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Variations of Soil Physico-Chemical and Biological Features after Logging Using Two Different Ground-Based Extraction Methods in a Beech High Forest-A Case Study

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Considering that forests are crucial in the ecosystem of our planet and that forests provide timber products as well as several ecosystem services, it is evident that the application of sustainable forest operations (SFOs) is of substantial importance to achieve sustainable forest management (SFM). One of the most important issues to be evaluated when dealing with SFOs is limiting the disturbance and impacts related to logging. Harvesting activities can indeed alter the conditions of soil through compaction and litter removal which can also lead to modifications from the biological point of view, for example, diminishing the presence of soil microarthropods. While keeping these objectives in focus, the aim of the present study was to evaluate physico-chemical and biological impacts on forest soil in Mediterranean beech forests after forest logging with two different extraction systems, which are forestry-fitted farm tractors equipped with winch and forwarder. Specifically , authors aimed to investigate: i) soil disturbance levels of ground-based extraction methods; ii) soil disturbance levels of the applied forestry intervention; iii) soil disturbance levels between winching-skidding and forwarding. Findings showed that the physical, chemical, and biological soil features were slightly disturbed by the forestry itself. In addition, forest operations and machine traffic showed clear soil disturbance, resulting in a substantial alteration of the characteristics. Between the two extraction techniques tested, winching caused less disturbance while forwarding had stronger impacts. However, it should be noted that these impact levels are found only on approximately 28% of the surface where operations were carried out. From the evidence gathered in this study, winching seems a less impactful extraction method in the studied context. On the other hand, to decrease the impact of forwarding, some technical adjustments such as bogie-tracks, as well as improved operator training, should be applied.
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Land 2022, 11, 388. https://doi.org/10.3390/land11030388 www.mdpi.com/journal/land
Article
Variations of Soil Physico-Chemical and Biological Features
after Logging Using Two Different Ground-Based Extraction
Methods in a Beech High Forest—A Case Study
Rachele Venanzi
1
, Francesco Latterini
2,
*, Walter Stefanoni
2
,
Damiano Tocci
1
and Rodolfo Picchio
1
1
Department of Agricultural and Forest Sciences, University of Tuscia, Via San Camillo de Lellis,
01100 Viterbo, Italy; venanzi@unitus.it (R.V.); tocci@unitus.it (D.T.); r.picchio@unitus.it (R.P.)
2
Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria (CREA), Centro di Ricerca
Ingegneria e Trasformazioni Agroalimentari, Via della Pascolare 16, 00015 Monterotondo, Italy;
walter.stefanoni@crea.gov.it
* Correspondence: francesco.latterini@crea.gov.it
Abstract: Considering that forests are crucial in the ecosystem of our planet and that forests provide
timber products as well as several ecosystem services, it is evident that the application of sustainable
forest operations (SFOs) is of substantial importance to achieve sustainable forest management
(SFM). One of the most important issues to be evaluated when dealing with SFOs is limiting the
disturbance and impacts related to logging. Harvesting activities can indeed alter the conditions of
soil through compaction and litter removal which can also lead to modifications from the biological
point of view, for example, diminishing the presence of soil microarthropods. While keeping these
objectives in focus, the aim of the present study was to evaluate physico-chemical and biological
impacts on forest soil in Mediterranean beech forests after forest logging with two different extrac-
tion systems, which are forestry-fitted farm tractors equipped with winch and forwarder. Specifi-
cally, authors aimed to investigate: i) soil disturbance levels of ground-based extraction methods;
ii) soil disturbance levels of the applied forestry intervention; iii) soil disturbance levels between
winching-skidding and forwarding. Findings showed that the physical, chemical, and biological
soil features were slightly disturbed by the forestry itself. In addition, forest operations and machine
traffic showed clear soil disturbance, resulting in a substantial alteration of the characteristics. Be-
tween the two extraction techniques tested, winching caused less disturbance while forwarding had
stronger impacts. However, it should be noted that these impact levels are found only on approxi-
mately 28% of the surface where operations were carried out. From the evidence gathered in this
study, winching seems a less impactful extraction method in the studied context. On the other hand,
to decrease the impact of forwarding, some technical adjustments such as bogie-tracks, as well as
improved operator training, should be applied.
Keywords: sustainable forest operations; sustainable forest management; QBS-ar index; winching;
forwarder
1. Introduction
Forests are crucial in the ecosystem of our planet. In fact, they provide not only tim-
ber products but also several ecosystem services [1] such as carbon balance, hydrological
protection, recreational opportunities and habitat provision [2–4]. To allow forests to per-
form their fundamental services, it is crucial to manage them properly by applying sus-
tainable forest management (SFM) [5]. When speaking of SFM, it is intended that this type
of management allows forests to maintain and enhance their economic, social and envi-
ronmental value for the benefit of present and future generations [6].
Citation: Venanzi, R.; Latterini, F.;
Stefanoni, W.; Tocci, D.; Picchio, R.
Variations of Soil Physico-Chemical
and Biological Features after Log-
ging Using Two Different Ground-
Based Extraction Methods in a Beech
High Forest—A Case Study. Land
2022, 11, 388. https://
doi.org/10.3390/land11030388
Academic Editor: Cezary Kabala
Received: 15 February 2022
Accepted: 4 March 2022
Published: 5 March 2022
Publisher’s Note: MDPI stays
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Copyright: © 2022 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
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Attribution (CC BY) license
(https://creativecommons.org/license
s/by/4.0/).
Land 2022, 11, 388 2 of 15
Several approaches and behaviors can be helpful to achieve SFM. Among these are
innovating silvicultural treatments [7], valorizing residues through the development of
innovative by-products [8] and adopting close-to-nature silviculture [9]. Another benefi-
cial and fundamental approach in this context is developing sustainable forest operations
(SFOs). This means practicing forest logging in a way that ensures high productivity and
low costs (economic pillar), reduced impact on the environment referred to as the envi-
ronmental pillar and safe working conditions for the operators that is the social pillar
[10,11].
The application of SFOs is particularly necessary to achieve SFM. Without sustaina-
ble forest utilization, it is impossible to guarantee the health of the forest ecosystem
[12,13].
One of the main issues when putting SFOs into practice is limiting the impact on
forest soil caused by logging [14]. Soil compaction because of forest operations that can
lead to hydrological issues of increased runoff and sediment yield [15,16], including the
improper development of natural regeneration with decreased seedling biomass and root
length [17].
Several studies have been conducted to evaluate such impacts, and there is a wide
range of literature on the topic [18,19]. The evaluation of the implications of different sil-
vicultural practices and harvesting methods on forest soil has been one of the most im-
portant research topics in the sector of forest engineering since the 1980s [20–23].
Nonetheless, there is still much to investigate regarding the issue of soil impacts re-
lated to forest logging. Indeed, the major part of the current literature is focused on conif-
erous stands, considering the generally higher economic importance of this type of forest.
Furthermore, while the implications of logging on physico-chemical soil properties have
been widely investigated, only a few studies focused on impacts to soil biological features
[24]. For example, using the QBS-ar index (soil biological quality index based on microar-
thropods) has shown very interesting features as an indicator of impacts on soil edaphic
fauna after logging [25,26].
Finally, few studies [27–29] have been reported in the literature regarding the com-
parison of different harvesting systems working in the same conditions (studying the
same intervention in the same area to evaluate soil impacts related to the different ma-
chineries).
Regarding this topic, Allmann et al. [27] compared the impacts to soil bulk density
after logging with different forwarders and skidders in several soil conditions, highlight-
ing that different machines led to similar kinds of impact on soil physical features. Eroğlu
et al. [28] studied the impacts of three different extraction systems (cable yarder, skidder
and chute system) in a spruce forest in Turkey. These reported higher impacts in the
ground-based extraction via skidder in comparison to the other systems. Some years later
Picchio et al. [29] evaluated three different extraction systems (cable yarder, forestry fitted
farm tractor, with winch and horse) concerning physico-chemical and biological impacts
after a strip clear cut in a pine stand, reporting the lowest impact for cable yarder and
tractor with winch.
Among the studies reported above [27–29], no one focused on hardwood species
managed as high forest and treated with the shelterwood system. This may be due to the
fact of the higher economic importance that softwood stands are currently showing. How-
ever, the climate change scenarios forecast for the following decades predict a substantial
impact of global warming on coniferous species. A consequent increased attention toward
the silviculture of hardwood species for silvicultural issues is expected, especially regard-
ing beech (Fagus sylvatica L.) [30,31].
On the other hand, there is still much to do regarding the deep understanding of
impacts related to logging in beech stands, mostly regarding biological issues in European
forests [18].
Land 2022, 11, 388 3 of 15
Indeed, several studies have been conducted to assess forest utilization impacts on
soil in beech forests, but the major part of these has been carried out outside Europe with-
out taking into consideration soil biological features [16,32,33]. Furthermore, very little
attention has been given to the evaluation of the impact on forest soil in beech stands of
cut-to-length (CTL) machineries, as forwarders, except for one study dated 2003 referring
to data from 1989–1991 [34].
This last mentioned is a very important aspect considering that in the last few years
CTL machineries have been introduced in hardwood stands. Until recently this system
was exclusively used in softwood stands, mostly in the Mediterranean context. Obviously,
there is still much to investigate in the application of CTL machineries in a sustainable
way in hardwood stands [35–38].
Considering all the literature, the objective of this study was to evaluate the physico-
chemical and biological impact on the forest soil in Mediterranean beech forests, because
of forest logging with two different extraction systems, which are forestry-fitted farm trac-
tors equipped with winch and forwarder.
There are several innovative aspects in this study. First, this is the first work that
considered the impact on soil fauna in beech forests. Second, this is the first comparative
study between the winching-skidding method and forwarding in this type of stand. Fi-
nally, this represents the first evaluation of soil impact after ground-based extraction to
beech stands carried out in the Mediterranean context. The research was developed fol-
lowing the methodology proposed in scientific studies on the same topic and highlighted
also by Picchio et al. [18].
The research hypothesis supported by the standardized experimental design can be
summarized as: i) the ground-based extraction system has a significant impact on soil
physico-chemical and biological properties with a short time perspective; ii) the impact
related to forestry is lower than the one triggered by forest logging. Moreover, a further
question for research is as follows: which is the most soil friendly ground-based logging
method in similar conditions, winching-skidding or forwarding?
