To date, there have been only limited attempts to conceptually unify ex situ and in situ approaches as parts of an integrated conservation methodology. This paper is an attempt of such conceptual integration of existing approaches for the efficient conservation of rare and endangered plant species. My integration of available plant conservation biology literature is based on the idea that ecologically significant species genetic variation is of primary importance for plant conservation. This idea is used for providing guidelines about inventory of existing populations, sampling and propagating sampled material, and use of this material in species recovery actions.
Plant conservation biology needs a new approach to cope with the rapid disappearance of species and ecosystems. This paper is an attempt to introduce such an approach via conceptual integration of conservation biology and restoration ecology in what can be called conservation-oriented restoration. Use of this term is limited to cases when restoration is applied to a still-functioning ecosystem, excluding cases when the destroyed ecosystem must be recreated or altered to a desirable state. The paper demonstrates the importance of habitat restoration for the majority of threatened species, and, although it may seem paradoxical, advocates usefulness of threatened plant species for restoration of natural habitats. It is proposed that threatened plant species should become an important part of many restoration projects and be introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. Because the number of potentially suitable locations can be close to zero if we consider only untouched natural habitats as suitable, the introduction sites should include those that require restoration efforts. The available literature is reviewed to show why and how ecological restoration should become an integral part of the conservation biologist's armory.
Plant conservation biology needs a new paradigm to stop ongoing environmental degradation and species loss. This paper provides detailed methodological guidelines for the conceptual integration of conservation biology and restoration ecology through “conservation-oriented restoration” as introduced in a companion paper. Based on the latest theoretical developments in community ecology and vast experience gained by researchers in restoration ecology and conservation biology, this paper provides recommendations, among others, for (i) identification of a reference ecosystem; (ii) making operational species lists for introduction; (iii) choosing optimal restoration in terms of planting design, plant number and density; (iv) collecting, storing and using seeds; and (v) addressing plant–animal interactions.
Four populations of the annual grass Avena sterilis distributed along an aridity gradient in Israel (Mount Hermon, Northern Galilee, Shefela, and the Negev Desert), were studied to (1) reveal a general pattern of seed dormancy and persistence in the soil seed bank in this species; (2) compare seed size and demography of reciprocally introduced seeds and seedlings; and (3) test the adaptive nature of the observed patterns. The steep aridity gradient in Israel represents two parallel clines of environmental productivity (annual rainfall) and predictability (variation in amount and timing of annual rainfall). The four populations examined represented the following environments: (1) desert—low productivity and predictability, drought stress; (2) semi-steppe batha-moderate productivity and predictability; (3) grassland—high productivity and predictability; and (4) mountain—high productivity and predictability but with severe frost stress. The highest proportion of dormant seeds, most sequential germination of the first and the second florets of a spikelet over three years, and highest importance of desiccation tolerance were found at the desert location, consistent with bet-hedging buffering against unpredictability of rainfall and high probability of drought in this environment. Significant population origin by environment interactions were observed for yield and reproductive biomass, but no advantage of local ecotype was detected for these two traits. However, another fitness component, seedling survival, showed not only the interactive effect of origin and locality, but also the superiority of the local ecotype and decreasing fitness rank from indigenous ecotype towards the most environmentally dissimilar ecotype, suggesting local ecotype adaptation of seedlings. There was a genetically determined decrease in seed mass with increase in aridity without concomitant effect of frost. The selective forces that may differentially affect seed size along the aridity gradient are competition, predation intensity, importance of dispersal distance, and bet-hedging against rainfall unpredictability. Further experiments are needed to determine the precise nature of aridity-related evolution of seed size in A. sterilis.
Sergei Volis and Jordi López-Pujol
Uriel N. Safriel, Sergei Volis and Salit Kark
Environmental conditions outside the periphery of a species' distribution prevent population persistence, hence peripheral populations live under conditions different from those of core populations. Peripheral areas are characterized by variable and unstable conditions, relative to core areas. Peripheral populations are expected to be genetically more variable, since the variable conditions induce fluctuating selection, which maintains high genetic diversity. Alternatively, due to marginal ecological conditions at the periphery, populations there are small and isolated; the within-population diversity is low, but the between-population genetic diversity is high due to genetic drift. It is also likely that peripheral populations evolve resistance to extreme conditions. Thus, peripheral populations rather than core ones may be resistant to environmental extremes and changes, such as global climate change induced by the anthropogenically emitted “greenhouse gases”. They should be treated as a biogenetic resource used for rehabilitation and restoration of damaged ecosystems. Climatic transition zones are characterized by a high incidence of species represented by peripheral populations, and therefore should be conserved now as repositories of these resources, to be used in the future for mitigating undesirable effects of global climate change. Preliminary research revealed high phenotypic variability and high genetic diversity in peripheral populations relative to core populations of wild barley and the chukar partridge, respectively.
