56 research outputs found
The effect of natural disturbances on forest biodiversity: an ecological synthesis
Disturbances alter biodiversity via their specific characteristics, including severity and extent in the landscape, which act
at different temporal and spatial scales. Biodiversity response to disturbance also depends on the community characteristics
and habitat requirements of species. Untangling the mechanistic interplay of these factors has guided disturbance
ecology for decades, generating mixed scientific evidence of biodiversity responses to disturbance. Understanding the
impact of natural disturbances on biodiversity is increasingly important due to human-induced changes in natural disturbance
regimes. In many areas, major natural forest disturbances, such as wildfires, windstorms, and insect outbreaks, are
becoming more frequent, intense, severe, and widespread due to climate change and land-use change. Conversely, the
suppression of natural disturbances threatens disturbance-dependent biota. Using a meta-analytic approach, we analysed
a global data set (with most sampling concentrated in temperate and boreal secondary forests) of species assemblages
of 26 taxonomic groups, including plants, animals, and fungi collected from forests affected by wildfires,
windstorms, and insect outbreaks. The overall effect of natural disturbances on α-diversity did not differ significantly
from zero, but some taxonomic groups responded positively to disturbance, while others tended to respond negatively. Disturbance was beneficial for taxonomic groups preferring conditions associated with open canopies
(e.g. hymenopterans and hoverflies), whereas ground-dwelling groups and/or groups typically associated with shady conditions
(e.g. epigeic lichens and mycorrhizal fungi) were more likely to be negatively impacted by disturbance. Across all
taxonomic groups, the highest α-diversity in disturbed forest patches occurred under moderate disturbance severity,
i.e. with approximately 55% of trees killed by disturbance. We further extended our meta-analysis by applying a unified
diversity concept based on Hill numbers to estimate α-diversity changes in different taxonomic groups across a gradient
of disturbance severity measured at the stand scale and incorporating other disturbance features. We found that
disturbance severity negatively affected diversity for Hill number q = 0 but not for q = 1 and q = 2, indicating that
diversity–disturbance relationships are shaped by species relative abundances. Our synthesis of α-diversity was extended
by a synthesis of disturbance-induced change in species assemblages, and revealed that disturbance changes the β-diversity
of multiple taxonomic groups, including some groups that were not affected at the α-diversity level (birds and woody
plants). Finally, we used mixed rarefaction/extrapolation to estimate biodiversity change as a function of the proportion
of forests that were disturbed, i.e. the disturbance extent measured at the landscape scale. The comparison of intact and
naturally disturbed forests revealed that both types of forests provide habitat for unique species assemblages, whereas species
diversity in the mixture of disturbed and undisturbed forests peaked at intermediate values of disturbance extent in the
simulated landscape. Hence, the relationship between α-diversity and disturbance severity in disturbed forest stands was
strikingly similar to the relationship between species richness and disturbance extent in a landscape consisting of both disturbed
and undisturbed forest habitats. This result suggests that both moderate disturbance severity and moderate disturbance
extent support the highest levels of biodiversity in contemporary forest landscapes.British Ecological Society LRB20/1002Junta de AndaluciaEuropean Commission B-FQM-366-UGR20Centro ANID Basal FB210015Direccion de Investigacion Universidad de La Frontera DIUFRO DI20-0066Federal Ministry of Education & Research (BMBF)Max Planck SocietyINCT Madeiras da AmazoniaFederal Ministry of Education & Research (BMBF) 01LB1001A
01LK1602ABrazilian Ministry of Science, Technology and Innovation (MCTI/FINEP) 01.11.01248.00Max Planck SocietyRussian Science Foundation (RSF) 21-14-00227Ministry of Education, Youth & Sports - Czech Republic
Czech Republic Government LTC 20058Czech Academy of Sciences RVO67985939UK Research & Innovation (UKRI)Natural Environment Research Council (NERC) GR3/11743Greek project POL-AEGIS, Program THALES MIS 376737Projekt DEAL
TH 2218/5-
Effect of Herbaceous Layer Interference on the Post-Fire Regeneration of a Serotinous Pine (Pinus pinaster Aiton) across Two Seedling Ages
Herbaceous vegetation is a major source of interference with the regeneration of woody
species. This is particularly the case after forest fires, as a dense herbaceous layer usually regenerates
naturally. Although the competitive effect of the herbaceous vegetation upon tree seedlings has
been widely studied, there are still gaps in knowledge for management related to the effect of
tree seedling age and size on the outcome of the interaction. In this study, we seek to determine
the response of maritime pine (Pinus pinaster Aiton) seedlings to herbaceous competition at two
different seedling ages. For that, two treatments of herbaceous competition were implemented,
namely unweeded (no action around pine seedlings) and weeded (herbaceous cover removed around
pine seedlings). Treatments were conducted twice (2 and 4 years after the fire), and we monitored
seedling survival and growth at the end of each growing season. The treatments were implemented
