Different Nutrient Use Strategies of Expansive Grasses Calamagrostis

Biologia 67/4: 673—680, 2012 Section Botany DOI: 10.2478/s11756-012-0050-9

Diﬀerent nutrient use strategies of expansive grasses Calamagrostis epigejos and Arrhenatherum elatius

Petr Holub1*, Ivan Tůma2, Jaroslav Záhora2 &KarelFiala3

1Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic; e-mail: [email protected] 2Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrition, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1,CZ-61300 Brno, Czech Republic 3Department of Vegetation Ecology, Institute of Botany, Academy of Sciences of the Czech Republic, Lidická 25, CZ-60200 Brno, Czech Republic

Abstract: Enhanced nitrogen (N) levels accelerate expansion of Calamagrostis epigejos and Arrhenatherum elatius,highly aggressive expanders displacing original dry acidophilous grassland vegetation in the Podyjí National Park (Czech Repub- lic). We compared the capability of Calamagrostis and Arrhenatherum under control and N enhanced treatments to (i) accumulate N and phosphorus (P) in plant tissues, (ii) remove N and P from above-ground biomass during senescence and (iii) release N and P from plant material during decomposition of fresh formed litter. In control treatment, significantly higher amounts of total biomass and fresh aboveground litter were observed in Calamagrostis than in Arrhenatherum. Contrariwise, nutrient concentrations were significantly higher (11.6–14.3 mg N g−1 and 2.3 mg P g−1)inArrhenatherum peak aboveground biomass than in Calamagrostis (8.4–10.3 mg N g−1 and 1.6–1.7 mg P g−1). Substantial differences between species were found in resorption of nutrients, mainly P, at the ends of growing seasons. While P concentrations in Arrhenatherum fresh litter were twice and three times higher (1.6–2.5 mg P g−1)thaninCalamagrostis (0.7–0.8 mg Pg−1), N concentrations were nearly doubled in Arrhenatherum (13.1–15.6 mg N g−1)incomparisonwithCalamagrostis (7.4–8.7 mg N g−1). Thus, the nutrients (N and mainly P) were retranslocated from the aboveground biomass of Calama- grostis probably more effectively in comparison with Arrhenatherum at the end of the growing season. On the other hand, Arrhenatherum litter was decomposed faster and consequently nutrient release (mainly N and P) was higher in comparison with Calamagrostis which pointed to different growth and nutrient use strategies of studied grass species. Key words: competition; decomposition; dry grassland; fertilization; N:P ratio; tissue nutrient concentration

Introduction lic). Elevated nutrient levels accelerate the expansions of tall grasses Calamagrostis epigejos (L.) Roth and Ar- Atmospheric input may substantially affect biogeo- rhenatherum elatius (L.) P.Beauv. in this locality (Fiala chemical cycling, especially in areas subjected to high et al. 2004). C. epigejos, a rhizomatous perennial grass, concentrations of air pollutants. One of the major often tolerates dry sites with a very low content of or- threats to the structure and functioning of ecosystems ganic matter in the soil and low to very low contents are the high levels of air-borne nitrogen (N) pollution of N (Rebele & Lehmann 2001). However, its growth (Bobbink & Roelofs 1995; Bobbink et al. 1998). Al- is enhanced under moist and nutrient rich (especially though some improvements have been made with re- N) conditions (Brünn 1999). A. elatius,atuftsform- spect to the reduction of the amount of pollutants in ing perennial grass, is often found on well-aerated soils Central Europe (Květ 1993; Fanta 1997), acid deposi- of high to moderate fertility (Pfitzenmeyer 1962). Both tion still occurs and current N loads can exceed the mentioned grasses represent plant species of global im- critical loads of plant nutrition in some regions (e.g., portance due to their aggressive colonization of various Eugster et al. 1998; Balestrini et al. 2000; Hůnová ecosystems in Europe and North America (ten Harkel et al. 2004). Bobbink & Roelofs (1995) assessed 7–15 & van der Meulen 1996; Rebele 2000; Wilson & Clark kg N ha−1 per year as N critical load to species-rich 2001; Fiala et al. 2003; Süss et al. 2004). The conversion acid grasslands. Fabšičová et al. (2003) reported higher of native vegetation to an expansive species following capture of mineral N through interception from dewfall eutrophication (e.g., Bobbink & Willems 1988; Aerts (9–18 kg N ha−1) in dry acidophilous grassland in the 1989; Bobbink et al. 1998) suggests that the expander Podyjí National Park (South Moravia, Czech Repub- can take up more nutrients than the displaced resident

* Corresponding author

c 2012 Institute of Botany, Slovak Academy of Sciences 674 P. Holub et al.

