Historian Mark B. Tauger of West Virginia University suggests that the famine was caused by a combination of factors, specifically low harvest due to natural disasters combined with increased demand for food caused by the industrialization and urbanization, and grain exports by the Soviet Union at the same time. The industrialization became a starting mechanism of the famine. Stalin's First Five-Year Plan, adopted by the party in 1928, called for rapid industrialization of the economy. With the greatest share of investment put into heavy industry, widespread shortages of consumer goods occurred while the urban labor force was also increasing. Collectivization employed at the same time was expected to improve agricultural productivity and produce grain reserves sufficiently large to feed the growing urban labor force. The anticipated surplus was to pay for industrialization. Kulaks who were the wealthier peasants encountered particular hostility from the Stalin regime. About one million kulak households (1,803,392 people according to Soviet archival data ) were liquidated by the Soviet Union. The kulaks had their property confiscated and were executed, imprisoned in Gulags, or deported to penal labor colonies in neighboring lands in a process called Dekulakization. Forced collectivization of the remaining peasants was often fiercely resisted resulting in a disastrous disruption of agricultural productivity. Forced collectivization helped achieve Stalin's goal of rapid industrialization but it also contributed to a catastrophic famine in 1932–33.