The Asian Black Truffle, Tuber indicum, was described based on a collection found in northwestern Himalayan India (Cooke & Massee 1892). This species was then rarely mentioned in the literature until Zhang & Minter (1988) named another species, T. himalayense, based on a part of the same collection. These two Asian Black Truffles or the Chinese Black Truffles, are hardly distinguishable by morphological characters (Wang & Liu 2009), yet recent DNA sequences indicated that both taxa are independent.
This ectomycorrhizal truffle is only distributed in Himalayan Indian and China. It is gastronomically highly appreciated, economically valuable and hence increasingly collected. Since 1990ies, it is increasingly being over-harvested and its environment deteriorated due to the multi-million dollar industry of harvesting and trading Chinese black truffles in southwestern China.
Preliminary global red-list assessment: NT A4bcd (Near Threatened). Possibly also A3bcd.
With a relatively large and distributed population, only criterion A applies. Evaluation period, 50 years (= 3 generations as recommended by Dahlberg and Mueller (2011). The habitat destruction, and associated population decline, is estimated to be exceeding 30% in a 50-year perspective starting from 1990, possible also 50 years from today.
Himalayan India and China
The Asian Black Truffles were unknown internationally until the early 1990s when exports to international markets commenced. In the last about twenty years, ascomata of T. indicum and T. himalayense in southwestern China were collected for export to international markets. Hundreds of tones of the Asian black truffles have been collected from the forest in China annually. Harvesting and trading in Chinese black truffles is a multi-million dollar industry that has brought good income to the local economy and farmers (Wang et al. 2008; Wang & Liu 2009). Unlike in Europe, people in southwestern China have not used trained dogs or pigs to search for the truffles; they use adzes or pickaxes, ploughs or other tools to dig up the soils for searching the truffles, which causes severe damage to the habitat, and often results in the harvest of many immature truffles. The truffle forest floor is entirely ploughed to a depth of 30 cm or more and tree roots are exposed to the air. This destructive harvesting method has led to dramatic changes of soil erosion and microenvironments for truffles (Wang et al. 2008; Wang & Liu 2009).
In the last years, the Asian black truffle harvesting has been moving to forests in the interior of the district (Yamanaka et al. 2000, 2001). Wang et al. (2008) explained that the total production of the Asian black truffles is still increasing because new regions of production are continually being found and exploited. However, local production is declining sharply due to destructive harvesting methods. Wang et al. (2008) showed as an example that more than 20 tons of Asian black truffles were produced annually from Huidong County, Sichuan, before 1993, but only 4–5 tons in 2003. “The damage resulted in sharply declining of the truffle production or no any production at the next few years or forever!” (Wang & Liu 2009). However, no concrete data about population size and trends of the Asian Black truffles are available now-
Population Trend: Decreasing
Form ectomycorrhizae with pine trees (e.g. Pinus yunnanensis, P. armandii, and Keteleeria evelyniana) in calcareous soils at alt. 1800-3000 m in the provinces of Yunnan, Sichuan and Xizang, southwestern China. Truffels are formed at depth of soils of 1-30 cm, and mature in winter. Tuber indicum may also form mycorrhiza with North American pines and complete its life cycle in non-native soils (Bonito et al. 2011).
1. Over collection of mature fruit-bodies has resulted in limited number of sexual ascospores in nature. 2. Many young fruit-bodies were collected before mature, and thus, heterothallic sexual reproduction can not be completed. 3. Soil has been deteriorated due to dig-harvesting practice. 4. Global change especially the climate change.
No effective actions yet. Although a few researchers have been inoculating host plants with the Asian black truffles in the hope to cultivate this truffle in China in the near future, it is still in the early research stages (Geng et al. 2009). To change the destructive harvesting method is quite urgent. To train truffle dogs or pigs for hunting truffles and issue regulations for management of truffle resources has just started in China.
This species complex has received much attention of mycologists in the last 15 years. Various kinds of basic researches, e.g. taxonomy, genetic diversity and genetic structure, and application researches, including “artificial cultivation” through inoculation of the plant hosts, have been conducted. However, data on the trends of populations and effective conservation are still lacking.
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