Table 1. Mean values of pH, contents of total C and N (%), P, Ca, Mg (mg g−1) and C:N ratio in soils of Calamagrostis epigejos and Arrhenatherum elatius stands in October 2002.

Stands pH (H2O) pH (KCl) C N P Ca Mg C:N

C. epigejos 6.9 6.6 14.7 0.52 0.32 3.7 0.45 28 A. elatius 5.6 4.9 12.7 0.43 0.12 1.5 0.21 30

species. Species replacement during succession can also ground parts of stands (in July) in the 2002 and 2003 grow- have major effects on the N cycle according to van der ing seasons. Samples of aboveground biomass for estimation Krift et al. (2001). They stressed that differences in N of fresh aboveground litter production (FAL) were collected mineralization and nitrification were not simply a func- at the end of the growing seasons (in November). Above- × tion of the net plant biomass production but probably ground biomass was taken from five 20 40 cm quadrates in all control and N fertilized sub-plots. In the second year also of differences in biomass turnover and litter decom- of the experiment, biomass samples were taken from the posability. Rees et al. (2005) reported that N addition different place than in the first year. Collected aboveground to grasses adapted to high soil fertility doubled rhizode- biomass was separated to living and dead plant parts of the position of carbonaceous substances, whereas low soil dominant species. At the end of the growing season, simul- fertility grass species (e.g., Festuca ovina)showedno taneous to sampling the aboveground biomass, five below- response. These changes in the rhizodeposition can ac- ground samples were taken in the harvested plots with a celerate microbial activities, biomass turnover and en- root sampler (diameter 9-cm) to the depth of 15 cm, be- courage even more expansive species. cause roots were not able to penetrate deeper. The total The main objectives of this study was to compare belowground biomass (TBB) was sorted into rhizomes and roots. Aboveground and belowground plant material was the capability of C. epigejos and A. elatius to (i) ac- dried for at least 48 h at 60 ◦C prior to weighing. Collected cumulate nutrients (N and P) in plant tissues, (ii) ef- plant samples were pulverized before analysis. The plant- ficiently remove N and P from aboveground biomass biomass analyses of N and P were performed from an ex- during senescence (nutrient resorption) and (iii) release tract obtained by wet combustion of dried plant material, N and P from plant material during decomposition of N by micro-Kjeldahl technique, P colorimetrically using the freshformedlitter. ammonium vanadate method. At the end of the growing season, representative soil samples from the top 15 cm were taken using a special soil Material and methods sampler for taking undisturbed soil samples. Four soil sub- Study site samples were randomly collected per each sampling plot. Our studies were carried out in the Podyjí National Park Each mixed sample was placed in a plastic bag in the field ◦ near the town of Znojmo (Czech Republic). The study site and kept cool at 4 C until processed in the laboratory. Soil is a dry grassland located near the village Havraníky (48◦49 samples taken from each plot were united as one composite N, 16◦01 E; 320 m a.s.l.) with nutrient-poor shallow soils sample and analysed. Soil characteristics were estimated on of Ranker type (Sedláková & Chytrý 1999). The shallow 2-mm fraction and included pH (in H2O and KCl). Total soils are often called A/C soils, as the topsoil or A horizon C content was determined according to the Kononova and is immediately over a C horizon (unaltered parent mate- Belcikova method, adapted from Novak. Calcium (Ca) and rial on the granitic bedrock). Basic soil characteristics are magnesium (Mg) contents were determined by the method presented in Table 1. The studied locality was character- according to Mehlich II and using GBC933 atomic absorp- ized by annual mean air temperature 9.0 ◦C and 600 mm tion spectrometer. Content of P was determined photo- (2002) and 322 mm (2003) of sum of precipitation during metricaly as a molybdate-phosphate-complex and total N growing season. A great part of the area is covered with content by distillation after mineralization (Kjeldahl tech- dry acidophilous short grass vegetation represented by the nique). plant community Potentillo arenariae-Agrostietum vinealis (Kučera & Šumberová 2010). The great part of original Estimation of decomposition and element release short grass vegetation has been already replaced by nearly The amount of decomposed plant biomass was assessed by monospecific stands of tall grasses Calamagrostis epigejos the mesh-bag method (Tesařová 1993). In each experimental and Arrhenatherum elatius (hereafter referred to as Calam- plot one nylon mesh-bag containing fresh aboveground litter agrostis and Arrhenatherum). Studied stands were not reg- (6 g of dry weight) of corresponding grass species was placed ularly mown before establishment of the experiment. Ten horizontally on soil surface (6 replications for species and permanent plots 6.0 × 2.0 m were laid out in five stands treatment). The size of mesh-bags was 20 × 10 cm (mesh with the dominant species Calamagrostis andinfivestands size 1.5 mm). After the annual exposure (November 26, 2003–October 20, 2004), the samples were cleared of soil par- with the dominant species Arrhenatherum.Ineachplot,3.0 ◦ × 2.0 m sub-plot was fertilized with ammonium nitrate so- ticles by rinsing with water, dried at 60 C in the laboratory, lution (50 kg of N ha−1)infivedosesineachofthetwo and the decrease in dry mass of original sample of litter was growing seasons 2002 and 2003. Permanent plots were cho- assessed. The litter decomposition rate (LDR)wascalcu- lated according to formula: LDR =(lnW0 −ln W1)/(t1 −t0) sen in monospecific stands where co-occuring species were −1 −1 rare. (in mg g day ), where W0 and W1 is the dry mass of litter at the beginning and at the end of the exposure and Vegetation and soil analyses t1 − t0 is the number of days of the exposure (Wiegert & The peak aboveground biomass (PAB) of both studied Ewans 1964). Analyses of N and P both in biomass and un- species was assessed in the maximal development of above- decomposed plant litter, were made by standard methods Different nutrient use strategies of expansive grasses 675

