Microclimate and thermal comfort indices in silvopastoral systems under different planting directions and seasons

Carvalho, Rafael P. de; Heid, Debora M.; Davide, Livia M. C.; Piletti, Ligia M. M. da S.; Jesus, Fernanda L. F. de; Viegas Neto, Antonio L.

doi:10.1590/1807-1929/agriambi.v24n4p266-273

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Articles • Rev. bras. eng. agríc. ambient. 24 (4) • Apr 2020 • https://doi.org/10.1590/1807-1929/agriambi.v24n4p266-273 copy

Microclimate and thermal comfort indices in silvopastoral systems under different planting directions and seasons

Microclima e índices de conforto térmico em sistemas silvipastoris sob diferentes direções de plantio e estações

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The orientation of tree-rows in a silvopastoral system associated with different seasons of the year allows more or less sunlight penetration, resulting in deliberate modification of the microclimate composition and thermal conditions provided to animals. In this sense, the aims of this study were to evaluate microclimatic variables and thermal comfort indices for east-west and north-south oriented silvopastoral systems, compared to unshaded systems during summer and winter. The study was conducted at the Modelo II Farm (21° 08’ S 53° 17’ W) at an altitude of 354 m. A randomized block design in scheme of split-split plots with five repetitions was adopted. Two planting directions and a control treatment (unshaded) were evaluated in the plots. Collection times were evaluated in sub-plots, and the distance from eucalyptus trees was evaluated in sub-sub-plots. Changes in the east-west and north-south planting directions did not promote changes in climate variables, nor did they change the thermal comfort indices during summer. There were differences, however, in temperature and relative humidity of the air, black globe temperature, and radiant heat load during winter. Silvopastoral systems provide improvements in the environment and, concomitantly, to the thermal comfort of animals, when compared to unshaded systems. However, thermal stress situations occur despite the presence of trees, depending on the time of the day and the distance from the rows of eucalyptus trees.

Key words:
thermal stress; shading; seasons; eucalyptus

Treatment Seasons	At (°C)		RH (%)		Gt (°C)		S (m s^-1)		THI		BGHI		H (kJ kg^-1)		RHL (W m^-2)
Summer/2012	31.7	a	49.2	ab	38.3	a	3.7	a	79.3	a	85.9	a	88.2	a	714.2	a
Winter/2012	27.6	b	43.0	b	32.7	b	4.4	a	72.9	b	79.1	b	69.1	b	580.4	b
Summer/2013	30.1	a	53.3	a	36.9	ab	2.5	a	77.8	a	84.2	a	84.4	a	663.4	ab
Winter/2013	26.3	b	43.6	b	31.3	b	2.8	a	71.4	b	77.2	b	66.6	b	589.9	b
SPS	Summer
SPS/EW	30.9	b	49.7	a	37.3	b	3.3	a	78.1	b	86.9	b	84.5	b	702.4	b
SPS/NS	30.1	b	51.5	a	36.1	b	2.6	a	77.8	b	85.5	b	83.9	b	667.2	b
UPS	32.8	a	44.3	b	40.6	a	4.7	a	81.2	a	89.4	a	92.8	a	766.7	a
	Winter
SPS/EW	24.8	c	46.1	c	29.1	c	2.7	a	71.8	b	79.1	b	66.8	b	577.6	c
SPS/NS	26.9	b	41.2	b	32.4	b	3.1	a	72.4	b	78.8	b	68.7	b	592.0	b
UPS	28.0	a	35.0	a	35.2	a	3.4	a	75.8	a	81.6	a	72.7	a	686.0	a
Significance	Summer
Orientation (Orient)	ns		ns		ns		ns		ns		ns		ns		ns
Time (Time)	##		#		##		#		#		##		#		##
Orient × Time	ns		ns		ns		ns		ns		ns		ns		ns
Distance (Dis)	##		#		#		ns		#		#		#		#
Orient × Dis	*		ns		*		ns		ns		*		ns		*
Time × Dis	*		*		**		ns		ns		**		ns		**
Orient × Time × Dis	ns		ns		ns		ns		ns		ns		ns		ns
CV_plot (%)	7.98		13.90		18.72		33.42		7.98		12.93		16.12		23.06
CV_sub-plot (%)	20.91		28.10		21.98		50.89		11.98		15.92		7.91		20.95
CV_sub-sub-plot (%)	8.32		6.98		14.26		14.18		6.98		9.23		2.29		10.22
Significance	Winter
Orientation (Orient)	*		*		*		ns		ns		ns		ns		*
Time (Time)	##		#		##		#		#		##		#		##
Orient × Time	ns		ns		ns		ns		ns		ns		ns		ns
Distance (Dis)	#		#		# #		ns		##		##		##		##
Orient × Dis	**		**		*		ns		*		*		*		*
Time × Dis	*		*		*		ns		*		*		*		*
Orient × Time × Dis	ns		ns		ns		ns		ns		ns		ns		ns
CV_plot (%)	5.87		11.87		15.90		41.65		5.24		9.42		10.32		26.91
CV_sub-plot (%)	19.40		33.80		20.40		75.91		10.41		11.92		6.91		21.65
CV_sub-sub-plot (%)	7.94		3.87		13.93		20.10		3.98		4.32		4.12		13.72

