Conservation and preservation of rare and endangered Camellia species in the sub-tropical rainforests of Viet Nam and China

G. Orel
National Herbarium of New South Wales,
Royal Botanic Gardens Sydney,
Mrs Macquarie’s Road, Sydney NSW 2000, Australia

First published in the International Camellia Society Journal 2011

Introduction

The southern Annamite Mountains, to which the Da Lat and Lang Biang Plateaus belong, are globally recognised for their high plant biodiversity. Some areas that still contain largely pristine rainforests have been preserved and are still scarcely explored. In addition, isolated areas which occur on the peaks of the mountains within the areas of habitation and crop cultivation house remnant rainforest, which also contains a large diversity of plant species. Thus the highly complex geological, topographic and climatic gradients that are present in this vast eco-region create highly variable forest structures, which contain a wealth of fauna and flora, not seen in other regions of the world (personal observation, Orel 1999-2010, IBBH 2007).
Wet evergreen forests at 600m to 900m elevations are dominated by species of Fagaceae (20 species), Myrtaceae and Lauraceae. Large emergent trees abound, including members of the families Burseraceae, Dipterocarpaceae and Theaceae (Schima crenata Korth.). Lianas form an important component of this forest community. Some 122 mammal species and 410 species of birds have been recognised to date. The lower elevation areas are dominated by wet evergreen forests in mesic sites and semi evergreen forests in drier sites (IBBH 2007). A number of Camellia species (and other Theaceae) can be found virtually from the mountain foothills to elevations of over 1,800m (personal observation, Orel 1999-2010).

The importance of conservation and preservation of currently extant Camellia species on the Da Lat and Lang Biang Plateaus can not be overstated. This relatively numerically small number of ‘wild’ Camellia taxa is presumed to carry genes of great significance. These genes may one day facilitate the historical continuation and perhaps the very survival of some Camellia species and subsequently the large number of existing cultivated Camellia forms, varieties and cultivars. Public awareness and vigilance protects known old and historically valuable Camellia specimens which are rightly deemed to be of great cultural significance. This protection is not afforded to the remnant wild populations of Camellia species that naturally occur in South-East Asia and in China.

Project Camellia (1999-2011 and continuing) was designed to locate, identify, document and conserve currently known and also not yet discovered Camellia species which are still extant in the remnant rainforest areas of Viet Nam, Laos and China.

It should be noted, that some of the most important aspects of rainforest germplasm conservation and preservation, are the processes of verification of the actual existence of the species and the extent of the species’ current geographical distribution.

The verification of this type of data requires concentrated effort over a relatively long period of time employing the latest morphological and molecular techniques, not to mention considerable financial backup.

Materials and Methods

Some 25 Camellia species (Table 1.) from China and Viet Nam were assessed to allow the estimation of the degree of their vulnerability to extinction. To achieve this the current Citation of the IUCN Red List Categories and Criteria (IUCN Red List of Threatened Species 2010) has been utilised. All Camellia species, both in Viet Nam and China, were observed in situ by the author of this paper. The presented data is the summary of the eleven research expeditions to Viet Nam (1999 - 2010) and of the six collection trips to China (2003 - 2006) also undertaken by the author of this work.

Exact and detailed collection of pertinent data was performed during all expeditions (unpublished data, Orel 1995-2010). Selected excerpts of this information are presented in Tables 1. and 2., where information regarding respective provenances, observation dates, the numerical stability of the taxa, population trend estimations and the current IUCN data are presented.

