within the island of Java
505:
500:
53:
341:
Laurance, W.F. (1994). Rainforest Fragmentation and the Structure of Small Mammal Communities in Tropical Queensland.
138:
can then be used to identify areas requiring additional sampling thereby improving environmental representativeness.
100:
of institutional or other data sources. A typical regional gradsect for example may be constructed according to a
33:
24:
is a low-input, high-return sampling method where the aim is to maximise information about the distribution of
152:
135:
439:
49:
232:
Gillison, A.N. (2013). Plant Functional Types and Traits at the Community, Ecosystem and World Level, in
52:
based approaches to better understand community dynamics and this is reflected especially in the work of
156:
237:
161:
93:
57:
97:
61:
41:
29:
25:
174:
494:
131:
121:
109:
412:
The National Vegetation Classification System: development, status, and applications
148:
385:
37:
240:
and J. Franklin), John Wiley & Sons, Ltd, Oxford, UK. Ch 12, pp.347-386.
113:
73:
423:
Grossman, D., Drake, J., Schindel, M., Hickson, D. et al. (2007).
32:, their placement being largely determined by a hierarchy of
177:
applications (Mallinis et al. 2008; Rocchini et al. 2011 ).
193:
Whittaker R. H. (1967). Gradient analysis of vegetation.
48:
Ecologists have long been aware of the significance of
28:
in any area of study. Most living things are rarely
414:. The Nature Conservancy, Arlington, Virginia, USA.
468:ISPRS Journal of Photogrammetry and Remote Sensing
386:http://www.ecologyandsociety.org/vol9/iss2/art7
72:Intensively sampled landscape-based surveys in
8:
104:(temperature, moisture, seasonality) then a
442:/Rio Grande National Wild and Scenic River
186:
116:, major and minor drainage systems), a
208:Survey Methods for Nature Conservation
438:Gradsect and Field Sampling Plan for
120:possibly represented by a local soil
7:
308:Organisms Diversity & Evolution
221:Journal of Environmental Management
36:factors. For this reason, standard
436:National Park Service USA (2012).
160:statistical model is not based on
14:
358:. International Rhino Foundation.
482:Journal of Vegetation Science.
1:
277:Biodiversity and Conservation
399:Emerging Infectious Diseases
294:Australasian Plant Pathology
527:
142:Advantages and limitations
22:gradient-directed transect
102:primary climate gradient
343:Biological Conservation
251:Biological Conservation
153:environmental surveying
136:digital elevation model
440:Big Bend National Park
290:Phytophthora cinnamomi
236:, Second Edition (eds
50:environmental gradient
511:Ecological techniques
30:distributed at random
506:Sampling techniques
501:Biological censuses
382:Ecology and Society
151:and other areas of
38:statistical designs
234:Vegetation Ecology
195:Biological Reviews
162:probability theory
106:secondary gradient
94:numerical analysis
58:probability theory
264:Landscape Ecology
238:E. van der Maarel
118:tertiary gradient
518:
485:
477:
471:
464:
458:
451:
445:
434:
428:
421:
415:
408:
402:
394:
388:
378:
372:
365:
359:
352:
346:
339:
333:
330:
324:
317:
311:
303:
297:
286:
280:
273:
267:
260:
254:
247:
241:
230:
224:
217:
211:
204:
198:
191:
98:spatial analysis
54:Robert Whittaker
40:based on purely
526:
525:
521:
520:
519:
517:
516:
515:
491:
490:
489:
488:
478:
474:
465:
461:
452:
448:
435:
431:
422:
418:
409:
405:
395:
391:
379:
375:
366:
362:
353:
349:
340:
336:
331:
327:
318:
314:
304:
300:
287:
283:
279:. 7: 1093–1121.
274:
270:
261:
257:
248:
244:
231:
227:
218:
214:
205:
201:
192:
188:
183:
170:
144:
89:
70:
62:random sampling
42:random sampling
12:
11:
5:
524:
522:
514:
513:
508:
503:
493:
492:
487:
486:
472:
470:. 63: 237–250.
459:
455:Forest Science
446:
429:
416:
403:
389:
373:
360:
347:
334:
325:
312:
298:
281:
268:
255:
242:
225:
212:
199:
185:
184:
182:
179:
175:remote sensing
169:
166:
143:
140:
88:
85:
69:
66:
60:incorporating
13:
10:
9:
6:
4:
3:
2:
523:
512:
509:
507:
504:
502:
499:
498:
496:
483:
476:
473:
469:
463:
460:
456:
450:
447:
443:
441:
433:
430:
426:
420:
417:
413:
407:
404:
400:
393:
390:
387:
383:
377:
374:
370:
364:
361:
357:
351:
348:
344:
338:
335:
329:
326:
322:
316:
313:
310:. 3: 111–126.
309:
302:
299:
295:
291:
285:
282:
278:
272:
269:
265:
259:
256:
252:
246:
243:
239:
235:
229:
226:
222:
216:
213:
209:
203:
200:
196:
190:
187:
180:
178:
176:
167:
165:
163:
158:
154:
150:
141:
139:
137:
133:
132:riparian zone
128:
123:
119:
115:
111:
110:geomorphology
107:
103:
99:
95:
86:
84:
82:
81:
75:
67:
65:
63:
59:
55:
51:
46:
43:
39:
35:
34:environmental
31:
27:
23:
19:
484:22: 688–698.
481:
475:
467:
462:
457:49: 429–443.
454:
449:
437:
432:
424:
419:
411:
406:
398:
392:
384:9: 7. URL:
381:
376:
368:
363:
355:
350:
345:. 69: 23–32.
342:
337:
328:
323:37; 109–118.
320:
315:
307:
301:
296:40: 168–179.
293:
289:
284:
276:
271:
266:. 10: 51–63.
263:
258:
250:
245:
233:
228:
223:20; 103–127.
220:
215:
207:
202:
197:42: 207–264.
194:
189:
171:
168:Applications
157:conservation
149:biodiversity
145:
126:
117:
105:
101:
90:
79:
78:
71:
47:
21:
17:
15:
401:6: 248–258.
87:Methodology
495:Categories
321:Biotropica
253:50: 13–32.
181:References
369:Ecosphere
114:lithology
74:Australia
80:gradsect
18:gradsect
444:.(Book)
371:. 2: 99
68:Origins
122:catena
127:ideal
26:biota
155:and
96:or
20:or
497::
292:.
112:,
64:.
16:A
108:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.