Colonisation ecology of forest-dwelling vascular plants and the conservation value of rural manor parks
Date
2014-10-17
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Metsade pikaajaline ja intensiivne kasutamine on oluliselt vähendanud elurikkusele tähtsa biotoobi pindala ja halvendanud ökosüsteemi looduslikku seisundit. Isegi Eestis, kus metsamaa osakaal on viimase sajandiga kasvanud ja katab nüüdseks umbes poole maismaast, on metsaelupaikade kvaliteet jätkuvalt halvenenud. Seepärast on oluline toetada metsade elurikkuse kiiret taastumist uudistekkelistes metsades. Maapiirkondade mõisapargid pakuvad ainulaadset mudelsüsteemi uurimaks metsaliikide pikaajalist levikuökoloogiat. Käesoleva doktoritöö eesmärgiks oli tuvastada tegurid, mis mõjutavad metsaliikide asustamist uutes kasvukohtades ning hinnata mõisaparkide ökoloogilist väärtust metsaelurikkuse seisukohast.
Doktoritöö tulemused viitavad, et vanad mõisapargid suudavad anda olulise panuse metsade elurikkuse säilitamisse. Parkide varjulistes osades leidus palju salumetsadele iseloomulikke taimeliike ja neid toetavaid vanametsadele omaseid struktuure, mida tänapäeva raieküpsetes metsades kohtab harva. Lisaks selgus, et metsataimed suudavad edukalt asustada uusi elupaiku, kui anda neile piisavalt aega, sobivad maastikutingimused ja elupaigakvaliteet. Maastiku tasemel on määravaks piisavas koguses liikide levikuallikateks sobivate metsade olemasolu ja omavaheline ühendatus. Elupaiga tingimustena tuleb eelkõige tagada puistu piisav suurus ja keskmiselt varjulised tingimused. Seejuures on lisaks puuvõrade liitvusele oluline ka mõningane põõsaste ja järelkasvu olemasolu. Metsaspetsiifilised liigid eristusid levikukoridore ja avamaastikke kasutada suutvatest liikidest paindliku paljunemis- ja levimisstrateegia poolest ning olid madalama kasvu ja väiksema mullatoitelisuse nõudlusega. Ühtlasi selgus, et metsataimede omadustest olid limiteerivamateks just asustamisega seotud taimetunnused.
Mõisaparkide mitmekülgseks väärtustamiseks peaks nende kaugemaid varjulisi osi kujundama ja hooldama looduslähedaselt, keskendudes laialeheliste metsade tingimuste jäljendamisele. Elurikkuse kujunemise toetamisel uutes metsades on tähtis mitmekesise puistustruktuuri loomine ja selle pikaajaline säilitamine, mistõttu tuleks ka parkides säilitada liigirikas puistu- ja põõsarinne ning pargi kaugemates osades ka üksikud vigastatud puud. Toetamaks metsaomaste liikide edenemist parkides, tuleks hilisemate õitsejate soodustamiseks vältida varjuliste pargialade varajast niitmist.
Forests are among the most-threatened ecosystems in Europe. Severe human impact has reduced forest cover and decreased the habitat quality in remaining stands. Even in Estonia—where forests cover about half of the country—habitat quality is often diminished. Throughout history a large number of rural manor parks have been established across Estonia. The landscape setting and history of these parks make for a unique study system to disentangle the colonisation ecology of forest species. Therefore, the aim of this thesis was to identify factors affecting colonisation ecology of forest-dwelling species and the ecological value of old rural manor parks. This thesis shows that old rural manor parks can contribute to forest biodiversity. Especially the closed-canopy parts of parks harbour forest specific species and stand characteristics typical to old-growth nemoral forests. Many of these habitat properties are rare in contemporary mature forests. The results also show that forest species are able to colonise forest-like habitats when given enough time, a suitable landscape setting and favourable habitat conditions. At a landscape level this means ensuring the availability of species source habitats and supporting habitat connectivity. A favourable habitat is sufficiently large in size and has limited light conditions suitable for forest species. In addition to the sufficient closure of the tree canopy layer, it is important to have some shading by shrub and lower tree layers. Plant species that were successful in colonising park habitats were adapted to tolerate shade and flowered early in the growing season, but also had a higher requirement for soil nutrient and higher values for a ruderal life strategy. To support forest specialist species in parks, park management levels needs to be kept moderate or aim at mimicking broad-leaved forest conditions. Therefore it is important to support a diverse stand structure by retaining old or damaged trees and by avoiding early-season mowing.
Forests are among the most-threatened ecosystems in Europe. Severe human impact has reduced forest cover and decreased the habitat quality in remaining stands. Even in Estonia—where forests cover about half of the country—habitat quality is often diminished. Throughout history a large number of rural manor parks have been established across Estonia. The landscape setting and history of these parks make for a unique study system to disentangle the colonisation ecology of forest species. Therefore, the aim of this thesis was to identify factors affecting colonisation ecology of forest-dwelling species and the ecological value of old rural manor parks. This thesis shows that old rural manor parks can contribute to forest biodiversity. Especially the closed-canopy parts of parks harbour forest specific species and stand characteristics typical to old-growth nemoral forests. Many of these habitat properties are rare in contemporary mature forests. The results also show that forest species are able to colonise forest-like habitats when given enough time, a suitable landscape setting and favourable habitat conditions. At a landscape level this means ensuring the availability of species source habitats and supporting habitat connectivity. A favourable habitat is sufficiently large in size and has limited light conditions suitable for forest species. In addition to the sufficient closure of the tree canopy layer, it is important to have some shading by shrub and lower tree layers. Plant species that were successful in colonising park habitats were adapted to tolerate shade and flowered early in the growing season, but also had a higher requirement for soil nutrient and higher values for a ruderal life strategy. To support forest specialist species in parks, park management levels needs to be kept moderate or aim at mimicking broad-leaved forest conditions. Therefore it is important to support a diverse stand structure by retaining old or damaged trees and by avoiding early-season mowing.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
metsataimestik, levik (biol.), pargid, mõisad, bioloogiline mitmekesisus, forest flora, distribution (biology), parks, manors, biodiversity