2. Materials and Methods
2.1. Study Area
The study area is located on Mount Amiata in the region of Tuscany in Italy (coordi-
nate in WGS84UTM32T 713319 E; 4750291 N). It consists of two different subcompart-
ments of the forest management plan of the Forest Consortium of Amiata, a public entity
that manages all the public forests of the district of Grosseto, which includes Mount
Amiata and some private ones. Both subcompartments are even-aged beech stands man-
aged as high forest and treated as shelterwood systems (Figure 1). In both parcels the
intervention consisted of a late thinning from below carried out throughout the entire sur-
face of the subcompartment. Along with beech, there is the sporadic presence of silver fir
(Abies alba Mill.), sweet chestnut (Castanea sativa Mill.) and wild cherry (Prunus avium L.).
Soil texture is the same in both parcels, and the soil can be classified as sandy loam. Topo-
graphic features are also the same in the two subcompartments, with limited roughness
and medium slope (prevalent slope 28%).
Land 2022, 11, 388 4 of 15
Figure 1. Study area. The boundaries of the two subcompartments are reported in red. The parcel
extracted with a forwarder has yellow lines, while the one in which extraction was performed via
winching has light blue lines. In the figure the existing road network before harvesting is shown.
Blue line is for the main road, and the orange line is for the existing skid trails.
Both stands underwent the same type of intervention. The stands were also very close
in age: one stand was 102 years, and the other was 106 years. The preintervention average
dbh (diameter at breast height) was 45 cm, average height 26.6 m, stand density 149 n°
ha1 and standing volume 311.010 m3 ha1 in both parcels. Harvested volume was also very
similar, accounting for about 25% of the standing volume in both subcompartments.
The two subcompartments were both harvested in 2020 by forest operators with sim-
ilar working experience (> 15 years). Felling and processing were carried out in both sub-
compartments in a motor-manual way by chainsaw. Extraction operations were per-
formed with different systems. The CTL extraction system was performed by a forwarder
(FORW) in the subcompartment n. 3, while in the subcompartment n. 6 ,the tree length
system (TLS) was applied by a forestry-fitted farm tractor equipped with forest winch
(WINCH). These systems represent the most applied harvesting machineries for logging
activities in Mediterranean beech forests [36,39]. Indeed, while until some years ago
winching was practically the only option for forestry interventions in beech high forests,
in the last years there has been a growing application of forwarders [40]. Technical char-
acteristics of the applied machineries are reported in Table 1.
Table 1. Technical features of the applied machineries for WINCH and FORW experimental treat-
ments and main average operative data (±SD).
Parameter WINCH FORW
Machine type Forestry-fitted farm tractor Forwarder
Machine model Landini 135DT John Deere 1110D
Engine power 98 kW 120 kW
Land 2022, 11, 388 5 of 15
Equipment 60 kN Schwarz EGV 60 forest
winch n.a.
Empty weight 6
,
400 kg 15,370 kg
Average load for cycle 1,580.9±237.6 kg 10,411.7±729.4 kg
Average distance for cycle 195.8±7.7 m 273.9±10.1 m
Two different areas were identified in each subcompartment. The disturbed area
(DIST) consisted of all the forest surface directly affected by logging activities, which were
skid trails, strip roads and winching corridors. The undisturbed area (UND) was repre-
sented by the soil affected only by the silvicultural activity for instance the logging gaps
without winching corridors. Moreover, a third area used as control (CON) was identified.
This was a forest close to the two subcompartments, which in this case were properly
adjacent and with the same topography, soil and stand features. No harvesting operations
had not been carried out in this area in the last 30 years. This approach allowed us to
separately evaluate the impacts related to the silviculture treatment in itself (UND) with
the impacts caused by the proper forest operations (DIST). All the parameters mentioned
below were properly evaluated by considering this experimental design.
2.2. Investigated Variables
First, the assessment of the percentage of soil affected by the utilization was carried
out for both FORW and WINCH. To perform this evaluation six linear transects were es-
tablished in each subcompartment. Each transect was rectangular in shape (1 m × 200 m)
and defined using a compass and tape measure. Along the transect, visual inspection was
conducted for the presence or absence of bent understory, crushed litter, ruts, or soil mix-
ing and was applied to discriminate between disturbed soil and undisturbed soil. Data
were subsequently referred as the percentage of disturbed soil on the overall surface of
the transect.
The impact on the soil was evaluated on six randomly selected sample plots per treat-
ment (FORW-DIST; FORW-UND; WINCH-DIST; WINCH-UND; CON). Sample plots
consisted of circular areas of a 15 m radius, totaling a surface of 706.5 m2. The parameters
investigated of the soil physico-chemical properties were penetration resistance (PR),
shear resistance (SR), bulk density (BD) and organic matter (OM). Biological impacts were
assessed applying the QBS-ar index. The field survey was carried out in June 2021, about
one year after the end of the harvesting operations in both parcels.
2.3. Soil Physico-Chemical Properties
PR (MPa) and SR (Mg m2) were evaluated by a handheld dedicated instrument in
the first 3-10 cm of soil. Obtained values for PR and SR were referred to the soil water-
holding capacity as suggested by Saxton et al. [41]. For both PR and SR 18, measurements
were taken in each experimental treatment and six measurements in the control zone.
BD (g cm3) were assessed by sampling the soil with a dedicated corer (18 soil samples
in each experimental treatment and six samples in the control area). Then soil samples
were sealed in plastic bags and shipped to the laboratory for weighing after oven drying
at 105 °C to constant weight (dry weight). The dry weight divided by the volume of the
cylinder (100 cm3) gives the BD [42].
Organic matter (OM, %) evaluation was carried out by collecting 12 soil samples in
each experimental treatment and six in the control area. Each sample was collected with
the same corer applied for bulk density, put into a plastic bag and shipped to the labora-
tory. OM assessment was carried out with the incineration method in a mitten at 400 °C
for 4 h, after eliminating all the water with a pretreatment at 160 °C for 6 h [43].
2.4. QBS-ar Index Evaluation
Land 2022, 11, 388 6 of 15
Regarding biological impacts, the QBS-ar index was applied. This is a qualitative in-
dex that evaluates the complexity of the soil microarthropod community.
This index is based on the concept that the higher the soil quality, the higher the
number of microarthropod groups present as they are adapted to the soil environment.
Soil microarthropods are separated into several biological forms according to their mor-
phological adaptation to soil habitats. Each form is linked with a score named EMI (eco-
morphological index), that ranges from 1 to 20 in proportion to the degree of adaptation
[43]. The QBS-ar index value is the sum of the EMI of all found groups. To assess the QBS-
ar index, three soil cores 100 cm2 and 10 cm deep were sampled with a dedicated corer in
each area. Subsequently, microarthropods were extracted with a Berlese–Tüllgren funnel.
The various specimens were collected in a preserving solution (75% ethyl alcohol and 25%
glycerol by volume) and identified with different taxonomic levels (class for Myriapoda
and order for Insecta, Chelicerata and Crustacea) using a stereo microscope.
2.5. Statistical Analysis
After checking for data normality (Shapiro–Willk test) [44] and homoscedasticity
(Levene test) [45], the presence of statistically significant differences among the mean val-
ues of treatments was investigated with unpaired samples T-test (for the percentage of
impacted surface) [46] and one-way analysis of variance (ANOVA, for the other investi-
gated variables) [47]. An HSD Tukey test was applied post hoc [48]. Data which did not
show normal distribution, or which presented insufficient homogeneity of variance, were
statistically processed using the nonparametric ANOVA Kruskal–Wallis test [49] apply-
ing the Duncan test [50] post hoc. Furthermore, a principal component analysis (PCA)
[51] was performed to investigate any linear correlations between the treatments. To min-
imize the scaling effect because of different measurement units, the data of each independ-
ent variable were standardized using box-cox transformation.
Statistical analysis was carried out with Statsoft Statistica 7.0 (Statsoft, Tulsa, USA)
[52] and PAST software [53].
3. Results and Discussions
Both extraction systems led to a similar percentage of impacted surface (Figure 2). In
detail, ground-based operations via winching and forwarding impacted about 28% of the
overall surface, with values in line with similar systems applied in different conditions
[25,54,55]. The low tree density of the investigated stands did not lead to a lower percent-
age of impacted surface. This was rather expected for the forwarder, considering the short
working distance of this system, i.e., 10–12 m [36], forces the operator to extensively drive
the machine along the stand. On the contrary, winching in the presence of a stand with
low density (around 100 trees per hectare after the intervention) would assume a lower
impacted surface, considering the possibility of winching on longer distances. It is proba-
ble that the obtained results, which do not confirm this assertion, are related to the limited
application of snatch blocks which are effective solutions to reduce tree and soil damages
during winching [56]. These results therefore suggest the importance of the application of
best management practices during forest operations, considering that these are effective
solutions to mitigate the negative impact of logging [57–59].
Land 2022, 11, 388 7 of 15
Figure 2. Percentage of impacted surface with the two analyzed extraction systems. No statistically
significant difference was detected according unpaired samples T-test (p < 0.05). FORW: extraction
with forwarder; WINCH: extraction with forestry-fitted farm tractor equipped with winch.
Data on soil bulk density in the different treatments are given in Figure 3. Note that
BD is higher than CON for both disturbed and undisturbed soil for both extraction sys-
tems. Soil affected by forwarder passage (FORW-DIST) showed higher bulk density than
WINCH-DIST, suggesting a higher impact related to the CTL machinery on soil bulk den-
sity. On the other hand, as expected, no difference was revealed between the two UND
soil portions, considering that the silviculture treatment and the magnitude of interven-
tion and canopy removal was the same for the two investigated forest subcompartments.
Impact level in UND soil is indeed related to the degree of canopy cover removal [60,61].
Focusing on the comparison between the two applied extraction systems, it is possi-
ble to assert that obtained results are consistent with what was reported by Venanzi et al.
[62] concerning a comparison of soil impact related to winching and forwarding in a Med-
iterranean turkey oak (Quercus cerris L.) coppice. Authors of this publication revealed a
higher increase in soil bulk density triggered by forwarding operations compared to ex-
traction by winching-skidding. On the other hand, the obtained findings are not consistent
with the common assertion that an advanced mechanization level leads to decreased im-
pact on the soil. Therefore, it can be speculated that the lower impact reported in current
literature for machinery specifically dedicated to forestry [14] could be related more to the
correct application of specific tools to decrease soil damage that is caused by the tires of
the forwarders, for instance bogie tracks [12,26]. Without such specific adjustments, the
higher number of passages per volume unit needed to extract timber with the CTL system
in comparison to the TLS system seems to lead to higher soil disturbance.
