Contrasting effects of invasive rabbits on endemic plants driving vegetation change in a subtropical alpine insular environment

Alpine ecosystems on islands are among the most isolated on Earth, leading to very high rates of endemism. Endemic species on oceanic islands are particularly vulnerable to invasive herbivores. In the alpine zone of Tenerife, which harbors a unique endemic flora, the dominance pattern of the two most dominant species in our days (Spartocytisus supranubius and Pterocephalus lasiospermus) has shifted in the last few decades, which may be a result of increasing rabbit pressure. In this study we explore how rabbits affect the population structure, soil nutrient composition and regeneration of our two target endemics within Teide National Park. For this purpose, we established 90 plots at 30 locations. Within 13 locations we sampled permanent exclosure plots that were established between 7 and 12 years before sampling, applying three treatments (full herbivory, rabbit herbivory and no herbivory). At one site we collected 80 soil samples to evaluate changes in soil chemistry and plant growth using a greenhouse experiment. Our results show that rabbits have a negative effect on the population structure of S. supranubius, while the contrary occurs with P. lasiospermus. Rabbit presence alters soil chemistry leading to a decline in nitrogen, which affects growth in both species. The presence of rabbits leads to a dominance shift in these two keystone endemic species, altering dominance patterns in the summit scrub of Tenerife. The decline of S. supranubius could represent the example of many endemic species of this system. Thus, we call for an immediate control of rabbit population (< 0.5 rabbits/ha) to protect this unique alpine endemic flora.     

Climate change causes rapid collapse of a keystone shrub from insular Alpine ecosystems

Increasing species regression speeds are one of the consequences of global warming, which affect both rare and abundant species. However, long-term monitoring data are rarely available to understand the effects of global warming. Alpine ecosystems on islands are some of the most unique in terms of species composition around the world, with high proportions of endemics. Yet, they are some of the most threatened by climate change. In such areas, global warming causes the invasion of other species that move upwards from ecosystems at lower elevations, which exacerbates climate change impact on these areas. Obtaining fine-scale data on decline rates in keystone species in these areas is essential to understand the degradation processes underway in high mountain systems. This study uses historical aerial images to analyse at a fine-scale the rate of decline of a keystone endemic species, Spartocytisus supranubius (L. f.) Christ ex G. Kunkel, in Tenerife (Canary Islands). Fifty plots were randomly selected in Teide National Park to evaluate the area occupied by living individuals of this species using image segmentation techniques. We conclude that the dominant species in this area, S. supranubius, underwent a mean decline over 32 years between 28.7 and 41.0, depending on whether we consider the observed or interpolated data. Our results suggest that we are facing a possible collapse of the broom and allow us to propose listing this species as vulnerable, according to the IUCN criteria of threatened species. The regression in coverage was negatively correlated with temperature and positively with precipitation.     

Phylogenetic relatedness and plant invader success across two spatial scales

Aim  Successful invaders often possess similar ecological traits that contribute to success in new regions, and thus under niche conservatism, invader success should be phylogenetically clustered. We asked if the degree to which non-native plant species are phylogenetically related is a predictor of invasion success at two spatial scales.
Location  Australia – the whole continent and Royal National Park (south-eastern Australia).
Methods  We used non-native plant species occupancy in Royal National Park, as well as estimated continental occupancy of these species from herbarium records. We then estimated phylogenetic relationships using molecular data from three gene sequences available on GenBank ( matK , rbcL and ITS1 ). We tested for phylogenetic signals in occupancy using Blomberg's K .
Results  Whereas most non-native plants were relatively scarce, there was a strong phylogenetic signal for continental occupancy, driven by the clustering of successful species in Asteraceae, Caryophyllaceae, Poaceae and Solanaceae. However, we failed to detect a phylogenetic signal at the park scale.
Main Conclusions  Our results reveal that at a large spatial scale, invader success is phylogenetically clustered where ecological traits promoting success appear to be shared among close relatives, indicating that phylogenetic relationships can be useful predictors of invasion success at large spatial scales. At a smaller, landscape scale, there was no evidence of phylogenetic clustering of invasion success, and thus, relatedness plays a much reduced role in determining the relative success of invaders.     

