Course info

Stațiuni forestiere

În concepţia colectivului (Chiriţă, Vlad, Păunescu, Pătrăşcoiu, Roşu şi Iancu, 1977), staţiunea, ca loc de viaţă a unei biocenoze, este pe de o parte o unitate fizico-geografică, o unitate elementară (geotop) a landşaftului sau peisajului. Dar în acelaşi timp este şi o unitate ecologică (ecotop) prin regimurile de lumină, căldură, umiditatea aerului şi a solului, a ionilor din sol proprii acestei unităţi. Ca unitate fizico-geografică, staţiunea se caracterizează prin aşezare geografică care îi defineşte clima, prin relief, substrat pedogenetic şi sol. Ca unitate ecologică se caracterizeazăprin specificul regimurilor factorilor ecologici enumeraţi. Staţiunea are deci  elemente mai mult sau mai puţin stabile - cele fizico-geografice şi elementele variabile în timp - regimurile factorilor ecologici.

Potenţialul productiv se stabileşte după categoria de productivitate a speciei de arbori

(productivitate superioară - clasa I şi II de producţie, productivitate mijlocie - clasa III de

producţie, productivitate inferioară - clasa IV şi V de producţie). Regimurile trofic şi hidric a solului se stabilesc după tipul de floră ierboasă indicatoare.

Până în prezent au fost descrise peste 200 de tipuri de staţiuni. De exemplu, în etajul

montan de molidişuri au fost diferenţiate 28 de tipuri de staţiune.

Petrică Tudor MOŢIU. Cercetări asupra tipurilor de ecosisteme forestiere de pe ultimele prelungiri vestice ale masivului pădurea craiului în vederea stabilirii măsurilor de gospodărire durabile. Rezumatul tezei de doctorat. Universitatea „Transilvania” din Brașov, 2013. 101 p.

Pădurile cuprind formații vegetale extrem de complexe si de diverse, așezate in mai multe straturi, ca si fauna si flora pe care le găzduiesc. Putem descoperi mai multe biomuri forestiere si anume: păduri din zona temperata cu foi caduce, păduri taiga, pădurile cu frunze persistente de tip mediteraneean si păduri dense ecuatoriale care sunt cel mai bine reprezentate in bazinul amazonian, in Africa tropicala, in Indonezia si in Malaiezia.

Privita in ansamblu, contribuția pădurii la menținerea echilibrelor in biosfera prezinta o importanță, deosebita fie sub forma de masiv, fie ca perdele de protecție. Din aceasta cauza, exploatarea pădurilor, la nivel mondial sau național, trebuie raționalizata nu numai ca volum lemnos, dar si ca metode folosite pentru a se evita, pe cat posibil, reducerea fondului forestier. Creșterea suprafețelor de teren agricol, nu mai este posibil a se realiza pe seama micșorării suprafeței de păduri, ba dimpotrivă, cel puțin la noi în țara, in multe zone se impune împădurirea unor terenuri neproductive.

Datorita defrișărilor exagerate și distrugerii pădurilor prin exploatări neraționale si a pășunatului excesiv, la nivel mondial, a luat proporții îngrijorătoare fenomenul de deșertificare, evident mai ales pe continentul African, unde daunele produse pădurii nu pot fi justificate ecologic si nici economic prin pășunatul fondului silvic.

In acțiunea distructiva a fondului forestier, un rol însemnat îl are si poluarea aerului, care produce fenomenul de uscare al arborilor. In Europa, de exemplu, pe aproximativ 10 milioane hectare de pădure, s-a semnalat uscarea arborilor de molid, brad, stejar si gorun, iar in tara noastră, asemenea fenomen a afectat 1,6 % din suprafața totala a pădurilor. La uscarea arborilor a mai contribuit, de asemenea, poluarea de mare altitudine, cat si cea produsa de industriile chimica si petroliera, de fabricile de ciment, combinatele metalurgice si miniere.

Privite in ansamblu, importanta pădurii si menținerea echilibrului ecologic si acțiunile distructive la care aceasta este supusa, se poate ușor desprinde necesitatea colaborării pe diverse planuri a tuturor specialiștilor care activează in diferite sectoare productive si de cercetare ale agriculturii si silviculturii, in scopul refacerii si menținerii echilibrelor ecologice, atât de importante vieții de pe Terra.

