The Effects of Weather Elements

Endrédi Lajos: Biológiai vizsgálatok, 454. oldal – Nemzeti Tankönyvkiadó, Budapest, 2000

The dependence of net phytomass production of four subassociation of the Salvio Festucetum rupicolae pannonicum (loess-sward) phytocoenosis on weather conditions was studied. The effects of the following climatic conditions: the air temperature, the precipitation and the global radiation on the primary production were estimated with multivariate regression analysis and pathanalysis. The results show a close correlation between the weather elements and the productivity. The global radiation and the temperature were influenced to the highest degree. 49–62% of variation in the total net phytomass production was determined by the climatic factors together.

Vizsgáltuk a Salvio Festucetum rupicolae pannonicum (löszpusztarét vagy löszgyep) növénytársulás négy szubasszociációjának nettó fitomassza produktuma függését az időjárástól. A klimatikus tényezők közül a levegő hőmérséklete, a csapadékmennyiség és a globális sugárzás primer produkcióra gyakorolt hatását többszörös regresszióanalizissel, illetve az ezen alapuló pathanalízissel becsültük. A vizsgálat eredményei szoros korrelációt igazolnak az időjárási elemek és a produktivitás között. A legnagyobb mértékben a globális sugárzás és a hőmérséklet alakulása hatott. A klimatikus faktorok együttesen a teljes nettó fitomassza produktumot 49–62 % közötti arányban határozták meg.

The close relation between the plant productivity and the climatic environmental factors in different types of vegetation on the Earth – concerning particular zones or vegetation formations – is well-known (Bazilevics, Drozdov and Rodin, 1968; Lieth, 1972; Jones, 1984 and the others). However, the broadly affirmable correlations show considerable anomalies in the case of some phytocoenosises, so local valid correlations can only be known with the direct determining of productivity of the given phytocoenosis and with the de facto influential environmental conditions including the weather elements.

The using of mathematical statistical methods is absolutely necessary for the exploration of correlations. The pathanalysis is deemed the most adaptable manner (Godall, 1970; Zólyomi and Précsényi, 1970). However, this method hasn’t been general enough yet in the case of production-biological studies, in Hungary from O’sváth’s (1961) description was first used Zólyomi and Précsényi (1970), Précsényi (1971, 1975) used the method for the analysis of salt pastures and Kovács-Láng and Szabó (1973), Láng (1974) applied it for the analysis of correlation between the primary productivity of the sandy meadow associations and the weather elements.

We applied pathanalysis for demonstrating the correlation between the productivity of loess-sward and the change of the weather elements. We published some information from results of short periods (Endrédi, 1986; 1988; 1989), in this chapter we treat data for a period of 10 years. The summary of the results was published in the Abstracts of The 7^th European Ecological Congress (Endrédi, 1995).

The using of pathanalysis assumes direct measuring in the biocoenosises. We measured the production of natural loess-sward phytocoenosis in a loess-hill called Dunaföldvári Nagyhegy (Fig. 1).

The primary production of the following four subassociations of the Salvio-Festucetum rupicolae pannonicum ZÓLYOMI, 1958 (loess-sward) plant association (Soó, 1964; 1973; 1980) was studied:

The primary net productions were determined with monthly samplings from April to October (in five years there were six yearly samples from early April to early October, and in five years this number was seven from early April to late October, in every year the sampled stands weren’t cut back at the beginning of studies) for determining of the production. The rates of productivity – which were counted from the primary net productions – were used for pathanalysis. The total net production was separated into two parts: underground and above-ground fractions. In the production of above-ground fraction the living (phytobiomass) and the dead plantal parts were measured separately. During the investigational periods we continuously recorded the air temperature, the precipitation and the global radiation. The methods of production-analysis and the measuring of weather conditions can be found in our former publications (Endrédi and Horváth, 1976; 1977; 1979; Endrédi, 1984).

In this chapter we treat data for a period of 10 years from 1974 to 1994. In case of weather factors the +/- difference between two samples, in case of products the productivity of interval between two samples was considered basic data, the numbers of basic data were 65–65 for each variable. The fact, that the weather elements are de facto environmental factors, were proved with multivariate regression analysis, the rates of effect of independent variables were estimated with pathanalysis. The statistical calculations were based on Sváb’s (1973, 1979) publications. We used a computer for the data processing.

