Seasonal variation in productivity in semi-natural grasslands

Figures & data

Table I. Location, annual precipitation, mean annual temperature, soil type, and readily (RAW) and weakly (WAW) plant available water at four study sites.

Location	Lat (N)	Long (E)	Altitude (m)	Precipitation (mm)	Temperature (°C)	Soil^a	RAW^b (mm)	WAW^c (mm)
Orkdal 1	63° 15′	9° 50′	50	965	3.8	scl	89.7	34.2
Orkdal 2	63° 16′	9° 50′	90	965	3.8	scl	83.8	30.9
Gaular 1	61° 22′	5° 49′	300	2022	5.4	sl	65.8	84.7
Gaular 2	61° 23′	5° 49′	300	2022	5.4	sl	62.6	68.3
^ascl=silty clay loam, sl=sandy loam.
^bRAW, water stored at the tension level 0.01 to 0.1 MPa in soil layers above 30 cm.
^cWAW, water stored at the tension level 0.1 to 1.5 MPa in soil layers above 30 cm.

Figure 1. Simulated DM yield plotted against measured values for each year at each site (Orkdal and Gaular). The RMSE is the root mean square error of estimation, and RMSEn is the normalised RMSE, calculated as RMSE divided by the mean observation.

Table II. Statistics on the deviation between measured and simulated DM yield of permanent grassland as affected by cover of herbs (H) and grasses (G) in spring. RMSE is the root mean square error of estimation, and Mea-sim is the measured minus the simulated DM yield.

	RMSE deviation			Mea-sim deviation
	Est.^a	s.e.^b	P	Est.^a	s.e.^b	P
H	−0.16	0.05	0.0018	−0.02	0.0098	0.018
G	−0.20	0.05	0.0006	−0.02	0.013	n.s.
H×G	0.0001	0.00003	0.0024
^aEst. is the estimated value in the proc GLM procedure.
^bs.e. is the standard error of the estimate.

Figure 2. a) Estimated maximum relative growth rate, R _s , of abandoned grasslands as related to six temperature sum intervals, and b) DM production for each year at each study site during the growing season as related to temperature sum.

Table III. Summary statistics of model fit to data for six temperature sum (^oCd) intervals during the growing season over two study sites and four years.

Temp. sum	n ^a	Mean obs.	RMSE^b	RMSEn^c	r ^2
0–500	31	149.162	72.1786	0.4839	0.23
501–700	27	148.897	70.0237	0.4703	0.20
701–900	25	123.33	56.9203	0.4615	0.43
901–1100	27	69.733	56.9203	0.7341	0.08
1101–1500	42	45.137	22.6476	0.5018	0.58
>1500^d	11	41.042	16.7476	0.4081	0.48
^a n, number of paired data points.
^bRMSE, root mean square error of estimation.
^cRMSEn, normalized RMSE, calculated as RMSE divided by the mean observation.
^dOnly fields with registrations higher than 1500^oCd.

Table IV. Relative effect of weather on plant growth expressed as the growth index (GI). The GI is a function of the radiation index (RI), the temperature index (TI), and the drought stress index (WI). Mean and standard deviation of GI, RI, TI, and WI during the temperature sum intervals (^oCd) over the two study sites Orkdal and Gaular and during four years.

Temp. sum	GI ^a	RI ^a	TI ^a	WI ^a
0–500	0.35±0.27	0.71±0.20	0.46±0.30	0.999±0.02
501–700	0.63±0.21	0.74±0.18	0.86±0.16	0.987±0.008
701–900	0.62±0.17	0.71±0.16	0.86±0.11	1.000±0.05
901–1100	0.66±0.19	0.72±0.17	0.90±0.08	1.000±0.0
1101–1500	0.56±0.21	0.72±0.20	0.86±0.13	0.993±0.03
>1500^b	0.56±0.20	0.62±0.19	0.91±0.13	0.995±0.02
^aThe numbers are dimensionless and normalized.
^bOnly fields with registrations higher than 1500^oCd.

Table V. Seasonal variation in estimated numbers of heifers of 350 kg grazing a rotational system with four sub-units (SU1–SU4) of 1 ha, on the basis of simulated DM production at four years in Orkdal and two years in Gaular.

	Start of growth	20.05–29.05	30.05–08.06	09.06–18.06	19.06–28.06	29.06–08.07	09.07–18.07	19.07–28.07	29.07–07.08
		SU1	SU2	SU3	SU4	SU1	SU2	SU3	SU4
Orkdal 1999	12.04	18	26	35	41	29	26	21	15
Orkdal 2000	14.04	25	30	35	40	20	17	16	13
Orkdal 2001	27.04	12	18	25	34	30	28	25	17
Orkdal 2002	6.04	28	37	41	43	25	19	17	17
Gaular 2001	11.05	11	18	28	36	33	32	27	20
Gaular 2002	11.05	18	31	38	43	32	27	22	17