Urban Ecology - Why Is It an Increasingly Important Topic? / Urbana ekologija – zakaj se njen pomen povečuje?

author: Heikki Setälä, University of Helsinki
published: Nov. 9, 2009,   recorded: October 2009,   views: 269
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Land-use changes due rapidly increasing urbanization pose major threat on ecosystems and their functions worldwide. By the end of this decade, more than half of the world human population will be living in cities and other urbanized areas. Human-induced habitats, loss and fragmentation of the landscape as well as accumulation of trace gases and other pollutants serve as the best-known examples of negative impacts of dense human population on the surrounding environment. Land-use changes can be seen analogous to soil use, as well-developed old soils are replaced by functionally altered soils or even by completely new substrates, called “made lands”. Such conversion of land and soils to urban use is likely to translate into changes in soil biota, thereby distorting life-supporting ecosystem services, such as decomposition of organic matter, cycling of nutrients and detoxification of harmful substances. Urban soils are traditionally described as being highly artificial and disturbed, although soils in urban parks and gardens can share many features typical to agricultural, even natural soils. One of the key factors distinguishing urban soils from natural soils is their high spatial heterogeneity in the various ecological patterns and processes. This high heterogeneity manifests as parks, cemeteries, vacant lots, streams and lakes, gardens and yards, campus areas, golf courses, bridges, air ports and landfills. These habitats are highly dynamic, influenced by both biophysical and ecological drivers on the one hand and social and economic drivers on the other. Active management of green spaces is vital but seldom sufficient, there is also a need to protect, restore and manage surrounding ecosystems in order to maintain ecosystem services of value for human well-being and build resilience in the urban landscape. Recent climate models predict precipitation to increase under various climatic conditions, especially in heavily urbanized areas. Combined with increasing proportion of sealed, impermeable surfaces in urban settings, the growing trend of rain events are likely to cause anomalies in hydrological cycles. A typical example of it is the increased quantity and worsened quality of urban runoff waters (“street waters”). In this presentation urban runoff waters will be dealt as an indicator of the ecological health of urbanized habitats. Furthermore, the typicalities of urban vs. natural ecosystems are compared and some examples of the ongoing urban ecological studies in Finland will be presented.


Zaradi hitro naraščajoče urbanizacije prihaja do sprememb v rabi zemljišč, kar predstavlja pomembno grožnjo ekosistemom in njihovemu delovanju širom po svetu. Do konca tega desetletja bo več kot polovica svetovne populacije živela v mestih in drugih urbaniziranih območjih. Habitati, ki jih spreminja človek, izguba in fragmentacija pokrajine kot tudi sproščanje plinov v sledovih in drugih onesnaževalcev služijo kot najbolj znani primeri negativnih vplivov goste človeške populacije na okolje. Spremembe v rabi zemljišč lahko gledamo kot izrabo tal, ko se dobro razvita stara prst nadomešča s funkcionalno spremenjeno prstjo ali celo s povsem novim substratom, tako imenovano "umetno zemljo". Takšno spreminjanje zemljišč za potrebe urbane uporabe najverjetneje vodi v spremembe v življenju v prsti in tako poruši življenjske podporne mehanizme ekosistema, kot so razgradnja organskih snovi, kroženje hranil in razstrupljanje škodljivih snovi. Zemljo v urbanih območjih po navadi opisujejo kot umetno in močno prizadeto, vendar pa je prst v mestnih parkih in vrtovih lahko zelo podobna kmetijski ali celo naravni prsti. Eden glavnih dejavnikov, po katerih se zemlja v mestih loči od tiste v naravi zunaj mest, je velika prostorska heterogenost različnih ekoloških vzorcev in procesov. Visoko heterogenost kažejo okolja kot so parki, pokopališča, gradbišča, potoki in jezera, vrtovi in dvorišča, univerzitetna naselja, igrišča za golf, mostovi, letališča in smetišča. Ti habitati so zelo dinamični, nanje po eni strani vplivajo biofizikalni in ekološki dejavniki, po drugi strani pa socialne in ekonomske težnje. Aktivno upravljanje zelenih prostorov je zelo pomembno, vendar redko zadostuje; treba je ščititi, obnavljati in upravljati tudi okolišnje ekosisteme, zato da se vzdržujejo podporne storitve v ekosistemih, ki so pomembne za blagostanje ljudi in omogočajo prožnost urbane krajine. Zadnji klimatski modeli napovedujejo povečanje količine padavin v različnih klimatskih pogojih, še posebno v močno urbaniziranih območjih. V povezavi z vedno večjim deležem zatesnjenih, neprepustnih površin v urbanih okoljih je zelo verjetno, da bo naraščajoči trend dežja povzročil anomalije v hidroloških ciklih. Tipični primer tega je povečana količina in poslabšana kakovost urbanih površinsko odtekajočih voda ("ulične vode"). V tej predstavitvi bodo urbane odtočne vode uporabljene kot kazalnik ekološkega zdravja urbanih življenjskih okolij. Nadalje bodo predstavljeni primerjava značilnosti urbanih in naravnih ekosistemov ter nekaj primerov potekajočih urbanih ekoloških študij na Finskem.

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