Stațiunea forestieră sau biotopul reprezintă:

• locul de viață al biocenozei
• componenta sau subsistemul de natură anorganică
• mediul fizic al ecosistemului

Biotopul este alcătuită din:

• elemente ale reliefului
• elemente ale rocii sau materialului parental
• elemente ale solului

Aceste elemente constituie fondul climatic și edafic de substanță și energie al biocenozei. Stațiunea forestieră asigură spațiul aerian și subteran. Producția și productivitatea ecosistemelor forestiere sunt influențate de gradul de favorabilitate al stațiunii. Stațiunea forestieră este componenta cea mai stabilă a ecosistemului. Trebuie cunoscute aptitudinile fitocenotice ale stațiunii. Stațiunea forestieră este un subsistem integrat al pădurii:

• biotopul = spațiul mărginit de limitele ecosistemului = micro mediu
• mediul ambiant (dinafara limitelor ecosistemului) = macro mediu; el influențează prin energia radiantă, precipitații, mișcarea aerului, etc;

Stațiunea ca sistem (elemente componente). Ca orice sistem, stațiunea e definită prin:

1. elemente componente
2. conexiuni dintre ele
3. stări

1. Elementele componente (relief, rocă, sol, climă) dau stațiunii caracter de:

a)      unitate fizico-geografică (geotop)

b)      unitate ecologică

a) Ca unitate fizico-geografică , ea reprezintă un areal limitat caracterizat prin următoarele elemente:

• Situația (așezarea geografică) – latitudine, longitudine, altitudine
• unitate mare de relief (geomorfologică) și forma de relief (câmpie, platou, versant: în cazul lor: expoziție, pantă, poziția)
• roca și substratul litologic (sedimente moi, depozite de dezagregare)
• învelișul de sol: profunzime, orizonturi.

Prof. univ. dr. Alda Simion. Componentele stațiunii forestiere.

https://biblioteca.regielive.ro/proiecte/agronomie/componentele-statiunii-forestiere-246872.html

Station forestière

Une « station forestière » est une étendue de terrain de superficie variable (quelques mètres carrés à plusieurs dizaines d'hectares), homogène dans ses conditions physiques et biologiques : mésoclimat, topographie, géomorphologie, sol, composition floristique et structure de la végétation spontanée.

Le gestionnaire forestier et le sylviculteur peuvent utilement identifier chaque station car ses caractéristiques géomorphologique, géologique ou pédologique, ainsi qu'écologiques (dites « stationnelles ») vont plus ou moins y contraindre la flore et la faune, et moduler leur résilience face aux actions de gestion sylvicole ou à des événements de type incendie, tempêtes, chablis.

Forest sites

Occasionally, you may hear foresters use the term “habitat type” while describing a piece of ground and strategizing how to manage it. This term does not refer to wildlife habitat, though the system can be used to describe wildlife habitat. Habitat types are a land classification system based on the patterns and trends of how trees and other plants grow on the landscape.

Site classification based on succession. Habitat types are intimately tied to the concept of succession -the changes in the mix of plant, animal, and fungi species over time, barring disturbance. Forest succession starts after a major disturbance, after which shade intolerant species such as pines or larch dominate the site. Over time, shade tolerant species become more prominent. This process culminates (barring more disturbance) with a climax forest, dominated in the overstory and the understory by the most shade tolerant species capable of growing on the site.

The climax plants and trees reveal the site. Successionfollows different paths, depending on a  site’s moisture, soil, and other factors. Habitat types are based on the idea that on a given site, the same successional patterns will repeat after disturbances and that the climax forest plants and trees are a meaningful index of soils, topography, precipitation, and other factors affecting the growth of trees and other organisms there.

In some regions, similar site classification systems are also known as “plant associations”, though there are some differences between systems (e.g., some systems integrate topography, soils, and other features more directly). In northern Idaho, eastern Washington, and western Montana, habitat types are the rule.

How can habitat types be used. Habitat types can help you understand successional pathways on your property and make forestry decisions. Knowing the habitat type gives you some clues as to which species to favor. For example, white pine probably occurred on a hemlock habitat type historically, even if you can’t find any white pine on the site. By contrast, western red cedar probably never occurred on a site with a Douglas-fir habitat type in the last few thousand years.

