Hubbard Brook Experimental Forest: Soil Freezing Study (SFS) In Situ Measurements of Snow and Soil Frost Depth

Climate models for the northeastern United States (U.S.) over the next
century predict an increase in air temperature between 2.8 and 4.3 °C
and a decrease in the average number of days per year when a snowpack
will cover the forest floor (Hayhoe et al. 2007, 2008; Campbell et al.
2010). Studies of forest dynamics in seasonally snow-covered
ecosystems have been primarily conducted during the growing season,
when most biological activity occurs. However, in recent years
considerable progress has been made in our understanding of how winter
climate change influences dynamics in these forests. The snowpack
insulates soil from below-freezing air temperatures, which facilitates
a significant amount of microbial activity. However, a smaller
snowpack and increased depth and duration of soil frost amplify losses
of dissolved organic C and NO3- in leachate, as well as N2O released
into the atmosphere. The increase in nutrient loss following increased
soil frost cannot be explained by changes in microbial activity alone.
More likely, it is caused by a decrease in plant nutrient uptake
following increases in soil frost. We conducted a snow-removal
experiment at Hubbard Brook Experimental Forest to determine the
effects of a smaller winter snowpack and greater depth and duration of
soil frost on trees, soil microbes, and arthropods.

A number of publications have been based on these data: Comerford et al. 2013,
Reinmann et al. 2019, Templer 2012, and Templer et al. 2012.

These data were gathered as part of the Hubbard Brook Ecosystem Study
(HBES). The HBES is a collaborative effort at the Hubbard Brook
Experimental Forest, which is operated and maintained by the USDA
Forest Service, Northern Research Station.

Campbell JL, Ollinger SV, Flerchinger GN, Wicklein H, Hayhoe K, Bailey AS. Past and projected future changes in snowpack and soil frost at the Hubbard Brook Experimental Forest, New Hampshire, USA. Hydrological Processes. 2010; 24:2465–2480.

Comerford DP, PG Schaberg, PH Templer, AM Socci, JL Campbell, and KF
Wallin. 2013. Influence of experimental snow removal on root and
canopy physiology of sugar maple trees in a northern hardwood forest.
Oecologia 171:261-269.

Hayhoe K, Wake CP, Huntington TG, Luo LF, Schwartz MD, Sheffield J, et al. Past and future changes
in climate and hydrological indicators in the US Northeast. Climate Dynamics. 2007; 28:381–407.

Hayhoe, K., Wake, C., Anderson, B. et al. Regional climate change projections for the Northeast USA.
Mitig Adapt Strateg Glob Change 13, 425–436 (2008). https://doi.org/10.1007/s11027-007-9133-2.

Reinmann AB, J Susser, EMC Demaria, PH Templer. 2019. Declines in northern forest tree growth
following snowpack decline and soil freezing.  Global Change Biology 25:420-430.

Templer PH. 2012. Changes in winter climate: soil frost, root injury,
and fungal communities (Invited). Plant and Soil 35: 15-17

Templer PH , AF Schiller, NW Fuller, AM Socci, JL Campbell, JE Drake,
and TH Kunz. 2012. Impact of a reduced winter snowpack on litter
arthropod abundance and diversity in a northern hardwood forest
ecosystem. Biology and Fertility of Soils 48:413-424.

美国东北部未来一个世纪的气候模型（Climate models）预测，气温将上升2.8至4.3°C，且每年森林地表被积雪层（snowpack）覆盖的平均天数会减少（Hayhoe等，2007,2008；Campbell等，2010）。

针对季节性积雪覆盖生态系统（seasonally snow-covered ecosystems）的森林动态（forest dynamics）研究，主要集中在生物活动最活跃的生长季（growing season）。然而，近年来，我们对冬季气候变化如何影响这些森林动态的理解取得了显著进展。

积雪层可隔热土壤免受冰点以下气温的影响，从而促进大量微生物活动（microbial activity）。然而，积雪层减少以及土壤冻深和冻期的增加，会加剧淋溶物中溶解有机碳（dissolved organic C）和硝酸根离子（NO3-）的损失，以及向大气释放的氧化亚氮（N2O）。

土壤冻害加剧后养分损失的增加，不能仅用微生物活动的变化来解释。更可能的原因是，土壤冻害加剧导致植物养分吸收（plant nutrient uptake）减少。

我们在Hubbard Brook实验林开展了积雪移除实验（snow-removal experiment），以确定冬季积雪层减少及土壤冻深、冻期增加对树木、土壤微生物和节肢动物（arthropods）的影响。

多项研究基于这些数据发表：Comerford等，2013；Reinmann等，2019；Templer，2012；Templer等，2012。

这些数据是Hubbard Brook生态系统研究（HBES）的一部分。HBES是在Hubbard Brook实验林开展的合作项目，该实验林由美国农业部林务局北部研究站运营和维护。

Campbell JL, Ollinger SV, Flerchinger GN, Wicklein H, Hayhoe K, Bailey AS. 美国新罕布什尔州Hubbard Brook实验林积雪层与土壤冻害的过去及未来预测变化. 《水文过程》. 2010; 24:2465–2480.

Comerford DP, PG Schaberg, PH Templer, AM Socci, JL Campbell, and KF Wallin. 2013. 实验性积雪移除对北方硬木林糖槭树根与冠层生理的影响. 《生态学杂志》. 2013;171:261-269.

Hayhoe K, Wake CP, Huntington TG, Luo LF, Schwartz MD, Sheffield J, et al. 美国东北部气候与水文指标的过去及未来变化. 《气候动力学》.2007;28:381–407.

Hayhoe, K., Wake, C., Anderson, B. et al. 美国东北部区域气候变化预测. 《全球变化的减缓与适应策略》.2008;13:425–436. https://doi.org/10.1007/s11027-007-9133-2.

Reinmann AB, J Susser, EMC Demaria, PH Templer. 2019. 积雪层减少与土壤冻害后北方森林树木生长的下降. 《全球变化生物学》.2019;25:420-430.

Templer PH. 2012. 冬季气候的变化：土壤冻害、根系损伤与真菌群落（特邀）. 《植物与土壤》.2012;35:15-17.

Templer PH, AF Schiller, NW Fuller, AM Socci, JL Campbell, JE Drake, and TH Kunz. 2012. 冬季积雪层减少对北方硬木林生态系统凋落物节肢动物丰度与多样性的影响. 《土壤生物学与肥力》.2012;48:413-424.