Spyros Tsiftsis

Elevational gradient of vascular plant species richness and endemism in Crete--the effect of post-isolation mountain uplift on a continental island system.

Understanding diversity patterns along environmental gradients and their underlying mechanisms is a major topic in current biodiversity research. In this study, we investigate for the first time elevational patterns of vascular plant species richness and endemism on a long-isolated continental island (Crete) that has experienced extensive post-isolation mountain uplift. We used all available data on distribution and elevational ranges of the Cretan plants to interpolate their presence between minimum and maximum elevations in 100-m elevational intervals, along the entire elevational gradient of Crete (0–2400 m). We evaluate the influence of elevation, area, mid-domain effect, elevational Rapoport effect and the post-isolation mountain uplift on plant species richness and endemism elevational patterns. Furthermore, we test the influence of the island condition and the post-isolation mountain uplift to the elevational range sizes of the Cretan plants, using the Peloponnese as a continental control area. Total species richness monotonically decreases with increasing elevation, while endemic species richness has a unimodal response to elevation showing a peak at mid-elevation intervals. Area alone explains a significant amount of variation in species richness along the elevational gradient. Mid-domain effect is not the underlying mechanism of the elevational gradient of plant species richness in Crete, and Rapoports rule only partly explains the observed patterns. Our results are largely congruent with the post-isolation uplift of the Cretan mountains and their colonization mainly by the available lowland vascular plant species, as high-elevation specialists are almost lacking from the Cretan flora. The increase in the proportion of Cretan endemics with increasing elevation can only be regarded as a result of diversification processes towards Cretan mountains (especially mid-elevation areas), supported by elevation-driven ecological isolation. Cretan plants have experienced elevational range expansion compared to the continental control area, as a result of ecological release triggered by increased species impoverishment with increasing elevation.

Distribution Patterns and Conservation Perspectives of the Endemic Flora of Peloponnese (Greece)

An inventory of the endemic vascular plants of the Peloponnese (395 species and subspecies) has been created based on literature, herbarium and field data. Endemics’ distribution patterns, altitudinal distribution and habitat specificity were investigated. A rarity score for each endemic has been calculated based on its population size, geographic range and habitat specificity. The main mountainous areas of the Peloponnese are largely congruent to the hotspots of endemism. Altitudinal range and niche breadth of the endemics were positively correlated to their range size. The elevational gradient of the endemic species richness showed a hump-shaped pattern, in contrast to the monotonically decreasing pattern of total species richness. Endemic species were found to support boundary theory, while total species richness distribution followed the Rapoport’s elevational rule. The elevational distribution of the average rarity score and the average weighted threat of the endemics resulted in low values for mid-elevation intervals and increased values for low and high altitude areas, indicating that conservation efforts should focus on the two extremes of the elevational gradient. Area prioritization methods were applied using a rarity/complementarity based algorithm with two species weighting schemes. Their results were largely congruent confirming the significance of the main mountainous areas for the conservation of the endemics. Spatial overlap among selected grid cells using the rarity/complementarity analysis and Natura 2000 network was found to be low. Our results revealed the conservation importance of at least one new area located on Kythera Island.

Identifying important areas for orchid conservation in Crete

Crete is especially rich in orchids and their distribution is well known and documented by many floristic accounts. This information, however, is yet to be used to set conservation plans and priorities. We used MaxEnt incorporating both published and unpublished distribution data together with environmental variables to predict the potential distribution of orchids on Crete. The resulting probabilistic maps of species occurrence were used to identify the important areas for orchid conservation on the island. Sites prioritization was performed by applying a species weighting scheme, which was based on species niche breadth. The existence of ecological patterns determining site prioritization was determined using a regression tree analysis based on environmental variables and scores derived from Zonation analysis. The high importance sites were found on Mts Thripti, Ida and Lefka Ori, as well as at low altitude areas east of Heraklion and at the easternmost part of the island. Most of the variation in the site scores was explained by geological substrate, latitude and altitude. Based on the regression tree analysis, sites with the highest scores were at medium and high altitude areas, which are located at the interior of the island. These areas have soils mainly derived from limestones, ophiolites and deposits of calcareous rocks. The lack of a significant effect of vegetation type in explaining the distribution of high importance areas highlights the need for the establishment of micro-reserves for the conservation of orchids in Crete. Finally, endangered orchid species in need of specific conservation actions are indicated.