Habitat types can also provide management insights, depending on how much data has been collected for the type. For example, if you are likely to get a heavy stand of brush species after disturbance for a given habitat type, it may be worth buying larger seedlings that will beat the brush to occupying the site. You can also get site productivity information, whether you are looking for board feet, animal unit months, or huckleberries. One recent forestry shortcourse participant decided she wanted to buy forest property in a hemlock habitat type because of their relatively high productivity.

Perhaps the chief benefit of learning about habitat types is how it affects the way you think about your forest. If you endeavor to do as Aldo Leopold suggested and “think like a mountain”, a good understanding of habitat types provides a valuable part of the vocabulary for that effort, and will provide many insights along way. Chris Schnepf. Forest Habitat Types: A Plant-Based Clue to Better Forestry. UI Extension Forestry Information Series. University of Idaho. Forest Management No. 34. 3 p.

Surse: https://www.google.com/search?q=Forest+site+classification

Soil quality is the most important factor in forest management decisions. Soils will determine which tree species yield the greatest timber volume, the time to harvest, and ultimately, the investment a landowner must make to yield an acceptable economic return from forest management.

Soils vary greatly in their ability to produce merchantable volumes of pulpwood, sawtimber, veneer, poles, piling or other wood products in a reasonable period of time. The old saying "plant your sorry, worn-out acres to trees" has been followed by many an unwary landowner. In fact, as with any other crop, the better the land, the more productive the forest. Landowners must be aware of soil factors that affect forest production before investing in forest regeneration or management.

Site Index (SI). The collective influence of soil factors will determine the site index for a particular tree species on a given soil area. Site index is the total height to which dominant trees of a given species will grow on a given site at some index age, usually 25 or 50 years in the Southeast. Dominant trees are the tallest trees in the stand. If it is stated that an area has a site index for loblolly pine of 70 feet at 50 years, then we expect loblolly seedlings planted on that area today to be 70 feet tall in 50 years. Index age and tree species must be stated when referring to site index because the site index of one species will be different from the site index of another species growing on the same area. There is a close relationship between site index and timber yield. Volumes of merchantable wood increase with improvement in site index.

Soil Factors. The following factors have a major impact on forest soil productivity and site index:

• Topsoil Depth. The depth of the uppermost soil layer is a critical factor affecting tree growth. Topsoil is highest in organic matter and nutrients, is usually well aerated and drained, and allows maximum root growth and root penetration.
• Soil Texture. The proportion of sand, silt, and clay in the topsoil and subsoil layers is called texture. Sandy soils are normally very well drained and often lack nutrients due to constant leaching loss. At the other end of the spectrum are the pure clay soils comprised of very small, fine soil particles.
• Subsoil Consistence Class. Consistency of the subsoil layer is another important factor in forest soil productivity. The combination of soil-sized particles and the physical and chemical properties of each individual particle type in a given soil determine the soil's consistence class.
• Limiting Layers. A layer which restricts the downward penetration of a tree's root system will reduce tree growth in direct relation to the depth of layer. In rare instances, a limiting layer may increase site productivity, such as on sandy soils where the layer may retard leaching of nutrients and increase available moisture.
• Fertility. Southern pines grow over a wide range of soil fertility levels. Fertilization is normally not recommended early in the rotation except in the case of a critical deficiency of a major nutrient such as phosphorus. A soil test prior to site preparation will alert a landowner to critical deficiencies. Research has shown conflicting results in forest tree response to nitrogen fertilization, particularly early in the rotation. Growth may be suppressed if the fertilizer increases the growth of competing weeds. Best results from early fertilizer use arise in combination with herbicide or mechanical control of competing vegetation. Late rotation fertilization done five to eight years before final harvest increase timber yields in many situations, but may not be economically practical.
• Internal Drainage. Few tree species can grow in soils which are constantly wet. Drainage can be improved in some cases by tilling, ditching or adding bedding as a site preparation method.

Species Selection. Selecting the proper tree species to manage or plant on a particular site involves several steps.

• Determine objectives. If timber production is the major objective, select a species that will economically produce timber products. If wildlife, recreation, aesthetics or other uses are the objective, select species accordingly. On many tracts, several uses may be compatible.
• Select species with a proven track record in terms of growth and acceptance in the local market.
• If two or more species could be selected and timber production is the major objective, select the species that will yield the greatest dollar return in the shortest amount of time. In most cases, this means selecting the species with the highest site index.

