Kovács-Láng, Edit

Szabó, Mária

English

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ТНК EFFECT OF ENVIRONMENTAL FACTORS ON THE PHYTOMASS PRODUCTION OF SANDY MEADOWSbyE D I T H  K O V Á C S  - L Á N G  and M Á R I A  S Z A B  6  D epartm en t o f P lan t T axonom y and  Ecology of the E ötvös Loránd U niversity , B ndapes Received on the 304' May 1972The examinations of the authors were begun in 1968 within the IBP, and aimed at acquiring information on the production conditions of natural sandy meadow associations, as well as cultivated stands, further at disclosing the effect of factors influencing production.With this in view, in the years 1968 and 1969, the authors examined the monthly changes of the phytomass in the various ecosystems during the vegetation period, and followed with attention the values of the climatic factors — monthly mean temperature, relative atmospheric humidity, monthly total precipitation, global insolation, as well as soil moisture — of the examined associations. In  their paper ( K o v á c s -  L á n g — S z a b ó ,  1971) they dealt with the production conditions of the examined meadow associations and with the trend of the moisture content of their soils. In the present work — a continuation of the said paper — they strove to throw light upon the role of the examined en­vironmental factors in the production of the sandy meadows by applying mathematical methods.Material and methodsThe examinations took place in Csévharaszt (Hungarian Plain), a region with wooded steppe vegetation of the sandy area between the rivers Danube and Tisza, in meadow associations forming a natural succession series. The initial stage of the succession series is formed by a Brometum tectorum sandy meadow which gradually yields ground to an association of a perennial open sandy meadow: Festueetum vaginatae da- nubiale. The latter one is found in the widest range within the area of the examination. The closing of the grassland cover begins with the association Festueetum sulcatae, which — in places — leads to the formation of closed Festueetum wagneri. The present examinations were centred upon the perennial sandy meadows Festueetum vaginatae and6*Fest acet um war/neri. For comparison, tlie authors determined tlie pro­duction values of rye, cultivated in a near-by field. A detailed descrip­tion of the meadow associations is to be found in earlier papers of the authors ( К ο ν  á c s — L á n g, 1970, K o v á c s -  L á n g  -  Sz  a b ó, 1971, V e r s e g h y  — K o v á c s  — L á n g, 1971). The phy tomass was weighed every month, by taking 11, 20X 20χ  20 cm. monoliths from each of the associations and separating the cryptogamie (moss, lichen) and floral living and non-living parts to be found on the surface of each monolith, as well as the underground parts in it.Simultaneously with sampling, humidity was measured by means of a neutron-scattering moisture-meter in the soil of the examined associa­tions. at depths of 20, 40, 60, 100, 140 and 200 cm. ( K o v á c s  — L á ή g — S z a b 6 , 1971). From among the climatic factors, the values of precipitation were founded on the measurements of the Csévharaszt station, those of temperature and relative atmospheric humidity on the ones of the Monor station, while those of global insolation on the ones of the Pestlőrinc Observatory. The said values can be adapted to the examined area. (As regards the problems of adaptation, see P r é e s é -  n y i, 1971 ).When elaborating (he data, the authors did Calculations for deter­mining the depth of soil in the various associations, of which the change in moisture content correlated most with the change in phvtomass production.The change of production is expressed most expediently by produc­tivity — i. e. the value of production to the time unit (I day) and to the space unit — in this way the values of the examined factors also reflect the extent of the changes ensued between the dates at which the samp­les were taken. So that information can be acquired on the role of the factors, on their weight as compared with one another, as well as on other factors — not examined by them — the authors did path ana­lysis (O s V á t h. 1961, P r é c s é n y i. 1971).Results of the examination'fhe data on the productivity of the overground floral