Fig. 1. Aboveground and belowground biomass of Calamagrostis epigejos and Arrhenatherum elatius under control and N fertilized (+N) treatments in two years 2002–2003. * in column indicates greater total biomass at P < 0.05 in comparison to respective column of the other species; other parameters are not signiﬁcant. Columns represent means and bars show SD.

(see previous chap.). On the basis of litter amount estimated (Pyšek et al. 1995). Intensive lateral expansion is also at the start and at the end of exposure and of actual content associated with high competitive ability (Grime et al. of minerals in both original and exposed litter, the release 1988). In our study, there were no significant differ- and/or accumulation of minerals during decomposition were −2 ences in TBB between Calamagrostis (1,094 in 2002 calculated in g m . and 685 g m−2 in 2003) and Arrhenatherum (864 and 652 g m−2, respectively). Nevertheless, both expan- Statistical analyses sive grasses formed more belowground biomass, partic- The data were evaluated by an analysis of variance, us- ularly rhizomes, than the original dry vegetation (759 ing the statistical package STATISTICA 9. A t-test was −2 performed to compare mean differences between species in and 484 g m , respectively). Prach & Pyšek (1999) control and N fertilized treatments (*P < 0.05; **P < 0.01; placed Calamagrostis epigejos among highly competi- ***P < 0.001). In addition, two-way ANOVA was used to tive species which combine two species traits: produce test the effect of plant species and N fertilization, as in- a large number of easily dispersed seeds and are able to dependent variables, on the biomass, nutrient and decom- rapidly spread vegetatively. In addition, high produc- position parameters, as dependent variables. F-value and tion of C. epigejos aboveground biomass decreases the resulting P level (*P < 0.05; **P < 0.01; ***P < 0.001) penetration of solar radiation into meadow stands and were determined. a thick layer of slowly decomposing litter significantly deteriorates the radiation and temperature conditions Results and discussion for the growth of other plant species (Sedláková & Fiala 2001). Significantly higher values of FAL were observed Biomass production in Calamagrostis (699 in 2002 and 533 g m−2 in 2003) in In comparison with Arrhenatherum, whose total bio- comparison with Arrhenatherum (434 and 284 g m−2, mass (PAB + TBB) was 1,227 (in 2002) and 990 g m−2 respectively) at the end of the growing seasons. (in 2003), Calamagrostis biomass reached higher values Positive effect of N fertilization on the biomass was 1,529 and 1,184 g m−2 in both studied years, however generally reported for grasses (e.g., Tůma et al. 2005; significant only in 2002 (Fig. 1). No significant differ- van den Berg et al. 2005; Liancourt et al. 2009; Fi- ences in PAB were found between Calamagrostis (435 in ala et al. 2011). The biomass production is primarily 2002 and 499 g m−2 in 2003) and Arrhenatherum (364 enhanced by the addition of a limiting nutrient, while and 338 g m−2, respectively). However, both expan- the addition of other (nonlimiting) nutrients has lit- sive tall grasses produced more aboveground biomass tle or no effect on biomass production (Vitousek & than the original dry acidophilous grassland with dom- Howarth 1991). In our study, no significant effect of inant Festuca ovina,whosePAB ranged from 175 to enhanced N on both PAB and TBB were found in 310 g m−2 in both studied years (Holub & Záhora Calamagrostis and Arrhenatherum. It indicates a po- 2008). Species dominating in succession exhibit certain tential P limitation or rather co-limitation by two or traits (C-strategy, high stature, high demand for nu- more nutrients in this site. On the other hand, Brünn trients and moisture) which are similar to those pos- (1999) pointed at a relatively smaller biomass incre- sessed by invaders successful in semi-natural habitats ment of Calamagrostis epigejos for dry sites after N 676 P. Holub et al.

