The use of micro-meteorological methods for the monitoring of the carbon fluxes in Karst ecosystems : doctoral dissertation

Ferlan, Mitja (avtor), Batič, Franc (mentor), Simončič, Primož (komentor)

Kljub intenzivnim raziskavam o kroženju ogljika so nekateri ekosistemi na tem področju še vedno slabo raziskani. Eni takšnih so tudi kraški ekosistemi. Raziskave predstavljene v tem delu so bile narejene na ravnini Podgorskega Krasa (400 - 430 m.n.v.) v sub-mediteranski regiji Slovenije. Na zaraščajočem območju sta bili izbrani dve ploskvi: pašnik in površina v zaraščanju. Na obeh ploskvah so bile v juliju 2008 vzpostavljene mikrometeorološke meritve po metodi Eddy covariance (EC) na višini 15 m (zaraščanje) in 2 m (pašnik). Prav tako so bile v okviru ploskev izvajane meritve dihanja tal z mikrometeorološko metodo zaprtih in odprtih komor ter vse potrebne spremljajoče meteorološke meritve. V preučevanem obdobju od 1. 7. 2008 do 30. 11. 2012 ni bilo med obema ploskvama zaznati večjih razlik v zračni temperaturi in količini padavin. Kar se tiče kvalitete podatkov pridobljenih po metodi EC, smo uporabili 59,7 % podatkov na ploskvi zaraščanje in 33,7 % podatkov na ploskvi pašnik. Ploskev zaraščanje je v preučevanem obdobju delovala kot ponor ogljika (NEE = -184 Ž 19 gCm-2leto-1), medtem ko je bila ploskev pašnik vir (NEE = 293 Ž 34 gCm-2leto-1) ogljika. Na podlagi mikrometeoroloških meritev po metodi EC lahko zaključimo, da zaraščanje pašnikov vpliva na povečano ponorno aktivnost ekosistema za ogljik. Ko smo na podatke NEE aplicirali B4 korekcijo, ki je potrebna zaradi samogretja merilne opreme, je ploskev zaraščanje delovala kot šibak ponor ogljika (NEE = -28 gCm-2leto-1), medtem ko je pašnik deloval kot vir (NEE = 456 gCm-2leto-1) ogljika. Ob aplikaciji korekcije NEE zaradi samogretja merilne opreme, ki je bila razvita na podlagi lastnih meritev (SISC), je ploskev zaraščanje delovala kot ponor ogljika (NEE = -127 gCm-2leto-1), medtem ko je pašnik deloval kot vir (NEE = 362 gCm-2leto-1) ogljika. Meritve so pokazale, da je potrebna tovrstna korekcija tudi v naših razmerah in ne le v hladnejših (Burbaet al., 2008), vendar mora biti uporabljena korekcija razvita na podlagi lastnih meritev. Kar zadeva meritev dihanja tal smo v študiji pokazali, da lahko avtomatski sistem za tovrstne meritve močno prispeva k večji časovni gotovosti meritev. Kombinacija meritev temperature in vlage tal skupaj z ročnimi meritvami dihanja tal pa močno prispeva k prostorki gotovosti meritev.

• Jezik: Angleški jezik
• Ključne besede: Kras, ekosistemi, sukcesija, kroženje ogljika, mikrometeorologija, Eddy kovarianca, dihanje tal, disertacije
• Vrsta gradiva: Doktorska disertacija
• Tipologija: 2.08 - Doktorska disertacija
• Organizacija: BF - Biotehniška fakulteta
• Status publikacije: Objavljeno
• Založnik: [M. Ferlan]
• Leto izida: 2013
• Št. strani: XII, 102 f.
• PID: 20.500.12556/RUL-76700
• UDK: 630*114(497.472)(043.3)
• COBISS.SI-ID: 770679
• Datum objave v RUL: 30.12.2015

Sekundarni jezik

• Jezik: Slovenski jezik
• Naslov: Spremljanje toka ogljika v kraških ekosistemih z mikrometeorološkimi metodami

Izvleček

Despite intensive research, carbon cycle is still under-investigated and not fully understood for many ecosystems, especially the ones which are of minor direct importance in terms of food and wood production. Karst ecosystems can be included in this group of ecosystems. The study was conducted at the Podgorski Kras plateau (400 - 430 m.a.s.l.), which was in the past subjected to agriculture land abandonment, in the sub-mediterranean region of Slovenia (SW Slovenia). Within the study area two study sites were chosen: grassland and forest succession. At both sites, in July 2008, an open-path Eddy covariance (EC) was installed at 15 m and 2 m height for Succession site and Grassland site, respectively. Also Rs and other auxiliary measurements were performed. For the observed period (July 1th 2008 - November 30th 2012) no major differences were measured between Grassland site and Succession site concerning air temperature and precipitation. Concerning the EC data quality for the observed period, 59.7% and 33.7% of expected data have not been discarded for Succession site and Grassland site, respectively. On the average annual basis Succession site was net sink of carbon (NEE = -184 Ž 19 gCm-2y-1) while Grassland site was a source of carbon (NEE = 293 Ž 34 gCm-2y-1). Based on the eddy covariance measurements it can be concluded that overgrown area increased sink activity compared to the extensive grassland in observed period. After B4 correction was applied on our datasets cumulative NEE fluxes changed. For observation period Succession site shifted to weak sink (-28 gCm-2y-1) of carbon, while the Grassland site remained a source (456gCm-2y-1). Applying SISC correction NEE changed to -127 gCm-2y-1 and 362 gCm-2y-1 for Succession site and Grassland site, respectively. Our measurements showed the need for self-heating correction also for our ecosystems. It is more appropriate to use site specific self-heating correction based and developed on own measurements than those suggested by Burba et al. (2008). Concerning the Rs measurements it can be concluded that knowledge of temporal variability can be greatly improved with an automatic system. Corresponding measurements of soil temperature and moisture together with manual Rs measurements, improved the knowledge about spatial variability of Rs.