living parts of the meadows selected for assessment are summarized in Table I .In the natural meadows Festucet urn vaginatae and Festucetum wagneri two production maximums are to be observed, in early summer and in autumn.Table II. includes thevaluesof the changes of theexamined environ­mental factors.The preliminary correlation analysis conducted by the authors concerning the relationship between the change in moisture content as measured at various depths and productivity indicates, that at the deeper levels (140 cm.) of the soil of the open sandy meadow — Festu­cetum vaginatae — it is the change in the humidity content, which is,S4 K O V Á C S  — L A N G  — SZ A B ÓTable I.Productivity ol overground living parts ot grassland communities (g 4 dm2/day)P H Y T O M A S S  P R O D U C T IO N  O F SA N D Y  M E A D O W S 8 5F e s tu c e t  u n i v a g in a la e F e s t  ucet и  ni ira у  n e r  i S e c a le t u m  c u l tu mDay of D ay of Day ofsam pling sam pling sam pling190S 1969 1909V. 23.-0 .0 5 0IV. 10.+  0.008IV. 10.+  0.204VI. 21+  0.020V. 19+  .0020V. 19+  0.323VII .  22-  0.027VI. 10+  0.037VI. 10.-0 .4 4 5V il i .  30+  0.10SVII .  22-0 .1 0 0VII .  22-  0.075IX . 12— 0.058Vi l i .  13+  0.044VII I. 13X. 10 X I. Il— 0.034X . 13positively correlated with productivity (correlation coefficient: +0.60). Owing to the desiccating effect of intensive insolation acting on the surface of the soil, the upper levels of same dry up rather rapidly, and thus moisture can he stored but in the deeper levels.In the closing meadow Feslucelum way neri, the water economy of the soil is modified by the shadowing effect of vegetation. The fluctuations of the moisture content of the upper levels are less, and show a positive correlation with the productivity of the phytomass (correlation coef­ficient: + 0.75). Table II I . comprises the results of the analysis of the cor­relation of the examined factors with one another and with the produc­tivity of the natural meadows.The productivity of the Feslucelum vaginulae perennial open sandy meadow shows positive but not close correlation with relative atmospheric humidity (correlation coefficient: +0.46). Λ negative connection of negligible measure appeared with the other factors.In the closing perennial sandy meadow — Feslucelum wagneri — it is the moisture of the soil measured at 40 cm. depth and the global in­solation, which are positively correlated (correlation coefficient: +0,75 and +0,56. With the other ifactors, the connection is not so expressed. Path analysis (Table I V .) gives a nearly similar result regarding the na­tural meadows.Table I I .a) Changes ot weather elements8 6  K O V Á C S  — L A N G  — SZ A B OYear and monti) 1 a b c d1968 V.4-0.133 4-0.766 -0 .1 3 3 +  40.000VI.4-0.010 4-0.354 — 0.096 -  9.300VII .-  0.022 4-0.387 4-0.541 -  66.200V ili .-0 .1 0 6 -  0.900 4-0.290 -  39.200IX .-0 .1 6 1 -1 .1  19 4-0.032 -2 1 .9 0 0X.1969 IV.4-0.251 4-1.741 4-0.129 4-40.900V.-0 .0 1 0 4-1.666 4-0.433 -  20.800VI.4-0.096 -2 .7 0 9 -0 .2 2 5 4-25.500VII .-  0.025 4-0.741 4-0.193 -4 5 .7 0 0VI II.-  0.080 -1 .4 6 6 4-0.066 -2 9 .0 0 0IX.X.-0 .1 4 2 4-0.483 4-0.032 -  36.800Symbols:a =  m onthly  mean tem pera tu re  (C) b =  am ount o f m onthly  precip itation  (mm) c — rela tive hum id ity  (%)cl = sum  of m onthly  global insolation (cal/4 dm 2/day)I t is relative atmospheric humidity and global insolation, which exert the most decided effect on the variability of productivity, the third place is taken by the effect of the other non-examined factors. Ho­wever, in the closing meadow the relative effect of the other factors is substantially smaller than in the open meadow. According to the calcu­lations of the authors, in both associations the changes in the monthly mean temperature, in the monthly total precipitation and in soil hu­midity affect the variability of productivity of the phytomass in a rather slight measure.Table 11 jbb) Changes ot soil moisture content (%)P H Y T O M A S S  P R O D U C T IO N  O F  S A N D Y  M E A D O W S  87Table I I I .Correlation coefficients <r) between the change of phytobiomass «eights an.l the change o!studied factorsl'o r the sym bols a , b , c, d, see Table 2. e =  soil m oisture content.Stúdiód clemente b C1d eFest ucetum vaginatatа +  0.65 -0 .3 1 +  0.45 +  0.13 -0 .2 4b -0 .2 4 +  0.39 +  0.20 -0 .3 0-0 .8 9 - 0 .1 6 +  0.46d +  0.26 -0 .3 2-0 .4 0eF est ucetumStudied elements b C d C uagneri+  0 .H -0 .0 8 +  0.90 +  0.40 +  0.24b +  0.89 -0 .1 4 -0 .8 1 -0 .4 0C -0 .3 4 — 0.57 -  0.26d +  0.55 +  0.56+  0.75eYear and Y ear and Y ear andm onth Festueetum m onth Festucelum m onth Secaletum1968 vaginatae 1969 wagneri 1969 cultumV. IV. IV.