title: Effects of warming on chlorophyll degradation and carbohydrate accumulation of Alpine herbaceous species during plant senescence on the Tibetan Plateau.
abstract: 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.
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Changguang
authors.initials: C
authors.lastname: Shi
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China.
authors.forename: Geng
authors.initials: G
authors.lastname: Sun
authors.affiliation: Center for Ecological Studies, Sichuan Academy of Grassland Sciences, Chengdu, China.
authors.forename: Hongxuan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Center for Ecological Studies, Sichuan Academy of Grassland Sciences, Chengdu, China.
authors.forename: Bingxue
authors.initials: B
authors.lastname: Xiao
authors.affiliation: Center for Ecological Studies, Sichuan Academy of Grassland Sciences, Chengdu, China.
authors.forename: Bai
authors.initials: B
authors.lastname: Ze
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China.
authors.forename: Nannan
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China; Ecosystem Services, International Center for Integrated Mountain Development (ICIMOD), Kathmandu, Nepal.
authors.forename: Ning
authors.initials: N
authors.lastname: Wu
mesh_terms: D050260:Carbohydrate Metabolism; D002734:Chlorophyll / Q000378:metabolism*; D031882:Delphinium / Q000254:growth & development / Q000378:metabolism*; D031749:Elymus / Q000254:growth & development / Q000378:metabolism*; D057232:Global Warming; D057445:Plant Dormancy; D018515:Plant Leaves / Q000378:metabolism; D012621:Seasons; D018609:Tibet
chemical_list: D002734:Chlorophyll