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Biomass production from traditional coppicemanagement in northern Italy

Raffaele Spinelli a,*, Andrea Ebone b, Marco Gianella b

aCNR e IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Florence, Italyb IPLA, C.so Casale, 476, I-10132 Torino, Italy

a r t i c l e i n f o

Article history:

Received 25 June 2013

Received in revised form

12 January 2014

Accepted 17 January 2014

Available online 8 February 2014

Keywords:

Logging

Yarder

Forwarder

Economics

Yield

Cost

* Corresponding author.E-mail address: spinelli@ivalsa.cnr.it (R. S

0961-9534/$ e see front matter ª 2014 Elsevhttp://dx.doi.org/10.1016/j.biombioe.2014.01.0

a b s t r a c t

Traditional coppice stands cover millions of hectares throughout Europe and offer large

amounts of biomass. The study analyzed 10 commercial coppice harvesting operations in

northwestern Italy, where modern machines were deployed. Removals, prices, work, rev-

enues and costs were carefully determined. Firewood was the main product, representing

between 70% and 100% of the total product mass and value. Traditional coppice stands

often yield over 200 m3 of energy biomass per hectare, at the time of cut. Cable yarding

operations were better organized than ground-based operations, which explained why

they incurred the same harvesting cost, despite the more challenging site conditions under

which they were deployed. Mean harvesting cost was 45Vm�3, of which about 10% was

needed for felling, 70% for extraction and processing, and the remaining 20% for loading

and transportation. All operations accrued some profit, which varied between 13 and

43Vm�3 or between 1600 and 8600V ha�1, depending on operational efficiency, value re-

covery and stand yield.

ª 2014 Elsevier Ltd. All rights reserved.

1. Introduction

The long and intense settlement history makes human ac-

tivity a characterizing factor of European forestry [1]. Old

growth is relegated to few remote areas, which have remained

inaccessible due to the peculiar combination of many con-

current factors [2]. Most forests are under activemanagement,

or have been under active management until recent years [3].

That explains the relative abundance of coppice stands, which

are best suited to satisfy the needs of a dense rural population

[4]. In particular, coppice stands are very efficient, due to the

short waiting time (15e30 year rotations) and simplified

management (clear-cut at the end of rotation). For centuries,

these forests have provided local communities with firewood,

pinelli).ier Ltd. All rights reserve14

posts, tool handles and fencing materials [5]. In the last de-

cades, coppice economy has suffered from the competition of

oil and plastic, resulting in a reduced interest toward coppice

management [6]. What is more, industrialization has reduced

the availability of rural labor, and their propensity to perform

heavy and low-paying jobs. The obvious solution is mecha-

nization, which is especially challenging in the case of coppice

stands. These forests grow on steep terrain and produce

relatively small stems, which severely restrictmachine access

and productivity [7]. Nevertheless, there is a strong interest in

restoring the economic role of traditional coppice stands,

which covermillions of hectares throughout Europe [8]. These

stands may play a crucial role in supporting rural develop-

ment, while providing a wealth of new products and services,

especially biodiversity, energy biomass and carbon

d.

b i om a s s a n d b i o e n e r g y 6 2 ( 2 0 1 4 ) 6 8e7 3 69

sequestration [9]. The example of Italy is eloquent enough.

Traditional coppice stands cover almost 4 million hectares

and represent over half of the total forest surface [10]. More

millions of hectares are available in France, Spain, Greece and

the Balkans [11]. Even conifer-dominated landscapes like

those of Austria and Germany, offer a sizable coppice

resource, often unutilized [12]. Therefore, European foresters

have a keen interest in finding a viable solution to coppice

management, with a view to biomass production. In fact,

many forest enterprises have already explored a number of

options, including modern mechanized equipment. The goal

of this study was to sample a number of these innovative

operations for determining their technical and financial effi-

ciency. In particular we set out to determine value recovery,

productivity, cost and revenues with accurate scientific

methods.

2. Materials and methods

The study was conducted in Piemonte, northwestern Italy.

