Agrarian School of Viseu (ESAV)/Polytechnic Institute of Viseu (ISPV). Estrada de Nelas. Quinta da Alagoa-Ranhados Viseu.

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1 Instituto Ncionl de Investigción y Tecnologí Agrri y Alimentri (INIA) Forest Systems 211 2(3), Avilble online t ISSN: doi: eissn: Growth, soil properties nd folige chemicl nlysis comprison between pure nd mixed stnds of Cstne stiv Mill. nd Pseudotsug menziesii (Mirb.) Frnco, in Northern Portugl L. Nunes 1,5 *, J. Coutinho 2, L. F. Nunes 3, F. Cstro Rego 4 nd D. Lopes 5 1 Agrrin School of Viseu (ESAV)/Polytechnic Institute of Viseu (ISPV). Estrd de Nels. Quint d Algo-Rnhdos Viseu. Portugl 2 Chemistry Centre. University of Trás-os-Montes Alto Douro (UTAD). Apdo Vil Rel. Portugl 3 CIMO. School of Agriculture. Polytechnic Institute of Brgnç (UTAD). Cmpus de Snt Apolóni. Apdo Brgnç. Portugl 4 Instituto Superior de Agronomi. Centro de Ecologí Aplicd «Prof. Bet Neves». Tpd de Ajud Lisbo. Portugl 5 CITAB. University of Trás-os-Montes Alto Douro (UTAD). Apdo Vil Rel. Portugl Abstrct Ecosystems with mixed species compred to the ones with pure compositions provide broder rnge of options in the fields of biodiversity, conservtion, protection nd restortion. Industril plnttions in Portugl re mostly monocultures with the predominnce of coniferous forests, so the introduction of brodleves could be importnt for the biodiversity nd sustinbility of Portuguese forests. This study ims to present nd discuss field dt from pure nd mixed-species plnttions of Europen chestnut (Cstne stiv Mill.) nd dougls-fir [Pseudotsug menziesii (Mirb.) Frnco] with different intercropping densities in totl of 5 tretments with two replicte blocks. In respect to growth, the results showed significnt difference (P <.5, Scheffe) between tretments for survivl nd bsl re. Dimeter brest height (DBH), totl nd top height of the individul Cstne tree ws positively ffected by the presence of Pseudotsug. In generl, soil properties results showed higher fertility for mixed tretments compred with pure ones. Sttisticlly differences (P <.5, Scheffe) were observed in ph, P, Mn nd in the exchngeble cidity. Results for folir nlysis in N, P, C nd K concentrtions re higher for mixed tretments. The obtined results from this study indicte tht mixed plnttions hve positive effect in the productivity of the Cstne. Additionl key words: mixed-species plnttion; tree growth, soil fertility; folir nlysis. Resumen Comprción del crecimiento, propieddes del suelo y nálisis químico del follje entre mss purs y mixts de Cstne stiv Mill. y Pseudotsug menziesii (Mirb.) Frnco en el norte de Portugl Los ecosistems con especies mixts, en comprción con ls mss purs, proporcionn un gm más mpli de opciones en el cmpo de l biodiversidd, l conservción, l protección y l resturción. Ls plntciones industriles de Portugl son en su myorí monocultivos con predominio de bosques de conífers, por lo que l introducción de frondoss podrí ser importnte pr l biodiversidd y l sostenibilidd de los bosques portugueses. Este estudio tiene como objetivo presentr y discutir los dtos de cmpo de plntciones purs y mixts de especies de cstño y de beto de Dougls con diferentes densiddes de cultivo intercldo en un totl de 5 trtmientos con dos bloques. En lo que respect l crecimiento, los resultdos mostrron diferencis significtivs (P <,5) entre los trtmientos pr l supervivenci y el áre bsl. El diámetro norml (DAP), l ltur totl y l ltur dominnte del Cstño se vio fectdo positivmente por l presenci de Pseudotsug. En generl, ls propieddes del suelo mostrron un myor fecundidd de los trtmientos mixtos en comprción con los puros. Se observron diferencis estdísticmente significtivs (P <,5) en el ph, P, Mn y en l cidez intercmbible. Los resultdos de los nálisis folires de N, P, C y l concentrción de K son myores pr los trtmientos mixtos. Los resultdos obtenidos de este estudio indicn que ls plntciones mixts tienen un efecto positivo en l productividd del Cstño. Plbrs clve: plntciones mixts; crecimiento; fertilidd del suelo; nálisis folir. * Corresponding uthor: lnunes@esv.ipv.pt Received: Accepted:

2 Comprison of growth, soil properties nd folige nlysis 497 Introduction Society looks now for forest stnds in different wy. Public wreness nd the globl context of climte chnge re forcing the increse of mixed forest stnds. There is lso n incresing ecologicl view on the production nd mngement of the forest ecosystems (Knn, 1997). Nturl forests ecosystems re usully mixture of species (Luis nd Monteiro, 1998). There re critics bout forest prctices tht result in wide single-species plnttions tht differ rdiclly from nturl forest ecosystems (Brtelink, 2; Chen nd Klink, 23). Even keeping in mind the production perspective, Chen nd Klink (23) report tht mixed-species stnds re generlly thought to be more productive thn singlespecies stnds. These sme uthors complete this productive perspective, reporting tht mixed stnds re not only more diverse in respect to tree species, but lso provide more diverse hbitt nd my lso hve greter resilience to nturl disturbnces. For exmple, mixtures of trembling spen with conifers re more fire resistnt nd less susceptible to spruce budworm outbreks thn pure coniferous stnds. Mixtures of species lso provides diverse rnge of products, like fruit nd wood, s well s services (Kelty, 26), nd re more fvourble to nturl regenertion, llows better use of the soil (Luis nd Monteiro, 1998) nd proves to be n essentil tool for producers to diverse production. Forest nutrition mngement is n importnt fctor in the mngement of wood forests since the rtes of production re limited