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Interactions between climate, natural disturbances, and regeneration in boreal and hemi-boreal forests

Drobyshev, Igor LU (2004)
Abstract (Swedish)
Popular Abstract in Swedish

Naturliga störningsregimer är viktiga drivkrafter i vegetationsdynamiken hos de flesta skogstyper jorden runt. Att förstå de rumsliga och tidsmässiga egenskaperna i störningarna, såväl i nutid som i förfluten tid, är viktigt bl a vid utformningen av strategier för naturvård, likväl som för att kunna modellera inflytandet av klimat och människans påverkan. I denna avhandling har jag studerat störningar av vind och eld i naturliga gran- och talldominerade skogar i det europeiska Ryssland. Beträffande granskog (Picea abies (L.) Karst.) var målet att kvantitativt utvärdera rollen av naturligt förekommande luckor i skogarna, särskilt deras betydelse för föryngringen med olika trädslag. Vad gällde... (More)
Popular Abstract in Swedish

Naturliga störningsregimer är viktiga drivkrafter i vegetationsdynamiken hos de flesta skogstyper jorden runt. Att förstå de rumsliga och tidsmässiga egenskaperna i störningarna, såväl i nutid som i förfluten tid, är viktigt bl a vid utformningen av strategier för naturvård, likväl som för att kunna modellera inflytandet av klimat och människans påverkan. I denna avhandling har jag studerat störningar av vind och eld i naturliga gran- och talldominerade skogar i det europeiska Ryssland. Beträffande granskog (Picea abies (L.) Karst.) var målet att kvantitativt utvärdera rollen av naturligt förekommande luckor i skogarna, särskilt deras betydelse för föryngringen med olika trädslag. Vad gällde skogar dominerade av tall (Pinus sylvestris L.) analyserade jag sambanden mellan klimatisk variation, människans inflytande och förekomsten av bränder. Här var det primära målet att åstadkomma samband mellan årsringsvariabler och av dessa oberoende data på förekomsten av bränder, för att kunna dra slutsatser rörande kopplingar till klimatet som också avspeglades i de olika data-seten. Härigenom gjordes ett försök att bättre separera klimatiska signaler från människans inflytande i den lokala brandkronologin. Slutligen uppskattade jag sambandet mellan väderleksdata och brandförekomsten på en regional skala där årsringsinformationen fick företräda den regionala brandaktiviteten.



Mina studier i de grandominerade skogarna indikerade att inflytandet av vindstörningar på träddynamiken var beståndsspecifik vid en rumslig upplösning på 1000 ha och vid en tidsskala på några årtionden. En överensstämmelse mellan utfallet av föryngringen från gläntor och krontakets sammansättning kunde observeras i boreala bestånd. I hemi-boreala bestånd tycktes dålig granföryngring och större uppslag av löv i stora luckor leda till en ökad förekomst av lövträd i beståndet. Dessa föryngringsdata indikerade en minskad andel gran och mer löv för kommande årtionden.



I talldominerade skogar var det möjligt att visa på ett samband mellan årsringsvariabler och av dessa oberoende data på förekomsten av bränder från flera regioner. Det är viktigt att betona att detta samband berodde på överensstämmelse avseende tiden för bränderna, så som de återspeglades i brandärren. Samtidig analys av brandhistoriken i bestånd och de lokala årsringskronologierna indikerade att det bör vara möjligt att kvantitativt uppskatta det mänskliga inflytandet i den rekonstruerade brandhistoriken. På regional skala verkade årsringsbaserad rekonstruktion av brandförekomsten kunna ge en god prognos för hög eller låg brandrisk, att döma av indikationerna under ett halvt århundrande inom ett område av totalt 415.900 km2 i republiken Komi (osteuropeiska Ryssland). Mina resultat stödjer åsikten att årsringskronologier kan ge en realistisk bild av den regionala brandförekomsten i ett långt tidsperspektiv (> 600 år).



