Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

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Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: 3 Spectral signatures of objects. Chairman: G. Guyot, Liaison: N. J. J. Bunnik

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: The application of a vegetation index in correcting the infrared reflectance for soil background. J. G. P. W. Clevers

Document type:: Multivolume work

Structure type:: Chapter

225 ation of the •ibed by equa- lation of the the ratio of ind of infra- the soil at l to one. The ition in the 1 explicitly. 1 to be a more ared reflec- :e the actual various spec- method 1 com- ¡asurements in rhich the green ) for calcu- nce, whereas 1 reflectances (1 and 2) may tance cannot the recording s explicitly Results for le 2 and fi- 2 gave sim arse results is indicates ail reflec- !S. The con- id by method 2 d 0 or 1 was i of LAI is asymptotic :ance, and it .g. from a is an ex- ¥s in consid- .ues, but with LAI Figure 3: Regression of LAI on corrected infrared reflectance, using method 0. Field trial 116, vege tative stage, 1982. LAI Figure 4: Regression of LAI on corrected infrared reflectance, using method 1. Field trial 116, vege tative stage, 1982. LAI the regres- .ectance for it measure- esulting in did not vary : of the curve, ¡reals and in leasurements malysis of er treatment nteractions ients (LAI), 1 out on re- i spectral itter vari- ;ly smaller can be as- ;ans of con- sis of vari- ¡timated LAI results of ile with the riginal LAI ime variable. :or correcting :ly estimating efficient of 1 of [duals figure .217 3 .230 4 .214 5 Figure 5: Regression of LAI on corrected infrared reflectance, using method 2. Field trial 116, vege tative stage, 1982. Table 3 lists the means, estimated coefficients of variation (CV) of residuals and the critical levels in testing for treatment effects for the LAI (field measurements) during the vegetative stage of the crop, resulting from an analysis of variance. The variance was determined by means of appropriate averaging of inter-plot and intra-plot variances. The CV is the ratio of the square root of the mean squares of residuals and the mean value of the de pendent variable. The critical level (often called P-value) is the smallest level of significance at which the observed result would just lead to rejec tion of the null hypothesis (that a treatment has no effects). On 19 May the interaction effect between sowing date and nitrogen nutrition was significant at the 5 % level (meaning that the effects of nitro gen nutrition were dependent on the sowing date). The nitrogen nutrition effect was significant on 17 June. The results of the analysis of variance for the infrared reflectance data obtained are listed in table 4 (the infrared reflectance relates best to LAI). On most dates, critical levels in testing for treatment effects by means of infrared reflectance measurements were smaller than those obtained by means of LAI measurements, with the exception of a large critical level for sowing date effect on 10 June. Thus treatment effects could be ascertain ed with larger power with reflectance measurements than with LAI determination in the field. This is the main reason for preferring reflectance measure ments over sampling in field trials. This conclu sion is also confirmed by the magnitude of the co efficients of variation. CV values in the infrared band were considerably smaller than CV values for LAI. However, one has to keep in mind that infra red reflectance and LAI are different characteris tics and therefore one should be careful when com paring these results. With the results of table 2 it is possible to estimate the LAI per plot from the reflectance mea surements (method 2) and subsequently to apply an analysis of variance on these LAI estimates. The results of such an analysis of variance are listed in table 5. Results for 28 April 1982 are not list ed, because bare soil predominated on that date. Similarly to the results for the infrared reflec tance, the critical levels in testing for treatment effects in LAI estimates were smaller than those in the LAI measurements (table 3) on most dates. Thus, treatment effects on LAI could be ascertained with larger power by reflectance measurements than by taking samples in the field. This was confirmed by Table 3: LAI: means, CVs and critical levels in testing for treatment effects, obtained on conse cutive sampling dates. Field trial 116 in 1982. date mean CV critical interaction level in sowing dates testing: nitrogen nutrition 19 May 0.99 0.215 0.030 0.003 0.011 3 June 3.67 0.363 0.474 0.092 0.277 17 June 5.27 0.256 0.920 0.123 0.004 Table 4: critical obtained in 1982. Infrared reflectance (%): means, CVs and levels in testing for treatment effects, on consecutive missions. Field trial 116 date mean CV critical interaction level in sowing dates testing: nitrogen nutrition 28 April 13.8 0.056 0.587 0.012 0.885 17 May 15.4 0.021 0.003 0.001 0.001 27 May 33.6 0.034 0.000 0.001 0.000 10 June 47.9 0.071 0.864 0.465 0.001 17 June 53.0 0.033 0.565 0.013 0.000 Table 5: LAI estimated by reflectance measurements: means, CVs and critical levels in testing for treat ment effects, obtained on consecutive missions. Field trial 116 in 1982. date mean CV critical level in testing: interaction sowing nitrogen dates nutrition 17 May 0.48 0.099 0.000 0.002 0.000 27 May 2.42 0.075 0.000 0.001 0.000 10 June 4.47 0.152 0.906 0.814 0.002 17 June 5.70 0.073 0.279 0.110 0.000

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