by the supply of one or more nutrients in lmost ll forests, mixture of species, ech with different nutrient requirements nd nutrient cycling properties nd efficiency of nutrient use (Khnn, 1997; Binkley nd Ryn, 1998; Rouhi-Moghddm et l., 28; Álvrez-Álvrez et l., 21). This wy, high rtes of production depend strongly on nutrient supply, efficiency of nutrient use, nd, thus, on species selection. Welke nd Hope (25) noted wide rnge of effects for mixed woods with respect to nutrient cycling. Studies exmining reltionships between site index nd soil chemicl properties report significnt reltionships which include the following soil chemicl mesures: totl N, vilble P, minerl soil ph, effective exchnge cpcity nd C:N rtio. In Portugl, lmost ll the commercil plnttions re single-species plnttions nd there is predominnce of coniferous forests. Being the single-species plnttions problemtic, in terms of risk of fires nd pthologic problems, the introduction of brodleves will be importnt for the sustinbility of Portuguese forests. Furthermore, questions bout single-species plnttions re being rised bout the sustinbility of their growth nd their effects on the site. These questions re relted with the removl of nutrients in the hrvest wood nd other tree components nd further losses my occur due to site mngement prctices (Khnn, 1997). The present study ims to compre growth, soil nd folir properties in mixed-species plnttions from pure composition nd evlute which stnd composition is more dvntgeous nd hve more productivity. This informtion could be n importnt tool to forest mnger s options. The first gol of this study is to nlyse if different species composition will hve impct on soil nutrients content, nd if in mixed stnds these nutritionl sttus will be different from monocultures. The second gol of the study is to understnd if these similrities or differences between soil nutritionl sttus will hve impct on the folir composition. Finlly it is lso importnt to understnd if growth will differ from mixed to pure plnttions nd in which level it will occur. Mteril nd methods Study re nd site chrcteristics Growth, soil properties nd folir nlysis were quntified within pure nd mixed-species plnttions of Europen chestnut (Cstne stiv Mill.) nd dougls-fir [Pseudotsug menziesii (Mirb.) Frnco] for different intercropping densities. Effects of species interctions on tree growth, concentrtions of soil nutrients, nd folir nutrients on trees were ssessed. According to Luis nd Monteiro (1998), Cstne stiv (Cs) is ntive deciduous brodlef species in Portugl, known since the Miocenic period nd cultivted since the Romn times. According with the Ntionl Forest Inventory (NFI, 25/6) Cstne covers n re of h (AFN, 21) nd in Portugl the cultivtion of chestnut trees is for wood nd minly for nut production, either for internl consumption or export (Vsconcelos et l., 21). Pseudotsug menziesii (Pm) is n exotic evergreen species, introduced in Portugl in 1846, in Sintr. Since then it hs been used in reforesttion projects, covering nowdys bout 4.2 h (Fontes et l.,

3 P 498 L. Nunes et l. / Forest Systems (211) 2(3), ); it proved to be well dpted to mountin sites nd shows lrge potentil for timber production. In mountin silviculture, Cstne nd Pseudotsug re two very interesting species, not only for timber production but lso with very high ecologicl potentil (minly the deciduous one) in Portugl. On mountin res, in the seventies, both species were extensively plnted in pure stnds, with promising results. The experimentl site is privte lnd locted t Bemlhevi (41 24 N nd 7 6 W), 55 km wy from Brgnç (Fig. 1), Trás-os-Montes region, in northestern Portugl. It is locted t n ltitude of 71 m bove se level nd is n lmost flt (2 ), NE turned (6 ) site. According to Luis nd Monteiro (1998), the soil t the site is litholic non-humic from sericitic schist. The nnul rinfll t Brgnç is 685 mm, nd the verge nnul temperture is 13. C. Rus (1997) compiled climte dt obtined by meteorologicl sttions spred cross the Brgnç district for wild studies, in period between 198 nd Vil Rel Brgnç Vil Rel Porto Lisbo Gurd Figure 1. Study re loction. S Brgnç Legend: N Study re km I A Temp ( C) Temp ( C) The men nd stndrd error (±S.E.) ws mde for this period nd the verge nnul temperture ws 12.5 C (±1.8 C) nd the nnul rinfll ws 69.1 mm (±8.8 mm) in the Brgnç district (Fig. 2). Experimentl design RR (mm) Figure 2. Climte digrm for the study re from the meteorologicl sttions of Brgnç since 198 to 1995 (Rus, 1997). The site ws composed by twenty one smpling plots with 64 plnts ech nd the trees spcing within the plnttions ws 4 2 m, estblished by Jime Sles Luis nd Mri Monteiro in the winter of 1981 (Luis nd Monteiro, 1998). The experimentl plnttions were estblished using rndomized complete-block design including tree replicte blocks with no buffer between tretments. In ech block nd tretment, designed by M s the initil word of «Mixture», 4 subsmples were instlled which covered two lines. Cstne stiv (s trget species - Cs) nd Pseudotsug menziesii (Pm) were plnted in four proportions (1Cs; 25Cs:75Pm; 5Cs:5Pm; 1Pm) ccording the next scheme: ) row mixtures with species chnging in the plnting line; M1-1 Cs nd 3 Pm in the line (25Cs:75Pm); M2-1 Cs nd 2 Pm in the line (25Cs:75Pm); M3-1 Cs nd 1 Pm in the line (5Cs:5Pm); b) line mixtures with species chnging between plnting lines; M4-1 line of Cs nd 1 line of Pm (5Cs:5Pm); M5-1 line of Cs nd 2 lines of Pm (25Cs:75Pm); nd c) monocultures; M6 - pure Cs (1Cs); M7 - pure Pm (1Pm) (Fig. 3). These proportions mke 7 tretments which were rndomly locted in ech block. The smpling plots size ws 512 m 2. In 25, ll the 7 tretments present in block I nd the tretments with the mixtures 5Cs:5Pm (M3 nd M4), present in block II burned. As result, block II just presents three mixtures proportions (1Cs M6; 25Cs:75Pm M1, M2, M5; 1Pm M7). All the plots RR (mm)