The study material consisted of 10 commercial operations

selected in order to represent: (1) two very common coppice

stand types, and namely: chestnut (Castanea sativa L.) and

beech (Fagus sylvatica L.) forests; (2) both ground-based and

cable operations; (3) innovative harvesting technologies for

coppice, and in particular: forwarders in ground-based oper-

ations and mobile yarders in cable operations. In all cases,

felling was performed motor-manually with chainsaws. Pro-

cessing was partly or fully mechanized, through the use of

grapple-saws or processors, respectively (Table 1). Re-

searchers carefully observed each operation and broke it

down to its basic work phases, as follows: felling, delimbing,

crosscutting, bunching, extraction, transportation. More

phases could be merged into a single one, in which case just

one phase was counted. Otherwise, the same phase could be

repeated several times, in which case each repetition was

counted as a separate phase. The total number of phases was

taken as a measure of operational efficiency, on the assump-

tion that streamlined operations would include the lowest

number of phases.

Stand characteristics were determined with conventional

stand cruising techniques, on three 100 m2 plots per site.

Stand characteristics are shown in Table 2. Total worksite

Table 1 e Description of the study operations.

Operation n� Place name Technology type System type

1 Rivalta di Torino Ground-based CTL

2 Cossila S. Grato Cable yarding WTH

3 Sala Biellese Ground-based WTH

4 Rora Cable yarding WTH

5 Limone P.te Cable yarding WTH

6 Camandona Cable yarding WTH

7 Magnano Groundebased CTL

8 Pamparato Ground-based CTL

9 Vernante Cable yarding WTH

10 Rittana Ground-based CTL

Notes: CTL¼ cut-to-length (trees are extracted after delimbing and cros

vesting (trees are extracted whole and processed at the landing, after ext

area was obtained from the harvesting plans. At the end of

each harvest, the operation manager provided the total

amount of wood harvested, divided by assortment type. He

also communicated the sale price for each assortment, so that

total value recovery could be estimated.

Labor and machine inputs were estimated through a shift-

level study conducted for thewhole duration of the harvesting

operation [13]. Crew supervisors noted all man and machine

hours invested into harvesting, separately for each work

phase. They also recorded fuel consumption, as well as the

hourly cost of their equipment and personnel. Declared costs

were compared with the official regional rates in order to

check inconsistent declarations. Eventual inconsistencies

were double-checked and rectified, if the operators could offer

no reasonable explanation. The study included all work pha-

ses, from felling to transportation.

The shift-level study was integrated with work sampling

sessions, conducted on at least three one-hour periods for

each operation and work phase. The purpose of work sam-

pling was that of estimating the incidence of delays, so as to

target future improvements.

While observations were equally divided between extrac-

tion options (i.e. ground-based and cable yarding), the study

did not follow a proper factorial design. Therefore, differences

were tested independently for stand types and operation

types, on the assumption that in this case tree species did not

play amain role onmachine productivity and harvesting cost.

Due to the frequent violation of the normality assumption,

non-parametric techniques were used to test the statistical

significance of differences between treatments.

The study material consisted of 26 ha, which yielded over

4000 m3 of wood (solid, or solid equivalent). Overall, re-

searchers conducted 88 work sampling sessions, lasting a

total of 97.5 h. The total value of all products harvested

amounted to almost 300,000 V, whereas the total harvesting

and transportation cost was about 200,000 V.

3. Results

All stands were considerably older than the prescribed mini-

mum rotation, which was around 12 years for chestnut and 25

years for beech. That was the result of the decreased interest

toward coppice products, which has caused generalized

Extraction equipment Processing equipment Phases n�

Forwarder JD1410 Grapple-saw 5

Savall 1500 Grapple-saw 4

Farm tractor Chipping 5

Konrad Woodliner Grapple-saw 5

Konrad Woodliner Processor 3

Savall 1500 Grapple-saw 3

Forwarder JD1410 Grapple-saw 8

Forwarder JD810 Grapple-saw 5

Konrad Woodliner Grapple-saw 3

Farm tractor Loader 4

scutting into final length or multiples); and WTH¼whole-tree har-

raction).

Table

2e

Sitedesc

ription.