Ecology of the orchid Goodyera repens in its southern distribution limits

Abstract Goodyera repens, a species of central and northern Europe, forms large populations in the Scotch pine forests in some areas of Mt Rhodopi (NE Greece), while it is completely absent in other areas with the same habitat type. The present study aims to investigate the ecological factors that constitute a barrier in the distribution of G. repens in its southernmost distribution limit. Data from 65 localities were sampled and chemical soil parameters were measured. Using the WorldClim database, the summer maximum temperatures and precipitation values were extracted. Binary logistic regression was used to determine the variables that best explain the distribution of G. repens. The data have been found to fit the model in a significant manner, and the independent variables significantly explaining the probability of G. repens being present were phosphorus, copper, and zinc. The results indicate that the distribution of G. repens is indirectly affected by soil variables through the establishment of mycorrhizal symbiosis. Furthermore, its distribution is found to be negatively correlated with the nutrient content of the soil. The high habitat specificity of the species and its sensitivity to soil nutrient status makes it a convenient indicator for monitoring the consequences of vegetation succession on forest biodiversity.

Identifying areas of high importance for orchid conservation in east Macedonia (NE Greece).

The establishment of a network of reserves is of fundamental importance to the loss of biodiversity. Seven different area selection methods for the establishment of a reserve network were applied in the present study: (a) 5% cut-off value of the grid cells with the highest species richness or conservation value, (b) complementarity analysis using as criteria species richness or conservation value or rarest species richness, and (c) mixed complementarity analysis using as criteria species richness or conservation value. These methods were applied in the orchid taxa of east Macedonia. The conservation values of taxa were estimated on the basis of regional rarity, broad-scale rarity, and species specialization. The spatial overlap between the resulting networks and the Natura 2000 network of the study area was assessed. Furthermore, the efficiency of the latter network to protect the orchid taxa of the study area was examined. Our results suggest that: (a) a multiscale estimation of rarity is necessary for the unbiased estimation of species conservation values; (b) species specialization adds valuable ecological information to the assessment of taxa conservation values; (c) complementarity and mixed complementarity analyses on species richness or conservation value safeguard all the taxa of the region; (d) complementarity analysis on the basis of the richness of the rarest species safeguards all the rarest taxa, but not the total number of the remaining taxa; (e) the 5% cut-off value on species richness or conservation value fails to protect all the taxa of the region, including a large number of the rarest taxa; and (f) the Natura 2000 network, despite its large coverage in the study area, fails to safeguard all the taxa, including some of the rarest.

Factors affecting the distribution and abundance of orchids in grasslands and herbaceous wetlands

Grasslands, wet meadows, fens, bogs, and marshes represent important ecosystems that host many orchid species. However, research on the joint effect of the multi-scalar abiotic drivers on orchid distribution and abundance in these habitats is limited. In this study, we investigated factors associated with the occurrence and abundance of 42 orchid taxa in grasslands and herbaceous wetlands of 29 mountains and the surrounding low altitude areas in western Serbia (eastern Dinaric Alps, southeastern Europe). Niche analysis of orchids was performed using outlying mean index analysis (OMI). In addition, we used similarity profile analysis (SIMPROF) to classify orchid taxa into ecological groups, multi response permutation procedure (MRPP) to analyse the differences in orchid composition between vegetation types, and indicator species analysis (ISA) to detect orchids with an affinity to a certain type of vegetation and geological bedrock. The most important gradients that separate orchids within the sampled environmental conditions were moisture, temperature, altitude and soil pH. Moreover, this study underlines the importance of certain vegetation types and geological bedrocks in determining the distribution and abundance of orchids. In total, eight ecological groups of orchids were distinguished. The results have shown that 11 orchid taxa are indicators of specific vegetation types, whereas 13 orchid taxa are indicators of specific bedrock types. The study area provides suitable conditions for survival of some rare and endemic orchid species that have southern limits of their distribution in this part of southeastern Europe. The study suggests that the joint effect of ecological factors, especially vegetation communities and bedrock types, is important to consider in the planning and management of orchid species conservation.

Niche analysis of orchids of serpentine and non-serpentine areas: Implications for conservation

Orchids are known for their species richness, intriguing ecology, rarity and the fact that they grow in almost all terrestrial ecosystems. Although numerous studies about their ecology have been carried out concerning calcareous areas, little is known about orchids that occur in serpentine habitats. The aim of this study was to investigate the ecological preferences of orchids in serpentine and non-serpentine areas on the model of the Valjevo Mountain Range (W Serbia). Niche analysis of orchids was performed using outlying mean index analysis. Data concerning geographical coordinates, altitude, habitat type, inclination, bedrock type, light regime, soil moisture, acidity, nitrogen and temperature were used as explanatory variables. Data of 33 orchid taxa from 407 localities were analysed. The most important gradients that govern orchid distribution were geological bedrock, light regime and temperature. The results have shown that only Anacamptis morio and Gymnadenia conopsea have statistically significantly larger populations on serpentine compared with non-serpentine bedrocks. This study highlights the importance of serpentine habitats as orchid habitats, bearing in mind the occurrence of rare species and species which were found exclusively in serpentine habitats.

