Plant senescence is a critical life history process accompanied by chlorophyll degradation and has large implications for nutrient resorption and carbohydrate storage. Although photoperiod governs much of seasonal leaf senescence in many plant species, temperature has also been shown to modulate this process. Therefore, we hypothesized that climate warming would significantly impact the length of the plant growing season and ultimate productivity. To test this assumption, we measured the effects of simulated autumn climate warming paradigms on four native herbaceous species that represent distinct life forms of alpine meadow plants on the Tibetan Plateau. Conditions were simulated in open-top chambers (OTCs) and the effects on the degradation of chlorophyll, nitrogen (N) concentration in leaves and culms, total non-structural carbohydrate (TNC) in roots, growth and phenology were assessed during one year following treatment. The results showed that climate warming in autumn changed the senescence process only for perennials by slowing chlorophyll degradation at the beginning of senescence and accelerating it in the following phases. Warming also increased root TNC storage as a result of higher N concentrations retained in leaves; however, this effect was species dependent and did not alter the growing and flowering phenology in the following seasons. Our results indicated that autumn warming increases carbohydrate accumulation, not only by enhancing activities of photosynthetic enzymes (a mechanism proposed in previous studies), but also by affecting chlorophyll degradation and preferential allocation of resources to different plant compartments. The different responses to warming can be explained by inherently different growth and phenology patterns observed among the studied species. The results implied that warming leads to changes in the competitive balance among life forms, an effect that can subsequently shift vegetation distribution and species composition in communities.

Yak (Bos grunniens L.) herding plays an important role in the domestic economy throughout much of the Asian highlands. Yak represents a major mammal species of the rangelands found across the Asian highlands from Russia and Kyrgyzstan in the west to the Hengduan Mountains of China in the east. Yak also has great cultural significance to the people of the Asian highlands and is closely interlinked to the traditions, cultures, and rituals of the herding communities. However, increasing issues like poverty, environmental degradation, and climate change have changed the traditional practices of pastoralism, isolating and fragmenting herders and the pastures they have been using for many years. Local cultures of people rooted in the practice of yak herding are disappearing. Therefore, it is very important to document the socioeconomic and cultural aspects of yak herding. The broad aim of this paper was to provide a brief overview on the geographical distribution of yak in the Asian highlands and to provide in-depth information on yak-herding ethnic communities, the sociocultural aspect associated with yak herding, and challenges and emerging opportunities for yak herding in the Asian highlands. Altogether, 31 ethnic groups in 10 different countries of Asia and their cultures are documented herein. Yak was found to be utilized for many different household purposes, and to have cultural and religious aspects. Unfortunately, yak rearing and related traditions have been losing their charm in recent years due to modernization and several other environmental issues. Lastly, we suggest that there is an urgent need to take action to minimize the challenges faced by yak-herding mountain communities to conserve the traditional pastoral system and associated cultures of these ethnic communities.