Operationn�

Standtype

Treatm

enttype

Age,

yea

rsSurface

,ha

Slope,

%Density

trees

,ha�1

Volum

e,m

3tree�1

DBH,cm

Stock

ing,

m3ha�1

Removal,m

3ha�1

Intensity,%

1Chestnut

Clear-cu

t40

4.98

15

1115

0.20

24.3

226

92

41

2Chestnut

Clear-cu

t40

1.09

45

605

0.56

26.6

338

74

22

3Chestnut

Thinning

20

4.87

25

1322

0.20

13.1

270

109

40

4Beech

Thinning

60

4.00

55

955

0.25

22.2

237

143

60

5Beech

Clear-cu

t60

1.46

30

1067

0.29

19.6

310

274

88

6Chestnut

Thinning

20

1.26

35

1226

0.31

21.3

385

156

41

7Chestnut

Thinning

20

2.63

22

1847

0.23

13.4

420

243

58

8Beech

Clear-cu

t60

3.14

50

1895

0.14

12.1

260

223

86

9Beech

Clear-cu

t50

2.06

45

1927

0.12

16.4

231

188

81

10

Chestnut

Clear-cu

t30

0.53

40

2038

0.21

15.4

420

220

52

Mean

Chestnut

e28

2.56

30

1358

0.28

19.0

343

149

42

Mean

Beech

e58

2.66

45

1461

0.20

17.6

259

207

79

p-V

alue

ee

0.0085

0.6698

0.0691

0.9999

0.3923

0.6698

0.1344

0.2008

0.0103

Notes:

DBH¼diameteratbreast

height;andintensity

¼100�removal/stock

ing.

b i om a s s a n d b i o e n e r g y 6 2 ( 2 0 1 4 ) 6 8e7 370

abandonment over the last decades. This was especially the

case of beech stands, which were located on steeper sites and

were twice as old. Harvesting intensity was higher in beech

stands, which resulted in larger removals, despite the smaller

initial stocking and a lower tree size (although tree size dif-

ferences were not statistically significant).

Fig. 1 shows the volume (a) and the value (b) of the total

harvest obtained from each operation, divided by product

type. The maximum number of possible products was 4, and

namely: timber, fencing assortments, firewood and chips.

Their actual prices are shown in Table 3.

Firewood was the main product in 8 operations out of 10,

representing between 70% and 100% of the total product mass

and value. Timber and fencing assortments were only recov-

ered from chestnut stands, whereas beech stands only pro-

duced energy assortments. Beech firewood was especially

valuable, and obtained about the same price as the fencing

assortments harvested from chestnut stands. In contrast,

chestnut firewood obtained a lower price than beech firewood

(64Vm�3 vs. 79Vm�3, p¼ 0.0094 according to the Man-

neWhitney test), which justifiedmanufacturing of alternative

products.

Table 4 shows the mean productivity recorded for each of

the main forest equipment types, as obtained from shift-

level reports and work sampling sessions. The latter

returned significantly higher productivity figures (p¼ 0.0003

according to the pairedWilcoxon test), because they were too

short for capturing the effect of erratic delay time. Never-

theless, differences between equipment were consistent for

both methods. Tractor extraction achieved similar produc-

tivity as yarder extraction. The only real improvement was

obtained when introducing a forwarder to ground-based

extraction operations. Tractors, yarders and grapple-saws

achieved about the same production levels, because they

generally worked in a sequence. Interdependence meant that

the faster had to wait for the slower, which leveled out any

differences. In this case, the grapple-saw was the faster

equipment type, which could have reached a higher pro-

ductivity if it had not been limited by the extraction unit that

fed it with new trees.

Poor road standards explained the general use of three-

axle trucks and farm tractors for transportation. Tractors

were equipped with 10 t trailers and had a lower mean

payload than trucks (9.7 vs. 18.7 m3, p¼ 0.0004 according to

the ManneWhitney test). They also covered significantly

shorter distances (21 vs. 54 km, p¼ 0.0392 according to the

same test). Mean transport cost was estimated to 0.38 and

0.13Vm�3 km�1 for the tractor and the truck, respectively.

Loading was carried out with the loader of a forwarder or an

excavator. This work phase was very fast, and took from

10 min to less than an hour, depending on product type and

vehicle capacity.

Chipping was less frequent than expected. It occurred on 2

operations out of 10, and was conducted with light industrial

chippers in the 150 kW power class. Chipping productivity

was 7.1 m3 h�1 in operation 3 and 6.6 m3 h�1 in operation 9.

These values were consistent with chipper size and feedstock

characteristics [14].

Total harvesting cost ranged from 31 to 59Vm�3 (Fig. 2).