4 Comprison of growth, soil properties nd folige nlysis 499 B L O C K I M6 M4 M2 M7 M3 M5 M1 B L O C K II B L O C K M1 M6 M7 M2 M5 M3 M4 III M7 M3 M5 M4 M6 M1 M2 Figure 3. Lyout of permnent reserch plots composed by Cstne Stiv (O) Pseudotsug menziesii (Δ), in Bemlhevi (dpted from Luís nd Monteiro, 1998). The grey lines indicte the smpling plots burned. The blck lines indicte the smpling plots not nlysed becuse the repetitions in other blocks were burned. The rectngles represent the subsmples instlled in ech plot. instlled on block I weren t considered in this study. Also plots M3 nd M4 (proportions 5Cs:5Pm) in block III weren t considered due to the non existence of plots on block II with the sme proportions. Growth mesurements Dendrometric vribles, such s dimeter t brest height (DBH) nd totl height, were mesured for ech tree in ech smpling plot from block II nd block III. All trees were numbered nd repeted mesures were mde in ech tree in April 28 (Cstne nd Pseudotsug 27 yers old) nd April 29 (Cstne nd Pseudotsug 28 yers old). DBH ws mesured t 1.3 m from the ground nd totl height obtined by using clibrted pole using lwys the sme mesurement direction: center of the three-center of the plot, in order to void mesurements errors becuse of the non perfect circulrity of the stem. The verge of the DBH, totl height, bsl re, top height nd survivl percentge were clculted for ech plot in blocks II nd III. Since the plots were instlled height ws lwys mesured using n hypsometer from the sme distnce nd the sme direction. Once gin were void mesurement errors becuse of the non perfect circulrity of the stem. To find the men top height t ech smpling plot it ws considered the mximum height of the dominnt trees by verging the four highest trees for ech species. The increment in height nd DBH ws lso estimted bsed on mesures mde in 28 nd 29. The survivl ws mesured bsed on the mortlity rte, ccording to the percentge of ded plnts in the plnted totl in ech tretment in April of 29. Soil properties Soil smples were collected t two lyers-horizon A: -2 cm nd horizon B: 21-6 cm depths during Februry 21 using 7.6 cm dimeter core smpler (n = 4 cores/plot). These smples were collected in three proportions (1Cs; 25Cs:75Pm; 1Pm) t M1, M2, M5, M6 nd M7 tretments in blocks II nd III. Then the smples were ir-dried nd sieved with 2 mm screen before nlysis. Physicl (texture) nd chemicl nlysis, such s ph(h 2 O), orgnic mtter content, phosphorous (P), potssium (K), clcium (C), mgnesium (Mg), sodium (N), nitrogen (N), exchngeble cidity (Exc c), electricl conductivity (EC), were done in order to estimte the effect of plnttion type on soil fertility. Soil texture ws determined by the Bouyoucos hydrometer method (Bouyoucos, 1962). ph ws mesured using 1:2.5, soil:wter or KCl 1M. EC ws

5 5 L. Nunes et l. / Forest Systems (211) 2(3), determined using n Orion Ionlyzer Model 91 EC meter in 1:2.5, soil:wter solution. Soil orgnic crbon ws determined using n elementl nlysis equipped with n IR detection. The totl nitrogen ws mesured using semi Micro-Kjeldhl technique nd quntified by moleculr bsorption spectrophotometry (Bremner, 1996). The vilble P ws determined with spectrophotometer by using Olsen method (Homer nd Prtt, 1961). The exchngeble K, C, Mg nd N (by mmonium cette extrction t ph 7) were determined with tomic bsorption spectrophotometry (Bower et l., 1952). Exchngeble cidity ws determined by titrtion ccording to Thoms (1996). Folige nutrients The study ws crried out with the collection of 64 folige smples from the 1 smpling plots with the proportions 1Cs, 25Cs:75Pm, nd 1Pm present in blocks II nd III, mking 5 tretments (M1, M2, M5, M6 nd M7), in July of 21 (leves pek period of mturity). Ech folige smple ws composed by 3 leves collected from the top one third of the tree by clipping two smll distl twigs locted on the opposite sides of the crown. Four representtive trees (one in ech row of the sub-plot) per species were selected inside the smpling plots to collect the fully expnded leves (mture leves). The collected smples were oven-dried t 7 C to constnt weight nd grounded in mill to pss through.25 mm sieve before the chemicl nlysis. The nlysed nutrients were nitrogen (N), phosphorous (P), potssium (K), clcium (C), mgnesium (Mg) nd crbon (C). N, P nd K were nlyzed fter digesting the smple in concentrted H 2 SO 4 +H 2 O 2 using Se s ctlyst (Milles nd Jones Jr., 1996). N nd P were determined by moleculr bsorption spectrophotometry nd K by flme emission spectrophotometry. C ws determined by n elementl nlysis equipped with NIR detection. C nd Mg were determined using n tomic bsorption spectrophotometry fter wet digestion with HNO 3 nd HClO 4 (Milles nd Jones Jr., 1996). Sttisticl nlysis All sttisticl nlyses were mde using the SPSS v.18 softwre. Normlity of the vribles ws checked by Shpiro-Wilk test nd the homogeneity of the vrinces ws done by the Levene test. One-wy nlysis of vrince (ANOVA) ws used to compre tree growth, soil properties dt nd folir nutrients dt mong experimentl tretments. The Scheffe test ws used to seprte the verges of the dependent vribles which were significntly ffected by tretment. Dt from soil prmeters were nlyzed using two-wy ANOVA with tretments nd soil depth s the fctors. Significnt differences mong the tretments verges were tested t P <.5 using Scheffe test. Results Growth mesurements From the nlysis of