Role of way of life, latitude, elevation and climate on the richness and distribution of orchid species

We are experiencing climate warming that is likely to affect all regions worldwide, although in a different manner, when its consequences (e.g. increase of temperature, lower seasonality, lower environmental stochasticity) are considered. Thus, our prediction of how global change will affect distribution and survival of species can be estimated by using our knowledge, how species richness and distribution is related with latitude and elevation. We used 193 terrestrial orchid species and subspecies as an example and we classified them according to their root system. This trait represents the evolution of strategies for underground storage of resources and resource acquisition as well as a characteristics that can be described as a life history trait. Classification of orchid life history traits that focus on belowground strategies has never been examined in a macroecological study. We then explored the associations between species richness, mean niche breadth and mean distribution on one hand and selected predictors on the other hand, using regression techniques for all orchids, and then for their subsets with different root systems. The predictive power, as well as the significance of the predictors, was also tested using polynomial second order generalized linear models. Species richness for the three belowground strategies was significantly affected by the predictors, whereas their mean niche breadth and mean distribution were largely dependent on their evolutionary history. The correlations of mean niche breadth and mean distribution with maximum elevation, latitude and longitude were significant for all orchid taxa and their subsets. All the variables together accounted for almost 50% or more of the variance in each of the subsets. The maximum elevation was the most significant factor for rhizomatous and intermediate orchids, whereas minimum temperature in the coldest month was highly significant for the tuberous orchids. Spatial distribution of Greek orchids is associated with a combination of elevation, latitude and climate. The distributions of rhizomatous and intermediate orchids are mainly associated with the orographic configuration of Greece, whereas the tuberous orchids are widely distributed in the southern, central and north-western areas of Greece, where most of them are limited by the harsh winter climate.

Chloroplast DNA variation in Epipactis atrorubens populations from northern Greece

Abstract Epipactis Zinn. is a highly diverse genus, with numerous taxa naturally occurring throughout Europe. While their morphological variability has resulted in contradictory opinions about their taxonomy, the knowledge of the genetic variation of many of its species is limited. Such an example is E. atrorubens in the Balkan Peninsula. In this work, the cpDNA variation of seven E. atrorubens populations from northern Greece and of one population from Germany has been investigated by means of PCR-RFLP markers. Two regions of the cpDNA were studied (trnH-psbA, trnL intron) and four PCR-RFLP markers were employed (trnH-psbA/HaeIII, trnH-psbA/HinfI, trnH-psbA/VspI, trnL/MboI), which have revealed variation in other Epipactis species. The results demonstrate limited genetic variability in the studied populations, as only one haplotype was present in all the populations (both Greek and German), with the exception of Mt. Menikion (Greece) where a second haplotype was also recorded. This limited variation may be attributed to the properties of the genetic markers involved, to the conserved status of the two cpDNA regions in this species or to factors related to the biology and evolutionary history of E. atrorubens. The presence of a second haplotype only in Mt. Menikion could be attributed to a hybridisation event in the past and/or to the potential existence of a glacial refugium on this mountain.

The effects of presence/absence vs. continuous suitability data on reserve selection

Species distribution models are widely applied for generating the appropriate data for designing networks of reserve systems. The aim of the present study is to compare the use of presence/absence and continuous suitability data, derived from species distribution models, in reserve selection, and to detect any systematic trends in the reserve networks produced on the basis of these two types of data. The MAXENT model was applied to predict orchids’ potential distribution in east Macedonia (northeast Greece). One presence/absence and one with suitability values data set was made and used in the ZONATION decision support tool in order to prioritize the cells of the study area for inclusion in a reserve network. In the selection procedure, species weighting has been applied by using the species specialization index. Results show that the presence/absence data set favors the selection of cells with more extreme climatic conditions and more distant from the mean habitat of the study area. Furthermore, the continuous suitability data set provides higher suitability values for the specialist taxa in comparison with the presence/absence data set, while the opposite is happening for the generalist taxa. The present study reveals that the suitability data outperform the presence/absence data in reserve selection because: (a) they better represent the average environmental conditions of the study area in the selected networks; (b) they ensure higher suitability values for the specialist species, which are more prone to extinction in the future; and (c) they take full advantage of species weighting according to their habitat specificity.