We carried out a posthurricane evaluation of Broughtonia cubensis (Lindl.) Cogn., an endemic Cuban epiphytic orchid, after Hurricane Ivan (2004). We studied the transient responses in the stochastic ...dynamics of the species at three different sites over 13 successive years (2006–2019), monitored plot inventories (464 individuals in 10 transects) and built stochastic population models. The deterministic stochastic growth rate values (λ) did not significantly differ (F = 2.76; p > 0.076) among the three sites over the 2006–2019 period. The long‐term stochastic growth rate was λs= 0.973 0.932, 1.034. The matrix elements that had the largest effect on λ were the transition to and stasis within the largest size class. Transient responses explained an average of 86% of the variation in the observed population growth rates R2forrTDvs.robs, compared to 4% of the variation in the vital rates R2forrVRvs.robs. Because transient dynamics are dependent on the population size composition, we ran extinction risk analyses under two scenarios: a population composed mainly of juveniles and another composed mainly of adults. There was little risk of falling below the quasi‐extinction threshold before 25 year for both juveniles and adults. However, the risk of quasi‐extinction was almost certain for both size classes by 80 year. We also simulated the effect of increasing the hurricane occurrence probability over 80 year on the population. There was little risk of extinction before 20 year in the baseline model, but there was a significant risk of extinction within 5 year when 90% of the individuals were affected by a new hurricane event.
We carried out a posthurricane evaluation of Broughtonia cubensis (Lindl.) Cogn., an endemic Cuban epiphytic orchid, after Hurricane Ivan (2004). Using stochastic population models, we studied the transient responses in the stochastic dynamics at three different sites over 13 years (2006–2019).
In the valuable orchid genus Cypripedium, the section Irapeana consists of a distinctive group of Mesoamerican species that is formed by Cypripedium dickinsonianum Hágsater, C. irapeanum Lex., and C. ...molle Lindl. All lady slipper orchids exhibit different distributions and abundances. Data analysis that used herbarium accessions and field investigations indicated that the habitats of these three species have been dramatically reduced. Prospecting for suitable habitats based on climatic, vegetation, and soil parameters allows us to predict potential distributions. Conservation strategies, such as ex situ propagation by asymbiotic and symbiotic approaches, have indicated that the culture media used are a determining factor for seedling development. Mycorrhizal isolates play a main role in the compatibility and further development of germinated seeds. The fungi isolated from adult plants belong to two different families, which makes it possible that widely distributed C. irapeanum populations will be fungal-specific as well as restricted for C. molle. Root mycorrhization patterns occur high on the secondary roots. In contrast with other species of the genus, in situ germination can occur over a short period of two months, but we have documented periods as long as ten years. Cypripedium is a highly problematic genus for ex situ conservation because the germination requirements and cultures are poorly documented, and there is great urgency for in situ conservation to develop strategies for identifying hotspot habitats and actualize the protection status to avoid extinction of this genus.
Plant establishment, presence of arbuscular mycorrhizal fungi (AMF) and other rhizospheric fungi were studied in mine wastes from Zimapan, Hidalgo state, Mexico, using a holistic approach. Two ...long-term afforested and three non-afforested mine tailings were included in this research. Fifty-six plant species belonging to 29 families were successfully established on the afforested sites, while unmanaged tailings had only a few native plant species colonizing the surrounding soils. Almost all plant roots collected were associated to AMF in these sites. The genus
Glomus was the most abundant AMF species found in their rhizosphere; however, the
Acaulospora genus was also observed. Other rhizospheric fungi were identified by 18S rDNA sequencing analysis. Their role in these substrates, i.e. biocontrol, pollutant- and organic matter-degradation, and aides that increase plant metal tolerance is discussed. Our results advance the understanding of fungal diversity in sites polluted with metals and present alternative plants for remediation use.
Rhizospheric fungi and organic matter encourage plant vegetation of tailings by pioneers and colonizing species.
Abstract
Mexico is a center of diversity for pines, but few studies have examined the ectomycorrhizal (ECM) fungal communities associated with pines in this country. We investigated the ECM ...communities associated with Pinus montezumae seedlings and mature trees in neotropical forests of central Mexico and compared their structure and species composition. Root tips were sampled on both planted seedlings and naturally occurring adult trees. A total of 42 ECM operational taxonomic units (OTUs) was found on P. montezumae. Diversity and similarity indices showed that community structure was similar for both plant growth stages, but phylogenetic diversity and Chao-estimated richness were higher for seedlings. Species composition differed between communities. The dominant OTUs belonged to the families Atheliaceae, Cortinariaceae, and Sebacinaceae, although different taxa appeared to colonize seedlings and adults. Only 12 OTUs were shared between seedlings and adults, which suggests that ECM fungi which colonize seedlings are still not fully incorporated into mycelial networks and that ECM taxa colonizing young individuals of P. montezumae are likely to come from fungal propagules. Intra-generic diversity could be an insurance mechanism to maintain forest productivity under stressed conditions. This is the first report describing the abundance of Atheliaceae in tree roots in neotropical ecosystems.
