The dendrochronological potential of lime ( Tilia spp.) from trees at Hampton Court Palace, UK

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<ul><li><p>This article was downloaded by: [The University Of Melbourne Libraries]On: 12 May 2013, At: 10:59Publisher: Taylor &amp; FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK</p><p>Arboricultural Journal: TheInternational Journal of Urban ForestryPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/tarb20</p><p>The dendrochronological potential oflime (Tilia spp.) from trees at HamptonCourt Palace, UKAndy K. Moir a b &amp; Suzanne A.G. Leroy ba Tree-Ring Services, Hungerford, Berkshire, UKb Institute for the Environment, Brunel University, Uxbridge,London, UKPublished online: 13 Apr 2013.</p><p>To cite this article: Andy K. Moir &amp; Suzanne A.G. Leroy (2013): The dendrochronologicalpotential of lime (Tilia spp.) from trees at Hampton Court Palace, UK, Arboricultural Journal: TheInternational Journal of Urban Forestry, DOI:10.1080/03071375.2013.783173</p><p>To link to this article: http://dx.doi.org/10.1080/03071375.2013.783173</p><p>PLEASE SCROLL DOWN FOR ARTICLE</p><p>Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions</p><p>This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden.</p><p>The publisher does not give any warranty express or implied or make any representationthat the contents will be complete or accurate or up to date. The accuracy of anyinstructions, formulae, and drug doses should be independently verified with primarysources. The publisher shall not be liable for any loss, actions, claims, proceedings,demand, or costs or damages whatsoever or howsoever caused arising directly orindirectly in connection with or arising out of the use of this material.</p></li><li><p>The dendrochronological potential of lime (Tilia spp.) from treesat Hampton Court Palace, UK</p><p>Andy K. Moira,b* and Suzanne A.G. Leroyb</p><p>aTree-Ring Services, Hungerford, Berkshire, UK; bInstitute for the Environment, Brunel University,Uxbridge, London, UK</p><p>Common lime (Tilia europaea L.) and large-leaved lime (Tilia platyphyllos Scop.)are dendrochronologically and dendroclimatologically analysed for the first time. Limeis thought to be sensitive to climate change. Once a dominant species in Europe, it hasbeen in general decline from 3100 BC, but recently it has been found to be increasingthe northern limits of its range. Twenty-five trees from Hampton Court Palace (UK) arecross-matched to form a 138-year chronology spanning from AD 1866 to AD 2003.The relationships with climate were investigated using monthly instrumental records ofprecipitation and temperature from Kew between AD 1872 and AD 1997. The age ofthe lime trees was found to correlate well with girth (r 0.87). The annual resolutionof the chronology is robustly supported by regional cross-dating against established oakand yew chronologies. Summer precipitation (May, June and August) was shown to bea time-stable determinant of annual variation in radial growth. Problems of indistinctboundaries and missing rings, which become more prevalent in trees over 100 years ofage, may limit the dendrochronological potential of lime.</p><p>Keywords: climate change; dendrochronology; dendroclimatology; lime trees; Tilia;Hampton Court</p><p>Introduction</p><p>In arboriculture and urban forestry, the determination of tree age is useful to identify the</p><p>chronology of parks and gardens, to forecast future tree size and threats associated with</p><p>increasing age and to identify individuals of particular conservation value. Dendroclima-</p><p>tology, one of the sub-disciplines of dendrochronology, enables the identification of both</p><p>tree age and relationships between ring width and climatic variables. In areas where a</p><p>particular tree species is suitably responsive and long-lived and/or where past wood is</p><p>recoverable, the discipline may enable climate records to be reconstructed at annual</p><p>resolution, centuries before instrumental data are available. In the British Isles, the