across three adjacent landscape units that differed in the management of burned wood and that are
representative of common post-fire scenarios: no intervention, salvage logging, and an intermediate
degree of intervention. Weeding increased seedling survival from 44.7% to 67.8% when seedlings
were 2 years old, but had no effect for four-year-old seedlings, which showed 99% survival. Seedling
growth also increased in the weeding treatment, but only slightly. Moreover, growth (and survival
for two-year-old seedlings) was strongly correlated with initial seedling size, particularly in the
case of two-year-old seedlings. Initial pine seedling height was strongly and positively correlated
with the height of the herbaceous layer, supporting the existence of microsite features that promote
plant growth above competitive effects. The results support that management actions conducive to
foster post-fire pine forest restoration in this Mediterranean ecosystem should reduce herbaceous
competition at early stages after fire (second or third year) and focus on larger seedlings.This research was funded by projects 10/2005 from the Organismo Autónomo de Parques Nacionales
(Spanish Government), CGL2008-01671 from the Spanish Ministerio de Ciencia e Innovación (Spanish
Government), and P12-RNM-2705 from Junta de Andalucía (Andalusian regional Government)
Disturbance ecology in human societies
1. We define societal disturbances as discrete events that abruptly disrupt the functioning
of human societies. There is a variety of such events, including hurricanes,
floods, epidemics, nuclear accidents, earthquakes and wars, among others. These
disturbances can interact, further increasing their impacts. The severity of disturbances
does not only depend on their intrinsic properties (type, intensity and
magnitude) but also greatly on human aspects (socioeconomic, historical, political
and cultural aspects that define vulnerability).
2. Very large or severe disturbances are infrequent and unpredictable. Yet societal
disturbances are intrinsic to human societies; they have occurred through the
entire human history and will continue to occur in the future. We can increase
preparedness and recovery capacity but cannot avoid disturbances. The type,
regime and scale of disturbances change with the development of societies. The
increase in population density and complexity also increases the severity of many
disturbances.
3. Societal disturbances can temporarily disrupt the functioning of societies.
However, when those disturbances are frequent, societies adapt to them and
thus disturbances contribute to shape cultural evolution. That is, societal disturbances
have a cost at short temporal scales, but they can build up resilience at
mid-to
long-term
scales.
4. Understanding this dynamic view of human systems is becoming more important
as climate is changing, humans are overexploiting natural resources and humanity
is dense and hyperconnected. We need to take advantage of frequent small
disturbances, as they can build resilience and reduce the likelihood of infrequent
large and severe disturbances. Our challenge is to encourage actions and policies
to be prepared for unknown, unpredictable and unprecedented (infrequent)
large-scale
societal disturbances that will surely arrive
Revegetation through seeding or planting: A worldwide systematic map
Roughly 2 billion ha of land are degraded and in need of ecological restoration worldwide. Active restoration
frequently involves revegetation, which leads to the dilemma of whether to conduct direct seeding or to plant
nursery-grown seedlings. The choice of revegetation method can regulate plant survival and performance, with
economic implications that ultimately feed back to our capacity to conduct restoration. We followed a peerreviewed
protocol to develop a systematic map that collates, describes and catalogues the available studies on
how seeding compares to planting in achieving restoration targets. We compiled a database with the characteristics
of all retrieved studies, which can be searched to identify studies of particular locations and habitats,
objectives of restoration, plant material, technical aspects, and outcomes measured. The search was made in
eight languages and retrieved 3355 publications, of which 178 were retained. The systematic map identifies
research gaps, such as a lack of studies in the global South, in tropical rainforests, and covering a long time
period, which represent opportunities to expand field-based research. Additionally, many studies overlooked
reporting on important technical aspects such as seed provenance and nursery cultivation methods, and others
such as watering or seedling protection were more frequently applied for planting than for seeding, which limits
our capacity to learn from past research. Most studies measured outcomes related to the target plants but avoided
measuring general restoration outcomes or economic aspects. This represents a relevant gap in research, as the
choice of revegetation method is greatly based on economic aspects and the achievement of restoration goals
goes beyond the establishment of plants. Finally, we identified a substantial volume of studies conducted in
temperate regions and over short periods (0–5 y). This research cluster calls for a future in-depth synthesis,
potentially through meta-analysis, to reveal the overall balance between seeding and planting and assess whether
the response to this question is mediated by species traits, environmental characteristics, or technical aspects.