Surprisingly, the magnitude of machinery-induced soil compaction found in this
study is three times higher than CON values for both WINCH and FORW, which is higher
than what was reported in current literature. Indeed, a recent meta-analysis on the topic
revealed an average increase in bulk density after forest utilization of 5–15% [63], while a
previous study carried out in Iran on oriental beech stands reported an average increase
of 19–39% [64]. This suggests a high sensitivity of the soil of the Mediterranean beech
forests to ground-based extraction, which should be evaluated carefully in future studies
along with an evaluation of the time needed for recovery.
Land 2022, 11, 388 8 of 15
Figure 3. BD for the different treatments. Different letters indicate different homogeneous group
according to an HSD Tukey test (p<0.05): CON: control area; WINCH: winching; FORW: forward-
ing; DIST: soil directly affected by machineries’ passage; UND: soil in the harvested parcels but not
directly affected by machineries’ passage.
Data on PR and SR are reported in Figure 4. The obtained results suggest a significant
impact related to forest utilisation for both variables, but not an influence because of sil-
vicultural activities. Indeed, regarding PR, FORW-DIST and WINCH-DIST were signifi-
cantly higher than CON with no difference between them. Concerning SR, FORW-DIST
was significantly higher than CON, while no difference was detected for WINCH-DIST.
From these results it can be speculated that there is a rather clear impact on both PR and
SR related to forest utilization, and the magnitude of this impact is not related to the ap-
plied machinery. Interestingly, no impact related to the silviculture in itself was detected
for both WINCH-UND and FORW-UND, which is consistent with what was reported in
a recent similar study carried out in a different kind of stand [62].
Figure 4. PR (a) and SR (b) for the different treatments. Different letters indicate different homoge-
neous group according to an HSD Tukey test (p < 0.05): CON: control area; WINCH: winching;
FORW: forwarding; DIST: soil directly affected by machineries’ passage; UND: soil in the harvested
parcels but not directly affected by machineries’ passage.
Land 2022, 11, 388 9 of 15
Interesting results were also obtained concerning OM (Figure 5). A significant impact
of forest utilization was revealed for both winching and forwarding. Furthermore, FORW-
DIST values were significantly lower than WINCH-DIST ones, suggesting that a higher
impact on soil OM occurred in the extraction via forwarder, as found by Venanzi et al.
[62], but different from what was reported by another similar study carried out on chest-
nut (Castanea sativa Mill.) coppice [26]. Regarding OM, silviculture in itself caused a sig-
nificant impact. Indeed, both WINCH-UND and FORW-UND showed lower values than
CON (with no differences between them as expected). From the obtained results it seems
that also the limited canopy gaps created by thinning interventions can lead to a decreased
soil OM in the first year after harvesting.
Figure 5. OM for the different treatments. Different letters indicate different homogeneous groups
according to an HSD Tukey test (p<0.05): CON: control area; WINCH: winching; FORW: forward-
ing; DIST: soil directly affected by machineries’ passage; UND: soil in the harvested parcels but not
directly affected by machineries’ passage.
Data on the impact on soil biological features are given in Figure 6. As is shown, only
WINCH-DIST had a significant impact in comparison to CON. A trend can therefore be
observed which is inverse to what is seen for the major part of the other parameters ana-
lyzed in the present study. Interestingly, and in contrast with similar studies carried out
with the same methodology but in different kinds of stands in the Mediterranean area
[25,26,62], silviculture in itself does not lead in the short-term to a decrease in the biodi-
versity of soil edaphic fauna, and WINCH-UND and FORW-UND values are not different
from CON. This could be related to the low litter decomposition rate typical of beech
[65,66], along with the fact that the studied stands were not affected by interventions at
least for 40 years before the harvesting intervention. This led to the creation of a thick layer
of litter, which acted as a sort of protective buffer, limiting the amount of light radiation
reaching the soil and thus decreasing the disturbance to soil edaphic fauna. Obviously,
further dedicated studies are needed to confirm this hypothesis and to assess its validity
with a longer time perspective.
Land 2022, 11, 388 10 of 15
Figure 6. QBS-ar index values for the different treatments. Different letters indicate different homo-
geneous group according to the Duncan test (p<0.05): CON: control area; WINCH: winching;
FORW: forwarding; DIST: soil directly affected by machineries’ passage; UND: soil in the harvested
parcels but not directly affected by machineries’ passage.
Focusing on an overview of the data found, Figure 7 shows the results of the principal
Ccmponents analysis (PCA) to summarize the findings obtained in a comprehensive
graphical framework. The two principal components PC1 and PC2 explained 48% and
26% of the total variance, respectively. It is evident how the undisturbed areas are close
to the control one, while disturbed zones are more distant, thus highlighting a higher im-
pact on the soil features. Moreover, the distance from the CON as compared to the
WINCH-DIST, showed that FORW-DIST had a greater impact.
Figure 7. Score plot of components PC1 and PC2 of the principal component analysis referred to the
investigated soil variables. Control area is reported in green; WINCH-UND in light blue; FORW-
Land 2022, 11, 388 11 of 15
UND in dark blue; WINCH-DIST in dark red and FORW-DIST in light red. Green lines indicate the
Biplot.
To summarize, this was the first study aimed at evaluating in the short-term the im-
pact triggered by two different harvesting systems in Mediterranean beech forests, focus-
ing on both physico-chemical and biological disturbances. The applied experimental de-
sign allowed for the separate assessment of the impact related to the applied machineries
(DIST soil) and of the ones related to forestry (UND soil). The first aspect which is worth
highlighting is that the impacts related to forestry are much lower than the ones related
to forest operations. The disturbance in UND soil was indeed evident for bulk density and
organic matter but not for penetration resistance, shear resistance and, interestingly, for
QBS-ar index. Focusing on the comparison between the two applied harvesting systems,
winching with a forestry-fitted farm tractor showed the ability to trigger lower disturb-
ance than forwarding. This statement is rather in contrast with current literature on the
topic [14], which suggests that machinery specifically developed for forest operations are
less impactful than adapted agriculture machinery. Instead, in the present study forward-
ing resulted in more impact than winching, particularly concerning increased bulk den-
sity and organic matter depletion. In this specific case, the difference can be attributed to
two factors. First, the CTL system applied with the forwarder needs more passages to
extract the same volume of material [67], thus triggering higher soil compaction [63]. Sec-
ond, the application of CTL machineries, such as forwarders, in Mediterranean forestry
has been growing extensively only in the last few years [36]. Therefore, operators could
be still not be fully skilled with the proper application of these machineries, as well as
with the technical adjustments which can decrease soil damages (such as, for example, the
application of bogie tracks or the placement of logging residues on the strip roads to de-
crease soil compaction) [12]. This highlights the need of increasing operators’ skills con-
cerning these modern machineries in Mediterranean context, suggesting the importance
of the collaboration between forest researchers, technicians and operators, in implement-
ing effective sustainable forest management [68,69].
4. Conclusions
Research conducted on this topic is of great interest. Findings give a precious insight
into the topic of “forest harvesting best practices”. The increase in knowledge for better
sustainable forest management supports the decision making of managers and stakehold-
ers. This is of particular importance when dealing with alterations to soil features that are
related to logging activities, which are defined as soil disturbances or soil impacts.
The data acquired from these case studies are important for updating meta-analysis
research, guidelines, criteria and indicators for SFOs applications.
As found in other studies, the physical, chemical, and biological soil features were
slightly disturbed by the forestry itself, as expected from continuous forest-cover silvicul-
ture. Forest operations and machine traffic showed clear disturbance through the mechan-
ical action on the soil structure, resulting in a substantial alteration to the soil characteris-
tics.
Between the two extraction techniques observed, winching caused lower disturbance
while forwarding had stronger impacts. This result is probably related to the different
applied harvesting systems, TLS and CTL, with the need for CTL to make more passages
per unit of volume. TLS application via winching seems therefore a solution able to trigger
lower disturbance to soil in the short-term. On the other hand, to increase the sustainabil-
ity of forwarding in Mediterranean beech forests, applying bogie-tracks and increasing
operator training could be possible solutions.
However, it should be noted that these impact levels are found, for both machineries,
on approximately 28% of the surface. Furthermore, although short-term impacts are sub-
stantial for both systems, data from the literature suggests a recovery time that should not
last longer than 5–8 years. However, further research is needed to test this hypothesis.
Land 2022, 11, 388 12 of 15
Abbreviations
BD: bulk density
CON: control area
CTL: cut-to-length harvesting system
DIST: disturbed soil (affected by machinery’s passage)
EMI: eco-morphological index
FORW: forwarder
OM: organic matter
PR: penetration resistance
QBS-ar: soil biological quality index based on microarthropods
SFM: sustainable forest management
SFOs: sustainable forest operations
SR: shear resistance
TLS: tree length harvesting system
UND: undisturbed soil (soil in the harvested parcel but not directly affected by the pas-
sage of machineries)
WINCH: forestry fitted farm tractor equipped with winch
Author Contributions: Conceptualization, F.L., R.V. and R.P.; methodology, F.L., R.V., D.T., W.S.
and R.P.; formal analysis, F.L. and R.P.; writing—original draft preparation, F.L., R.V., D.T. and
W.S.; writing—review and editing, F.L., R.V., W.S. and R.P.; supervision, R.P. All authors have read
and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Acknowledgments: The authors gratefully acknowledge Forest Consortium of Amiata, Arcidosso
– Italy. This research was in part carried out within the framework of the MIUR (Italian Ministry for
Education, University and Research) initiative “Departments of Excellence” (Law 232/2016), WP3,
which financed the Department of Agriculture and Forest Science at the University of Tuscia. This
research was in part carried out within the project PLANNING CHANGE (CAMBIO PIANO), PSR
2014-2020 Tuscany Region, met. Leader. Meas. 16.2 – Gal F.A.R. Maremma.
Data Availability Statement: Not applicable.
Informed Consent Statement: Not applicable
Data Availability Statement: The data presented in this study are available on request from the
corresponding author.
Conflicts of Interest: The authors declare no conflict of interest.
References
1. Simons, N.K.; Felipe-Lucia, M.R.; Schall, P.; Ammer, C.; Bauhus, J.; Blüthgen, N.; Boch, S.; Buscot, F.; Fischer, M.; Goldmann,
K.; et al. National Forest Inventories capture the multifunctionality of managed forests in Germany. For. Ecosyst. 2021, 8, 5.
https://doi.org/10.1186/s40663-021-00280-5.
