RELICT HUMID TROPICAL FOREST IN MEXICO PROMOTES DIFFERENTIATION IN BARRED WOODCREEPERS Dendrocolaptes (AVES: FURNARIIDAE)

Zootaxa ◽  
2020 ◽  
Vol 4780 (2) ◽  
pp. 307-323
Author(s):  
ADOLFO G. NAVARRO-SIGÜENZA ◽  
R. CARLOS ALMAZÁN-NÚÑEZ ◽  
L. ENRIQUE SÁNCHEZ-RAMOS ◽  
M. FANNY REBÓN-GALLARDO ◽  
ENRIQUE ARBELÁEZ-CORTÉS

Humid tropical forests in Mesoamerica are distributed along the Atlantic slope and, in scattered locations, along the Mexican Pacific slope. These poorly explored Mexican forests include microendemic bird species. Two species in the genus Dendrocolaptes occur in lowland and foothill humid tropical forests of Mesoamerica. One of these, D. sanctithomae, is comprised of four subspecies, of which the two that occur in Mexico, D. s. sanctithomae and D. s. sheffleri, are distinctly different morphologically, and the latter is a poorly known microendemic taxon of the Mexican Pacific humid tropical forest in the Sierra Madre del Sur. We used both nuclear (nDNA) and mitochondrial DNA (mtDNA) to evaluate the genetic variation of D. sanctithomae in Mexico, and complemented this with a quantitative analysis of phenotypic traits. We also conducted analyses of environmental niche models to test the hypothesis of niche differentiation of D. s. sheffleri from other taxa of D. sanctithomae. Our phylogenetic reconstructions of mtDNA consistently recovered D. s. sheffleri and D. s. sanctithomae as reciprocally monophyletic, while they shared alleles of nDNA. These mtDNA differences are comparable with differences reported between other Dendrocolaptes sister-taxa pairs. Our analysis of phenotypic traits also indicated that the taxa differ in measurements of hallux and feather barring. In contrast, niche differentiation tests suggest that the niches of both taxa are more similar than expected by chance. Our evidence leads us to propose species status for D. sheffleri. This is an additional example of recent speciation in Mexico that indicates active and peripatric evolutionary differentiation in the northern Neotropics. 

2019 ◽  
Author(s):  
Yang Lin ◽  
Avner Gross ◽  
Christine S. O'Connell ◽  
Whendee L. Silver

Abstract. The strong phosphorus (P) sorption capacity of iron (Fe) and aluminum (Al) minerals in highly weathered, acidic soils of humid tropical forests is generally assumed to be an important driver of P limitation to plants and microbial activity in these ecosystems. Humid tropical forest soils often experience fluctuating redox conditions that reduce Fe and raise pH. It is commonly thought that Fe reduction generally decreases the capacity and strength of P sorption. Here we examined the effects of 14-day oxic and anoxic incubations on soil P sorption dynamics in humid tropical forest soils from Puerto Rico. Contrary to the conventional belief, soil P sorption capacity did not decrease under anoxic conditions, suggesting that soil minerals remain strong P sinks even under reducing conditions. Sorption of P occurred very rapidly in these soils, with at least 60 % of the added P disappearing from the solution within six hours. Estimated P sorption capacities were one order of magnitude higher than the soil total P contents. However, the strength of P sorption under reducing conditions was weaker, as indicated by the increased solubility of sorbed P in NaHCO3 solution. Our results show that highly weathered soil minerals can retain P even under anoxic conditions, where it might otherwise be susceptible to leaching. Anoxic events can also potentially increase P bioavailability by decreasing the strength, rather than the capacity, of P sorption. These results improve our understanding of the redox effects on biogeochemical cycling in tropical forests.


2020 ◽  
Vol 98 (4) ◽  
pp. 441-467
Author(s):  
Consuelo Medina-García ◽  
Alejandro Velázquez ◽  
Joaquin Giménez de Azcárate ◽  
Miguel Ángel Macías-Rodríguez ◽  
Alejandra Larrazábal ◽  
...  