Figure 4, nd in terms of survivl, there re significnt differences between pure nd mixed plnttions for both species (P <.5, Scheffe). The tretment M6 (1Cs) present the highest survivl vlue (85.16 ±.99%) for Cstne, only in tretment M2 (25Cs:75Pm), the survivl ws slightly lower (71.88 ±.88%). The tretment M5 (25Cs:75Pm) present the highest survivl vlue (89.58 ± 1.2%) for Pseudotsug (Fig. 4). There re no significnt differences on DBH in both species (P >.5, Scheffe) mong the tretments, so DBH of Cstne ws unffected by the presence of Pseudotsug in different proportions (Fig. 4b). The Pseudotsug mixed plnttions present slightly higher DBH vlues in tretment M5 (19.1 ± 2.61 cm) thn in pure plnttions, M7 (1Pm, ± 1.41 cm). For the Cstne, the heterogeneity is the most notble fct, with tretments of mixed plnttions presenting higher vlues thn the pure plnttions but lso the opposite; the verge of DBH rnged from cm to cm. There is not logicl evolution of this prmeter which llows the conclusion if mixed or pure plnttions re better. A similr behviour occurs in the totl height (Fig. 4c) but for both species. The verge of totl tree height for Cstne rnged from 6.73 m to 8.56 m nd for Pseudotsug rnged from m to m with no significnt difference (P >.5, Scheffe) mong the tretments in both species. The nlysis of top height shows the highest vlues for Cstne nd for Pseudotsug in M2 tretment (25Cs:75Pm) (Fig. 4d). With respect to the bsl re the Pseudotsug presents higher vlues thn the Cstne species. For

6 Comprison of growth, soil properties nd folige nlysis 51 ) Survivl (percent) 1 8 b b b Cs (M6) Tretments b DBH (cm) Cs (M6) Tretments b) c) 15 2 d) Totl height (m) Top height (m) Cs (M6) Tretments 1Cs (M6) Tretments e) Bsl re (m 2 /h 1 ) Cs (M6) c c Tretments Figure 4. Survivl (), DBH (b), totl height (c), top height (d) nd bsl re (e) of both tree species were seprtely compred. The letters on different column indicte different comprison. Men vlues with the sme letter within tree species do not differ significntly with ech other (P <.5, Scheffe). c b Cstne stiv Pseudotsug menziesii the Cstne, bsl re is lower in the mixed tretments thn in the pure ones. The sme occurs for the Pseudotsug (Fig. 4e). A generl study of the nlysed prmeters llows the conclusion tht in mixed plnttions the Cstne presents lower DBH vlues thn in pure one, but is tller. This mens competition between species tends to increse height nd decrese DBH. The behviour of the Pseudotsug is different becuse while DBH tends to increse in mixed stnds, top height tends to be stble. Figure 5 shows the DBH nd totl height mesured in 28 nd 29 nd the increment tht occurred in this period. Anlysing the DBH (Fig. 5) the M1 (25Cs:75Pm) tretment presents the highest vlues for ech species. The increment for the Cstne is lower in the mixed tretments thn in the pure ones. For the Pseudotsug the increment is higher in mixed tretments thn in pure ones (Fig. 5b). In respect to the totl height for the sme period, the M1 (25Cs:75Pm) lso presents the highest vlues for ech species (Fig. 5c). The increment for both species shows higher vlues in pure tretments (M6 for Cstne nd M7 for Pseudotsug) (Fig. 5d). When compring different estblishment procedures (M1, M2 nd

7 52 L. Nunes et l. / Forest Systems (211) 2(3), ) c) DBH (cm) Totl height (cm) Cs (M6) Tretments Tretments Cs 28 CS 29 Pm 28 Pm 29 Cstne stiv Pseudotsug menziesii 1Cs (M6) Tretments Totl height increment (cm) DBH increment (cm) Cs (M6) 1Cs (M6) Tretments b) d) Cs 28 CS 29 Pm 28 Pm 29 Cstne stiv Pseudotsug menziesii Figure 5. () DBH in 28 nd 29, (b) increment of DBH, (c) totl height in 28 nd 29, (d) increment of totl height during this period. M5), even with the sme proportion of trees (25Cs:75Pm), it cn be observed the heterogeneity of these vlues. Bsed on the results the Pseudotsug hs different behviour nd the DBH increment is even more heterogeneous with mixed tretments presenting higher increment vlues thn the pure ones (e.g. M2). In terms of the totl height increment the tendency is cler, with the pure tretments presenting higher increment vlues thn the mixed ones. In mixed tretments the Pseudotsug DBH increment ws positively ffected by the presence of Cstne (Fig. 5b). Khnn (1997) mde comprison study of growth in pure nd mixed stnds of Euclyptus globulus nd Acci mernsii nd hs concluded tht the DBH increment of Euclyptus ws higher in mixed tretments. Soil properties The obtined results showed few differences in soil properties mong the tretments. The soils were chrcterized s medium-textured. Soil ph (H 2 O), rnged from 4.69 to 4.85 in horizon A (-2 cm depth) in M2 nd M5 (25Cs:75Pm) tretments nd no significnt differences were found. In horizon B (21-6 cm depth) extreme vlues rnged from 4.59 to 4.89 in M6 (1Cs) nd M5 (25Cs:75Pm) tretments with significnt differences (P <.5, Scheffe) mong the tretments (Tble 1). There were no significnt differences (P >.5, Scheffe) between pure nd mixed tretments in terms of K (pure tretments with 52.5 nd 55. mg kg 1 ; mixed tretments with 49.25, 39.25, nd 53. mgkg 1, for horizon A). Nevertheless, the K content shows decrese in mixed tretments. In terms of exchngeble cidity, there re differences between the mixed tretments nlysed in both horizons (P <.5, Scheffe) (for horizon A the pure tretments present 2.53 nd 1.71 cmol (+) kg 1 ; mixed tretments with 1.88, 2.13 nd 2.34 cmol (+) kg 1, nd for horizon B the pure tretments present 3.69 nd 2.69 cmol (+) kg 1 ; mixed tretments present 2.5, 2.4 nd 2.38 cmol (+) kg 1 ). Once gin mixed tretments presented lower vlues thn the pure ones, excluding horizon A for pure Pseudotsug.