Table 3. contains the long term propagation data (unpublished data, Orel 1995-2010). To promote the use of standard format for the citing of the Red List Categories and Criteria, the IUCN forms of citation were utilised as follows:
Extinct    EX   
Near Threatened    NT    
Extinct in the Wild        EW    
Least Concern     LC
Critically Endangered    CR    
Data Deficient    DD
Endangered         EN    
Not Evaluated     NE
Vulnerable     VU
(IUCN Red List of Threatened Species 2010)
It should be noted that under Section V (the criteria for Critically Endangered, Endangered and Vulnerable plant species), there is a hierarchical alphanumeric numbering system of criteria and sub-criteria. These form an integral part of the Red List assessment and all those that result in the assignment of a threatened category must be specified after the Category. Under the criteria A to C and D under Vulnerable, the first level of the hierarchy is indicated by the use of the numbers (1-4) and if more than one is met, they are separated by means of the ‘+’ symbol. The second level is indicated by the use of the lower-case alphabet characters (a-e). These are listed without any punctuation. A third level of the hierarchy under Criteria B and C involves the use of lower case roman numerals (i-v). These are placed in parentheses (with no space between the preceding alphabet character and start of the parenthesis) and separated by the use of commas if more than one is listed. Where more than one criterion is met, they should be separated by semicolons. The following are examples of such usage.
(IUCN Red List of Threatened Species 2010).
EX    EN B2ab(i,ii,iii)
CR A1cd    VU C2a(ii)
VU A2c+3c    EN A1c; B1ab(iii); C2a(i)
EN B1ac(i,ii,iii)    EN B1ab(i,ii,v)c(iii,iv)
    +2b(i)c(ii,v)  
EN A2c; D    VU B1ab(iii)+2ab(iii)
VU D1+2    EN A2abc+3bc+4abc
CR A2c+3c; B1ab(iii)    B1b(iii,iv,v)c(ii,iii,iv)
    +2b(iii,iv,v)c(ii,iii,iv)  
CR D
VU D2

Results

Table 1.  Analysis of long term data for 25 selected Camellia taxa: provenance, observation dates and the known or observed numerical status  

Table 2.  Analysis of the long term data for 25 selected Camellia taxa:
population trend estimations, current IUCN status and notes

 Table 3.  Long term propagation data, 1999-2010, for 25 selected Camellia taxa:
rootstock used, graftage status, seed germination and cuttings’ status.

Discussion

The majority of scientific data presented in this paper constitutes an integral part of diaries and notes accrued during the more than a decade long observations, of repeatedly visited, Camellia population sites in Viet Nam and China (unpublished data, Orel 1999-2010).

Detailed observations of some 25 reliably identified Camellia species indicated a long-term numerical decline in the majority of observed Camellia populations. The observed numerical decline was the result of several factors, which were identified world wide as generally influencing the plant population sizes of a number of species, at geographically differing sites and over a long period of time (IBBH 2007, GBIF 2010). The indiscriminate clearing of remnant rainforest areas (including those of the mountain tops and in the deep valleys), the relentless rise in indigenous populations, the demands of the respective, rapidly expanding economies and the inauguration of a number of large infrastructure projects, were identified as the main factors for the observed long-term numerical decline not only of Camellia, but also of a large number of other rainforest species (IBBH 2007, GBIF 2010, personal observation, Orel 1999-2010).

Results presented in this paper show a decline in the numbers of adult Camellia plants in 75% of observed wild Camellia species (C. amplexicaulis (Pitard) Cohen-Stuart excluded) (Table 1.). The remaining 25% of taxa have not shown an increase in the number of adult individuals, maintaining the existing status quo. It should be noted that the small seedling plants generated by the seed drop within the periphery of adult plants have not been taken into account. Such young plants seldom survive to adulthood, a situation which can be ascribed to competition in the rainforest with congener seedlings and the seedlings of other plant genera (personal observation, Orel 1999-2010). The well documented decline in the numbers of adult plants, in both unprotected and protected areas, is mostly the result of human activities. The wide-spread clearing of the jungle into short- and long-term usable arable land, fuel collection (logging) and sporadic collection of the plants’ underground parts for medicinal purposes, have a long term, detrimental effect, resulting in diminished seed  and seedling production, which prevents the natural annual regeneration.

The observed numerical decline in the number of adult Camellia individuals was logically reflected in trends that documented the overall population sizes of individual Camellia species. The compiled data (Orel 1999-2010) indicated a decline in population sizes in 80% of the observed species of Camellia (Table 2.). This data was amply supported by the currently available data estimates that were compiled by the IUCN (IUCN Red List of Threatened Species 2010). The IUCN data, collected over many years by the scientific community world wide, documents the estimation of trends in a large number of plant species, including those in genus Camellia. This data shows a dramatic decline. Some 84% of the 25 Camellia species tested are listed as endangered and some 40% as critically endangered (IUCN Red List of Threatened Species 2010).