+  0.107 -0 .0 2 3 -0 .0 4 1VI.-0 .0 1 9V.-0 .0 1 8V.+  0.007V II.-0 .0 1 3V I.+  0.014VI.+  0.011v i n .+  0.008V II.-0 .0 3 6V II.-0 .0 5 4IX .+  0.017V il i .+  0.028V il i .X. IX .-0 .0 1 3X.Filth coellicients between the phytobiomiiss weight <>( the eeosvstems (n) and the pereentnal rate of the different faetors (h) '8 8  K O V Á C S — L A N G  — S Z A B OFor the sym bols n, b, e, d , e see Table 2 and Table 3.The subsequent summary shows the order of Die intensity of the eitects of the examined factors, relying on the path coefficients:. . . a b o d e  othertestaceiam vaginalae 4 5 ] о ·5Festucetum way neri <ί 5 v ] 4(The meaning of a, b, c, d and e see in Tables 2 and 3).„ J1! ccrtain cases. e. g. with Fest uret um vaginalae, the correlation coefficient between the changes of global insolation and productivity is negative (-0.32), while, as to be demonstrated by path analysis, -dohai insolation exerts a marked direct influence on productivity (path ooefi- fioient: +0.926G). The same is to be observed with relative atmospheric humidity and productivity in the Fest acetum wagneri meadow the value of the correlation coefficient is: -  0.26, that of the path coefficient· -f 1.4651.The reason for these phenomenons is that, besides the direct effect also the indirect -  mutual -  effects come to be expressed and the latter can exert an intensive modifying influence.Thus e. g„ in F est acetum vaginalae, the correlation between global insolation and the productivity of the green phvtomass is- -  0 32 The correlation can be resolved to the following components:direct effect of global insolation с>2<>(»indirect effect through soil humidity _ 0 ' jn l jeffect through relative atmospheric humidity _ ]  o]q3effect through the mothly total precipitation -0.082!)effect through the monthly mean temperature —0.0524altogether —0.3201Ecosystem Direct effects I 1Indirect 1 Othera b - 1 -1 ea) Fvslure-turn vagi-n a ta e ......... -  0.1104 -0 .2 1 2 0 +  1.1352 +  0.9200 — 0.3SS-1Festucet um *I 0.7284wagneri . . . -  1.3555 -1 .3 1 0 0 +  1.4051 +  2.1710 -  0.129Г) 0.2392li) Festucetumvaginalae . 1.35 4.51 128. SO 85.85 15.12 -  1 38.40' 52,77Festucetumwagneri . . . 1 S3.73 173.13 214.05 471.53 18S.5(5 -  950.53 5.72The examination of the cultivated stand — rye field — Secalelum cultum — gives a different result.The productivity of the overground floral living parts (Table 1) shows a maximum in early summer (May and June), and the vegetation period of this association ends with the harvest in July.As to he seen from the calculations of the correlation of the examined factors with one another and with productivity (Table V.),  the produc­tivity of the overground living substance shows a marked positive corre­lation with the changes of relative athmospherie humidity and monthly total precipitation (correlation coefficients: +0.81 and +Ò.70). With the other factors, the correlation is negligible.О оTable V.Correlation cocllicients (r) between the change ol phytobiomass weight anti the change olStudie«! factores in arye-lielclP H Y T O M A S S  P R O D U C T IO N  O F  S A N D Y  M E A D O W S «<»For the sym bols a, b, e, d , e see Table 2 and Table 3.The result of path analysis.(Table V I .) shows that, differently from the natural meadows, the greatest effect on the productivity of rye is exerted by the changes of temperature. 