8 Comprison of growth, soil properties nd folige nlysis 53 Tble 1. Soil properties in 5 tretments in two soil lyers (A nd B horizons) with their stndrd error Depth 1Cs 25Cs:75Pm 25Cs:75Pm 25Cs:75Pm 1Pm Soil properties (cm) (M6) (M2) (M2) (M5) (M7) ANOVA b ph (H 2 O) (.7) 4.75 (.6) 4.69 (.6) 4.85 (.5) 4.83 (.7) ns (.7) 4.7 b (.5) 4.71 b (.6) 4.89 c (.5) 4.64 (.9) * ph (KCl) (.6) 3.81 (.9) 3.83 (.6) 3.84 (.6) 3.87 (.7) ns (.8) 3.76 (.8) 3.85 (.9) 3.79 (.9) 3.71 (.12) ns Orgnic mtter (g kg 1 ) (.3) 23.5 (.3) 25. (.2) 24.9 (.3) 23.3 (.3) ns (.1) 1.5 (.2) 12. (.2) 11.7 (.3) 14.1 (.1) ns P 2 O 5 (mg kg 1 ) (4.62) 12.4 b (2.15) 11.2 c (2.71) 9.1 d (1.92) 15.5 b (2.21) * (.3) 3.1 (.89) 3.9 (1.18) 1.9 (.42) 3.4 (1.2) ns K 2 O (mg kg 1 ) (5.86) (4.73) (4.44) 53. (7.2) 55. (8.98) ns (7.33) (5.1) 34. (2.56) 4. (4.34) 45.5 (6.14) ns C [cmol (+) kg 1 ] (.6).14 (.5).16 (.9).21 (.5).16 (.5) ns (.5).14 (.8).13 (.8).31 (.15).6 (.1) ns Mg [cmol (+) kg 1 ] (.5).9 (.2).11 (.5).15 (.4).16 (.6) ns (.5).1 (.2).3 (.1).43 (.28).6 (.2) ns K [cmol (+) kg 1 ] (.1).12 (.1).9 (.1).15 (.2).14 (.2) ns (.1).13 (.2).8 (.1).15 (.3).11 (.3) ns N [cmol (+) kg 1 ] -2.8 (.1).11 (.3).8 (.1).8 (.1).9 (.1) ns (.1).9 (.1).8 (.1).11 (.3).9 (.1) ns Exc c [cmol (+) kg 1 ] (.17) 1.88 b (.17) 2.13 b (.19) 2.34 b (.19) 1.71 c (.11) * (.46) 2.5 b (.21) 2.4 b (.38) 2.38 b (.24) 2.69 c (.38) * Totl N (g kg 1 ) (.14) 1.11 (.12) 1.11 (.13) 1.14 (.13) 1.14 (.13) ns (.3).61 (.8).61 (.7).61 (.13).72 (.7) ns EC (ds m 1 ) -2.4 (.1).4 (.1).3 (.1).3 (.1).3 (.1) ns (.1).3 (.1).2 (.1).2 (.1).2 (.3) ns b ANOVA results: ns = tret- Men vlues with the sme letter within the soil lyer do not differ significntly with ech other. ment effect not significnt. * P <.5 Scheffe. For P nd for horizon A, M6 (1Cs) tretment presents higher vlues (2.9 mgkg 1 ), which decreses with the decresing proportion of the Cstne mong the mixed tretments (12.4, 11.2 nd 9.1 mgkg 1 ). This mens tht higher proportions of Cstne results in higher vlues of P in the soil. It is lso interesting to report tht differences cn be observed mong the three mixed tretments. No sttisticlly significnt differences were observed for the orgnic mtter content between the tretments in both soil lyers (horizon A rnged from 23.3 to 26.5 gkg 1 nd horizon B rnged from 8.8 to 14.1 g kg 1 ), lthough it decreses with decresing of Cstne proportion in horizon A. C (vlues rnged from.14 to.21 cmol (+) kg 1 in horizon A nd from.6 to.31 cmol (+) kg 1 in horizon B), Mg (vlues rnged from.9 to.18 cmol (+) kg 1 in horizon A nd from.3 to.13 cmol (+) kg 1 in horizon B) nd totl N (vlues rnged from 1.11 to 1.31 gkg 1 in horizon A nd from.52 to.72 g kg 1 in horizon B) exhibited no significnt differences mong the soil horizons of tretments (P >.5, Scheffe). Also, no significnt differences were observed in the exchngeble N (vlues rnged from.8 to.11 cmol (+) kg 1 for both horizons) nd electricl conductivity content in both soil lyers between the tretments. A generic nlysis of the Tble 1 shows tht soils re not so different between pure nd mixed stnds. The only sttisticlly differences were observed for the ph in the horizon B, P in horizon A nd the exchngeble cidity for both lyers. Folige nutrients Tble 2 shows the results of folige chemicl nlysis. Once gin, nd reflecting the previous results

9 54 L. Nunes et l. / Forest Systems (211) 2(3), Tble 2. Folige chemicl nlysis in 5 tretments nd in two species (Cstne nd Pseudotsug) with their stndrd error Fully 1Cs (M6) 25Cs + 75Pm (M1) 25Cs + 75Pm (M 1 ) 25Cs + 75Pm (M5) expnded leves Cstne Cstne Pseudotsug Cstne Pseudotsug Cstne Pseudotsug Pseudotsug N (g kg 1 ) 19.5 (.56)* 19.9 (.42)* 9.2 (.25) 2. (.45)* 9.4 (.47) 23.4 b (.8)* 1.2 (.27) 9.5 (.3) P (g kg 1 ) 1.94 (.9) 2.21 (.1) 1.57 (.11) 2.6 (.11) 1.48 (.9) 2.22 (.18) 1.57 (.11) 1.38 (.1) K (g kg 1 ) 16.4 (.92) 16.4 (.5) 11.2 (.45) 16.1 (1.5) 1.5 (.66) 14.4 (.66) 11. (.41) 9.7 (.34) C (g kg 1 ) 4.3 (.4) 5.3 (.6) 4.8 (.51) 4.8 (.52) 4.7 (.55) 4.3 (.27) 5. (.28) 4.9 (.43) Mg (g kg 1 ) 3.73 (.46) 3.7 (.44) 1.55 (.6)* 3.3 (.36) 1.76 b (.1)* 3.88 (.51) 1.65 b (.6)* 1.87 c (.11)* C (g kg 1 ) (1.7) (8.78) (1.) (7.87) (6.41) (5.18) 51.1 (12.33) (4.76) Men vlues with the sme letter within the two species do not differ significntly with ech other. ANOVA results: * = tretment significnt (P <.5 Scheffe). of soil nlysis there is lmost no sttisticlly differences between pure nd mixed tretments for both species. The results of the nlysis of vrince (ANOVA) hve showed tht only for the Cstne there ws sttistic difference for the N content. In this cse, mixed tretments presented higher vlues for the N content nd the highest being in M5 (25Cs:75Pm) tretment with 23.4 gkg 1. Generlly, N nd P contents in