climatic</p><p>relationships of few tree species other than oak (Kelly, Leuschner, Briffa, &amp; Harris, 2002),</p><p>Scots Pine (Briffa et al., 2001; Moir, Leroy, &amp; Helama, 2011), yew (Moir, 1999) and elm</p><p>(Brett, 1978) have been examined. All these genera have well-defined rings suitable for</p><p>tree-ring analysis. Lime (Tilia spp.) has not been previously dendroclimatologically</p><p>analysed. This is possibly because it is only rarely found in old buildings and it has a</p><p>tendency to decay rapidly if damp. Furthermore, lime trees over 350400 years of age are</p><p>typically hollow (Pigott, 1989).</p><p>At the northern limits of its range in theLakeDistrict ofEngland, limehasbeenconsidered</p><p>a relict species, due to its limited production of fertile seeds and pollen evidence of decline</p><p>after 3100 year BC (Pigott &amp;Huntley, 1980). The small-leaved lime (Tilia cordataMill.) and</p><p>q 2013 Taylor &amp; Francis and Aboricultural Association</p><p>*Corresponding author. Email: akmoir@tree-ring.co.uk</p><p>Arboricultural Journal: The International Journal of Urban Forestry, 2013</p><p>http://dx.doi.org/10.1080/03071375.2013.783173</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [T</p><p>he U</p><p>nivers</p><p>ity O</p><p>f Melb</p><p>ourn</p><p>e Libr</p><p>aries</p><p>] at 1</p><p>0:59 1</p><p>2 May</p><p> 2013</p></li><li><p>large-leaved lime (Tilia platyphyllos Scop.) species are both native to the UK but are near the</p><p>northern limits of their European ranges. Small-leaved lime is essentially a continental species</p><p>known to require summer temperatures$208C at flowering for several consecutive days toproduce viable seed (Pigott &amp; Huntley, 1981). It has had difficulty growing from seed in the</p><p>UK under contemporary climatic conditions, but suitable conditions to permit fertilization</p><p>may have been more prevalent during the medieval warm period (Pigott, 1989). Recently,</p><p>Gray andGrist (2000) reported the natural regeneration of lime as far north as Perth, Scotland.</p><p>Large-leaved lime is nationally a scarce tree (Newlands, 1999).Where both small- and large-</p><p>leaved limes occur they can hybridise, resulting in common lime (Tilia europaeaL.),whichis also a widely planted ornamental tree.</p><p>Limes (Tilia spp.) are one of the tallest broad-leaved trees inmost areas of Great Britain.</p><p>They can achieve a height of 3540m, a diameter of 100300 cm and live up to 1000 years</p><p>(Mayer, 1977). Multi-stemmed self-coppicing limes can live much longer (Pigott, 1993).</p><p>Lime trees have played a major role as an architectural element in gardens in many</p><p>European countries since the late seventeenth century. Owing to their aesthetic value, lime</p><p>trees have become increasingly important in urban and open landscape in recent decades.</p><p>The avenues of a double row of lime trees on both sides of the Long Water at Hampton</p><p>Court Palace, UK, form the central feature of a great baroque patte doie layout (Figures 1</p><p>and 2). This was originally commissioned by King Charles II soon after his restoration in</p><p>AD1660. It is the finest surviving example of its kind inGreat Britain. The following history</p><p>of the lime trees at Hampton Court is summarised from a report by Gough (2000). Adrian</p><p>May, a royal gardener, purchased a consignment of 758 common limes fromHolland, which</p><p>were planted in AD 1661. The average life expectancy of a European lime tree is 200250</p><p>years, so the LongWater avenuewas in its prime at the beginning ofQueenVictorias reign.</p><p>A policy of gapping up those trees in the avenue, which had perished, was largely</p><p>unsuccessful due to competition with older trees. Many trees used in gaps were also a</p><p>different species of lime, or planted in the wrong positions, which resulted in a gap-toothed</p><p>canopy. The 1987 hurricane in Southern England affected the LongWater avenue badly. By</p><p>2000, the original population of 544 trees had dwindled to 300, with only 7 original tree</p><p>specimens remaining. The original trees were also a cause of problems as disease</p><p>(particularly several types of bracket fungus) and old age had left them in a dangerous</p><p>condition.