Invasion or retreat? The fate of exotic invaders on the northern prairies, 40?years after cattle grazing

Despite the detrimental impacts of invasive plants on native biodiversity, ecosystem function, and management cost, few studies have focused on the long-term persistence of invaders. Here, we use a unique, long-term dataset to examine the recovery of northern rough fescue prairie communities, 41?years after the removal of livestock from Riding Mountain National Park, Manitoba, Canada. Our 1973 data suggest that summer grazing of plains?? rough fescue (Festuca hallii (Vasey) Piper) leads to its displacement from the plant community and increased dominance by exotic invaders. After 41?years of recovery time, historic grazing intensity remained an excellent predictor of community structure and composition. Areas classified as heavily grazed in 1973 remained characterized by exotic grasses and had significantly lower richness and diversity. While some exotic invaders persisted despite 41?years of community recovery, others were ephemeral. For example, both Poa pratensis (L.) and Bromus inermis (Leyss.) persisted, increasing in abundance across all classes of grazing intensity, suggesting that their control requires active restoration of the invaded areas. In contrast, passive restoration may be possible for a subset of ephemeral exotic species such as Taraxacum officinale, which had virtually disappeared from invaded prairies by 2010. Our long-term data provide a rare perspective into the long-term dynamics of plant invasions. Based on our findings, conservation managers will need to consider the dichotomy between persistent and ephemeral invaders and their impact on the recovery of northern prairie communities as they focus their restoration efforts against the mounting impacts of exotic plant invaders.     

Impact of Alien Plant Invaders on Pollination Networks in Two Archipelagos

Mutualistic interactions between plants and animals promote integration of invasive species into native communities. In turn, the integrated invaders may alter existing patterns of mutualistic interactions. Here we simultaneously map in detail effects of invaders on parameters describing the topology of both plant-pollinator (bi-modal) and plant-plant (uni-modal) networks. We focus on the invader Opuntia spp., a cosmopolitan alien cactus. We compare two island systems: Tenerife (Canary Islands) and Menorca (Balearic Islands). Opuntia was found to modify the number of links between plants and pollinators, and was integrated into the new communities via the most generalist pollinators, but did not affect the general network pattern. The plant uni-modal networks showed disassortative linkage, i.e. species with many links tended to connect to species with few links. Thus, by linking to generalist natives, Opuntia remained peripheral to network topology, and this is probably why native network properties were not affected at least in one of the islands. We conclude that the network analytical approach is indeed a valuable tool to evaluate the effect of invaders on native communities.     

Comprehensive population viability study of a rare endemic shrub from the high mountain zone of the Canary Islands and its conservation implications

Oceanic island ecosystems harbour many endemic plant and animal species, which are often threatened because they have only a few small populations. Many factors contribute to the biological viability of such populations, such as demography and population dynamics, breeding system and pollination ecology, seed dispersal and genetic variation. In a collaborative project, all these factors were studied in the rare endemic, predominantly monoecious shrub Bencomia exstipulata Svent. (Rosaceae), which grows exclusively in the national parks of El Teide (Tenerife) and La Caldera de Taburiente (La Palma). Demography was monitored through annual censuses of individual plants in a natural and an augmented population on Tenerife. The breeding system and reproductive success were studied through bagging and pollination experiments, and insect visitation censuses. Seed dispersal by animals was assessed using cafetaria experiments. With matrix projection models and stochastic simulations, we show that the Tenerife population was demographically stable. This was largely explainable by the high survival of adult individuals. Despite frequent germination, successful seedling recruitment was very rare. Male and female flowers occurred in separate inflorescences within individuals, although some inflorescences were mixed and some shrubs were entirely male or female. Despite frequent visits by honeybees, the species is predominantly wind pollinated. Insect-proof bags reduced seed set by 12.5%, and pollen-proof bags by 44%. Large quantities of airborne pollen were detected on unbagged sticky microscope slides, this was 56% reduced by insect-proof and 96% by pollen-proof bags. Hence, some self-pollination also seems to occur. Cafetaria experiments showed that the local lizards (Gallotia galloti Oudart) readily eat the fruits and that the seeds pass through their intestines unharmed and germinable. Since other dispersal vectors are unknown, saurochory seems the most likely mode of dispersal. Our study strongly suggests that the population of B. exstipulata on Tenerife is viable, and that there are no significant threats associated with its breeding system, pollination or seed dispersal. To alleviate the natural extinction risk typical of narrow endemics, five main conservation measures are proposed.     

