INTRODUCERE

Cercetri privind diversitatea productorilor din ecosistemele de fgete

i amestecuri de rinoase cu fag din Masivul CiucaCond. tiinific, Doctorand,

Nume i prenume Nume i prenume

Prof.Dr.Ing.Darie Parascan Buctaru Aliona-Mihaela (Sava)

Rezumatul tezei Introducere

Biodiversitatea caracterizeaz toate formele de via, sub toate aspectele, avnd n vedere varietatea speciilor, respectiv varietatea genetic din cadrul aceleiai specii, precum i a ecosistemelor.Exist mai multe definiii date biodiversitii, de-a lungul timpului, ns Namkoong,G. (1984), consider c biodiversitatea este un atribut al lumii vii, naturale i orice ncercare de cretere artificial a diversitii, fie i numai a unei pri locale a pdurii, este o aberaie.

ns, supraexploatarea i degradarea habitatelor a determinat o erodare a biodivarsitii n ecosistemul forestier, slbind astfel capacitatea lor de a asigura resursele i serviciile vitale. Biodiversitatea ocup astfel, o poziie critic ntre asigurarea de resurse naturale necesare societii umane i pstrarea la un nivel ridicat a calitii vieii pe Terra. Motivaia abordrii unor cercetri de biodiversitate o constituie, pe de o parte interesul pe care l prezint o asemenea problematic i pe de alt parte necesitatea cunoaterii biodiversitii fgetelor i a amestecurilor de fag cu rinoase din Ciuca, ecosistem mai puin investigat n acest domeniu. n lucrarea de fa, am abordat ca tematic biodiversitatea, deoarece este un concept de actualitate, intens studiat n zilele noastre ncepnd cu cele mai mici forme de via microorganismele, este deci un concept care face referiri la lumea vie, ca un ntreg.

Am ales ca zon de cercetare Masivul Ciuca, la nivelul cruia au mai fost ntreprinse diverse studii ecofiziologice, fitocenologice, mrturie fiind tezele de doctorat ale lui Vlonga, t., respectiv Ciuc, M., ns avnd n vedere faptul c, la nivelul acestui masiv nu a fost abordat biodiversitatea ecosistemelor forestiere, am realizat, n cadrul acestei teze, o analiz comparativ privind diversitatea fitocenozelor din aceast zon deoarece, prin aezarea lui, n partea central a Carpatilor, prin condiiile fizico- i fitogeografice, Ciucaul ofer o mare i interesant diversitate floristic. Astfel, cu ajutorul indicilor i indicatorilor consacrai, stabilii printr-o metodologie riguros i foarte bine elaborat, s-a realizat o ampl cercetare comparativ privind biodiversitatea fitocenozelor forestiere, reprezentate de dou tipuri de arborete, i anume arborete pure de fag i arborete de fag aflate n amestec cu rinoase.

Stadiul actual al cunotinelor n ara noastr La noi n ar au fost abordate cercetri nc de prin anii 1930-1940, cptnd un contur specific abia dup 1980 (dup Biri, I.A., 2001).

n ara noastr exist o vast literatur de specialitate referitoare la geobotanica i ecologia ecosistemelor forestiere, dintre cele mai vaste fiind dedicate fgetelor: Pauc, A. (1941), privind studiile fitocenologice efectuate n Munii Codru i Moma; Beldie, A. (1951) privind fgetele montane dintre Valea Buzului i Valea Ialomiei; Borza,A. (1959), privind flora i vegetaia din bazinul Vii Sebeului; Morariu, I. (1968), fitocenologia fgetelor de pe Mgura Codlei.

n literatura tiinific din ara noastr, primele abordri ale conceptului de diversitate, n sensul orientrilor moderne, pornite pe plan internaional, aparin lui Botnariuc, N. i Vdineanu, A. (1982), i Stugren, B. (1982).

Scopul cercetrilor

Scopul principal al acestei lucrri este de a aprofunda cunotinele privind biodiversitatea productorilor primari, din ecosistemele de fgete pure, precum i din ecosistemele de fag aflate n amestec cu rinoase, neafectate antropic, precum i n ecosistemele n care s-a intervenit cu diferite lucrri silviculturale.

Obiectivele urmrite

n vederea realizrii acestei lucrri, au fost stabilite urmtoarele obiective:

- determinarea ariei minime, pentru fiecare strat al fitocenozei;

-determinarea principalilor indicatori de cuantificare a biodiversitii;

- stabilirea diversitii fitocenozelor n arboretele neparcurse cu lucrri silviculturale (considerate martor);

-stabilirea diversitii fitocenozelor n arboretele parcurse cu diferite lucrri silviculturale;

-evidenierea influenei diferitelor intervenii silviculturale asupra diversitii productorilor primari, prin analiza unor relaii dintre diversitatea structural i cea specific ;

- analiza structurilor orizontale i verticale a arboretelor studiate i a influenei acestora asupra diversitii productorilor primari.

Locul cercetrilorCercetrile au fost efectuate n ecosistemele forestiere de fgete pure, precum i n amestecuri de fag cu rinoase, situate n Masivul Ciuca.

Au fost parcurse patru uniti de producie, i anume Dlghiu (U.P I), Valea Zizinului (U.P II), Valea Satului (U.P III) i Izvoarele Buzului (U.P IV).