Cstne were higher in the M5 (25Cs:75Pm) tretment. Vritions of N in folige rnged from 19.5 to 23.4 g kg 1 for Cstne nd from 9.2 to 1.2 g kg 1 for Pseudotsug. P limit vlues vry from 1.94 to 2.22 g kg 1 for Cstne nd from 1.38 to 1.57 gkg 1 for Pseudotsug. The others elements (K, C, nd C) did not present significnt differences for Cstne leves between pure nd mixed tretments, lthough K nd C present higher concentrtion (16.4 gkg 1 for K nd 5.3 gkg 1 for C) in M1 (25Cs:75Pm) tretment nd C present higher concentrtion, with gkg 1, in M6 (1Cs) tretment. Pseudotsug leves present significnt differences only for Mg mong the tretments, with the highest vlue observed for M7 (1Pm) tretment with 1.87 g kg 1. Discussion This study re is locted in plce where Cstne is ecologiclly well dpted. According to Fontes et. l. (23) the best sites for Pseudotsug growth re locted long north costl to centrl regions t ltitudes between 5 m nd 1, m with moisture deficit bove 1, m, nd s mentioned bove, this study re is instlled in plce in ccord with these prmeters. Cstne nd Pseudotsug survivl hve significnt differences in pure nd mixed plnttions. Survivl of Cstne is higher in pure thn in mixed plnttions with Pseudotsug. Rouhi-Moghddm et l. (28) reported tht survivl of Quercus in the pure plnttions ws lower thn in the mixed plnttions with Zelkov crpinifoli. The differences between our results nd those obtined by these uthors were probbly due to differences in nutrient nd light requirements of our species nd the ones studied by them. In terms of dimeter growth, we found tht there were no significnt differences between the different tretments, for both species nd in result the DBH ws not ffected by the different mixtures. A similr result ws obtined by Rouhi-Moghddm et l. (28). According to these uthors this results could be due to the similrity of the two species in their light needs. Bsl re for the Cstne nd the Pseudotsug plnttions showed significnt differences between the pure compred to the mixed plnttions. Our results were similr to those obtined by Khnn (1997), Prrott (1999), Montgnini (2) nd Piotto et l. (24); they found lrger bsl re for trget species in the mixed compred to the pure plnttions. Opposite results were obtined by Syyd et l. (26). In terms of totl height there were no significnt differences between pure nd mixed plnttions for both species. Although it is importnt to stress tht, nlyzing only the mixed tretments, it could be observed different results with the sme species composition, showing diversity of responses. Top height showed more cler response to species composition. Dominnt height is higher for mixed plnttions of Cstne thn in pure ones. This fct is not so cler for the Pseudotsug, where vlues re more similr. Bsed on the ssumptions of Kyhr et l. (1995), Tsug heterophyll does not pper to increse in site index with incresing nutrients, nd ssuming tht top height is good mesure of site index, we cn

10 Comprison of growth, soil properties nd folige nlysis 55 t lest ssume tht top height is depending on species composition, nd mixed plnttions promote higher vlues of this structurl prmeter. Luis nd Monteiro (1998) found, for the sme experimentl design, tht Cstne nd Pseudotsug show significnt differences in top height growth ptterns, but these ptterns were not influenced by the mixtures tested; this contrdict wht some yers lte ws found for the sme study re. Chen nd Klink (23) reported tht productivity ws not higher in mixed species stnds thus, they hve concluded tht mixed-species composition in western hemlock nd western redcedr stnds in southern costl British Columbi did not increse boveground productivity. Assuming tht the nlyzed structurl vribles re lso indictors of the stnd productivity, the obtined results were in greement with these ones, except for the top height. N is often the most importnt determinnt of plnt growth nd crop yield. Proteins, which re of gret importnce in mny plnt orgns, e.g. seeds, re compounds of nitrogen whilst chlorophyll, the green coloring mtter of the leves, lso contins the element. Our results showed tht soil N content does not vry between mixed nd pure plnttions. Rouhi-Moghddm et l. (28) reched similr results s this one, nd Montgnini (2) did not observed ny significnt differences in soil N between pure nd mixed plnttions. In terms of folir N concentrtions the results ws lower vlue thn the limit for possible deficiency (12 mg g 1, ccording to Will, 1985) for the pure plnttions of Pseudotsug, but not for the pure plnttions of Cstne. P plys n importnt role in the process of photosynthesis, nutrient trnsport, nd energy trnsfer. The P concentrtion in soil ws significntly different between pure nd mixed plnttions. It ws higher in pure