Research

19 pages, 2330 KiB

Open AccessFeature PaperArticle

Isotria medeoloides, a North American Threatened Orchid: Fungal Abundance May Be as Important as Light in Species Management

by Dennis Whigham, Melissa McCormick, Hope Brooks, Brian Josey, Robert Floyd and Jason Applegate

Plants 2021, 10(9), 1924; https://doi.org/10.3390/plants10091924 - 15 Sep 2021

Cited by 3 | Viewed by 2486

Abstract

The management of endangered or threatened plant species is difficult if protocols are not developed to propagate species for the purpose of restoration or the enhancement of existing populations. The management of endangered and threatened orchids is especially difficult because of the obligate [...] Read more.

The management of endangered or threatened plant species is difficult if protocols are not developed to propagate species for the purpose of restoration or the enhancement of existing populations. The management of endangered and threatened orchids is especially difficult because of the obligate interactions between orchids and orchid mycorrhizal fungi. Isotria medeoloides is a federally threatened forest-dwelling orchid species with a wide distribution in eastern North America. Seeds have not been successfully germinated and current management is based primarily on using subcanopy thinning to increase light in areas where monitoring demonstrates that populations are declining. We report the results of long-term monitoring efforts, canopy thinning, and orchid mycorrhizal fungus abundance studies at two locations in Virginia. The declining populations responded positively to the experimental and natural thinning of the canopy. At one site, the response was the result of understory canopy thinning. At the second site, the response was due to the natural death of a canopy tree. In light of the dramatic increase in fungal abundance following death of the canopy tree, we propose the Fungal Abundance Hypothesis as an additional approach to the management of endangered plant species. The removal of canopy trees in or adjacent to Isotria populations results in an increase in dead belowground biomass (i.e., roots of the dead canopy tree) that provides substrates for microbial growth, including orchid mycorrhizal fungi, that benefit Isotria. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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12 pages, 909 KiB

Open AccessFeature PaperArticle

Epiphytic Orchid Diversity along an Altitudinal Gradient in Central Nepal

by Binu Timsina, Pavel Kindlmann, Sajan Subedi, Subhash Khatri and Maan B. Rokaya

Plants 2021, 10(7), 1381; https://doi.org/10.3390/plants10071381 - 06 Jul 2021

Cited by 11 | Viewed by 4052

Abstract

Epiphytic orchids are common in subtropical forests, but little is known about the factors that determine their diversity. We surveyed two sites (north-facing Phulchowki and south-facing Shivapuri hills), in the sub-tropical forest in the Kathmandu valley, central Nepal. Along five transects per site, [...] Read more.

Epiphytic orchids are common in subtropical forests, but little is known about the factors that determine their diversity. We surveyed two sites (north-facing Phulchowki and south-facing Shivapuri hills), in the sub-tropical forest in the Kathmandu valley, central Nepal. Along five transects per site, spanning an altitudinal gradient of 1525–2606 m a.s.l., we recorded all epiphytic orchids and the host species on which they were growing. The data were analyzed using a generalized linear model (GLM) and redundancy analysis (RDA). Species richness significantly decreased with increasing altitude and was higher in larger hosts and in places with high temperature. Species composition was affected by altitude, distance from the forest edge, host type, and precipitation. This study indicates that the most important factors affecting epiphytic orchid diversity was altitude, even if other factors were associated with patterns in composition. The low-altitude habitats with high species diversity are the best places for epiphytic orchids in this region. The altitudinal species richness and patterns in composition revealed by this study provide a baseline for further studies on epiphytic orchids. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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22 pages, 7259 KiB

Open AccessArticle

Environmental and Management Effects on Demographic Processes in the U.S. Threatened Platanthera leucophaea (Nutt.) Lindl. (Orchidaceae)

by Timothy J. Bell, Marlin L. Bowles, Lawrence W. Zettler, Catherine A. Pollack and James E. Ibberson

Plants 2021, 10(7), 1308; https://doi.org/10.3390/plants10071308 - 28 Jun 2021

Cited by 10 | Viewed by 3226

Abstract

Populations of the U.S. threatened orchid, Platanthera leucophaea, are restricted to fragmented grassland and wetland habitats. We address the long-term (1998–2020) interactive effects of habitat (upland prairie vs. wetland), fire management (burned vs. unburned) and climatic variation, as well as pollination crossing [...] Read more.