We studied – according to our aims – what connection existed between the change of mean temperature, precipitation and global radiation of the observed intervals and the productivity of vegetation. The influences were investigated separately regarding the underground and the above-ground phytomass, and the change of production of above-ground living and dead plantal parts was also considered separately, and naturally the calculations were done considering the changing of the total production too. We accounted the weather elements independent and the values of productivity dependent valuables from the point of view of mathematics.

The exposition of the great number of measuring results and a lot of derived data concerning valuables is an impossible task in this short chapter, so we only show and explicate the results of mathematical statistical processes.

1) The correlation between the weather elements and the productivity was proved with multivariate regression analysis. The Table 1 shows the multiple correlation coefficients between the productivity and the change of climatic elements.

It is observable that in the case of productivity resulting from the total net phytomass the correlation is significant in every subassociation. The Salvio-Festucetum rupicolae angustifoliae stands show the closest correlation. The relation is also close in S.-F. r. stipetosum capillatae stands but it is closer in S.-F. r. andropogonetosum stands. The observed climatic factors have the least effect on productivity in the case of S.-F. r. festucetosum rupicole stands.

Concerning the fractions there is a very close correlation respecting the above-ground phytobiomass, in the case of underground phytomass-productivity the relationship is the weakest.

	Salvio-Festucetum rupicolae pannonicum
Fractions	festucetosum rupicolae	stipetosum capillatae	andropogon-etosum	poëtosum angustifoliae
Above-ground phytomass	0,6460	0,8330^*	0,6502	0,8626^**
Above-ground phytobiomass	0,7150⁺	0,9050^**	0,7831^*	0,8821^**
Above-ground dead parts	0,7757^*	0,5515	0,6525	0,7860^*
Under-ground phytomass	0,5313	0,5800	0,7597^*	0,6057
Total phytomass	0,6990⁺	0,7370⁺	0,7859^*	0,7543^*

2) We also observed the extent of effect of the climatic factors on productivity. To this we had to determine the correlation and path-coefficients among valuables, which were summarized in the Tables 2–5.

	*Productivity*
Weather elements	Above- ground phytomass	Above- ground phytobiomass	Above-ground dead parts	Under-ground phytomass	Total phytomass
correlation coefficients
Temperature	0,4852⁺	0,6483^*	– 0,4556	0,3552	0,4444
Precipitation	– 0,1677	– 0,1817	0,0110	0,0652	– 0,0499
Radiation	0,7417^**	0,8533^***	– 0,2277	0,5440⁺	0,6799^*
path-coefficients
Temperature	– 0,6182	– 0,3774	– 0,9686	– 0,3807	– 0,5263
Precipitation	– 0,2695	– 0,2630	– 0,0821	– 0,0012	– 0,1380
Radiation	1,2789	1,1879	0,5981	0,8672	1,1330

Note: Probability level of significance (P): ⁺ : 10%; ^*: 5%; ^**; 1%; ^***: 0,1%

	*Productivity*
Weather elements	Above- ground phytomass	Above- ground phytobiomass	Above-ground dead parts	Under-ground phytomass	Total phytomass
correlation coefficients
Temperature	0,6144^*	0,7284^**	– 0,3830	0,6702^*	0,7233^**
Precipitation	0,0546	0,2292	– 0,3212	– 0,1618	– 0,0756
Radiation	0,4329	0,6838^*	–0,5675^**	– 0,3812	0,4520
path-coefficients
Temperature	– 0,6182	– 0,6305	0,2496	1,2199	1,2267
Precipitation	– 0,2995	– 0,2651	– 0,2683	– 0,0493	0,0345
Radiation	1,2789	0,1363	– 0,7667	– 0,6516	– 0,5906

	*Productivity*
Weather elements	Above- ground phytomass	Above- ground phytobiomass	Above-ground dead parts	Under-ground phytomass	Total phytomass
correlation coefficients
Temperature	05339⁺	0,6956^**	–0,7743^**	0,5034⁺	0,5618^*
Precipitation	– 0,1310	– 0,0816	– 0,0790	– 0,2677	– 0,2261
Radiation	0,7911^**	0,8674^***	– 0,6542^*	0,5281⁺	– 0,6991
path-coefficients
Temperature	– 0,5791	– 0,1997	– 0,8359	0,0889	– 0,2207
Precipitation	– 0,2307	– 0,1442	– 0,1380	– 0,2837	– 0,2832
Radiation	1,2933	1,0437	0,0616	0,4660	0,8997

Note: Probability level of significance (P): ⁺ : 10%; ^*: 5%; ^**; 1%; ^***: 0,1%

It is apparent that the productivity was determined mostly by the global radiation and the mean temperature, but the precipitation hadn’t a significant effect. Naturally, it doesn’t mean as if the precipitation weren’t an ecological factor (or even in the given cases it was a very important limiting factor), merely the thing is this that the linear effect of the change in precipitation couldn’t be proved mathematically in the observed range of productivity.