Table 2. Mean values ± standard deviation of N, P concentrations (mg g−1) and shoot N/P ratio (mg mg−1) in peak aboveground biomass (PAB) and in fresh aboveground litter (FAL)ofCalamagrostis epigejos and Arrhenatherum elatius under control and N fertilized treatments in two years 2002–2003. Diff in % = Percentage differences shows a higher (+) or a lower (–) value of selected parameter in A. elatius stands in comparison with C. epigejos stands. t-test for differences between species and results of two-way ANOVA analysis (*P < 0.05, **P < 0.01, ***P < 0.001); n =6.

control N fertilized

2002 C. epigejos A. elatius Diﬀ. (%) C. epigejos A. elatius Diﬀ. (%)

[N] PAB 8.4 ± 0.5 11.6 ± 0.8 +38 *** 14.6 ± 0.8 15.4 ± 1.4 +5 [P] PAB 1.7 ± 0.1 2.3 ± 0.2 +35 *** 2.3 ± 0.2 2.2 ± 0.1 –4 N/P ratio 5.7 ± 0.3 5.0 ± 0.6 –12 * 6.9 ± 0.5 7.0 ± 0.5 +1 [N] FAL 8.7 ± 1.0 13.1 ± 1.0 +51 *** 12.1 ± 1.1 15.4 ± 1.5 +27 ** [P] FAL 0.8 ± 0.1 1.6 ± 0.3 +100 *** 1.4 ± 0.1 1.8 ± 0.2 +29 ** N/P ratio 10.0 ± 0.4 7.9 ± 1.0 –21 ** 8.1 ± 0.7 8.8 ± 0.9 +9

two-way ANOVA (F-test) Eﬀect [N] PAB [P]PAB N/P ratio [N] FAL [P] FAL N/P ratio

Species (S) 24.1 *** 15.3 ** 1.5 72.8 *** 51.0 *** 3.7 Nitrogen (N) 145.2 *** 8.2 * 53.9 *** 40.8 *** 17.3 *** 1.9 S x N 8.7 ** 22.0 *** 3.5 2.4 4.1 14.2 **

control N fertilized

2003 C. epigejos A. elatius Diﬀ. (%) C. epigejos A. elatius Diﬀ. (%)

[N] PAB 10.3 ± 0.5 14.3 ± 1.0 +39 *** 12.8 ± 1.0 17.3 ± 1.7 +35 ** [P] PAB 1.6 ± 0.2 2.3 ± 0.2 +44 ** 1.9 ± 0.1 2.7 ± 0.4 +42 ** N/P ratio 7.0 ± 0.5 6.4 ± 0.7 –9 7.2 ± 0.3 6.7 ± 0.6 –7 [N] FAL 7.4 ± 0.8 15.6 ± 1.2 +111 *** 11.9 ± 0.4 20.5 ± 1.4 +72 *** [P] FAL 0.7 ± 0.1 2.5 ± 0.2 +257 *** 1.0 ± 0.1 2.0 ± 0.1 +100 *** N/P ratio 10.6 ± 0.8 6.0 ± 0.1 –43 *** 11.4 ± 0.4 8.3 ± 0.1 –27 ***