2. Gamfeldt, L.; Snäll, T.; Bagchi, R.; Jonsson, M.; Gustafsson, L.; Kjellander, P.; Ruiz-Jaen, M.C.; Fröberg, M.; Stendahl, J.; Philip-
son, C.D.; et al. Higher levels of multiple ecosystem services are found in forests with more tree species. Nat. Commun. 2013, 4,
1340. https://doi.org/10.1038/ncomms2328.
3. Miura, S.; Amacher, M.; Hofer, T.; San-Miguel-Ayanz, J.; Ernawati; Thackway, R. Protective functions and ecosystem services
of global forests in the past quarter-century. For. Ecol. Manag. 2015, 352, 35–46. https://doi.org/10.1016/j.foreco.2015.03.039.
4. Fitts, L.A.; Russell, M.B.; Domke, G.M.; Knight, J.K. Modeling land use change and forest carbon stock changes in temperate
forests in the United States. Carbon Balance Manag. 2021, 16, 20. https://doi.org/10.1186/s13021-021-00183-6.
5. Soler, R.; Lorenzo, C.; González, J.; Carboni, L.; Delgado, J.; Díaz, M.; Toro Manríquez, M.D.R.; Alejandro, H.H. The politics
behind scientific knowledge: Sustainable forest management in Latin America. For. Policy Econ. 2021, 131, 102543.
https://doi.org/10.1016/j.forpol.2021.102543.
6. FAO; UNEP. The State of the World’s Forests 2020: Forests, Biodiversity and People; FAO: Rome, Italy, 2020.
7. Salvati, L.; Becagli, C.; Bertini, G.; Cantiani, P.; Ferrara, C.; Fabbio, G. Toward sustainable forest management indicators? A data mining
approach to evaluate the impact of silvicultural practices on stand structure. Int. J. Sustain. Dev. World Ecol. 2017, 24, 372–382.
Land 2022, 11, 388 13 of 15
8. Janiszewska, D.; Olchowski, R.; Nowicka, A.; Zborowska, M.; Marszałkiewicz, K.; Shams, M.; Giannakoudakis, D.A.; Anasto-
poulos, I.; Barczak, M. Activated biochars derived from wood biomass liquefaction residues for effective removal of hazardous
hexavalent chromium from aquatic environments. GCB Bioenergy 2021, 13, 1247–1259. https://doi.org/10.1111/gcbb.12839.
9. Schneider, R.; Franceschini, T.; Duchateau, E.; Bérubé-Deschênes, A.; Dupont-Leduc, L.; Proudfoot, S.; Power, H.; de Coligny,
F. Influencing plantation stand structure through close-to-nature silviculture. Eur. J. For. Res. 2021, 140, 567–587.
https://doi.org/10.1007/s10342-020-01349-6.
10. Marchi, E.; Chung, W.; Visser, R.; Abbas, D.; Nordfjell, T.; Mederski, P.S.; McEwan, A.; Brink, M.; Laschi, A. Sustainable Forest
Operations (SFO): A new paradigm in a changing world and climate. Sci. Total Environ. 2018, 634, 1385–1397.
https://doi.org/10.1016/j.scitotenv.2018.04.084.
11. Sohrabi, H.; Jourgholami, M.; Jafari, M.; Shabanian, N.; Venanzi, R.; Tavankar, F.; Picchio, R. Soil recovery assessment after timber
harvesting based on the Sustainable Forest Operation (SFO) perspective in Iranian temperate forests. Sustainability 2020, 12, 2874.
12. Labelle, E.R.; Hansson, L.; Högbom, L.; Jourgholami, M.; Laschi, A. Strategies to Mitigate the Effects of Soil Physical Disturbances
Caused by Forest Machinery: A Comprehensive Review. Curr. For. Rep. 2022, 8, 20–37. https://doi.org/10.1007/s40725-021-00155-6.
13. Holzfeind, T.; Visser, R.; Chung, W.; Holzleitner, F.; Erber, G. Development and Benefits of Winch-Assist Harvesting. Curr. For.
Rep. 2020, 6, 201–209. https://doi.org/10.1007/s40725-020-00121-8.
14. Hoffmann, S.; Schönauer, M.; Heppelmann, J.; Asikainen, A.; Cacot, E.; Eberhard, B.; Hasenauer, H.; Ivanovs, J.; Jaeger, D.;
Lazdins, A.; et al. Trafficability Prediction Using Depth-to-Water Maps: The Status of Application in Northern and Central
European Forestry. Curr. For. Rep. 2022, 8, 55–71. https://doi.org/10.1007/s40725-021-00153-8.
15. Picchio, R.; Jourgholami, M.; Zenner, E.K. Effects of Forest Harvesting on Water and Sediment Yields: A Review Toward Better
Mitigation and Rehabilitation Strategies. Curr. For. Rep. 2021, 7, 214–219.
16. Jourgholami, M.; Khoramizadeh, A.; Venanzi, R.; Latterini, F.; Tavankar, F.; Picchio, R. Evaluation of Leaf Litter Mulching and
Incorporation on Skid Trails for the Recovery of Soil Physico-Chemical and Biological Properties of Mixed Broadleaved Forests.
Land 2021, 10, 625. https://doi.org/10.3390/land10060625.
17. Mariotti, B.; Hoshika, Y.; Cambi, M.; Marra, E.; Feng, Z.; Paoletti, E.; Marchi, E. Vehicle-induced compaction of forest soil affects
plant morphological and physiological attributes: A meta-analysis. For. Ecol. Manag. 2020, 462, 118004.
https://doi.org/10.1016/j.foreco.2020.118004.
18. Picchio, R.; Mederski, P.S.; Tavankar, F. How and How Much, Do Harvesting Activities Affect Forest Soil, Regeneration and
Stands? Curr. For. Rep. 2020, 6, 115–128. https://doi.org/10.1007/s40725-020-00113-8.
19. Schweier, J.; Magagnotti, N.; Labelle, E.R.; Athanassiadis, D. Sustainability Impact Assessment of Forest Operations: A Review.
Curr. For. Rep. 2019, 5, 101–113. https://doi.org/10.1007/s40725-019-00091-6.
20. Miller, J.H.; Sirois, D.L. Soil Disturbance by Skyline Yarding vs. Skidding in a Loamy Hill Forest. Soil Sci. Soc. Am. J. 1986, 50,
1579–1583. https://doi.org/10.2136/sssaj1986.03615995005000060039x.
21. Rab, M.A. Soil physical and hydrological properties following logging and slash burning in the Eucalyptus regnuns forest of
southeastern Australia. For. Ecol. Manag. 1996, 84, 159–176.
22. Whitman, A.A.; Brokaw, N.V.L.; Hagan, J.M. Forest damage caused by selection logging of mahogany (Swietenia macrophylla)
in northern Belize. For. Ecol. Manag. 1997, 92, 87–96. https://doi.org/10.1016/S0378-1127(96)03941-2.
23. Merino, A.; Edeso, J.M.; González, M.J.; Marauri, P. Soil properties in a hilly area following different harvesting management
practices. For. Ecol. Manag. 1998, 103, 235–246. https://doi.org/10.1016/S0378-1127(97)00229-6.
24. Elie, F.; Vincenot, L.; Berthe, T.; Quibel, E.; Zeller, B.; Saint-André, L.; Normand, M.; Chauvat, M.; Aubert, M. Soil fauna as bioindi-
cators of organic matter export in temperate forests. For. Ecol. Manag. 2018, 429, 549–557. https://doi.org/10.1016/j.foreco.2018.07.053.
25. Venanzi, R.; Picchio, R.; Grigolato, S.; Latterini, F. Soil and forest regeneration after different extraction methods in coppice
forests. For. Ecol. Manag. 2019, 454, 117666. https://doi.org/10.1016/j.foreco.2019.117666.
26. Venanzi, R.; Picchio, R.; Grigolato, S.; Spinelli, R. Soil Disturbance Induced by Silvicultural Treatment in Chestnut (Castanea
sativa Mill.) Coppice and Post-Disturbance Recovery. Forests 2020, 11, 1053. https://doi.org/10.3390/f11101053.
27. Allman, M.; Jankovský, M.; Messingerová, V.; Allmanová, Z.; Ferenčík, M. Soil compaction of various Central European forest soils
caused by traffic of forestry machines with various chassis. For. Syst. 2015, 24, e038. https://doi.org/10.5424/fs/2015243-07541.
28. Eroğlu, H.; Sariyildiz, T.; Küçük, M.; Sancal, E. The effects of different logging techniques on the physical and chemical charac-
teristics of forest soil. Balt. For. 2016, 22, 139–147.
29. Picchio, R.; Mercurio, R.; Venanzi, R.; Gratani, L.; Giallonardo, T.; Lo Monaco, A.; Frattaroli, A.R. Strip Clear-Cutting Applica-
tion and Logging Typologies for Renaturalization of Pine Afforestation—A Case Study. Forests 2018, 9, 366.
30. Dyderski, M.K.; Paź, S.; Frelich, L.E.; Jagodziński, A.M. How much does climate change threaten European forest tree species
distributions? Glob. Chang. Biol. 2018, 24, 1150–1163. https://doi.org/10.1111/gcb.13925.
31. Antonucci, S.; Santopuoli, G.; Marchetti, M.; Tognetti, R.; Chiavetta, U.; Garfì, V. What Is Known About the Management of Euro-
pean Beech Forests Facing Climate Change? A Review. Curr. For. Rep. 2021, 7, 321–333. https://doi.org/10.1007/s40725-021-00149-4.
32. Tavankar, F.; Picchio, R.; Nikooy, M.; Jourgholami, M.; Naghdi, R.; Latterini, F.; Venanzi, R. Soil natural recovery process and
Fagus orientalis lipsky seedling growth after timber extraction by wheeled skidder. Land 2021, 10, 113.
https://doi.org/10.3390/land10020113.
33. Tavankar, F.; Bonyad, A.E.; Nikooy, M.; Picchio, R.; Venanzi, R.; Calienno, L. Damages to soil and tree species by cable-skidding
in Caspian forests of Iran. For. Syst. 2017, 26, 11.