Background: seasonally dry tropical forests are considered critical and important ecosystems because they harbor exceptional biological diversity. Mexico lacks sound phytosociological studies of Seasonally Dry Tropical Forest and Michoacán is no exception. The present study may be regarded the first phytosociological in most of the Mexican pacific coast where seasonally dry tropical forests occurs. Questions/Objective: We aimed at describing the representative plant associations of the seasonally dry tropical forest, distributed on western Michoacán and to provide a sintaxonomic classification framework based on the floristic differentiation of the recognized communities and highlight its phytocenotic diversity. Study site and dates: Estado de Michoacán; 20 years. Methods: A total of 82 phytosociological inventories were conducted. Data were submitted to multivariate two-way indicator species analyses to depict plant communities and their ecological affinities. Results: From its analysis and interpretation, nine plant groups were differentiated, of which all but one was given the rank of association, which are Lysilomo acapulcensis–Heliocarpetum terebinthinacei, Ceibo aesculifoliae–Lysilometum divaricatae, Caesalpinio platylobae-Cordietum elaeagnoidis, Cochlospermo vitifolii-Lueheetum candidae, Lysilomo divaricatae-Cordietum elaeagnoidis; Stenocereo quevedonis-Cordietum selerianae, Guazumo ulmifoliae-Cordietum elaeagnoidis¸ Lonchocarpo huetamoensis-Cordietum elaeagnoidis and the community of Spondias purpurea-Cochlospermum vitifolium. Conclusions: Comparative floristic and structural profiles among plant communities permitted us to distinguish their bioclimatic relationships. Diagnostic species representative of all plant associations were selected and used for sintaxonomic nomenclature.  Plant associations were finally array along bioclimatic and altitudinal gradients and showed in arranged phytosociological tables. The plant association/community’descriptions permitted to compare structural physiognomy, floristic composition, ecological affinities, distribution patterns and bioclimatic liaison among them.


2020 ◽  
Vol 17 (1) ◽  
pp. 89-101 ◽  
Author(s):  
Yang Lin ◽  
Avner Gross ◽  
Christine S. O'Connell ◽  
Whendee L. Silver

Abstract. The strong phosphorus (P) sorption capacity of iron (Fe) and aluminum (Al) minerals in highly weathered, acidic soils of humid tropical forests is generally assumed to be an important driver of P limitation to plants and microbial activity in these ecosystems. Humid tropical forest soils often experience fluctuating redox conditions that reduce Fe and raise pH. It is commonly thought that Fe reduction generally decreases the capacity and strength of P sorption. Here we examined the effects of 14 d oxic and anoxic incubations on soil P sorption dynamics in humid tropical forest soils from Puerto Rico. Contrary to the conventional belief, soil P sorption capacity did not decrease under anoxic conditions, suggesting that soil minerals remain strong P sinks even under reducing conditions. Sorption of P occurred very rapidly in these soils, with at least 60 % of the added P disappearing from the solution within 6 h. Estimated P sorption capacities were much higher, often by an order of magnitude, than the soil total P contents. However, the strength of P sorption under reducing conditions was weaker, as indicated by the increased solubility of sorbed P in NaHCO3 solution. Our results show that highly weathered soil minerals can retain P even under anoxic conditions, where it might otherwise be susceptible to leaching. Anoxic events can also potentially increase P bioavailability by decreasing the strength, rather than the capacity, of P sorption. These results improve our understanding of the redox effects on biogeochemical cycling in tropical forests.


Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 734
Author(s):  
Xiankai Lu ◽  
Qinggong Mao ◽  
Zhuohang Wang ◽  
Taiki Mori ◽  
Jiangming Mo ◽  
...  