Cadrul fizico- i fito-geografic al Masivului Ciuca

Masivul Ciuca este aezat n partea central a Carpailor, n grupul muntos al Carpailor de Curbur ( n sud estul teritoriului). Este cuprins ntre 450 25i 450 35 latitudine nordic i 25 0 55i 26 0 4 longitudine estic i ocup o arie destul de restrns (circa 200 km2), fa de alte uniti montane din ar.Limitele fa de munii nconjurtori sunt reprezentate de vile rurilor, iar ntre acestea i nlimile maxime se ntlnesc denivelri de aproximativ 1000 m. Metode de cercetare

Pentru efectuarea cercetrilor n teren, s-au ntreprins urmtoarele:

- o documentare riguroas din amenajamentele ocoalelor silvice O.S Kronstadt, Judeul Braov, respectiv O.S Trlungeni, din localitatea Trlungeni, Judeul Braov;

- analiza hrilor din amenajamentele respective;

- recunoaterea general a terenului, precum i parcurgerea acestuia, pentru identificarea arboretelor dorite: arborete pure de fag i arborete de fag n amestec cu rinoase, aflate la vrste diferite: arborete tinere, pn n 70 de ani i arborete btrne, pn n 130 de ani;

- n fiecare tip de arboret, s-au ales cupluri experimentale constituite din dou variante: martor i parcurse cu lucrri silviculturale;

- au fost luate n studiu arborete parcurse cu lucrri de tipul rriturilor, respectiv tieri progresive, arboretele martor fiind parcurse cu cel mult lucrri de ntreinere, de igien; au fost alese arboretele martor n care impactul antropic a fost ct mai redus posibil.

- la stabilirea perechilor de arborete, constituite din cele dou variante (martor i parcurse cu lucrri), s-a urmrit o ct mai bun similitudine n ceea ce privete condiiile staionale i de vegetaie.

- dup cum s-a precizat n capitolul anterior, au fost alese 24 de cupluri experimentale, cu cte dou variante martor i parcurs cu lucrri silviculturale (n total 48 de variante).La elaborarea metodicii de cercetare au fost consultate i lucrrile: Biri, I.A (2001), Petrescu, M. (2004), Geambau, T. (2007), Dnil, G. (2009). Rezultatele cercetrilor

Aria minim determinatan lucrarea de fa, stabilirea ariei minime s-a determinat pentru stratul ierbos, att n arboretele pure de fag (tinere i btrne), ct i n arboretele amestecate de fag cu rinoase ( tinere i btrne), urmnd ca n final s se realizeze o comparaie privind diversitatea speciilor ntlnit la nivelul acestor dou tipuri de arborete, luate n studiu.

Au fost cercetate cte 24 de cupluri , cu variante martor i parcurse cu lucrri, pentru arboretele pure de fag, tinere i btrne, i amestecate de fag cu rinoase, tinere i btrne.

S-a notat cu C, fiecare cuplu experimental, iar variantele din diferitele uniti amenajistice, au fost notate cu m pentru variantele martor, i cu p,pentru variantele parcurse cu diferite lucrri (tieri progresive i rrituri).

Bogia de populaii specifice

n toate perechile experimentale, arborete martor arborete parcurse cu lucrri, numrul de populaii specifice variaz, astfel nct sunt mai puine n martor i mai multe n cel parcurs cu tieri. De asemenea, numrul mai mare de populaii specifice identificate se ntlnete n arboretele amestecate, n primul rnd n arboretele amestecate btrne, urmate fiind de cele tinere. n arboretele pure, numrul de populaii este ceva mai mic, acest fapt se explic prin aceea c arboretele amestecate prezint o mai mare variabilitate de specii, att arborescente, ct i arbustive, dar mai ales ierboase, ceea ce le confer o mai mare stabilitate n timp, asigurndu-le astfel, perenitatea i variabilitatea.Abundena n populaii specifice

Abundena este un indicator structural, de evaluare cantitativ, prin numrul de indivizi ai fiecrei populaii specifice, din cadrul fitocenozelor. Acest indicator a fost calculat pe baza datelor primare, prelevate de pe teren, att pentru fiecare strat al fitocenozei, ct i pentru arboretul n ansamblu.La analiza perechilor de variante parcurse cu cele dou tipuri de lucrri, rrituri i tieri progresive, se poate observa o tendin de cretere a coeficientului de variaie odat cu creterea numrului de specii mai ales pentru variantele parcurse cu tieri progresive, unde i numrul speciilor identificate este mai mare Densitatea i frecvena speciilor

Pentru determinarea densitii au fost luate n calcul absolut toate speciile identificate din fiecare suprafa de prob, numrul de indivizi al fiecrei specii a fost raportat la hectar, iar frecvena (n cazul ei a fost luat n considerare doar straturile ierbos i arbustiv), a fost calculat prin intermediul coeficientului de variaie al frecvenei. Diversitatea specific - indicele diversitii ShannonWiener (Hs)S-a urmrit modul de variaie al indicelui Shannon-Wiener (Hs) pentru diversitatea specific cu numrul de specii pentru toate tipurile de arborete, pentru variantele martor comparativ cu cele parcurse cu rrituri, respectiv cu tieri progresive.

Particulariti privind diversitatea floristic

n ceea ce privete aria minim determinat, putem spune c, aceasta are mrimi diferite, n funcie de tipul de arboret luat spre cercetare, n cele 24 de suprafee de cercetare, respectiv 48 de variante (martor i parcurse cu tieri), au fost identificate 261 de specii de plante vasculare, numrul de specii fiind mai sczut n arboretele martor (110), n care i intervenia antropic a fost mai sczut, numrul mai ridicat (216) fiind n cele parcurse cu tieri (rrituri, respectiv tieri progresive). Dac facem referiri la fiecare tip de arboret n parte, putem spune c, din totalul speciilor identificate, 17 sunt specii arborescente, 18 specii sunt arbustive i 226 de specii sunt ierboase.