Besides identifying research clusters and gaps, the systematic map database allows managers to find the most
relevant scientific literature on the appropriateness of seeding vs. planting for particular conditions, such as
certain species or habitats.Spanish Ministerio de Ciencia, Innovacion y Universidades/FEDER RTI 2018-096187-J-100
RYC 2020-029407-IMinistry of Science and Innovation, Spain (MICINN) TED2021.130976 B.I00Consejeria de Economia, Conocimiento, Empresas y Universidad de la Junta de Andalucia/FEDER P18-RT-1927Universidad de Granada / CBU
Massive and effective acorn dispersal into agroforestry systems by an overlooked vector, the Eurasian magpie (Pica pica)
Oak regeneration and the expansion of forested sites in Eurasia rely on acorn dispersal by animals,
especially the Eurasian jay (Garrulus glandarius). However, in open agroforestry systems where jays
are absent, such as old fields far from acorn sources, oak recruitment still occurs. We hypothesize that the
Eurasian magpie (Pica pica), an abundant corvid in this system, substitutes the jay in its seed dispersal function.
By ringing 169 magpies, video recording >7500 acorn removal events with trail cameras, and radiotagging
337 acorns, we quantified that (1) magpies cached 41–56% of the annual acorn production of Quercus
ilex trees in single caches on the ground; (2) breeding pairs, and especially males, were the main acorn
dispersers; (3) each breeding magpie cached 169–1372 acorns in 6 weeks; and (4) the effectiveness of dispersal
(percentage of cached acorns resulting in seedlings) was 0.6–2.4%, which (5) yielded a high density
of emerged seedlings (56–439 seedlings/ha). We evidence that magpie could be a key species in the regeneration
of oak agroforestry mosaics because they massively and effectively dispersed acorns. However, in
our particular study site, effectiveness was low probably due to herbivory and summer drought stress (i.e.,
a context limitation rather than an intrinsic limitation of the disperser). As the distributions of magpies and
oaks overlap widely in Eurasia, effective acorn dispersal by magpies could have a significant role in largescale
oak forest recovery in strongly fragmented landscapes.This study was funded by the Spanish Ministerio de
Ciencia y Tecnología (CGL2014-53308-P), the REMEDINAL
network of the Madrid Autonomous Government
(S2013/MAE-2719 and S2018/EMT-4338), and the
University of Alcalá (CCG2014/BIO-02, UAH-GP2019-
6). LMB was supported by an FPI fellowship from the
Ministerio de Ciencia y Tecnología (BES-2015-075276).
ABL acknowledges Juan de la Cierva postdoctoral fellowship
and project RTI2018-096187-J-100 from Ministerio
de Ciencia, Innovación y Universidades
Linking animal behaviour and tree recruitment: Caching decisions by a scatter-hoarder corvid determine seed fate in a Mediterranean agroforestry system
1. Seed dispersal by scatter-hoarder
corvids is key for the establishment of important
tree species from the Holarctic region such as the walnut (Juglans
regia). However, the factors that drive animal decisions to cache seeds in specific
locations and the consequences of these decisions on seed fate are poorly
understood.