Orientation	Distance (m)												Regression	R²
Orientation	1		4		8		12		16		20		Regression	R²
Air temperature (°C)
SPS/EW	29.6	a	31.9	a	31.8	a	31.6	a	30.7	a	28.3	b	$y = 29.387 + 0.5896 * x - 0.0322 * * x^{2}$	0.93
SPS/NS	28.6	b	29.7	b	30.5	a	30.8	a	30.3	a	30.2	a	$y = 28.352 + 0.3699 * * x - 0.0143 * x^{2}$	0.91
Black globe temperature (°C)
SPS/EW	37.9	a	39.7	a	40.4	a	39.9	a	38,5	a	36.0	a	$y = 37.44 + 0.6545 * * x - 0.0365 * * x^{2}$	0,99
SPS/NS	33.3	b	33.8	b	37.3	b	37.4	a	37.8	a	37.7	a	$y = 32.252 + 0.7036 * x - 0 . 0217^{n s} x^{2}$	0.92
Black globe humidity index (BGHI)
SPS/EW	87.0	a	88.9	a	89.8	a	89.1	a	87.9	a	85.2	a	$y = 86.5 + 0.7007 * * x - 0.0384 * * x^{2}$	0.98
SPS/NS	82.4	b	83.0	b	86.5	b	86.6	a	87.1	a	86.9	a	$y = 81.344 + 0.7253 * x - 0 . 0225^{n s} x^{2}$	0.92
Enthalpy (H)
SPS	82.8		83.7		84.8		84.8		84.6		84.4		$y = 82.501 + 0.3647 * * x - 0.0138 * x^{2}$	0.95
Radiant heat load (RHL)
SPS/EW	726	a	795	a	801	a	762	a	755	a	658	a	$y = 720.2 + 18.152 * x - 1.0573 * x^{2}$	0.90
SPS/NS	590	b	607	b	713	b	703	b	695	a	685	a	$y = 559.59 + 21.913 * x - 0 . 7959^{n s} x^{2}$	0.86