Orthogonius species and diversity in Thailand (Coleoptera, Caraboidea, Orthogoniini), a result from the TIGER project

The carabid genus Orthogonius MacLeay is treated, based mainly on materials collected in Thailand through the TIGER project (the Thailand Inventory Group for Entomological Research). Among 290 specimens, 20 species are identified in total, 10 of them are new species: Orthogonius taghavianaesp. n. (Nakhon Nayok: Khao Yai National Park), Orthogonius coomanioidessp. n. (Phetchabun: Thung Salaeng Luang National Park), Orthogonius similarissp. n. (Phetchabun: Thung Salaeng Luang National Park; Loei: Phu Kradueng National Park), Orthogonius setosopalpigersp. n. (Phetchabun: Thung Salaeng Luang National Park), Orthogonius gracililamellasp. n. (Loei: Phu Kradueng National Park; Chaiyaphum: Tat Tone National Park), Orthogonius pseudochaudoirisp. n. (Phetchabum: Thung Salaeng Luang National Park; Nakhon Nayok: Khao Yai National Park), Orthogonius constrictussp. n. (Phetchabum: Thung Salaeng Luang National Park), Orthogonius pinophilussp. n. (Phetchabum: Thung Salaeng Luang National Park), Orthogonius varisp. n. (Cambodia: Siem Reap; Thailand: Ubon Ratchathani: Pha Taem National Park; Phetchabun: Thung Salaeng Luang National Park) and Orthogonius variabilissp. n. (Thailand: Phetchabun: Thung Salaeng Luang National Park; Nakhon Nayok: Khao Yai National Park; Phetchabun: Nam Nao National Park; China: Yunnan). In addition, Orthogonius mouhoti Chaudoir, 1871 and Orthogonius kirirom Tian & Deuve, 2008 are recorded in Thailand for the first time. In total, 30 species of Orthogonius have been recorded from Thailand, indicating that Thailand holds one of the richest Orthogonius faunas in the world. A provisional key to all Thai species is provided. A majority of Thai Orthogonius species are endemic. Among the ten national parks in which orthogonine beetles were collected, Thung Salaeng Luang holds the richest fauna, including 16 species.     

THE GIRAFFE OF NAIROBI NATIONAL PARK: HOME RANGE, SEX RATIOS, THE HERD, AND FOOD

The giraffe of Nairobi National Park, Kenya have been studied for one year. Each animal seen has been photographed from the left side and the pattern on the neck used to recognize each individual. While the pattern may become darker with age, it does not significantly change in detail even over many years. At present 65 adult male, 72 adult female and 30 immature giraffe can be recognized. Movements of individuals are described as well as associations with other individuals. The 3ex ratio of the giraffe is discussed in relation to that found in the plains ungulates. The population of giraffe in the Park is considered to be particularly high and the relation of giraffe to the vegetation is discussed briefly.     

Diversity of rodents and shrews along an elevational gradient in Bwindi Impenetrable National Park, south-western Uganda

Small mammal species diversity in the major vegetation zones of Bwindi Impenetrable National Park is discussed in relation to altitude. Species richness of the small mammals was found to decrease with an increase in altitude. The main factors accounting for the observed diversity are the wide altitudinal variation and a complex array of vegetation types. Sixty‐seven species of rodents and shrews were found to exist in the Park; 47 of which were rodents and 20 shrews. Of these, 26 species are new to the Bwindi Park list. Three species have probably not been described before. The study found 10 species of small mammals to be Albertine Rift endemics. Three genera are recorded in Uganda for the first time: Rwenzorisorex, Suncus and Paracrocidura. Five species are new records for East Africa. These are Crocidura stenocephala, Lophuromys rahmi, L. medicaudatus, Paracrocidura maxima and Hylomyscus aeta. Because of the high endemism of plants, butterflies, birds and now of small mammal species, Bwindi forest is a unique biodiversity hotspot and is among the highest conservation priorities in the Albertine Rift.     

Short Lag Times for Invasive Tropical Plants: Evidence from Experimental Plantings in Hawai'i

Background

The lag time of an invasion is the delay between arrival of an introduced species and its successful spread in a new area. To date, most estimates of lag times for plants have been indirect or anecdotal, and these estimates suggest that plant invasions are often characterized by lag times of 50 years or more. No general estimates are available of lag times for tropical plant invasions. Historical plantings and documentation were used to directly estimate lag times for tropical plant invasions in Hawai''i.

Methodology/Principal Findings

Historical planting records for the Lyon Arboretum dating back to 1920 were examined to identify plants that have since become invasive pests in the Hawaiian Islands. Annual reports describing escape from plantings were then used to determine the lag times between initial plantings and earliest recorded spread of the successful invaders. Among 23 species that eventually became invasive pests, the average lag time between introduction and first evidence of spread was 14 years for woody plants and 5 years for herbaceous plants.