The importance of naturally occurring wild Camellia species has been recognised as a significant resource for a long period of time (Darling 1973, Morgan 1975). Used by indigenous populations as a food source (tea, cooking oil), an ingredient of various medicinal preparations (poultices, herbal teas) and the source of building materials and fuel, wild Camellia species are of high value (Orel, personal observation 1999-2010).
As documented for a number of rainforest plant genera, it may be presumed that the known (and the so far not found and unidentified) Camellia species carry genes with specific DNA sequences which may become highly significant, should the members of the genus be attacked by hitherto unknown diseases. These specific DNA sequences may be able to confer a full, or partial, disease resistance to a number of pathogens (Darling 1973, Morgan 1975).

The results of so far completed morphological studies (Sealy 1958, Chang 1984, Gao et al 2005, Ming & Bartholomew 2007) and the consequent molecular research (Prince & Parks 2001, Orel & Marchant 2006) consistently indicate close interspecific relationships between the known Camellia species, despite their rather wide geographical distribution (Sealy 1958, Chang 1984). Notwithstanding the distinct phenotypic differences that were found in Camellia taxa, the genotypic differences, as expressed by calculations of genetic distances, appeared to be relatively small (unpublished data, Orel & Marchant 2006). The theoretical existence of genetic closeness was amply supported by the many times tested interspecific graft compatibility in the species of Camellia used (Table 3.). The graft unions that were formed in all successful graft combinations demonstrated the presence of processes of adhesion, proliferation and vascular differentiation across the graft interfaces. By implication, all taxa involved demonstrated close commonality in internal tissues, internal structures and analogous physiological processes. It should be pointed out that successful interspecific grafts between the members of other plant genera are also well-documented and are also considered to be an indication of close genetic and taxonomic relatedness (Cronquist 1961, Manos & Stone 2001, Hartmann et al 1977). The many times repeated grafting experiments (1999-2010) showed that almost 91% of the attempted Camellia grafts were compatible with C. sasanqua rootstocks, whilst over 45% of attempted C. japonica grafts were also successful (Table 3). The development of suitable grafting techniques was achieved by trial and error and experiments with a number of graft types. The ‘whip and tongue’ type grafts proved to be superior to any other type. 

The seed propagation techniques developed over many years only rarely failed, the only limitations being imposed by the inferior quality of the seed (mechanically damaged, seed not ripe, or seed too old and dry), or by fumigation damage (Australian quarantine requirements). As shown in Table 3. attempts to germinate some 20 species of Camellia seeds were successful. The main disadvantages when propagating by seed were the relatively long lead time before an adult, flowering plant can be produced and the high costs connected with the maintenance of such plants.

The few attempts to propagate species Camellia by cuttings were not as successful (Table 3.). This may be ascribed to a number of factors, the main obstacle being the fumigation techniques and their destructive influence on propagation materials. The Australian Quarantine Service (AQIS) are required by law to follow the given fumigation protocols in order to prevent a number of plant diseases entering Australia. In consequence several experimental trials are under way in Viet Nam (on the premises of the International Camellia Garden near Da Lat, Lam Dong Province). Here fresh, semi-mature cuttings of several Camellia species were used. The available results so far indicate that the grafting methods employed may still be the preferred and the most successful method of Camellia propagation available.

Propagation results presented in this paper may be considered significant in terms of propagation of the numerically small wild Camellia populations, many of which face imminent extinction (Orel, personal observation 1999-2010, IUCN Red List of Threatened Species 2010). Due to the population pressures, the ever-expanding economies, the very large and sometimes discontinuous range of distribution, the difficulties of access that are due to mountainous terrain and the restrictions of time and finances, it will be not possible to protect and preserve the populations of all wild Camellia species. Further, the numerically small populations of some Camellia species, e.g. C. piquetiana (Pierre ex Lanessan.) Sealy, C. dongnaienss Orel, C. cucphuongensis Ninh & Rosmann, C. maiana Orel, C. rosmannii Ninh, C. azalea Wei, C. cattienensis Orel, C. tonkinensis (Pitard) Coh-Stuart, C.  flava (Pitard) Sealy and C. luteocerata Orel, are known from a single location only and as such are highly vulnerable. Should any ‘unforseen circumstances’ occur these Camellia populations may be lost to us virtually overnight. Thus the cultivation of these and other wild Camellia species may become the only means of their preservation. It is a well-known fact that most of the wild Camellia species are quite inaccessible, not only to the general public, but also to plant breeders and Camellia enthusiasts. The small community of plant researchers, so far, have been unable to raise the profile of the wild Camellia species. The public at large is mostly unaware of the endangered status of these valuable plants and so they remain an undervalued natural resource.


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