2. We experimentally created four distinct, replicated habitat types in a
Mediterranean agricultural landscape where the Eurasian magpie (Pica pica) is
a common scatter hoarder: soft bare soil; compacted bare soil; compacted soil
with a dense herbaceous cover; and soft linear bare soil made up of the irrigation
furrows that separated the rest of the treatments. We also experimentally
placed visual landmarks (stones, sticks and bunches of dry plants) to test if magpies
use them to place seed caches. Walnut dispersal from feeders to the habitats
was monitored by radiotracking and camera traps.
3. A sowing experiment simulating natural caches tested the effect of caching type
on seed germination and seedling emergence. Seed mass was controlled for the
dispersal and sowing experiments.
4. Magpies selected the two habitats with soft soil, and avoided the one with compacted
soil, to cache nuts. Seed mass did not affect dispersal distance, germination
or emergence; however, heavier seeds were cached more often under litter
and in the habitat with herbaceous cover, whereas lighter seeds were more often
buried in the soft bare soil habitat. Seed burial under soil or litter determined seed fate, as there was virtually no emergence from unburied nuts. There was
no evidence of any effect of the visual landmarks.
5. Synthesis. The consequences of seed caching for seedling early establishment
are driven by a fine decision-making
process of the disperser. Magpies seemed
to ponder the characteristics of the habitat and the seed itself to determine
where and how to cache each nut. By doing so, magpies reinforced the quality of
seed dispersal effectiveness, as they cached walnuts in locations that enhanced
both seed survival and seedling emergence.Ministry of Science and Innovation, Spain (MICINN)Instituto de Salud Carlos III
Spanish Government IJC2018-036411-
Spanish Government PID2019-106806GB-I00RTI2018-096187-J-I00REMEDINAL S2018/EMT-4338SS2018/EMT-4338Spanish Government CGL2014-53308-PUniversidad de Alcala CCG2014/BIO-02
UAH-GP2019-
Deadwood Decay in a Burnt Mediterranean Pine Reforestation
Dead wood remaining after wildfires represents a biological legacy for forest regeneration, and its decay is both cause and consequence of a large set of ecological processes. However, the rate of wood decomposition after fires is still poorly understood, particularly for Mediterranean-type ecosystems. In this study, we analyzed deadwood decomposition following a wildfire in a Mediterranean pine plantation in the Sierra Nevada Natural and National Park (southeast Spain). Three plots were established over an elevational/species gradient spanning from 1477 to 2053 m above sea level, in which burnt logs of three species of pines were experimentally laid out and wood densities were estimated five times over ten years. The logs lost an overall 23% of their density, although this value ranged from an average 11% at the highest-elevation plot (dominated by Pinus sylvestris) to 32% at an intermediate elevation (with P. nigra). Contrary to studies in other climates, large-diameter logs decomposed faster than small-diameter logs. Our results provide one of the longest time series for wood decomposition in Mediterranean ecosystems and suggest that this process provides spatial variability in the post-fire ecosystem at the scale of stands due to variable speeds of decay. Common management practices such as salvage logging diminish burnt wood and influence the rich ecological processes related to its decay.This study was supported by Project 10/2005 from the Organismo Autónomo de Parques Nacionales (Spanish Government), CGL2008-01671 from the Spanish Ministerio de Ciencia e Innovación, and P12-RNM-2705 from Junta de Andalucía. A.B.L. acknowledges funding from Juan de la Cierva grant by Ministerio de Economía y Competitividad (FJCI-2015-23687). C.R.M-G. had a Ph.D. grant from the National University of Asunción (Paraguay) and Carolina Foundation (Spain)
Does post-disturbance salvage logging affect the provision of ecosystem services?
Background: Forest fires, insect outbreaks, and windstorms are common forest disturbances that are expected to increase in importance in coming decades. Post-disturbance management often involves salvage logging, i.e. the felling and removal of the affected trees. However, harvesting these biological legacies may represent a second disturbance whose effects on ecosystem processes add on those of the initial disturbance. Many of the potentially affected processes, such as soil erosion and stream water quality, represent regulating and supporting ecosystem services important for human society. In the last 15years, much empirical evidence has been gathered on the ecological consequences of this management practice, and it has now become necessary to synthesise this evidence in meaningful ways for managers and decision-makers.