Populations of the U.S. threatened orchid, Platanthera leucophaea, are restricted to fragmented grassland and wetland habitats. We address the long-term (1998–2020) interactive effects of habitat (upland prairie vs. wetland), fire management (burned vs. unburned) and climatic variation, as well as pollination crossing effects, on population demography in 42 populations. Our analysis revealed the consistent interactive effects of habitat, dormant season burning, and climatic variation on flowering, reproduction, and survival. Burning increased flowering and population size under normal or greater than normal precipitation but may have a negative effect during drought years apparently if soil moisture stress reduces flowering and increases mortality. Trends in the number of flowering plants in populations also correspond to precipitation cycles. As with flowering and fecundity, survival is significantly affected by the interactive effects of habitat, fire, and climate. This study supports previous studies finding that P. leucophaea relies on a facultative outcrossing breeding system. Demographic modeling indicated that fire, normal precipitation, and outcrossing yielded greater population growth, and that greater fire frequency increased population persistence. It also revealed an ecologically driven demographic switch, with wetlands more dependent upon survivorship than fecundity, and uplands more dependent on fecundity than survivorship. Our results facilitate an understanding of environmental and management effects on the population demography of P. leucophaea in the prairie region of its distribution. Parallel studies are needed in the other habitats such as wetlands, especially in the eastern part of the range of the species, to provide a more complete picture. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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13 pages, 1481 KiB

Open AccessArticle

Protocorm-Supporting Fungi Are Retained in Roots of Mature Tipularia discolor Orchids as Mycorrhizal Fungal Diversity Increases

by Melissa McCormick, Robert Burnett and Dennis Whigham

Plants 2021, 10(6), 1251; https://doi.org/10.3390/plants10061251 - 20 Jun 2021

Cited by 13 | Viewed by 2716

Abstract

Mycorrhizal fungi are critical to understanding the distribution patterns of many plants, but they are especially important for orchids. Some orchids may change the mycorrhizal fungi they use through their lives, either in response to changes in abiotic or biotic conditions, or as [...] Read more.

Mycorrhizal fungi are critical to understanding the distribution patterns of many plants, but they are especially important for orchids. Some orchids may change the mycorrhizal fungi they use through their lives, either in response to changes in abiotic or biotic conditions, or as a result of ontogenetic changes that alter the orchid’s need for fungal nutrition. The temperate terrestrial orchid Tipularia discolor germinates only on decomposing wood, but often persists well after the wood has completely decomposed and has been incorporated into the soil. We used PCR and Sanger sequencing to ask: (1) Do mature T. discolor retain protocorm fungi or are protocorm and adult mycorrhizal fungi mutually exclusive? (2) Are protocorm fungi limited to areas with decomposing wood? (3) Does the abundance of protocorm fungi in the substrate differ between decomposing wood and bare soil? We found that T. discolor retained protocorm fungi into maturity, regardless of whether they were growing in persistent decomposing wood or soil. Protocorm fungi were not restricted to decomposing wood but were more common and abundant in it. We conclude that the mycorrhizal fungi associated with T. discolor change during the ontogeny of individuals. These results highlight the importance of assessing protocorm fungi, in addition to mycorrhizal fungi associating with adult orchids, to understand the conditions needed for orchid germination, growth, and reproduction. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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16 pages, 4439 KiB

Open AccessArticle

Distribution of Orchids with Different Rooting Systems in the Czech Republic

by Zuzana Štípková, Spyros Tsiftsis and Pavel Kindlmann

Plants 2021, 10(4), 632; https://doi.org/10.3390/plants10040632 - 26 Mar 2021

Cited by 10 | Viewed by 2733

Abstract

Understanding diversity patterns along altitudinal gradients and the effect of global change on abundance, distribution patterns and species survival are of the most discussed topics in biodiversity research. Here, we determined the associations of orchid species richness and the degree of their specialization [...] Read more.

Understanding diversity patterns along altitudinal gradients and the effect of global change on abundance, distribution patterns and species survival are of the most discussed topics in biodiversity research. Here, we determined the associations of orchid species richness and the degree of their specialization to specific environmental conditions (expressed by species specialization index) with altitude in six floristic areas in the Czech Republic. We distinguished three basic trends in these relationships: linear, parabolic and cubic. We then determined whether these trends differ between three orchid groups classified by their rooting systems: rhizomatous, intermediate and tuberous. We used distributional data on 69 species and subspecies of terrestrial orchids recorded in the Czech Republic and interpolated them at 100-m intervals along an altitudinal gradient in each floristic area. The trends in both species richness and mean species specialization index differed between the six floristic areas within each of the three orchid groups studied. These patterns are probably strongly influenced by the orography of the country and the distribution of different habitats in the six floristic areas in the Czech Republic. We also found that the most widely distributed orchid group in the Czech Republic are the rhizomatous orchids, followed by intermediate and tuberous ones. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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21 pages, 5228 KiB

Open AccessArticle

Suitability of Habitats in Nepal for Dactylorhiza hatagirea Now and under Predicted Future Changes in Climate

by Bikram Shrestha, Spyros Tsiftsis, Deep Jyoti Chapagain, Chhatra Khadka, Prakash Bhattarai, Neelima Kayastha Shrestha, Marta Alicja Kolanowska and Pavel Kindlmann

Plants 2021, 10(3), 467; https://doi.org/10.3390/plants10030467 - 02 Mar 2021

Cited by 17 | Viewed by 3586

Abstract

Dactylorhiza hatagirea is a terrestrial orchid listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and classified as threatened by International Union for Conservation of Nature (IUCN). It is endemic to the Hindu-Kush [...] Read more.