'I’he changes of the values of monthly total precipitation and soil humidity influence the variability of the productivity of the phytomass in a nearly identical measure. In contrast with the natural meadows, the direct effect of the changes in global insolation and atmospheric humidity is rather slight.Among the examined environmental factors, soil humidity takes a special place since, besides the climatic factors, it depends on quite a series of other soil factors and on vegetation.For a trial, the authors carried out path analysis taking only the climatic factors into consideration and leaving out soil humidity. Hardly any change in the values of the other factors resulted from the omission of the moisture of the soil in the natural meadows, where its effect on productivity was small (it gave a low path coefficient). However, in the rye field, where the changes of soil humidity originally showed a marked influence on productivity, calculations brought a different result when this factor was left out. The intensity of the effects of the examined factors changed both absolute value and in order of succession (cf. Tables VI. and VH.).Studied elements b i c d Rye fielda +  0.04 1 -0 .2 8 +  0.7(> -  0.48 +  0.07b +  0.S9 -0 .2 0 -0 .4 7 +  0.70C -0 .5 0 -0 .1 8 +  0.81d +  0.23 +  0.08e -0 .2 0Table V I .Path coeflicients between the phytobiomass weight ot the rye-lield (a) ami the percentualrate ot the ditterent taetors (b)9 0  K O V Á C S  — L A N G  — SZ A B OTable V I I .Hank ot correlation eoettieientsFor the sym bols a, b, c, d , e see Table 2 and  Table 3.SummaryFrom among the environmental factors, the authors examined the effect of the changes of monthly mean temperature, global insolation, relati­ve atmospheric humidity, monthly total precipitation and the soil mois­ture content upon the productivity of the overground living phytomass of sandy meadows Feslucetum vaginulae, Festucetum wagneri, as well as of a rye field. The connections between the examined factors and pro­ductivity were approximated by means of correlation analysis and path analysis. The greatest direct effect on the productivity of the natural meadows is exerted in the first place by changes of relative atmospheric humidity and global insolation and, on that of the rve field, by the chan­ges in temperature.a ь « d e otherW ith soil m oisture 1 3 5 6 2 4W ithout soil mois-t u r e ...................... 4 5 1 2 — 3Rye fieldDirect effectsIndirecta b о d 1 eW ith «) +  1.5653 +  1.2469 -  0.3355 -  1.2894 +  1.3752 0.8166soilm oisture b) 245.01 155.47 11.25 166.25 188.56 -7 3 3 .2 3 66.69W ithoutsoil") -0 .1 1 9 3 -  1.5721 -j- 2.97(H) +  1.4280 — 0.8184m oisture <>) 1.42 247.14 886.01 203.91 — -  1310.51 72.03R EFE R E N C E SK o v a  c .s - L á n g, E . 1970. F ractional hum us investigation of soils under sward com ­m unities (Festucetum  vag inatae danubiale, Festucetum  wagneri) growing on sandy sites. Annales Univ. Sci. 12: 163 — 170.К  о V á c s - b  á n  g , E. — S z a b  ό, M. 1971. Changes o f soil hum id ity  and  its  corre­lation to  phytom ass production in sandy  meadow associations. Annules U niv. Sci. 13: 115 -1 2 6 .O s v á t h ,  .Г. 1961. összefüggések kísérleti m egállapítása. (P ath , analízis). (E xperim ental establishm ent o f connections. — P ath .analysis) M TA A grártud. Oszt. Köziem. 19: 121 -2H 5.P r é e s é n y  i. I. 1971. R elationship  am ong the d ry  m a tte r  production o f n a tu ra l p lan t com m unities and  w eather elem ents. Acta Climat. (Szeged) 10: 69 — 75.P r é c s é n y i ,  I. 1971. Terresztris növényi produkció-tanulm ányok néhány módszer- tan i kérdése. (Some methodological quest ions of st udies on the prod uction of te rre stri­al p lants. (Rot. Köziem. 54: 167 — 173.P r é c s é n y i ,  I. 1969. Analysis o f the prim ary production (phyto-biom ass) in an A rtem isio-Festucetum  pseudovinae. A cta Bot. H ung. 15: 309 — 325.S v á b ,  J .  1967. B iom etriai módszerek a mezőgazdasági k u ta tásb an . (Biom etrical m e­thods in agricultural research.) Mezőgazdasági K iadó, B udapest.V e r s e g h y ,  К.  -  K o v á c s - L á i v ' g ,  E. 1971. Investigations on production o f g rassland com m unities o f sandy  soil in the IB P  area n ear C sévharaszt (H ungary). Production  of lichens. Acta Biol. Acad. H ung. 22: 293 — 311.Z ól у  о m i. В. — P r é c s é n y i ,  I. 1970. The production of the undergrow th and forest step]** meadow in th e  forest at Ű jszentm argita. A cta B ot. H ung. 16: 427 — 444.P H Y T O M A S S  P R O D U C T IO N  O F  SA N D Y  M E A D O W S  9 |

The effect of environmental factors on the phytomass production of sandy meadows

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The effect of environmental factors on the phytomass production of sandy meadows

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