龙脑香科科

龙脑香科植物是木材市场的重要产品，有的品种还可以提炼芳香油，有的品种是制造胶合板的主要原料。在东南亚原产地，个别品种也因其高大挺拔的姿态，被用作城市绿化树种，胡志明市就有上千棵百年以上的龙脑香科行道树。

分类

龙脑香科一般被分为2个亚科：

柄蕊香亚科 Monotoideae：3属30种：

麦克香属 Marquesia：分布于非洲。

柄蕊香属 Monotes：26种，分布于非洲和马达加斯加。

Pseudomonotes：分布于哥伦比亚的亚马逊河流域

龙脑香亚科 Dipterocarpoideae：是最大的亚科，包括13属470-650种，广泛分布在亚洲南部，以马来群岛西部品种最多，是当地热带雨林的优势树种。

• 桉纳士香属 Anisoptera
• 杯裂香属 Cotylelobium
• 龙脑香属 Dipterocarpus：70种
• 冰片香属 Dryobalanops
• 坡垒属 Hopea：105种
• 新棒果香属 Neobalanocarpus
• 柳桉属 Parashorea
• 娑罗双属 Shorea：360种
• 锡兰香属 Stemonoporus
• 乌普纳香属 Upuna
• 瓦特香属 Vateria
• 塞舌耳香属 Vateriopsis
• 青梅属 Vatica：60种

生长在南美圭亚那高原地带的Pakaraimaea roraimae过去曾被归类于本科，自成Pakaraimoideae亚科，现已知属于半日花科。

Dipterocarpaceae is a family of flowering plants with 22 genera and about 695 known species of mainly lowland tropical forest trees. Their distribution is pantropical, from northern South America to Africa, the Seychelles, India, Indochina, Indonesia, Malaysia and Philippines. The greatest diversity of Dipterocarpaceae occurs in Borneo.

The largest genera are Shorea (196 species), Hopea (104 species), Dipterocarpus (70 species), and Vatica (65 species). Many are large forest-emergent species, typically reaching heights of 40–70 m, some even over 80 m (in the genera Dryobalanops, Hopea and Shorea), with the tallest known living specimen (Shorea faguetiana) 93.0 m tall. Named Menara, 'tower' in Malay, this specimen is a yellow meranti tree. It grows in the Danum Valley in Sabah.

The species of this family are of major importance in the timber trade. Some species are now endangered as a result of overcutting, extensive illegal logging, and habitat conversion. They provide valuable woods, aromatic essential oils, balsam, and resins, and are a source for plywood.

Taxonomy

The family name comes from the type genus Dipterocarpus, which is derived from Greek words δι di "two", πτερόν pteron "wing", and καρπός karpós "fruit". The words combined refer to the two-winged fruit available from trees of that genus; other related genera with winged fruits of more than two are included in the family as well.

Classification

The dipterocarp family is generally divided into two subfamilies:

Dipterocarpoideae: the largest of the subfamilies, it contains 13 genera and about 475 species. Distribution includes the Seychelles, Sri Lanka, India, Southeast Asia to New Guinea, and a large distribution in Borneo, where they form the dominant species in the lowland forests. North Borneo (Brunei, Sabah, and Sarawak) is the richest area in the world for dipterocarp species. The Dipterocarpoideae can be divided morphologically into two groups, and the tribe names Shoreae and Dipterocarpeae are sometimes used, but genetic evidence so far does not support this division:

Valvate - Dipterocarpeae group (Anisoptera, Cotylelobium, Dipterocarpus, Stemonoporus, Upuna, Vateria, Vateriopsis, Vatica). The genera of this group have valvate sepals in fruit, solitary vessels, scattered resin canals, and basic chromosome number x = 11.

Imbricate - Shoreae group (Anthoshorea, Doona, Dryobalanops, Hopea, Neobalanocarpus, Neohopea, Parashorea, Pentacme, Richetia, Rubroshorea, and Shorea). The genera of this group have imbricate sepals in fruit, grouped vessels, resin canals in tangential bands, and basic chromosome number x = 7.

Fossilized arthropods

Some 52-million-year-old amber found in the Gujarat province, India, containing a large amount of fossilized arthropods, was identified as sap from the family Dipterocarpaceae.

Ecology

Dipterocarpaceae species can be either evergreen or deciduous. Species occurring in Thailand grow from sea level to about 1300 m elevation. Environments in which the species of the family occur in Thailand include lowland dipterocarp forest 0–350 m, riparian fringe, limestone hills, and coastal hills.

The dipterocarps have dominated the Borneo lowland rain forests for millions of years.

Conservation and climate change

As the dominant tree in Southeast Asia, the Dipterocarp family has seen extensive study relating to its conservation status. They are a keystone species of the native forests of this region, and are essential to their function and structure.

One study by Pang et al. examined the impacts of climate change and land cover on the distribution of this important tree family in the Philippines. They used species distribution models (SDMs) for 19 species that were projected onto both current and future climate scenarios, with current land cover incorporated as well. They found that the current land cover alone reduced the species distributions by 67%, and 37% in protected areas. On the other hand, climate change reduced species distributions by 16-27% in both protected and unprotected areas. There was also an upward shift in elevation of species distribution as a result of climate change, as habitats changed. They concluded that there was a need to improve protected area planning as refuges for critical species, with SDMs proving to be a useful tool for providing projections that can then be incorporated into this planning process.