Dactylorhiza hatagirea is a terrestrial orchid listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and classified as threatened by International Union for Conservation of Nature (IUCN). It is endemic to the Hindu-Kush Himalayan region, distributed from Pakistan to China. The main threat to its existence is climate change and the associated change in the distribution of its suitable habitats to higher altitudes due to increasing temperature. It is therefore necessary to determine the habitats that are suitable for its survival and their expected distribution after the predicted changes in climate. To do this, we use Maxent modelling of the data for its 208 locations. We predict its distribution in 2050 and 2070 using four climate change models and two greenhouse gas concentration trajectories. This revealed severe losses of suitable habitat in Nepal, in which, under the worst scenario, there will be a 71–81% reduction the number of suitable locations for D. hatagirea by 2050 and 95–98% by 2070. Under the most favorable scenario, this reduction will be 65–85% by 2070. The intermediate greenhouse gas concentration trajectory surprisingly would result in a greater reduction by 2070 than the worst-case scenario. Our results provide important guidelines that local authorities interested in conserving this species could use to select areas that need to be protected now and in the future. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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25 pages, 2125 KiB

Open AccessArticle

How to Protect Natural Habitats of Rare Terrestrial Orchids Effectively: A Comparative Case Study of Cypripedium calceolus in Different Geographical Regions of Europe

by Anna Jakubska-Busse, Spyros Tsiftsis, Michał Śliwiński, Zdenka Křenová, Vladan Djordjević, Corina Steiu, Marta Kolanowska, Petr Efimov, Sebastian Hennigs, Pavel Lustyk and Karel (C.A.J.) Kreutz

Plants 2021, 10(2), 404; https://doi.org/10.3390/plants10020404 - 20 Feb 2021

Cited by 13 | Viewed by 4294

Abstract

In this article we present and discuss the main factors that threaten natural populations of Cypripedium calceolus (lady’s slipper orchid) in Europe, and we propose conservation strategies and directions for protective actions of its population on a regional scale. European C. calceolus populations [...] Read more.

In this article we present and discuss the main factors that threaten natural populations of Cypripedium calceolus (lady’s slipper orchid) in Europe, and we propose conservation strategies and directions for protective actions of its population on a regional scale. European C. calceolus populations have decreased significantly in the last two decades, in both number and size. A key result of the present study is an evaluation of the effectiveness of the Natura 2000 network across the European Union (EU) countries. Northern and/or mountainous countries present higher percentages of potentially suitable areas within the Natura 2000 network. Finland and the United Kingdom are the exceptions to this rule. It is predicted that, due to global warming, the coverage of niches suitable for C. calceolus will decrease in countries in which now-healthy colonies exist. However, as plant species can occur in micro-sites with suitable environmental conditions (e.g., microclimate, vegetation, soil factors) which cannot be predicted as suitable at coarser spatial resolutions, conservation efforts should be focused on management of local healthy populations. For the effective protection of C. calceolus in Natura 2000 sites, the participation of experts in botany, including orchid biology, is necessary at several stages. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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15 pages, 1929 KiB

Open AccessArticle

The Impact of Human Pressure and Climate Change on the Habitat Availability and Protection of Cypripedium (Orchidaceae) in Northeast China

by Huanchu Liu, Hans Jacquemyn, Xingyuan He, Wei Chen, Yanqing Huang, Shuai Yu, Yupeng Lu and Yue Zhang

Plants 2021, 10(1), 84; https://doi.org/10.3390/plants10010084 - 02 Jan 2021

Cited by 15 | Viewed by 3331

Abstract

Human pressure on the environment and climate change are two important factors contributing to species decline and overall loss of biodiversity. Orchids may be particularly vulnerable to human-induced losses of habitat and the pervasive impact of global climate change. In this study, we [...] Read more.

Human pressure on the environment and climate change are two important factors contributing to species decline and overall loss of biodiversity. Orchids may be particularly vulnerable to human-induced losses of habitat and the pervasive impact of global climate change. In this study, we simulated the extent of the suitable habitat of three species of the terrestrial orchid genus Cypripedium in northeast China and assessed the impact of human pressure and climate change on the future distribution of these species. Cypripedium represents a genus of long-lived terrestrial orchids that contains several species with great ornamental value. Severe habitat destruction and overcollection have led to major population declines in recent decades. Our results showed that at present the most suitable habitats of the three species can be found in Da Xing’an Ling, Xiao Xing’an Ling and in the Changbai Mountains. Human activity was predicted to have the largest impact on species distributions in the Changbai Mountains. In addition, climate change was predicted to lead to a shift in distribution towards higher elevations and to an increased fragmentation of suitable habitats of the three investigated Cypripedium species in the study area. These results will be valuable for decision makers to identify areas that are likely to maintain viable Cypripedium populations in the future and to develop conservation strategies to protect the remaining populations of these enigmatic orchid species. Full article

(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)

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