</p><p>In 2003, the lime trees of the royal palace park in Hampton Court were felled (Figure 2)</p><p>to allow the replanting and restoration of the avenues, which presented a useful opportunity</p><p>for dendroclimatological and dendrochronological analysis. Indeed, on one hand, lime</p><p>should be considered if it has the potential to become a new proxy for estimating global</p><p>change; on the other hand, the dating of old lime trees will contribute to the corpus of</p><p>knowledge on gardens of a historically significant place. The aims of this research were (1)</p><p>to establish the ages of the trees sampled, (2) to establish relationships between the radial</p><p>growth and meteorological climate records, (3) to identify whether lime might be a useful</p><p>species in dendrochronology and (4) to interpret the ages of the sampled trees into the</p><p>cultural landscape of Hampton Court.</p><p>Materials and methods</p><p>Sampling and chronology building</p><p>Full trunk sections were sawn by operators at Hampton Court, typically from 20 to 30 cm</p><p>above the ground level. For practical reasons, V-section samples were cut across the widest</p><p>diameter to provide two radii for measurement (Figure 3). Standard dendrochronological</p><p>2 A.K. Moir and S.A.G. Leroy</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [T</p><p>he U</p><p>nivers</p><p>ity O</p><p>f Melb</p><p>ourn</p><p>e Libr</p><p>aries</p><p>] at 1</p><p>0:59 1</p><p>2 May</p><p> 2013</p></li><li><p>techniques were then utilised for sample preparation, measurement, cross-matching and</p><p>dating (Stokes &amp; Smiley, 1968). Cross-matches are reported using raw ring-width data and</p><p>the standard Students t-value statistic. Those t-values in excess of 3.5 are accepted as</p><p>significant where supported by visual comparison.</p><p>Growth rates</p><p>Tree-ring series commonly contain age trend, caused by the general reduction in the ring</p><p>width as trees get progressively older and pass through the formative, mature and senescent</p><p>phases of growth (White, 1998). For useful visual comparison between tree growth rates,</p><p>cumulative plots were produced to help emphasise the underlying biological age growth</p><p>trend (Figure 4).</p><p>Figure 1. Map of Western Europe showing the location of Hampton Court.</p><p>Arboricultural Journal: The International Journal of Urban Forestry 3</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [T</p><p>he U</p><p>nivers</p><p>ity O</p><p>f Melb</p><p>ourn</p><p>e Libr</p><p>aries</p><p>] at 1</p><p>0:59 1</p><p>2 May</p><p> 2013</p></li><li><p>Dendroclimatic analysis</p><p>The series were standardised (a process to remove age trends) using ARSTAN software</p><p>(Cook, Briffa, Shiyatov,&amp;Mazepa, 1990), andwere detrended using a negative exponential</p><p>curve or linear regression with power transformation (Cook &amp; Peters, 1997) to reduce</p><p>potential end-effect inflation of resultant indices. The chronology statistics generated from</p><p>the standardised series are described in Table 1. Mean sensitivity is a measure of the mean</p><p>relative change between adjacent ring widths (Fritts, 1976). Values over 0.30 are high and</p><p>indicate that the tree-ring series are highly responsive to environmental factors, while low</p><p>Figure 3. A V-section sample cut from a full section.</p><p>Figure 2. A standing and felled lime tree along the Long Water at Hampton Court Palace, UK.</p><p>4 A.K. Moir and S.A.G. Leroy</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [T</p><p>he U</p><p>nivers</p><p>ity O</p><p>f Melb</p><p>ourn</p><p>e Libr</p><p>aries</p><p>] at 1</p><p>0:59 1</p><p>2 May</p><p> 2013</p></li><li><p>values indicate weak inter-annual variance. The expressed population signal (EPS)</p><p>(Wigley, Briffa, &amp; Jones, 1984) measures the degree to which the chronology correlates (or</p><p>agrees) with a theoretical population chronology. The value of EPS ranges from 0 to 1, with</p><p>1 being the best possible value (the hypothetically perfect chronology).