Pentru analiza abundenei, s-a utilizat coeficientul de variaie al abundenei (s%a), care crete odat cu creterea numrului de specii, dar total diferit pentru fiecare strat de vegetaie n parte. O cretere mai accentuat se constat la nivelul stratului ierbos, mai puin accentuat la stratul arbustiv, i cea mai redus cretere, se ntlnete la stratul arborescent, aceasta explicndu-se prin numrul de specii, care scad de la stratul ierbos spre cel arborescent.

Frecvena, a fost analizata doar la nivelul straturilor ierbos i arbustiv, deoarece stratul arborescent cuprinde un numr redus de arbori. De asemenea, exist aceeai tendin de cretere a coeficientului de variaie al frecvenei odat cu creterea numrului de specii. n ceea ce privete indicele Shannon Wiener, a fost i el analizat n raport cu numrul de populaii specifice identificate. La fel, ca i la ceilali indici luai n studiu, i valorile acestui indicator cresc odat cu creterea numrului de populaii specifice

La gruparea variantelor pe tipuri de arborete, pure (tinere i btrne), precum i amestecate (tinere i btrne), se observ creterea diversitii n cadrul arboretelor amestecate, i mai ales la cele btrne, unde i numrul de specii identificate, este mai mare.

Indicatori ai diversitii stratului arborescent

n lucrarea de fa vom face referiri la diversitatea stratului arborescent, diversitate prezentat att n mod general, la nivelul masivului, ct i calculat n fucie de suprafaa de baz, din fiecare tip de arboret studiat (fgete pure i arborete de fag n amestec cu rinoase, tinere i btrne), cu variantele martor i parcurse cu lucrri.

Compoziia stratului arborescent

Compoziia stratului arborescent calculat n funcie de suprafaa de baz

Compoziia stratului arborescent a fost calculat procentual, n funcie de suprafaa de baz, pentru fiecare specie care l alctuiete.

Prin analiza compoziiei arboretelor luate n studiu , putem spune c, o mare proporie este ocupat de trei specii, i anume - fag, brad i molid. Cu participare mult mai redus, mai apar carpenul, paltinul de munte. Un procent mai ridicat l are fagul, urmat fiind de brad i molid.Indicatori ai structurii orizontale si verticaleS-au folosit modele de distribuie ale numrului de arbori pe categorii de diametre, respectiv pe categorii de inaltimi. Influena structurii orizontale asupra diversitii specifice

Pentru reprezentarea influenei structurii orizontale asupra diversitii specifice, s-a utilizat, ca msur a diversitii, coeficientul de variaie al diametrelor, raportat la numrul de specii identificate n fiecare tip de arboret luat n studiu.De asemenea, valorile mai mari ale coeficientului de variaie a diametrelor se ntlnesc n cadrul arboretelor relativ pluriene, fa de cele relativ echiene.

Influena structurii verticale asupra diversitii specificeLa fel ca i la analiza structurii orizontale, i n cadrul structurii verticale, au fost folosii aceeai indicatori ai diversitii specifice, au fost luai n calcul indicele diversitii specifice.

La reprezentarea grafic a modului de variaie al numrului de specii n funcie de coeficientul de variaie al nlimilor, se poate remarca o foarte mare asemnare dintre variaia numrului de specii i reprezentarea grafic al coeficientului de variaie al diametrelor, acest fapt fiind normal dac inem cont de corelaia foarte strns dintre diametre i nlimi, dar bineneles i dintre coeficienii de variaie al celor dou mrimi.

Particulariti privind diversitatea structural

La nivelul fgetelor pure, specia dominant o reprezint fagul, n proporie de 93%, n fgetele tinere, varianta martor, respectiv 99%, n variantele parcurse cu lucrri. n cazul fgetelor pure btrne, proporia fagului este de 93%, pentru ambele variante, martore i parcurse cu lucrri. Trebuie s precizm faptul c , pe lng fag, ca specie dominant, n proporii foarte reduse se ntlnesc i molidul, bradul, cu procentaje cuprinse ntre 2% i 5%.

n cadrul arboretelor de fag tinere, aflate n amestec cu rinoase, ca specie dominant este tot fagul, dar n proporii ceva mai reduse 59% (pentru variantele mator), respectiv 63% (pentru variantele parcurse cu tieri), iar n cadrul arboretelor btrne, proporia este ceva mai sczut 51% (pentru variantele martor), respectiv 49% (pentru variantele parcurse cu tieri). Menionm c, specia dominant, fagul, este urmat, n proporii destul de sczute, de larice, pin, paltin de munte, anin, plop tremurtor, tei, carpen.

n cazul repartiiei arborilor pe clase de diametre, s-a constatat o mare diversitate structural a arboretelor, existnd att arborete relativ echiene, ct i relativ pluriene, prezente fiind att n cadrul variantelor considerate martor, ct i n cadrul celor parcurse cu tieri.