Methods: With this systematic review we aim to synthesise the literature on the effects of salvage logging on ecosystem services and determine the effects of major effect modifiers such as disturbance type and intensity, the timing and method of logging, and the type of forest. We will conduct searches of the primary scientific literature, which will be selected and categorised according to its relevance to the topic and its quality. Each relevant article will be read in full to obtain the necessary data for meta-analysis and to identify its main conclusions. Mixed-effects models will be performed to assess the effects of the identified effect modifiers on the effect sizes of the salvage intervention on ecosystem services and to account for random effects arising from studies being performed in the same area. Sensitivity analyses will test the potential effects of study quality, and publication bias will be assessed with the trim and fill method. We will present the results as a narrative review and a meta-analysis
Increasing disturbance demands new policies to conserve intact forest
Ongoing controversy over logging the ancient Białowieża Forest in Poland symbolizes a global problem for policies and management of the increasing proportion of the earth's intact forest that is subject to postdisturbance logging. We review the extent of, and motivations for, postdisturbance logging in protected and unprotected forests globally. An unprecedented level of logging in protected areas and other places where green‐tree harvest would not normally occur is driven by economic interests and a desire for pest control. To avoid failure of global initiatives dedicated to reducing the loss of species, five key policy reforms are necessary: (1) salvage logging must be banned from protected areas; (2) forest planning should address altered disturbance regimes for all intact forests to ensure that significant areas remain undisturbed by logging; (3) new kinds of integrated analyses are needed to assess the potential economic benefits of salvage logging against its ecological, economic, and social costs; (4) global and regional maps of natural disturbance regimes should be created to guide better spatiotemporal planning of protected areas and undisturbed forests outside reserves; and (5) improved education and communication programs are needed to correct widely held misconceptions about natural disturbances.We thank the Bavarian Forest National Park administration for funding the travel costs of RN and DL in support
of this manuscript. ABL acknowledges support from grants
P12-RNM-2705 and FJCI- 2015–23687
Effects of Post-Fire Deadwood Management on Soil Macroarthropod Communities
Dead wood comprises a vast amount of biological legacies that set the scene for ecological
regeneration after wildfires, yet its removal is the most frequent management strategy worldwide.
Soil-dwelling organisms are conspicuous, and they provide essential ecosystem functions, but their
possible affection by different post-fire management strategies has so far been neglected. We analyzed
the abundance, richness, and composition of belowground macroarthropod communities under two
contrasting dead-wood management regimes after a large wildfire in the Sierra Nevada Natural and
National Park (Southeast Spain). Two plots at different elevation were established, each containing
three replicates of two experimental treatments: partial cut, where trees were cut and their branches
lopped off and left over the ground, and salvage logging, where all the trees were cut, logs were
piled, branches were mechanically masticated, and slash was spread on the ground. Ten years
after the application of the treatments, soil cores were extracted from two types of microhabitat
created by these treatments: bare-soil (in both treatments) and under-logs (in the partial cut treatment
only). Soil macroarthropod assemblages were dominated by Hemiptera and Hymenoptera (mostly
ants) and were more abundant and richer in the lowest plot. The differences between dead-wood
treatments were most evident at the scale of management interventions: abundance and richness
were lowest after salvage logging, even under similar microhabitats (bare-soil). However, there were
no significant differences between microhabitat types on abundance and richness within the partial
cut treatment. Higher abundance and richness in the partial cut treatment likely resulted from higher
resource availability and higher plant diversity after natural regeneration.This study was supported by Project 10/2005 from the Organismo Autónomo de Parques Nacionales
(Spanish Government), CGL2008–01671 from the Spanish Ministerio de Ciencia e Innovación, and P12-RNM-2705
from Junta de Andalucía. Programa Nacional de incentivo a investigadores (PRONII) and Programa de vinculación
de científicos y tecnólogos from Comisión Nacional de Ciencia y Tecnología (Paraguay). A.B.L. acknowledges a
postdoctoral grant from the Alexander von Humboldt Foundation. C.R.M-G. had a Ph.D. grant from the National
University of Asunción (Paraguay) and Carolina Foundation (Spain)
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