SERGEI VOLIS, SAMUEL MENDLINGER and DAVID WARD
We compared intra- and interspecific competitive responses of wild barley, Hordeum spontaneum, from four populations originating in distinct environments in Israel. The environments ranged along two parallel gradients of rainfall amount and predictability, from low (desert) to moderate (semi-steppe batha) to high (Mediterranean grassland and mountain, the latter also experiencing frost stress). The target barley plants grew under one of five densities (0, 4, 8, 16, and 32 surrounding plants per bucket) of either barley from the same population or oats (Avena sterilis) from a neutral population. The traits examined included estimates of fitness, reproductive traits, and resource allocation.
The effect of intraspecific competition was stronger than interspecific competition at a high increment of neighbor density (from 4 to 32 neighbors). There was no difference in interspecific competitive responses of plants originating in the four environments at any neighbor density increments, but intraspecific competitive responses of the four ecotypes consistently differed at low competitive intensity (4 neighbors). The superior competitors were the plants originating from Mediterranean grassland, the most favorable with respect to rainfall and abiotic stress (i.e., drought or frost) environment. The plants from the mountain environment, which is highly productive and predictable with respect to rainfall but experiences severe frost stress, were the poorest competitors. Our results are inconsistent with the hypothesis that there is no relationship between competitive ability and environmental favorability. High competitive ability appears to be a distinct property of plants living in favorable environments (i.e., productive, predictable, and without abiotic stress) corresponding to the "competitive" strategy of the C-S-R model. However, in less productive and/or predictable environments, or under conditions of severe abiotic stress, plant features other than ability to tolerate low water or nutrient levels may be more important, with reduced competitive ability as a trade-off.
Emilio Laguna, Simón Fos, Juan Jiménez and Sergei Volis
Since 1998 the Valencian Community (Spain) has pioneered the establishment of plant micro-reserves (PMR), which has resulted in a network currently comprising 299 sites. The PMR are compatible with large protected areas including natural parks (NP, 22 areas). In fact, 73 PMR are included within the NP network (internal subnet of PMR) and 226 PMR are outside NP (external subnet). Here we analyze how the PMR network complements that of NP in capturing rare (RS, twp categories), endemic (ES, three categories) and endangered (TS, four categories) plants. The external subnet increases the number of plant species with territorial protection by 10.8% in RS, 15.8% in ES and 21.0% in TS categories. Additionally, when comparing number of species in the external and internal PMR subnets not shared with the alternative subnet type, the former has higher absolute and relative values for the nine categories analyzed. We propose that the internal network should be increased only to capture populations of the species that are not included in the external subnet.
Sergei Volis, Yong-Hong Zhang, Michael Dorman and Michael Blecher
Knowing the extent and structure of genetic variation in an endangered species is essential for establishing efficient conservation practices. However, the proper use of this information requires understanding the role of habitat-specific selection in genetic structuring. We present a study of population differentiation in an endangered species that utilizes guidelines of recently a proposed quasi in situ conservation approach, i.e. taking into account the scale and spatial pattern of local adaptation since if local adaptation is important, the introduced genotypes must be matched to the local biotic/abiotic conditions. Following this approach, we examined the extent and structure of genetic (AFLP) and phenotypic variation and tested for adaptive significance of this variation in critically endangered Iris atrofusca growing in Israel and Jordan. From these results we propose a sampling design that would (i) preserve species adaptive potential and (ii) insure environmental match of the plant material for relocation, reintroduction or enhancement.
Michael Dorman, Pavel Melnikov, Yuval Sapir and Sergei Volis
Oncocyclus irises (Iridaceae) are endangered plants in Israel, yet with high potential for cultivation as ornamental flowers. However, their high seed dormancy level prevents fast development of germplasm for horticultural reproduction. In this paper we describe in-vitro and in-vivo germination experiments with seeds of Oncocyclus irises from Israel. We examined the effects of (1) mechanical scarification and different growing media on in-vitro seed germination; and (2) soil type, covering, and water amount on in-vivo germination. Seeds showed high dormancy, as hardly any seed germinated in the first year after sowing, and only in the second growing season the germinating fraction was considerable (up to 37%), still only under high humidity conditions. We also report an effective in-vitro forced germination protocol, which employs seed scarification. Following these results for in-vivo germination, and based on the protocol developed for in-vitro germination, we recommend two methods for artificial seed germination. For fast germination, good results from a modest quantity of seeds can be obtained by an in-vitro forced germination. For mass seed propagation, when time is not a limiting factor, the in-vivo procedure can be used, using an artificial soil seed bank and treating those seeds during (at least) two seasons under shade and continuous watering.