Cost was lowest in operation 2, due to the efficient

Fig. 1 e Product volume (a) and value (b), by assortment type.

b i om a s s a n d b i o e n e r g y 6 2 ( 2 0 1 4 ) 6 8e7 3 71

organization and the large tree size; it was highest in

operation 8, where ground-based harvesting was applied to

a steep site, more suitable for cable yarding. Mean har-

vesting cost was 45Vm�3, of which about 10% was needed

for felling, 70% for extraction and processing, and the

remaining 20% for loading and transportation. Statistical

analysis did not detect any significant difference between

the mean costs of ground-based operations and cable

yarding operations (p¼ 0.9168). The latter were confronted

with harsher terrain conditions, but were better organized

and more efficient, as witnessed by the significantly lower

number of work phases per operation (a mean of 5 vs. 7

phases, p¼ 0.0135).

Table 5 shows the cost, revenue and profit of each oper-

ation. The result was highly variable, and depended on a

number of factors, including operational efficiency, value

recovery and coppice yield. All operations accrued some

profit, which varied between 13 and 43Vm�3 or between

1600 and 8600Vha�1. Profit per m3 was highest in operation

6, where high operational efficiency was matched by high

value recovery; it was lowest in operation 10, where value

recovery was low, because all harvest was processed into

firewood logs, eventually sold to a tannin extraction plant.

This ranking was changed when profit was expressed on a

per hectare base. Then, the effect of stand yield became

dominant, and profit was highest in the operation with the

highest yield per hectare (operation 5) and lowest in the

lowest-yielding site (operation 1).

Table 3 e Assortment price for each operation (V mL3,delivered).

Operation Fencing Timber Firewood Chips Stand

1 e e 67 e Chestnut

2 e e 73 e Chestnut

3 55 100 65 75 Chestnut

4 e e 77 e Beech

5 e e 80 e Beech

6 65 e 73 e Chestnut

7 80 98 59 e Chestnut

8 e e 80 e Beech

9 e e 80 55 Beech

10 e e 48 e Chestnut

Note: firewood was produced as 2-m long logs.

4. Discussion

The difference between chestnut and beech coppice stands is

related to the different sites occupied by the two species.

Beech grows at higher elevations, on steeper and less fertile

sites, which explains both the longer rotations and the lower

yields. Chestnut is generally grown on richer sites, and offers

better yields. However, most chestnut stands in Piemonte

have suffered from bark canker and neglect, with a negative

effect on stem quality. Crook, ring shake and other defects are

very frequent, which reduce potential value recovery. Many

stems have to be chipped or processed into firewood, because

their quality is not suitable for the production of timber or

fencing assortments, even when their size would match

specifications. Therefore, unanimous preference for firewood

results from the combination of poor stand quality and

attractive firewood prices. The former precludes a larger role

to structural products, while the latter drives the choice be-

tween firewood, pulpwood and fuel chips. Firewood still ob-

tains the best price. Besides, the demand for chips is limited

compared to the demand for firewood, which the national

statistics estimate to 3 and 18 million tons per year, respec-

tively [15,16].

In general, the machine productivity figures found in this

study are very similar to those reported in previous studies of

ground-based [17] and cable technology [18e20], as applied to

Italian coppice stands. The substantial difference between the

results of short and long-term studies is logical, and it is easily

explained by the effect of erratic delay time, poorly repre-

sented by short-term study sessions [21].

One of the most important findings of this research is that

cable operationsmay not incur higher cost than ground-based

operations, at least for the conditions observed in the study.

Table 4 e Mean productivity (m3 hL1) of the mainequipment types as obtained from shift-level and worksampling records.

Work phase Equipment Work-sampling Shift-level

Extraction Forwarder 15.5 9.6

Felling Chainsaw 11.6 8.2

Processing Grapple-saw 6.8 4.9

Extraction Yarder 5.9 4.7

Extraction Farm tractor 6.5 5.1

Fig. 2 e Harvesting cost by operation and work phase.

b i om a s s a n d b i o e n e r g y 6 2 ( 2 0 1 4 ) 6 8e7 372

Although cable yarders are less productive than modern

ground-based equipment, cable operations recover the

handicap through a much better organization, resulting in

fewer work phases. In contrast, ground-based operations

involve repeated handling, with each additional phase incur-

ring additional cost. Trees were often processed twice, before

and after extraction. In many cases, semi-processed trees

were pre-bunched before extraction, using a winch or a small

excavator, depending on terrain conditions. The inefficient

organization ofmost ground-based operations is likely related

to incomplete mechanization. The classic Scandinavian cut-

to-length system is based on the harvester-forwarder team.