Generellt kan sägas att i varje konceptuell modell av vegetationsdynamik måste man inkorporera en betydande variation beroende på naturliga störningar i såväl tids- som rumsskala. Denna variabilitet blandas med mänskliga aktiviteter i såväl nutid som gången tid. För att ger bra praktiska råd vid utformningen av bevarandestrategier är det viktigt att skilja på rena klimatiska variabler och människans markanvändning. I hemi-boreal skog skulle människan kunna styra inriktningen på skötseln vid naturlig föryngring genom att större luckor normalt åtföljs av en större andel löv, medan små luckor ger upphov till framför allt granföryngring. (Less)
Abstract
Natural disturbance is an important driving force of community dynamics in many forest types around the globe. Understanding spatial and temporal properties of disturbance events in the present and in the past is important in formulating the nature conservation strategies as well as for the modeling of climate and human impacts on forest vegetation. In this thesis I studied wind and fire disturbances in natural spruce and pine dominated forests in European Russia.



In the case of Norway spruce (Picea abies (L.) Karst.) forests, the goal was to quantitatively evaluate the role of naturally formed canopy gaps and their role in canopy dynamics. In the case of Scots pine (Pinus sylvestris L.) dominated forests, I analysed the... (More)
Natural disturbance is an important driving force of community dynamics in many forest types around the globe. Understanding spatial and temporal properties of disturbance events in the present and in the past is important in formulating the nature conservation strategies as well as for the modeling of climate and human impacts on forest vegetation. In this thesis I studied wind and fire disturbances in natural spruce and pine dominated forests in European Russia.



In the case of Norway spruce (Picea abies (L.) Karst.) forests, the goal was to quantitatively evaluate the role of naturally formed canopy gaps and their role in canopy dynamics. In the case of Scots pine (Pinus sylvestris L.) dominated forests, I analysed the link between climate variation, human presence in the landscape, and fire activity. Here, the primary goal was to establish a relationship between tree-ring variables and independently dated fire events to infer common climatic information contained in both datasets. By doing so, an attempt was made to improve the separation of climate- and human-related influences in site fire chronologies. Finally, I analysed the link between weather variation and fire activity at the regional scale, and evaluated the value of tree-ring data as a proxy for regional-scale fire activity. My studies in the spruce-dominated forests suggested that the impact of wind disturbance on canopy dynamics may be forest-type specific at the spatial scale of 103 ha and the temporal scale of a few decades. An agreement between the outcome of gap-associated tree regeneration and canopy composition was observed in boreal stands. In the hemi-boreal stands, a large proportion of stand area under canopy gaps and poor spruce regeneration in larger gaps led to an increase in the abundance of deciduous species implying a decrease in canopy spruce and an increase in deciduous species in the coming decades.



In pine-dominated forests, it was possible to establish a relationship between tree-ring chronologies and independently dated fire events. Importantly, this relationship was dependent on the seasonal timing of fire events as recorded in the scars. Joint analysis of site fire histories and local tree-ring chronologies showed possibilities to quantitatively estimate the human impact in the reconstructed fire events. At regional scale, tree-ring-based reconstruction of fire activity appears to be a good predictor of high (annual) and low (decadal) frequency variability in the half-a-century long fire record of Komi republic (East European Russia, total area 415.9 thousand km2). My results supported the view of tree-ring chronologies as potentially realistic proxies for regional fire activity during longer time periods.