two-way ANOVA (F-test) Eﬀect [N] PAB [P] PAB N/P ratio [N] FAL [P] FAL N/P ratio

Species (S) 71.8 *** 43.4 *** 5.3 * 325.1 *** 568.3 *** 362.8 *** Nitrogen (N) 30.7 *** 10.2 ** 1.4 102.0 *** 3.6 59.4 *** S x N 0.3 0.1 0.1 0.2 59.6 *** 13.3 **

fertilization (50 kg N ha−1 year−1), although doses of nificant difference between species in shoot N content 200 kg N ha−1 year−1 resulted in a marked increase of (in g m−2). Also P concentrations in PAB were higher total biomass (Brünn 1999). In addition, Tůma et al. in Arrhenatherum (by 35% in 2002 and 44% in 2003) (2005) found a significant effect of N fertilization on the than in Calamagrostis (Table 2). Thus, shoot P content competitive success of both Arrhenatherum elatius and was greater in Arrhenatherum (0.84 in 2002 and 0.75 Calamagrostis epigejos. At the end of their pot experi- gPm−2 in 2003) than in Calamagrostis (0.64 and 0.66 ment, Festuca ovina almost completely disappeared in gPm−2, respectively). According to the “resource ra- mixtures with both expansive grasses in fertilized treat- tio model” (Tilman 1982, 1997), which proposes that ment (Tůma et al. 2005). the concentration of a nutrient in plant biomass indicates the competitive ability of a species for this nu- Nutrient concentrations trient, since strong competitors are assumed to have a Significant differences between Calamagrostis and Ar- low concentration of decisive nutrients, Calamagrostis rhenatherum in nutrient parameters measured in PAB seems to be a stronger competitor for N and mainly P and FAL are shown in Table 2. The factorial ANOVA than Arrhenatherum. of data from all treatments showed that concentrations Substantial differences between species were also of N and P in PAB and FAL were significantly affected found in resorption of nutrients, mainly P, from senes- by both species and fertilization. However, interactions cent aboveground biomass at the end of the growing of these factors were mostly not significant. N concen- seasons. According to Aerts & Chapin (2000), the abil- trations in PAB were significantly higher in Arrhen- ity of plants to recycle N and P differs: only 50–60% of atherum PAB (by 38% in 2002 and 39% in 2003) than N, but as much as 80–90% of P can be resorbed from in Calamagrostis. Also Kao et al. (2003) found that the aboveground biomass. In the present study, FAL of Calamagrostis canadensis showed low values for above- Arrhenatherum remains partly green till the end of the ground N and P in comparison with other species. How- growing season, because of different growth strategy in ever, due to the variability of PAB,therewasnosig- comparison with Calamagrostis. Skládanka et al. (2010) Different nutrient use strategies of expansive grasses 677

Table 3. Mean values ± standard deviation of litter decomposition rate (LDR), percentage amount of decomposed biomass, and litter production (FAL)inCalamagrostis epigejos and Arrhenatherum elatius stands under control and N fertilized treatments after one year incubation in 2003. Diff in % = Percentage differences shows a higher (+) or a lower (–) value of selected parameter in A. elatius stands in comparison with C. epigejos stands. t-test for differences between species and and results of two-way ANOVA analysis (*P < 0.05, **P < 0.01, ***P < 0.001); n =6.

control N fertilized

2002 C. epigejos A. elatius Diﬀ. (%) C. epigejos A. elatius Diﬀ. (%)

LDR (mg g−1 day−1)1.61± 0.17 2.71 ± 0.35 +68 *** 1.84 ± 0.25 2.84 ± 0.21 +54 *** Decomposed (%) 41 ± 3.27 59 ± 5.05 +44 *** 45 ± 4.41 61 ± 2.74 +36 *** FAL (g m−2) 533 ± 76 284 ± 43 –47 *** 542 ± 58 286 ± 45 –47 ***

two-way ANOVA (F-test) Eﬀect LDR Decomposed (%) FAL

Species (S) 86.4 *** 87.2 *** 15.7 ** Nitrogen (N) 2.6 3.1 0.01 S x N 0.2 0.5 1.2