Introducing one machine without the other cannot achieve

the same effect, and our study proves sufficient witness for

that. Without the harvester, the forwarder must be supported

by inefficient ground teams for processing and bunching the

trees, or it must wander across the stand to pick up few small

logs at a time. That may also explain why forwarder produc-

tivity in this study is lower than reported in other studies

conducted further north. Until now, harvesters have found

limited use in coppice operations due to the difficulties

encountered when felling coppice trees, which grow in

clumps and are difficult to handle with most harvester heads.

Limited investment capacity is another reason for buying only

one of the two machines, in this case the forwarder, which

best emulates the existing equipment [22]. That also explains

Table 5 e Cost, revenues and profit for each of the study opera

Operation n� Technology type Vm

Cost Reven

1 Ground-based 50.1 67.7

2 Cable yarding 31.2 73.0

3 Ground-based 39.6 72.5

4 Cable yarding 52.3 77.4

5 Cable yarding 48.7 80.0

6 Cable yarding 35.8 78.6

7 Groundebased 48.2 65.1

8 Ground-based 59.6 80.0

9 Cable yarding 51.0 72.5

10 Ground-based 35.2 48.0

Mean 45.2 71.5

thewidespread popularity of grapple-saws, partly aided by the

loose quality specifications applied to coppice products, which

make rough processing an acceptable practice. In fact,

ground-breaking research is now addressing the introduction

of mechanized felling to coppice operations, which may soon

change this picture and encourage a further rationalization of

ground-based coppice harvesting [23]. Furthermore, cable

yarding operations may be safer than ground-based opera-

tions, which makes them especially attractive [24].

All operations in the study returned some profit, and often

quite a large one. This may contradict the common view that

small-tree harvesting offers minimal gains, or incurs financial

losses. In this respect, we need to stress that we sampled

commercial operations. By definition, these operations are

conducted with the main goal to accrue some profit, only

where conditions are favorable to cost-effective harvesting.

Stands under commercial management may not reflect the

average conditions of coppice stands in the region, but only of

those stands that is worth harvesting. The sites sampled with

this study offered the right combination of high yield, good

product quality and ease of access that made harvesting

financially viable. Especially important were the good price

levels currently fetched by traditional firewood and the high

stocking of most stands. In fact, all forests in this study were

much older than their conventional rotations and had accu-

mulated relatively large product volumes. With two excep-

tions, removals varied between 100 and over 200 m3 ha�1, and

were similar to the removals in some high forest types,

especially if these forest were treated with selection or

shelter-wood cuts. Of course, the profit estimated in this study

is not the profit accrued by the logging company alone, but the

difference between total product value and harvesting cost.

This difference must cover harvesting profit as well as forest

owner revenues, in the form of a stumpage price.

5. Conclusions

Modern mechanization is being introduced to coppice har-

vesting operations in order to reduce costs, increase safety

andmitigate labor shortage. Modernization is still in progress,

which explains the presence of intermediate solutions, espe-

cially for what concerns ground-based operations. These

tions.�3 Vha�1

ue Profit Cost Revenue Profit

17.6 4626 6251 1625

41.8 2293 5371 3078

32.9 4306 7886 3579

25.1 7483 11,073 3590

31.4 13,330 21,920 8590

42.9 5575 12,257 6682

17.0 11,697 15,825 4128

20.4 13,292 17,840 4548

21.5 9564 13,591 4027

12.8 7744 10,560 2816

26.3 7991 12,257 4266

b i om a s s a n d b i o e n e r g y 6 2 ( 2 0 1 4 ) 6 8e7 3 73

operations will need further improvement, before their po-

tential is fully expressed. In contrast, cable yarding operations

are better organized and offer competitive harvesting cost,

despite the challenging site conditions in which they are

deployed. In both cases, coppice harvesting returns sizable

profits, due to a favorable combination of high yields and

attractive product price. Traditional coppice under sustain-

ablemanagement configures as an important source of energy

biomass.

Acknowledgments

This study was funded by Regione Piemonte, within the scope

of the RENEFOR Project (European Union Programme France-

Italy ALCOTRA 2003-2007).

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