Systems	Time (h)								Regression	R²
Systems	8		11		14		17		Regression	R²
Black globe temperature (°C)
SPS	25.4	a	40.3	a	44.3	b	37.7	b	$y = - 2.5531 + 33.6056 * * x - 5.8639 * * x^{2}$	0.99
UPS	27.8	a	43.5	a	48.9	a	44.3	a	$y = - 8.7288 + 44.9075 * * x - 8.6609 * * x^{2}$	0.99
Wind speed (m s^-1)
SPS	0.17	a	2.87	b	3.08	b	1.92	a	$y = - 15.812 + 2 . 8626^{n s} x - 0 . 1072^{n s} x^{2}$	0.98
UPS	0.24	a	6.89	a	5.35	a	3.06	a	$y = - 35.007 + 6 . 439^{n s} x - 0 . 2483^{n s} x^{2}$	0.88
Temperature and humidity index (THI)
SPS	71.2	a	79.2	a	83.2	b	78.1	b	$y = 14.869 + 9 . 9206^{n s} x - 0 . 3639^{n s} x^{2}$	0.98
UPS	73.5	a	81.0	a	87.7	a	81.3	a	$y = 12.347 + 10 . 656^{n s} x - 0 . 3861^{n s} x^{2}$	0.92
Black globe humidity index (BGHI)
SPS	73.7	a	90.0	a	95.2	b	90.2	b	$y = - 21.308 + 16.615 * * x - 0.5917 * * x^{2}$	0.99
UPS	75.6	a	92.6	a	99.7	a	94.9	a	$y = - 24.189 + 17.306 * x - 0.6056 * x^{2}$	0.99
Enthalpy (H)
SPS	71.9	a	87.2	a	93.6	b	84.8	b	$y = - 31.486 + 18 . 239^{n s} x - 0 . 6694^{n s} x^{2}$	0.99
UPS	71.5	a	92.8	a	101.6	a	92.2	a	$y = - 63.669 + 23.683 * x - 0.8528 * x^{2}$	0.99
Radiant heat load (RHL)
SPS	464	a	798	b	901	b	670	b	$y = - 1867.9 + 416.39 * x - 15.694 * x^{2}$	0.99
UPS	471	a	921	a	984	a	1027	a	$y = - 655.22 + 42.111 * x - 1.1111 * x^{2}$	0.99

Orientation	Distance (m)												Regression	R²
Orientation	1		4		8		12		16		20		Regression	R²
Air temperature (°C)
SPS/EW	27.0	a	27.4	a	26.7	a	25.4	b	24.5	b	24.5	b	$y = 27.524 - 0 . 1352^{n s} x - 0 . 0016^{n s} x^{2}$	0.89
SPS/NS	26.6	a	26.7	a	27.2	a	27.8	a	27.5	a	26.9	a	$y = 26.195 + 0 . 2213^{n s} x - 0 . 009^{n s} x^{2}$	0.81
Air relative humidity (%)
SPS/EW	42.7	b	42.2	b	44.0	a	47.5	a	48.8	a	46.7	a	$y = 40.928 + 0 . 678^{n s} x - 0 . 0171^{n s} x^{2}$	0.78
SPS/NS	46.4	a	46.5	a	45.3	a	44.4	a	42.5	b	44.0	a	$y = 47.223 - 0 . 342^{n s} x + 0 . 0075^{n s} x^{2}$	0.79
Black globe temperature (°C)
SPS/EW	30.5	a	32.2	a	32.8	a	30.9	a	27.6	b	27.0	b	$y = 30.70 + 0 . 3969^{n s} x - 0 . 0312^{n s} x^{2}$	0.85
SPS/NS	27.6	b	29.1	b	29.7	b	30.4	a	31.0	a	30.7	a	$y = 27.34 + 0 . 4098^{n s} x - 0 . 012^{n s} x^{2}$	0.97
Temperature and humidity index (THI)
SPS/EW	71.6	a	72.2	a	72.2	a	70.1	b	69.3	b	69.6	b	$y = 72.176 - 0 . 077^{n s} x - 0 . 0038^{n s} x^{2}$	0.74
SPS/NS	71.3	a	71.9	a	72.5	a	73.3	a	72.2	a	72.6	a	$y = 71.03 + 0 . 2713^{n s} x - 0 . 010^{n s} x^{2}$	0.73
Black globe humidity index (BGHI)
SPS/EW	77.2	a	78.8	a	79.5	a	77.4	a	74.0	b	73.4	b	$y = 72.843 + 1 . 1835^{n s} x - 0 . 0612^{n s} x^{2}$	0.66
SPS/NS	74.7	a	76.0	a	76.7	a	77.5	a	77.6	a	77.7	a	$y = 74.437 + 0.3849 * * x - 0.0112 * * x^{2}$	0.98
Enthalpy (H)
SPS/EW	65.7	a	66.0	a	66.4	a	63.3	b	62.4	b	62.5	b	$y = 66.319 - 0 . 1145^{n s} x - 0 . 0053^{n s} x^{2}$	0.78
SPS/NS	67.2	a	67.4	a	67.6	a	67.7	a	67.5	a	67.6	a	$y = 67.148 + 0 . 0737^{n s} x - 0 . 0027^{n s} x^{2}$	0.83
Radiant heat load (RHL)
SPS/EW	580	a	613	a	632	a	607	a	525	b	506	b	$y = - 577.14 + 11 . 336^{n s} x - 0 . 7847^{n s} x^{2}$	0.87
SPS/NS	539	a	569	a	579	a	594	a	657	a	625	a	$y = 530.49 + 8 . 4869^{n s} x - 0 . 156^{n s} 2 x^{2}$	0.83