Theoretically the value of path-coefficients are in the range between +1 and –1. Nevertheless, there are some values above 1 in the charts. The reason for this may be the very close correlation (p=0,001) between two independent valuables (the mean temperature and the global radiation) (Sváb, 1979).

The direct, paired and total effects of climatic factors on productivity – in separated fractions (in %) – were given in Tables 6–9.

From the results it can be stated unequivocally that the all accounted climatic factors (weather elements) have some direct effect on the productivity. In the case of of three subassociation stands the global radiation bear the most effective direct part in the productivity, but in one subassociation (S.-F. r. andropogonetosum) the temperature was the most important factor. In two subassociations (S.-F. r. poëtosum angustifoliae and S.-F. r. festucetosum rupicolae) the temperature had a slight extent on direct effect. The direct influence of precipitation was minimal in every case. All the indirect effects in pairs were negative, presumably because two climatic factors have derogatory effects on the productivity together (Sváb, 1979).

The direct, paired and total effects of climatic factors on productivity (in %)

Effects		Above-ground phyto- mass	Above-ground phytobio- mass	Above-ground dead parts	Under-ground phyto-mass	Total phyto-mass
Direct	Temperature	15,85	11,95	2,83	15,04	5,45
effects	Precipitation	2,97	5,27	10,42	9,58	5,95
	Radiation	6,37	13,02	30,28	57,20	74,38
Paired	Temperature – Precipitation	– 0,92	– 1,06	–0,73	–1,61	– 0,76
effects	Temperature – Radiation	17,05	21,17	15,70	–49,78	–34,16
	Precipitation – Radiation	0,41	0,78	1,67	–2,21	–1,98
Total climatic effect		41,73	51,13	60,18	28,23	48,87
Other effects		58,27	48,87	39,82	71,77	51,13

The direct, paired and total effects of climatic factors on productivity (in %)

Effects		Above-ground phyto- mass	Above-ground phytobio- mass	Above-ground daed parts	Under-ground phyto-mass	Total phyto-mass
Direct	Temperature	38,21	14,24	93,83	14,50	27,70
effects	Precipitation	7,26	6,92	0,67	0,00	1,90
	Radiation	163,57	141,11	35,78	75,20	128,37
Paired	Temperature – Precipitation	– 2,23	– 1,33	–.1,07	0,00	– 0,97
effects	Temperature – Radiation	–134,18	–76,08	–98,33	–56,04	–101,21
	Precipitation – Radiation	–3,25	–2,94	– 0,46	0,00	– 1,47
Total climatic effect		69,38	81,91	30,42	33,65	54,32
Other effects		30,62	18,09	69,58	66,35	45,68

The direct, paired and total effects of climatic factors on productivity (in %)

Effects		Above-ground phyto- mass	Above-ground phytobio- mass	Above-ground dead parts	Under-ground phyto-mass	Total phyto-mass
Direct	Temperature	87,26	39,75	6,23	148,81	150,48
effects	Precipitation	1,81	7,03	7,20	0,24	0,12
	Radiation	13,41	1,86	58,78	42,46	34,88
Paired	Temperature – Precipitation	– 1,69	– 2,24	0,90	0,81	– 0,57
effects	Temperature – Radiation	–58,05	14,58	–32,48	–134,91	–122,95
	Precipitation – Radiation	– 0,46	0,34	1,94	0,30	– 0,19
Total climatic effect		42,28	61,32	42,57	57,72	61,77
Other effects		57,72	38,68	57,43	42,28	38,23

The direct, paired and total effects of climatic factors on productivity (in %)