Pentru calcularea frecvenei relative a arborilor, s-a utilizat indicele Shannon-Wiener, al diversitii structurii orizontale, care n funcie de numrul de arbori, s-a constatat scderea diversitii structurii orizontale (odat cu scderea numrului de arbori). Dac analizm variaia acestui indice n raport cu suprafaa de baz, se constat aceeai scdere a diversitii, odat cu mrirea intensitii extragerilor, deci cu scderea suprafeei de baz, corelaia fiind mult mai evident n cadrul arboretelor parcurse cu tieri, datorit scderii variabilitii claselor de diametre.

n ceea ce privete structura vertical, putem spune c exist o mare asemnare cu cea orizontal, dar n acest caz facem referiri la repartiia numrului de arbori pe categorii de nlimi.Dac raportm modul de variaie al indicelui diversitii structurii verticale bazat pe frecvena relativ a arborilor pe clase de nlimi, odat cu modificarea numrului de arbori, se constat scderea diversitii structurii verticale odat cu scderea numrului de arbori, deci scderea diversitii struturii verticale odat cu scderea numrului de arbori, este cauzat de reducerea variabilitii claselor de nlimi. Influena interveniilor silviculturale asupra diversitii productorilor primari

Lucrrile silviculturale executate n cele dou tipuri de arborete, fgete pure (tinere i btrne), respectiv, arborete de fag aflate n amestec cu rinoase (tinere i btrne), sunt rriturile i tierile progresive.

n ceea ce privete tierile progresive, acestea au fost executate la nivelul arboretelor btrne att pure, ct i aflate n amestec cu rinoase. n aceste tipuri de arborete, din punct de vedere al compoziiei, specia dominant este reprezentat de fag, urmat fiind de brad, pin, molid, larice, carpen, plop tremurtor, anin, toate n proporii reduse.

Indicatorii utilizai pentru caracterizarea diversitii specifice sunt coeficientul de variaie a abundenei s%a, coeficientul de variaie a frecvenei s%f i indicele diversitii specifice Shannon-Wiener - Hs). n general, aceti indicatori ai diversitii specifice, care au fost calculai, au tendin, aa dup cum s-a artat n capitolele anterioare, de cretere odat cu creterea numrului de specii, ns, apar i abateri de la aceast situaie, de exemplu, coeficientul de variaie a abundenei (s%a) la arboretele parcurse cu tieri, precum i indicele diversitii specifice (Hs) la stratul arborescent scad cu creterea numrului de specii. La stratul arborescent, diversitatea specific scade ca urmare a recoltrii de arbori, ceea ce duce la dispariia unor specii din acest strat.

Dac analizm influena structurii orizontale asupra diversitii specifice, utiliznd suprafaa de baz a arboretului (Gr), se constat scderea diversitii specifice odat cu scderea suprafeei de baz. Tratamentul tierilor progresive ine cont de dinamica regenerrii, iar recoltarea arborilor se face n funcie de dinamica seminiuluin consecin, are loc fie o dezvoltare puternic a seminiului, care mpiedic instalarea altor specii vegetale, fie are loc o cretere a diversitii specifice odat cu creterea suprafeei de baz; o alt cauz, o mai poate reprezinta, de asemenea i distrugerea straturilor ierbos, arbustiv, dar i a seminiului instalat dup ultima tiere, cu ocazia unei noi exploatri, fie pentru lrgirea ochiurilor, fie pentru racordare.

n ceea ce privete structura vertical, se constat o uoar cretere a diversitii specifice sau a numrului de specii, odat cu scderea coeficientului de variaie a nlimilor.

n ceea ce privete rriturile, acestea au fost executate doar la nivelul arboretelor tinere (fgete pure i arborete de fag n amestec cu rinoase). i n aceste tipuri de arborete, structura lor difer, n sensul c sunt att relativ echiene, ct i relativ pluriene. Din punct de vedere al compoziiei, putem spune c, fagul, care este specia dominant, se afl ntr-un procentaj mult mai mare, mai ales n fgetele pure, aa dup cum am amintit i n subcapitolul anteriror. n cadrul fgetelor pure mai apar ntr-un procentaj mai redus bradul, molidul, iar n cadrul arboretelor amestecate mai apar, alturi de aceste dou specii i carpenul, plopul tremurtor, aninul, laricele.

Dup cum am artat, indicatorii diversitii specifice au tendin de cretere odat cu creterea numrului de specii, ns, apar i aici abateri de la aceast situaie, de exemplu, coeficientul de variaie a abundenei (s%a) la arboretele parcurse cu tieri, precum i indicele diversitii specifice (Hs) la stratul arborescent scad cu creterea numrului de specii, ns trebuie precizat faptul c, n urma rriturilor, se extrage un numr relativ redus de arbori,respectiv uniform, astfel nct numrul speciilor care se instaleaz, este ceva mai redus comparativ cu arboretele parcurse cu tieri progresive.

Concluzii generale

n urma cercetrilor efectuate i a rezultatelor obinute n ecosistemele de pdure din Masivul Ciuca, se pot desprinde urmtoarele concluzii generale, i anume:

n ceea ce privete diversitatea productorilor primari- Bogia n specii este mai mare n arboretele parcurse cu tieri progresive, unde s-au identificat 180 de specii (arboretele btrne de fag aflate n amestec cu rinoase, respectiv fgetele pure), i este mai redus n arboretele parcurse cu rrituri, unde numrul speciilor este mai mic, circa 81 (arboretele tinere de fag aflate n amestec cu rinoase, respectiv fgetele tinere).

- n urma analizei variabilitii abundenei, s-a constatat c aceasta crete odat cu creterea numrului de specii, ns n mod diferit pentru fiecare strat de vegetaie, respectiv pentru fiecare tip de tiere.