Systems	Time (h)								Regression	R²
Systems	8		11		14		17		Regression	R²
Air temperature (°C)
SPS	17.4	a	29.2	a	31.8	b	27.7	a	$y = - 51.475 + 12.158 * x - 0.4417 * x^{2}$	0.99
UPS	18.5	a	29.9	a	34.3	a	28.5	a	$y = - 55.811 + 13.091 * x - 0.4778 * x^{2}$	0.99
Air relative humidity (%)
SPS	80.7	a	33.2	a	27.1	a	39.3	a	$y = 339.83 - 45 . 802^{n s} x + 1 . 6583^{n s} x^{2}$	0.98
UPS	69.9	b	29.4	a	21.8	b	30.9	b	$y = 289.69 - 38 . 598^{n s} x + 1 . 3778^{n s} x^{2}$	0.99
Black globe temperature (°C)
SPS	19.6	b	34.3	a	38.2	b	27.8	a	$y = - 82.997 + 18.381 * x - 0.6972 * x^{2}$	0.99
UPS	26.3	a	38.8	a	44.1	a	28.0	a	$y = - 85.228 + 20 . 208^{n s} x - 0 . 794^{n s} 4 x^{2}$	0.95
Wind speed (m s^-1)
SPS	0.11	a	3.05	b	3.65	b	1.20	a	$y = - 21.32 + 3.8721 * x - 0.1497 * x^{2}$	0.99
UPS	0.10	a	6.94	a	6.83	a	2.18	a	$y = - 44.821 + 8.1835 * x - 0.3192 * x^{2}$	0.99
Temperature and humidity index (THI)
SPS	60.9	b	73.5	b	78.0	b	74.0	a	$y = - 13.511 + 12.988 * * x - 0.4611 * * x^{2}$	0.99
UPS	63.8	a	76.1	a	81.3	a	75.9	a	$y = - 14.308 + 13.675 * x - 0.4917 * x^{2}$	0.99
Black globe humidity index (BGHI)
SPS	65.8	b	81.1	b	85.5	b	74.5	a	$y = - 41.914 + 19.281 * x - 0.7306 * x^{2}$	0.99
UPS	73.4	a	86.3	a	92.0	a	74.8	a	$y = - 43.736 + 21 . 233^{n s} x - 0 . 8361^{n s} x^{2}$	0.94
Enthalpy (H)
SPS	53.4	b	67.9	b	73.9	b	68.1	a	$y = - 36.814 + 15.767 * x - 0.5639 x^{2}$	0.99
UPS	59.5	a	73.3	a	80.0	a	70.1	a	$y = - 46.831 + 18 . 931^{n s} x - 0 . 7139^{n s} x^{2}$	0.97
Radiant heat load (RHL)
SPS	436	a	686	b	751	b	469	b	$y = - 1625.6 + 374 . 91^{n s} x - 14 . 778^{n s} x^{2}$	0.98
UPS	494	a	903	a	955	a	441	a	$y = - 2974.8 + 637 . 41^{n s} x - 25 . 639^{n s} x^{2}$	0.98

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[1] Rafael P. de Carvalho - E-mail: rafael.carvalho@ifms.edu.br (Corresponding author)