plnttions for both species, even if the highest vlues were found for the pure Cstne tretments (M6). It is lso importnt to stress tht when testing the sme proportion of both species but chnging the design of the plnttion, P content chnges, which could be relted with the initil heterogeneity of the soil. In this cse P content results re not relted with chnges of species proportion (becuse they re the sme). The P limit vlues of folige concentrtions vry from 1. to 1.5 g kg 1 (Mnkovsk, 1996). In this study, ll the plots showed P folir concentrtions higher thn the reported limit vlues rnge. The obtined results for P soil content re exctly the inverse in terms of folir concentrtions, which mens tht while for soil P concentrtions vlues re higher in pure thn in mixed plnttions, in terms of P folir concentrtions results re the inverse. K is mjor plnt nutrient which hs to be ccumulted in gret quntity by roots nd distributed throughout the plnt nd within plnt cells. Membrne trnsport of K cn be medited by K chnnels nd secondry K trnsporters (Gierth nd Mäser, 27). Álvrez-Álvrez et l. (21) hve concluded tht for the hybrid chestnut plnttions the stnds with the highest growth rtes were chrcterized by high folir concentrtions of K, P nd C. The obtined results show no differences between the K concentrtion on folige, for both species, nd for pure nd mixed plnttions. A similr result ws obtined for the soil nlysis. In ll the tretments nlyzed, the K levels were higher thn the mrginl rnges for K (3-5 gkg 1, ccording to Will, 1985), which mens this nutrient is not conditioning plnts growth. According to Hong-Bo et l. (28), in plnt cells C plys role s second messenger, coupling wide rnge of extrcellulr stimuli with intrcellulr responses. In this study stisfctory folir C concentrtions (> 1 g kg 1, ccording to Will, 1985) were observed in ll the tretments. Vritions of this element in folige followed the order: mg g 1 for Cstne nd mg g 1 for Pseudotsug leves. These vlues re very similr to the ones found by Rouhi-Moghddm et. l. (28). For the soils there ws, once gin, no differences between ll tretments, which mens this study did not found differences between exchngeble C from mixed nd pure plnttions, for both horizons. In terms of Mg, the obtined vlues re much higher thn the optiml nutritionl vlues for Mg rnging from.6 to 1.5 g kg 1 (Stefn et l., 1997). In terms of soils nlysis, there were no sttisticlly differences between the Mg content for pure nd mixed plnttions, for both horizons. Vejre (1999) found tht for norwy spruce stnds the content of Mg nd C correlted significntly with stnd yield clss. Concerning C, folir nlysis showed no significnt differences between pure nd mixed plnttions for both species. The verge C vlue ws ner 54 gkg 1. For horizon B the ph ws sttisticlly different between tretments. Pure tretments of Cstne (M6) nd Pseudotsug (M7) differ from the mixed tretments nd M1 do not differ from M2 tretment but differ from M5. Although ll the mixed tretments nlyzed hve the sme species proportions the only difference ws the wy the trees were plnted. Generlly, when nlyzing soil horizons, the differences between pure nd

11 56 L. Nunes et l. / Forest Systems (211) 2(3), mixed plnttions were very smll. This indictes tht it might be result of firly short time frme, e.g., longer time spns re required for n influence of the tree species to develop in the minerl soil. Similr results were obtined by Brndtberg et l. (24), studying Betul spp. nd Pice bies in mixed stnds. These uthors reported tht mixture of brodlef tree species nd conifers re not complementry in nutrient uptke from the forest floor nd minerl soil. The results obtined with this study do not confirm wht Luis nd Monteiro (1998) stted bout the more productive mixtures when compred with the trditionl solution of Cstne stiv monocultures in n economic evlution. Nevertheless the experimentl design should be followed in the next couple of yers not only becuse improves the biodiversity but lso becuse, ccording to them, these mixtures perform better over time in productivity nd economic terms. So it will be necessry to monitor the tretments in the future nd evlute if mixed plnttions relly hve more ecologicl nd economic dvntges thn pure plnttions. The present study is preliminry study of the evolution nd behviour of these two species under different tretments; more definitive conclusions re expected in 1-15 yers when the effects t ges closer to the rottion ge cn be observed, especilly the effects induced by Pseudotsug menziesii. Acknowledgments This study ws funded by FCT reserch in project PTDC/AGR-CFL/68186/26 nd FCT Progrm SFRH/ PROTEC/5127/29. References AFN, 21. Inventário Florestl Ncionl, Portugl Continentl IFN Reltório finl. Autoridde Florestl Ncionl, Lisbo. 