- Din punct de vedere al frecvenei speciilor, coeficienii de corelaie sunt mai mari pentru stratul ierbos, i au valori mai apropiate la nivelul arboretelor aflate n amestec cu rinoase, ceea ce este normal, dac avem n vedere faptul c i numrul de specii ierboase pentru aceste tipuri de arborete, este mai mare.

- Din analiza indicelui diversitii specifice Shannon-Wiener rezult c, att pentru straturile ierbos i arbustiv, fie luate separat, pe cele dou variante martor i parcurse cu tieri, fie luate pe cele dou straturi de vegetaie, indicele diversitii crete odat cu creterea numrului de specii.

n ceea ce privete structurile orizontale i verticale ale stratului arborescent

-n fgetele pure, specia dominant este, fagul, aflat ntr-o proporie de 93-99%, prezente fiind i specii ca bradul, molidul, dar n proporii foarte reduse 2-5%.

-La nivelul arboretelor de fag, aflate n amestec cu rinoase, specia dominant este tot fagul, dar ntr-o proporie ceva mai redus 49-63%, acest fapt datorndu-se prezenei altor specii, n diferite proporii: carpenul, paltinul de munte, gorunul, teiul, ulmul, frasinul, paltinul de cmp, aninul alb.

- n ceea ce privete influena structurii arboretelor supuse celor dou tipuri de intervenii silviculturale asupra diversitii productorilor primari

- Pentru arboretele parcurse cu rrituri, diversitatea specific (Hs) are o tendin cresctoare pe msur ce suprafaa de baz scade.

- Dac se ia n calcul coeficientul de variaie a diametrelor, ca indicator al structurii orizontale, i se urmrete variaia diversitii specifice sau bogia n specii, se constat aceeai dependen, de cretere a acestora din urm pe msur ce diversitatea structurii orizontale scade.

- Influena structurii verticale asupra diversitii specifice, s-a manifestat ntr-un mod asemntor cu structura orizontal.

Recomandri pentru producie

-S se evite pagubele i degradrile ce au loc la aplicarea tehnicilor de intervenie i de exploatare a materialului lemnos.

- Aplicarea unor asemenea intervenii conduc att la creterea diversitii structurale a stratului arborescent ct i la apariia i conservarea unui numr mai mare de productori primari n celelalte straturi fitocenotice ale ecosistemului.

- S se aplice msuri ecologice de exploatare, adaptate condiiilor particulare din fiecare unitate de exploatare n parte, n funcie de orografia terenului i de starea seminiului, pentru asigurarea regenerrii naturale i conservarea biodiversitii.

Contribuii personaleDintre contribuiile personale, cu caracter de originalitate, amintim urmtoarele :

- s-au cercetat diversitile specifice i structurale, n premier, a ecosistemelor forestiere reprezentate de fgete, ct i n cele de fag n amestec cu rinoase, din Masivul Ciuca;

- s-a analizat comparativ influena rriturilor i a tierilor progresive, aplicate n zona studiat, asupra diversitii specifice productorilor a primari;

- s-a stabilit bogia n specii, a abundenei, a densitii, a frecvenei i a diversitii specifice, prin indicatori consacrai, pentru regiunea luat n cercetare;

- s-au studiat, indicatorii biodiversitii, comparativ, pentru ambele variante luate n cercetare, pentru fiecare tip de intervenie n parte, precum i pentru fiecare strat fitocenotic, analizat separat;

Research on diversity producers of beech ecosystems and mixed beech-conifers forests, from Ciuca MassifScientific, Phd.

Name and first name Name and first name

Prof.Phd. Eng. Darie Parascan Biol.Bucataru Aliona-Mihaela (Sava)

ABSTRACTIntroduction

Biodiversity characterizes all life, in all, given the variety of species, that genetic diversity within a species and of ecosystems.There are many definitions of biodiversity, over time, but Namkoong, G. (1984), believes that biodiversity is an attribute of the living world, natural and artificial any attempt to increase diversity, if only the local part of the forest, is an aberration.

However, over exploitation and habitat degradation caused an erosion of biodiversity the forest ecosystem, thus weakening their ability to provide vital resources and services. Biodiversity thus occupy a critical position between providing the necessary natural resources and preservation of human society to a high quality of life on Earth.

The motivation of biodiversity research approach consists on the one hand the interest you have such problems and on the other hand need beech forests and biodiversity knowledge mixtures of beech and pine Ciuca, ecosystem less investigated in this field. In this paper, we addressed the theme of biodiversity, because it is a current concept, widely studied today - starting with the lowest life forms - microorganisms, is therefore a concept that refers to the living world as a whole. We chose Ciucas research area in which the various studies were undertaken ecophyziolacal, phytocenologic, the testimony of his doctoral thesis Vlonga, St., respectively Ciuc, M., but the fact that, at this solid was not addressed biodiversity of forest ecosystems, we achieved in this thesis, a comparative analysis of diversity in the area; phytocoenoses by placing him in the central part of the Carpathians, physical conditions and are disposed, Ciucas offers a large and interesting floristic diversity. Thus, indices and indicators renowned, established through a rigorous and well developed methodology was carried out an extensive comparative research on forest biodiversity phytocoenoses represented by two types of stands, namely pure stands of beech and mixed beech conifers forests stands.The current state of knowledge in our country

In our country research were discussed as early as 1930-1940 years, getting a specific shape only after 1980 (after Biri, IA, 2001).In our country there is a vast literature on geobotany and ecology of forest ecosystems, of the largest beech forests are dedicated to: Pauc, A. (1941), the studies performed phytocenologic Mountain Forest and Moma, Beldie, A. (1951) on beech mountain and Ialomita Valley of Buzau Valley, Borza, A. (1959), the flora and vegetation of the valley basin Sebes, Morariu, I. (1968), phytocoenology beech forests of the Magura Codlea.The scientific literature of our country, the first approaches to the concept of diversity, the meaning of the modern international started, belong to Botnariuc, N. and Vadineanu, A. (1982), and Stugren, B. (1982).Beech and beech trees in the resinons mixture.Purpose, objectives and research site

Purpose of the research

The main purpose of this paper is to deepen knowledge on biodiversity primary producers of pure beech ecosystems and the ecosystems of beech in mixture with pine, unaffected man-made, and the ecosystems in which it occurred with different silvicultural works.