Land 2022, 11, 388 14 of 15
34. Rohand, K.; Al Kalb, A.; Herbauts, J.; Verbrugge, J.C. Changes in some mechanical properties of a loamy soil under the influence of
mechanized forest exploitation in a beech forest of central Belgium. J. Terramech. 2003, 40, 235–253.
https://doi.org/10.1016/j.jterra.2003.12.004.
35. Labelle, E.; Breinig, L.; Sycheva, E. Exploring the Use of Harvesters in Large-Diameter Hardwood-Dominated Stands. Forests
2018, 9, 424. https://doi.org/10.3390/f9070424.
36. Picchio, R.; Latterini, F.; Mederski, P.S.; Tocci, D.; Venanzi, R.; Stefanoni, W.; Pari, L. Applications of GIS-Based Software to
Improve the Sustainability of a Forwarding Operation in Central Italy. Sustainability 2020, 12, 5716.
https://doi.org/10.3390/su12145716.
37. Bustos-Letelier, O.; Mena, C.; Bussenius, W.; Briceño, M. The Influence of Old and New Machines on Productivity and Costs of
Four Yarding Methods in Small-Scale Forestry in a Maine Forest. Small-Scale For. 2021, 20, 97–117.
38. Mederski, P.S.; Borz, S.A.; Đuka, A.; Lazdiņš, A. Challenges in forestry and forest engineering—Case studies from four countries
in East Europe. Croat. J. For. Eng. 2020, 42, 117–134. https://doi.org/10.5552/crojfe.2021.838.
39. Picchio, R.; Pignatti, G.; Marchi, E.; Latterini, F.; Benanchi, M.; Foderi, C.; Venanzi, R.; Verani, S. The Application of Two Ap-
proaches Using GIS Technology Implementation in Forest Road Network Planning in an Italian Mountain Setting. Forests 2018,
9, 277. https://doi.org/10.3390/f9050277.
40. Ursić, B.; Vusić, D.; Papa, I.; Poršinsky, T.; Zečić, Ž.; Ðuka, A. Damage to Residual Trees in Thinning of Broadleaf Stand by
Mechanised Harvesting System. Forests 2022, 13, 51. https://doi.org/10.3390/f13010051.
41. Saxton, K.E.; Rawls, W.; Romberger, J.S.; Papendick, R.I. Estimating generalized soil-water characteristics from texture. Soil Sci.
Soc. Am. J. 1986, 50, 1031–1036.
42. Marchi, E.; Picchio, R.; Mederski, P.S.; Vusić, D.; Perugini, M.; Venanzi, R. Impact of silvicultural treatment and forest operation
on soil and regeneration in Mediterranean Turkey oak (Quercus cerris L.) coppice with standards. Ecol. Eng. 2016, 95, 475–484.
43. Venanzi, R.; Picchio, R.; Piovesan, G. Silvicultural and logging impact on soil characteristics in Chestnut (Castanea sativa Mill.)
Mediterranean coppice. Ecol. Eng. 2016, 92, 82–89.
44. Shapiro, S.S.; Wilk, M.B. An analysis of variance test for normality (complete samples). Biometrika 1965, 52, 591–611.
45. Glass, G. V Testing homogeneity of variances. Am. Educ. Res. J. 1966, 3, 187–190.
46. Pfanzagl, J.; Sheynin, O. Studies in the history of probability and statistics XLIV A forerunner of the t-distribution. Biometrika
1996, 83, 891–898.
47. Fisher, R.A. The Correlation Between Relatives on the Supposition of Mendelian Inheritance. Philos. Trans. R. Soc. Edinb. 1918,
52, 399–433.
48. Tukey, J.W. Comparing individual means in the analysis of variance. Biometrics 1949, 5, 99–114.
49. Kruskal, W.H.; Wallis, W.A. Use of Ranks in One-Criterion Variance Analysis. J. Am. Stat. Assoc. 1952, 47, 583–621.
https://doi.org/10.1080/01621459.1952.10483441.
50. Duncan, D.B. Multiple range and multiple F tests. Biometrics 1955, 11, 1–42.
51. Pearson, K. LIII. On lines and planes of closest fit to systems of points in space. London, Edinburgh, Dublin Philos. Mag. J. Sci.
1901, 2, 559–572.
52. StatSoft, Inc. STATISTICA (Data Analysis Software System), Version 7.0. 2007. Available online: www.statsoft.com (accessed on
25 January 2022).
53. Hammer, Ø.; Harper, D.A.T.; Ryan, P.D. PAST: Paleontological statistics software package for education and data analysis.
Palaeontol. Electron. 2001, 4, 9.
54. Spinelli, R.; Magagnotti, N.; Nati, C. Benchmarking the impact of traditional small-scale logging systems used in Mediterranean
forestry. For. Ecol. Manag. 2010, 260, 1997–2001.
55. Jourgholami, M.; Majnounian, B.; Abari, M.E. Effects of tree-length timber skidding on soil compaction in the skid trail in Hyr-
canian forests. For. Syst. 2014, 23, 288–293. https://doi.org/10.5424/fs/2014232-03766.
56. Picchio, R.; Magagnotti, N.; Sirna, A.; Spinelli, R. Improved winching technique to reduce logging damage. Ecol. Eng. 2012, 47, 83–86.
57. Hawks, B.S.; Aust, W.M.; Bolding, M.C.; Barrett, S.M.; Schilling, E.; Fielding, J.A.H. Linkages between Forestry Best Management
Practices and erosion in the southeastern U.S. J. Environ. Manag. 2022, 305, 114411. https://doi.org/10.1016/j.jenvman.2021.114411.
58. Phelps, K.; Hiesl, P.; Hagan, D.; Hotaling Hagan, A. The Harvest Operability Index (HOI): A Decision Support Tool for Mech-
anized Timber Harvesting in Mountainous Terrain. Forests 2021, 12, 1307. https://doi.org/10.3390/f12101307.
59. Walsh, P.; Jakeman, A.; Thompson, C. The effects of selective timber harvesting in buffer strips along headwater channels using
best management practices on runoff, turbidity and suspended sediment yield in an intensively cut eucalypt forest in south-
eastern Australia. For. Ecol. Manag. 2020, 458, 117812. https://doi.org/10.1016/j.foreco.2019.117812.
60. Jourgholami, M.; Feghhi, J.; Tavankar, F.; Latterini, F.; Venanzi, R.; Picchio, R. Short-term effects in canopy gap area on the
recovery of compacted soil caused by forest harvesting in old-growth Oriental beech (Fagus orientalis Lipsky) stands. iForest
Biogeosci. For. 2021, 14, 370–377. https://doi.org/10.3832/ifor3432-014.
61. Amolikondori, A.; Abrari Vajari, K.; Feizian, M.; Di Iorio, A. Influences of forest gaps on soil physico-chemical and biological
properties in an oriental beech (Fagus orientalis L.) stand of Hyrcanian forest, north of Iran. iForest 2020, 13, 124–129.
https://doi.org/10.3832/ifor3205-013.
62. Venanzi, R.; Picchio, R.; Spinelli, R.; Grigolato, S. Soil Disturbance and Recovery after Coppicing a Mediterranean Oak Stand:
The Effects of Silviculture and Technology. Sustainability 2020, 12, 4074. https://doi.org/10.3390/su12104074.
Land 2022, 11, 388 15 of 15
63. Nazari, M.; Eteghadipour, M.; Zarebanadkouki, M.; Ghorbani, M.; Dippold, M.A.; Bilyera, N.; Zamanian, K. Impacts of Logging-As-
sociated Compaction on Forest Soils: A Meta-Analysis. Front. For. Glob. Chang. 2021, 4, 780074. https://doi.org/10.3389/ffgc.2021.780074.
64. Jaafari, A.; Najafi, A.; Zenner, E.K. Ground-based skidder traffic changes chemical soil properties in a mountainous Oriental
beech (Fagus orientalis Lipsky) forest in Iran. J. Terramech. 2014, 55, 39–46.
65. Wise, D.H.; Schaefer, M. Decomposition of leaf litter in a mull beech forest: Comparison between canopy and herbaceous spe-
cies. Pedobiologia 1994, 38, 269–288.
66. Sariyildiz, T. Effects of gap-size classes on long-term litter decomposition rates of beech, oak and chestnut species at high ele-
vations in northeast Turkey. Ecosystems 2008, 11, 841–853. https://doi.org/10.1007/s10021-008-9164-x.
67. Cambi, M.; Grigolato, S.; Neri, F.; Picchio, R.; Marchi, E. Effects of forwarder operation on soil physical characteristics: A case
study in the Italian alps. Croat. J. For. Eng. 2016, 37, 233–239.
68. Schwegman, K.; Spinelli, R.; Magagnotti, N.; Ramantswana, M.; McEwan, A. Selecting successful harvester operators through
aptitude tests and demographics. Aust. For. 2021, 84, 25–32.
69. Thiffault, N.; Raymond, P.; Lussier, J.-M.; Aubin, I.; Royer-Tardif, S.; D’Amato, A.W.; Doyon, F.; Lafleur, B.; Perron, M.;
Bousquet, J. Adaptive Silviculture for Climate Change: From Concepts to Reality Report on a symposium held at Carrefour
Forêts 2019. For. Chron. 2021, 97, 13–27.
... The more recent studies that focused on soil disturbance in Mediterranean beech forests were conducted by our research group. In a case study in Mount Amiata (Tuscany, Italy) we found strong soil compaction in the skid trails, with values of bulk density that increased by about 50 % in comparison to the soil which was not affected by the passage of a machine (Venanzi et al., 2022). Mechanical soil disturbance also led to decreased biodiversity of soil microarthropods in the skid trails, with a 22 % decrease in the QBS-ar (soil biological quality index based on the microarthropod biodiversity) (Venanzi et al., 2022). ...
... In a case study in Mount Amiata (Tuscany, Italy) we found strong soil compaction in the skid trails, with values of bulk density that increased by about 50 % in comparison to the soil which was not affected by the passage of a machine (Venanzi et al., 2022). Mechanical soil disturbance also led to decreased biodiversity of soil microarthropods in the skid trails, with a 22 % decrease in the QBS-ar (soil biological quality index based on the microarthropod biodiversity) (Venanzi et al., 2022). In another study done in beech forests, the short-term (less than two years after harvesting) soil disturbance caused by forest operations was assessed in different skid trails. ...