Generally, considerable variability of disturbance events along temporal and spatial scales needs to be incorporated in any conceptual model of vegetation dynamics. This variability is intermingled with human activities in the past and present. To provide a sound practical advice in designing conservation strategies it is important to separate purely climatic forcing of disturbance regimes from the one mediated by land use patterns. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Motta, Renzo
organization
alternative title
Samspel mellan klimat, naturliga störningar och föryngring i boreal och hemi-boreal skog
publishing date
type
Thesis
publication status
published
subject
keywords
conservation strategies, Plant ecology, Växtekologi, taiga, seasonal climate, shoot increment, larch, reconstruction, human, canopy gap, fire history, boreal, natural disturbances, dendrochronology
pages
150 pages
publisher
Section of Plant Ecology and Systematics, Ekologi Huset, S-223 62 Lund, Sweden,
defense location
Blå Hallen, Ekologi Huset, Lund
defense date
2004-03-26 10:15
ISBN
91-7105-205-4
language
English
LU publication?
yes
id
0a3ac048-a614-4c0a-bec0-07d1d0552dc1 (old id 466788)
date added to LUP
2007-09-04 11:02:57
date last changed
2016-09-19 08:45:08
@misc{0a3ac048-a614-4c0a-bec0-07d1d0552dc1,
  abstract     = {Natural disturbance is an important driving force of community dynamics in many forest types around the globe. Understanding spatial and temporal properties of disturbance events in the present and in the past is important in formulating the nature conservation strategies as well as for the modeling of climate and human impacts on forest vegetation. In this thesis I studied wind and fire disturbances in natural spruce and pine dominated forests in European Russia.<br/><br>
<br/><br>
In the case of Norway spruce (Picea abies (L.) Karst.) forests, the goal was to quantitatively evaluate the role of naturally formed canopy gaps and their role in canopy dynamics. In the case of Scots pine (Pinus sylvestris L.) dominated forests, I analysed the link between climate variation, human presence in the landscape, and fire activity. Here, the primary goal was to establish a relationship between tree-ring variables and independently dated fire events to infer common climatic information contained in both datasets. By doing so, an attempt was made to improve the separation of climate- and human-related influences in site fire chronologies. Finally, I analysed the link between weather variation and fire activity at the regional scale, and evaluated the value of tree-ring data as a proxy for regional-scale fire activity. My studies in the spruce-dominated forests suggested that the impact of wind disturbance on canopy dynamics may be forest-type specific at the spatial scale of 103 ha and the temporal scale of a few decades. An agreement between the outcome of gap-associated tree regeneration and canopy composition was observed in boreal stands. In the hemi-boreal stands, a large proportion of stand area under canopy gaps and poor spruce regeneration in larger gaps led to an increase in the abundance of deciduous species implying a decrease in canopy spruce and an increase in deciduous species in the coming decades.<br/><br>
<br/><br>
In pine-dominated forests, it was possible to establish a relationship between tree-ring chronologies and independently dated fire events. Importantly, this relationship was dependent on the seasonal timing of fire events as recorded in the scars. Joint analysis of site fire histories and local tree-ring chronologies showed possibilities to quantitatively estimate the human impact in the reconstructed fire events. At regional scale, tree-ring-based reconstruction of fire activity appears to be a good predictor of high (annual) and low (decadal) frequency variability in the half-a-century long fire record of Komi republic (East European Russia, total area 415.9 thousand km2). My results supported the view of tree-ring chronologies as potentially realistic proxies for regional fire activity during longer time periods.<br/><br>
<br/><br>
Generally, considerable variability of disturbance events along temporal and spatial scales needs to be incorporated in any conceptual model of vegetation dynamics. This variability is intermingled with human activities in the past and present. To provide a sound practical advice in designing conservation strategies it is important to separate purely climatic forcing of disturbance regimes from the one mediated by land use patterns.},
  author       = {Drobyshev, Igor},
  isbn         = {91-7105-205-4},
  keyword      = {conservation strategies,Plant ecology,Växtekologi,taiga,seasonal climate,shoot increment,larch,reconstruction,human,canopy gap,fire history,boreal,natural disturbances,dendrochronology},
  language     = {eng},
  pages        = {150},
  publisher    = {ARRAY(0xab32de8)},
  title        = {Interactions between climate, natural disturbances, and regeneration in boreal and hemi-boreal forests},
  year         = {2004},
}