also confirmed that Arrhenatherum elatius retained suf- in Calamagrostis, while there was no positive effect of ficient quality not only during the drier and warmer enhanced N on P concentration in Arrhenatherum in end of the growing season but revealed itself as a high- both studied years (Table 2). Shoot N/P ratio in PAB quality species also in the stands at higher total pre- increased in both Calamagrostis and Arrhenatherum cipitation amounts. In comparison with concentrations as response to N fertilization, but significantly only in in PAB, P concentrations in senescent FAL of Calama- 2002. grostis were reduced by 53% in 2002 and 56% in 2003, while P concentrations in Arrhenatherum decreased Decomposition and element release only by 30% in 2002 and even increased at the end Decomposition of plant litter varies in a very broad of 2003. Consequently, P concentrations in FAL were range, especially due to the character of decompos- twice (2002) and more than three times (2003) higher ing plant tissues. The rates of microbial decomposi- in Arrhenatherum than in Calamagrostis at the end of tion of plant substrates were highly correlated with the growing seasons (Table 2). It indicates better ability their P or N concentration (Day 1982; Emmer 1997). of Calamagrostis recycle P from above-ground biomass A significantly (F = 43.9; P < 0.001) lower amount of in comparison with Arrhenatherum. In addition, N con- dry mass of litter (41% on the average) was decom- centrations in Arrhenatherum reached higher values in posed in Calamagrostis, whereas 59% of dead plant FAL than in PAB, in contrast with Calamagrostis where matter disappeared in Arrhenatherum at the rate of only a small change of N concentration was found at the 2.71 mg g−1 day−1 (Table 3). These differences can be end of the growing season 2002 and N resorption of 28% presumably caused by various chemical composition of from senescent aboveground biomass in 2003. Thereby, plant matter of these plant species, e.g., different C/N, N concentrations in FAL reached higher values in Ar- N/P ratios. Lower values of these ratios are reflected in rhenatherum (by 51% in 2002 and by 111% in 2003) faster decomposition processes (Berendse et al. 1987; than in Calamagrostis at the end of the growing seasons Ter Heerdt et al. 1991) and these conclusions were con- (Table 2). Overall, Calamagrostis resorbed markedly firmed by our results. The value of C/N ratio in Ar- more nutrients from aboveground biomass than Arrhen- rhenatherum fresh litter was assessed as 29, while that atherum. In the present study, a higher amount of N (by in Calamagrostis litter reached the value 35. The N/P 12%) was determined in TBB in Calamagrostis in com- ratio was also higher in the litter of Calamagrostis. parison with Arrhenatherum, while no substantial dif- Higher N input resulted in a moderate increase ferences were observed between P amounts of studied in litter decomposition rate in both studied species, plant species in November 2002. The nutrients which however statistically not significant (see results of the are resorbed during senescence are directly available ANOVA analysis in Table 3). Nevertheless, Arrhen- for further plant growth. On the other hand, nutrients atherum litter was decomposed faster (61% of litter dis- which are not resorbed, will be circulated through lit- appeared at the rate of 2.84 mg g−1 day−1), than the terfall. The litter must be decomposed and the nutri- litter of Calamagrostis (45% of plant matter was lost) ents contained in that litter must be remineralized to as a result of N addition (F = 43.8; P < 0.001). It im- become once again available for plant uptake (Aerts plies that a smaller increase in N availability in studied 1996). ecosystems does not need to modify substantially pro- Strong positive effect of N fertilization on the N cesses in decomposition chain. concentrations was observed in both Calamagrostis and Some differences were also found between stud- Arrhenatherum above-ground biomass (both PAB and ied plant species in the amount of released nutrients FAL). But P concentration significantly increased only from plant litter during decomposition processes (Ta- 678 P. Holub et al.

Table 4. Nutrient release in 2003 in Calamagrostis epigejos and Arrhenatherum elatius stands under ambient and N fertilized treatments after one year incubation 2002–2003. Diﬀ in % = Percentage diﬀerences shows a higher (+) or a lower (–) value of selected parameter in A. elatius stands in comparison with C. epigejos stands.

control N fertilized

Release of element C. epigejos A. elatius Diﬀ.(%) C. epigejos A. elatius Diﬀ.(%)

N(gm−2) 0.5 1.8 +260 0.4 2.9 +625 (%) 7.6 39.5 +420 5.0 46.0 +820 P(gm−2) 0.03 0.34 +1033 0.13 0.36 +177 (%) 6.6 65.8 +897 23.0 66.9 +191