Effects		Above-ground phyto- mass	Above-ground phytobio- mass	Above-ground dead parts	Under-ground phyto-mass	Total phyto-mass
Direct	Temperature	33,53	3,99	69,87	0,79	4,87
effects	Precipitation	5,32	2,08	1,90	8,05	8,02
	Radiation	167,27	108,93	0,38	21,72	80,95
Paired	Temperature – Precipitation	– 1,79	– 0,39	–.1,55	0,34	– 0,84
effects	Temperature – Radiation	–127,10	–35,38	– 8,74	7,03	–33,71
	Precipitation – Radiation	–2,81	–1,42	– 0,08	– 1,24	– 2,40
Total climatic effect		74,42	77,81	61,79	36,69	56,90
Other effects		25,58	22,19	38,21	63,31	43,10

According to the analysis, although the productivity of the investigated vegetation stands were impacted significantly by the combined climatic factors, there were slight differences among the stands. The greatest combined effect of the climatic factors was in the stands of Salvio-Festucetum rupicolae andropogonetosum, the degree was about 62%, while the least extent of effect can be seen in the Salvio-Festucetum rupicolae festucetosum rupicolae stands, the rate was only about 49%. In the S.-F. r. poëtosum angustifoliae the rate was about 57%, in the S.-F. r. stipetosum capillatae stands it was about 54%.

On the other hand, there are considerable differences among the fractions. Except for the Salvio-Festucetum rupicolae festucetosum rupicolae stands, in every stand the growing of phytobiomass of the above-ground parts was influenced by the combined climatic effects mostly: the highest rates were 82% in the S.-F. r. stiposetum capillatae, the lowest rates were 51% in the S.-F. r. festucetum rupicolae. We got substantial differences in the changing of productivity of phytomass of underground vegetative parts among the stands concerning the rate of the combined effect of the climatic factors: in the S.-F. r. andropogonetosum stands the rate is almost 58%, while in the S.-F. r. festuvetosum rupicolae it is only 28%; moreover, in the other two subassociations the rates of impact are also low (37 and 34%).

The Figure 2 shows the rates of combined climatic effects on productivity in separated fractions.

A: Above-ground phytomass; B: Above-ground phytobiomass; C: Above-ground dead parts;

Although, there are other important effects (between 38 and 51%), in this chapter – according to our aims – we only dealt with three climatic factors from all possible factors that can have an effect on the primary productivity.

We studied the dependence of net phytomass production on weather conditions in four subassociations (S.-F. r. festucetosum rupicole, S.-F. r. stipetosum capillate, S.-F. r. andropogonetosum, S.-F. r. poëtosum angustifoliae) of Salvio Festucetum rupicolae pannonicum (loess-sward) biocoenosis for a period of 10 years. Monthly samples were taken from April to October including both above-ground and underground parts. During the exploration the values of following weather elements which have an important role in the point of view of productivity, were continuously recorded: the air temperature, the precipitation and the global radiation.

The effects of climatic factors on the primary production were estimated with multivariate regression analysis and pathanalysis. The influences were studied not merely regarding the total net phytomass production but also two fractions separately: the underground and above-ground phytomass productions, and in the production of above-ground fraction, the living (phytobiomass) and the dead plantal parts were also recorded separately. The extent of the effect of the weather elements on the productivity was estimated separately, in pairs and collectively.

The results prove a close correlation between the weather elements and the productivity. The run of global radiation and temperature had an effect to the highest degree, the linear effect of precipitation couldn’t be proved mathematically in the observed range of productivity. The effect of the combined climatic factors on the total net phytomass production was 46–62%: the least rate was in the S.-F. r. festucetum stands, while the greatest rate was in the case of S.-F. r. andropogonetosum stands. There were also considerable differences between the fractions: the combinate effect of climatic factors was the most significant in the case of above-ground phytomass (51–82%), the least extent of effect was found in the underground phytomass (28–58%).

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	*Productivity*
Weather elements	Above- ground phytomass	Above- ground phytobiomass	Above-ground dead parts	Under-ground phytomass	Total phytomass
correlation coefficients
Temperature	0,6007^*	0,6365^*	– 0,6134^*	0,2747	0,5148⁺
Precipitation	0,1576	0,2233	– 0,3375	–0,2479	– 0,1876
Radiation	0,5983^*	0,6650^*	–0,7082^**	0,4126	0,6529^*
path-coefficients
Temperature	0,3981	0,3457	– 0,1681	– 0,3878	– 0,2334
Precipitation	0,1724	0,2295	– 0,3228	– 0,3096	– 0,2439
Radiation	0,2523	0,3608	–0,5503	0,7563	0,8624