... However, the effect size for bulk density was only about +13 %, although it was significant (Latterini et al., 2023d). Similar effect sizes in terms of increased penetration resistance and shear resistance were also revealed in previous studies in Mount Amiata (Area 1), but in that case we found increased bulk density and decreased soil organic matter along the skid trails, in contrast to what happened in this research (Venanzi et al., 2022). However, this difference can be related to the fact that in the study of Venanzi et al. (2022), the focus of the research was also on primary skid trails, characterised by a higher number of machine passes. ...
Article
Full-text available
Despite the high ecological value of Mediterranean beech forests, very little is known about the implications of forest operations on soil microarthropod biodiversity and litter decomposition rate. There is also no information concerning the amount of time needed for disturbed forest soil to recover and return to the pre-harvesting conditions. Silvicultural treatments are scheduled about every ten to fifteen years, without taking into account the amount of time necessary for recovery. The purpose of this study was to determine this information. The study started by selecting three study sites located along the Italian Apennine, each including a chronosequence of three forest parcels: one harvested in 2021, one harvested in 2012, and a control parcel which had not been harvested within the last forty years. In the harvested parcels we investigated skid trails which are classified as disturbed, and soil not affected by the passage of a machine which is classified as undisturbed. Thus in each study area there were five experimental treatments including the control area. The soil physico-chemical properties were assessed for each treatment. These included bulk density, penetration resistance, shear resistance, organic matter content, and soil microarthropod biodiversity which was assessed by the QBS-ar index (Soil Biological Quality based on microarthropods, a qualitative index measuring the quality of soil according to the biodiversity of the microarthropod community). We further established a litter decomposition experiment, using teabags as reference material, to check the differences among treatments in litter decomposition rates. We used linear mixed-effects models to investigate the effects of the experimental treatment on the physico-chemical and biological features, and relationships among QBS-ar index and soil physico-chemical features. We analysed the effects of the experimental treatment on the litter decomposition rate using generalised linear-mixed effects models. A significant effect caused by machine passage was found in the recently harvested parcels on soil penetration resistance (~+70 % comparing to the control), shear resistance (~+35 %), and QBS-ar index (-25 %). Effects of machine passage on soil bulk density and organic matter content were not significant. All the investigated variables in the skid trails returned to values similar to those recorded in the control after ten years. We did not find effects of any soil physico-chemical features on QBS-ar index. Finally, no effect of the experimental treatment was found on the litter decomposition rate, suggesting that a stronger magnitude of soil 2 disturbance is needed to affect this complex biogeochemical process. Although the initial impact was highly significant, it was found that a 10-year period is sufficient for recovering the investigated soil features in the upper soil layer. This was observed in Mediterranean beech forests when forest operations were done with low-weight machines and a limited number of machine passes on the skid trails. Thus, it can be concluded that planning another operation 10-15 years after the previous thinning, as is currently done, remains in line with the time needed for the forest soil to recover.
... Apart from the direct effects of machinery traffic on soil compaction [27], the implications of forest operations have been investigated from different points of view, for instance, the effects on erosion and runoff [7] or on the morphological features of natural regeneration [110]. Several studies also highlighted the strong effects of soil compaction on the soil microarthropod community [111][112][113]. The effects of machinery traffic and subsequent soil compaction on litter decomposition rate have been much less investigated and this is a fundamental aspect of forest operations requiring a deeper recognition. ...
... However, it is evident that the topic of alteration of litter decomposition rate by soil disturbance as a consequence of ground-based forest operations should be further investigated in future studies. Indeed, given that machinery traffic on the forest soil is the major driver of disturbance to the soil edaphic communities [16], and that such disturbance can usually affect up to 30-35% of the overall area of the cutting block [113,117], it is fundamental to understand at a deeper level the influence of logging activities on the litter decomposition rate. Such a large proportion of the affected area cannot be neglected if we want to understand the complex process of litter decomposition and how it is related to active forest management. ...
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Purpose of Review As litter decomposition is a fundamental process in forest ecosystems, representing the link between aboveground and belowground biogeochemical processes, we developed an effect size summarisation of the implications of forest management on litter decomposition rate, by applying a multi-level meta-analysis and multivariate mixed-effects meta-analytic linear models. Our aim was to review the findings of the current literature and to understand how forest management, silvicultural treatment, and forest operations could affect litter decomposition rate. Furthermore, we investigated the effects of environmental variables that included stand type, climatic conditions, and the percentage of biomass removal on litter decomposition rate. Recent Findings We found a statistically significant reduction in litter decomposition rate associated with clear-cutting, and no statistically significant differences for the overall effects of retention forestry and logging activities (disturbed forest soil in the form of skid trails or strip roads). Concerning the sub-group analysis and multivariate meta-regression, there were no significant effects for stand type (broadleaf, coniferous, or mixed) or climatic conditions (mean annual temperature and annual precipitation). The percentage of biomass removal showed a significant positive correlation with the effect size, thus indicating that higher biomass removal in the framework of retention forestry leads to an increase in litter decomposition rate. Also, the mesh size of the litterbag showed a positive correlation with the effect size, suggesting that there is a probability of a factor of stronger disturbance to large-body decomposer organisms such as microarthropods. Summary Litter decomposition rate is related, among other factors, to soil microclimatic conditions and soil biota. Therefore, this process can be strongly influenced by active forest management, meant as a silvicultural treatment carried out by applying a given harvesting system. In the context of retention forestry, increased light availability seems to be the driving force in shaping increased litter decomposition rates with increasing biomass removal. On the other hand, when a clear-cut is applied, the stronger modification to the edaphic community leads to decreased litter decomposition rates. It is worth noting that the modification may also be related to soil manipulation to favour the establishment of artificial regeneration. The findings, however, showed very large variability, thus suggesting the need for further research on such a complex topic. Multidisciplinary studies that analyse the microclimate and the edaphic biological communities along with the litter decomposition are particularly recommended.
... A higher soil compaction related to forwarding (14 % higher than in skidding trails) did not reveal the same effect on the soil microarthropods community in an even-aged beech (Fagus sylvatica L.) high forest after a thinning from below intervention. The QBS-ar index did not show significant differences between forwarding and skidding trails, specifically 147 in forwarding and 139 in skidding (Venanzi et al., 2022). Concerning soil erosion studies, it was proved that both systems can cause increased runoff in the soil affected by the machine passage, with no substantial differences between the two systems (Wagenbrenner et al., 2016). ...
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The disturbance that ground-based extraction operations can imply on the forests ecosystem is an issue which demands more attention. Skidding and forwarding are the two most common ground-based extraction systems. While skidding implies to partially or fully dragging the logs on the ground, in forwarding, timber is transported on a deck thus avoiding direct contact with the soil. Generally, skidding is considered to be more impactful than forwarding in relation to the amount of disturbance on forest soil and residual stand. However, the framework depicted in current literature is not so strict. While skidding actually implies a higher level of damage to residual stand, the situation concerning disturbance to forest soil is much more complex. The dissimilarities in the results from various studies on this topic have shown the level of complexity. The lack of research investigating the consequences of the two extraction systems on the overall forest ecosystem is evident. Only a few studies were focused for example on the implications on biodiversity. However, the beneficial effects of best management practices, such as the application of snatch blocks during winching or positioning brush mats on the skid trails/ strip roads to reduce soil compaction, have been clearly demonstrated.
... In agreement with the results obtained by Blasi et al. (2013), no significant difference was found between managed and unmanaged sites. In fact, it seems that silvicultural management (such as coppicing) does not always have an impact on the QBS-ar index or on the presence of soil invertebrates, but it depends from the intensity and type of practices (Latterini et al., 2023;Setälä et al., 2000;Venanzi et al., 2022). This could be due to the fact that the litter of forest soils maintains a high level of organic material and a favorable microclimate throughout the year, allowing the edaphic mesofauna to have a very short recovery time after disturbances such as tree cutting (Bird et al., 2000). ...
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Soil fauna has a crucial importance for the functioning of ecosystems and their conservation. Soil biota has a role in soil formation and distribution of organic matter, and groups like microarthropods can be used as indicators to assess soil quality and are often employed in monitoring programs. In the present study, the QBS-ar index, an index based on the presence/absence of microarthropod groups, was used to assess the level of soil quality in nine different sampling sites in the “Parco Naturale delle Alpi Marittime” and in the “Parco Naturale del Marguareis” (Cuneo, Piedmont). Forest soils, with different degree of management, and open environments (e.g., grasslands and peatlands) were analyzed comparatively, to investigate whether microarthropod fauna might be influenced by management and habitat type. The results show QBS-ar values are significantly higher in woodland soils compared to grasslands and peatlands (p < 0.05). The latter shows no significant difference between each other, although grasslands show a large range of values (108–214). Forest management does not seem to influence QBS-ar values (183–239), showing stable microarthropod communities both in the managed and unmanaged areas. In addition to this, QBS-ar values do not differ significantly in the different forest coenoses, confirming that woodlands have similar index values (p = 0.7). This study confirms that QBS-ar values in natural areas can vary depending on the environment. It is therefore important to consider clustering habitat types before assessing quality classes for QBS-ar values. Finally, sustainable forest management in the study area does not seem to affect significantly soil microarthropod presence in woodland sites.
... Concerning extraction operations, cable yarding is the most-applied harvesting systems in the northern Alps, while in the rest of the country, ground-based extraction based on forestry-fitted farm tractors equipped with winches or forwarding boxes is still very common [39]. Skidders and forwarders have started to be widespread only in recent years [11,40,41]. In Turkey as well, felling and processing are mainly motor-manual using chainsaws, and extraction is based on skidding, generally via forestry-fitted farm tractor [42]. ...
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Precision forestry is a useful technique to help forest stakeholders with proper sustainable forest management. Modern sensors and technologies, with special reference to the sustainability of forest operations, can be applied on a variety of levels, including the monitoring of forest activities regarding the three pillars (economy, environment, and society). In this review, we summarised the current level of knowledge regarding the use of precision forestry techniques for monitoring forest operations. We concentrated on recent data from the last five years (2019-2023). We demonstrated how an Industry 4.0 strategy for remote and proximal monitoring of working performance can be effective when using CAN-bus and StanForD data collected by modern forest machines. The same information can be effectively used to create maps of soil trafficability and to evaluate the patterns of skid tracks or strip roads built as a result of forest intervention. Similar information can be gathered in the case of small-scale forestry by using GNSS-RF (Global Navigation Satellite Systems-Radio Frequency) or even monitoring systems based on smartwatches or smartphones. LiDAR and Structure for Motion (SfM) photogrammetry are both useful tools for tracking soil rutting and disturbances caused by the passage of forest machinery. SfM offers denser point clouds and a more approachable method, whereas laser scanning can be considerably faster but needs a more experienced operator and better data-processing skills. Finally, in terms of the social component of sustainability, the use of location sharing technologies is strongly advised, based for instance on GNSS-RF to monitor the security of forest workers as they operate.