Conclusions/Significance

These direct estimates of lag times are as much as an order of magnitude shorter than previous, indirect estimates, which were mainly based on temperate plants. Tropical invaders may have much shorter lag times than temperate species. A lack of direct and deliberate observations may have also inflated many previous lag time estimates. Although there have been documented cases of long lag times due to delayed arrival of a mutualist or environmental changes over time, this study suggests that most successful invasions are likely to begin shortly after arrival of the plant in a suitable habitat, at least in tropical environments. Short lag times suggest that controlled field trials may be a practical element of risk assessment for plant introductions.     

Invasion and eradication of the American mink in the Atlantic Islands National Park (NW Spain): a retrospective analysis

Alien predators exert severe effects on island ecosystems, and their eradication from island habitats may therefore be necessary to conserve the native biota. Efforts are being made to eradicate the American mink (Neovison vison) from the Atlantic Islands of Galicia National Park (NW Spain), a protected site inhabited by vulnerable island fauna. We applied a molecular genetic approach to elucidate the source of the invaders and to evaluate the effectiveness of the trapping programme. We collected mink scats in the field and obtained tissue samples from culled mink. Populations of feral mink were known to be present in coastal areas close to the National Park archipelagos in the 1980–1990s. However, the molecular findings suggest that these populations were not the main source of the mink populations that colonized the islands during the 2000s. Recent releases from farms directly on to the islands are a more likely source of these invaders. Genetic analysis suggested that mink reproduced successfully on the islands and were relatively isolated from other mainland populations. The findings also suggest that most of the culled mink were juveniles, probably because it was more difficult to catch adults. Since mink are short-lived animals, it seems that eradication may also be achieved when a large proportion of juveniles are culled in isolated and small populations.     

Phytogeography of the Kaieteur Falls, Potaro Plateau, Guyana: floral distributions and affinities

Aim The plant diversity of one location on the Guiana Shield, Kaieteur National Park in Guyana, is used to examine the various hypothesized origins of the flora and to evaluate which may best explain the current plant distributions. Location Kaieteur National Park is located on eastern edge of the Potaro Plateau in central Guyana, South America. The species examined have distributions that vary from local to global. Methods The distribution patterns of the families, genera and species known from Kaieteur are examined using generalized distribution patterns. Results Data on distribution patterns, elevation and habitat were gathered from 131 flowering plant families, 517 genera and 1227 species. These plants represent all taxa that are currently known to occur in the area of the original Kaieteur National Park. Families tend to have cosmopolitan or pantropical distribution, genera are mostly neotropical and at the species level, most species are restricted to the Guiana Shield (c. 40%), northern South America (69%) or neotropical (96%) in distribution, each level inclusive of the previous. Conclusions The flora at the study site in Kaieteur National Park has its strongest affinity with the Guiana Shield; 42.1% of the species have a distribution that corresponds with the Shield or is more restricted within the Shield. There is a distinct flora on the Guiana Shield and its affinities lie with the flora of northern South American and beyond that, the neotropics. The flora is not closely affiliated with the floras of the Brazilian Shield, the Amazon, the Andes, the eastern coastal forests of Brazil, southern South America, or Africa as has been previous suggested.     

Maintenance management and eradication of established aquatic invaders

Although freshwater invasions have not been targeted for maintenance management or eradication as often as terrestrial invasions have, attempts to do so are frequent. Failures as well as successes abound, but several methods have been improved and new approaches are on the horizon. Many freshwater fish and plant invaders have been eliminated, especially by chemical and physical methods for fishes and herbicides for plants. Efforts to maintain invasive freshwater fishes at low levels have sometimes succeeded, although continuing the effort has proven challenging. By contrast, successful maintenance management of invasive freshwater plants is uncommon, although populations of several species have been managed by biological control. Invasive crayfish populations have rarely been controlled for long. Marine invasions have proven far less tractable than those in fresh water, with a few striking eradications of species detected before they had spread widely, and no marine invasions have been substantially managed for long at low levels. The rapid development of technologies based on genetics has engendered excitement about possibly eradicating or controlling terrestrial invaders, and such technologies may also prove useful for certain aquatic invaders. Methods of particular interest, alone or in various combinations, are gene-silencing, RNA-guided gene drives, and the use of transgenes.