29 pp. ÁLVAREZ-ÁLVAREZ P., DÍAZ-VARELA E., CÁMARA- OBREGÓN A., AFIF-KHOURI E., 21. Relting growth nd nutrition to site fctors in young chestnut plnttions estblished on griculturl nd forest lnd in northern Spin. Agroforestry Systems 79(3), BARTELINK H.H., 2. A growth model for mixed forest stnds. For Ecol Mnge 134, BINKLEY D., RYAN M.G., Net primry production nd nutrient cycling in replicted stnds of Euclyptus slign nd Albizi fcltri. For Ecol Mnge 112, BOUYOUCOS G.J., Hydrometer method improved for mking prticle size nlysis of soils. Agron J 56, BOWER C.A., REITEMEIER R.F., FIREMAN M., Exchngeble ction nlysis of sline nd lkli soils. Soil Sci 73(4), BRANDTBERG P-O., BENGTSSON J., LUNDKVIST H., 24. Distributions of the cpcity to tke up nutrients by Betul spp. nd Pice bies in mixed stnds. For Ecol Mnge 198, BREMNER J.M., Nitrogen-totl. In: Methods of soil nlysis, Prt 3, 3 rd ed. (Sprks D.L. ed). Americn Society of Agronomy, Mdison, WI. pp CHEN H.Y.H., KLINKA H., 23. Aboveground productivity of western hemlock nd western redcedr mixedspecies stnds in southern costl British Columbi. For Ecol Mnge 184, FONTES L., TOMÉ M., THOMPSON F., YEOMANS A., LUIS J.F.S., SAVILL P., 23. Modelling the Dougls-fir [Pseudotsug menziesii (Mirb.) Frnco] site index from site fctors in Portugl. Forestry 76, GIERTH M., MÄSER P., 27. Potssium trnsporters in plnts - Involvement in K + cquisition, redistribution nd homeostsis. FEBS Letters 581, HOMER C.D., PRATT P.F., Methods of nlysis for soils, plnts nd wters. University of Cliforni, Agriculturl Sciences Publictions, Berkeley, CA. 39 pp. HONG-BO S., WEI-YI S., LI-YE C., 28. Advnces of clcium signls involved in plnt nti-drought. C R Biologies 331, KAYAHARA G.J., CARTER R.E., KLINKA K., Site index of western hemlock (Tsug heterophyt) in reltion to soil nutrient nd folir chemicl mesures. For Ecol Mnge 74, KELTY M.J., 26. The role of species mixtures in plnttion forestry. For Ecol Mnge 233, KHANNA P.K., Comprison of growth nd nutrition of young monocultures nd mixed stnds of Euclyptus globulus nd Acci mernsii. For Ecol Mnge 94, LUIS J.F.S., MONTEIRO, M.L., Dynmics of brodleved (Cstne stiv) conifer (Pseudotsug menziesii) mixed stnds in Northern Portugl. For Ecol Mnge 17, MANKOVSKA B., Geochemicl Atls of Slovki- Forest biomss (Slovk, English). Geologicl Service of Slovk Republic, Brtislv, ISBN: p. 87. MILLES H.A., JONES Jr. J.B., Plnt nlysis Hndbook II, MicroMcro Publishing Inc, Athens, Georgi, USA. 422 pp. MONTAGNINI F., 2. Accumultion in bove-ground biomss nd soil storge of minerl nutrients in pure nd mixed plnttions in humid tropicl lowlnd. For Ecol Mnge 134, PARROTTA J.A., Productivity, nutrient cycling nd succession in single- nd mixed-species plnttions of Csurin equisetifoli, Euclyptus robust, nd Leucen leucocephl in Puerto Rico. For Ecol Mnge 124, PIOTTO D., VIQUES E., MONTAGNINI F., KHANNA M., 24. Pure nd mixed forest plnttions with ntive

12 Comprison of growth, soil properties nd folige nlysis 57 species of the dry tropics of Cost Ric: comprison of growth nd productivity. For Ecol Mnge 19, ROUHI-MOGHADDAM E., HOSSEINI S.M., EBRAHIMI E., TABARI M., RAHMANI A., 28. Comprison of growth, nutrition nd soil properties of pure stnds of Quercus cstneifoli nd mixed with Zelkov crpinifoli in the Hyrcnin forests of Irn. For Ecol Mnge 255, RUAS L.M., Revisão de prâmetros meteorológicos locis pr indexção de risco de incêndio. Mster thesis. Universidde de Trás-os-Montes e Alto Douro, Vil Rel. 159 pp. SAYYAD E., HOSSEINI S.M., MOKHTARI J., MAHDAVI R., JALALI S.G., AKBARINIA M., TABARI M., 26. Comprison of growth, nutrition nd soil properties of pure nd mixed stnds of Populus deltoides nd Alnus subcordt. Silv Fennic 4(1), STEFAN K., FRUST A., HACKER R., BARTELS U., Forest folir condition in Europe. Technicl report. EC nd UN/ECE, Brussels, Genev. p. 27. THOMAS G.W., Soil ph nd soil cidity. In: Methods of soil nlysis, Prt 3, 3 rd ed. (Sprks D.L. ed). Americn Society of Agronomy, Mdison, WI. pp VASCONCELOS M.C.B.M., BENNETT R.N., QUIDEAU S., JACQUET R., ROSA E.A.S., FERREIRA-CARDOSO J.V., 21. Evluting the potentil of chestnut (Cstne stiv Mill.) fruit pericrp nd integument s source of tocopherols, pigments nd polyphenols. Industril Crops nd Products 31, VEJRE H., Stbility of Norwy spruce plnttions in western Denmrk soil nutrient spects. For Ecol Mnge 114, WELKE S.E., HOPE G.D., 25. Influences of stnd composition nd ge on forest floor processes nd chemistry in pure nd mixed stnds of Dougls-fir nd pper birch in interior British Columbi, For Ecol Mnge 219, WILL G.M., Nutrient deficiencies nd fertilizer use in New Zelnd exotic forests. FRI Bulletin No. 97. Rotoru, New Zelnd. 53 pp.