... For these kinds of forests, the standard management applied is high forest and following the Continuous Cover Forestry (CCF) criteria, the shelterwood system is the most common treatment adopted for European beech forests, mostly in the Mediterranean area [2,[4][5][6]. In the framework of the shelterwood system, thinning interventions are crucial for the proper development of the stand [7]. ...
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In the Mediterranean area, the most common management of beech forests relies on the shelterwood system. However, more effort has been put into developing alternative silvicultural treatments to enhance the forests’ capacity to provide the higher ecosystem services. The crop-tree management system seems to perform well, particularly under the economic point of view. Moreover, it can provide higher quality timber from thinning interventions which are carried out before the end of the rotation period. However, very few articles have been found in the literature dealing with evaluation of the economic and environmental performance of the alternative thinning method based on crop-tree management (AT) in comparison to the traditional thinning from below typical of the shelterwood system (TT). Therefore, three study areas in Italy were selected to assess working productivity, costs and GHG emissions associated with the two methods. In the study areas with the application of mechanized extraction systems, AT showed higher work productivity and lower costs than TT, whereas GHG emissions reduction by AT was observed only in one of the three study areas. There was not significant improvement related to AT application when using animals for extraction operations. AT was more economically sustainable for thinning interventions in beech high forests, but the reduction of GHG emissions was not as effective as in TT. Crop-tree management proved to be a suitable option to be applied in beech forest stands, although further studies should focus on the overall rotation cycle and include the evaluation of impacts on productivity of a higher presence of saplings expected after crop-tree intervention.
Article
European beech (Fagus sylvatica L.) forests in Central and Southern Italy are managed applying the shelterwood system. Prior to the regeneration cut, it is common to apply 2-3 thinning interventions, aiming to obtain mostly firewood, considering the low dimension and poor quality of the stems. These interventions are usually carried out by local forest enterprises relying on a low or medium level of mechanization (small-scale forestry). In particular, the short wood system is applied, thus processing the logs to 1 m length and extracting them with forestry-fitted farm tractors equipped with forwarding bins. Despite the large application of this harvesting system in the Mediterranean forestry, no information is available in the literature about its possible disturbance to the forest soil. To fulfill this knowledge gap, we developed the first assessment of soil physicochemical (bulk density, penetration resistance, shear resistance , organic matter content) and biological (soil microarthropods biodiversity evaluated with the QBS-ar index, that is, an index based on the idea that high-quality soils have more groups of microarthropods that are morphologically better adapted to the soil than low-quality soils) properties for this kind of logging operation. In three case study areas in Central Italy, we applied an experimental design to evaluate separately the impacts related to the passage of the machine and that of the silvicultural treatment itself. We further applied linear mixed-effect models to investigate the relationship between changes in soil physicochemical and biological properties. We found the effect of the silvicultural treatment to be negligible, but there was a significant alteration of the investigated parameters in the soil affected by the passage of the machine. Soil penetration and shear resistance doubled in the forwarding trails (0.25 MPa and 4.02 t m À2 , respectively) in comparison with the other two experimental treatments (control area and soil not affected by the machine passage; about 0.12 MPa and 2.10 t m À2 , respectively). Soil organic matter and soil microarthropod biodiversity (QBS-ar index) were reduced by 25% in the forwarding trails (about 30% and 92 respectively) in comparison with the soil not affected by the machine passage (about 39% and about 130, respectively). Such significant disturbance, which occurred even if the applied machinery had lower weight in comparison to other
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Purpose of Review Ground-based mechanized forest operations can cause severe soil disturbances that are often long lasting and detrimental to the health of forested ecosystems. To reduce these soil disturbances, focus is being increasingly directed at identifying and using appropriate mitigation techniques. This systematic review considered 104 scientific articles and reported the main findings according to four core themes: terrain-related factors, operational planning, machine modifications, and types of amendments used to mitigate machine-induced soil impacts. Recent Findings For terrain-related factors, most severe disturbances occur on machine operating trails exceeding 20% slope and that soil bulk density and rut depth show greater increases in fine-textured soils. When considering operational planning, trafficability maps proved to be helpful in reducing the frequency and magnitude of soil damages as well as the length of trails needed within harvest sites, especially if they are regularly updated with weather information. Machine modifications, through high flotation tires, use of extra bogie axle, lower inflation pressure, and use of steel flexibles tracks, are highly researched topics because of the considerable upside in terms of machine ground pressure distribution and increased traction. Two main types of amendments emerged to mitigate soil disturbances: brush mats and mulch cover. Brush mats created from harvesting debris can spread the load of a machine to a greater area thereby lowering peak loads transferred to the soil. Brush mats of 15–20 kg m ⁻² are being recommended for adequate soil protection from harvesting operations. Summary To conclude, we outline recommendations and strategies on the use of soil mitigation techniques within cut-to-length forest operations. New research opportunities are also identified and discussed. Considering single factors causing machine-induced soil disturbances remains important but there is a pressing need for having a multi-disciplinary approach to tackle the complex problems associated with machine/soil/plant interactions.
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Purpose of Review Mechanized logging operations with ground-based equipment commonly represent European production forestry but are well-known to potentially cause soil impacts through various forms of soil disturbances, especially on wet soils with low bearing capacity. In times of changing climate, with shorter periods of frozen soils, heavy rain fall events in spring and autumn and frequent needs for salvage logging, forestry stakeholders face increasingly unfavourable conditions to conduct low-impact operations. Thus, more than ever, planning tools such as trafficability maps are required to ensure efficient forest operations at reduced environmental impact. This paper aims to describe the status quo of existence and implementation of such tools applied in forest operations across Europe. In addition, focus is given to the availability and accessibility of data relevant for such predictions. Recent Findings A commonly identified method to support the planning and execution of machine-based operations is given by the prediction of areas with low bearing capacity due to wet soil conditions. Both the topographic wetness index (TWI) and the depth-to-water algorithm (DTW) are used to identify wet areas and to produce trafficability maps, based on spatial information. Summary The required input data is commonly available among governmental institutions and in some countries already further processed to have topography-derived trafficability maps and respective enabling technologies at hand. Particularly the Nordic countries are ahead within this process and currently pave the way to further transfer static trafficability maps into dynamic ones, including additional site-specific information received from detailed forest inventories. Yet, it is hoped that a broader adoption of these information by forest managers throughout Europe will take place to enhance sustainable forest operations.
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This research was conducted to determine the cause, intensity and location of damage (stem, butt end, root collar, root) and the extent of damage to standing trees during felling and processing by an harvester and timber extraction by a forwarder (cut-to-length system). The research was conducted in the central part of the Republic of Croatia in the Management Unit (MU) “Bjelovarska Bilogora” during the thinning of Subcompartment 14b, area of 18.28 ha, in the stand of hornbeam (Carpino betuli—Quercetum roboris fagetosum Rauš 1975), age 70, and of Subcompartment 14c, area of 9.07 ha, in a stand of common beech (Carici pilosae—Fagetum Oberdorfer 1957) aged 79 years. The thinning intensity was 12.13% in Subcompartment 14b and 13.72% in Subcompartment 14c. Field measurements were carried out on sample plots—the first time in 2017 to determine the intensity and characteristics of the damage to standing trees with regard to the cause of the damage (harvester or forwarder), and the second time in 2018 to determine the overall intensity and features of the damage to standing trees after finishing harvesting operations. For all trees remaining in the stand after the harvesting operations, the following were determined: tree species, diameter at breast height (DBH), the position of the tree in the stand depending on the forest traffic infrastructure, and—if damaged—cause of damage, type of damage, the position of damage on the tree, and dimensions of damage. The intensity of the damage was expressed by the ratio of damaged and undamaged trees, with a detailed analysis of bark damage (squeezed-bark damage and peeled-bark injuries). The results of the research indicate the highest prevalence of peeled-bark injuries. In relation to the total number of standing trees, trees with peeled-bark injuries were more represented in Subcompartment 14c (39%) than in Subcompartment 14b (33%). In Subcompartment 14b, the harvester and the forwarder damaged an equal number of trees, while in Subcompartment 14c, the harvester damaged 59% of the damaged trees. In both subcompartments, an average of 83% of (peeled bark) injuries were up to 1.3 m above the ground. In both subcompartments, the most common (67%) were injuries up to 100 cm2 in size, for which many authors claim the tree can heal by itself. Given the increasing use of harvester-forwarder systems in deciduous stands and research results that indicate possible damage to standing trees, it is necessary to pay attention to all phases of planning and execution of timber harvesting operations, thus minimising negative effects.
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Soil compaction associated with mechanized wood harvesting can long-lastingly disturb forest soils, ecosystem function, and productivity. Sustainable forest management requires precise and deep knowledge of logging operation impacts on forest soils, which can be attained by meta-analysis studies covering representative forest datasets. We performed a meta-analysis on the impact of logging-associated compaction on forest soils microbial biomass carbon (MBC), bulk density, total porosity, and saturated hydraulic conductivity (K sat) affected by two management factors (machine weight and passage frequency), two soil factors (texture and depth), and the time passed since the compaction event. Compaction significantly decreased soil MBC by −29.5% only in subsoils (>30 cm). Overall, compaction increased soil bulk density by 8.9% and reduced total porosity and K sat by −10.1 and −40.2%, respectively. The most striking finding of this meta-analysis is that the greatest disturbance to soil bulk density, total porosity, and K sat occurs after very frequent (>20) machine passages. This contradicts the existing claims that most damage to forest soils happens after a few machine passages. Furthermore, the analyzed physical variables did not recover to the normal level within a period of 3-6 years. Thus, altering these physical properties can disturb forest ecosystem function and productivity, because they play important roles in water and air supply as well as in biogeochemical cycling in forest ecosystems. To minimize the impact, we recommend the selection of suitable logging machines and decreasing the frequency of machine passages as well as logging out of rainy seasons especially in clayey soils. It is also very important to minimize total skid trail coverage for sustainable forest management.
