Modeling radial growth increment of black alder (Alnus glutionsa (L.) Gaertn.) tree

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  • ecolog ical modell ing 2 1 5 ( 2 0 0 8 ) 180189

    avai lab le at www.sc iencedi rec t .com

    journa l homepage: www.e lsev ier .com/ locate /eco lmodel

    Modeling radial growth increment of black alder (Alnusglutio

    Jana Lag akb

    a Laboratory 3, Nb Departmen ublja

    a r t i c l e i n f o

    Article history:

    Published on line 8 April 2008

    Keywords:

    Wetland for

    Black alder

    Forest grow

    Feature sele

    Machine lea

    STELLA mod

    a b s t r a c t

    Nowadays it is extremely important to understand ecosystem function and its dynamics to

    predict future changes and consequently to perform appropriate measures. Hydromeliora-

    1. In

    The undersof ecologicwhich we hand interesclimate contems is thagrowth is d

    CorresponTel.: +386 53

    E-mail a0304-3800/$doi:10.1016/est

    th model

    ction

    rning

    el

    tions and subsequent decrease in groundwater table are thought to be a major reason for

    a decline in the vitality of black alder (Alnus glutinosa (L.) Gaertn.) wetland forests in North-

    eastern Slovenia. In this study radial increments of trees were used as indicators of black

    alder forest function and its disturbances. The aim of the study was to build a model of

    annual radial increments of black alder trees, to use this model to identify environmental

    attributes that most importantly affect ecosystems function and to predict changes in the

    forest function under different scenarios of environmental conditions in the future. The

    model was induced with a machine learning algorithm CIPER and it was based on the data

    about site conditions and applied management measures in the past 35 years. Groundwa-

    ter levels in combination with the duration of sun radiation were identied as the most

    important environmental attributes affecting annual radial increments. Radial increments

    were the lowest in very wet and cloudy years. On the other hand, radial increments were

    decreased under drought stress aswell. Changes in groundwater level and in duration of sun

    radiation, aswell as increased oscillations of groundwater level, all cause important increase

    in oscillations of modeled radial increments, indicating higher stress. Radial increments

    were further negatively affected by late white frosts in the spring.

    2008 Elsevier B.V. All rights reserved.

    troduction

    tanding of ecosystem function and reconstructional niche are especially important in this period inave to carefully balance between different needsts and in which we expect important changes ofditions. An important property of forest ecosys-t they mark annual radial growth increments. Asependent on ecosystems well-being and function

    ding author at: University of Nova Gorica, Laboratory for Environmental Research, Vipavska 13, SI-5001 Nova Gorica, Slovenia.3 15 328; fax: +386 533 15 296.ddresses: jana.laganis@p-ng.si (J. Laganis), aleksandar.peckov@ijs.si (A. Peckov), marko.debeljak@ijs.si (M. Debeljak).

    in individual years, radial increments can be regarded as reli-able indicators of ecosystem function.

    Black alder (Alnus glutinosa (L.) Gaertn.; f. Betulaceae) is adeciduous tree species with many special ecological prop-erties as well as of an economical importance. Its mostimportant ecological properties are adaptations to highgroundwater level, nitrogen xation through symbiosis withactinomycetes Frankia, fast growth and short lifetime, andlight pretentiousness. In the stands under study it is also

    see front matter 2008 Elsevier B.V. All rights reserved.j.ecolmodel.2008.02.018nsa (L.) Gaertn.) tree

    anisa,, Aleksandar Peckovb, Marko Debeljfor Environmental Research, University of Nova Gorica, Vipavska 1t of Knowledge Technologies, Jozef Stefan Institute, Jamova 39, Ljova Gorica, Sloveniana, Slovenia

  • ecolog ical modell ing 2 1 5 ( 2 0 0 8 ) 180189 181

    reported to be resistant to white frosts, diseases and herbi-vores (Nemesszeghy, 1986; Brus, 2005).

    Homogenortheastenatural we(Nemesszeicantly redvitality ofmiddle of tLevanic, 19in Europe (to a decreachangedhyrations andand hydrolothe studiesently clearand standceed to profor forest de1993; Caterwe conductforest of Po

    Radial genvironmeparticular smate condgrowth of tbination ofreason we ction and disin individu

    The maiulation growas used tothat affectand to predfuture clim

    2. Ma

    2.1. Stu

    2.1.1. SiteThe forestleft side ofin these stand oak (3%ble alder fo(Culiberg, 1best sites a30m are re1953; DawsFeatherstonstand undein individu