The objectives

In order to accomplish this work, were set the following objectives:

- Determining the minimum area for each layer of phytocenosis;-determination of the main indicators measuring biodiversity;- Establishing diversity in witness stands phytocoenoses with silvicultural work (considered a witness);-establish diversity in the stands taken by different phytocoenoses silvicultural work;-highlighting the influence of different silvicultural interventions on the diversity of primary producers, by analyzing relationships between structural diversity and specific;- Analysis of horizontal and vertical structures of the stands studied and their influence on the diversity of primary producers. Place of research

Research has been conducted in pure beech forest ecosystems, as well as mixtures of beech and pine, located in Ciucas.We had to pass four production sites, namely Dlghiu (UP I) Zizinului Valley (UP II), Valley Village (UP III) and springs lip (UP IV).The physical-and phyto-geographical Ciucas

Ciucas is located in the central part of the Carpathians, the Carpathian mountain group of curvature (in the south - eastern territory). 25' is between 450 450 35 'north latitude and 25 0 55'i 26 0 4' east longitude and occupies a relatively small area (about 200 km2), to other units ar.Limitele mountain to surrounding mountains are represented by river valleys and between them and meet maximum height of 1000 m gradient.Research Methods

For research in the field have done the following:- Rigorous documentation of forest management plans OS districts Kronstadt, Braov County, that OS Tarlungeni, the city Tarlungeni, Brasov;- Analysis of maps of the respective management plans;- General recognition of the land and its completion, to identify desired stands: pure stands of beech and beech trees mixed with resin, at different ages: young trees, up to 70 years old and stands up in 130 years;- Every type of trees, were chosen experimental couples consist of two types: control and covered with silvicultural work;- Have been studied trees covered with works such rarerly works, respectively progressive cuts, stands witness is taken up with maintenance, hygiene, have been chosen stands witness that human impact has been as low as possible.- To establish pairs of trees, consisting of the two variants (blank and completed the work), has sought a better similarity in terms of site conditions and vegetation.- As mentioned in the previous chapter, 24 couples were chosen experimental, with two options - control and traveled with silvicultural work (a total of 48 variants). In developing research methodology and works were consulted: Biri, IA (2001), Petrescu, M. (2004), Geambasu, T. (2007), Danila, G. (2009).Results of research

Minimum area determinated

In this paper, setting minimum area herbaceous layer was determined for both pure beech stands (young and old) and in mixed stands of beech and pine (young and old), and in the end to make a comparison species diversity found within these two types of trees, studied.Were examined for 24 couples, with version control and covered with paper for pure stands of beech, young and old, and mixed beech and pine, young and old.Noted with "C", each couple experimental and different variants amenajistice units were marked with "m" for options blank and "p" to pass by various work options (progressive cuts and rarerly cuts).The richness of specific populations

In all experimental pairs, witness trees - trees covered with papers, the number of specific populations vary, and are therefore fewer witnesses and more in one go with cuts. Also, the increased specific populations identified is found in mixed stands, primarily in old mixed stands, followed by the young. In pure stands, the number of populations is somewhat lower, this is explained by the fact that mixed stands show greater variability of species, both trees and shrubs, especially grasses, making them more stable in time, giving them thus sustainability and variability. Abundance in specific populations

Abundance is a structural indicator, quantitative evaluation, the number of individuals of each specific population, in the phytocoenoses. This indicator was calculated based on primary data, collected from the field, for each layer of phytocenosis and to stand as a whole.When analyzing pairs of variants covered with two types of work, rarerly and progressive cuts, we can observe an increasing trend of the variation coefficient with increasing number of species especially progressive variants covered with cuts, where the number of species identified is moreDensity and species frequency

To determine the density were taken into account absolutely all species identified in each sample area, the number of individuals of each species per hectare was reported and the frequency (in her case was considered only herbaceous and shrub layers) was calculated by the coefficient of variation of frequency.

Specific diversity - Shannon-Wiener diversity index (H s)

He watched how the Shannon-Wiener index variation (H s) to specify the number of species diversity for all stands to witness variants compared rarerly traveled, progressive cuts respectively.Features on floristic diversity

As the minimum area determined, we can say that it has different sizes, depending on the type of stand taken for investigation,In the 24 areas of research and 48 variants (control and covered with cuts), we identified 261 species of vascular plants, the number of species is low in control stands (110), in which anthropogenic interference was lower, higher number (216) being driven with the cuts (rarerly, that gradually cuts). If we refer to each type of brush in hand, we can say that, of all species identified, 17 are tree species, 18 species and 226 shrub species are herbaceous. For the abundance analysis, we used the coefficient of variation of abundance (and% a), which increases with increasing number of species, but completely different for each layer of vegetation in part. A more marked increase is found in the herbaceous layer, shrub layer scaled to, and the lowest growth occurs in the layer tree, explaining that the number of species, which decrease the herbaceous layer to the tree.