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Purpose of Review This paper aims to retrace the most significant management strategies adopted across European beech forests over the last 25 years, highlighting those that are most efficient and promising. We investigate five main topics including forest management, forest models, species mixture, genetic, and regeneration. Recent Findings European beech is one of the most widespread and important tree species for the European forest sector. In the light of the ongoing climate crisis, understanding the growth dynamics and the response of beech forests to climate change is crucial to identify advantageous management strategies. Ecology, growth, management, distribution, interaction with other species, genetic, and regeneration aspects of European beech were investigated in different geographical areas of Europe. Despite recent researches focusing on climate change issues, how adaptation and mitigation measures can be integrated into silvicultural guidelines to improve the resilience of European beech forests remains unclear. Summary To answer this question, we collected and reviewed articles about the management of European beech facing climate change, which were published in peer-reviewed journals over the last 25 years. Articles were grouped into five geographic European areas, according to the classification used by the State of Europe’s forests. Obtained articles were further clustered into five main topics: management, mixed forest, modelling, genetic, and regeneration. The review highlighted the importance of using long-term monitoring plots to understand the effect of climate change on the stability of European beech forests, suggesting climate-smart measures that would help these forests adapt to climate change.
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Purposeof Review Paired catchment studies have documented the extent to which forest harvesting impairs forested watersheds. Adverse effects on stream water quality and aquatic ecosystems following ground-based harvesting operations that open forest canopies and compact soils have spurred the implementation of best management practices (BMPs) that are intended to limit runoff volumes (i.e., water yield increase, WYI) and total sediment yields (TSY) into streams. The purpose of this review is to highlight recent insights from water and sediment yield studies, ranging in scale from hillslope plots to catchments, that reveal the sources and mechanisms of hydrological impairment and recovery, and point to specific strategies for developing more targeted BMPs that help prevent, mitigate, and rehabilitate forested watersheds. Recent Findings In the context of forested watersheds, contemporary BMPs have successfully lowered runoff (WYI) and total sediment yields (TSY) relative to previously reported values. Recent research strongly indicates that the delivery of WYIs and TSYs to streams following forest harvesting is still high. Because many factors such as the intensity and extent of management activities and headwater catchment activities interact, improving the effectiveness of generic, inflexible BMPs will be challenging. Recent findings indicate that a site-specific, highly tailored application of a combination of BMP measures before, during, and after the harvesting operation is needed if a further reduction of runoff and sediment delivery to streams is to be achieved. Summary Analyses of 155 paired catchment studies and 39 hillslope plots revealed that forest harvesting resulted in average increases of WYI by 180 mm (+ 46%) and TSY by 477 t km⁻² year⁻¹ (+ 700%). Smaller hillslope plots established on forest roads, skid trails, and harvested areas underestimate these values (WYI of 8.2 mm, TSY was 42.2 t km⁻² year⁻¹). In extreme circumstances such as clearcutting, enhanced WYI and TSY may persist up to several decades before returning to pre-harvest levels. WY increased with increasing precipitation and with, and proportional to, the catchment area harvested, regardless of climatic zone or tree species composition; TSY increased with increasing rainfall and catchment area. Both the impact of harvesting and the time required for natural recovery of hydrologic responses depended on the response but can be shortened when applying contemporary forestry BMPs.
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Forest operations have become increasingly reliant on mechanized harvesting equipment due to their increased production capacities in competitive markets. However, operating heavy machinery in mountainous terrain poses numerous operational and accessibility challenges from steep slopes, erosion risk, and poor road access. Geographic Information Systems (GIS) have effectively been used in various studies to identify areas in mountainous landscapes that pose no or reduced constraints for harvesting equipment operation. This study introduces the Harvest Operability Index (HOI), which rates a landscape for wheel-based equipment suitability (i.e., operability) and assesses its application in 13,118 ha of the Jocassee Gorges Natural Resource Area, situated on the Southern Blue Ridge Escarpment in Northwestern South Carolina, USA. The HOI incorporated slope, distance from roads, cost distance from major highways, primary Streamside Management Zones (SMZ), stand age, and soil suitability ratings for harvesting equipment operation. Upon reclassification to a 5-tier suitability scale, the HOI revealed 60% (7824 ha) of the case study area was in a Slope Exclusion Zone, or land area inoperable for wheel-based equipment due to steep slopes. Values of Very Poor and Poor Operability occupied less than 1% (213 ha) of land area whereas Moderate Operability values were 9% of the land area (1257 ha). Values of Good Operability occupied 18% (2442 ha) of the study area and values of Very Good Operability occupied 10% (1381 ha). These results reflected the challenges of mechanized harvesting in the study area due to a preponderance of steep slopes and poorly suited soil. Our model delineated areas of high equipment operability in two locations in the study area, despite a lack of recent logging activity around them. Results of the HOI analysis offer an accessible way for forest managers to better prioritize logging operations in areas that are highly operable and therefore more likely to possess lower overall harvesting costs, for wheel-based harvesting systems. The HOI can also be used as an asset for other forest management priorities, such as identifying highly operable areas that can use timber harvesting for fuel reduction and ecological restoration in fire-dependent forests. This model can be applied to various other regions where mountainous terrain poses a limitation to wheel-based harvesting equipment operation- and where wheel-based equipment is essential to advance the pace and scale of harvesting for ecological restoration.
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Natural treefall gaps have a substantial role in maintaining soil and plant diversity in old-growth forests. However, the amount of information on the effects of gaps on the recovery of physical and chemical properties of compacted soils is scarce. We tested the hypothesis that natural treefall gaps accelerate the restoration of compacted soil by enhancing biological and microbial activity in the topsoil after a period of five years. Five years after a ground-based skidding operation in the Hyrcanian forest, the recovery levels of soil properties were compared among different treatments including natural canopy gaps with an area of 200 m2 (NCG), clear-cuts with an area of 1600 m2 (CC), disturbed trails under a dense canopy (DDC), and an undisturbed area (UND) as control. The lowest soil bulk density (1.07 g cm-3), penetration resistance (1.11 MPa), and the highest macroporosity (36.3%), and sand content (14.4%) among treatments were recorded for the NCG followed by DDC and CC treatments. Significantly lower values of soil pH, and electric conductivity and the highest values of soil organic C, total N, available P, K, Ca, and Mg were detected under the NCG followed by the DDC and CC treatments, as compared to the UND area. The highest values of earthworm density and dry mass, and soil microbial respiration were found in the NCG followed by the DDC and CC treatments. Fine root biomass was significantly higher in the UND area (92.27 g m-2) followed by the DDC, NCG and CC treatments. We can conclude that the effects of gap size on the recovery values of compacted soil were significant in terms of greater nutrient availability and higher earthworm density and dry mass, suggesting that mimicking natural canopy gap was more effective than the clear-cut gap (CC) for the resilience of the forest stand in the restoration of soil quality.
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Background Forests provide the largest terrestrial sink of carbon (C). However, these C stocks are threatened by forest land conversion. Land use change has global impacts and is a critical component when studying C fluxes, but it is not always fully considered in C accounting despite being a major contributor to emissions. An urgent need exists among decision-makers to identify the likelihood of forest conversion to other land uses and factors affecting C loss. To help address this issue, we conducted our research in California, Colorado, Georgia, New York, Texas, and Wisconsin. The objectives were to (1) model the probability of forest conversion and C stocks dynamics using USDA Forest Service Forest Inventory and Analysis (FIA) data and (2) create wall-to-wall maps showing estimates of the risk of areas to convert from forest to non-forest. We used two modeling approaches: a machine learning algorithm (random forest) and generalized mixed-effects models. Explanatory variables for the models included ecological attributes, topography, census data, forest disturbances, and forest conditions. Model predictions and Landsat spectral information were used to produce wall-to-wall probability maps of forest change using Google Earth Engine. Results During the study period (2000–2017), 3.4% of the analyzed FIA plots transitioned from forest to mixed or non-forested conditions. Results indicate that the change in land use from forests is more likely with increasing human population and housing growth rates. Furthermore, non-public forests showed a higher probability of forest change compared to public forests. Areas closer to cities and coastal areas showed a higher risk of transition to non-forests. Out of the six states analyzed, Colorado had the highest risk of conversion and the largest amount of aboveground C lost. Natural forest disturbances were not a major predictor of land use change. Conclusions Land use change is accelerating globally, causing a large increase in C emissions. Our results will help policy-makers prioritize forest management activities and land use planning by providing a quantitative framework that can enhance forest health and productivity. This work will also inform climate change mitigation strategies by understanding the role that land use change plays in C emissions.
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Numerous studies have concluded that forestry Best Management Practices (BMPs) are effective at mitigating erosion and sedimentation caused by forest operations; however, the complex relationship between forestry BMPs and erosion is largely unexamined. In this study, BMP implementation rates, which are percentages ranging from 0 to 100% that indicates how well an operator instituted recommended practices in the field, and predicted erosion rates, obtained by using USLE-Forest, were calculated for 108 recent harvests in twelve states and three physiographic regions in the southeastern U.S. BMP implementation rates were subdivided into three levels of application: BMP+ (>90% implementation), BMP-standard (80–90% implementation), and BMP− (<80% implementation). Skid trails (86.5 Mg ha⁻¹ yr⁻¹) and haul roads (90.3 Mg ha⁻¹ yr⁻¹) eroded at relatively high rates at the BMP− level across the southeast. This emphasizes the importance of adequate BMP measures such as utilizing water diversion structures and cover management at these features to better protect water quality. The overall weighted average erosion estimates for all regions at the BMP-standard (10.4 Mg ha⁻¹ yr⁻¹) and BMP+ (6.6 Mg ha⁻¹ yr⁻¹) levels were <11 Mg ha⁻¹ yr⁻¹, indicating that water quality and site productivity are largely protected when adequate BMPs are implemented, and Streamside Management Zones (SMZs) are utilized along streams. Approximately 94% of the sites sampled were classified as either BMP-standard or BMP+, demonstrating that BMPs are being implemented consistently throughout the southeast. Spearman ρ correlation analyses were performed for all variables. Forestry BMP implementation and erosion estimates had significant negative correlations, especially for skid trails (Spearman ρ = −0.59, p-value < 0.0001) and haul roads (Spearman ρ = −0.39, p-value = < 0.0001), as well as for all regions across the southeast. These variables, however, were poorly correlated for stream crossings, indicating that current audit questions in the southeast may not fully address erosion. Additionally, BMP implementation and erosion estimates exhibited a significant negative correlation (R² = 0.28, p-value < 0.0001) based on a quadratic regression line for all features, reinforcing that as BMP implementation increases, predicted erosion generally decreases.