Ectomycorrhizal (ECM) and ectendomycorrhizal fungal species associated with
Pinus montezumae
were recorded in 8 year-old trees established in microcosms and compared with those associated with ...2 year-old trees, in order to determine their persistence over the long-term. Mycorrhizal root tips were morphologically and anatomically characterized and sequenced. The extension of extramatrical mycelium of ECM fungi with long exploration strategies was evaluated. In total, 11 mycorrhizal species were registered. Seven mycorrhizal species were detected on both 2 and 8 year-old pines: Atheliaceae sp.,
Rhizopogon
aff.
fallax
,
R.
aff.
occidentalis
,
Suillus pseudobrevipes
,
Tuber separans
,
Wilcoxina mikolae
and
Wilcoxina rehmii
. One species,
Thelephora terrestris,
was exclusively associated with two year–old seedlings, while
Cenococcum geophilum
, Pezizaceae sp. and Pyrenomataceae sp. were exclusively found on 8 year-old trees. Atheliaceae sp. was the ECM fungal species that presented the most abundant mycelium. Finally, we report one new fungal species of Pezizaceae occurring as a symbiont of
P. montezumae
.
The conservation of geosites in a region can foster its sustainability and develop geotourism. These geosites provide geoeducation, raise people’s awareness on natural hazards, and increase their ...resilience. Low-income cities located in tectonically active areas combine high geohazards with high vulnerability and low sustainability. Geosites in these cities should be a tool to decrease people’s vulnerability and foster sustainable development. Mexico City is an ideal case study for its environmental and social issues and its setting in an active continental volcanic arc. The 1700-year-old Xitle volcano, located in the city’s SW corner, is a small scoria cone that erupted once, feeding an extensive lava field on which > 600,000 people now live. The lavas are very well exposed due to thin soils and extensive quarrying. The Xitle lavas covered the first urban center in the Mexico basin, except for the main pyramid that has become a major archeological site. The cone and lavas have significant geodiversity, sustaining a unique and biodiverse ecosystem. The country’s largest university preserves the lavas in an ecological reserve. We describe four exceptional geosites, assess their values, and discuss their relevance for addressing issues such as nature preservation, environmental sustainability, social inequalities, and natural hazards. The Xitle volcano provides a wide range of benefits for the city that are nonetheless unknown to its inhabitants. We describe ongoing initiatives to disseminate such information, such as the Geopedregal site, and propose ways that this heritage could be further protected and used by the city in a sustainable way.
Ectomycorrhizal (ECM) fungal communities have been relatively poorly documented in neotropical forests. We analyzed the structure and diversity of the ECM resistant propagules present in the soil of ...Mexican neotropical forests dominated by Pinus montezumae. Soil samples were collected under mature P. montezumae, and microcosms were set up with bioassayed seedlings. The ECM propagules were formed by relatively few taxa that were evenly distributed across the sampled area. Some taxa, such as Rhizopogon spp. and Atheliaceae sp., formed an extensive mycelial system, which is likely to confer them with an advantage for seedling colonization. We also compared the species composition of the ECM propagules with the ECM communities previously assessed on the roots of seedlings and adult trees. They were represented by different taxa, although similarity analyses did not detect differences in species occurrence. Only two taxa, belonging to the Atheliaceae family, were shared between field and bioassayed seedlings, whereas 12 taxa were common to field seedlings and adult trees. The lower similarity between bioassayed and field seedlings suggests that fungal taxa found as resistant propagules are not active in mycelial networks in field conditions and that mycorrhizal network-mediated colonization may be prevalent in this neotropical forest.
•Ectomycorrhizal (ECM) propagules in soil were surveyed in a neotropical pine forest.•Most frequent taxa in the ECM propagules were Thelephora, Rhizopogon and Wilcoxina.•Only two species, Atheliaceae sp. 1 and sp. 2, were shared between bioassayed seedlings and field seedlings and adult trees.•The importance of mycorrhizal networks for seedling establishment was presented.
Soil factors influencing ectomycorrhizal (ECM) sporome distribution in neotropical forests dominated by Pinus montezumae were examined at Sierra Chichinautzin, Mexico. Study sites were located on ...three volcanoes of different ages and ECM sporomes were collected during three consecutive years. Inocybe and Laccaria species were preferentially found at the youngest site, while Tricholoma and Russula species showed a more abundant distribution at the oldest site. Total sporome richness was negatively correlated with carbon (C) and nitrogen (N) contents in the soil organic horizon. Canonical correspondence analysis (CCA) was used to investigate the relationships between sporome species and soil variables. The CCA biplot showed that Amanita rubescens, I. fastigiata, and I. geophylla had a strong positive relationship with soil C and N contents, whereas Inocybe sp.4 was negatively related to these variables. This indicates an intra-generic variability in fungal responses to soil factors. The measured soil nutrients influenced species composition patterns, and the differences in sporome distribution evidenced a large degree of community specialization along the soil quality gradient. Together, these data contribute to a better understanding of the ecology of macrofungi in neotropical forests.
Saprophytic fungi are one of the most active decomposers of forest litter, and their diversity may be influenced by the spatial heterogeneity of substrates. We examined the changes in saprophytic ...community structure and composition across a volcanic soil chronosequence, at Sierra del Chichinautzin, Mexico. Saprophytic fungi were collected for three consecutive years at three sampling sites with contrasting soil properties in a volcanic soil chronosequence ranging from 1,835 years B.P. to 10,000 years B.P. Although no significant differences were found in terms of abundance and richness between the three sites, Shannon diversity was higher at the youngest, less-fertile site. The high percentage of site-exclusive species showed that species composition was strongly dependent on the site and therefore on soil parameters. Different saprophytic species had divergent responses to soil variables, but most fungal taxa correlated negatively with the edaphic factors we measured. The highest diversity found at the young, less fertile site may represent an “insurance” mechanism against harsh conditions, since different species are likely to play various ecological functions which may lead to a more efficient degradation of recalcitrant substrates.
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