Landowners should invest only in those species on those acres capable of producing acceptable economic return. Returns will vary with investment, species, and site quality. Foresters can provide information including site quality, yield, and projected economic returns before deciding which, if any, species should be managed on a particular property.

Rick Hamilton. Department Extension Leader – Specialist Forestry & Environmental Resources. Forest Soils and Site Index Woodland Owner Notes. Publication date: March 1, 2019 WON-07. https://content.ces.ncsu.edu/forest-soils-and-site-index

Типы лесорастительных условий

Тип леса — участок леса или их совокупность, характеризующиеся общим типом лесорастительных условий, одинаковым составом древесных пород, количеством ярусов, аналогичной фауной, требующие одних и тех же лесохозяйственных мероприятий при равных экономических условиях (определение В. Н. Сукачёва). Коренные типы леса развиваются в природе без влияния человека или природных катастроф. Производные типы леса сменяют коренные в результате воздействия этих факторов. Коренной и одноимённые производные типы образуют серию типов леса.

На практике понятие типа леса часто подменяется понятием типа лесорастительный условий (типа условий местопроизрастания), то есть совокупности однородных лесорастительных условий на покрытых и не покрытых лесом участках. Очевидно, что тип лесорастительных условий — понятие более широкое, нежели тип леса. Типы лесорастительных условий устанавливаются по растениям-индикаторам эдафических условий (школа В. Н. Сукачёва) или по показателям богатства и влажности почвы (украинская школа).

Идея о связи леса и условий его произрастания отмечалась крестьянами ещё до развития научного лесоводства. В первых лесоводственных работах широко использовалась местная народная терминология:

Необходимо умение сразу смотреть и на лес, и на занятую им среду; такое обобщение давно уже живёт в вековой мудрости народа, крылатыми словами отметившего совокупность и территории, и его лесного населения, степень их соответствия друг другу в таких терминах, как рамень, сурамень, суборь, согра и т. д. <…> Дело науки точнее проанализировать и выделить ту совокупность условий, которую создаёт рамень, сурамень, суборь <…>. —Г.Ф. Морозов, 1917

Лесная типология за рубежом. На методы классифицирования лесов в зарубежных странах оказали существенное влияние идеи Г. Ф. Морозова и В. Н. Сукачёва.

В основе лесной типологии зарубежных стран могут находиться как типы леса, так и типы лесорастительных условий. Первое более типично для многолесных стран, в которых сохранилось относительно много лесов естественного происхождения (классификация Каяндера в Финляндии). Классификация по типам лесорастительных условий более характерна для стран с преобладанием искусственно созданных насаждений и высокой интенсивностью лесного хозяйства (Польша, Венгрия, Румыния). Возможно и сочетание этих принципов (Англия).

Разнообразие конкретных методик классификации и периодическая их смена не способствуют полноценному учёту географического районирования. Однако, в ряде стран (Франция, Германия, США) географические особенности учитываются при выделении типов леса.

В некоторых странах (Австралия, Австрия) во внимание принимается история развития древостоев.

Свои особенности имеет классификация горных лесов. Обычно при выделении типов во внимание высотная поясность, экспозиция склона, направление господствующих ветров. Кроме того, в некоторых странах могут использоваться и дополнительные признаки (глубина снежного покрова, индекс холода, средний прирост древостоя и т. д.).

Практическое значение лесной типологии

Наиболее очевидная хозяйственная функция лесной типологии — оценка количества и качества древесных ресурсов. Известно, что с типом леса связан бонитет, который является оценкой продуктивности древостоя. Кроме продуктивности, выражаемой в объёме древесины, получаемой с единицы площади, тип леса характеризует также сортиментный состав и качество древесины. Столь же очевидно влияние леса и на продукты побочного пользования.

Тип леса (тип лесорастительных условий) необходимо учитывать и при планировании лесохозяйственных мероприятий: планировании рубок, выборе способа очистки лесосек, проектировании содействия естественному возобновлению или лесокультурных работ и т. д.

С типом леса связана устойчивость его к различным неблагоприятным воздействиям: болезням, вредителям, пожарам, ветровалу и другим. Соответственно, при планировании лесозащитных работ и работ по охране леса от пожаров необходимо учитывать тип леса.

ru.wikipedia.org/wiki/Тип_леса