Fig. 2. Scheme of different nutrient strategies of Calamagrostis epigejos and Arrhenatherum elatius. PAB – peak aboveground biomass; FAL – fresh aboveground litter; a. retranslocation of nutrients; b. nutrient amount during senescence; c. nutrient release during decomposition. ble 4). In the course of one year, 0.5 g N m−2 and 0.03 A higher N availability does not increase the re- gPm−2 were released from Calamagrostis litter rep- leased N quantity from Calamagrostis litter. However, resenting less than 8% and 7% of the original amount an increase was recorded in Arrhenatherum represent- of N and P accumulated in fresh litter before exposi- ing2.9gofloosenedNperm2 (46%). Application of tion. Kao et al. (2003) mentioned high retention of lit- N enhanced release of P from Calamagrostis litter to ter N but lower values for P retention in Calamagrostis 0.13 g P m−2 (decrease by 23%). However, the same canadensis. On the contrary, nutrient release per year effect was not found in fertilized Arrhenatherum stands reachedto1.8gNm−2 and 0.34 g P m−2 in Arrhen- (Table 4). Nevertheless, the quantity of released P was atherum, i.e., 40% and even 66%, respectively, of orig- nearly three times greater (0.36 g P m−2, 67%) than inal nutrient quantity in litter. On deforested sites in that in stands of Calamagrostis. Thus obtained data in- the Beskydy Mts, significant positive correlations were dicate that there are some differences between studied recorded between initial concentration of both N and P plant species in the amount of released nutrients dur- in plant litter of Calamagrostis arundinacea and litter ing decomposition processes. Important nutrients such decomposition and negative correlations between per- as N and P were released faster in Arrhenatherum than centage of C in litter, C/N ratios and decomposition it was in Calamagrostis (Table 4). (Tůma 2002). We can conclude that our study has shown that Different nutrient use strategies of expansive grasses 679 studied plant species can be associated with differ- 1998. Spatial variation in annual nitrogen deposition in a ru- ent growth strategies (Fig. 2). More effective nutrient ral region in Switzerland. Environ. Pollut. 102: 327–335. retranslocations from senescent aboveground parts of Fabšičová M., Sedláková I., Holub P., Tůma I., Chytrý M. & Záhora J. 2003. Nitrogen dynamics and expansion of the Ar- Calamagrostis epigejos into its surviving storage plant rhenatherum elatius in heathlands in the Podyjí Thaya River organs can play important role in biomass recovery Basin National Park, pp. 255–263. In: Pivničková M. (ed.), at the beginning of the next growing season. Hence Nature – supplementum, Agency for Nature Conservation and Landscape Protection of the CR, Prague, lower nutrients concentration in Calamagrostis litter Fanta J. 1997. Rehabilitating degraded forests in Central Europe and their slower release may be observed. On the con- into self-sustaining forest ecosystems. Ecol. Eng. 8: 289–297. trary, there is a substantially greater release of principal Fiala K., Holub P., Sedláková I., Tůma I., Záhora J. & Tesařová nutrients into soil environment during decomposition M. 2003. Reasons and consequences of expansion of Calama- grostis epigejos in alluvial meadows of landscape affected by of Arrhenatherum elatius due to both higher nutrient water control measures – a multidisciplinary research. Ekoló- concentrations in Arrhenatherum biomass (for recorded gia, Bratislava 22: 242–252. lower intensity of retranslocation, see text above) and Fiala K., Tůma I. & Holub P. 2011. Effect of nitrogen addi- faster decomposition processes in its stands. Therefore, tion and drought on above-ground biomass of expanding tall grasses Calamagrostis epigejos and Arrhenatherum elatius. these plant species can take up more released nutri- Biologia 66: 275–281. ents from soil environment and promptly allocate them Fiala K., Záhora J., Tůma I. & Holub P. 2004. Importance of in the biomass linked with rapid growth of individual plant matter accumulation, nitrogen uptake and utilization in plants (Fig. 2). expansion of tall grasses (Calamagrostis epigejos and Arrhen- atherum elatius) into an acidophilous dry grassland. Ekológia, Bratislava 23: 225–240. Acknowledgements Grime J.P., Hodgson J.G. & Hunt R. 1988. Comparative Plant Ecology: A Functional Approach to Common British Species. Allen & Unwin, London. This study was supported by Grants no. 206/02/P023 Holub P. & Záhora J. 2008. 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