</p><p>Growthclimate relationships were examined using correlation functions as a</p><p>statistical model to compute coefficients between tree-ring chronologies and monthly</p><p>climatic variables (Blasing, Solomon, &amp; Duvick, 1984). These coefficients are univariate</p><p>estimates of Pearsons product moment correlation. Correlation function analyses and</p><p>moving interval correlation function analysis were carried out using DENDROCLIM2002</p><p>software (Biondi &amp; Waikul, 2004), which tests significance at the 0.05% level. A 14-</p><p>month analysis period extending from September in the year before growth to October of</p><p>the year of growth was selected. Residual tree-ring chronologies (which have proved to</p><p>Figure 4. Cumulative plot tree rings.</p><p>Table 1. General statistics of lime chronologies from the arstan standard chronology.</p><p>File name MS AR1 R(bt) SNR EPS</p><p>HPLIME 0.33 0.29 0.67 15.99 0.94</p><p>Note: Common interval 19101990. MS, mean sensitivity; AR1, first-order autocorrelation; R(bt), betweenseries correlation; SNR, signal to noise ratio; EPS, expressed population signal.</p><p>Arboricultural Journal: The International Journal of Urban Forestry 5</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [T</p><p>he U</p><p>nivers</p><p>ity O</p><p>f Melb</p><p>ourn</p><p>e Libr</p><p>aries</p><p>] at 1</p><p>0:59 1</p><p>2 May</p><p> 2013</p></li><li><p>yield more climatic information and minimise autocorrelation) were used with monthly</p><p>maximum temperature, minimum temperature and precipitation as predictors. Monthly</p><p>temperature and rainfall series for Kew (a meteorological station 9.5 km south west of</p><p>Hampton Court) were used in this analysis (Wales-Smith, 1980). Temperature and rainfall</p><p>can be intercorrelated causing an apparent negative association between temperature and</p><p>ring width when using correlation to examine climategrowth relationships, as</p><p>highlighted by Fritts (1976). To help resolve this problem, response function analysis</p><p>(which transforms the predictor variables into uncorrelated principal components) was</p><p>also carried out using DENDROCLIM2002. However, as response coefficients tend to be</p><p>lower than correlation coefficients the results are only summarised.</p><p>Results</p><p>Chronology</p><p>The results of the cross-matching between 25 samples against both oak and yew reference</p><p>chronologies are described below. The trees sections were generally quite circular in form</p><p>and showed no signs of hollowing. Pith was recovered in all cases. Twenty-five out of the</p><p>30 samples (83%) were successfully measured and cross-matched. Nineteen series were</p><p>from common lime and four from large-leaved lime. Two samples were labelled with the</p><p>same number, and therefore, could only be established as Tilia spp. The 25 cross-matched</p><p>together were used to form a chronology called HPLIME, which spans 18662003. The</p><p>annual resolution of this tree-ring series is confirmed by cross-matching against both oak</p><p>and yew existing reference chronologies (Table 2). The rings in years 1949/1950, 1964</p><p>and 1985 were the narrowest rings and most commonly missing. Instances of missing rings</p><p>were more frequent in older trees, i.e. after the first 80 years of growth. In five series where</p><p>the rings to bark could not be reliably measured, it was calculated that a missing ring</p><p>occurred on average once every 12 years, suggesting a 12% underestimation of tree age</p><p>from ring counts in lime trees over 50 years of age.</p><p>Growth rates and age</p><p>The ages and girths of the 25 cross-matched trees (Figure 4), together with five ring</p><p>counted trees, are plotted in Figure 5, and the following regression equation is calculated</p><p>as follows:</p><p>AGE 105:77 GIRTH in m2 11...</p></li></ul>