     

A global comparison of plant invasions on oceanic islands

Oceanic islands have long been considered to be particularly vulnerable to biotic invasions, and much research has focused on invasive plants on oceanic islands. However, findings from individual islands have rarely been compared between islands within or between biogeographic regions. We present in this study the most comprehensive, standardized dataset to date on the global distribution of invasive plant species in natural areas of oceanic islands. We compiled lists of moderate (5–25% cover) and dominant (>25% cover) invasive plant species for 30 island groups from four oceanic regions (Atlantic, Caribbean, Pacific, and Western Indian Ocean). To assess consistency of plant behaviour across island groups, we also recorded present but not invasive species in each island group.We tested the importance of different factors discussed in the literature in predicting the number of invasive plant species per island group, including island area and isolation, habitat diversity, native species diversity, and human development. Further we investigated whether particular invasive species are consistently and predictably invasive across island archipelagos or whether island-specific factors are more important than species traits in explaining the invasion success of particular species.We found in total 383 non-native spermatophyte plants that were invasive in natural areas on at least one of the 30 studied island groups, with between 3 and 74 invaders per island group. Of these invaders about 50% (181 species) were dominants or co-dominants of a habitat in at least one island group. An extrapolation from species accumulation curves across the 30 island groups indicates that the total current flora of invasive plants on oceanic islands at latitudes between c. 35°N and 35°S may eventually consist of 500–800 spermatophyte species, with 250–350 of these being dominant invaders in at least one island group. The number of invaders per island group was well predicted by a combination of human development (measured by the gross domestic product (GDP) per capita), habitat diversity (number of habitat types), island age, and oceanic region (87% of variation explained). Island area, latitude, isolation from continents, number of present, non-native species with a known invasion history, and native species richness were not retained as significant factors in the multivariate models.Among 259 invaders present in at least five island groups, only 9 species were dominant invaders in at least 50% of island groups where they were present. Most species were invasive only in one to a few island groups although they were typically present in many more island groups. Consequently, similarity between island groups was low for invader floras but considerably higher for introduced (but not necessarily invasive) species – especially in pairs of island groups that are spatially close or similar in latitude. Hence, for invasive plants of natural areas, biotic homogenization among oceanic islands may be driven by the recurrent deliberate human introduction of the same species to different islands, while post-introduction processes during establishment and spread in natural areas tend to reduce similarity in invader composition between oceanic islands. We discuss a number of possible mechanisms, including time lags, propagule pressure, local biotic and abiotic factors, invader community assembly history, and genotypic differences that may explain the inconsistent performance of particular invasive species in different island groups.     

南滇池国家湿地公园外来园林植物生态风险评价

[目的]通过构建南滇池国家湿地公园外来园林植物生态风险评价体系,推进外来园林植物的有效判定、有利运用和有别管控,探讨国家湿地公园前期建设中存在外来植物科学防控问题,为各类生态湿地公园的建设和发展提供参考.[方法]对南滇池国家湿地公园园林植物物种组成和外来植物入侵现状进行全面普查,通过文献研究和专家咨询,构建南滇池国家湿...     

大学与国家公园的合作伙伴关系：课堂、户外实验室与世界之窗

2016年美国国家公园系统庆祝其成立100周年。在过去的100年间,作为国家公园的合作伙伴,美国的大学一直致力于为国家公园提供科学、教育和培训方面的支持。在中小学阶段,国家公园就成为学生们的学习场所。大学生在读期间会以实习生和季节工的身份参加国家公园的实践。研究生在完成论文和论文项目时为国家公园提供必要的研究,而所有参与者也就成了传递国家公园价值的更好的老师。这种支持有助于实现公园保护目标、解决公园面临的问题。同时,为在校学生和毕业后的学生提供了丰富学习经验的平台。为此还成立了专门的行政机构,以促进学校与公园的沟通、签订合约、建立合作伙伴。美国的大学与国家公园共同创造了一种有利于学术研究和管理实践的强有力合作伙伴关系,为世界以及中国国家公园体制的建设树立了很好的榜样。     

Naturalization of exotic plant species in north‐eastern North America: trends and detection capacity