Frequency was analyzed only in the herbaceous and shrub layers as tree layer contains a few trees. There is also the trend of increase of the coefficient of variation of frequency with increasing number of species. As the index Shannon - Wiener, was also analyzed in relation to the number of specific populations identified. Just as the other indices studied, and values of this index increases with increase in specific populations In group variations on types of trees, pure (young and old) and mixed (young and old), there is increasing diversity in mixed stands, and especially the old, where the number of species identified is greater .Indicators of tree layer diversity

In this paper we refer to the tree layer diversity, diversity presented both in general, the mountain and the seat is calculated in the base area of each type of stand studied (pure beech and beech trees mixed with resin , young and old), with control options and covered with papers.

Composition of tree layer

Tree layer composition calculated using the base areaTree layer composition was calculated as a percentage, depending on the base area for each species that forms.By analyzing the composition of the studied stands, we can say that a large proportion is occupied by three species, namely - beech, fir and spruce. With much lower participation, may appear hornbeam, mountain maple. A higher percentage plays beech, followed by pine and spruce.Indicators of horizontal and vertical structure

Were used distribution models the number of tree diameter categories, namely categories of heights.Influence of horizontal structure on specific diversity

Horizontal structure to represent the influence of specific diversity was used as a measure of diversity, coefficient of variation of diameters by the number of species identified in each type of stand taken studiu.De also higher values of the coefficient of variation of diameters meet in the trees rather multi-year, compared to the relatively echienes.The influence of vertical structure on specific diversity

As the analysis of horizontal structure, and the vertical structure, have been using the same indicators of specific diversity, have been considered specific diversity index. Graphic representation of how the variation of the number of species according to the coefficient of variation of heights, you can feel great similarity between the number of species variation and the coefficient plot variation of diameters, this is normal given the very close correlation between the diameters and heights, but of course, and the coefficients of variation of the two sizes.Features of structural diversity

In the pure beech forests, the dominant species is the beech, the proportion of 93% in young beech, version control, that 99% traveled to work options. If old pure beech forests, beech proportion is 93%, for both, witnessed and covered with papers. You must mention that, besides beech as dominant species in very low proportions meet and spruce, fir, with percentages ranging from 2% to 5%. In the young beech trees, which are mixed with resin, that is all beech dominant species, but slightly lower proportions 59% (for many consumers variants) and 63% (for variants covered with cuts), and the old trees the proportion is slightly lower 51% (for control variants) and 49% (for variants covered with cuts). We note that the dominant species, beech, is followed in rather low proportions of larch, pine, mountain maple, alder, aspen, linden, hornbeam.If the diameter class distribution of trees, there was a large structural diversity of stands, there stands the relatively echiene and relatively multi-year, present the alternatives considered are both blank and completed within the cutting. To calculate the relative frequency of trees, Shannon-Wiener index was used, the horizontal structure diversity that the number of trees, was found lower horizontal structural diversity (with fewer trees). If we look at movement in the index in relation to the base area, shows the same decrease in diversity with increasing intensity of the draw, so the lower base area, the correlation is more apparent in trees covered with cuts, due to lower variability of diameter classes . In terms of vertical structure, we can say that there is a strong resemblance to the horizontal, but in this case we refer to the number of tree heights distribution.If categories relate how the variation of vertical structure diversity index based on relative frequency of trees class of heights, with changing the number of trees, there is vertical structure diversity decreased with decreasing number of trees, thus decreasing diversity with decreasing vertical struturii number of trees, is caused by reduction of the high variability classes. If we analyze the Shannon-Wiener index variation of vertical structure, the relative size of the base area, it may be noted that vertical structural diversity decreases with the base area, but the coefficient of variation of height increases with decreasing base area due harvesting trees of medium height categories, such as rriturilor, but for progressive cuts, falls from height variability collection of absolutely all kinds of tree heights, including the most extreme.Silvicultural interventions influence the diversity of primary producers

Silvicultural works carried out in two types of trees, pure beech (young and old), respectively, in mixed stands of beech with pine (young and old) cuttings are the rarerly and the progressive cuts.In terms of progressive cuts, they were both executed in the old pure stands and in mixture with pine. In these types of trees, in terms of composition, dominant species is the beech, followed by fir, pine, spruce, larch, hornbeam, aspen, alder, all in small proportions.Also be noted that, at these trees, whose structures are very different, from relatively echienes until relatively multi-year, with different degrees of canopy closure, due to progressive cuts, the number of species identified is higher, unless of the rarerly cuts. It is known that through these types of cuts, harvested trees unevenly and in a larger number, grouped, which allows light to penetrate into a higher ground level, the mesh formed, allowing thus developing a greater num species both herbaceous and shrub.