Anthropogenic elevated nitrogen (N) deposition has an accelerated terrestrial N cycle, shaping soil carbon dynamics and storage through altering soil organic carbon mineralization processes. However, it remains unclear how long-term high N deposition affects soil carbon mineralization in tropical forests. To address this question, we established a long-term N deposition experiment in an N-rich lowland tropical forest of Southern China with N additions such as NH4NO3 of 0 (Control), 50 (Low-N), 100 (Medium-N) and 150 (High-N) kg N ha−1 yr−1, and laboratory incubation experiment, used to explore the response of soil carbon mineralization to the N additions therein. The results showed that 15 years of N additions significantly decreased soil carbon mineralization rates. During the incubation period from the 14th day to 56th day, the average decreases in soil CO2 emission rates were 18%, 33% and 47% in the low-N, medium-N and high-N treatments, respectively, compared with the Control. These negative effects were primarily aroused by the reduced soil microbial biomass and modified microbial functions (e.g., a decrease in bacteria relative abundance), which could be attributed to N-addition-induced soil acidification and potential phosphorus limitation in this forest. We further found that N additions greatly increased soil-dissolved organic carbon (DOC), and there were significantly negative relationships between microbial biomass and soil DOC, indicating that microbial consumption on soil-soluble carbon pool may decrease. These results suggests that long-term N deposition can increase soil carbon stability and benefit carbon sequestration through decreased carbon mineralization in N-rich tropical forests. This study can help us understand how microbes control soil carbon cycling and carbon sink in the tropics under both elevated N deposition and carbon dioxide in the future.


Author(s):  
Moses Mulwa ◽  
Mike Teucher ◽  
Werner Ulrich ◽  
Jan Christian Habel

AbstractTropical forests suffer severe habitat destruction. Thus, tropical forests frequently consist today of only a few small remnants that are often embedded within a matrix of agricultural fields and tree plantations. Forest specialist species have experienced severe population declines under these circumstances. We studied bird communities based on census plots set up in a near-natural forest block, as well as degraded forest patches, tree plantations, and agricultural fields, across the Taita Hills in southern Kenya. We classified each bird species according its ecology and behavior. We quantified the land cover and landscape configuration around each census plot. Typical forest species were mainly observed in the near-natural forest block, and to a lower extent in degraded forest patches. Plantations were almost devoid of birds. Bird communities of small forest fragments were more similar to that of agricultural land than the near-natural forest block. Most frugivorous, insectivorous and nectarivorous birds occurred in forest habitats, while granivorous bird species dominated the bird communities of agricultural land. The surrounding landscape had a marginal impact on bird species composition at local sites. Our study showed that the preservation of near-natural cloud forest, including small forest patches, is essential for the conservation of forest-dependent species, and that plantations do not serve as surrogate habitats.


2008 ◽  
Vol 105 (27) ◽  
pp. 9439-9444 ◽  
Author(s):  
M. C. Hansen ◽  
S. V. Stehman ◽  
P. V. Potapov ◽  
T. R. Loveland ◽  
J. R. G. Townshend ◽  
...  

2015 ◽  
Vol 25 (4) ◽  
pp. 451-465 ◽  
Author(s):  
ESTEBAN BOTERO-DELGADILLO ◽  
NICHOLAS BAYLY ◽  
CAMILA GÓMEZ ◽  
PAULO C. PULGARÍN-R. ◽  
CARLOS ANDRÉS PÁEZ

SummaryThe Santa Marta Foliage-gleaner Automolus rufipectus is one of 19 endemic bird species found in the Sierra Nevada de Santa Marta (SNSM) in northern Colombia but until recently it was considered a sub-species of the Ruddy Foliage-gleaner Automolus rubiginosus. Consequently, published information on its distribution and ecology is lacking, and while it is classified as near- threatened, this designation was based on limited quantitative data. To improve our knowledge of the Santa Marta Foliage-gleaner’s geographical distribution, elevation range, population density, habitat use and conservation status, we analysed both historical and recent site locality records and carried out variable distance transects within forested habitats and shade coffee plantations. We modelled the environmental niche of the species and subsequently estimated its extent of occurrence and area of occupancy, as well as population size. Our results consistently showed that the distribution of the Santa Marta Foliage-gleaner is more restricted than previously considered, both geographically and by elevation (we redefine elevation range as 600–1,875 m). This suggests that the species is more at risk of habitat transformation and combined with our estimates of population size (< 10,000 individuals), it is likely that the species will be uplisted to a higher threat category. More positively, and contrary to published accounts, we found that approximately 40% of the species’ range lies within protected areas. Nevertheless, we recommend the implementation of strategies to maintain forest cover on the western flank of the SNSM and further research to better define the species’ habitat needs and population dynamics.


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