Aim To reconstruct historical naturalization trends of exotic vascular plants in Quebec and Massachusetts, two regions that experienced fluctuations in their herbarium specimen collection efforts. We hypothesized that the observed trends are linked to the collection effort and that they differ according to the motive for plant introduction. Methods A checklist of naturalized exotic plant taxa for Quebec, including oldest proof of naturalization and motive for introduction, was built from herbaria, journals, dissertations, theses, bulletins, websites and unpublished records. For Massachusetts, we used the checklist of Sorrie (2005; Rhodora, 107 , 284–329). The collection effort was estimated from a pool of species with specimens from the five largest Quebec herbaria and from the Harvard University Herbarium. Results Naturalization trends of exotic plants in Quebec are similar to those observed in Massachusetts. A large part of the plants naturalized in the 17th, 18th or 19th centuries, with very little naturalization during the last 30–90 years. In general, there is a significant statistical link between herbarium specimen collection effort and the discovery of new naturalized plant taxa. Very few utilitarian plants naturalized in either region during the 20th century. In Quebec, a high number of ornamental plants naturalized during the last 100 years. Main conclusions The link between herbarium specimen collection effort and the discovery of new naturalized plants is real, although not as straightforward as it seems. Our analysis suggests that at least part of the decline in the number of new naturalized exotic plants observed in Quebec and Massachusetts during the last 30–90 years is a direct consequence of the low interest for traditional floristic studies. However, the possibility of a real decline cannot be ruled out. We nevertheless provide here one of the first pieces of evidence of the potential consequences of the decline of local plant collection for environmental management and especially for early detection systems of new invaders.     

Risk assessment for invasiveness differs for aquatic and terrestrial plant species

Predictive tools for preventing introduction of new species with high probability of becoming invasive in the U.S. must effectively distinguish non-invasive from invasive species. The Australian Weed Risk Assessment system (WRA) has been demonstrated to meet this requirement for terrestrial vascular plants. However, this system weights aquatic plants heavily toward the conclusion of invasiveness. We evaluated the accuracy of the WRA for 149 non-native aquatic species in the U.S., of which 33 are major invaders, 32 are minor invaders and 84 are non-invaders. The WRA predicted that all of the major invaders would be invasive, but also predicted that 83% of the non-invaders would be invasive. Only 1% of the non-invaders were correctly identified and 16% needed further evaluation. The resulting overall accuracy was 33%, dominated by scores for invaders. While the overall accuracy increased to 57% when the points assigned to aquatic life forms were removed, 57% of the non-invaders required further evaluation rather than were identified as having low probability of naturalizing. Discrimination between non-invaders and invaders would require an increase in the threshold score from the standard of 6 for this system to 19. That higher threshold resulted in accurate identification of 89% of the non-invaders and over 75% of the major invaders. Either further testing for definition of the optimal threshold or a separate screening system will be necessary for accurately predicting which freshwater aquatic plants are high risks for becoming invasive.     

STUDIES ON THE FOOD HABITS OF LESSER KUDU IN TSAVO NATIONAL PARK, KENYA

As part of a broader ecological investigation, in the framework of the Tsavo Research Project, food habits of lesser kudu have been studied during 2 y in Tsavo National Park (East). Free-ranging lesser kudu were observed, from a Land Rover, while feeding in different habitats and at different times of the year. Each time one animal fed on one individual plant was noted as one “food record”; some 2000 records are analysed in this paper. Leaves of trees and shrubs constitute the main bulk of the diet of lesser kudu. Creepers and vines, herbs, grasses, fruits and tubers of some root succulents contribute variable but relatively small proportions of the food. Pronounced local and seasonal variations in the composition of the diet were found. Local variations are mainly a result of differences in the vegetation of the different habitats. Seasonal variations are caused by changes in the vegetation's condition, depending on rainfall. Deciduous trees and bushes, herbs, climbers and grasses account for much smaller proportions of the diet during the dry season, when evergreen species are crucial for survival. Lesser kudu feed on a wide variety of plants, utilizing all layers of the vegetation that they can reach, at least to some extent. A total of 105 plant species have so far been recorded as being eaten by lesser kudu. With regard to food only, the vegetation changes in Tsavo National Park do not appear to have had any adverse effects on the population of lesser kudu. However, the amount of suitably structured habitat has been substantially reduced in recent years. If present trends continue, it may decrease further, to the point of jeopardizing the future of lesser kudu in large parts of Tsavo National Park.     

贵州玉舍国家森林公园种子植物区系研究

玉舍国家森林公园位于贵州西部的六盘水市水城县南部。根据多年的考察、鉴定、资料整理和统计,有种子植物122科373属923种。通过对该区种子植物属的区系分析结果:有14个分布区类型17个变型。热带分布属105属,占总属数的30.97%,温带分布属223属,占总属数的65.78%。显示了该区温带成分的特性。植物区系成分复杂,起源古老,分布有许多单型属和古老的孑遗植物,共有珍稀植物19种,其中国家一级保护植物2种,国家二级保护植物8种,国家三级保护植物3种,尚未列入保护等级的有6种。