    Black al(Forest Maalready sur

    uary 2005. The latitude of the research site is 46,595 and itslongitude is 16,358. The area is at and it is about 190m above

    leve

    Clilectemme. Imnt lain thd tolturaver, 19

    owinmmeties pr, 19umn thj, 19s is tmon ofandowlyIn ousurf

    anua

    s ad wieic ein deevanhysiant

    ling deralen is

    HisingofW18thvereed

    sts wic anaininwatg (Le953 aThend ffor assze980erbenous forests of black alder in the lowlands ofrn Slovenia are among the last remnants oftland forests of this species in central Europeghy, 1986). The area of these forests was signif-uced in the 19th century. Severe decline in thestands in the studied area was observed in thehe last century (Wraber, 1951; Nemesszeghy, 1986;93) as well as in other black alder oodplain forestsPretzell et al., 1997). This decline was attributedse in groundwater table (Pretzell et al., 1997) anddrological conditions due to extensive hydromelio-regulations. The importance of groundwater levelgic regime for wetland trees was also conrmed inof Keeland and Sharitz (1997). Despite the appar-causal relationship between the groundwater levelvitality, studies performed until now did not suc-ve changes in groundwater level as a major reasoncline (Levanic andKotar, 1996; Kosir, 1987; Levanic,, 2002). In order to continue with this discussioned a case study research in a black alder oodplainlanski Log.rowth of trees is inuenced by a complex ofntal parameters (attributes) that take place on aite. These attributes include water availability, cli-itions and soil fertility (Whitehead, 1998). Radialrees responds very dynamically to a current com-environmental attributes (Waring, 1987). For thatonsidered radial increments as indicators of func-turbances of black alder wetland forest ecosystemal years.n goal of this study was to construct a reliable sim-wth model of black alder forest stand. This modelidentify the set of the most important attributes

    growth and development of the stand under studyict changes in the function of these stands underate change scenarios.

    terials and methods

    dy site

    descriptionof Polanski Log covers the area of 414ha on thethe Ledava River. The most common tree speciesands is black alder (85%), followed by ash (12%)) (Nemesszeghy, 1986). Long-term presence of sta-rests was proved in a research of subfossil wood989). These stands can be classied as black aldersnd as a climax community. Whereas heights up toported for black alder in other countries (McVean,on and Funk, 1981; Brus, 2005; Krstinic et al., 2002;e, 2003), they surpassed the height of 34m in ther study (Nemesszeghy, 1986; Laganis, 2007). Treesal plots are even-aged.der represents 95% of trees in the selected standnagement Plans, 19712011). With 69 years itpassed its maturity and it was cut down in Jan-

    the sea

    2.1.2.The sehot su910 Cfrequefrostsreporte(Silvicu

    The(Wrabethe grthe suproper(Wrabemaximbetwee(SmoleRiver a

    Thefunctiowatervery sl1993).to the2004Jown.

    Thicoverehypoglvaries1951; Lpoor pAscendprevaiof minNitrog1988).

    2.1.3.Accordreportsin thewas coperformof fore(Levanof remgroundoodinyears 160 cm.2005) apriate(Neme

    In 1the rivl.

    mate and soil conditionsd site lies in a Panonic-type of climatewith dry andrs and cold winters. Mean annual temperature isportant for the vegetation are negative impacts ofte frosts in the spring (until April) and early whitee autumn (Wraber, 1951), despite they were notcause important damage in black alder stands

    al chronicles).rage amount of precipitation is only about 800mm51), a bit less than 60% of which occurs duringg period (Ziberna, 1992). Severe droughts duringr and relatively poor physical and chemical soilrevent higher agricultural productivity in this area51). The amplitude between the minimum andgroundwater level was found to be about 1.5me years 1953 and 1993 in about 7-km distant well95), which is of a similar distance from the Ledavahe selected stand.st important attributes that affect structure andthese forests are hydrological conditions of soilwater regime. Soil water is standstill or it owsthrough a gravely substrate (Wraber, 1951; Levanic,r stand the groundwater level was relatively closeace (080 cm) during measurements (Septemberry 2005). In some cases the stand was partly over-

    t area has gravelly to sandy siliceous grounding,th fertile, clayey alluvium (intrazonal type of soil,ugley; Wraber, 1951; Kalan, 1988). This alluviumpth but in general it is relatively shallow (Wraber,ic, 1993). A shortage of limestone is a reason forcal and chemical soil properties (Wraber, 1951).groundwater ows toward the surface (upward) areuring the vegetation period and they bring plentynutrients to the upper soil layers (Kalan, 1988).reported to be abundant (Levanic, 1993; Kalan,

    toryto the Forest Management Plans (19591968) andraber (1951) large part of the area was uncrossablecentury due to high water levels. The landscaped by oak and alder forests. Several meliorationsafter the year 1814 drained the area, large extentsere cleared to obtain new agricultural surfaces

    d Kotar, 1996; Nemesszeghy, 1986) and large partg forests was endangered due to a decrease in theer leve