Indicators used to characterize specific diversity are the spread in abundance - and% the coefficient of variation of frequency - and% f and specific diversity index Shannon-Wiener - H's). Generally, these indicators of specific diversity, which have been calculated, have a tendency, just as discussed, increase with increasing number of species, however, appear deviations from this situation, for example, the coefficient of abundance variation (s% a) stands covered with cuts and specific diversity index (H s) in tree layer decreases with increasing number of species. The tree layer, specific diversity decreases due to harvest the trees, leading to species extinction in this layer. Also, the values calculated, the ratios, and also show that were not strictly observed the technical application of silvicultural work, they are made, sometimes superficial, intensity interventions at odds with the protocols for these technologies, and mixtures were not always done best, explaining thus the presence of a higher number of species in certain amenajistics units. If we analyze the influence of horizontal structure of specific diversity, using the base area of the stand (Gr), there is specific diversity decreased with decreasing base area. Treatment of progressive cuts into account the dynamics of regeneration and harvesting trees is based on seedling growth. As the seedling grows, shades the soil and herbaceous species limited installed, competing, in fact and shrubs. The base area of the stand can be even greater than when the first intervention, as a result of activation increases in diameter (Avcriei, 2005). Consequently, there is either a strong development of seedlings, other plant species that prevent installation or there is a specific increase in diversity with increasing base area, a different case, one can represent also the herbaceous layer destruction, bush, and installed after the last cutting of seedlings, at a new mine, or for enlarging holes or for connection. In terms of a horizontal structure was used as an indicator of the spread in diameter and it was concluded that regression takes place in reverse, which means that species diversity increases with decreasing of diameters variation.It result that spread in the diameter decreases , thanks to the number of urge extraction a smaller tree, of medium diameter classes, resulting in thinning stands that by the amount of light reaching ground level, is more intense. In terms of vertical structure, there is a slight increase in specific diversity or the number of species with decreasing coefficient of variation of heights.The influence of structure on specific diversity manifests it self indirectly through seedlings. Growth coefficients of variation of diameter and height, increase the surface occupied by seedlings, affecting the development herbaceous and shrub layers. Regarding the rarerly cuts, they were made only in the young trees (beech and pure beech stands mixed with resin). In these types of trees, their structure differs in that it is both relatively echienes and relatively multi-year. In terms of composition, we can say that the beech, which is the dominant species, is a much higher percentage, especially in pure beech, as we mentioned in section anteriror. In the pure beech forests may appear in a lower percentage fir, spruce and mixed stands in may occur with these two species and hornbeam, poplar tree, alder, larch. As shown, specific diversity indicators tend to increase with increasing number of species, but there appear deviations from this situation, for example, the spread in abundance (s% a) the stands covered with cuts, and and index of specific diversity (H s) in layer tree decrease as the number of species, but it should be noted that following of rarerly cuts, draw a relatively small number of trees that uniform, so that the number of species that are installed, is more reduced compared with cuts taken progressive stands. The tree layer, decreases specific diversity here, but slightly, following the harvesting of trees, leading to the extinction of species in tree layer.f we analyze the influence of horizontal structure of specific diversity, using the base area of the stand (Gr), there is also specific diversity decreased with decreasing base area, as in the previous case, and if used as an indicator of horizontal structure coefficient of variation of diameters and specific aims diversity index (H s) or number of identified species, species diversity increases with decreasing diameter variation, but in a narrower sense.General conclusions:

Following research and results in forest ecosystems Ciucas, we draw the following conclusions, namely:- In terms of diversity of primary producers- The species richness is greater in stands covered with progressive cuts, where they found 180 species (beech stands in old mixed with resin, namely pure beech), and is lower in stands covered with rrituri, where the number species is lower, about 81 (young beech stands in mixture with pine, beech that young).- The analysis of abundance variability was found to increase with increasing number of species, but different for each layer of vegetation, respectively for each type of cutting.- In terms of frequency of species, correlation coefficients are higher for herbaceous layer, and have values close to the trees that are mixed with resin, which is normal, if we consider that the number of grass species for these types of stands, is higher.- The analysis of the Shannon-Wiener index of specific diversity that, both herbaceous and shrub layers, either considered separately, the two alternatives "witness" and "covered with cuts" are made on the two layers of vegetation diversity index increases with increasing number of species.In terms of horizontal and vertical structures of the sub tree

-The pure beech forests, dominant species, beech, who is in a proportion of 93-99%, and the present species as fir, spruce, but in very low proportions 2-5%.In the beech-trees, which are mixed with pine, beech dominant species is all but a slightly lower proportion of 49-63%, this being due to the presence of other species, in different proportions: hornbeam, maple mountain , oak, maple, elm, ash, field maple, white alder.In terms of influence stand structure subject to two types of silvicultural interventions on the diversity of primary producers

- For stands covered with rarerly cuts, specific diversity (H s) is an increasing trend as the base area decreases.- Taking into account the spread in diameter, as an indicator of horizontal structure, and specific diversity or Follow the variation in species richness, the same dependence is found, the latter increase as the diversity decreases horizontal structure.- The influence of vertical structure on specific diversity, manifested in a similar horizontal structure.

Recommendations for production

-To avoid damage and degradation that occur in intervention techniques and exploitation of timber.- The application of such interventions lead to the increase structural diversity of tree layer and the appearance and preservation of a greater number of primary producers in other phytocenotics layers ecosystem.- Apply operating environmental measures adapted to the particular conditions of each operating unit, depending on the orography of state land and seedlings, to ensure natural regeneration and biodiversity conservation.

Personal contributions

Contributions of personal, original character, remember the following:

- Were investigated and structural diversity that characterizes the first time represented by beech forest ecosystems and in the beech mixed with resinnons, the Ciucas Massif;- To weigh the influence of rarerly and progressive cuts applied in the study area, the specific diversity of primary producers;- Was established in species richness, abundance, density, frequency and specific diversity, the indicators renowned for the region taken in research;- Were studied, biodiversity indicators, compared, for both research taken for each intervention separately, and each layer fitocenotic, analyzed separately;PAGE 11